Sensor device

Abstract

This sensor device comprises: a target (25) having a base part (250) that rotates about a rotation axis (Or) due to rotation of an object to be detected and that is displaced due to displacement of the object to be detected, a plurality of protrusions (252) that protrude from the base part (250) and that are arranged at intervals in the circumferential direction (Dc), and a recess (254) formed between mutually adjacent protrusions (252); a first coil (31) that outputs a voltage having periodicity corresponding to changes in a magnetic field changing due to the protrusions (252); a second coil (32) that is aligned in the circumferential direction (Dc) with the first coil (31) and outputs a voltage having a periodicity corresponding to the change in the magnetic field changing due to the protrusions (252), said voltage having a different phase from the voltage of the first coil (31); and a detection unit (50) that detects the rotation angle and displacement of the object to be detected on the basis of the voltages of the first coil (31) and the second coil (32).

Description

Sensor Device CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Patent Application No. 2023-185598 filed on October 30, 2023, Japanese Patent Application No. 2024-039098 filed on March 13, 2024, and Japanese Patent Application No. 2024-173360 filed on October 2, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a sensor device.

[0003] As described in Patent Document 1, a sensor has been known that detects the rotation angle of a motor rotor using a conductor pattern and a sensor body. The conductor pattern of this sensor has a shape whose width changes trigonometrically with the rotation angle of the rotor. The sensor body also has multiple pattern coils. A voltage is applied to each of the pattern coils to generate eddy currents in the conductor pattern. The rotation angle of the rotor is detected by the change in voltage generated in the pattern coils by the eddy currents.

[0004] JP 2009-77500 A

[0005] Incidentally, in addition to the rotation angle of a detection object such as a motor rotor, there is a demand for detecting displacement of the detection object in the axial direction or in a direction perpendicular to the axial direction. However, the sensor described in Patent Document 1 can detect the rotation angle of the detection object, but cannot detect displacement of the detection object in the axial direction or in a direction perpendicular to the axial direction. An object of the present disclosure is to provide a sensor device that detects the rotation angle of the detection object and also detects displacement of the detection object.

[0006] According to one aspect of the present disclosure, a sensor device includes a conductor having a base portion that rotates around a rotation axis due to the rotation of an object to be detected and displaces due to the displacement of the object to be detected, a plurality of convex portions that protrude from the base portion and are arranged at intervals in a circumferential direction, which is a direction around the rotation axis, and concave portions formed between adjacent convex portions, a first coil that outputs a voltage having a periodicity corresponding to changes in a magnetic field that are caused by the convex portions, a second coil that is arranged circumferentially with the first coil and outputs a voltage having a periodicity corresponding to changes in the magnetic field that are caused by the convex portions, the voltage being out of phase with the voltage of the first coil, and a detection portion that detects the rotation angle and displacement of the object to be detected based on the voltages of the first coil and the second coil.

[0007] As a result, the rotation angle of the detection object is detected, and the displacement of the detection object is also detected.

[0008] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below.

[0009] 1 is a cross-sectional view of an in-wheel motor using the sensor device of a first embodiment. FIG. 3 is a diagram showing a target of the sensor device. FIG. 4 is a diagram showing the target, receiving coil, excitation coil, and substrate of the sensor device. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. FIG. 5 is a diagram showing the receiving coil, excitation coil, AC voltage generating circuit, and detection unit of the sensor device. FIG. 6 is a diagram showing the detection unit of the sensor device. FIG. 7 is a relationship diagram between the rotation angle and the voltage of the receiving coil. FIG. 8 is a relationship diagram between the rotation angle and the voltage of the receiving coil after envelope processing. FIG. 9 is a relationship diagram between the rotation angle and the voltage difference of the receiving coil after envelope processing. FIG. 10 is a relationship diagram between the amount of displacement in the axial direction and the voltage difference of the receiving coil after envelope processing. FIG. 11 is a relationship diagram between the amount of displacement in the radial direction and the sum of the voltage of the receiving coil after envelope processing. FIG. 12 is a diagram showing the target, receiving coil, excitation coil, and substrate of the sensor device of a second embodiment. FIG. 13 is a diagram showing the receiving coil, excitation coil, AC voltage generating circuit, and detection unit of the sensor device. FIG. 14 is a diagram showing the target of the sensor device of a third embodiment. FIG. 15 is a diagram for explaining a map of the sensor device of a fourth embodiment. 10. A diagram showing the relationship between the rotation angle, the voltage difference of the receiver coil, and the displacement in the axial direction to explain the processing of the detection unit of the sensor device of the fifth embodiment. A diagram showing the receiver coil, AC voltage generating circuit, and detection unit of the sensor device of the sixth embodiment. A diagram showing the detection unit of the sensor device of the seventh embodiment. A diagram showing the target, receiver coil, excitation coil, and substrate of the sensor device of the eighth embodiment. A diagram showing the target, receiver coil, excitation coil, and substrate of the sensor device of the ninth embodiment. A diagram showing the target, receiver coil, excitation coil, and substrate of the sensor device of the tenth embodiment. A diagram showing the target, receiver coil, excitation coil, and substrate of the sensor device of the eleventh embodiment. A diagram showing the target, receiver coil, excitation coil, and substrate of the sensor device of the twelfth embodiment. A diagram showing the target, receiver coil, excitation coil, and substrate of the sensor device of the thirteenth embodiment. A diagram showing the target, receiver coil, excitation coil, and substrate of the sensor device of the fourteenth embodiment. A diagram showing the target, receiver coil, excitation coil, and substrate of the sensor device of the fifteenth embodiment. A diagram showing the target, receiver coil, excitation coil, and substrate of the sensor device of the sixteenth embodiment. 28 is a diagram showing the target, the receiving coil, the exciting coil, and the substrate of the sensor device according to the seventeenth embodiment. FIG. 29 is a cross-sectional view taken along the line XXIX-XXIX in FIG. 28. FIG. 29 is a schematic cross-sectional view showing the state when the target is displaced in the radial direction.12. A diagram showing the relationship between the amount of displacement in the radial direction and the amount of change in voltage. A diagram showing a target, a receiving coil, an excitation coil, and a substrate of a sensor device of an 18th embodiment. A diagram showing a target, a receiving coil, an excitation coil, and a substrate of a sensor device of a 20th embodiment. A diagram showing a target, a receiving coil, an excitation coil, and a substrate of a sensor device of a 21st embodiment. A diagram showing a target, a receiving coil, an excitation coil, and a substrate of a sensor device of a 22nd embodiment. A diagram showing a target, a receiving coil, an excitation coil, and a substrate of a sensor device of a 23rd embodiment. A diagram showing a target, a receiving coil, an excitation coil, and a substrate of a sensor device of a 24th embodiment. A diagram showing a detection unit of a sensor device of a 25th embodiment. A diagram showing the relationship between a first voltage difference and a second voltage difference. A diagram showing the relationship between corrected first voltage differences and second voltage differences. A diagram showing a target, a receiving coil, an excitation coil, and a substrate of a sensor device. A diagram showing the relationship between the displacement direction, the voltage of each coil, the first voltage difference, the second voltage difference, and the corrected first voltage differences and second voltage differences. 50. A diagram showing the relationship between the corrected first voltage difference and the second voltage difference when the target is displaced in the radial direction. A diagram showing the relationship between the corrected first voltage difference and the second voltage difference when the target is displaced in the radial direction. A diagram showing the relationship between the corrected first voltage difference and the second voltage difference when the target is displaced in the axial direction. A diagram for explaining calculation of radial and axial displacement by the detection unit. A diagram for explaining correction of lateral force by the detection unit. A diagram for explaining correction of normal load by the detection unit. A diagram for explaining calculation of radial and axial displacement by the detection unit of the sensor device of the 26th embodiment. A diagram showing the target, receiving coil, excitation coil, and substrate of the sensor device of the 27th embodiment. An enlarged view of the LI section of FIG. 50. A diagram showing the target, receiving coil, excitation coil, and substrate of the sensor device of the 28th embodiment. A diagram showing the target, receiving coil, excitation coil, and substrate of the sensor device of the 29th embodiment. A diagram showing the target, receiving coil, excitation coil, and substrate of the sensor device of the 30th embodiment. An enlarged view of the LV section of FIG. 54. 31. A diagram showing a target, a receiving coil, an exciting coil, and a substrate of a sensor device according to a 31st embodiment. 32. A diagram for explaining a map of a sensor device according to a 32nd embodiment. 33. A diagram showing a target, a receiving coil, an exciting coil, and a substrate of a sensor device according to a 33rd embodiment.61 . A diagram showing a target, a receiver coil, an excitation coil, and a substrate of a sensor device according to a thirty-fourth embodiment. 62. A diagram showing a target of a sensor device according to a thirty-fifth embodiment. 63. A diagram showing a target, a receiver coil, an excitation coil, and a substrate of a sensor device according to a thirty-sixth embodiment. 64. A diagram showing a first receiver coil of a sensor device. 65. A diagram showing a second receiver coil of a sensor device. 66. Enlarged view of section LXIV of FIG. 61 . 67. A diagram showing a target, a receiver coil, an excitation coil, and a substrate of a sensor device according to a thirty-seventh embodiment. 68. A diagram showing a target, a receiver coil, an excitation coil, and a substrate of a sensor device according to a thirty-eighth embodiment. 69. Enlarged view of section LXVII of FIG. 66 . 69. A diagram showing the relationship between displacement of a target in the radial direction and the voltages of the third receiver coil and the fourth receiver coil. 70. A diagram showing the relationship between displacement of a target in the axial direction and the voltages of the third receiver coil and the fourth receiver coil. 71. A diagram showing a target and receiver coil of a sensor device according to a thirty-ninth embodiment. 72. A diagram showing a target and receiver coil of a sensor device according to a fortieth embodiment. 73. A diagram showing a target and receiver coil of a sensor device according to a fortieth embodiment. 74. A diagram showing a target and receiver coil of a sensor device according to a fortieth embodiment. 75. A diagram showing a target and receiver coil of a sensor device according to a fortieth embodiment. 85. A diagram showing a target and a receiver coil of a sensor device of a 43rd embodiment. A diagram showing a target of a sensor device of a 44th embodiment. A diagram showing a target and a receiver coil of a sensor device. A diagram showing a target and a receiver coil of a sensor device of a 45th embodiment. A diagram showing a target and a receiver coil of a sensor device of a 46th embodiment. A diagram showing the relationship between time and the voltage of a third receiver coil and a fourth receiver coil. A diagram showing the relationship between time and the voltage of a third receiver coil and a fourth receiver coil. A diagram showing the relationship between time and the voltage of a third receiver coil and a fourth receiver coil. A diagram showing a target and a receiver coil of a sensor device of a 47th embodiment. A cross-sectional view of a target and a receiver coil of a sensor device of a 48th embodiment. A diagram showing a receiver coil and a detection unit of a sensor device. A diagram showing a target and a receiver coil of a sensor device of a 49th embodiment. A diagram showing a target, a receiver coil, an excitation coil, and a substrate of a sensor device of a 50th embodiment. An enlarged view of portion LXXXVI of FIG. 85. A diagram showing a target and a receiver coil of a sensor device of a 51st embodiment. A diagram showing a target and a receiver coil of a sensor device of a 52nd embodiment. A diagram showing a target, a receiver coil, an excitation coil, and a substrate of a sensor device of a 53rd embodiment. FIG. 4 is a diagram showing the relationship between the circumferential position and the strength of the magnetic field generated by the excitation coil.1 is a diagram showing the relationship between the rotation angle and the deviation amount from the true value of the rotation angle; 2 is a diagram showing the relationship between the circumferential position, the strength of the magnetic field generated by the excitation coil, and the position of the receiver coil; 3 is a diagram showing the relationship between the rotation angle and the deviation amount from the true value of the rotation angle; 4 is a diagram showing the target, receiver coil, excitation coil, and substrate of the sensor device of the 54th embodiment; 5 is a diagram showing the target and first receiver coil of the sensor devices of the 55th and 56th embodiments; 6 is a diagram showing the relationship between the distance from the outer end of the coil to the outer end of the convex portion in the radial direction and the voltage of the receiver coil when the target moves in the axial direction; 7 is a diagram showing the relationship between the distance from the outer end of the coil to the outer end of the convex portion in the radial direction and the voltage of the receiver coil when the target moves in the axial direction, and the voltage of the receiver coil when the target moves in the radial direction; 8 is a diagram showing the target and first receiver coil of the sensor device of the 57th embodiment; 9 is a diagram showing the relationship between the distance from the outer end of the coil to the outer end of the convex portion in the radial direction and the voltage of the receiver coil when the target moves in the radial direction; 10 is a diagram showing the target and first receiver coil of the sensor device of the 58th and 59th embodiments; 1 is a diagram showing a target and a first receiver coil of the sensor device of the 60th embodiment; 2 is a diagram showing a target and a first receiver coil of the sensor devices of the 61st and 62nd embodiments; 3 is a diagram showing a target and a first receiver coil of the sensor device of the 63rd embodiment; 4 is a diagram showing a target and a first receiver coil of the sensor devices of the 64th and 65th embodiments; 5 is a diagram showing a target and a first receiver coil of the sensor device of the 66th embodiment; 6 is a diagram showing a target and a first receiver coil of the sensor device of the 67th embodiment; 7 is a diagram showing a target and a second receiver coil of the sensor device; 8 is a diagram showing a target and a third receiver coil of the sensor device; 9 is a diagram showing a target and a fourth receiver coil of the sensor device; 10 is a diagram showing the relationship between the rotation angle and the voltage of the receiver coil in the sensor device of the 67th embodiment and a comparative example; 11 is a diagram showing a target and a first receiver coil of the sensor device of the 68th embodiment; 12 is a diagram showing a target and a first receiver coil of the sensor device of the 69th embodiment; 13 is a diagram showing a target and a first receiver coil of the sensor device of the 70th embodiment; 14 is a diagram showing a target and a first receiver coil of the sensor device of the 71st embodiment; 15 is a cross-sectional view of the target and the first receiver coil of the sensor device of the 72nd embodiment. FIG. 4 is a cross-sectional view of a target and a second receiving coil of the sensor device.77. A cross-sectional view of a target and a third receiver coil of a sensor device. A cross-sectional view of a target and a fourth receiver coil of a sensor device. A diagram showing a first receiver coil of a sensor device of a 73rd embodiment. An enlarged cross-sectional view of the first receiver coil. A diagram showing a second receiver coil of a sensor device. A diagram showing a third receiver coil of a sensor device. A diagram showing a fourth receiver coil of a sensor device. A perspective view of a target of a sensor device of a 74th embodiment. A perspective view of a target of a sensor device of a 75th embodiment. A cross-sectional view of a target of a sensor device of a 76th embodiment. A diagram showing a target, a receiver coil, an excitation coil, and a substrate of a sensor device of a 77th embodiment. A diagram showing a target, a receiver coil, an excitation coil, and a substrate of a sensor device of a 78th embodiment. A diagram showing a target, a receiver coil, an excitation coil, and a substrate of a sensor device of a 79th embodiment. A diagram showing a target, a receiver coil, an excitation coil, and a substrate of a sensor device of an 80th embodiment. A diagram showing a target, a receiver coil, an excitation coil, and a substrate of a sensor device of an 81st embodiment. A diagram showing the relationship between a rotation angle, a rotation angle component of a voltage, and a radial displacement component. FIG. 1 is a diagram showing a target, a receiving coil, an excitation coil, and a substrate of a sensor device according to an 82nd embodiment; FIG. 2 is a diagram showing a receiving coil and a detection unit of a sensor device according to an 83rd embodiment; FIG. 3 is a diagram showing a receiving coil and a detection unit of a sensor device according to an 84th embodiment; FIG. 4 is a diagram showing a target, a receiving coil, an excitation coil, and a substrate of a sensor device according to an 85th embodiment; FIG. 5 is a diagram showing a target, a receiving coil, an excitation coil, and a substrate of a sensor device according to an 86th embodiment; FIG. 6 is a diagram showing a target, a receiving coil, an excitation coil, and a substrate of a sensor device according to an 87th embodiment; FIG. 7 is a diagram showing a target, a receiving coil, an excitation coil, and a substrate of a sensor device according to an 88th embodiment; FIG. 8 is a diagram showing a target, a receiving coil, an excitation coil, and a substrate of a sensor device according to an 89th embodiment; FIG. 90 is a diagram showing a target, a receiving coil, an excitation coil, and a substrate of a sensor device according to a 91st embodiment; FIG. 92 is a diagram showing a target, a receiving coil, an excitation coil, and a substrate of a sensor device according to a 93rd embodiment; and FIG. 94 is a diagram showing a receiving coil of a sensor device according to a 94th embodiment. A diagram showing the receiving coil and detection unit of the sensor device of the 95th embodiment.101. A diagram showing a receiver coil and a detector of a sensor device of a 96th embodiment. 102. A diagram showing a receiver coil and a detector of a sensor device of a 97th embodiment. 103. A diagram showing a receiver coil, a detector, a first switch, and a second switch of a sensor device of a 98th embodiment. 104. A diagram showing a receiver coil, a detector, and a switch of a sensor device of a 99th embodiment. 105. A diagram showing a target, a receiver coil, an excitation coil, and a substrate of a sensor device of a 100th embodiment. 106. A diagram showing a target, a receiver coil, an excitation coil, and a substrate of a sensor device of a 101st embodiment. 107. A diagram showing a target, a receiver coil, an excitation coil, and a substrate of a sensor device of a 102nd embodiment. 108. A diagram showing a target of a sensor device of another embodiment. 109. A diagram showing a receiver coil and a detector of a sensor device of another embodiment.

[0010] Hereinafter, embodiments will be described with reference to the drawings. In the following embodiments, identical or equivalent parts will be denoted by the same reference numerals, and description thereof will be omitted.

[0011] First Embodiment A sensor device according to the present embodiment is used in, for example, a vehicle equipped with an in-wheel motor. First, this vehicle will be described.

[0012] As shown in FIG. 1 , the vehicle includes a wheel 10 , a tire 12 , an in-wheel motor 14 and a sensor device 20 .

[0013] The wheel 10 has a rim portion 100 and a disc portion 102. The rim portion 100 is formed in a cylindrical shape with its center on an axis extending in the vehicle width direction. The tire 12 is attached to the outer periphery of the rim portion 100. The disc portion 102 is formed in a circular plate shape with its center on an axis extending in the vehicle width direction. The disc portion 102 is connected to the outer end of the rim portion 100 in the vehicle width direction. The vehicle width direction is the width direction of the vehicle, and corresponds to the left-right direction of the vehicle.

[0014] The in-wheel motor 14 is housed in the internal space of the wheel 10 formed by the rim portion 100 and the disc portion 102. The in-wheel motor 14 rotates about an axis extending in the vehicle width direction, thereby applying rotational power to the wheel 10. In this way, the in-wheel motor 14 applies rotational power to the tire 12 attached to the wheel 10. For example, the in-wheel motor 14 is an outer rotor type motor and has a rotor 140 and a stator 160.

[0015] The rotor 140 has a magnet holding portion 142, a magnet unit 144, and a flat plate portion 146. The magnet holding portion 142 is formed in a cylindrical shape with its center on an axis extending in the vehicle width direction. Furthermore, the outer peripheral surface of the magnet holding portion 142 faces the inner peripheral surface of the rim portion 100 in the vehicle height direction. The vehicle height direction is the height direction of the vehicle, which corresponds to the up-and-down direction of the vehicle.

[0016] The magnet unit 144 is formed in a cylindrical shape centered on the axis of the magnet holder 142. The magnet unit 144 also includes a magnet. The magnet is, for example, a neodymium magnet, and is fixed to the inner circumferential surface of the magnet holder 142. Therefore, the in-wheel motor 14 is herein defined as a surface permanent magnet synchronous motor, i.e., an SPMSM. Furthermore, the magnet is magnetized so that the magnetic poles are alternately reversed in the circumferential direction of the magnet holder 142. Note that, although the in-wheel motor 14 is defined as an SPMSM here, this is not limiting. The in-wheel motor 14 may also be an interior permanent magnet synchronous motor, i.e., an IPMSM. SPMSM is an abbreviation for Surface Permanent Magnet Synchronous Motor. IPMSM is an abbreviation for Interior Permanent Magnet Synchronous Motor.

[0017] The flat plate portion 146 is formed on a disk centered on the axis of the magnet holding portion 142. The flat plate portion 146 is connected to the end of the magnet holding portion 142 on the outer side in the vehicle width direction. Holes are formed in the flat plate portion 146, and holes corresponding to the holes in the flat plate portion 146 are formed in the disk portion 102. Bolts or the like are inserted into the holes in the flat plate portion 146 and the disk portion 102. This fixes the flat plate portion 146 and the disk portion 102 together. Therefore, the rotor 140 and the wheel 10 rotate together.

[0018] The stator 160 has a stator base portion 162, bearings 164, and a stator winding 166. The stator base portion 162 includes a cylindrical portion 170, a first extension portion 171, a second extension portion 172, and a third extension portion 173.

[0019] The cylindrical portion 170 is formed in a cylindrical shape centered on the axis of the magnet holding portion 142. Furthermore, the cylindrical portion 170 is fixed to the vehicle body via, for example, a knuckle of the vehicle. The first extension portion 171 is connected to an end of the cylindrical portion 170 that is on the outer side in the vehicle width direction. The first extension portion 171 extends radially inward from the boundary with the cylindrical portion 170. The second extension portion 172 is connected to the end of the first extension portion 171 opposite the cylindrical portion 170. The second extension portion 172 extends radially inward from the boundary with the first extension portion 171. The third extension portion 173 is connected to the end of the second extension portion 172 opposite the first extension portion 171. The third extension portion 173 extends radially inward from the boundary with the second extension portion 172.

[0020] The bearing 164 is a rolling bearing, such as a radial ball bearing, and further includes an outer ring 180, an inner ring 182, and rolling elements 184.

[0021] Holes are formed in the outer ring 180, and holes corresponding to the holes in the outer ring 180 are formed in the third extension portion 173. Bolts or the like are inserted into the holes in the outer ring 180 and the third extension portion 173. In this way, the outer ring 180 and the stator base portion 162 are fixed together.

[0022] The inner ring 182 includes a cylindrical portion 186 and a flange portion 188. The cylindrical portion 186 is formed in a cylindrical shape centered on the axis of the magnet holder 142. Furthermore, the cylindrical portion 186 is formed radially inward of the cylindrical portion 170 relative to the outer ring 180 and faces the outer ring 180 in the vehicle height direction. The flange portion 188 is connected to the end of the cylindrical portion 186 that is on the outer side in the vehicle width direction. Furthermore, the flange portion 188 extends radially outward from the boundary with the cylindrical portion 186. Furthermore, the flange portion 188 has holes formed therein that correspond to the holes in the flat plate portion 146 and the disk portion 102. Furthermore, bolts inserted into the holes in the flat plate portion 146 and the disk portion 102 are inserted into the holes in the flange portion 188. This fixes the flange portion 188, the flat plate portion 146, and the disk portion 102 together.

[0023] The rolling elements 184 are balls or the like, and are disposed between the outer ring 180 and the inner ring 182. Therefore, the rotor 140 is rotatably supported relative to the stator 160 by the stator base portion 162 and the bearings 164.

[0024] The stator winding 166 is disposed on the outer peripheral surface of the cylindrical portion 170 and is disposed so as to face the magnet unit 144 in the vehicle height direction. The stator winding 166 is further connected to an inverter (not shown). The inverter is connected to a storage battery (not shown), such as a lithium-ion storage battery, and a control device (not shown). The inverter converts direct current from the storage battery into alternating current in response to a signal from the control device. The alternating current converted by the inverter flows through the stator winding 166. This generates a magnetic force in the stator winding 166. This magnetic force generated in the stator winding 166 generates rotational power in the rotor 140 having the magnet unit 144. Therefore, rotational power is imparted to the tire 12 attached to the wheel 10 connected to the rotor 140.

[0025] As will be described later, the sensor device 20 detects the rotation angle of the tire 12 as a detection target. Furthermore, the sensor device 20 detects the displacement of the tire 12 in the vehicle width direction. As a result, the sensor device 20 detects the lateral force Fy of the tire 12. Furthermore, the sensor device 20 detects the displacement of the tire 12 in the vehicle height direction. As a result, the sensor device 20 detects the vertical load Fz of the tire 12. Furthermore, the sensor device 20 outputs signals corresponding to the detected rotation angle, lateral force Fy, and vertical load Fz to the inverter control device. The control device controls the inverter based on these signals. The control device thereby controls the rotation of the tire 12, thereby controlling the running of the vehicle. The lateral force Fy is a force acting in the vehicle width direction between the ground G and the tire 12. The vertical load Fz is a force acting in the vehicle height direction between the ground G and the tire 12. Furthermore, the direction of the vertical load Fz is perpendicular to the direction of the lateral force Fy.

[0026] The vehicle is configured as described above. Next, the sensor device 20 will be described in detail.

[0027] As shown in Figures 1 to 6, the sensor device 20 includes a target 25, a substrate 30, a first receiving coil 31, a second receiving coil 32, a third receiving coil 33, a fourth receiving coil 34, an excitation coil 40, an AC voltage generating circuit 45, and a detection unit 50.

[0028] The target 25 corresponds to a conductor and is made of metal etc., and is therefore conductive. The target 25 also has a base portion 250, a protrusion 252 and a recess 254.

[0029] As shown in FIGS. 1 and 2 , the base portion 250 is formed in an annular shape centered on an axis extending in the vehicle width direction. The base portion 250 also has holes formed therein that correspond to the holes in the disk portion 102, the flat plate portion 146, and the flange portion 188. Furthermore, bolts or the like inserted into the holes in the disk portion 102, the flat plate portion 146, and the flange portion 188 are inserted into the holes in the base portion 250. This secures the base portion 250 to the disk portion 102, the flat plate portion 146, and the flange portion 188. Therefore, the base portion 250 rotates about the rotation axis Or due to the rotation of the tire 12 attached to the wheel 10. Furthermore, the base portion 250 is displaced due to the displacement of the tire 12. In this example, the rotation axis Or extends in the vehicle width direction and coincides with the axis of the magnet holder 142.

[0030] Here, the direction in which the rotation axis Or of the base portion 250 extends is referred to as the axial direction Da. The radial direction of the base portion 250 is simply referred to as the radial direction Dr. The radial direction Dr corresponds to a direction perpendicular to the rotation axis Or. The direction around the rotation axis Or is referred to as the circumferential direction Dc.

[0031] The protrusions 252 protrude from the outer end of the base portion 250 in the radial direction Dr toward the axial direction Da. As shown in FIG. 2 , the protrusions 252 are arranged at intervals in the circumferential direction Dc. Here, the number of protrusions 252 is an even number. Each protrusion 252 is formed in an arc shape centered on the rotation axis Or. The size of each protrusion 252 is the same. The protrusions 252 are spaced apart at equal intervals. Note that the terms "same" and "equal" are intended to include the manufacturing error range.

[0032] The recessed portions 254 are formed between adjacent protruding portions 252, and are arranged at intervals in the circumferential direction Dc. Furthermore, since the protruding portions 252 are all the same size and are equally spaced apart, the recessed portions 254 are all the same size and are equally spaced apart.

[0033] The substrate 30 is a printed circuit board and is formed in an arc shape centered on the rotation axis Or, as shown in FIG. 3 . The substrate 30 also has a substrate front surface 300 and a substrate back surface 302. The substrate front surface 300 is a surface perpendicular to the thickness direction of the substrate 30 and faces the convex portion 252 and the concave portion 254 in the axial direction Da. The substrate back surface 302 is a surface opposite to the substrate front surface 300 and perpendicular to the thickness direction of the substrate 30. Furthermore, the substrate back surface 302 is connected to the first extension portion 171, as shown in FIG. 1 .

[0034] 3 , the first receiving coil 31 corresponds to the first coil and is formed on the substrate surface 300. As a result, the first receiving coil 31 faces the convex portion 252 and the concave portion 254 in the axial direction Da. Therefore, the first receiving coil 31 outputs a voltage having a periodicity according to the change in the magnetic field caused by the convex portion 252, as will be described later.

[0035] The first receiving coil 31 is formed in a spiral shape extending on a plane perpendicular to the rotation axis Or. The first receiving coil 31 further includes a plurality of first linear portions 311. The first linear portions 311 are arranged at intervals in the radial direction Dr and the circumferential direction Dc. The first linear portions 311 arranged at intervals in the radial direction Dr are formed in an arc shape centered on the rotation axis Or. The first linear portions 311 are also arranged at intervals in the axial direction Da, as shown in FIG. 4 . The first linear portions 311 arranged at intervals in the axial direction Da are connected to each other by vias or the like (not shown) formed in the substrate 30.

[0036] 3 , the second receiving coil 32 corresponds to the second coil and is formed on the substrate surface 300. As a result, the second receiving coil 32 faces the convex portions 252 and the concave portions 254 in the axial direction Da. The second receiving coil 32 is also aligned with the first receiving coil 31 in the circumferential direction Dc. Therefore, as will be described later, the second receiving coil 32 outputs a voltage that has a periodicity corresponding to the change in the magnetic field caused by the convex portions 252 and that is out of phase with the voltage of the first receiving coil 31.

[0037] The second receiving coil 32 is formed in a spiral shape extending on a plane perpendicular to the rotation axis Or. The second receiving coil 32 further has a plurality of second linear portions 322. The second linear portions 322 are arranged at intervals in the radial direction Dr and the circumferential direction Dc. The second linear portions 322 arranged at intervals in the radial direction Dr are formed in an arc shape centered on the rotation axis Or. The second linear portions 322 are also arranged at intervals in the axial direction Da, similar to the first linear portions 311. The second linear portions 322 arranged at intervals in the axial direction Da are connected to each other by vias or the like (not shown) formed in the substrate 30.

[0038] The third receiving coil 33 corresponds to the third coil and is formed on the substrate surface 300. As a result, the third receiving coil 33 faces the convex portion 252 and the concave portion 254 in the axial direction Da. The third receiving coil 33 is also aligned with the first receiving coil 31 and the second receiving coil 32 in the circumferential direction Dc. Therefore, as will be described later, the third receiving coil 33 outputs a voltage that has a periodicity corresponding to the change in the magnetic field caused by the convex portion 252 and that is out of phase with the voltages of the first receiving coil 31 and the second receiving coil 32.

[0039] The third receiving coil 33 is formed in a spiral shape extending on a plane perpendicular to the rotation axis Or. The third receiving coil 33 further includes a plurality of third linear portions 333. The third linear portions 333 are arranged at intervals in the radial direction Dr and the circumferential direction Dc. The third linear portions 333 arranged at intervals in the radial direction Dr are formed in an arc shape centered on the rotation axis Or. The third linear portions 333 are also arranged at intervals in the axial direction Da, similar to the first linear portion 311 and the second linear portion 322. The third linear portions 333 arranged at intervals in the axial direction Da are connected to each other by vias (not shown) or the like formed in the substrate 30.

[0040] The fourth receiving coil 34 corresponds to the fourth coil and is formed on the substrate surface 300. As a result, the fourth receiving coil 34 faces the convex portion 252 and the concave portion 254 in the axial direction Da. The fourth receiving coil 34 is also aligned with the first receiving coil 31, the second receiving coil 32, and the third receiving coil 33 in the circumferential direction Dc. As a result, the fourth receiving coil 34 outputs a voltage that has a periodicity corresponding to changes in the magnetic field caused by the convex portion 252, as will be described later, and that is out of phase with the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34.

[0041] The fourth receiving coil 34 is formed in a spiral shape extending on a plane perpendicular to the rotation axis Or. The fourth receiving coil 34 further includes a plurality of fourth linear portions 344. The fourth linear portions 344 are arranged at intervals in the radial direction Dr and the circumferential direction Dc. The fourth linear portions 344 arranged at intervals in the radial direction Dr are formed in an arc shape centered on the rotation axis Or. The fourth linear portions 344 are also arranged at intervals in the axial direction Da, similar to the first linear portion 311, the second linear portion 322, and the third linear portion 333. The fourth linear portions 344 arranged at intervals in the axial direction Da are connected to each other by vias (not shown) or the like formed in the substrate 30.

[0042] The winding directions of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 are arbitrary. Here, the winding directions of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 are adjusted so that the direction of the current flowing due to the voltage generated in association with the rotation of the target 25, which will be described later, is the same.

[0043] Here, the angle formed by a line connecting corresponding portions of adjacent convex portions 252 with the rotation axis Or when viewed from the axial direction Da is defined as the fluctuation period α. When viewed from the axial direction Da, a line connecting the end of the first receiving coil 31 opposite the second receiving coil 32 with the rotation axis Or is defined as a first line L1. When viewed from the axial direction Da, a line connecting the end of the second receiving coil 32 opposite the first receiving coil 31 with the rotation axis Or is defined as a second line L2. When viewed from the axial direction Da, a line connecting the end of the first receiving coil 31 on the second receiving coil 32 side with the rotation axis Or is defined as a third line L3. Here, the third line L3 coincides with the line connecting the end of the second receiving coil 32 on the first receiving coil 31 side with the rotation axis Or when viewed from the axial direction Da. The angle formed by the first line L1 and the second line L2 is defined as a first angle θce1. The angle formed by the first line L1 and the third line L3 is defined as the first coil angle θc1. The angle formed by the second line L2 and the third line L3 is defined as the second coil angle θc2. When viewed from the axial direction Da, a line connecting the end of the third receiving coil 33 opposite the fourth receiving coil 34 and the rotation axis Or is defined as the fourth line L4. When viewed from the axial direction Da, a line connecting the end of the fourth receiving coil 34 opposite the third receiving coil 33 and the rotation axis Or is defined as the fifth line L5. When viewed from the axial direction Da, a line connecting the end of the third receiving coil 33 on the fourth receiving coil 34 side and the rotation axis Or is defined as the sixth line L6. Here, the sixth line L6 coincides with the line connecting the end of the fourth receiving coil 34 on the third receiving coil 33 side and the rotation axis Or when viewed from the axial direction Da. The angle formed by the fourth line L4 and the fifth line L5 is the second angle θce2. The angle formed by the fourth line L4 and the sixth line L6 is the third coil angle θc3. The angle formed by the fifth line L5 and the sixth line L6 is the fourth coil angle θc4.

[0044] The first receiving coil 31 and the second receiving coil 32 are formed so that the following relational expression (1-1) holds. Furthermore, the third receiving coil 33 and the fourth receiving coil 34 are formed so that the following relational expression (1-2) holds. For example, the first coil angle θc1 is set to α×½. The second coil angle θc2 is set to α×½. The third coil angle θc3 is set to α×½. The fourth coil angle θc4 is set to α×½.

[0045] 1 / 2×α≦θc1<θce1, 1 / 2×α≦θc1<α 1 / 2×α≦θc2<θce1, 1 / 2×α≦θc2<α ...(1-1) 1 / 2×α≦θc3<θce2, 1 / 2×α≦θc3<α 1 / 2×α≦θc4<θce2, 1 / 2×α≦θc4<α ... (1-2)

[0046] Also, here, the center of the first receiving coil 31 when viewed from the axial direction Da is referred to as the first coil center Mc1. The center of the second receiving coil 32 when viewed from the axial direction Da is referred to as the second coil center Mc2. The center of the third receiving coil 33 when viewed from the axial direction Da is referred to as the third coil center Mc3. The center of the fourth receiving coil 34 when viewed from the axial direction Da is referred to as the fourth coil center Mc4. The line connecting the first coil center Mc1 and the rotation axis Or when viewed from the axial direction Da is referred to as the first center line LM1. The line connecting the second coil center Mc2 and the rotation axis Or when viewed from the axial direction Da is referred to as the second center line LM2. The line connecting the third coil center Mc3 and the rotation axis Or when viewed from the axial direction Da is referred to as the third center line LM3. When viewed from the axial direction Da, a straight line connecting the fourth coil center Mc4 and the rotation axis Or is defined as a fourth center line LM4.

[0047] The distance in the circumferential direction Dc from the first coil center Mc1 to the end of the first receiving coil 31 facing the second receiving coil 32 is the same as the distance from the first coil center Mc1 to the end of the first receiving coil 31 opposite the second receiving coil 32. Therefore, the angle between the first center line LM1 and the first straight line L1 is the same as the angle between the first center line LM1 and the third straight line L3. Furthermore, the distance in the radial direction Dr from the first coil center Mc1 to the outer end of the first receiving coil 31 in the radial direction Dr is the same as the distance from the first coil center Mc1 to the inner end of the first receiving coil 31 in the radial direction Dr.

[0048] In addition, the distance in the circumferential direction Dc from the second coil center Mc2 to the end of the second receiving coil 32 on the first receiving coil 31 side is the same as the distance from the second coil center Mc2 to the end of the second receiving coil 32 opposite the first receiving coil 31. Therefore, the angle between the second center line LM2 and the second straight line L2 is the same as the angle between the second center line LM2 and the third straight line L3. Furthermore, in the radial direction Dr, the distance from the second coil center Mc2 to the outer end of the second receiving coil 32 in the radial direction Dr is the same as the distance from the second coil center Mc2 to the inner end of the second receiving coil 32 in the radial direction Dr.

[0049] In addition, the distance in the circumferential direction Dc from the third coil center Mc3 to the end of the third receiver coil 33 on the fourth receiver coil 34 side is the same as the distance from the third coil center Mc3 to the end of the third receiver coil 33 opposite the fourth receiver coil 34. Therefore, the angle formed by the third center line LM3 and the fourth straight line L4 is the same as the angle formed by the third center line LM3 and the sixth straight line L6. Furthermore, in the radial direction Dr, the distance from the third coil center Mc3 to the outer end of the third receiver coil 33 in the radial direction Dr is the same as the distance from the third coil center Mc3 to the inner end of the third receiver coil 33 in the radial direction Dr.

[0050] In addition, the distance in the circumferential direction Dc from the fourth coil center Mc4 to the end of the fourth receiver coil 34 on the third receiver coil 33 side is the same as the distance from the fourth coil center Mc4 to the end of the fourth receiver coil 34 opposite the third receiver coil 33. Therefore, the angle formed by the fourth center line LM4 and the fifth line L5 is the same as the angle formed by the fourth center line LM4 and the sixth line L6. Furthermore, in the radial direction Dr, the distance from the fourth coil center Mc4 to the outer end of the fourth receiver coil 34 in the radial direction Dr is the same as the distance from the fourth coil center Mc4 to the inner end of the fourth receiver coil 34 in the radial direction Dr.

[0051] Here, the angle formed by the first center line LM1 and the second center line LM2 is the first inter-coil angle θ12. The angle formed by the first center line LM1 and the third center line LM3 is the second inter-coil angle θ13. The angle formed by the first center line LM1 and the fourth center line LM4 is the third inter-coil angle θ14. Let n1, n2, and n3 be integers greater than or equal to 0.

[0052] The first inter-coil angle θ12 is an angle related to (n1 + 1 / 2) × α. The second inter-coil angle θ13 is an angle related to (n2 + 1 / 4) × α. The third inter-coil angle θ14 is an angle related to (n3 + 3 / 4) × α. Furthermore, n1, n2, and n3 are adjusted so that the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 do not overlap with one another. For example, n1 = 0, n2 = 1, and n3 = 1. Therefore, the first inter-coil angle θ12 is 1 / 2 × α. The second inter-coil angle θ13 is 5 / 4 × α. The third inter-coil angle θ14 is 7 / 4 × α.

[0053] Also, here, the convex portion 252 has a convex portion outer end 256 and a convex portion inner end 258. The first receiving coil 31 has a first coil outer end 316 and a first coil inner end 318. The second receiving coil 32 has a second coil outer end 326 and a second coil inner end 328. The third receiving coil 33 has a third coil outer end 336 and a third coil inner end 338. The fourth receiving coil 34 has a fourth coil outer end 346 and a fourth coil inner end 348.

[0054] The convex portion outer end 256 is the outer end of the convex portion 252 in the radial direction Dr. The convex portion inner end 258 is the inner end of the convex portion 252 in the radial direction Dr. The first coil outer end 316 is the outer end of the first receiving coil 31 in the radial direction Dr. The first coil inner end 318 is the inner end of the first receiving coil 31 in the radial direction Dr. The second coil outer end 326 is the outer end of the second receiving coil 32 in the radial direction Dr. The second coil inner end 328 is the inner end of the second receiving coil 32 in the radial direction Dr. The third coil outer end 336 is the outer end of the third receiving coil 33 in the radial direction Dr. The third coil inner end 338 is the inner end of the third receiving coil 33 in the radial direction Dr. The fourth coil outer end 346 is the outer end of the fourth receiving coil 34 in the radial direction Dr. The fourth coil inner end 348 is the inner end of the fourth receiving coil 34 in the radial direction Dr.

[0055] The first coil outer end 316, the second coil outer end 326, the third coil outer end 336, and the fourth coil outer end 346 are located outward in the radial direction Dr from the convex portion outer end 256. The first coil inner end 318, the second coil inner end 328, the third coil inner end 338, and the fourth coil inner end 348 are located inward in the radial direction Dr from the convex portion inner end 258.

[0056] The excitation coil 40 is formed on the substrate surface 300. Furthermore, the excitation coil 40 surrounds the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. Furthermore, as shown in Fig. 5, the excitation coil 40 is connected to an AC voltage generating circuit 45 mounted on the substrate 30 or outside the substrate 30. Furthermore, when an AC voltage from the AC voltage generating circuit 45 is applied to the excitation coil 40, the excitation coil 40 generates a magnetic field that passes through each of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34.

[0057] The detection unit 50 is mainly composed of a microcomputer and includes a CPU, ROM, flash memory, RAM, I / O, a detection circuit, and bus lines connecting these components. Furthermore, the detection unit 50 is disposed outside the substrate 30 as shown in Fig. 1. However, the detection unit 50 may also be disposed on the substrate 30.

[0058] As shown in FIG. 5 , the detection unit 50 is connected to the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. Furthermore, as described below, the detection unit 50 detects the rotation angle of the tire 12 based on the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. Furthermore, the detection unit 50 detects the displacement of the tire 12 in the vehicle width direction, i.e., the axial direction Da. As a result, the detection unit 50 detects the lateral force Fy of the tire 12. Furthermore, the detection unit 50 detects the displacement of the tire 12 in the radial direction Dr, for example, the vehicle height direction. As a result, the detection unit 50 detects the vertical load Fz of the tire 12. Furthermore, the detection unit 50 outputs signals corresponding to the detected rotation angle, lateral force Fy, and vertical load Fz to the inverter control device.

[0059] For example, as shown in FIG. 6 , the detection unit 50 includes a first operational amplifier 51, a second operational amplifier 52, a third operational amplifier 53, a fourth operational amplifier 54, a processing unit 60, a fifth operational amplifier 55, a sixth operational amplifier 56, an angle calculation unit 62, an adder 64, and a displacement calculation unit 66.

[0060] The first operational amplifier 51 is connected to one end and the other end of the first receiving coil 31. The first operational amplifier 51 also acquires the voltages at one end and the other end of the first receiving coil 31. The first operational amplifier 51 then outputs a signal corresponding to the voltage of the first receiving coil 31, based on the difference between these acquired voltages.

[0061] The second operational amplifier 52 is connected to one end and the other end of the second receiving coil 32. The second operational amplifier 52 also acquires the voltages at one end and the other end of the second receiving coil 32. The second operational amplifier 52 then outputs a signal corresponding to the voltage of the second receiving coil 32, based on the difference between these acquired voltages.

[0062] The third operational amplifier 53 is connected to one end and the other end of the third receiving coil 33. The third operational amplifier 53 also acquires the voltages at one end and the other end of the third receiving coil 33. The third operational amplifier 53 then outputs a signal corresponding to the voltage of the third receiving coil 33, based on the difference between these acquired voltages.

[0063] The fourth operational amplifier 54 is connected to one end and the other end of the fourth receiving coil 34. The fourth operational amplifier 54 also acquires the voltages at one end and the other end of the fourth receiving coil 34. The fourth operational amplifier 54 then outputs a signal corresponding to the voltage of the fourth receiving coil 34, based on the difference between these acquired voltages.

[0064] The processing unit 60 performs global line processing on the signals output from the first operational amplifier 51, the second operational amplifier 52, the third operational amplifier 53, and the fourth operational amplifier .

[0065] The fifth operational amplifier 55 is connected to the processing unit 60. The fifth operational amplifier 55 also acquires the voltages of the first receiving coil 31 and the second receiving coil 32 that have been subjected to the blanket processing. The fifth operational amplifier 55 also outputs a signal corresponding to the difference between the voltages of the first receiving coil 31 and the second receiving coil 32.

[0066] The sixth operational amplifier 56 is connected to the processing unit 60. The sixth operational amplifier 56 also acquires the voltages of the third receiving coil 33 and the fourth receiving coil 34 that have been subjected to the envelope processing. The sixth operational amplifier 56 also outputs a signal corresponding to the difference between the voltages of the third receiving coil 33 and the fourth receiving coil 34.

[0067] The angle calculation unit 62 is connected to the fifth operational amplifier 55 and the sixth operational amplifier 56. The angle calculation unit 62 also acquires a signal from the fifth operational amplifier 55 and a signal from the sixth operational amplifier 56. As will be described later, the angle calculation unit 62 further calculates the rotation angle of the target 25 based on these acquired signals. As a result, the angle calculation unit 62 calculates the rotation angle of the tire 12. Specifically, the angle calculation unit 62 calculates the rotation angle of the target 25 based on the voltage difference between the first receiving coil 31 and the second receiving coil 32 and the voltage difference between the third receiving coil 33 and the fourth receiving coil 34. As a result, the angle calculation unit 62 calculates the rotation angle of the tire 12. As a result, the detection unit 50 detects the rotation angle of the tire 12. The angle calculation unit 62 then outputs a signal corresponding to the calculated rotation angle to the inverter control device.

[0068] The adder 64 is connected to the processing unit 60. The adder 64 also acquires the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 that have been subjected to envelope processing. The adder 64 then outputs a signal corresponding to the sum of these acquired voltages, i.e., the sum of the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34.

[0069] The displacement calculation unit 66 is connected to the fifth operational amplifier 55, the sixth operational amplifier 56, and the adder 64. The displacement calculation unit 66 also acquires the signal from the fifth operational amplifier 55, the signal from the sixth operational amplifier 56, and the signal from the adder 64. The displacement calculation unit 66 further calculates the displacement of the target 25 in the axial direction Da based on the signal from the fifth operational amplifier 55, i.e., the voltage difference between the first receiving coil 31 and the second receiving coil 32 on which envelope processing has been performed. Alternatively, the displacement calculation unit 66 calculates the displacement of the target 25 in the axial direction Da based on the signal from the fifth operational amplifier 55, i.e., the voltage difference between the third receiving coil 33 and the fourth receiving coil 34 on which envelope processing has been performed. As a result, the displacement calculation unit 66 calculates the displacement of the tire 12 in the axial direction Da. As a result, the detection unit 50 detects the displacement of the tire 12 in the axial direction Da. Furthermore, the displacement calculation unit 66 calculates the displacement of the target 25 in the radial direction Dr based on the signal from the adder 64, i.e., the sum of the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 that have been subjected to envelope processing. In this way, the displacement calculation unit 66 calculates the displacement of the tire 12 in the radial direction Dr. In this way, the detection unit 50 detects the displacement of the tire 12 in the radial direction Dr.

[0070] The displacement calculation unit 66 also calculates the lateral force Fy based on the calculated displacement of the tire 12 in the axial direction Da, the mass of the tire 12, etc. As a result, the detection unit 50 detects the lateral force Fy. Furthermore, the displacement calculation unit 66 calculates the vertical load Fz based on the calculated displacement of the tire 12 in the radial direction Dr, the mass of the tire 12, etc. As a result, the detection unit 50 detects the vertical load Fz. The displacement calculation unit 66 then outputs a signal corresponding to the calculated lateral force Fy and vertical load Fz to the inverter control device.

[0071] The sensor device 20 of the first embodiment is configured as described above. Next, detection of the rotation angle of the tire 12, the displacement of the tire 12 in the axial direction Da, and the displacement of the tire 12 in the radial direction Dr by the sensor device 20 will be described. First, detection of the rotation angle of the tire 12 by the sensor device 20 will be described.

[0072] An AC voltage is applied from the AC voltage generating circuit 45 to the excitation coil 40. As a result, the excitation coil 40 generates a magnetic field that passes through each of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34.

[0073] Now, assume that the tire 12 rotates. Since the tire 12 is connected to the base portion 250 of the target 25 via the disk portion 102, the flat portion 146, and the flange portion 188, the target 25 rotates together with the tire 12.

[0074] At this time, since the target 25 is conductive, when the convex portion 252 faces the first receiving coil 31 in the axial direction Da, an eddy current is generated in the convex portion 252. This eddy current generates a magnetic field that passes through the first receiving coil 31. As a result, the first receiving coil 31 generates a voltage in a direction that cancels out the magnetic field caused by the eddy current and the magnetic field caused by the excitation coil 40.

[0075] As described above, the convex portions 252 and concave portions 254 are alternately arranged at intervals in the circumferential direction Dc. As a result, as the target 25 rotates, the magnitude of the portion of the magnetic field passing through the area surrounded by the first receiving coil 31 that faces the convex portions 252 changes periodically. Therefore, as the target 25 rotates, the voltage of the first receiving coil 31 changes periodically, as shown in FIG. 7 . Furthermore, after envelope processing, the voltage waveform of the first receiving coil 31 with respect to the rotation angle of the target 25 becomes sinusoidal, as shown in FIG. 8 . Furthermore, similar to the first receiving coil 31, voltages are generated in the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 as the target 25 rotates. The voltages of the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 change periodically. Furthermore, after envelope processing, the voltage waveforms of the second, third, and fourth receiving coils 32, 33, and 34 relative to the rotation angle of the target 25 become sine or cosine waveforms. Furthermore, here, the voltage waveform of the third receiving coil 33 relative to the rotation angle of the target 25 after envelope processing is sinusoidal. In FIG. 8 , the voltage of the first receiving coil 31 after envelope processing is indicated as V1. The voltage of the second receiving coil 32 after envelope processing is indicated as V2. The voltage of the third receiving coil 33 after envelope processing is indicated as V3. The voltage of the fourth receiving coil 34 after envelope processing is indicated as V4.

[0076] As described above, the angle θ12 between the first coils is set to α×½. Therefore, the phase difference between the voltage of the first receiving coil 31 and the voltage of the second receiving coil 32 is ½ period. Therefore, as shown in FIG. 9 , the voltage waveform of the difference between the voltages of the first receiving coil 31 and the second receiving coil 32, which has been subjected to envelope processing, with respect to the rotation angle of the target 25, also becomes sinusoidal. In FIG. 9 , the difference between the voltages of the first receiving coil 31 and the second receiving coil 32, which has been subjected to envelope processing, is shown as V1-V2.

[0077] Furthermore, as described above, the second inter-coil angle θ13 is 5 / 4 × α. Furthermore, the third inter-coil angle θ14 is 7 / 4 × α. Therefore, the angle between the third center line LM3 and the fourth center line LM4 is α × ½. Therefore, the phase difference between the voltages of the third receiving coil 33 and the fourth receiving coil 34 is ½ period. Therefore, the voltage waveform of the difference between the voltages of the third receiving coil 33 and the fourth receiving coil 34, which have been subjected to envelope processing, relative to the rotation angle of the target 25, also becomes sinusoidal. In FIG. 9, the difference between the voltages of the third receiving coil 33 and the fourth receiving coil 34, which have been subjected to envelope processing, is indicated as V3-V4.

[0078] Furthermore, because the second inter-coil angle θ13 is set to 5 / 4 × α, the phase difference between the voltage of the first receiving coil 31 and the voltage of the third receiving coil 33 is ¼ period. Therefore, the phase difference between the voltage difference between the envelope-processed first receiving coil 31 and the second receiving coil 32 and the voltage difference between the envelope-processed third receiving coil 33 and the fourth receiving coil 34 is ¼ period. Therefore, the voltage waveforms of the envelope-processed third receiving coil 33 and the fourth receiving coil 34 relative to the rotation angle of the target 25 are cosine waves.

[0079] Therefore, the detection unit 50 acquires the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. The detection unit 50 also performs envelope processing on these acquired voltages. The detection unit 50 then calculates the difference in voltage between the first receiving coil 31 and the second receiving coil 32 after envelope processing, and the difference in voltage between the third receiving coil 33 and the fourth receiving coil 34 after envelope processing. The detection unit 50 then divides the calculated difference in voltage between the first receiving coil 31 and the second receiving coil 32 by the difference in voltage between the third receiving coil 33 and the fourth receiving coil 34. The detection unit 50 then calculates the arctangent of this divided value. The detection unit 50 then calculates the rotation angle of the target 25 from the calculated arctangent value. In this way, the detection unit 50 detects the rotation angle of the target 25, thereby detecting the rotation angle of the tire 12.

[0080] Next, detection of displacement of the tire 12 in the axial direction Da will be described. As described above, the excitation coil 40 generates a magnetic field that passes through each of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34.

[0081] Now, assume that the tire 12 is displaced in the vehicle width direction, i.e., in the axial direction Da. Because the tire 12 is connected to the base portion 250 of the target 25 via the disk portion 102, the flat portion 146, and the flange portion 188, the target 25 is displaced in the axial direction Da.

[0082] As described above, the first inter-coil angle θ12 is set to α × ½. Therefore, for example, when the first coil center Mc1 is located on a line that passes through the center of the protrusion 252 and extends in the axial direction Da, the second coil center Mc2 is located on a line that passes through the center of the recess 254 and extends in the axial direction Da.

[0083] At this time, when the target 25 is displaced in the axial direction Da, the distance from the convex portion 252 to the first receiving coil 31 in the axial direction Da changes. As a result, the strength of the magnetic field passing through the first receiving coil 31 due to eddy currents changes. Therefore, at this time, the voltage of the first receiving coil 31 changes. Furthermore, when the target 25 is displaced in the axial direction Da, the distance from the concave portion 254 to the second receiving coil 32 in the axial direction Da changes. As a result, the voltage of the second receiving coil 32 does not change. Therefore, when the target 25 is displaced in the axial direction Da, the difference in voltage between the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing changes, as shown in FIG. 10 . Note that in FIG. 10 , the difference in voltage between the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing is shown as V1-V2.

[0084] Therefore, the detection unit 50 acquires the voltages of the first receiving coil 31 and the second receiving coil 32. The detection unit 50 also performs envelope processing on these acquired voltages. The detection unit 50 then calculates the difference between the voltages of the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing. The detection unit 50 then calculates the displacement of the target 25 in the axial direction Da from this calculated difference. As a result, the detection unit 50 detects the displacement of the target 25 in the axial direction Da. As a result, the detection unit 50 detects the displacement of the tire 12 in the axial direction Da. Note that here, the detection unit 50 calculates the displacement of the target 25 in the axial direction Da from the difference between the voltages of the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing. Alternatively, the detection unit 50 may calculate the displacement of the target 25 in the axial direction Da from the difference between the voltages of the third receiving coil 33 and the fourth receiving coil 34 that have been subjected to envelope processing. For example, the detection unit 50 may calculate the displacement of the target 25 in the axial direction Da from the difference between the two values, which has a larger absolute value.

[0085] Next, detection of displacement of the tire 12 in the radial direction Dr will be described. As described above, the excitation coil 40 generates a magnetic field that passes through each of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34.

[0086] Now, assume that the tire 12 is displaced in the radial direction Dr, for example, in the vehicle height direction. Since the tire 12 is connected to the base portion 250 of the target 25 via the disk portion 102, the flat portion 146, and the flange portion 188, the target 25 is displaced in the radial direction Dr.

[0087] When the target 25 is displaced in the radial direction Dr, the relative positions of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 with respect to the convex portion 252 change. This changes the strength of the magnetic field passing through each of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 due to eddy currents. Therefore, at this time, the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 change. Therefore, when the target 25 is displaced in the radial direction Dr, the sum of the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 that have been subjected to envelope processing changes, as shown in FIG. 11 . In FIG. 11, the sum of the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33 and the fourth receiving coil 34 that have been subjected to envelope processing is shown as V1+V2+V3+V4.

[0088] Therefore, the detection unit 50 acquires the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. The detection unit 50 also performs envelope processing on these acquired voltages. The detection unit 50 then calculates the sum of the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 that have been subjected to envelope processing. The detection unit 50 then calculates the displacement of the target 25 in the radial direction Dr from this calculated sum. In this way, the detection unit 50 detects the displacement of the target 25 in the radial direction Dr. In this way, the detection unit 50 detects the displacement of the tire 12 in the radial direction Dr.

[0089] As described above, the sensor device 20 detects the rotation angle of the tire 12, the displacement of the tire 12 in the axial direction Da, and the displacement of the tire 12 in the radial direction Dr.

[0090] Therefore, the sensor device 20 detects the rotation angle of the detection target as well as the displacement of the detection target. Specifically, the sensor device 20 includes a target 25, a first receiving coil 31, a second receiving coil 32, a third receiving coil 33, a fourth receiving coil 34, and a detection unit 50. The first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 are aligned in the circumferential direction Dc. The voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 are in different phases. The detection unit 50 detects the rotation angle and displacement of the detection target based on the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. Here, the detection unit 50 detects the rotation angle of the detection target based on a value related to the difference in voltage between the first receiving coil 31 and the second receiving coil 32 and a value related to the difference in voltage between the third receiving coil 33 and the fourth receiving coil 34. The detection unit 50 also detects displacement of the detection target in the axial direction Da based on a value related to the difference in voltage between the first receiving coil 31 and the second receiving coil 32 or a value related to the difference in voltage between the third receiving coil 33 and the fourth receiving coil 34. The detection unit 50 also detects displacement of the detection target in the radial direction Dr based on a value related to the sum of the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33 and the fourth receiving coil 34.

[0091] As a result, the rotation angle of the detection object is detected, and the displacement of the detection object is also detected.

[0092] Furthermore, the sensor device 20 of the first embodiment also provides the following effects.

[0093] [1-1] The first, second, third, and fourth receiver coils 31, 32, 33, and 34 face the protrusion 252 in the axial direction Da.

[0094] As a result, compared to when the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 are facing the convex portion 252 in the radial direction Dr, the portions directly facing the convex portion 252 are larger. This makes it easier for eddy currents to be generated in the convex portion 252. This makes it easier for magnetic fields passing through the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 to change. This makes it easier for voltages generated in the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 to change. This improves the sensitivity of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. This prevents a decrease in the detection accuracy of the rotation angle and displacement of the detection target.

[0095] [1-2] The first and second receiving coils 31 and 32 are formed so that the above-mentioned relational expression (1-1) is satisfied. The third and fourth receiving coils 33 and 34 are formed so that the above-mentioned relational expression (1-2) is satisfied.

[0096] As a result, when the convex portion 252 rotates, the area of ​​the portion of the convex portion 252 directly facing the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 is likely to change. As a result, the voltage waveforms of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 are likely to become sine waves or cosine waves. This makes it easier to detect the rotation angle of the detection target. As a result, a decrease in the detection accuracy of the rotation angle of the detection target is suppressed.

[0097] [1-3] The sensor device 20 further includes an excitation coil 40. When an AC voltage is applied to the excitation coil 40, the excitation coil 40 generates a magnetic field that passes through each of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34.

[0098] This eliminates the need for each of the first, second, third, and fourth receiver coils 31, 32, 33, and 34 to generate a magnetic field that passes through it. Therefore, compared to a case where the excitation coil 40 is not provided, it is possible to increase the number of turns that contribute to the voltages of the first, second, third, and fourth receiver coils 31, 32, 33, and 34 generated by the rotation of the convex portion 252. Increasing the number of turns improves the sensitivity of each of the first, second, third, and fourth receiver coils 31, 32, 33, and 34. This prevents a decrease in the detection accuracy of the rotation angle and displacement of the detection target.

[0099] [1-4] In the circumferential direction Dc, the distance from the first coil center Mc1 to the end of the first receiving coil 31 on the side of the second receiving coil 32 is the same as the distance from the first coil center Mc1 to the end of the first receiving coil 31 opposite to the second receiving coil 32. Furthermore, in the radial direction Dr, the distance from the first coil center Mc1 to the outer end of the first receiving coil 31 in the radial direction Dr is the same as the distance from the first coil center Mc1 to the inner end of the first receiving coil 31 in the radial direction Dr.

[0100] This tends to make the voltage of the first receiving coil 31 generated when the second receiving coil 32 side faces the convex portion 252 with respect to the first coil center Mc1 the same as the voltage of the first receiving coil 31 generated when the opposite side of the second receiving coil 32 faces the convex portion 252. This tends to make the voltage waveform of the first receiving coil 31 sine wave-like or cosine wave-like.

[0101] In addition, the distance in the circumferential direction Dc from the second coil center Mc2 to the end of the second receiving coil 32 on the first receiving coil 31 side is the same as the distance from the second coil center Mc2 to the end of the second receiving coil 32 opposite to the first receiving coil 31. Furthermore, in the radial direction Dr, the distance from the second coil center Mc2 to the outer end of the second receiving coil 32 in the radial direction Dr is the same as the distance from the second coil center Mc2 to the inner end of the second receiving coil 32 in the radial direction Dr.

[0102] As a result, the voltage waveform of the second receiving coil 32 tends to be sine wave or cosine wave, similar to the above.

[0103] In addition, the distance in the circumferential direction Dc from the third coil center Mc3 to the end of the third receiver coil 33 on the fourth receiver coil 34 side is the same as the distance from the third coil center Mc3 to the end of the third receiver coil 33 opposite to the fourth receiver coil 34. Furthermore, in the radial direction Dr, the distance from the third coil center Mc3 to the outer end of the third receiver coil 33 in the radial direction Dr is the same as the distance from the third coil center Mc3 to the inner end of the third receiver coil 33 in the radial direction Dr.

[0104] As a result, the voltage waveform of the third receiving coil 33 tends to be sine wave or cosine wave, similar to the above.

[0105] In addition, the distance in the circumferential direction Dc from the fourth coil center Mc4 to the end of the fourth receiving coil 34 on the third receiving coil 33 side is the same as the distance from the fourth coil center Mc4 to the end of the fourth receiving coil 34 opposite the third receiving coil 33. Furthermore, in the radial direction Dr, the distance from the fourth coil center Mc4 to the outer end of the fourth receiving coil 34 in the radial direction Dr is the same as the distance from the fourth coil center Mc4 to the inner end of the fourth receiving coil 34 in the radial direction Dr.

[0106] As a result, the voltage waveform of the fourth receiving coil 34 tends to be sine or cosine, as described above, making it easier to detect the rotation angle of the detection object. As a result, the detection accuracy of the rotation angle of the detection object is reduced.

[0107] [1-5] The first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 are formed in a spiral shape extending on a plane perpendicular to the rotation axis Or.

[0108] As a result, the voltage waveforms of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 are more likely to be sine or cosine waveforms than when each receiving coil has a multi-turn structure with the same diameter. This makes it easier to detect the rotation angle of the detection target. Therefore, a decrease in the detection accuracy of the rotation angle of the detection target is suppressed. Furthermore, compared to when the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 are formed with sine and cosine waveforms, the number of turns is greater. This increases the sensitivity of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. Therefore, even when the distance from the target 25 to each coil in the axial direction Da is relatively large, the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 output voltages with relatively high sensitivity.

[0109] [1-6] The first receiving coil 31 has a plurality of first linear portions 311. The second receiving coil 32 has a plurality of second linear portions 322. The third receiving coil 33 has a plurality of third linear portions 333. The fourth receiving coil 34 has a plurality of fourth linear portions 344. The first linear portions 311, the second linear portions 322, the third linear portions 333, and the fourth linear portions 344 are arranged at intervals in the axial direction Da.

[0110] This increases the inductance of each of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. This makes it easier for changes to occur in the voltages generated in each of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. This improves the sensitivity of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. This prevents a decrease in the detection accuracy of the rotation angle and displacement of the detection target.

[0111] [1-7] The convex portion 252 is formed in an arc shape centered on the rotation axis Or.

[0112] As a result, the rotational orbit of the convex portion 252 becomes annular, and the convex portion 252 is more likely to face the first, second, third, and fourth receiver coils 31, 32, 33, and 34 in the axial direction Da than if the convex portion 252 were not arc-shaped. This makes it easier for eddy currents to be generated in the convex portion 252. This makes it easier for changes to occur in the magnetic fields passing through each of the first, second, third, and fourth receiver coils 31, 32, 33, and 34. This improves the sensitivity of each of the second, third, and fourth receiver coils 32, 33, and 34 to the displacement of the detection target in the axial direction Da.

[0113] [1-8] The first receiving coil 31 has a plurality of first linear portions 311. The first linear portions 311 are arranged at intervals in the radial direction Dr and are formed in an arc shape centered on the rotation axis Or.

[0114] As a result, the shape of the first receiving coil 31 follows the rotational path of the convex portion 252. Therefore, when the convex portion 252 rotates, the areas of the portions of the convex portion 252 that directly face the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 become relatively large. This improves the sensitivity of the first receiving coil 31 to the displacement of the detection target in the axial direction Da.

[0115] Similarly to the above, the second receiving coil 32 has a plurality of second linear portions 322. Furthermore, the third receiving coil 33 has a plurality of third linear portions 333. Furthermore, the fourth receiving coil 34 has a plurality of fourth linear portions 344. The second linear portions 322, the third linear portions 333, and the fourth linear portions 344 are arranged at intervals in the radial direction Dr, and are formed in an arc shape centered on the rotation axis Or.

[0116] As a result, similarly to the above, the sensitivity of each of the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 to the displacement of the detection target in the axial direction Da is improved.

[0117] [1-9] The protrusion 252 protrudes from the base portion 250 in the axial direction Da.

[0118] As a result, the recessed portions 254 become conductive portions, and the magnetic field from outside the sensor device 20 passes through the recessed portions 254 instead of the protruding portions 252. Therefore, the protruding portions 252 are less susceptible to the magnetic field from outside the sensor device 20. Therefore, noise due to eddy currents generated in the protruding portions 252 is suppressed.

[0119] [1-10] The convex portion 252 has a convex portion outer end 256 and a convex portion inner end 258. The first receiving coil 31 has a first coil outer end 316 and a first coil inner end 318. The second receiving coil 32 has a second coil outer end 326 and a second coil inner end 328. The third receiving coil 33 has a third coil outer end 336 and a third coil inner end 338. The fourth receiving coil 34 has a fourth coil outer end 346 and a fourth coil inner end 348. The first coil outer end 316, the second coil outer end 326, the third coil outer end 336, and the fourth coil outer end 346 are located radially outward of the convex portion outer end 256 in the radial direction Dr. The first coil inner end 318, the second coil inner end 328, the third coil inner end 338 and the fourth coil inner end 348 are located radially inward in the radial direction Dr than the convex portion inner end 258.

[0120] As a result, when the detection target is displaced in the radial direction Dr, the area of ​​the portions of the convex portion 252 directly facing the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 is likely to change. Therefore, when the detection target is displaced in the radial direction Dr, changes are likely to occur in the magnetic fields passing through the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. Therefore, the sensitivity of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 is improved in detecting displacement in the radial direction Dr. Therefore, a decrease in the detection accuracy of displacement in the radial direction Dr is suppressed.

[0121] Second Embodiment In the second embodiment, as shown in Figures 12 and 13, the sensor device 20 does not include the third receiving coil 33 and the fourth receiving coil 34. The shape of the convex portion 252 is different from that of the first embodiment. The shapes of the first receiving coil 31 and the second receiving coil 32 are also different from those of the first embodiment. The processing of the detection unit 50 is also different from that of the first embodiment. Other than these, the second embodiment is the same as the first embodiment.

[0122] Here, when viewed from the axial direction Da, the angle formed by a straight line connecting one end of the convex portion 252 on the circumferential direction Dc side to the rotation axis Or and a straight line connecting the other end of the convex portion 252 on the circumferential direction Dc side to the rotation axis Or is defined as the convex portion angle θpc.

[0123] The convex portion 252 is formed so that the following relational expression (2-1) is satisfied. The first receiving coil 31 and the second receiving coil 32 are also formed so that the following relational expression (2-2) is satisfied. For example, the first coil angle θc1 is set to α×¼. The second coil angle θc2 is set to α×¼.

[0124] 1 / 4×α≦θpc<θce1, 1 / 4×α≦θpc<α (2-1) 1 / 4×α≦θc1<θce1, 1 / 4×α≦θc1<α 1 / 4×α≦θc2<θce1, 1 / 4×α≦θc2<α (2-2)

[0125] Furthermore, the first inter-coil angle θ12 is an angle related to (n+¼)×α, where n is an integer equal to or greater than 0. For example, n=0 here. Therefore, the first inter-coil angle θ12 is ¼×α.

[0126] Furthermore, the detection unit 50 detects the rotation angle of the tire 12, the displacement of the tire 12 in the axial direction Da, and the displacement of the tire 12 in the radial direction Dr based on the voltages of the first receiving coil 31 and the second receiving coil 32.

[0127] Here, the voltages of the first receiving coil 31 and the second receiving coil 32 correlate with the rotation angle of the target 25. Therefore, the detection unit 50 calculates the rotation angle of the target 25 using the voltages of the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing and the map. As a result, the detection unit 50 detects the rotation angle of the tire 12 by detecting the rotation angle of the target 25. Note that the map is set through experiments, simulations, etc. so that the rotation angle of the target 25 can be calculated. Furthermore, by adjusting the shape, size, and positional relationship of the first receiving coil 31 and the second receiving coil 32, the voltage waveform of the first receiving coil 31 that has been subjected to envelope processing becomes sinusoidal, and the voltage waveform of the second receiving coil 32 that has been subjected to envelope processing becomes cosine. In this case, the detection unit 50 may divide the voltage of the first receiving coil 31 that has undergone envelope processing by the voltage of the second receiving coil 32 that has undergone envelope processing, and calculate the rotation angle of the tire 12 from the arc tangent of the divided value.

[0128] Furthermore, as described above, when the tire 12 is displaced in the vehicle width direction, i.e., in the axial direction Da, the target 25 is displaced in the axial direction Da. At this time, similar to the first embodiment, the difference in voltage between the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing changes. Therefore, the detection unit 50 calculates the displacement of the target 25 in the axial direction Da from the difference in voltage between the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing. In this way, the detection unit 50 detects the displacement of the target 25 in the axial direction Da, thereby detecting the displacement of the tire 12 in the axial direction Da.

[0129] Furthermore, as described above, when the tire 12 is displaced in the radial direction Dr, for example, in the vehicle height direction, the target 25 is displaced in the radial direction Dr. At this time, similar to the first embodiment, the sum of the voltages of the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing changes. Therefore, the detection unit 50 calculates the displacement of the target 25 in the radial direction Dr from the sum of the voltages of the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing. In this way, the detection unit 50 detects the displacement of the target 25 in the radial direction Dr, thereby detecting the displacement of the tire 12 in the radial direction Dr.

[0130] The sensor device 20 of the second embodiment is configured as described above. The second embodiment also provides the same effects as the first embodiment. The second embodiment also provides the following effects.

[0131] [2] As described in Japanese Patent Application Laid-Open Publication No. 2008-275506, a bearing device is known that detects a wheel moment load, a translational load in the direction of the wheel axis, and the rotational speed of the wheel. In this bearing device, an inductance-type displacement sensor faces a target member that rotates with the wheel in a direction perpendicular to the wheel axis. The bearing device also includes four displacement sensors, which are arranged at equal intervals around the wheel axis. The target member has multiple grooves formed therein that are equally spaced around the wheel axis. Target protrusions are formed between adjacent grooves. Furthermore, since the number of grooves is even, the number of target protrusions is also even. Therefore, the phases of the voltages output from the four displacement sensors are all the same. As a result, the rotational speed cannot be uniquely determined from the voltages output from the four displacement sensors. Therefore, the bearing device described in Japanese Patent Application Laid-Open Publication No. 2008-275506 cannot detect the rotational speed of the wheel.

[0132] In contrast, in the sensor device 20 of this embodiment, the second receiving coil 32 outputs a voltage having a periodicity corresponding to the change in the magnetic field caused by the convex portion 252, and the voltage is out of phase with the voltage of the first receiving coil 31. This allows the rotation angle of the detection object to be uniquely determined, and the detection unit 50 can detect the rotation angle of the detection object based on the voltages of the first receiving coil 31 and the second receiving coil 32. As described above, the detection unit 50 can detect not only the rotation angle of the detection object but also the displacement of the detection object. Furthermore, since the second embodiment has fewer receiving coils than the first embodiment, the number of parts of the sensor device 20 can be reduced.

[0133] Third Embodiment In a third embodiment, as shown in Fig. 14, the shape of the target 25 is different from that of the first embodiment. Other than this, the third embodiment is similar to the first embodiment.

[0134] Specifically, instead of protruding in the axial direction Da, the protruding portion 252 protrudes from the base portion 250 in the radial direction Dr. In this case, the protruding portion inner end 258 corresponds to the boundary portion of the protruding portion 252 with the base portion 250. Furthermore, the recessed portion 254 is defined as a space formed between the adjacent protruding portions 252.

[0135] The sensor device 20 of the third embodiment is configured as described above. The third embodiment also provides the same effects as the first embodiment. The third embodiment also provides the following effects.

[0136] [3] Because the recess 254 forms a space, the magnetic field easily passes through the protrusion 252. This makes it easier for eddy currents to be generated in the protrusion 252. This makes it easier for the magnetic fields passing through the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 to change. This makes it easier for the voltages generated in the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 to change. In other words, the sensitivity of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 is improved. This prevents a decrease in the detection accuracy of the rotation angle and displacement of the detection target.

[0137] Fourth Embodiment The fourth embodiment differs from the second embodiment in the processing by the detection unit 50. The rest of the fourth embodiment is the same as the second embodiment.

[0138] Here, for example, assume that the tire 12 is displaced simultaneously in the axial direction Da and the radial direction Dr. At this time, the target 25 is displaced simultaneously in the axial direction Da and the radial direction Dr. Furthermore, the ratio of the voltage change in the first receiving coil 31 and the second receiving coil 32 due to the displacement of the target 25 in the axial direction Da to the voltage change in the first receiving coil 31 and the second receiving coil 32 due to the displacement of the target 25 in the radial direction Dr is different. Therefore, at this time, the difference in voltage between the first receiving coil 31 and the second receiving coil 32 includes a displacement component of the target 25 in the radial direction Dr. Furthermore, the sum of the voltages of the first receiving coil 31 and the second receiving coil 32 includes a displacement component of the target 25 in the axial direction Da.

[0139] Therefore, the detection unit 50 calculates the displacement of the target 25 in the axial direction Da using the sum of the voltages of the first receiving coil 31 and the second receiving coil 32, in addition to the difference in voltages between the first receiving coil 31 and the second receiving coil 32. The detection unit 50 also calculates the displacement of the target 25 in the radial direction Dr using the sum of the voltages of the first receiving coil 31 and the second receiving coil 32, in addition to the difference in voltages between the first receiving coil 31 and the second receiving coil 32.

[0140] Specifically, the detection unit 50 calculates each displacement using the difference and sum, a map, and interpolation processing such as a bilinear method. The map for calculating each displacement is set through experiments, simulations, or the like. For example, as shown in FIG. 15 , the map is set so that when each displacement is fixed, the difference decreases as the sum increases. Furthermore, the radial direction Dr displacement and the sum are fixed, and the difference increases as the axial direction Da displacement increases. Furthermore, the axial direction Da displacement and the sum are fixed, and the difference increases as the radial direction Dr displacement increases. In FIG. 15 , the difference between the voltages of the first receiving coil 31 and the second receiving coil 32 is shown as V1-V2. The sum of the voltages of the first receiving coil 31 and the second receiving coil 32 is shown as V1+V2. Furthermore, when the displacement in the radial direction Dr is fixed and there is a displacement in one direction along the axial direction Da, the relationship between V1-V2 and V1+V2 in the map is shown as +ΔDa. When the displacement in the radial direction Dr is fixed and there is no displacement in the axial direction Da, the relationship between V1-V2 and V1+V2 in the map is shown as ΔDa=0. When the displacement in the radial direction Dr is fixed and there is a displacement in the opposite direction to the one direction along the axial direction Da, the relationship between V1-V2 and V1+V2 in the map is shown as -ΔDa. When the displacement in the axial direction Da is fixed and there is a displacement in one direction along the radial direction Dr, the relationship between V1-V2 and V1+V2 in the map is shown as +ΔDr. When the displacement in the axial direction Da is fixed and there is no displacement in the radial direction Dr, the relationship between V1-V2 and V1+V2 in the map is shown as ΔDr=0. The relationship between V1-V2 and V1+V2 in the map when the displacement in the axial direction Da is fixed and there is a displacement in the opposite direction to one direction in the radial direction Dr is shown as -ΔDr.

[0141] The sensor device 20 of the fourth embodiment is configured as described above. The fourth embodiment also provides the same effects as the second embodiment. The fourth embodiment also provides the following effects.

[0142] [4] The detection unit 50 detects the displacement of the detection object in the axial direction Da and the displacement of the detection object in the radial direction Dr based on the difference in voltage between the first receiving coil 31 and the second receiving coil 32 and the sum of the voltages of the first receiving coil 31 and the second receiving coil 32.

[0143] This allows the detection of each displacement of the detection object in the axial direction Da and the radial direction Dr, taking into consideration each component of the displacement of the detection object, thereby suppressing a decrease in the detection accuracy of the displacement of the detection object.

[0144] Fifth Embodiment The fifth embodiment differs from the first embodiment in the processing by the detection unit 50. The rest of the fifth embodiment is the same as the first embodiment.

[0145] As described above, the second inter-coil angle θ13 is set to 5 / 4 × α. The third inter-coil angle θ14 is set to 7 / 4 × α. Furthermore, for example, when viewed from the axial direction Da, it is assumed that the center of the convex portion 252, the first coil center Mc1, and the rotation axis Or are located on the same line, or the center of the convex portion 252, the second coil center Mc2, and the rotation axis Or are located on the same line. In this case, the area of ​​the portion of the convex portion 252 directly facing the third receiving coil 33 in the axial direction Da is the same as the area of ​​the portion of the convex portion 252 directly facing the fourth receiving coil 34 in the axial direction Da.

[0146] Therefore, as shown in FIG. 16 , the absolute value of the voltage difference between the third receiving coil 33 and the fourth receiving coil 34 is below a threshold, for example, zero. Even if the tire 12 and the target 25 are displaced in the axial direction Da and the radial direction Dr, the voltage difference between the third receiving coil 33 and the fourth receiving coil 34 is below a threshold, for example, zero. As described above, the phase difference between the voltage difference between the first receiving coil 31 and the second receiving coil 32 after envelope processing and the voltage difference between the third receiving coil 33 and the fourth receiving coil 34 after envelope processing is ¼ period. Therefore, the absolute value of the voltage difference between the first receiving coil 31 and the second receiving coil 32 is maximized. In FIG. 16 , the voltage difference between the first receiving coil 31 and the second receiving coil 32 after envelope processing when there is no displacement in the axial direction Da is indicated by V1-V2 and a solid line. The voltage difference between the first and second receiving coils 31 and 32, which have undergone envelope processing when there is displacement in one direction in the axial direction Da, is indicated by V1-V2 and a dashed line. The voltage difference between the first and second receiving coils 31 and 32, which have undergone envelope processing when there is displacement in the opposite direction to the one direction in the axial direction Da, is indicated by V1-V2 and a dashed line. Furthermore, the rotation angles at which the absolute value of the voltage difference between the third and fourth receiving coils 33 and 34 is equal to or less than a threshold value are indicated as θa1 and θa2. Furthermore, the threshold value is not limited to zero. The threshold value is set by experiment, simulation, or the like so that the absolute value of the voltage difference between the first and second receiving coils 31 and 32 is maximized.

[0147] Therefore, the detection unit 50 detects the displacement of the tire 12 and the target 25 in the axial direction Da based on the voltage difference between the first receiving coil 31 and the second receiving coil 32 when the absolute value of the voltage difference between the third receiving coil 33 and the fourth receiving coil 34 is equal to or less than a threshold value. Note that the threshold value is, for example, zero. The detection unit 50 may also hold the displacement at this time for a certain period of time. This allows for accurate detection values ​​to be held.

[0148] Also, assume that the center of the convex portion 252, the third coil center Mc3, and the rotation axis Or are located on the same line when viewed from the axial direction Da, or the center of the convex portion 252, the fourth coil center Mc4, and the rotation axis Or are located on the same line. In this case, the area of ​​the portion of the convex portion 252 directly facing the first receiving coil 31 in the axial direction Da is the same as the area of ​​the portion of the convex portion 252 directly facing the second receiving coil 32 in the axial direction Da.

[0149] Therefore, at this time, the absolute value of the voltage difference between the first receiving coil 31 and the second receiving coil 32 is below a threshold, for example, zero. Furthermore, even if the tire 12 and the target 25 are displaced in the axial direction Da and the radial direction Dr, the voltage difference between the first receiving coil 31 and the second receiving coil 32 is below a threshold, for example, zero. Furthermore, as described above, the phase difference between the voltage difference between the first receiving coil 31 and the second receiving coil 32 after envelope processing and the voltage difference between the third receiving coil 33 and the fourth receiving coil 34 after envelope processing is ¼ period. Therefore, at this time, the absolute value of the voltage difference between the third receiving coil 33 and the fourth receiving coil 34 is maximized. In FIG. 16 , the voltage difference between the third receiving coil 33 and the fourth receiving coil 34 after envelope processing when there is no displacement in the axial direction Da is indicated by V3-V4 and a solid line. The voltage difference between the third and fourth receiving coils 33 and 34, which have undergone envelope processing when there is displacement in one direction in the axial direction Da, is indicated by V3-V4 and a dashed line. The voltage difference between the third and fourth receiving coils 33 and 34, which have undergone envelope processing when there is displacement in the opposite direction from the one direction in the axial direction Da, is indicated by V3-V4 and a dashed-dotted line. Furthermore, the rotation angles when the absolute value of the voltage difference between the first and second receiving coils 31 and 32 is equal to or less than a threshold value are indicated as θb1 and θb2. Furthermore, the threshold value is not limited to zero. The threshold value is set by experiment, simulation, or the like so that the absolute value of the voltage difference between the third and fourth receiving coils 33 and 34 is maximized.

[0150] Therefore, the detection unit 50 detects the displacement of the tire 12 and the target 25 in the axial direction Da based on the voltage difference between the third receiving coil 33 and the fourth receiving coil 34 when the absolute value of the voltage difference between the first receiving coil 31 and the second receiving coil 32 is equal to or less than the threshold value. The detection unit 50 may hold the displacement at this time for a certain period of time. This allows the detection value to be held with high accuracy.

[0151] The sensor device 20 of the fifth embodiment is configured as described above. The fifth embodiment also provides the same effects as the first embodiment. The fifth embodiment also provides the following effects.

[0152] [5] As described above, the displacement of the detection object in the axial direction Da is detected when the absolute value of each voltage difference is maximum. This prevents a decrease in the detection accuracy of the displacement of the detection object in the axial direction Da.

[0153] Sixth Embodiment In a sixth embodiment, the sensor device 20 does not include the excitation coil 40. Other than this, the sixth embodiment is similar to the first embodiment.

[0154] 17 , the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 are each connected to an AC voltage generating circuit 45. Furthermore, when an AC voltage from the AC voltage generating circuit 45 is applied to the first receiving coil 31, the first receiving coil 31 generates a magnetic field passing through the first receiving coil 31. Furthermore, when an AC voltage from the AC voltage generating circuit 45 is applied to the second receiving coil 32, the second receiving coil 32 generates a magnetic field passing through the second receiving coil 32. Furthermore, when an AC voltage from the AC voltage generating circuit 45 is applied to the third receiving coil 33, the third receiving coil 33 generates a magnetic field passing through the third receiving coil 33. Furthermore, when an AC voltage from the AC voltage generating circuit 45 is applied to the fourth receiving coil 34, the fourth receiving coil 34 generates a magnetic field passing through the fourth receiving coil 34.

[0155] The sensor device 20 of the sixth embodiment is configured as described above. The sixth embodiment also provides the same effects as the first embodiment.

[0156] 18 , the seventh embodiment differs from the first embodiment in the shapes of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. The shape of the detection unit 50 also differs from the first embodiment. Other than these, the seventh embodiment is the same as the first embodiment.

[0157] Specifically, the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 are connected in series. Here, one end of the first receiving coil 31 is connected in series with one end of the second receiving coil 32. The other end of the second receiving coil 32 is connected in series with one end of the third receiving coil 33. The other end of the third receiving coil 33 is connected in series with one end of the fourth receiving coil 34. In addition, here, the winding directions of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 are adjusted so that the direction of current flowing due to voltage generated as the target 25 rotates is the same.

[0158] The detection unit 50 has a seventh operational amplifier 57 instead of the adder 64. The seventh operational amplifier 57 is connected to the processing unit 60. The seventh operational amplifier 57 also acquires the voltage of the first receiving coil 31 and the voltage of the fourth receiving coil 34 that have been subjected to envelope processing. The seventh operational amplifier 57 also outputs a signal corresponding to the difference between the voltages of the first receiving coil 31 and the fourth receiving coil 34.

[0159] Furthermore, due to the series connection, the voltage difference between the first receiving coil 31 and the fourth receiving coil 34 corresponds to the sum of the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. Therefore, the displacement calculation unit 66 calculates the displacement of the target 25 in the radial direction Dr from the signal from the seventh operational amplifier 57, i.e., the voltage difference between the first receiving coil 31 and the fourth receiving coil 34. In this way, the displacement calculation unit 66 calculates the displacement of the tire 12 in the radial direction Dr.

[0160] The sensor device 20 of the seventh embodiment is configured as described above. The seventh embodiment also provides the same effects as the first embodiment. The seventh embodiment also provides the following effects.

[0161] [6] Here, when the displacement of the detection target in the radial direction Dr is small, the voltages generated in the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 are small. As a result, the sum of the voltages in the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 is small.

[0162] In contrast, in the sixth embodiment, the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 are connected in series. Furthermore, the detection unit 50 detects the displacement of the detection target in the radial direction Dr based on the difference in voltage between the first receiving coil 31 and the fourth receiving coil 34.

[0163] As a result, the difference in voltage between the first receiving coil 31 and the fourth receiving coil 34 corresponds to the sum of the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. Furthermore, the difference in voltage between the first receiving coil 31 and the fourth receiving coil 34 is an amplified value compared to when the sum of the voltages of the receiving coils is calculated. Therefore, compared to when the sum of the voltages of the receiving coils is calculated, it is easier to detect the displacement of the detection target in the radial direction Dr when the displacement of the detection target in the radial direction Dr is small.

[0164] 19, the eighth embodiment differs from the first embodiment in the arrangement of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. The rest of the eighth embodiment is the same as the first embodiment.

[0165] Specifically, the first inter-coil angle θ12 is an angle related to 3 / 4×α, the second inter-coil angle θ13 is an angle related to 6 / 4×α, and the third inter-coil angle θ14 is an angle related to 9 / 4×α.

[0166] Due to the above positional relationship, the phase difference between the voltage of the first receiving coil 31 and the voltage of the second receiving coil 32 is ¼ period. Furthermore, the phase difference between the voltage of the first receiving coil 31 and the voltage of the third receiving coil 33 is ½ period. Furthermore, the phase difference between the voltage of the second receiving coil 32 and the voltage of the fourth receiving coil 34 is ½ period. Furthermore, the phase difference between the voltage of the third receiving coil 33 and the voltage of the fourth receiving coil 34 is ¼ period. Therefore, the phase difference between the voltage difference between the envelope-processed first receiving coil 31 and the third receiving coil 33 and the voltage difference between the envelope-processed second receiving coil 32 and the fourth receiving coil 34 is ¼ period.

[0167] Therefore, the detection unit 50 divides the difference between the voltage of the first receiving coil 31 and the voltage of the third receiving coil 33, which have been subjected to envelope processing, by the difference between the voltage of the second receiving coil 32 and the voltage of the fourth receiving coil 34, which have been subjected to envelope processing. The detection unit 50 then calculates the arctangent obtained by this division. Furthermore, the detection unit 50 calculates the rotation angle of the target 25 from the value of this calculated arctangent. In this way, the detection unit 50 detects the rotation angle of the target 25, and thereby detects the rotation angle of the tire 12.

[0168] The detection unit 50 also detects the displacement of the target 25 and the tire 12 in the axial direction Da based on the difference between the voltage of the first receiving coil 31 and the voltage of the third receiving coil 33 after envelope processing. Alternatively, the detection unit 50 detects the displacement of the target 25 and the tire 12 in the axial direction Da based on the difference between the voltage of the second receiving coil 32 and the voltage of the fourth receiving coil 34 after envelope processing. Furthermore, the detection unit 50 detects the displacement of the target 25 and the tire 12 in the radial direction Dr based on the sum of the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 after envelope processing. Thus, the detection unit 50 detects the rotation angle of the detection target as well as the displacement of the detection target, similar to the first embodiment.

[0169] The sensor device 20 of the eighth embodiment is configured as described above. The eighth embodiment also provides the same effects as the first embodiment. The eighth embodiment also provides the following effects.

[0170] [7] In the eighth embodiment, the intervals in the circumferential direction Dc between the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, and the fourth receiver coil 34 are relatively wide. This allows the sizes of the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, and the fourth receiver coil 34 to be increased in the circumferential direction Dc. This allows the sensitivity of the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, and the fourth receiver coil 34 to be improved.

[0171] 20 , the ninth embodiment differs from the first embodiment in the arrangement of the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, and the fourth receiver coil 34. In addition, the number of convex portions 252 is an odd number. Furthermore, the processing of the detection unit 50 differs from the first embodiment. Other than these, the ninth embodiment is the same as the first embodiment.

[0172] Here, the angle formed by the third center line LM3 and the fourth center line LM4 is defined as a fourth inter-coil angle θ34.

[0173] Here, the first inter-coil angle θ12 is an angle related to ½×α, the second inter-coil angle θ13 is an angle related to 90°, the third inter-coil angle θ14 is an angle related to 90°+½×α, and the fourth inter-coil angle θ34 is an angle related to ½×α.

[0174] Since the second inter-coil angle θ13 is 90° and the number of protrusions 252 is odd, the phase difference between the voltage of the first receiving coil 31 and the voltage of the third receiving coil 33 is ¼ period. Therefore, the detection unit 50 detects the rotation angle and displacement of the detection target, similarly to the first embodiment.

[0175] In addition, due to the above positional relationship, the angle formed by the second center line LM2 and the fourth center line LM4 is an angle of 90°. Therefore, displacement of the detection target in one direction in the radial direction Dr corresponds to the sum of the voltages of the first receiving coil 31 and the second receiving coil 32. Furthermore, displacement of the detection target in the axial direction Da and in a direction perpendicular to the above direction corresponds to the sum of the voltages of the third receiving coil 33 and the fourth receiving coil 34.

[0176] Therefore, the detection unit 50 calculates the displacement of the detection target in one direction in the radial direction Dr based on the sum of the voltages of the first receiving coil 31 and the second receiving coil 32. The detection unit 50 also calculates the displacement of the detection target in the axial direction Da and in a direction perpendicular to the one direction based on the sum of the voltages of the third receiving coil 33 and the fourth receiving coil 34. The detection unit 50 also detects a vertical load Fz from the detected displacement of the tire 12 as the detection target in the one direction. The detection unit 50 also detects a longitudinal force of the tire 12 from the detected displacement of the tire 12 as the detection target in the axial direction Da and in a direction perpendicular to the one direction. The longitudinal force is a force acting between the ground G and the tire 12 in the longitudinal direction of the vehicle. The direction of the longitudinal force is also perpendicular to the directions of the lateral force Fy and the vertical load Fz.

[0177] The sensor device 20 of the ninth embodiment is configured as described above. The ninth embodiment also provides the same effects as the first embodiment. The ninth embodiment also provides the following effects.

[0178] [8] Due to the above positional relationship and the odd number of protrusions 252, the detection unit 50 can detect displacement of the detection object in one direction in the radial direction Dr, as well as in the axial direction Da and in a direction perpendicular to the above direction.

[0179] 21 , the tenth embodiment differs from the first embodiment in the arrangement of the first, second, third, and fourth receiver coils 31, 32, 33, and 34. The number of protrusions 252 is an odd number. Furthermore, the processing of the detection unit 50 differs from the first embodiment. Other than these, the tenth embodiment is the same as the first embodiment.

[0180] Specifically, the first inter-coil angle θ12 is an angle related to 3 / 4×α, the second inter-coil angle θ13 is an angle related to 180°, the third inter-coil angle θ14 is an angle related to 180°+3 / 4×α, and the fourth inter-coil angle θ34 is an angle related to 3 / 4×α.

[0181] Due to the above positional relationship, the phase difference between the voltage of the first receiving coil 31 and the voltage of the second receiving coil 32 is ¼ period. Furthermore, due to the above positional relationship and the fact that the number of convex portions 252 is odd, the phase difference between the voltage of the first receiving coil 31 and the voltage of the third receiving coil 33 is ½ period. Furthermore, the phase difference between the voltage of the second receiving coil 32 and the voltage of the fourth receiving coil 34 is ½ period. Furthermore, the phase difference between the voltage of the third receiving coil 33 and the fourth receiving coil 34 is ¼ period. Therefore, similar to the eighth embodiment, the detection unit 50 detects the rotation angle of the detection object and the displacement of the detection object in the radial direction Dr.

[0182] Here, when the target 25 is parallel to the radial direction Dr, i.e., when the tilt angle is 0°, the distances from the target 25 to the first, second, third, and fourth receiver coils 31, 32, 33, and 34 in the axial direction Da are the same. In this case, assume that the target 25 is displaced in the axial direction Da. At this time, since the distances are the same, the changes in the magnetic fields are also the same, and therefore the difference in voltage between the first and second receiver coils 31, 32 and the difference in voltage between the third and fourth receiver coils 33, 34 are the same.

[0183] In contrast, suppose the target 25 is tilted with respect to the radial direction Dr. In this case, the distance from the target 25 to the first and second receiver coils 31 and 32 in the axial direction Da is different from the distance from the target 25 to the third and fourth receiver coils 33 and 34. In this case, suppose the target 25 is displaced in the axial direction Da. At this time, since the distances are different, the changes in the magnetic fields are also different, and therefore the voltage difference between the first and second receiver coils 31 and 32 is different from the voltage difference between the third and fourth receiver coils 33 and 34. Therefore, the value obtained by subtracting the voltage difference between the third and fourth receiver coils 33 and 34 from the voltage difference between the first and second receiver coils 31 and 32 corresponds to the tilt angle of the target 25 with respect to the radial direction Dr. Furthermore, half of the sum of the displacements in the axial directions Da calculated from the above difference corresponds to the displacement of the target 25 in the axial direction Da, i.e., the displacement of the detection object in the axial direction Da.

[0184] Therefore, the detection unit 50 detects the tilt angle of the target 25 with respect to the radial direction Dr based on the difference in voltage between the first receiving coil 31 and the second receiving coil 32 and the difference in voltage between the third receiving coil 33 and the fourth receiving coil 34. The detection unit 50 also detects the displacement of the detection target in the axial direction Da based on the difference in voltage between the first receiving coil 31 and the second receiving coil 32 and the difference in voltage between the third receiving coil 33 and the fourth receiving coil 34.

[0185] Specifically, the detection unit 50 calculates a value obtained by subtracting the difference between the third receiving coil 33 and the fourth receiving coil 34 from the difference between the first receiving coil 31 and the second receiving coil 32. The detection unit 50 also calculates the tilt angle of the target 25 with respect to the radial direction Dr from this subtracted value. The detection unit 50 then calculates the displacement of the target 25 in the axial direction Da from half the sum of the displacements in each axial direction Da calculated from the above difference. In this way, the detection unit 50 calculates the displacement of the detection object in the axial direction Da. In this way, the detection unit 50 detects the tilt angle of the target 25 with respect to the radial direction Dr and the displacement of the detection object in the axial direction Da.

[0186] The sensor device 20 of the tenth embodiment is configured as described above. The tenth embodiment also provides the same effects as the first embodiment. The tenth embodiment also provides the following effects.

[0187] [9] Due to the above positional relationship and the odd number of convex portions 252, the detection unit 50 can detect not only the displacement of the detection object in the axial direction Da, but also the inclination angle of the target 25 relative to the radial direction Dr.

[0188] 22 , the eleventh embodiment differs from the first embodiment in the arrangement of the first, second, third, and fourth receiver coils 31, 32, 33, and 34. The number of protrusions 252 is an even number. Furthermore, the processing of the detection unit 50 differs from the first embodiment. Other than these, the eleventh embodiment is the same as the first embodiment.

[0189] Specifically, the first inter-coil angle θ12 is an angle related to 3 / 4×α, the second inter-coil angle θ13 is an angle related to 180°+1 / 2×α, the third inter-coil angle θ14 is an angle related to 180°+5 / 4×α, and the fourth inter-coil angle θ34 is an angle related to 3 / 4×α.

[0190] Due to the above positional relationship, the phase difference between the voltage of the first receiving coil 31 and the voltage of the second receiving coil 32 is ¼ period. Furthermore, due to the above positional relationship and the fact that the number of convex portions 252 is an even number, the phase difference between the voltage of the first receiving coil 31 and the voltage of the third receiving coil 33 is ½ period. Furthermore, the phase difference between the voltage of the second receiving coil 32 and the voltage of the fourth receiving coil 34 is ½ period. Furthermore, the phase difference between the voltage of the third receiving coil 33 and the voltage of the fourth receiving coil 34 is ¼ period. Therefore, similar to the eighth and tenth embodiments, the detection unit 50 detects the rotation angle of the detection target and the displacement of the detection target in the radial direction Dr. Furthermore, similar to the tenth embodiment, the detection unit 50 detects the tilt angle of the target 25 with respect to the radial direction Dr and the displacement of the detection target in the axial direction Da.

[0191] The sensor device 20 of the eleventh embodiment is configured as described above. The eleventh embodiment also achieves the same effects as the first embodiment. Furthermore, in the eleventh embodiment, similar to the tenth embodiment, the detection unit 50 can detect the tilt angle of the target 25 with respect to the radial direction Dr and the displacement of the detection object in the axial direction Da.

[0192] 23 , the twelfth embodiment differs from the first embodiment in the arrangement of the first, second, third, and fourth receiver coils 31, 32, 33, and 34. The number of protrusions 252 is an odd number. Furthermore, the processing of the detection unit 50 differs from the first embodiment. Other than these, the twelfth embodiment is the same as the first embodiment.

[0193] Specifically, the first inter-coil angle θ12 is an angle related to 180°, the second inter-coil angle θ13 is an angle related to 90°, and the third inter-coil angle θ14 is an angle related to 270°.

[0194] Due to the above positional relationship and the odd number of protrusions 252, the phase difference between the voltage of the first receiving coil 31 and the voltage of the second receiving coil 32 is ½ period. Also, the phase difference between the voltage of the third receiving coil 33 and the voltage of the fourth receiving coil 34 is ½ period. Furthermore, the phase difference between the voltage of the first receiving coil 31 and the voltage of the third receiving coil 33 is ¼ period. Also, the phase difference between the voltage of the second receiving coil 32 and the voltage of the fourth receiving coil 34 is ½ period. Therefore, the detection unit 50 detects the rotation angle of the detection target, similarly to the first embodiment.

[0195] As described above, when the target 25 is displaced in the axial direction Da, the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 change. Therefore, the displacement of the detection target in the axial direction Da can be obtained from the changes in these voltages.

[0196] Furthermore, as described above, when the target 25 is inclined with respect to the radial direction Dr, if the target 25 is displaced in the axial direction Da, the distances change, and therefore the changes in the magnetic fields also change. Therefore, the amount of change in voltage of the first receiving coil 31 differs from the amount of change in voltage of the second receiving coil 32. Furthermore, the amount of change in voltage of the third receiving coil 33 differs from the amount of change in voltage of the fourth receiving coil 34.

[0197] Furthermore, due to the above positional relationship, the value obtained by subtracting the amount of change in voltage of the second receiving coil 32 from the amount of change in voltage of the first receiving coil 31 corresponds to the tilt angle of the target 25 with respect to one direction, the radial direction Dr. Also, half the sum of the axial displacement in Da calculated from the amount of change in voltage of the first receiving coil 31 and the axial displacement in Da calculated from the amount of change in voltage of the second receiving coil 32 corresponds to the displacement of the target 25 in the axial direction Da. Also, the value obtained by subtracting the amount of change in voltage of the fourth receiving coil 34 from the amount of change in voltage of the third receiving coil 33 corresponds to the tilt angle of the target 25 with respect to the axial direction Da and the direction perpendicular to the one direction. Also, half the sum of the axial displacement in Da calculated from the amount of change in voltage of the third receiving coil 33 and the axial displacement in Da calculated from the amount of change in voltage of the fourth receiving coil 34 corresponds to the displacement of the target 25 in the axial direction Da.

[0198] Therefore, based on the above-mentioned change amount, the detection unit 50 detects not only the displacement of the detection target in the axial direction Da but also the tilt angle of the target 25 with respect to one direction in the radial direction Dr and the tilt angle of the target 25 with respect to the direction perpendicular to the axial direction Da and the one direction. Note that the above-mentioned change amount is the difference between the voltage of the first receiving coil 31 at the current time and the voltage of the first receiving coil 31 at a time prior to the current time. Also, the above-mentioned change amount is the difference between the voltage of the second receiving coil 32 at the current time and the voltage of the second receiving coil 32 at a time prior to the current time. Furthermore, the above-mentioned change amount is the difference between the voltage of the third receiving coil 33 at the current time and the voltage of the third receiving coil 33 at a time prior to the current time. Also, the above-mentioned change amount is the difference between the voltage of the fourth receiving coil 34 at the current time and the voltage of the fourth receiving coil 34 at a time prior to the current time.

[0199] Furthermore, when the target 25 is displaced in one direction in the radial direction Dr, for example, in the direction from the second receiving coil 32 toward the first receiving coil 31, the voltages of the first receiving coil 31 and the second receiving coil 32 change. Furthermore, as described above, the phase difference between the voltage of the first receiving coil 31 and the voltage of the second receiving coil 32 is ½ period. Therefore, when the target 25 is displaced in one direction in the radial direction Dr, the difference in voltage between the first receiving coil 31 and the second receiving coil 32 becomes larger than the voltages of the first receiving coil 31 and the second receiving coil 32. Therefore, by using the difference in voltage between the first receiving coil 31 and the second receiving coil 32, it is possible to accurately detect the displacement of the detection target in one direction in the radial direction Dr.

[0200] Furthermore, when the target 25 is displaced in a direction perpendicular to the axial direction Da and the above-mentioned one direction, for example, in a direction from the third receiving coil 33 to the fourth receiving coil 34, the voltages of the first receiving coil 31 and the second receiving coil 32 change. The phase difference between the voltage of the third receiving coil 33 and the voltage of the fourth receiving coil 34 is ½ period. Therefore, when the target 25 is displaced in a direction perpendicular to the axial direction Da and the above-mentioned one direction, the voltage difference between the third receiving coil 33 and the fourth receiving coil 34 becomes larger than the voltages of the third receiving coil 33 and the fourth receiving coil 34. Therefore, by using the voltage difference between the third receiving coil 33 and the fourth receiving coil 34, it is possible to accurately detect the displacement of the detection target in the direction perpendicular to the axial direction Da and the above-mentioned one direction.

[0201] Therefore, the detection unit 50 detects the displacement of the detection target in one direction, the radial direction Dr, based on the difference between the first receiving coil 31 and the second receiving coil 32. Furthermore, the detection unit 50 detects the displacement of the detection target in the axial direction Da and in a direction perpendicular to the one direction, based on the difference between the third receiving coil 33 and the fourth receiving coil 34.

[0202] The sensor device 20 of the twelfth embodiment is configured as described above. The twelfth embodiment also provides the same effects as the first embodiment. The twelfth embodiment also provides the following effects.

[0203] [10-1] Due to the above positional relationship and the odd number of protrusions 252, the detection unit 50 can detect the tilt angle of the target 25 with respect to one direction, the radial direction Dr, in addition to the rotation angle and each displacement of the detection target. The detection unit 50 can also detect the tilt angle of the target 25 with respect to the axial direction Da and a direction perpendicular to the above direction.

[0204] [10-2] The detection unit 50 detects the displacement of the detection object in one direction, the radial direction Dr, from a value with relatively high sensitivity by using the difference between the first receiving coil 31 and the second receiving coil 32. The detection unit 50 also detects the displacement of the detection object in the axial direction Da and in a direction orthogonal to the one direction, from a value with relatively high sensitivity by using the difference between the third receiving coil 33 and the fourth receiving coil 34. As a result, a decrease in the detection accuracy of the displacement of the detection object in the radial direction Dr is suppressed.

[0205] 24 , the thirteenth embodiment differs from the twelfth embodiment in the arrangement of the first, second, third, and fourth receiver coils 31, 32, 33, and 34. The number of protrusions 252 is an odd number. Furthermore, the processing of the detection unit 50 differs from the twelfth embodiment. Other than these, the thirteenth embodiment is the same as the twelfth embodiment.

[0206] Specifically, the first inter-coil angle θ12 is an angle related to 90°-3 / 4×α, the second inter-coil angle θ13 is an angle related to 90°, the third inter-coil angle θ14 is an angle related to 180°-3 / 4×α, and the fourth inter-coil angle θ34 is an angle related to 90°-3 / 4×α.

[0207] Due to the above positional relationship and the odd number of convex portions 252, the phase difference between the voltage of the first receiving coil 31 and the voltage of the second receiving coil 32 is ½ period. Also, the phase difference between the voltage of the third receiving coil 33 and the voltage of the fourth receiving coil 34 is ½ period. Furthermore, the phase difference between the voltage of the first receiving coil 31 and the voltage of the third receiving coil 33 is ¼ period. Also, the phase difference between the voltage of the second receiving coil 32 and the voltage of the fourth receiving coil 34 is ¼ period. Therefore, the detection unit 50 detects the rotation angle of the detection object, similar to the first and twelfth embodiments.

[0208] As in the twelfth embodiment, the detection unit 50 detects the tilt angle of the target 25 with respect to one direction, the radial direction Dr, from the voltages of the first receiving coil 31 and the fourth receiving coil 34. Furthermore, the detection unit 50 detects the tilt angle of the target 25 with respect to the axial direction Da and the direction orthogonal to the one direction, from the displacement in the axial direction Da calculated from the voltages of the first receiving coil 31 and the fourth receiving coil 34, and the voltages of the second receiving coil 32 and the third receiving coil 33.

[0209] The sensor device 20 of the thirteenth embodiment is configured as described above. The thirteenth embodiment also achieves the same effects as the twelfth embodiment. Furthermore, in the thirteenth embodiment, the size of the substrate 30 can be made smaller than in the twelfth embodiment. This prevents the sensor device 20 from becoming too large.

[0210] 25, the sensor device 20 in the fourteenth embodiment further includes a fifth receiver coil 35, a sixth receiver coil 36, a seventh receiver coil 37, and an eighth receiver coil 38. The arrangement of the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, and the fourth receiver coil 34 differs from that in the first embodiment. Furthermore, the number of convex portions 252 is an odd number. The processing of the detection unit 50 differs from that in the first embodiment. Other than these, the sensor device 20 is the same as that in the first embodiment.

[0211] The shapes and sizes of the fifth receiver coil 35, sixth receiver coil 36, seventh receiver coil 37, and eighth receiver coil 38 are similar to those of the first receiver coil 31, second receiver coil 32, third receiver coil 33, and fourth receiver coil 34. In addition, in the radial direction Dr, the outer ends of the fifth receiver coil 35, sixth receiver coil 36, seventh receiver coil 37, and eighth receiver coil 38 in the radial direction Dr are located outward in the radial direction Dr from the convex outer end 256. In addition, in the radial direction Dr, the inner ends of the fifth receiver coil 35, sixth receiver coil 36, seventh receiver coil 37, and eighth receiver coil 38 in the radial direction Dr are located inward in the radial direction Dr from the convex inner end 258.

[0212] The fifth receiving coil 35 corresponds to the fifth coil and is formed on the substrate surface 300. As a result, the fifth receiving coil 35 faces the convex portion 252 and the concave portion 254 in the axial direction Da. Therefore, the fifth receiving coil 35 outputs a voltage having a periodicity according to the change in the magnetic field caused by the convex portion 252. Furthermore, the fifth receiving coil 35 is aligned with the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 in the circumferential direction Dc.

[0213] The sixth receiving coil 36 corresponds to the sixth coil and is formed on the substrate surface 300. As a result, the sixth receiving coil 36 faces the convex portion 252 and the concave portion 254 in the axial direction Da. Therefore, the sixth receiving coil 36 outputs a voltage having a periodicity according to the change in the magnetic field caused by the convex portion 252. Furthermore, the sixth receiving coil 36 is aligned with the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, the fourth receiving coil 34, and the fifth receiving coil 35 in the circumferential direction Dc.

[0214] The seventh receiver coil 37 corresponds to the seventh coil and is formed on the substrate surface 300. As a result, the seventh receiver coil 37 faces the convex portion 252 and the concave portion 254 in the axial direction Da. Therefore, the seventh receiver coil 37 outputs a voltage having a periodicity according to the change in the magnetic field caused by the convex portion 252. Furthermore, the seventh receiver coil 37 is aligned in the circumferential direction Dc with the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, the fourth receiver coil 34, the fifth receiver coil 35, and the sixth receiver coil 36.

[0215] The eighth receiver coil 38 corresponds to the eighth coil and is formed on the substrate surface 300. As a result, the eighth receiver coil 38 faces the convex portion 252 and the concave portion 254 in the axial direction Da. Therefore, the eighth receiver coil 38 outputs a voltage having a periodicity according to the change in the magnetic field caused by the convex portion 252. Furthermore, the eighth receiver coil 38 is arranged in the circumferential direction Dc with the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, the fourth receiver coil 34, the fifth receiver coil 35, the sixth receiver coil 36, and the seventh receiver coil 37.

[0216] Here, the center of the fifth receiving coil 35 when viewed from the axial direction Da is referred to as the fifth coil center Mc5. The center of the sixth receiving coil 36 when viewed from the axial direction Da is referred to as the sixth coil center Mc6. The center of the seventh receiving coil 37 when viewed from the axial direction Da is referred to as the seventh coil center Mc7. The center of the eighth receiving coil 38 when viewed from the axial direction Da is referred to as the eighth coil center Mc8. The line connecting the fifth coil center Mc5 and the rotation axis Or is referred to as the fifth center line LM5. The line connecting the sixth coil center Mc6 and the rotation axis Or is referred to as the sixth center line LM6. The line connecting the seventh coil center Mc7 and the rotation axis Or is referred to as the seventh center line LM7. The line connecting the eighth coil center Mc8 and the rotation axis Or is referred to as the eighth center line LM8.

[0217] The angle formed by the first center line LM1 and the second center line LM2 is an angle related to 1 / 2×α. The angle formed by the first center line LM1 and the third center line LM3 is an angle related to 90°. The angle formed by the second center line LM2 and the fourth center line LM4 is an angle related to 90°. The angle formed by the first center line LM1 and the fifth center line LM5 is an angle related to 180°. The angle formed by the second center line LM2 and the sixth center line LM6 is an angle related to 180°. The angle formed by the first center line LM1 and the seventh center line LM7 is an angle related to 270°. The angle formed by the second center line LM2 and the eighth center line LM8 is an angle related to 270°.

[0218] Furthermore, due to the above positional relationship and the fact that the number of protrusions 252 is an odd number, the fifth receiving coil 35 outputs a voltage that is in phase with the voltage of the second receiving coil 32. The sixth receiving coil 36 outputs a voltage that is in phase with the voltage of the first receiving coil 31. The seventh receiving coil 37 outputs a voltage that is in phase with the voltage of the fourth receiving coil 34. The eighth receiving coil 38 outputs a voltage that is in phase with the voltage of the third receiving coil 33.

[0219] Furthermore, the detection unit 50 detects the rotation angle of the detection target, the displacement of the detection target in the axial direction Da, and the displacement of the detection target in the radial direction Dr based on the voltage of each receiving coil. The voltage of each receiving coil is the voltage of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, the fourth receiving coil 34, the fifth receiving coil 35, the sixth receiving coil 36, the seventh receiving coil 37, and the eighth receiving coil 38.

[0220] As in the tenth embodiment, the detection unit 50 detects the tilt angle of the target 25 with respect to one direction, the radial direction Dr, based on the difference in voltage between the first receiving coil 31 and the second receiving coil 32 and the difference in voltage between the fifth receiving coil 35 and the sixth receiving coil 36. Furthermore, the detection unit 50 detects the tilt angle of the target 25 with respect to the axial direction Da and the direction orthogonal to the one direction, based on the difference in voltage between the third receiving coil 33 and the fourth receiving coil 34 and the difference in voltage between the seventh receiving coil 37 and the eighth receiving coil 38.

[0221] The sensor device 20 of the fourteenth embodiment is configured as described above. The fourteenth embodiment also provides the same effects as the first embodiment. The fourteenth embodiment also provides the following effects.

[0222]

[11] The detection unit 50 detects the rotation angle, displacements, and tilt angles of the detection target based on the voltages of the receiving coils. This allows the rotation angle, displacements, and tilt angles of the detection target to be detected with high accuracy.

[0223] 26 , the 15th embodiment differs from the 14th embodiment in the positional relationship between the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, the fourth receiver coil 34, the fifth receiver coil 35, the sixth receiver coil 36, the seventh receiver coil 37, and the eighth receiver coil 38. Other than this, the 15th embodiment is the same as the 14th embodiment.

[0224] Specifically, the angle formed by the first center line LM1 and the second center line LM2 is an angle related to 3 / 4 × α. The angle formed by the first center line LM1 and the third center line LM3 is an angle related to 90°. The angle formed by the first center line LM1 and the fourth center line LM4 is an angle related to 180°. The angle formed by the first center line LM1 and the fifth center line LM5 is an angle related to 270°. The angle formed by the second center line LM2 and the sixth center line LM6 is an angle related to 90°. The angle formed by the second center line LM2 and the eighth center line LM8 is an angle related to 180°. The angle formed by the second center line LM2 and the seventh center line LM7 is an angle related to 270°.

[0225] Furthermore, due to the above positional relationship and the odd number of convex portions 252, the fifth receiving coil 35 outputs a voltage that is in phase with the voltage of the second receiving coil 32. The sixth receiving coil 36 outputs a voltage that is in phase with the voltage of the first receiving coil 31. The seventh receiving coil 37 outputs a voltage that is in phase with the voltage of the fourth receiving coil 34. The eighth receiving coil 38 outputs a voltage that is in phase with the voltage of the third receiving coil 33. Therefore, the detection unit 50 detects the rotation angle, each displacement, and tilt angle of the detection object, similarly to the fourteenth embodiment.

[0226] The sensor device 20 of the fifteenth embodiment is configured as described above. The fifteenth embodiment also achieves the same effects as the fourteenth embodiment. Furthermore, in the fifteenth embodiment, the intervals between the receiver coils in the circumferential direction Dc are relatively wide. Therefore, the size of each receiver coil in the circumferential direction Dc can be increased. Therefore, the sensitivity of each receiver coil can be improved.

[0227] 27 , in the sixteenth embodiment, the shapes of the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, and the fourth receiver coil 34 are different from those in the first embodiment. In addition, the number of convex portions 252 is an odd number.

[0228] Specifically, the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, and the fourth receiver coil 34 are arranged further outward in the radial direction Dr than the convex portion 252. As a result, the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, and the fourth receiver coil 34 face the convex portion 252 in the radial direction Dr. Here, the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, and the fourth receiver coil 34 have a spiral shape extending on a plane perpendicular to the radial direction Dr.

[0229] The first inter-coil angle θ12 is an angle related to 180°, the second inter-coil angle θ13 is an angle related to 90°, and the third inter-coil angle θ14 is an angle related to 270°.

[0230] Furthermore, due to the above positional relationship and the odd number of protrusions 252, the phase difference between the voltage of the first receiving coil 31 and the voltage of the second receiving coil 32 is ½ period. Also, the phase difference between the voltage of the third receiving coil 33 and the voltage of the fourth receiving coil 34 is ½ period. Furthermore, the phase difference between the voltage of the first receiving coil 31 and the voltage of the third receiving coil 33 is ¼ period. Therefore, the detection unit 50 detects the rotation angle and each displacement of the detection target, similarly to the first embodiment.

[0231] The sensor device 20 of the sixteenth embodiment is configured as described above. The sixteenth embodiment also provides the same effects as the first embodiment.

[0232] 28 and 29 , the seventeenth embodiment differs from the second embodiment in the shapes of the convex portion 252, the first receiving coil 31, and the second receiving coil 32. The processing of the detection unit 50 also differs from the second embodiment. Other than these, the seventeenth embodiment is the same as the second embodiment.

[0233] Specifically, the convex portion outer end 256 is located radially inward in the radial direction Dr than the first coil outer end 316. Furthermore, the convex portion outer end 256 is located radially outward in the radial direction Dr than the second coil outer end 326. Therefore, the convex portion outer end 256 is located between the first coil outer end 316 and the second coil outer end 326 in the radial direction Dr. Furthermore, the convex portion inner end 258 is located radially inward in the radial direction Dr than the first coil inner end 318 and the second coil inner end 328. Furthermore, the distance from the convex portion outer end 256 to the convex portion inner end 258 in the radial direction Dr is greater than the distance from the first coil outer end 316 to the first coil inner end 318. Furthermore, the distance from the convex outer end 256 to the convex inner end 258 in the radial direction Dr is greater than the distance from the second coil outer end 326 to the second coil inner end 328 .

[0234] Here, the minimum distance in the radial direction Dr from the first coil outer end 316 to the second coil outer end 326 is defined as the outer end distance Lo. The minimum distance in the radial direction Dr from the convex portion inner end 258 to the second coil inner end 328 is defined as the inner end distance Li. The outer end distance Lo is equal to or greater than the inner end distance Li, i.e., Lo≧Li.

[0235] Further, here, the excitation coil 40 has an outer excitation end 400 and an inner excitation end 402. The outer excitation end 400 is the outer end of the excitation coil 40 in the radial direction Dr. The inner excitation end 402 is the inner end of the excitation coil 40 in the radial direction Dr.

[0236] The convex portion outer end 256 is located between the excitation outer end 400 and the second coil outer end 326 in the radial direction Dr. Furthermore, the convex portion inner end 258 is located between the excitation inner end 402 and the second coil inner end 328 in the radial direction Dr.

[0237] Assume that the protrusion 252 and the second receiving coil 32 are cut through the rotation axis Or and the second coil center Mc2. In this cross section, the distance from the second coil center Mc2 to the outer end 256 of the protrusion in the radial direction Dr is preferably the same as the distance from the second coil center Mc2 to the inner end 258 of the protrusion. Furthermore, assume that the target 25 is not displaced in the radial direction Dr. In this case, the positional relationship, size, and shape of the protrusion 252 and the second receiving coil 32 are adjusted so that the strength of the outer magnetic field (described later) and the strength of the inner magnetic field (described later) are the same in the cross section. The strength of the outer magnetic field is the strength of the magnetic field between the portion of the protrusion 252 that is outer in the radial direction Dr than the second coil center Mc2 and the portion of the second receiving coil 32 that is outer in the radial direction Dr than the second coil center Mc2. Furthermore, the strength of the inner magnetic field is the strength of the magnetic field between the part of the convex portion 252 that is radially inward from the second coil center Mc2 and the part of the second receiving coil 32 that is radially inward from the second coil center Mc2.

[0238] The sensor device 20 of the seventeenth embodiment is configured as described above. The seventeenth embodiment also provides the same effects as the second embodiment. The seventeenth embodiment also provides the following effects.

[0239] [12-1] As described in German Patent Application Publication No. 102016211832, a rotation angle sensor is known that includes two receiver coils arranged in a circumferential direction centered on the rotor axis, a transmitter coil, and a conductor that rotates with the rotor. In this rotation angle sensor, when a voltage is applied to the transmitter coil, a magnetic field that passes through the two receiver coils is generated, and eddy currents are generated in the conductor. The rotation angle of the rotor, which rotates with the conductor, is detected from changes in the voltage generated in the two receiver coils by this eddy current.

[0240] The voltages of two receiving coils in a sensor such as that described in this patent document may be used to detect not only the rotor's rotation angle but also the rotor's displacement in a direction parallel to the rotor's axis and in a direction perpendicular to the rotor's axis. In this case, when the rotor displaces in a direction parallel to the axis, a change in the voltages of the two receiving coils arranged circumferentially occurs depending on the relative positions of the two receiving coils and conductors. Also, when the rotor displaces in a direction perpendicular to the axis, a change in the voltages of the two receiving coils arranged circumferentially occurs depending on the relative positions of the two receiving coils and conductors. However, in order to suppress a decrease in the detection accuracy of each displacement, there is a demand for a change in voltage to occur in one receiving coil but not in the other receiving coil when the rotor displaces in a direction perpendicular to the axis.

[0241] In contrast, in the sensor device 20 of the seventeenth embodiment, the convex outer end 256 is located radially inward in the radial direction Dr relative to the first coil outer end 316. Furthermore, the convex outer end 256 is located radially outward in the radial direction Dr relative to the second coil outer end 326. Furthermore, the convex inner end 258 is located radially inward in the radial direction Dr relative to the first coil inner end 318 and the second coil inner end 328. Furthermore, the distance Lo between the outer ends is equal to or greater than the distance Li between the inner ends. Assume that the convex portion 252 and the second receiving coil 32 are cut through the rotation axis Or and the second coil center Mc2. In this cross section, the distance from the second coil center Mc2 to the convex outer end 256 in the radial direction Dr is preferably the same as the distance from the second coil center Mc2 to the convex inner end 258.

[0242] 30 , for example, when the target 25 is displaced inward in the radial direction Dr, the area of ​​the portion of the target 25 that is outward in the radial direction Dr relative to the second coil center Mc2 decreases. As a result, the strength of the magnetic field generated by the eddy current in the target 25 and passing through the second coil outer end 326 decreases. Also, at this time, the area of ​​the portion of the target 25 that is outward in the radial direction Dr relative to the second coil center Mc2 increases. As a result, the strength of the magnetic field generated by the eddy current in the target 25 and passing through the second coil inner end 328 increases.

[0243] In contrast, the positional relationship between the convex portion 252, the first receiving coil 31, and the second receiving coil 32 tends to make the decrease in the magnetic field strength equal to the increase in the magnetic field strength. As a result, the decrease and increase in the magnetic field cancel each other out, so the overall strength of the magnetic field generated by the eddy currents in the target 25 and passing through the second receiving coil 32 tends to be the same as before the target 25 was displaced in the radial direction Dr. Therefore, as shown in FIG. 31 , fluctuations in the voltage of the second receiving coil 32 when the target 25 is displaced in the radial direction Dr are suppressed. Therefore, the sensor device 20 can suppress a decrease in the detection accuracy of the displacement of the detection target in the axial direction Da and the radial direction Dr. Note that FIG. 31 also shows, as a comparative example, the relationship between the amount of displacement in the radial direction Dr and the amount of change in the voltage of the receiving coil when using a rotation angle sensor such as that described in German Patent Application Publication No. 102016211832. Further, the amount of displacement in the radial direction Dr and the amount of change in the voltage of the second receiving coil 32 in the sensor device 20 of the seventeenth embodiment are shown as the present embodiment.

[0244] [12-2] The convex outer end 256 is located in the radial direction Dr between the excitation outer end 400 and the second coil outer end 326. Furthermore, the convex inner end 258 is located in the radial direction Dr between the excitation inner end 402 and the second coil inner end 328.

[0245] As a result, similar to the above, the decrease in the strength of the magnetic field tends to be equal to the increase in the strength of the magnetic field when the target 25 is displaced in the radial direction Dr. Therefore, similar to the above, fluctuations in the voltage of the second receiving coil 32 when the target 25 is displaced in the radial direction Dr are suppressed.

[0246] 18th Embodiment In the 18th embodiment, as shown in Fig. 32, the shape of the second receiving coil 32 is different from that of the 17th embodiment. Other than this, the 18th embodiment is the same as the 17th embodiment.

[0247] Specifically, the second receiving coil 32 has an outer linear portion 323 and an inner linear portion 324. The outer linear portion 323 is located outside the second coil center Mc2 in the radial direction Dr, and multiple inner linear portions 324 are arranged in the radial direction Dr. The inner linear portions 324 are located inside the second coil center Mc2 in the radial direction Dr, and multiple inner linear portions 324 are arranged in the radial direction Dr. Furthermore, in this example, the portion of the second receiving coil 32 located outside the second coil center Mc2 in the radial direction Dr is larger than the portion of the second receiving coil 32 located inside the second coil center Mc2 in the radial direction Dr. Furthermore, the distance between adjacent outer linear portions 323 in the radial direction Dr is longer than the distance between adjacent inner linear portions 324. For this reason, the sensitivity of the portion of the second receiving coil 32 located radially outside the second coil center Mc2 is adjusted to be the same as the sensitivity of the portion of the second receiving coil 32 located radially inside the second coil center Mc2.

[0248] The sensor device 20 of the eighteenth embodiment is configured as described above. The eighteenth embodiment also provides the same effects as the seventeenth embodiment.

[0249] Nineteenth Embodiment The nineteenth embodiment differs from the second embodiment in the processing of the detection unit 50. The rest of the nineteenth embodiment is the same as the second embodiment.

[0250] Here, in the second embodiment, the detection unit 50 calculates the rotation angle of the target 25 from the voltages of the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing. The detection unit 50 also calculates the displacement of the target 25 in the radial direction Dr from the sum of the voltages of the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing. Furthermore, the sum of the voltages of the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing includes the voltages of the first receiving coil 31 and the second receiving coil 32. As a result, an amount related to the rotation angle of the target 25 may be superimposed on the calculated displacement of the target 25 in the radial direction Dr.

[0251] Therefore, a change in the rotation angle of the target 25 causes a change in the calculated displacement of the target 25 in the radial direction Dr. Furthermore, the strength of the magnetic field passing through the first receiving coil 31 and the second receiving coil 32 due to the eddy current in the convex portion 252 differs depending on the distance from the convex portion 252 to the first receiving coil 31 and the second receiving coil 32 in the axial direction Da. Therefore, the voltages of the first receiving coil 31 and the second receiving coil 32 differ depending on the distance from the convex portion 252 to the first receiving coil 31 and the second receiving coil 32 in the axial direction Da. Therefore, the calculated displacement of the target 25 in the radial direction Dr may differ depending on the distance from the convex portion 252 to the first receiving coil 31 and the second receiving coil 32 in the axial direction Da.

[0252] In contrast, in the nineteenth embodiment, the detection unit 50 calculates the sum of squares of the voltages of the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing. As a result, the detection unit 50 calculates a value related to the distance from the convex portion 252 in the axial direction Da to the first receiving coil 31 and the second receiving coil 32. The detection unit 50 also corrects the calculated displacement of the target 25 in the radial direction Dr based on this calculated sum of squares and the calculated rotation angle of the target 25. This takes into account the distance from the convex portion 252 in the axial direction Da to the first receiving coil 31 and the second receiving coil 32 and the rotation angle of the target 25, which affect the calculated displacement of the target 25 in the radial direction Dr.

[0253] For example, the detection unit 50 linearly approximates the calculated displacement of the target 25 in the radial direction Dr with respect to the calculated rotation angle for each section of the calculated rotation angle. Furthermore, the detection unit 50 calculates the displacement of the target 25 in the radial direction Dr using the linearly approximated displacement of the target 25 in the radial direction Dr, the calculated sum of squares, and a predetermined function such as a quadratic function. In this way, the detection unit 50 corrects the displacement of the target 25 in the radial direction Dr. Note that the predetermined function such as a quadratic function is set by experiment, simulation, or the like so that the displacement of the target 25 in the radial direction Dr is corrected from the linearly approximated displacement of the target 25 in the radial direction Dr and the calculated sum of squares.

[0254] The sensor device 20 of the 19th embodiment is configured as described above. The 19th embodiment also provides the same effects as the second embodiment. The 19th embodiment also provides the following effects.

[0255]

[13] The detection unit 50 calculates a value related to the rotation angle of the detection object and a value related to the displacement of the detection object in the radial direction Dr based on the voltages of the first receiving coil 31 and the second receiving coil 32. The detection unit 50 also corrects the calculated value related to the displacement of the detection object in the radial direction Dr based on the calculated value related to the rotation angle and a value related to the sum of the squares of the voltages of the first receiving coil 31 and the second receiving coil 32.

[0256] This allows for consideration of the distance from the convex portion 252 in the axial direction Da to the first receiving coil 31 and the second receiving coil 32, and the rotation angle of the detection target, which affect the calculated displacement of the detection target in the radial direction Dr. Therefore, the detection unit 50 can accurately detect the displacement of the detection target in the radial direction Dr.

[0257] Twentieth Embodiment In a twentieth embodiment, as shown in Fig. 33, a sensor device 20 does not include an exciting coil 40. Other than this, the sensor device 20 is the same as the seventeenth embodiment.

[0258] In this case, when the AC voltage from the AC voltage generating circuit 45 is applied to the first receiving coil 31, the first receiving coil 31 generates a magnetic field that passes through the first receiving coil 31. Furthermore, when the AC voltage from the AC voltage generating circuit 45 is applied to the second receiving coil 32, the second receiving coil 32 generates a magnetic field that passes through the second receiving coil 32. Furthermore, when the AC voltage from the AC voltage generating circuit 45 is applied to the third receiving coil 33, the third receiving coil 33 generates a magnetic field that passes through the third receiving coil 33. Furthermore, when the AC voltage from the AC voltage generating circuit 45 is applied to the fourth receiving coil 34, the fourth receiving coil 34 generates a magnetic field that passes through the fourth receiving coil 34.

[0259] The sensor device 20 of the twentieth embodiment is configured as described above. The twentieth embodiment also provides the same effects as the seventeenth embodiment.

[0260] 34 , the sensor device 20 includes two first receiving coils 31. The sensor device 20 also includes two second receiving coils 32. Other than this, the sensor device 20 is the same as the seventeenth embodiment.

[0261] The first receiving coil 31 and the two second receiving coils 32 are arranged alternately in the circumferential direction Dc. The winding direction of one first receiving coil 31 is different from the winding direction of the other first receiving coil 31. The winding direction of one second receiving coil 32 is different from the winding direction of the other second receiving coil 32.

[0262] The sensor device 20 of the 19th embodiment is configured as described above. The 19th embodiment also achieves the same effects as the 17th embodiment. While the 19th embodiment has two first receiver coils 31 and two second receiver coils 32 arranged in the circumferential direction Dc, the present invention is not limited to this. The number of first receiver coils 31 and two second receiver coils 32 arranged in the circumferential direction Dc may be three or more. Furthermore, the winding direction of one first receiver coil 31 may be the same as the winding direction of the other first receiver coil 31. Furthermore, the winding direction of one second receiver coil 32 may be the same as the winding direction of the other second receiver coil 32.

[0263] 35 , the sensor device 20 further includes two third receiving coils 33. The processing of the detection unit 50 differs from that of the 21st embodiment. Other than this, the sensor device 20 is the same as the 21st embodiment.

[0264] Here, the third receiving coils 33 output a voltage having a periodicity corresponding to the change in the magnetic field caused by the convex portions 252, and which is in phase with the voltage of the first receiving coils 31. Each third receiving coil 33 is aligned with its corresponding first receiving coil 31 in the radial direction Dr. Here, the first center line LM1 coincides with the third center line LM3. The third receiving coils 33 are aligned with the second receiving coils 32 in the circumferential direction Dc. Furthermore, the winding direction of one third receiving coil 33 is different from the winding direction of the other third receiving coil 33.

[0265] The detector 50 detects the rotation angle and each displacement of the detection object based on the voltages of the first receiver coil 31 , the second receiver coil 32 and the third receiver coil 33 .

[0266] The sensor device 20 of the 22nd embodiment is configured as described above. The 22nd embodiment also achieves the same effects as the 21st embodiment. Note that, while the number of third receiving coils 33 is two in the 22nd embodiment, this is not limited to this. The number of third receiving coils 33 may be three or more. Furthermore, the winding direction of one third receiving coil 33 may be the same as the winding direction of the other third receiving coil 33.

[0267] Twenty-Third Embodiment In the twenty-third embodiment, as shown in FIG. 36, the shapes of the first and second receiving coils 31 and 32 are different from those in the seventeenth embodiment.

[0268] Specifically, the first receiving coil 31 and the second receiving coil 32 are formed in a sine wave shape and a cosine wave shape extending on a plane perpendicular to the axial direction Da. Here, the first receiving coil 31 is formed in a sine wave shape, and the second receiving coil 32 is formed in a cosine wave shape.

[0269] As a result, the second receiving coil 32 outputs a voltage that has a periodicity according to the change in the magnetic field caused by the convex portion 252 and that is out of phase with the voltage of the first receiving coil 31. Therefore, the detection unit 50 detects the rotation angle and each displacement of the detection target, similarly to the seventeenth embodiment.

[0270] Here, when viewed from the axial direction Da, the angle formed by a line connecting one circumferential end of the first receiving coil 31 to the rotation axis Or and a line connecting the other circumferential end of the first receiving coil 31 to the rotation axis Or is defined as θ1. When viewed from the axial direction Da, the angle formed by a line connecting one circumferential end of the second receiving coil 32 to the rotation axis Or and a line connecting the other circumferential end of the second receiving coil 32 to the rotation axis Or is defined as θ2.

[0271] Here, θ1=θ2. The convex portion angle θpc is equal to or greater than ¼×α and less than θ1. The convex portion angle θpc is equal to or greater than ¼×α and less than θ2.

[0272] The sensor device 20 of the 23rd embodiment is configured as described above. The 23rd embodiment also provides the same effects as the 17th embodiment.

[0273] 37 , the sensor device 20 further includes a third receiving coil 33. The processing of the detection unit 50 differs from that of the 23rd embodiment. Other than this, the sensor device 20 is the same as the 23rd embodiment.

[0274] The third receiving coil 33 is formed in a sinusoidal shape extending on a plane perpendicular to the axial direction Da, similar to the shape of the first receiving coil 31. The third receiving coil 33 is also disposed more inward in the radial direction Dr than the first receiving coil 31.

[0275] The detector 50 detects the rotation angle and each displacement of the detection object based on the voltages of the first receiver coil 31 , the second receiver coil 32 and the third receiver coil 33 .

[0276] The sensor device 20 of the twenty-fourth embodiment is configured as described above. The twenty-fourth embodiment also provides the same effects as the twenty-third embodiment.

[0277] 25th Embodiment In the 25th embodiment, as shown in Fig. 38, the configuration and processing of the detection unit 50 are different from those in the first embodiment. Other than this, the 25th embodiment is similar to the first embodiment.

[0278] Specifically, the detection unit 50 includes a first operational amplifier 51, a second operational amplifier 52, a third operational amplifier 53, a fourth operational amplifier 54, a fifth operational amplifier 55, and a sixth operational amplifier 56. The detection unit 50 also includes a processing unit 60, a GOP correction unit 70, an AD conversion unit 72, an angle calculation unit 62, a displacement calculation unit 66, and a correction unit 74.

[0279] As described above, the first operational amplifier 51 outputs a signal corresponding to the voltage of the first receiving coil 31. The second operational amplifier 52 outputs a signal corresponding to the voltage of the second receiving coil 32. The third operational amplifier 53 outputs a signal corresponding to the voltage of the third receiving coil 33. The fourth operational amplifier 54 outputs a signal corresponding to the voltage of the fourth receiving coil 34. The fifth operational amplifier 55 outputs a signal corresponding to the difference in voltage between the first receiving coil 31 and the second receiving coil 32. The sixth operational amplifier 56 outputs a signal corresponding to the difference in voltage between the third receiving coil 33 and the fourth receiving coil 34.

[0280] Here, as shown in the following relational expression (3-1), the difference in voltage between the first receiving coil 31 and the second receiving coil 32 is defined as a first voltage difference ΔVc12. As shown in the following relational expression (3-2), the difference in voltage between the third receiving coil 33 and the fourth receiving coil 34 is defined as a second voltage difference ΔVc34.

[0281] ΔVc12=V1-V2...(3-1) ΔVc34=V3-V4...(3-2)

[0282] In this case, when the second voltage difference ΔVc34 is plotted against the first voltage difference ΔVc12, the waveform of the second voltage difference ΔVc34 against the first voltage difference ΔVc12 becomes a Lissajous figure, as shown in Fig. 39. Note that a Lissajous figure is a plane figure obtained by combining two simple harmonic motions that are orthogonal to each other.

[0283] Returning to FIG. 38, the processing unit 60 performs blanket line processing on the first voltage difference ΔVc12 and the second voltage difference ΔVc34.

[0284] The GOP correction unit 70 uses a mathematical optimization method to correct the first voltage difference ΔVc12 and the second voltage difference ΔVc34 that have been subjected to global curve processing by the processing unit 60. GOP stands for Gain Offset Phase. Furthermore, the mathematical optimization method is a calculation technique that uses mathematical techniques and algorithms to solve the problem of maximizing or minimizing a specific objective function under given constraints.

[0285] Specifically, the GOP correction unit 70 uses a mathematical optimization method to calculate A1, A2, B1, B2, and C in the following relational expressions (3-3) and (3-4). The GOP correction unit 70 also calculates X in the following relational expression (3-3) and Y in the following relational expression (3-4) from the calculated A1, A2, B1, B2, and C and the first voltage difference ΔVc12 and second voltage difference ΔVc34 that have been subjected to global line processing by the processing unit 60. In this way, the GOP correction unit 70 corrects the first voltage difference ΔVc12 and the second voltage difference ΔVc34, and also increases the accuracy of the rotation angle calculated by the angle calculation unit 62, which will be described later, compared to before correction.

[0286] X=(A1×ΔVc12+B1)+(A2×ΔVc34+B2)...(3-3) Y=C×{(A1×ΔVc12+B1)-(A2×ΔVc34+B2)}...(3-4)

[0287] In this case, when the calculated X versus Y is plotted, the waveform of X versus Y becomes circular, as shown in Figure 40. Therefore, the waveform of X versus time is a cosine wave. Furthermore, the waveform of Y versus time is a sine wave.

[0288] Returning to FIG. 38, the AD conversion section 72 converts the analog signals of X and Y calculated by the GOP correction section 70 into digital signals.

[0289] Since the waveform of X with respect to time is a cosine wave and the waveform of Y with respect to time is a sine wave, the angle calculation unit 62 substitutes the digital signals X and Y into the following relational expression (3-5). In this way, the angle calculation unit 62 calculates the rotation angle of the target 25. In this way, the detection unit 50 detects the rotation angle of the tire 12 that rotates together with the target 25. Then, the angle calculation unit 62 outputs a signal corresponding to the calculated rotation angle to the inverter control device and the correction unit 74, which will be described later. In the following relational expression (3-5), θrt is the rotation angle of the tire 12 and the target 25.

[0290] θrt=arctan(Y / X)...(3-5)

[0291] 41 , a direction parallel to the radial direction Dr and extending from the rotation axis Or toward the second and third receiver coils 32 and 33 is defined as Dr_a. A direction parallel to the radial direction Dr and extending from the second and third receiver coils 32 and 33 toward the rotation axis Or is defined as Dr_b.

[0292] Also, assume that the target 25 does not displace in the axial direction Da but displaces in the direction Dr_a. At this time, the eddy current changes as the position where the convex portion 252 and the first receiving coil 31 directly face each other changes, and thus the voltage of the first receiving coil 31 decreases, as shown in FIG. 42 . Furthermore, the eddy current changes as the position where the convex portion 252 and the second receiving coil 32 directly face each other changes, and thus the voltage of the second receiving coil 32 decreases. Furthermore, the eddy current changes as the position where the convex portion 252 and the third receiving coil 33 directly face each other changes, and thus the voltage of the third receiving coil 33 decreases. Furthermore, the eddy current changes as the position where the convex portion 252 and the fourth receiving coil 34 directly face each other changes, and thus the voltage of the fourth receiving coil 34 decreases. In FIG. 42 , the voltage of the first receiving coil 31 is indicated as V1, the voltage of the second receiving coil 32 is indicated as V2, and the voltage of the third receiving coil 33 is indicated as V3. The voltage of the fourth receiving coil 34 is shown as V4. The direction of the arrows shows the increase or decrease in the value. Furthermore, the size of the arrows shows the increase or decrease in the value.

[0293] Furthermore, the change in area of ​​the portion where the convex portion 252 and the second receiving coil 32 directly face each other is larger than the change in area of ​​the portion where the convex portion 252 and the first receiving coil 31 directly face each other. Therefore, the amount of decrease in voltage of the second receiving coil 32 is larger than the amount of decrease in voltage of the first receiving coil 31. Therefore, when the target 25 does not displace in the axial direction Da but displaces in the axial direction Dr_a, the first voltage difference ΔVc12 increases.

[0294] Furthermore, the change in area of ​​the portion where the convex portion 252 and the third receiving coil 33 directly face each other is larger than the change in area of ​​the portion where the convex portion 252 and the fourth receiving coil 34 directly face each other. Therefore, the amount of decrease in voltage of the third receiving coil 33 is larger than the amount of decrease in voltage of the fourth receiving coil 34. Therefore, when the target 25 does not displace in the axial direction Da but displaces in the axial direction Dr_a, the second voltage difference ΔVc34 decreases.

[0295] Therefore, when the target 25 is not displaced in the axial direction Da but is displaced in the axial direction Dr_a, the first voltage difference ΔVc12 increases and the second voltage difference ΔVc34 decreases, so that the change in X is small and Y increases.

[0296] Therefore, when the target 25 is not displaced in the axial direction Da but is displaced in the direction Dr_a, the waveform of Y relative to X changes from a circle to an ellipse with the value related to X as the minor axis and the value related to Y as the major axis, as shown in FIG.

[0297] Now, let us assume that the target 25 is displaced not in the axial direction Da but in the direction Dr_b. In this case, the displacement direction of the target 25 is opposite to the direction Dr_a, so the voltage of the first receiving coil 31 and the voltages of the second receiving coil 32, third receiving coil 33, and fourth receiving coil 34 increase as shown in FIG.

[0298] Furthermore, the change in area of ​​the portion where the convex portion 252 and the second receiving coil 32 directly face each other is larger than the change in area of ​​the portion where the convex portion 252 and the first receiving coil 31 directly face each other. Therefore, the increase in the voltage of the second receiving coil 32 is larger than the increase in the voltage of the first receiving coil 31. Therefore, when the target 25 does not displace in the axial direction Da but displaces in the axial direction Dr_b, the first voltage difference ΔVc12 decreases.

[0299] Furthermore, the change in area of ​​the portion where the convex portion 252 and the third receiving coil 33 directly face each other is larger than the change in area of ​​the portion where the convex portion 252 and the fourth receiving coil 34 directly face each other. Therefore, the increase in the voltage of the third receiving coil 33 is larger than the increase in the voltage of the fourth receiving coil 34. Therefore, when the target 25 does not displace in the axial direction Da but displaces in the axial direction Dr_b, the second voltage difference ΔVc34 increases.

[0300] Therefore, when the target 25 is not displaced in the axial direction Da but is displaced in the axial direction Dr_b, the first voltage difference ΔVc12 decreases and the second voltage difference ΔVc34 increases, so that the change in X is small and Y decreases.

[0301] Therefore, when the target 25 is displaced in the direction Dr_b without being displaced in the axial direction Da, the waveform of Y relative to X changes from a circle to an ellipse with the value related to X as the major axis and the value related to Y as the minor axis, as shown in Fig. 44. Therefore, the displacement of the target 25 in the radial direction Dr corresponds to the value related to Y.

[0302] Now, suppose that the target 25 is displaced in the axial direction Da without being displaced in the radial direction Dr. At this time, the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 all increase. Alternatively, the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 all decrease.

[0303] Therefore, when the target 25 is displaced in the axial direction Da without being displaced in the radial direction Dr, the waveform of Y relative to X remains circular as shown in Fig. 45. However, the radius of the circle calculated from X and Y changes. Therefore, the displacement of the target 25 in the axial direction Da corresponds to a value for X.

[0304] Therefore, returning to FIG. 38, the displacement calculation section 66 calculates values ​​relating to the ellipse based on X and Y converted into digital signals by the AD conversion section 72.

[0305] For example, the displacement calculation unit 66 calculates values ​​related to the ellipse using the least squares method. Specifically, the displacement calculation unit 66 calculates an approximation ellipse C_XY from X and Y using the following relational expression (3-6), as shown in FIG. 46 . Furthermore, the displacement calculation unit 66 calculates the major axis and minor axis of the calculated approximation ellipse C_XY. Note that in the following relational expression (3-6), i is a natural number. m is a natural number and is the number of X and Y calculated by the GOP correction unit 70. Xi is the i-th X. Yi is the i-th Y. a is the major axis or minor axis of the X-axis of the approximation ellipse C_XY, whose axes are X and Y. b is the major axis or minor axis of the Y-axis of the approximation ellipse C_XY, whose axes are X and Y.

[0306]

[0307] Then, the displacement calculation unit 66 calculates the displacement of the target 25 in the axial direction Da and the displacement of the target 25 in the radial direction Dr based on the calculated a and b and the radius of a circle calculated from X and Y when the target 25 is not displaced. Note that the radius of the circle calculated from X and Y when the target 25 is not displaced is set in advance through experiments, simulations, etc. In addition, in Figure 46, the circle calculated from X and Y when the target 25 is not displaced is indicated as C_ref.

[0308] Specifically, the displacement calculation unit 66 calculates the displacement of the target 25 in the axial direction Da by subtracting the radius of a circle calculated from X and Y when the target 25 is not displaced from the calculated a. In this way, the displacement calculation unit 66 calculates the displacement of the tire 12 in the axial direction Da.

[0309] Furthermore, the displacement calculation unit 66 calculates the displacement of the target 25 in the radial direction Dr by subtracting the radius of the circle calculated from X and Y when the target 25 is not displaced from the calculated b. In this way, the displacement calculation unit 66 calculates the displacement of the tire 12 in the radial direction Dr.

[0310] Furthermore, the displacement calculation unit 66 calculates Fy_bb corresponding to the lateral force Fy based on the calculated displacement of the tire 12 in the axial direction Da, the mass of the tire 12, etc. The displacement calculation unit 66 also calculates Fz_bb corresponding to the vertical load Fz based on the calculated displacement of the tire 12 in the radial direction Dr, the mass of the tire 12, etc. The displacement calculation unit 66 also outputs signals corresponding to the calculated Fy_bb and Fz_bb to a correction unit 74, which will be described later.

[0311] 38 , the corrector 74 corrects Fy_bb and Fz_bb based on the rotation angle calculated by the angle calculator 62 and Fy_bb and Fz_bb calculated by the displacement calculator 66. In this way, the corrector 74 calculates the lateral force Fy and the vertical load Fz.

[0312] Here, Fy_bb and Fz_bb may be superimposed with amounts related to the rotation angle of the target 25. Therefore, Fy_bb and Fz_bb change with changes in the rotation angle of the target 25. Furthermore, the amount of change in Fy_bb and Fz_bb differs depending on the range of the rotation angle.

[0313] For this reason, the correction unit 74 linearly approximates Fy_bb and Fz_bb with respect to the rotation angle for each section of the rotation angle calculated by the angle calculation unit 62. As a result, the correction unit 74 calculates Fy_b by correcting Fy_bb. Furthermore, the correction unit 74 calculates Fz_b by correcting Fz_bb. Note that Fy_b is the corrected value of Fy_bb. Fz_b is the corrected value of Fz_bb.

[0314] Furthermore, Fy_b and Fz_b may contain each other's components as noise.

[0315] Therefore, as shown in FIG. 47 , the correction unit 74 calculates the lateral force Fy using the calculated Fy_b and Fz_b and a preset Q-order function. Furthermore, as shown in FIG. 48 , the correction unit 74 calculates the vertical load Fz using the calculated Fy_b and Fz_b and a preset R-order function. This removes noise contained in Fy_b and Fz_b, thereby suppressing a decrease in the detection accuracy of the lateral force Fy and the vertical load Fz. Note that Q and R are natural numbers. The Q-order function is set through experiments, simulations, etc., so as to suppress a decrease in the detection accuracy of the lateral force Fy. Furthermore, the R-order function is set through experiments, simulations, etc., so as to suppress a decrease in the detection accuracy of the vertical load Fz.

[0316] The correction unit 74 then outputs a signal corresponding to the calculated lateral force Fy and vertical load Fz to the inverter control device.

[0317] As described above, the detection unit 50 of the sensor device 20 of the 25th embodiment is configured and performs processing. This 25th embodiment also achieves the same effects as the first embodiment. The 25th embodiment also achieves the effects described below.

[0318] [14-1] Here, the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 contain offset components. Furthermore, these offset components are relatively large. Therefore, it is difficult to perform AD conversion of the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 that correspond to the displacement of the detection target in the axial direction Da and the displacement of the detection target in the radial direction Dr.

[0319] Therefore, the displacement calculation unit 66 of the detection unit 50 detects the displacement of the detection object in the axial direction Da and the displacement of the detection object in the radial direction Dr based on the first voltage difference ΔVc12 and the second voltage difference ΔVc34.

[0320] As described above, the first voltage difference ΔVc12 is the difference in voltage between the first receiving coil 31 and the second receiving coil 32. As a result, the offset component included in the voltage of the first receiving coil 31 and the offset component included in the voltage of the second receiving coil 32 cancel out, thereby removing the offset component included in the voltage of the first receiving coil 31 and the second receiving coil 32. Furthermore, the second voltage difference ΔVc34 is the difference in voltage between the third receiving coil 33 and the fourth receiving coil 34. As a result, the offset component included in the voltage of the third receiving coil 33 and the offset component included in the voltage of the fourth receiving coil 34 cancel out, thereby removing the offset component included in the voltage of the third receiving coil 33 and the fourth receiving coil 34. This makes it easy to perform AD conversion when detecting the displacement of the detection target in the axial direction Da and the radial direction Dr.

[0321] [14-2] The angle calculation unit 62 of the detection unit 50 detects the rotation angle of the detection object based on the first voltage difference ΔVc12 and the second voltage difference ΔVc34. Furthermore, the displacement calculation unit 66 corrects the first voltage difference ΔVc12 and the second voltage difference ΔVc34 using a mathematical optimization method, thereby increasing the accuracy of the rotation angle compared to before correction. Furthermore, the displacement calculation unit 66 calculates values ​​related to an ellipse based on X and Y corresponding to the corrected first voltage difference ΔVc12 and second voltage difference ΔVc34. Furthermore, the displacement calculation unit 66 detects the displacement of the detection object in the axial direction Da and the radial direction Dr based on a and b corresponding to the major axis and minor axis of the calculated ellipse.

[0322] This makes it easier to extract the displacement of the detection target in the axial direction Da and the displacement of the detection target in the radial direction Dr. Therefore, a decrease in the detection accuracy of the displacement of the detection target in the axial direction Da and the displacement of the detection target in the radial direction Dr is suppressed.

[0323] Twenty-Sixth Embodiment In the twenty-sixth embodiment, the processing of the displacement calculation unit 66 of the detection unit 50 is different from that in the twenty-fifth embodiment. Other than this, the twenty-sixth embodiment is the same as the twenty-fifth embodiment.

[0324] As described above, the waveform of X with respect to time or rotation angle is a cosine wave. The waveform of Y with respect to time or rotation angle is a sine wave. Therefore, as shown in FIG. 49 , when the value of X is at its peak value, the value of Y is zero. Also, when the value of Y is at its peak value, the value of X is zero. Furthermore, the displacement of the target 25 in the axial direction Da corresponds to the value related to X. The displacement of the target 25 in the radial direction Dr corresponds to the value related to Y.

[0325] Therefore, the displacement calculation unit 66 calculates the displacement of the target 25 in the axial direction Da and the radial direction Dr based on the peak values ​​of X and Y with respect to time or rotation angle and the peak values ​​of X and Y when the target 25 is not displaced. Note that the peak values ​​of X and Y when the target 25 is not displaced are set in advance through experiments, simulations, etc. Also, in Figure 49, X with respect to time or rotation angle when the target 25 is not displaced is indicated as X_ref. Y with respect to time or rotation angle when the target 25 is not displaced is indicated as Y_ref.

[0326] Specifically, the displacement calculation unit 66 detects the peaks of X and Y converted into digital signals by the AD conversion unit 72. Furthermore, the displacement calculation unit 66 calculates the displacement of the target 25 in the axial direction Da by subtracting the peak value of X when the target 25 is not displaced from the peak value of X. In this way, the displacement calculation unit 66 calculates the displacement of the tire 12 in the axial direction Da.

[0327] Furthermore, the displacement calculation unit 66 calculates the displacement of the target 25 in the radial direction Dr by subtracting the peak value of Y when the target 25 is not displaced from the peak value of Y. In this way, the displacement calculation unit 66 calculates the displacement of the tire 12 in the radial direction Dr.

[0328] Furthermore, the displacement calculation unit 66 calculates Fy_bb corresponding to the lateral force Fy based on the calculated displacement of the tire 12 in the axial direction Da, the mass of the tire 12, etc. The displacement calculation unit 66 also calculates Fz_bb corresponding to the vertical load Fz based on the calculated displacement of the tire 12 in the radial direction Dr, the mass of the tire 12, etc. The displacement calculation unit 66 also outputs signals corresponding to the calculated Fy_bb and Fz_bb to the correction unit 74.

[0329] As described above, the displacement calculation unit 66 in the sensor device 20 of the 26th embodiment performs processing. The 26th embodiment also achieves the same effects as the 25th embodiment. The 26th embodiment also achieves the following effects.

[0330]

[15] The displacement calculation unit 66 detects the displacement of the detection object in the axial direction Da and the radial direction Dr based on the peak values ​​of X and Y with respect to time or rotation angle.

[0331] This allows the displacement of the detection object in the axial direction Da and the displacement of the detection object in the radial direction Dr to be detected relatively easily, thereby reducing the calculation load on the displacement calculation unit 66.

[0332] 50 and 51 , the 27th embodiment differs from the second embodiment in the configurations of the target 25, the first receiving coil 31, and the second receiving coil 32. Also, the detection of the displacement of the target 25 in the radial direction Dr and the axial direction Da by the detection unit 50 differs from the second embodiment. Furthermore, the detection unit 50 detects the tilt angle of the target 25 with respect to the radial direction Dr, in addition to detecting the rotation angle and displacement of the target 25. Other than these, the 27th embodiment is similar to the second embodiment.

[0333] Specifically, the convex portion 252 of the target 25 protrudes outward in the radial direction Dr from the base portion 250. In this case, the convex portion inner end 258 corresponds to the boundary portion of the convex portion 252 with the base portion 250. Furthermore, the concave portion 254 is a space formed between the convex portions 252 adjacent to each other.

[0334] The first coil inner end 318 is located further outward in the radial direction Dr than the second coil outer end 326 .

[0335] The convex portion outer end 256 is located in the radial direction Dr more inward than the first coil outer end 316. Furthermore, the convex portion outer end 256 is located in the radial direction Dr more outward than the second coil outer end 326.

[0336] The convex portion inner end 258 is located radially inward in the radial direction Dr than the second coil inner end 328 .

[0337] Here, when the target 25 is displaced in the radial direction Dr, the portion where the convex portion 252 and the first receiving coil 31 directly face each other changes, causing a change in the eddy current, and therefore a change in the voltage of the first receiving coil 31. Furthermore, when the target 25 is displaced in the radial direction Dr, the portion where the convex portion 252 and the second receiving coil 32 directly face each other does not change, causing no change in the eddy current, and therefore no change in the voltage of the second receiving coil 32.

[0338] Therefore, the detection unit 50 calculates the displacement of the target 25 in the radial direction Dr from the voltage of the first receiving coil 31 that has undergone envelope processing. In this way, the detection unit 50 detects the displacement of the target 25 in the radial direction Dr.

[0339] Furthermore, when the target 25 is displaced in the axial direction Da, the distance from the convex portion 252 to the first receiving coil 31 in the axial direction Da changes, and the distance from the convex portion 252 to the second receiving coil 32 in the axial direction Da changes. Therefore, when the target 25 is displaced in the axial direction Da, the voltages of the first receiving coil 31 and the second receiving coil 32 change. Furthermore, as described above, when the target 25 is displaced in the radial direction Dr, the voltage of the first receiving coil 31 changes.

[0340] Therefore, the detection unit 50 calculates the displacement of the target 25 in the axial direction Da from the voltage of the second receiving coil 32 that has undergone envelope processing. In this way, the detection unit 50 detects the displacement of the target 25 in the axial direction Da.

[0341] As described above, when the target 25 is displaced in the radial direction Dr, the voltage of the first receiving coil 31 changes, but the voltage of the second receiving coil 32 does not change. Furthermore, when the target 25 is displaced in the axial direction Da, the voltages of the first receiving coil 31 and the second receiving coil 32 change. For these reasons, the detection unit 50 may calculate the displacement of the target 25 in the radial direction Dr from the difference between the voltages of the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing, instead of the voltage of the first receiving coil 31 that has been subjected to envelope processing. Furthermore, the detection unit 50 may calculate the displacement of the target 25 in the axial direction Da from the sum of the voltages of the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing, instead of the voltage of the second receiving coil 32 that has been subjected to envelope processing.

[0342] Also, assume that the target 25 is tilted with respect to the radial direction Dr. In this case, the distance from the target 25 to the first receiving coil 31 and the distance from the target 25 to the second receiving coil 32 in the axial direction Da are different. In this case, assume that the target 25 is displaced in the axial direction Da. At this time, since the distances are different, the changes in the magnetic fields are also different, and therefore the voltage of the first receiving coil 31 and the voltage of the second receiving coil 32 are different. Therefore, the value obtained by subtracting the voltage of the second receiving coil 32 from the voltage of the first receiving coil 31 corresponds to the tilt angle of the target 25 with respect to the radial direction Dr.

[0343] Therefore, the detector 50 detects the tilt angle of the target 25 with respect to the radial direction Dr based on the voltages of the first receiving coil 31 and the second receiving coil 32 .

[0344] Specifically, the detection unit 50 calculates a value obtained by subtracting the voltage of the second receiving coil 32 from the voltage of the first receiving coil 31. Furthermore, the detection unit 50 calculates the tilt angle of the target 25 with respect to the radial direction Dr from this subtracted value.

[0345] The sensor device 20 of the 27th embodiment is configured as described above. The 27th embodiment also provides the same effects as the second embodiment. The 27th embodiment also provides the following effects.

[0346] [16-1] Here, for a sensor that detects a rotation angle as described in Patent Document 1, it is required to suppress a decrease in the detection accuracy of the rotation angle.

[0347] In contrast to this, in the twenty-seventh embodiment, the first coil inner end 318 is located further outward in the radial direction Dr than the second coil outer end 326 .

[0348] As a result, the first receiving coil 31 and the second receiving coil 32 are aligned in the radial direction Dr. Therefore, when the target 25 rotates, the convex portion 252 directly faces both the first receiving coil 31 and the second receiving coil 32. Therefore, when the target 25 rotates, the voltages of both the first receiving coil 31 and the second receiving coil 32 change. Therefore, when the target 25 rotates, the voltages of the first receiving coil 31 and the second receiving coil 32 are more likely to change compared to when the first receiving coil 31 and the second receiving coil 32 are aligned only in the circumferential direction Dc. In other words, the sensitivity of the first receiving coil 31 and the second receiving coil 32 is improved. This suppresses a decrease in the detection accuracy of the rotation angle of the detection target.

[0349] [16-2] The detector 50 detects the displacement of the detection object in the radial direction Dr and the displacement of the detection object in the axial direction Da based on the voltages of the first receiving coil 31 and the second receiving coil 32.

[0350] This allows the detection unit 50 to detect the displacement of the detection object in the radial direction Dr and the axial direction Da in addition to the rotation angle of the detection object.

[0351] [16-3] The detector 50 detects the tilt angle of the target 25 with respect to the radial direction Dr based on the value related to the difference in voltage between the first receiver coil 31 and the second receiver coil 32.

[0352] This makes it possible to detect the tilt angle of the target 25 relative to the radial direction Dr, and therefore the tilt angle of the detection object that is tilted together with the target 25 can be detected.

[0353] 52 , the shape of the target 25 in the 28th embodiment is different from that in the 27th embodiment. The positional relationship between the target 25, the first receiving coil 31, and the second receiving coil 32 is also different from that in the 27th embodiment. Furthermore, the detection of the displacement of the target 25 in the radial direction Dr and the axial direction Da by the detection unit 50 is different from that in the 27th embodiment. Other than these, the 28th embodiment is the same as the 27th embodiment.

[0354] Specifically, the convex portion 252 of the target 25 protrudes from the base portion 250 in the axial direction Da, instead of protruding in the radial direction Dr.

[0355] The convex outer end 256 is located radially outward of the first coil outer end 316 in the radial direction Dr.

[0356] The convex portion inner end 258 is located in the radial direction Dr more inward than the second coil outer end 326. The convex portion inner end 258 is also located in the radial direction Dr more outward than the second coil inner end 328.

[0357] In this case, when the target 25 is displaced in the radial direction Dr, the voltage of the first receiving coil 31 does not change, but the voltage of the second receiving coil 32 changes. Furthermore, when the target 25 is displaced in the axial direction Da, the voltages of the first receiving coil 31 and the second receiving coil 32 change.

[0358] Therefore, the detection unit 50 calculates the displacement of the target 25 in the radial direction Dr from the voltage of the second receiving coil 32 on which the envelope processing has been performed. The detection unit 50 also calculates the displacement of the target 25 in the axial direction Da from the voltage of the first receiving coil 31 on which the envelope processing has been performed. Note that the detection unit 50 may calculate the displacement of the target 25 in the radial direction Dr from the difference in the voltages of the first receiving coil 31 and the second receiving coil 32 on which the envelope processing has been performed, instead of the voltage of the second receiving coil 32 on which the envelope processing has been performed. Furthermore, the detection unit 50 may calculate the displacement of the target 25 in the axial direction Da from the sum of the voltages of the first receiving coil 31 and the second receiving coil 32 on which the envelope processing has been performed, instead of the voltage of the first receiving coil 31 on which the envelope processing has been performed.

[0359] The sensor device 20 of the 28th embodiment is configured as described above. The 28th embodiment also provides the same effects as the 27th embodiment.

[0360] 53, the 29th embodiment differs from the 27th embodiment in the shapes of the first receiver coil 31 and the second receiver coil 32. Other than this, the 29th embodiment is the same as the 27th embodiment.

[0361] Specifically, instead of being spirally shaped, the first receiving coil 31 and the second receiving coil 32 are formed in a sine wave and a cosine wave extending on a plane perpendicular to the axial direction Da. Here, the first receiving coil 31 is formed in a sine wave shape, and the second receiving coil 32 is formed in a cosine wave shape.

[0362] When viewed from the axial direction Da, a line connecting one circumferential end of the first receiving coil 31 to the rotation axis Or coincides with a line connecting one circumferential end of the second receiving coil 32 to the rotation axis Or. Furthermore, a line connecting the other circumferential end of the first receiving coil 31 to the rotation axis Or coincides with a line connecting the other circumferential end of the second receiving coil 32 to the rotation axis Or.

[0363] The sensor device 20 of the twenty-ninth embodiment is configured as described above. The twenty-ninth embodiment also provides the same effects as the twenty-seventh embodiment.

[0364] 54 and 55 , in the 30th embodiment, the sensor device 20 further includes a third receiving coil 33 and a fourth receiving coil 34. The 30th embodiment differs from the 27th embodiment in that the detection unit 50 detects the rotation angle of the target 25, the displacement of the target 25 in the radial direction Dr and the axial direction Da, and the tilt angle of the target 25 with respect to the radial direction Dr. Other than these, the sensor device 20 is the same as the 27th embodiment.

[0365] Specifically, the third receiving coil 33 is aligned in the circumferential direction Dc with the first receiving coil 31. Furthermore, the third receiving coil 33 outputs a voltage that is out of phase with the voltages of the first receiving coil 31 and the second receiving coil 32.

[0366] The fourth receiving coil 34 is aligned in the circumferential direction Dc with the second receiving coil 32. The fourth receiving coil 34 outputs a voltage that is out of phase with the voltages of the first receiving coil 31, the second receiving coil 32, and the third receiving coil 33.

[0367] Furthermore, the third coil inner end 338 is located further outward in the radial direction Dr than the second coil outer end 326 and the fourth coil outer end 346 .

[0368] Furthermore, the first inter-coil angle θ12 is an angle related to (n1+1 / 4)×α, and the second inter-coil angle θ13 is an angle related to (n2+1 / 2)×α.

[0369] Here, the angle formed by the second center line LM2 and the fourth center line LM4 is defined as a fifth inter-coil angle θ24.

[0370] The fifth inter-coil angle θ24 is an angle related to (n3 + ½) × α. For example, n1 = 0, n2 = 0, and n3 = 0. Therefore, the first inter-coil angle θ12 is ¼ × α. The second inter-coil angle θ13 is ½ × α. The fifth inter-coil angle θ24 is ½ × α.

[0371] Furthermore, assume that the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 output voltages having a periodicity that corresponds to the change in the magnetic field caused by the convex portion 252. At this time, the connection states and winding directions of the first receiving coil 31 and the third receiving coil 33 are adjusted so that a current flows through the first receiving coil 31 in the opposite direction to the current flowing through the third receiving coil 33. At this time, the connection states and winding directions of the second receiving coil 32 and the fourth receiving coil 34 are adjusted so that a current flows through the second receiving coil 32 in the opposite direction to the current flowing through the fourth receiving coil 34.

[0372] Therefore, the detector 50 detects the voltage across the first and third receiver coils 31 and 33, which are connected to each other, to obtain the difference in voltage between the first and third receiver coils 31 and 33. Furthermore, the detector 50 detects the voltage across the second and fourth receiver coils 32 and 34, which are connected to each other, to obtain the difference in voltage between the second and fourth receiver coils 32 and 34.

[0373] As described above, the voltage waveform of the first receiving coil 31 after envelope processing is sinusoidal. Furthermore, since the second inter-coil angle θ13 is set to ½×α, the phase difference between the voltage of the first receiving coil 31 and the voltage of the third receiving coil 33 is ½ period. Therefore, the voltage waveform of the difference between the voltages of the first receiving coil 31 and the third receiving coil 33 after envelope processing relative to the rotation angle of the target 25 also becomes sinusoidal.

[0374] Furthermore, as described above, because the first inter-coil angle θ12 is ¼×α, the phase difference between the voltage of the first receiving coil 31 and the voltage of the second receiving coil 32 is ¼ period. Therefore, the voltage waveform of the second receiving coil 32 that has undergone envelope processing is a cosine wave. Furthermore, because the fifth inter-coil angle θ24 is ½×α, the phase difference between the voltages of the second receiving coil 32 and the fourth receiving coil 34 is ½ period. Therefore, the voltage waveform of the difference between the voltages of the second receiving coil 32 and the fourth receiving coil 34 that have undergone envelope processing relative to the rotation angle of the target 25 also has a cosine wave shape.

[0375] Therefore, the detection unit 50 divides the difference in voltage between the first receiving coil 31 and the third receiving coil 33, which have been subjected to envelope processing, by the difference in voltage between the second receiving coil 32 and the fourth receiving coil 34, which have been subjected to envelope processing. The detection unit 50 then calculates the arc tangent of this divided value. Furthermore, the detection unit 50 calculates the rotation angle of the target 25 from the calculated arc tangent value. In this way, the detection unit 50 detects the rotation angle of the target 25.

[0376] Moreover, here, the convex portion outer end 256 is located in the radial direction Dr more inward than the first coil outer end 316 and the third coil outer end 336. Furthermore, the convex portion outer end 256 is located in the radial direction Dr more outward than the second coil outer end 326 and the fourth coil outer end 346.

[0377] Furthermore, the convex portion inner end 258 is located more inward in the radial direction Dr than the second coil inner end 328 and the fourth coil inner end 348 .

[0378] Furthermore, when the target 25 is displaced in the radial direction Dr, the portions where the convex portion 252 directly faces the first receiving coil 31 and the third receiving coil 33 change, causing the eddy current to change, and therefore the voltages of the first receiving coil 31 and the third receiving coil 33 change. When the target 25 is displaced in the radial direction Dr, the portions where the convex portion 252 directly faces the second receiving coil 32 and the fourth receiving coil 34 do not change, causing the eddy current to not change, and therefore the voltages of the second receiving coil 32 and the fourth receiving coil 34 do not change.

[0379] Therefore, the detector 50 calculates the displacement of the target 25 in the radial direction Dr based on the voltages of the first receiving coil 31 and the third receiving coil 33 .

[0380] Specifically, the detection unit 50 calculates the displacement of the target 25 in the radial direction Dr from the sum of the voltages of the first receiving coil 31 and the third receiving coil 33 on which envelope processing has been performed. In this way, the detection unit 50 detects the displacement of the target 25 in the radial direction Dr. Note that, instead of the above sum, the detection unit 50 may calculate the displacement of the target 25 in the radial direction Dr from the difference between the voltages of the first receiving coil 31 and the third receiving coil 33 on which envelope processing has been performed. Furthermore, instead of the above sum, the detection unit 50 may calculate the displacement of the target 25 in the radial direction Dr from only the voltage of the first receiving coil 31 on which envelope processing has been performed. Furthermore, instead of the above sum, the detection unit 50 may calculate the displacement of the target 25 in the radial direction Dr from only the voltage of the third receiving coil 33 on which envelope processing has been performed.

[0381] Furthermore, when the target 25 is displaced in the axial direction Da, the distance from the convex portion 252 to the first receiving coil 31 in the axial direction Da changes. At this time, the distance from the convex portion 252 to the second receiving coil 32 in the axial direction Da also changes. At this time, the distance from the convex portion 252 to the third receiving coil 33 in the axial direction Da also changes. At this time, the distance from the convex portion 252 to the fourth receiving coil 34 in the axial direction Da also changes. For these reasons, when the target 25 is displaced in the axial direction Da, the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 change. Furthermore, as described above, when the target 25 is displaced in the radial direction Dr, the voltages of the first receiving coil 31 and the third receiving coil 33 change.

[0382] Therefore, the detector 50 calculates the displacement of the target 25 in the axial direction Da based on the voltages of the second receiving coil 32 and the fourth receiving coil 34 .

[0383] Specifically, the detection unit 50 calculates the displacement of the target 25 in the axial direction Da from the sum of the voltages of the second receiving coil 32 and the fourth receiving coil 34 that have been subjected to envelope processing. In this way, the detection unit 50 detects the displacement of the target 25 in the axial direction Da. Note that, instead of the above sum, the detection unit 50 may calculate the displacement of the target 25 in the axial direction Da from the difference between the voltages of the second receiving coil 32 and the fourth receiving coil 34 that have been subjected to envelope processing. Furthermore, instead of the above sum, the detection unit 50 may calculate the displacement of the target 25 in the axial direction Da from only the voltage of the second receiving coil 32 that has been subjected to envelope processing. Furthermore, instead of the above sum, the detection unit 50 may calculate the displacement of the target 25 in the axial direction Da from only the voltage of the fourth receiving coil 34 that has been subjected to envelope processing.

[0384] Also, assume that the target 25 is tilted with respect to the radial direction Dr. In this case, the distance from the target 25 to the first and third receiver coils 31 and 33 in the axial direction Da is different from the distance from the target 25 to the second and fourth receiver coils 32 and 34. In this case, assume that the target 25 is displaced in the axial direction Da. At this time, since the distances are different, the changes in the magnetic fields are also different, and therefore the sum of the voltages of the first and third receiver coils 31 and 33 is different from the sum of the voltages of the second and fourth receiver coils 32 and 34. Therefore, the value obtained by subtracting the sum of the voltages of the second and fourth receiver coils 32 and 34 from the sum of the voltages of the first and third receiver coils 31 and 33 corresponds to the tilt angle of the target 25 with respect to the radial direction Dr.

[0385] Therefore, the detector 50 detects the tilt angle of the target 25 with respect to the radial direction Dr based on the voltages of the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, and the fourth receiver coil .

[0386] Specifically, the detection unit 50 calculates a value obtained by subtracting the sum of the voltages of the second receiving coil 32 and the fourth receiving coil 34 from the sum of the voltages of the first receiving coil 31 and the third receiving coil 33. Furthermore, the detection unit 50 calculates the tilt angle of the target 25 with respect to the radial direction Dr from this subtracted value. Since the distances are different, the detection unit 50 may calculate the tilt angle of the target 25 with respect to the radial direction Dr from a value obtained by subtracting the voltage of the second receiving coil 32 from the voltage of the first receiving coil 31. Furthermore, the detection unit 50 may calculate the tilt angle of the target 25 with respect to the radial direction Dr from a value obtained by subtracting the voltage of the fourth receiving coil 34 from the voltage of the first receiving coil 31. Furthermore, the detection unit 50 may calculate the tilt angle of the target 25 with respect to the radial direction Dr from a value obtained by subtracting the voltage of the second receiving coil 32 from the voltage of the third receiving coil 33. The detector 50 may also calculate the tilt angle of the target 25 with respect to the radial direction Dr from a value obtained by subtracting the voltage of the fourth receiver coil 34 from the voltage of the third receiver coil 33 .

[0387] The sensor device 20 of the 30th embodiment is configured as described above. The 30th embodiment also provides the same effects as the 27th embodiment. The 30th embodiment also provides the following effects.

[0388] [17-1] Here, the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 contain offset components. Furthermore, these offset components are relatively large. Therefore, it is difficult to perform AD conversion of the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 according to the rotation angle of the detection target.

[0389] Therefore, the detection unit 50 detects the rotation angle of the object to be detected based on a value related to the voltage difference between the first receiving coil 31 and the third receiving coil 33 and a value related to the voltage difference between the second receiving coil 32 and the fourth receiving coil 34.

[0390] As a result, the offset component included in the voltage of the first receiving coil 31 and the offset component included in the voltage of the third receiving coil 33 cancel out, thereby removing the offset components included in the voltages of the first receiving coil 31 and the third receiving coil 33. Furthermore, the offset component included in the voltage of the second receiving coil 32 cancels out the offset component included in the voltage of the fourth receiving coil 34, thereby removing the offset components included in the voltages of the second receiving coil 32 and the fourth receiving coil 34. This makes it easier to perform AD conversion when detecting the rotation angle of the detection target.

[0391] [17-2] Assume that the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 output periodic voltages that correspond to the changes in the magnetic field caused by the convex portion 252. At this time, a current flows through the first receiving coil 31 in the opposite direction to the current flowing through the third receiving coil 33. Furthermore, at this time, a current flows through the second receiving coil 32 in the opposite direction to the current flowing through the fourth receiving coil 34.

[0392] This allows the detection unit 50 to obtain a value relating to the difference in voltage between the first receiving coil 31 and the third receiving coil 33, without having to obtain the voltages of the first receiving coil 31 and the third receiving coil 33 and calculate the difference between them. Furthermore, the detection unit 50 can obtain a value relating to the difference in voltage between the second receiving coil 32 and the fourth receiving coil 34, without having to obtain the voltages of the second receiving coil 32 and the fourth receiving coil 34 and calculate the difference between them. This prevents an increase in the calculation load on the detection unit 50.

[0393] [17-3] The detection unit 50 detects displacement of the detection target in the radial direction Dr based on the voltages of the first receiving coil 31 and the third receiving coil 33. Furthermore, the detection unit 50 detects displacement of the detection target in the axial direction Da based on the voltages of the second receiving coil 32 and the fourth receiving coil 34.

[0394] This allows the displacements in the radial direction Dr and the axial direction Da to be detected separately, thereby suppressing a decrease in the detection accuracy of the displacements in the radial direction Dr and the axial direction Da.

[0395] [17-4] The detector 50 detects the tilt angle of the target 25 with respect to the radial direction Dr based on the voltages of the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, and the fourth receiver coil .

[0396] This makes it possible to detect the tilt angle of the target 25 relative to the radial direction Dr, and therefore the tilt angle of the detection object that is tilted together with the target 25 can be detected.

[0397] 56 , in the 31st embodiment, the shape of the target 25 is different from that in the 30th embodiment. Also, the positional relationship between the target 25, the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, and the fourth receiver coil 34 is different from that in the 30th embodiment. Furthermore, the detection of the displacement of the target 25 in the radial direction Dr and the axial direction Da by the detector 50 is different from that in the 30th embodiment. Other than these, the 31st embodiment is the same as the 30th embodiment.

[0398] Specifically, the convex portion 252 of the target 25 protrudes from the base portion 250 in the axial direction Da, instead of protruding in the radial direction Dr.

[0399] The convex portion outer end 256 is located radially outward of the first coil outer end 316 and the third coil outer end 336 in the radial direction Dr.

[0400] The protruding portion inner end 258 is located in the radial direction Dr more inward than the first coil inner end 318 and the third coil inner end 338. The protruding portion inner end 258 is also located in the radial direction Dr more outward than the second coil inner end 328 and the fourth coil inner end 348.

[0401] In this case, when the target 25 is displaced in the radial direction Dr, the voltages of the first receiving coil 31 and the third receiving coil 33 do not change, but the voltages of the second receiving coil 32 and the fourth receiving coil 34 change. Furthermore, when the target 25 is displaced in the axial direction Da, the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 change.

[0402] Therefore, the detection unit 50 calculates the displacement of the target 25 in the radial direction Dr from the sum of the voltages of the second receiving coil 32 and the fourth receiving coil 34 that have been subjected to envelope processing. In this way, the detection unit 50 detects the displacement of the target 25 in the radial direction Dr. Note that, instead of the above sum, the detection unit 50 may calculate the displacement of the target 25 in the radial direction Dr from the difference between the voltages of the second receiving coil 32 and the fourth receiving coil 34 that have been subjected to envelope processing. Furthermore, instead of the above sum, the detection unit 50 may calculate the displacement of the target 25 in the radial direction Dr from only the voltage of the second receiving coil 32 that has been subjected to envelope processing. Furthermore, instead of the above sum, the detection unit 50 may calculate the displacement of the target 25 in the radial direction Dr from only the voltage of the fourth receiving coil 34 that has been subjected to envelope processing.

[0403] The detection unit 50 also calculates the displacement of the target 25 in the axial direction Da from the sum of the voltages of the first receiving coil 31 and the third receiving coil 33 that have been subjected to envelope processing. As a result, the detection unit 50 detects the displacement of the target 25 in the axial direction Da. Note that, instead of the above sum, the detection unit 50 may calculate the displacement of the target 25 in the axial direction Da from the difference between the voltages of the first receiving coil 31 and the third receiving coil 33 that have been subjected to envelope processing. Furthermore, instead of the above sum, the detection unit 50 may calculate the displacement of the target 25 in the axial direction Da from only the voltage of the first receiving coil 31 that has been subjected to envelope processing. Furthermore, instead of the above sum, the detection unit 50 may calculate the displacement of the target 25 in the axial direction Da from only the voltage of the third receiving coil 33 that has been subjected to envelope processing.

[0404] The sensor device 20 of the 31st embodiment is configured as described above. The 31st embodiment also provides the same effects as the 30th embodiment. The 31st embodiment also provides the following effects.

[0405]

[18] The detector 50 detects displacement of the detection target in the axial direction Da based on the voltages of the first receiver coil 31 and the third receiver coil 33. Furthermore, the detector 50 detects displacement of the detection target in the radial direction Dr based on the voltages of the second receiver coil 32 and the fourth receiver coil 34.

[0406] This allows the displacements in the radial direction Dr and the axial direction Da to be calculated separately, thereby suppressing a decrease in the detection accuracy of the displacements in the radial direction Dr and the axial direction Da.

[0407] Thirty-Second Embodiment The thirty-second embodiment differs from the thirty-first embodiment in the processing by the detection unit 50. Other than this, the thirty-second embodiment is the same as the thirty-first embodiment.

[0408] For example, assume that the tire 12 is displaced simultaneously in the axial direction Da and the radial direction Dr. At this time, the target 25 is displaced simultaneously in the axial direction Da and the radial direction Dr. The sum of the voltages of the first receiving coil 31 and the third receiving coil 33 includes a displacement component of the target 25 in the axial direction Da in addition to a displacement component of the target 25 in the radial direction Dr.

[0409] Therefore, the detection unit 50 detects the displacement of the target 25 in the radial direction Dr using the sum of the voltages of the second receiving coil 32 and the fourth receiving coil 34 in addition to the sum of the voltages of the first receiving coil 31 and the third receiving coil 33. Furthermore, the detection unit 50 detects the displacement of the target 25 in the axial direction Da using the sum of the voltages of the first receiving coil 31 and the third receiving coil 33 in addition to the sum of the voltages of the second receiving coil 32 and the fourth receiving coil 34.

[0410] Specifically, the detection unit 50 calculates V1+V2+V3+V4 by adding the sum of the voltages of the second receiving coil 32 and the fourth receiving coil 34 to the sum of the voltages of the first receiving coil 31 and the third receiving coil 33. The detection unit 50 also calculates (V1+V3)-(V2+V4) by subtracting the sum of the voltages of the second receiving coil 32 and the fourth receiving coil 34 from the sum of the voltages of the first receiving coil 31 and the third receiving coil 33. V1 is the voltage of the first receiving coil 31. V2 is the voltage of the second receiving coil 32. V3 is the voltage of the third receiving coil 33. V4 is the voltage of the fourth receiving coil 34.

[0411] The detection unit 50 then calculates each displacement using V1+V2+V3+V4, (V1+V3)-(V2+V4), a map, and interpolation processing such as a bilinear method. The map for calculating each displacement is set through experiments, simulations, and the like. For example, as shown in FIG. 57 , the map is set so that when each displacement is fixed, (V1+V3)-(V2+V4) decreases as V1+V2+V3+V4 increases. Furthermore, the displacement in the radial direction Dr and V1+V2+V3+V4 are fixed, and (V1+V3)-(V2+V4) increases as the displacement in the axial direction Da increases. Furthermore, the displacement in the axial direction Da and V1+V2+V3+V4 are fixed, and (V1+V3)-(V2+V4) increases as the displacement in the radial direction Dr increases. In FIG. 57, when the displacement in the radial direction Dr is fixed and there is a displacement in one direction along the axial direction Da, the relationship between V1+V2+V3+V4 and (V1+V3)-(V2+V4) in the map is shown as +ΔDa. When the displacement in the radial direction Dr is fixed and there is no displacement in the axial direction Da, the relationship between V1+V2+V3+V4 and (V1+V3)-(V2+V4) in the map is shown as ΔDa=0. When the displacement in the radial direction Dr is fixed and there is a displacement in the opposite direction to the one direction along the axial direction Da, the relationship between V1+V2+V3+V4 and (V1+V3)-(V2+V4) in the map is shown as -ΔDa. When the displacement in the axial direction Da is fixed and there is a displacement in one direction along the radial direction Dr, the relationship between V1+V2+V3+V4 and (V1+V3)-(V2+V4) in the map is shown as +ΔDa. When the displacement in the axial direction Da is fixed and there is no displacement in the radial direction Dr, the relationship between V1 + V2 + V3 + V4 and (V1 + V3) - (V2 + V4) in the map is shown as ΔDr = 0. When the displacement in the axial direction Da is fixed and there is displacement in the opposite direction to one direction in the radial direction Dr, the relationship between V1 + V2 + V3 + V4 and (V1 + V3) - (V2 + V4) in the map is shown as -ΔDr.

[0412] The sensor device 20 of the 32nd embodiment is configured as described above. The 32nd embodiment also provides the same effects as the 30th embodiment. The 32nd embodiment also provides the following effects.

[0413]

[19] The detection unit 50 detects the displacement of the detection object in the axial direction Da and the radial direction Dr based on the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34.

[0414] This allows the displacements in the radial direction Dr and the axial direction Da to be detected separately with relatively high accuracy, thereby suppressing a decrease in the detection accuracy of the displacements in the radial direction Dr and the axial direction Da.

[0415] 58 , in the 33rd embodiment, the sensor device 20 further includes a fifth receiving coil 35. The shapes of the second receiving coil 32 and the fourth receiving coil 34 are different from those in the 30th embodiment. Furthermore, the processing by the detection unit 50 is different from that in the 30th embodiment. Other than these, the sensor device 20 is the same as the 30th embodiment.

[0416] Specifically, the fifth receiving coil 35 is aligned in the circumferential direction Dc with the second receiving coil 32 and the fourth receiving coil 34. The fifth receiving coil 35 outputs a voltage that is out of phase with the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34.

[0417] Furthermore, the fifth receiving coil 35 has a fifth coil outer end 356 and a fifth coil inner end 358. The fifth coil outer end 356 is the outer end of the fifth receiving coil 35 in the radial direction Dr. The fifth coil inner end 358 is the inner end of the fifth receiving coil 35 in the radial direction Dr.

[0418] Furthermore, the fifth coil outer end 356 is located more inward in the radial direction Dr than the first coil inner end 318 and the third coil inner end 338 .

[0419] Furthermore, the convex portion outer end 256 is located further outward in the radial direction Dr than the fifth coil outer end 356 in the radial direction Dr.

[0420] Furthermore, the convex portion inner end 258 is located more inward in the radial direction Dr than the fifth coil inner end 358 in the radial direction Dr.

[0421] Furthermore, the fourth receiving coil 34 is located between the second receiving coil 32 and the fifth receiving coil 35 in the circumferential direction Dc.

[0422] When viewed from the axial direction Da, a line connecting the rotation axis Or and the end of the first receiving coil 31 opposite to the third receiving coil 33 coincides with a line connecting the rotation axis Or and the end of the second receiving coil 32 opposite to the fourth receiving coil 34. When viewed from the axial direction Da, a line connecting the rotation axis Or and the end of the third receiving coil 33 opposite to the first receiving coil 31 coincides with a line connecting the rotation axis Or and the end of the fifth receiving coil 35 opposite to the fourth receiving coil 34.

[0423] When viewed from the axial direction Da, the angle formed by a line connecting the end of the first receiver coil 31 opposite the third receiver coil 33 to the rotation axis Or and a line connecting the end of the third receiver coil 33 opposite the first receiver coil 31 to the rotation axis Or is α. When viewed from the axial direction Da, the angle formed by a line connecting the end of the second receiver coil 32 opposite the fourth receiver coil 34 to the rotation axis Or and a line connecting the end of the second receiver coil 32 on the fourth receiver coil 34 side to the rotation axis Or is α / 4. When viewed from the axial direction Da, the angle formed by a line connecting the end of the fourth receiver coil 34 on the second receiver coil 32 side to the rotation axis Or and a line connecting the end of the fourth receiver coil 34 on the fifth receiver coil 35 side to the rotation axis Or is α / 2. Furthermore, when viewed from the axial direction Da, the angle formed by the line connecting the end of the fifth receiving coil 35 opposite the fourth receiving coil 34 to the rotation axis Or and the line connecting the end of the fifth receiving coil 35 on the fourth receiving coil 34 side to the rotation axis Or is α / 4.

[0424] Assume also that the second, fourth, and fifth receiver coils 32, 34, and 35 output voltages with periodicity corresponding to the changes in the magnetic field caused by the convex portion 252. At this time, the connection states and winding directions of the second and fifth receiver coils 32, 35 are adjusted so that currents flow in the same direction through the second and fifth receiver coils 32, 35. Furthermore, the connection states and winding directions of the second, fourth, and fifth receiver coils 32, 34, and 35 are adjusted so that currents flow in the fourth receiver coil 34 in the opposite direction to the currents flowing through the second and fifth receiver coils 32, 35. At this time, the sum of the voltages of the second and fifth receiver coils 32 and 35 corresponds to the voltage of the second receiver coil 32 in the thirtieth embodiment.

[0425] Therefore, the detection unit 50 detects the rotation angle and displacement of the target 25 based on the voltages of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, the fourth receiving coil 34, and the fifth receiving coil 35. Specifically, the voltage of the second receiving coil 32 is interpreted as the sum of the voltages of the second receiving coil 32 and the fifth receiving coil 35, and the rotation angle and displacement of the target 25 are detected in the same way as in the 30th embodiment.

[0426] The sensor device 20 of the 33rd embodiment is configured as described above. The 33rd embodiment also provides the same effects as the 30th embodiment. The 33rd embodiment also provides the following effects.

[0427]

[20] Here, suppose that the end of the first receiving coil 31 is not aligned with the end of the second receiving coil 32, and the end of the third receiving coil 33 is not aligned with the end of the fifth receiving coil 35. In this case, the size of the sensor device 20 in the circumferential direction Dc increases.

[0428] In contrast to this, in the thirty-third embodiment, an end of the first receiving coil 31 is aligned with an end of the second receiving coil 32. Also, an end of the third receiving coil 33 is aligned with an end of the fifth receiving coil 35. This prevents the sensor device 20 from becoming larger in size in the circumferential direction Dc.

[0429] 59 , in the 34th embodiment, the shape of the target 25 is different from that in the 33rd embodiment. In addition, the positional relationship between the target 25, the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, the fourth receiver coil 34, and the fifth receiver coil 35 is different from that in the 33rd embodiment.

[0430] Specifically, the convex portion 252 of the target 25 protrudes from the base portion 250 in the axial direction Da, instead of protruding in the radial direction Dr.

[0431] The convex portion outer end 256 is located radially outward of the first coil outer end 316 and the third coil outer end 336 in the radial direction Dr.

[0432] The convex portion inner end 258 is located in the radial direction Dr more inward than the first coil inner end 318 and the third coil inner end 338. Furthermore, the convex portion inner end 258 is located in the radial direction Dr more outward than the second coil inner end 328, the fourth coil inner end 348, and the fifth coil inner end 358. In this case, the detection unit 50 detects the displacement of the target 25 in the radial direction Dr and the axial direction Da by performing the same processing as in the thirty-first embodiment.

[0433] The sensor device 20 of the thirty-fourth embodiment is configured as described above. The thirty-fourth embodiment also provides the same effects as the thirty-third embodiment.

[0434] Thirty-fifth Embodiment As shown in Fig. 60, the thirty-fifth embodiment differs from the thirty-first embodiment in the shape of the target 25. Other than this, the thirty-fifth embodiment is similar to the thirty-first embodiment.

[0435] Specifically, instead of protruding outward in the radial direction Dr, the protruding portions 252 of the target 25 protrude inward in the radial direction Dr from the base portion 250. In this case, the protruding portion outer ends 256 correspond to the boundary portions of the protruding portions 252 with the base portion 250. Furthermore, the protruding portion inner ends 258 correspond to the tips of the protruding portions 252 that face the rotation axis Or. Furthermore, the recessed portions 254 are defined as spaces formed between adjacent protruding portions 252.

[0436] The sensor device 20 of the thirty-fifth embodiment is configured as described above. The thirty-fifth embodiment also provides the same effects as the thirty-first embodiment.

[0437] 61 to 64, the thirty-sixth embodiment differs from the second embodiment in the shapes of the target 25, the first receiving coil 31, and the second receiving coil 32. The sensor device 20 further includes a third receiving coil 33. Furthermore, the detection of the displacement of the target 25 in the radial direction Dr and the axial direction Da by the detection unit 50 differs from the second embodiment. Other than these, the thirty-sixth embodiment is similar to the second embodiment.

[0438] Specifically, instead of protruding in the axial direction Da, the protruding portion 252 protrudes outward from the base portion 250 in the radial direction Dr. In this case, the protruding portion inner end 258 corresponds to the boundary portion of the protruding portion 252 with the base portion 250. Furthermore, the recessed portion 254 is defined as a space formed between adjacent protruding portions 252.

[0439] Instead of being formed in a spiral shape, the first receiving coil 31 and the second receiving coil 32 are formed in a sine wave shape and a cosine wave shape extending on a plane perpendicular to the axial direction Da. Here, the first receiving coil 31 is formed in a sine wave shape as shown in Fig. 62. The second receiving coil 32 is formed in a cosine wave shape as shown in Fig. 63.

[0440] Also, returning to FIG. 61, the first coil outer end 316 is located more inward in the radial direction Dr than the convex portion outer end 256 in the radial direction Dr.

[0441] Furthermore, the first coil inner end 318 is located further outward in the radial direction Dr than the convex portion inner end 258 .

[0442] Furthermore, the second coil outer end 326 is located more inward in the radial direction Dr than the convex portion outer end 256 in the radial direction Dr.

[0443] Furthermore, the second coil inner end 328 is located further outward in the radial direction Dr than the convex portion inner end 258 .

[0444] The third receiving coil 33 is formed in a spiral shape extending on a plane perpendicular to the axial direction Da. Note that the third receiving coil 33 is not limited to being formed in a spiral shape, and may be formed in a sine wave or cosine wave shape extending on a plane perpendicular to the axial direction Da.

[0445] Furthermore, the third receiving coil 33 is disposed at a position different from the first receiving coil 31 and the second receiving coil 32. Here, the third receiving coil 33 is disposed side by side with the first receiving coil 31 and the second receiving coil 32 in the circumferential direction Dc. Furthermore, the third receiving coil 33 outputs a voltage according to the displacement of the convex portion 252.

[0446] The third receiving coil 33 is formed so that α≦θc3 holds. Alternatively, the third receiving coil 33 may be formed so that θc3=m×α holds, where m is a natural number.

[0447] The third receiving coil 33 has a third coil outer end 336 and a third coil inner end 338. The third coil outer end 336 is the outer end of the third receiving coil 33 in the radial direction Dr. The third coil inner end 338 is the inner end of the third receiving coil 33 in the radial direction Dr.

[0448] Furthermore, as shown in FIGS. 61 and 64, the third coil outer end 336 is located further outward in the radial direction Dr than the convex portion outer end 256 in the radial direction Dr.

[0449] Furthermore, the third coil inner end 338 is located more inward in the radial direction Dr than the convex portion inner end 258 in the radial direction Dr.

[0450] Here, as described above, the third receiving coil 33 outputs a voltage according to the displacement of the convex portion 252, and therefore the detection unit 50 detects the displacement of the convex portion 252 based on the voltage of the third receiving coil 33. In this way, the detection unit 50 detects the displacement of the target 25.

[0451] Furthermore, when the target 25 is displaced in the radial direction Dr, the eddy current does not change because the portion where the convex portion 252 directly faces the first receiving coil 31 and the second receiving coil 32 does not change, and therefore there is no change in the voltage of the first receiving coil 31 and the second receiving coil 32. Furthermore, when the target 25 is displaced in the radial direction Dr, the portion where the convex portion 252 directly faces the third receiving coil 33 changes, and therefore the eddy current changes, and therefore the voltage of the third receiving coil 33 changes.

[0452] Therefore, the detection unit 50 calculates the displacement of the target 25 in the radial direction Dr from the voltage of the third receiving coil 33 that has undergone the envelope processing. In this way, the detection unit 50 detects the displacement of the target 25 in the radial direction Dr.

[0453] Furthermore, when the target 25 is displaced in the axial direction Da, the distance from the convex portion 252 to the first receiving coil 31 in the axial direction Da changes. Furthermore, at this time, the distance from the convex portion 252 to the second receiving coil 32 in the axial direction Da changes. Furthermore, at this time, the distance from the convex portion 252 to the third receiving coil 33 in the axial direction Da changes. Therefore, when the target 25 is displaced in the axial direction Da, the voltages of the first receiving coil 31, the second receiving coil 32, and the third receiving coil 33 change. Furthermore, as described above, when the target 25 is displaced in the radial direction Dr, the voltages of the first receiving coil 31 and the second receiving coil 32 do not change, but the voltage of the third receiving coil 33 changes.

[0454] Therefore, the detection unit 50 calculates the displacement of the target 25 in the axial direction Da based on the voltages of the first receiving coil 31 and the second receiving coil 32 that have been subjected to the envelope processing. In this way, the detection unit 50 detects the displacement of the target 25 in the axial direction Da.

[0455] Specifically, the detection unit 50 calculates the displacement of the target 25 in the axial direction Da from the sum of the voltages of the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing. Note that the detection unit 50 may also calculate the displacement of the target 25 in the axial direction Da from the difference between the voltages of the first receiving coil 31 and the second receiving coil 32 that have been subjected to envelope processing. The detection unit 50 may also calculate the displacement of the target 25 in the axial direction Da from only the voltage of the first receiving coil 31 that has been subjected to envelope processing. Furthermore, the detection unit 50 may also calculate the displacement of the target 25 in the axial direction Da from only the voltage of the second receiving coil 32 that has been subjected to envelope processing.

[0456] In addition, assume that the target 25 is displaced simultaneously in the radial direction Dr and the axial direction Da. At this time, the voltage of the third receiving coil 33 includes a displacement component of the target 25 in the axial direction Da in addition to a displacement component of the target 25 in the radial direction Dr.

[0457] Therefore, the detection unit 50 may calculate the displacement of the target 25 in the radial direction Dr based on the voltages of the first receiving coil 31 , the second receiving coil 32 , and the third receiving coil 33 .

[0458] Specifically, the detection unit 50 calculates the displacement component of the target 25 in the axial direction Da contained in the voltage of the third reception coil 33 from the voltages of the first reception coil 31 and the second reception coil 32. Furthermore, the detection unit 50 subtracts a voltage corresponding to the displacement component of the target 25 in the axial direction Da from the voltage of the third reception coil 33. Furthermore, the detection unit 50 calculates the displacement of the target 25 in the radial direction Dr from the value obtained by this subtraction.

[0459] The sensor device 20 of the 36th embodiment is configured as described above. The 36th embodiment also provides the same effects as the second embodiment. The 36th embodiment also provides the following effects.

[0460] [21-1] Here, the specification of JP-A-2019-520577, which corresponds to DE-A-102016211832, discloses a rotation angle sensor that detects a rotation angle using a compensation receiving coil.

[0461] In a sensor that detects a rotation angle, it is required to detect displacement in addition to detecting the rotation angle. However, when the compensation receiver coil described in this patent document is used to detect displacement in addition to the rotation angle, it is difficult to detect the displacement because the voltage change of the compensation receiver coil corresponding to the displacement is small.

[0462] In contrast to this, in the thirty-sixth embodiment, the detection unit 50 detects the rotation angle of the detection object based on the voltages of the first receiving coil 31 and the second receiving coil 32. Furthermore, the detection unit 50 detects the displacement of the detection object based on the voltage of the third receiving coil 33.

[0463] As a result, the rotation angle and displacement of the detection object are detected by the dedicated coils, making it easier to detect the rotation angle of the detection object and the displacement of the detection object.

[0464] [21-2] The third receiving coil 33 and the target 25 are formed so that α≦θc3 holds.

[0465] As a result, when the convex portion 252 rotates, the area of ​​the portion of the convex portion 252 that directly faces the third receiving coil 33 is more likely to change. This makes it easier for the voltage of the third receiving coil 33 to change. This makes it easier to detect the displacement of the detection target. This prevents a decrease in the detection accuracy of the displacement of the detection target.

[0466] [21-3] The third receiving coil 33 and the target 25 are preferably formed so that θc3=m×α holds.

[0467] As a result, when the target 25 rotates, the area ratio of the convex portion 252 and the concave portion 254 facing the third receiving coil 33 in the axial direction Da is 1:1 at any rotation position. This suppresses fluctuations in the sensitivity of the third receiving coil 33 to the displacement of the detection target. This makes it easier to detect the displacement of the detection target. This suppresses a decrease in the detection accuracy of the displacement of the detection target.

[0468] [21-4] The detection unit 50 detects the displacement of the target 25 in the axial direction Da based on the voltages of the first receiving coil 31 and the second receiving coil 32. The detection unit 50 also detects the displacement of the target 25 in the radial direction Dr based on the voltages of the first receiving coil 31, the second receiving coil 32, and the third receiving coil 33.

[0469] This allows the displacements in the radial direction Dr and the axial direction Da to be detected separately, thereby suppressing a decrease in the detection accuracy of the displacements in the radial direction Dr and the axial direction Da.

[0470] Thirty-seventh embodiment As shown in Fig. 65, the thirty-seventh embodiment differs from the thirty-sixth embodiment in the shapes of the first receiver coil 31 and the second receiver coil 32. Other than this, the thirty-seventh embodiment is similar to the thirty-sixth embodiment.

[0471] Specifically, instead of being formed in a sine wave and a cosine wave, the first receiving coil 31 and the second receiving coil 32 are formed in a spiral shape extending on a plane perpendicular to the rotation axis Or. Furthermore, the first receiving coil 31 and the second receiving coil 32 are aligned in the circumferential direction Dc. As a result, the first receiving coil 31 and the second receiving coil 32 output voltages of different phases from each other.

[0472] The sensor device 20 of the 37th embodiment is configured as described above. The 37th embodiment also provides the same effects as the 36th embodiment.

[0473] 66 and 67 , in the 38th embodiment, the sensor device 20 further includes a fourth receiving coil 34. Also, the detection of the displacement of the target 25 in the radial direction Dr and the axial direction Da by the detection unit 50 differs from that of the 36th embodiment. Other than this, the sensor device 20 is the same as the 36th embodiment.

[0474] Specifically, the fourth receiving coil 34 is formed in a spiral shape extending on a plane perpendicular to the axial direction Da. Note that the fourth receiving coil 34 is not limited to being formed in a spiral shape, and may be formed in a sine wave shape and a cosine wave shape extending on a plane perpendicular to the axial direction Da.

[0475] Furthermore, the fourth receiving coil 34 is disposed at a position different from the first receiving coil 31, the second receiving coil 32, and the third receiving coil 33. Here, the fourth receiving coil 34 is disposed alongside the first receiving coil 31 and the second receiving coil 32 in the circumferential direction Dc. Furthermore, the fourth receiving coil 34 outputs a voltage according to the displacement of the convex portion 252.

[0476] The fourth receiving coil 34 is formed so that α≦θc4 holds. Furthermore, the third receiving coil 33 and the fourth receiving coil 34 are formed so that θc3=θc4 holds. The fourth receiving coil 34 may be formed so that θc4=m×α holds.

[0477] Furthermore, the fourth receive coil 34 has a fourth coil outer end 346 and a fourth coil inner end 348. The fourth coil outer end 346 is the outer end of the fourth receive coil 34 in the radial direction Dr. The fourth coil inner end 348 is the inner end of the fourth receive coil 34 in the radial direction Dr.

[0478] Furthermore, the fourth coil outer end 346 is located more inward in the radial direction Dr than the third coil inner end 338. In other words, the third coil inner end 338 is located more outward in the radial direction Dr than the fourth coil outer end 346. Therefore, the third receiver coil 33 and the fourth receiver coil 34 are aligned in the radial direction Dr.

[0479] Furthermore, the fourth coil outer end 346 is located between the convex portion outer end 256 and the convex portion inner end 258 in the radial direction Dr. Therefore, the fourth coil outer end 346 is located more inward in the radial direction Dr than the convex portion outer end 256 in the radial direction Dr. Furthermore, the fourth coil outer end 346 is located more outward in the radial direction Dr than the convex portion inner end 258 in the radial direction Dr. Therefore, the third coil inner end 338 is located more outward in the radial direction Dr than the convex portion inner end 258 in the radial direction Dr. Therefore, the third coil inner end 338 is located between the convex portion outer end 256 and the convex portion inner end 258 in the radial direction Dr.

[0480] Furthermore, the fourth coil inner end 348 is located more inward in the radial direction Dr than the convex portion inner end 258 in the radial direction Dr.

[0481] Here, as described above, the third receiving coil 33 and the fourth receiving coil 34 output voltages according to the displacement of the convex portion 252, and therefore the detection unit 50 detects the displacement of the convex portion 252 based on the voltages of the third receiving coil 33 and the fourth receiving coil 34. In this way, the detection unit 50 detects the displacement of the target 25.

[0482] Furthermore, when the target 25 is displaced in the radial direction Dr, the portions directly facing the convex portion 252 and the third and fourth receiving coils 33 and 34 change, causing changes in the eddy currents, and therefore the voltages of the third and fourth receiving coils 33 and 34 change. Here, as shown in FIG. 68 , as the target 25 is displaced outward in the radial direction Dr, the voltage of the third receiving coil 33 decreases. Furthermore, as the target 25 is displaced outward in the radial direction Dr, the voltage of the fourth receiving coil 34 increases. Note that the winding directions of the third and fourth receiving coils 33 and 34 may be adjusted so that the voltage of the third receiving coil 33 increases and the voltage of the fourth receiving coil 34 decreases as the target 25 is displaced outward in the radial direction Dr. Also, in FIG. 68 , the displacement of the target 25 in the radial direction Dr is indicated as ΔDr. The displacement of the target 25 toward the outside in the radial direction Dr is indicated as +ΔDr. The displacement of the target 25 in the radial direction Dr is shown as -ΔDr. The voltage of the third receiving coil 33 is shown as V3. The voltage of the fourth receiving coil 34 is shown as V4.

[0483] Furthermore, when the target 25 is displaced in the axial direction Da, the distance from the convex portion 252 to the third receive coil 33 in the axial direction Da changes. At this time, the distance from the convex portion 252 to the fourth receive coil 34 in the axial direction Da also changes. Therefore, when the target 25 is displaced in the axial direction Da, the voltages of the third receive coil 33 and the fourth receive coil 34 change. Here, as shown in FIG. 69 , the voltage of the third receive coil 33 increases as the target 25 is displaced in the axial direction Da in a direction away from the third receive coil 33 and the fourth receive coil 34. Furthermore, the voltage of the fourth receive coil 34 increases as the target 25 is displaced in the axial direction Da in a direction away from the third receive coil 33 and the fourth receive coil 34. Note that the voltages of the third receive coil 33 and the fourth receive coil 34 may decrease as the target 25 is displaced in the axial direction Da in a direction away from the third receive coil 33 and the fourth receive coil 34. In this way, the winding directions of the third receiving coil 33 and the fourth receiving coil 34 may be adjusted. Also, in Fig. 69, the displacement of the target 25 in the axial direction Da is shown as ΔDa. The displacement of the target 25 in the axial direction Da in the direction away from the third receiving coil 33 and the fourth receiving coil 34 is shown as +ΔDa. The displacement of the target 25 in the axial direction Da in the direction approaching the third receiving coil 33 and the fourth receiving coil 34 is shown as -ΔDa. The voltage of the third receiving coil 33 is shown as V3. The voltage of the fourth receiving coil 34 is shown as V4.

[0484] Assume that the target 25 is displaced simultaneously in the radial direction Dr and the axial direction Da. At this time, the voltages of the third receiving coil 33 and the fourth receiving coil 34 include a displacement component of the target 25 in the axial direction Da in addition to a displacement component of the target 25 in the radial direction Dr.

[0485] Furthermore, as described above, when the target 25 is displaced in the radial direction Dr, the voltage change in the third receiving coil 33 is opposite to the voltage change in the fourth receiving coil 34. When the target 25 is displaced in the axial direction Da, the voltage change in the third receiving coil 33 is the same as the voltage change in the fourth receiving coil 34.

[0486] Therefore, the difference in voltage between the third receiving coil 33 and the fourth receiving coil 34 corresponds to the displacement component of the target 25 in the radial direction Dr, since the displacement components of the target 25 in the axial direction Da are canceled out. Furthermore, the sum of the voltages between the third receiving coil 33 and the fourth receiving coil 34 corresponds to the displacement component of the target 25 in the axial direction Da, since the displacement components of the target 25 in the radial direction Dr are canceled out.

[0487] Therefore, the detection unit 50 calculates the displacement of the target 25 in the radial direction Dr from the difference in voltage between the third receiving coil 33 and the fourth receiving coil 34. The detection unit 50 also calculates the displacement of the target 25 in the axial direction Da from the sum of the voltages of the third receiving coil 33 and the fourth receiving coil 34. In this way, the detection unit 50 detects the displacement of the target 25 in the radial direction Dr and the displacement of the target 25 in the axial direction Da.

[0488] The sensor device 20 of the 38th embodiment is configured as described above. The 38th embodiment also provides the same effects as the 36th embodiment. The 38th embodiment also provides the following effects.

[0489]

[22] The detection unit 50 detects the displacement of the detection object in the radial direction Dr and the displacement of the detection object in the axial direction Da based on the voltages of the third receiving coil 33 and the fourth receiving coil 34. Specifically, the detection unit 50 detects the displacement of the detection object in the radial direction Dr based on a value related to the difference between the voltages of the third receiving coil 33 and the fourth receiving coil 34. Furthermore, the detection unit 50 detects the displacement of the detection object in the axial direction Da based on a value related to the sum of the voltages of the third receiving coil 33 and the fourth receiving coil 34.

[0490] This allows the displacements in the radial direction Dr and the axial direction Da to be detected separately, thereby suppressing a decrease in the detection accuracy of the displacements in the radial direction Dr and the axial direction Da.

[0491] 70 , the 39th embodiment differs from the 38th embodiment in the positional relationship between the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, and the fourth receiver coil 34. Other than this, the 39th embodiment is the same as the 38th embodiment.

[0492] Specifically, instead of being aligned with the first receiving coil 31 and the second receiving coil 32 in the circumferential direction Dc, the third receiving coil 33 and the fourth receiving coil 34 are aligned with the first receiving coil 31 and the second receiving coil 32 in the axial direction Da.

[0493] The sensor device 20 of the thirty-ninth embodiment is configured as described above. The thirty-ninth embodiment also provides the same effects as the thirty-eighth embodiment.

[0494] 71 , the shape of the target 25 in the fortieth embodiment is different from that in the thirty-eighth embodiment. Also, the positional relationship between the target 25, the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, and the fourth receiver coil 34 is different from that in the thirty-eighth embodiment. Other than these, the fortieth embodiment is the same as the thirty-eighth embodiment.

[0495] Specifically, the target 25 has a first convex portion 261 , a first concave portion 271 , a second convex portion 262 , and a second concave portion 272 instead of the convex portion 252 and the concave portion 254 .

[0496] The first protrusions 261 protrude in the axial direction Da from the base portion 250. Furthermore, the first protrusions 261 are arranged at intervals in the circumferential direction Dc.

[0497] The first recessed portions 271 are formed between adjacent first protruding portions 261, and thus a plurality of first recessed portions 271 are arranged at intervals in the circumferential direction Dc.

[0498] The second protrusions 262 protrude in the axial direction Da from the base portion 250. The second protrusions 262 are arranged at intervals in the circumferential direction Dc.

[0499] The second recessed portions 272 are formed between adjacent second protruding portions 262, and thus are arranged at intervals in the circumferential direction Dc.

[0500] Furthermore, the first convex portion 261 and the first concave portion 271 are located further outward in the radial direction Dr than the second convex portion 262 and the second concave portion 272. Therefore, the first convex portion 261 and the first concave portion 271 are aligned with the second convex portion 262 and the second concave portion 272 in the radial direction Dr.

[0501] The first protrusion 261 has a first protrusion outer end 281 and a first protrusion inner end 291. The first protrusion outer end 281 is the outer end of the first protrusion 261 in the radial direction Dr. The first protrusion inner end 291 is the inner end of the first protrusion 261 in the radial direction Dr.

[0502] Furthermore, the first coil outer end 316 is located more inward in the radial direction Dr than the first convex portion outer end 281 in the radial direction Dr.

[0503] Furthermore, the first coil inner end 318 is located further outward in the radial direction Dr than the first convex portion inner end 291 .

[0504] Furthermore, the second coil outer end 326 is located more inward in the radial direction Dr than the first convex portion outer end 281 in the radial direction Dr.

[0505] Furthermore, the second coil inner end 328 is located further outward in the radial direction Dr than the first convex portion inner end 291 .

[0506] Furthermore, the first coil inner end 318 and the second coil inner end 328 are located further outward in the radial direction Dr than the third coil outer end 336. Therefore, the first receiver coil 31 and the second receiver coil 32 are aligned with the third receiver coil 33 and the fourth receiver coil 34 in the radial direction Dr.

[0507] The second protrusion 262 has a second protrusion outer end 282 and a second protrusion inner end 292. The second protrusion outer end 282 is the outer end of the second protrusion 262 in the radial direction Dr. The second protrusion inner end 292 is the inner end of the second protrusion 262 in the radial direction Dr.

[0508] Furthermore, the third coil outer end 336 is located further outward in the radial direction Dr than the second convex portion outer end 282. The third coil outer end 336 is also located further inward in the radial direction Dr than the first convex portion inner end 291.

[0509] Furthermore, the third coil inner end 338 is located further outward in the radial direction Dr than the fourth coil outer end 346 in the radial direction Dr.

[0510] Furthermore, the fourth coil inner end 348 is located more inward in the radial direction Dr than the second convex portion inner end 292 in the radial direction Dr.

[0511] The sensor device 20 of the fortieth embodiment is configured as described above. The fortieth embodiment also provides the same effects as the thirty-eighth embodiment.

[0512] Forty-First Embodiment In the forty-first embodiment, as shown in FIG. 72, the positional relationship between the target 25, the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34 differs from that in the fortieth embodiment.

[0513] Specifically, the first coil outer end 316 is located in place of the first convex portion outer end 281 and is located more inward in the radial direction Dr than the second convex portion outer end 282 in the radial direction Dr.

[0514] The first coil inner end 318 is positioned outside the first convex portion inner end 291 in the radial direction Dr relative to the second convex portion inner end 292 .

[0515] The second coil outer end 326 is located in place of the first convex portion outer end 281 and is located more inward in the radial direction Dr than the second convex portion outer end 282 in the radial direction Dr.

[0516] The second coil inner end 328 is positioned outside the first convex portion inner end 291 in the radial direction Dr relative to the second convex portion inner end 292 .

[0517] The third coil outer end 336 is positioned outside the first convex outer end 281 in the radial direction Dr, instead of the second convex outer end 282 .

[0518] The fourth coil inner end 348 is located in the radial direction Dr more inward than the first convex portion inner end 291, in place of the second convex portion inner end 292. The fourth coil inner end 348 is also located in the radial direction Dr more outward than the second convex portion outer end 282.

[0519] The sensor device 20 of the 41st embodiment is configured as described above. The 41st embodiment also provides the same effects as the 40th embodiment.

[0520] 73, the 42nd embodiment differs from the 40th embodiment in the shape of the target 25. Other than this, the 42nd embodiment is similar to the 40th embodiment.

[0521] Specifically, the second protrusion 262 is formed as a single annular portion, so that the target 25 does not have a second recess 272 .

[0522] The sensor device 20 of the 42nd embodiment is configured as described above. The 42nd embodiment also provides the same effects as the 40th embodiment.

[0523] 74 , the 43rd embodiment differs from the 38th embodiment in the positional relationship between the target 25, the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, and the fourth receiver coil 34. Other than this, the 43rd embodiment is the same as the 38th embodiment.

[0524] Specifically, the first and second receiving coils 31 and 32 are located between the third and fourth receiving coils 33 and 34 in the radial direction Dr. Therefore, the first coil outer end 316, the first coil inner end 318, the second coil outer end 326 and the second coil inner end 328 are located between the third coil inner end 338 and the fourth coil outer end 346.

[0525] The sensor device 20 of the 43rd embodiment is configured as described above. The 43rd embodiment also provides the same effects as the 38th embodiment.

[0526] 75 and 76, in the forty-fourth embodiment, the target 25 further has a rib portion 295. Other than this, the forty-fourth embodiment is the same as the thirty-eighth embodiment.

[0527] The rib portions 295 are disposed between adjacent protrusions 252. Therefore, the rib portions 295 are disposed in the spaces of the recesses 254. The rib portions 295 also extend in the circumferential direction Dc and are connected to adjacent protrusions 252.

[0528] Furthermore, the rib portion 295 has a rib outer end 297 and a rib inner end 299. The rib outer end 297 is the outer end of the rib portion 295 in the radial direction Dr. The rib inner end 299 is the inner end of the rib portion 295 in the radial direction Dr.

[0529] Furthermore, the rib outer end 297 is located in the radial direction Dr between the third coil outer end 336 and the third coil inner end 338. Therefore, the rib outer end 297 is located more inward in the radial direction Dr than the third coil outer end 336, and more outward in the radial direction Dr than the third coil inner end 338.

[0530] Furthermore, the rib inner end 299 is located in the radial direction Dr between the fourth coil outer end 346 and the fourth coil inner end 348. Therefore, the rib inner end 299 is located more inward in the radial direction Dr than the fourth coil outer end 346, and more outward in the radial direction Dr than the fourth coil inner end 348.

[0531] The sensor device 20 of the 44th embodiment is configured as described above. The 44th embodiment also provides the same effects as the 38th embodiment. The 44th embodiment also provides the following effects.

[0532]

[23] The target 25 further has a rib portion 295. Like the protrusion 252, the rib portion 295 changes the voltages of the third receiving coil 33 and the fourth receiving coil 34 when the target 25 is displaced in the radial direction Dr or the axial direction Da due to the above-described positional relationship.

[0533] Therefore, changes in the voltage of the third receiving coil 33 and the fourth receiving coil 34 are more likely to occur than in the case where the rib portion 295 is not provided. In other words, the sensitivity of the third receiving coil 33 and the fourth receiving coil 34 is improved. This suppresses a decrease in the detection accuracy of the displacement of the detection target in the radial direction Dr and the axial direction Da.

[0534] 77, the 45th embodiment differs from the 44th embodiment in the shape of the rib portion 295. Other than this, the 45th embodiment is similar to the 44th embodiment.

[0535] Specifically, the rib portions 295 are not connected to adjacent protrusions 252 , and spaces are formed between the rib portions 295 and the protrusions 252 .

[0536] The sensor device 20 of the 45th embodiment is configured as described above. The 45th embodiment also provides the same effects as the 44th embodiment.

[0537] (Forty-sixth embodiment) In the forty-sixth embodiment, as shown in Fig. 78, the shapes of the third receiving coil 33 and the fourth receiving coil 34 are different from those of the thirty-eighth embodiment. Other than this, the forty-sixth embodiment is the same as the thirty-eighth embodiment.

[0538] For example, in this example, the area of ​​the third receiving coil 33 is larger than the area of ​​the fourth receiving coil 34. Therefore, as shown in FIG. 79, the voltage of the third receiving coil 33 when the target 25 rotates is larger than the voltage of the fourth receiving coil 34 when the target 25 rotates. Therefore, the voltage difference between the third receiving coil 33 and the fourth receiving coil 34 is relatively large. Therefore, to avoid saturation of AD conversion, it is necessary to reduce the gain when amplifying the voltage difference between the third receiving coil 33 and the fourth receiving coil 34 using an amplifier such as an operational amplifier. This reduces the sensitivity for detecting displacement of the detection target. Furthermore, the smaller gain margin reduces the stability of the detection unit 50. In FIG. 79, the voltage of the third receiving coil 33 is indicated as V3. The voltage of the fourth receiving coil 34 is indicated as V4.

[0539] For this reason, in the 46th embodiment, the number of turns of the third receiving coil 33 is smaller than the number of turns of the fourth receiving coil 34. As a result, as shown in Fig. 80, the voltage of the fourth receiving coil 34 becomes relatively large. Therefore, the difference in voltage between the third receiving coil 33 and the fourth receiving coil 34 becomes small. In Fig. 80, the voltage of the third receiving coil 33 is shown as V3. The voltage of the fourth receiving coil 34 is shown as V4.

[0540] The sensor device 20 of the 46th embodiment is configured as described above. The 46th embodiment also provides the same effects as the 38th embodiment. The 46th embodiment also provides the following effects.

[0541]

[24] The number of turns of the third receiving coil 33 is smaller than the number of turns of the fourth receiving coil 34.

[0542] This makes the voltage difference between the third receiving coil 33 and the fourth receiving coil 34 relatively small. Therefore, the gain when amplifying the voltage difference between the third receiving coil 33 and the fourth receiving coil 34 using an amplifier such as an operational amplifier can be relatively large. At this time, the sensitivity for detecting the displacement of the detection target can be increased. Furthermore, since the gain margin is large, a decrease in the stability of the detection unit 50 is suppressed.

[0543] 81, the 47th embodiment differs from the 46th embodiment in the shapes of the third receiving coil 33 and the fourth receiving coil 34. Other than this, the 47th embodiment is the same as the 46th embodiment.

[0544] Specifically, the number of turns of the third receiving coil 33 is the same as the number of turns of the fourth receiving coil 34. Furthermore, the length of the third receiving coil 33 in the radial direction Dr is shorter than the length of the fourth receiving coil 34 in the radial direction Dr.

[0545] The sensor device 20 of the 47th embodiment is configured as described above. The 47th embodiment also provides the same effects as the 46th embodiment.

[0546] 82 , the 48th embodiment differs from the 38th embodiment in the configurations of the third receiving coil 33 and the fourth receiving coil 34. The processing of the detection unit 50 also differs from the 38th embodiment. Other than this, the 48th embodiment is the same as the 38th embodiment.

[0547] Specifically, the third receiving coil 33 has a third linear portion 333. The third linear portion 333 extends on a plane perpendicular to the rotation axis Or. Furthermore, the third linear portions 333 are arranged in a row at intervals in the axial direction Da.

[0548] The fourth receiving coil 34 has a fourth linear portion 344. The fourth linear portion 344 extends on a plane perpendicular to the rotation axis Or. The fourth linear portions 344 are arranged at intervals in the axial direction Da.

[0549] Here, when the third linear portion 333 and the fourth linear portion 344 are arranged at intervals in the axial direction Da, the inductance and capacitance of the circuit including the third receiving coil 33, the fourth receiving coil 34, and the detection unit 50 increase. This reduces the resonant frequency of the circuit including the third receiving coil 33, the fourth receiving coil 34, and the detection unit 50. If this resonant frequency is low, it is necessary to lower the frequency of the voltage applied to the excitation coil 40 to avoid resonance. If the frequency of the voltage applied to the excitation coil 40 is low, the impedance of the excitation coil 40 decreases. In this case, the current flowing through the excitation coil 40 increases, thereby increasing the power consumption of the sensor device 20.

[0550] 83 , the detection unit 50 detects the voltage of the third receiving coil 33 by detecting the voltage of each third linear portion 333. Furthermore, the detection unit 50 detects the voltage of the fourth receiving coil 34 by detecting the voltage of each fourth linear portion 344. Note that the detection unit 50 may detect the voltage of the third receiving coil 33 by detecting the voltage for two or more third linear portions 333. Furthermore, the detection unit 50 may detect the voltage of the fourth receiving coil 34 by detecting the voltage for two or more fourth linear portions 344.

[0551] Then, based on the detected voltages of the third receiving coil 33 and the fourth receiving coil 34, the detection unit 50 detects the displacement of the detection object in the radial direction Dr and the displacement of the detection object in the axial direction Da, as in the above-mentioned 38th embodiment.

[0552] The sensor device 20 of the 48th embodiment is configured as described above. The 48th embodiment also provides the same effects as the 38th embodiment. The 48th embodiment also provides the following effects.

[0553]

[25] The third linear portions 333 and the fourth linear portions 344 are arranged in a row at intervals in the axial direction Da.

[0554] This increases the inductance of each of the third receiving coil 33 and the fourth receiving coil 34. This makes it easier for changes to occur in the voltages generated in each of the third receiving coil 33 and the fourth receiving coil 34. This improves the sensitivity of the third receiving coil 33 and the fourth receiving coil 34. This suppresses a decrease in the detection accuracy of the displacement of the detection object in the radial direction Dr and the displacement of the detection object in the axial direction Da.

[0555] The detection unit 50 detects the voltage of the third receiving coil 33 by detecting the voltage of the third linear portion 333. Furthermore, the detection unit 50 detects the voltage of the fourth receiving coil 34 by detecting the voltage of the fourth linear portion 344.

[0556] The inductance and capacitance of the circuit including the third linear portion 333, the fourth linear portion 344, and the detection unit 50 are smaller than the inductance and capacitance of the circuit including the third receiving coil 33, the fourth receiving coil 34, and the detection unit 50. Therefore, the resonant frequency of the circuit including the third linear portion 333, the fourth linear portion 344, and the detection unit 50 is higher than the resonant frequency of the circuit including the third receiving coil 33, the fourth receiving coil 34, and the detection unit 50. This allows the frequency of the voltage applied to the excitation coil 40 to be increased. This prevents a decrease in the impedance of the excitation coil 40. This prevents an increase in the current flowing through the excitation coil 40. This prevents an increase in power consumption of the sensor device 20.

[0557] (Forty-ninth embodiment) In the forty-ninth embodiment, as shown in Fig. 84, the shape of the target 25 is different from that of the thirty-sixth embodiment. Other than this, the forty-ninth embodiment is the same as the thirty-sixth embodiment.

[0558] Specifically, instead of protruding outward in the radial direction Dr, the convex portion 252 protrudes inward in the radial direction Dr from the base portion 250 .

[0559] The sensor device 20 of the forty-ninth embodiment is configured as described above. The forty-ninth embodiment also provides the same effects as the thirty-sixth embodiment.

[0560] 85 and 86 , the 50th embodiment differs from the 36th embodiment in the shape of the target 25. The positional relationship between the target 25 and the third receiving coil 33 also differs from the 36th embodiment. Other than these, the 50th embodiment is the same as the 36th embodiment.

[0561] Specifically, instead of protruding outward in the radial direction Dr, the protrusion 252 protrudes from the base portion 250 in the axial direction Da.

[0562] Further, similarly to the thirty-sixth embodiment, the third coil outer end 336 is located further outward in the radial direction Dr than the convex portion outer end 256 in the radial direction Dr.

[0563] Furthermore, instead of being located inside the radial direction Dr of the convex portion inner end 258, the third coil inner end 338 is located outside the radial direction Dr of the convex portion inner end 258.

[0564] The sensor device 20 of the 50th embodiment is configured as described above. The 50th embodiment also provides the same effects as the 36th embodiment.

[0565] 87, the 51st embodiment differs from the 36th embodiment in the positional relationship between the target 25 and the third receiving coil 33. Other than this, the 51st embodiment is the same as the 50th embodiment.

[0566] Specifically, instead of being located outside the convex portion outer end 256 in the radial direction Dr, the third coil outer end 336 is located inside the convex portion outer end 256 in the radial direction Dr.

[0567] In addition, instead of being located outside the convex portion inner end 258 in the radial direction Dr, the third coil inner end 338 is located inside the convex portion inner end 258 in the radial direction Dr.

[0568] The sensor device 20 of the 51st embodiment is configured as described above. The 51st embodiment also provides the same effects as the 50th embodiment.

[0569] 88, the 52nd embodiment differs from the 38th embodiment in the positional relationship between the third receiver coil 33 and the fourth receiver coil 34. Other than this, the 52nd embodiment is the same as the 38th embodiment.

[0570] Specifically, the third receiving coil 33 and the fourth receiving coil 34 are aligned in the axial direction Da.

[0571] Furthermore, instead of being located outside the fourth coil outer end 346 in the radial direction Dr, the third coil inner end 338 is located inside the fourth coil outer end 346 in the radial direction Dr. That is, the fourth coil outer end 346 is located outside the third coil inner end 338 in the radial direction Dr. Therefore, the third receiving coil 33 partially overlaps with the fourth receiving coil 34 in the axial direction Da. Note that the third coil inner end 338 and the fourth coil outer end 346 are located between the convex portion outer end 256 and the convex portion inner end 258 in the radial direction Dr. Furthermore, in FIG. 88 , the fourth receiving coil 34 is indicated by a two-dot chain line to make the location of the fourth receiving coil 34 easier to understand.

[0572] The sensor device 20 of the 52nd embodiment is configured as described above. The 52nd embodiment also provides the same effects as the 38th embodiment.

[0573] 89, the fifty-third embodiment differs from the first embodiment in the shapes of the first receiver coil 31, the second receiver coil 32, the third receiver coil 33, the fourth receiver coil 34, and the excitation coil 40. Other than this, the fifty-third embodiment is the same as the first embodiment.

[0574] Here, when viewed from the axial direction Da, the line connecting the end of the excitation coil 40 facing the first receiving coil 31 in the circumferential direction Dc and the rotation axis Or is defined as Le1. The angle formed by Le1 and the first line L1 is defined as θcx1. When viewed from the axial direction Da, the line connecting the end of the excitation coil 40 facing the fourth receiving coil 34 in the circumferential direction Dc and the rotation axis Or is defined as Le2. The angle formed by Le2 and the fifth line L5 is defined as θcx2. Note that the first line L1 corresponds to the line connecting the end of the first receiving coil 31 facing the excitation coil 40 in the circumferential direction Dc and the rotation axis Or when viewed from the axial direction Da. The fifth line L5 corresponds to the line connecting the end of the fourth receiving coil 34 facing the excitation coil 40 in the circumferential direction Dc and the rotation axis Or when viewed from the axial direction Da.

[0575] The first receiving coil 31, the second receiving coil 32, the third receiving coil 33, the fourth receiving coil 34 and the excitation coil 40 are formed so that the following relational expressions (4-1) and (4-2) hold.

[0576] 0.5 × θc1 ≦ θcx1 < 180° 0.5 × θc2 ≦ θcx1 < 180° 0.5 × θc3 ≦ θcx1 < 180° 0.5 × θc4 ≦ θcx1 < 180° ... (4-1) 0.5 × θc1 ≦ θcx2 < 180° 0.5 × θc2 ≦ θcx2 < 180° 0.5 × θc3 ≦ θcx2 < 180° 0.5 × θc4 ≦ θcx2 < 180° ... (4-2)

[0577] The distance in the circumferential direction Dc from the end of the first receiving coil 31 facing the excitation coil 40 in the circumferential direction Dc to the end of the excitation coil 40 facing the first receiving coil 31 in the circumferential direction Dc is 5.0 mm or more. Furthermore, the distance in the circumferential direction Dc from the end of the fourth receiving coil 34 facing the excitation coil 40 in the circumferential direction Dc to the end of the excitation coil 40 facing the fourth receiving coil 34 in the circumferential direction Dc is 5.0 mm or more.

[0578] The sensor device 20 of the 53rd embodiment is configured as described above. The 53rd embodiment also provides the same effects as the first embodiment. The 53rd embodiment also provides the following effects.

[0579]

[26] Here, the strength of the magnetic field generated by the current increases as the distance from the point where the current flows decreases. Furthermore, when an AC voltage is applied to the excitation coil 40 from the AC voltage generating circuit 45, the excitation coil 40 generates a magnetic field that passes through each of the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, and the fourth receiving coil 34. At this time, based on the relationship between the distance from the point where the current flows and the magnetic field strength, as shown in FIG. 90, the magnetic field strength near the end of the excitation coil 40 facing the first receiving coil 31 in the circumferential direction Dc is relatively strong. Furthermore, the magnetic field strength near the end of the excitation coil 40 facing the fourth receiving coil 34 in the circumferential direction Dc is relatively strong. Furthermore, at a certain distance from the end of the excitation coil 40, the magnetic field strength generated by the excitation coil 40 becomes constant. 90, the position of the end of the excitation coil 40 that faces the first receiving coil 31 in the circumferential direction Dc is indicated as Pe1, and the position of the end of the excitation coil 40 that faces the fourth receiving coil 34 in the circumferential direction Dc is indicated as Pe2.

[0580] Therefore, when θcx1 and θcx2 are relatively small, the strength of the magnetic field generated by the excitation coil 40 and passing through each of the first, second, third, and fourth receiver coils 31, 32, 33, and 34 tends to fluctuate. This fluctuation also tends to fluctuate the voltages generated in each of the first, second, third, and fourth receiver coils 31, 32, 33, and 34 that counteract the magnetic field generated by the excitation coil 40. Therefore, the voltage waveforms of the first, second, third, and fourth receiver coils 31, 32, 33, and 34 relative to the rotation angle of the target 25 tend to be distorted. This reduces the accuracy of calculation of the rotation angles of the target 25 and the tire 12 by the detector 50. As a result, as shown in FIG. 91 , the deviation of the rotation angle from its true value relative to the rotation angle becomes relatively large.

[0581] In contrast, in the sensor device 20 of the 53rd embodiment, the first receiving coil 31, the second receiving coil 32, the third receiving coil 33, the fourth receiving coil 34 and the excitation coil 40 are formed so that the above relationship equations (4-1) and (4-2) hold.

[0582] As a result, the first receive coil 31, the second receive coil 32, the third receive coil 33, and the fourth receive coil 34 are relatively far from the ends of the excitation coil 40. Therefore, as shown in Fig. 92, the positions of the first receive coil 31, the second receive coil 32, the third receive coil 33, and the fourth receive coil 34 are positions where the strength of the magnetic field generated by the excitation coil 40 is constant. In Fig. 92, the positional range of the first receive coil 31, the second receive coil 32, the third receive coil 33, and the fourth receive coil 34 in the circumferential direction Dc is indicated as Rp_coil. The position of the end of the excitation coil 40 facing the first receive coil 31 in the circumferential direction Dc is indicated as Pe1. The end of the excitation coil 40 facing the fourth receive coil ...

Claims

1. A sensor device comprising: a conductor (25) having a base portion (250) that rotates around a rotation axis (Or) due to the rotation of a detection object (12) and that is displaced due to the displacement of the detection object, a plurality of convex portions (252) protruding from the base portion and arranged at intervals in a circumferential direction (Dc) that is a direction around the rotation axis, and concave portions (254) formed between adjacent convex portions; a first coil (31) that outputs a voltage having a periodicity corresponding to a change in a magnetic field caused by the convex portions; a second coil (32) that is arranged in the circumferential direction with the first coil and outputs a voltage having a periodicity corresponding to a change in the magnetic field caused by the convex portions, the voltage being out of phase with the voltage of the first coil; and a detection unit (50) that detects the rotation angle and displacement of the detection object based on the voltages of the first coil and the second coil.

2. A sensor device according to claim 1, wherein the first coil and the second coil face the protrusion in the direction (Da) in which the rotation axis extends.

3. A sensor device according to claim 1, wherein the first coil and the second coil face the protrusion in a direction (Dr) perpendicular to the rotation axis.

4. A sensor device according to claim 2 or 3, wherein the number of said protrusions is an odd number.

5. When viewed from the direction (Da) along which the rotation axis extends, α is the angle formed by a line connecting the rotation axis and corresponding portions of the adjacent convex portions; when viewed from the direction (Da) along which the rotation axis extends, θce is the angle formed by a line connecting the end of the first coil opposite to the second coil and the rotation axis and a line connecting the end of the second coil opposite to the first coil and the rotation axis; when viewed from the direction (Da) along which the rotation axis extends, θc1 is the angle formed by a line connecting the end of the first coil on the second coil side and the rotation axis and a line connecting the end of the first coil opposite to the second coil and the rotation axis; 4. The sensor device of claim 1, wherein the angle between a line connecting the end of the second coil on the first coil side and the rotation axis and a line connecting the end of the second coil opposite the first coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is θc2, the first coil and the second coil are formed such that α×1 / 2≦θc1<θce and α×1 / 2≦θc2<θce are satisfied.

6. The sensor device according to any one of claims 1 to 3, further comprising an excitation coil (40) surrounding the first coil and the second coil, the excitation coil generating a magnetic field that passes through the first coil and a magnetic field that passes through the second coil when an AC voltage is applied to the excitation coil.

7. The distance from the center (Mc1) of the first coil to the end of the first coil on the second coil side in the circumferential direction is the same as the distance from the center (Mc1) of the first coil to the end of the first coil opposite to the second coil in the circumferential direction; the distance from the center (Mc1) of the first coil to the outer end of the first coil in the direction perpendicular to the rotation axis is the same as the distance from the center (Mc1) of the first coil to the inner end of the first coil in the direction perpendicular to the rotation axis in the direction perpendicular to the rotation axis; the distance from the center (Mc2) of the second coil to the end of the second coil on the first coil side in the circumferential direction is the same as the distance from the center (Mc2) of the second coil to the end of the second coil opposite to the first coil in the circumferential direction; A sensor device as described in any one of claims 1 to 3, wherein the distance from the center (Mc2) of the second coil in a direction perpendicular to the rotation axis to the outer end of the second coil in a direction perpendicular to the rotation axis is the same as the distance from the center (Mc2) of the second coil in a direction perpendicular to the rotation axis to the inner end of the second coil in a direction perpendicular to the rotation axis.

8. The sensor device according to any one of claims 1 to 3, wherein the first coil and the second coil are formed in a spiral shape.

9. A sensor device as described in any one of claims 1 to 3, wherein the first coil has a plurality of first linear portions (311), which are arranged at intervals in the direction in which the rotation shaft extends (Da), and the second coil has a plurality of second linear portions (322), which are arranged at intervals in the direction in which the rotation shaft extends (Da).

10. A sensor device according to any one of claims 1 to 3, wherein the convex portion is formed in an arc shape centered on the rotation axis.

11. A sensor device as described in any one of claims 1 to 3, wherein the first coil has a plurality of first linear portions (311), which are arranged at intervals in a direction (Dr) perpendicular to the rotation axis and are formed in an arc shape centered on the rotation axis, and the second coil has a plurality of second linear portions (322), which are arranged at intervals in a direction (Dr) perpendicular to the rotation axis and are formed in an arc shape centered on the rotation axis.

12. A sensor device as described in any one of claims 1 to 3, wherein the detection unit detects displacement in the direction (Da) in which the rotation axis extends based on a value related to the difference in voltage between the first coil and the second coil.

13. A sensor device described in any one of claims 1 to 3, wherein the detection unit detects displacement in a direction (Dr) perpendicular to the rotation axis based on a value related to the sum of the voltages of the first coil and the second coil.

14. A sensor device as described in any one of claims 1 to 3, wherein the detection unit detects displacement in a direction (Da) in which the rotation axis extends and in a direction (Dr) perpendicular to the rotation axis based on a value related to the difference in voltage between the first coil and the second coil and a value related to the sum of the voltages of the first coil and the second coil.

15. The sensor device according to claim 1, comprising: a third coil (33) aligned with the first coil and the second coil in the circumferential direction, and outputting a voltage having a periodicity according to the change in the magnetic field caused by the convex portion, the voltage being out of phase with the voltage of the first coil and the second coil; and a fourth coil (34) aligned with the first coil, the second coil and the third coil in the circumferential direction, and outputting a voltage having a periodicity according to the change in the magnetic field caused by the convex portion, the voltage being out of phase with the voltage of the first coil, the second coil and the third coil; and the detection unit detects the rotation angle, the displacement in the direction in which the rotation axis extends (Da), and the displacement in a direction perpendicular to the rotation axis (Dr) based on the voltages of the first coil, the second coil, the third coil and the fourth coil.

16. The angle formed by a line connecting the rotation axis and corresponding portions of the adjacent convex portions when viewed from the direction (Da) in which the rotation axis extends is defined as α; the line connecting the center of the first coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a first center line (LM1); the line connecting the center of the second coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a second center line (LM2); the line connecting the center of the third coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a third center line (LM3); the line connecting the center of the fourth coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a fourth center line (LM4); the angle formed by the first center line and the second center line is defined as a first inter-coil angle (θ12); The sensor device of claim 15, wherein the angle between the first center line and the third center line is a second inter-coil angle (θ13), the angle between the first center line and the fourth center line is a third inter-coil angle (θ14), and where n1, n2, and n3 are integers greater than or equal to 0, the first inter-coil angle is an angle related to (n1 + 1 / 2) × α, the second inter-coil angle is an angle related to (n2 + 1 / 4) × α, and the third inter-coil angle is an angle related to (n3 + 3 / 4) × α.

17. A sensor device as described in claim 15 or 16, wherein the detection unit detects the rotation angle based on a value relating to the difference in voltage between the first coil and the second coil and a value relating to the difference in voltage between the third coil and the fourth coil.

18. A sensor device as described in claim 15 or 16, wherein the detection unit detects displacement in the direction (Da) in which the rotation axis extends based on a value relating to the difference in voltage between the first coil and the second coil and a value relating to the difference in voltage between the third coil and the fourth coil.

19. A sensor device as described in claim 18, wherein the detection unit detects displacement in the direction (Da) in which the rotation axis extends based on a value related to the difference in voltage between the third coil and the fourth coil when the absolute value of the difference in voltage between the first coil and the second coil is equal to or less than a threshold value.

20. A sensor device as described in claim 18, wherein the detection unit detects displacement in the direction (Da) in which the rotation axis extends based on a value related to the difference in voltage between the first coil and the second coil when the absolute value of the difference in voltage between the third coil and the fourth coil is equal to or less than a threshold value.

21. A sensor device according to claim 15 or 16, wherein the first coil, the second coil, the third coil and the fourth coil are connected in series.

22. A sensor device as described in claim 15 or 16, wherein one end of the first coil is connected in series with one end of the second coil, the other end of the second coil is connected in series with one end of the third coil, and the other end of the third coil is connected in series with one end of the fourth coil, and the detection unit detects displacement in a direction (Dr) perpendicular to the rotation axis based on a value related to the difference in voltage between the first coil and the fourth coil.

23. The angle formed by a line connecting the rotation axis and corresponding portions of the adjacent convex portions when viewed from the direction (Da) in which the rotation axis extends is defined as α; the line connecting the center of the first coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a first center line (LM1); the line connecting the center of the second coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a second center line (LM2); the line connecting the center of the third coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a third center line (LM3); the line connecting the center of the fourth coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a fourth center line (LM4); the angle formed by the first center line and the second center line is defined as a first inter-coil angle (θ12); The sensor device of claim 15, wherein an angle between the first center line and the third center line is a second inter-coil angle (θ13), and an angle between the first center line and the fourth center line is a third inter-coil angle (θ14), the first inter-coil angle is an angle related to 3 / 4 x α, the second inter-coil angle is an angle related to 6 / 4 x α, and the third inter-coil angle is an angle related to 9 / 4 x α.

24. The number of the protrusions is an odd number, and when viewed from the direction in which the rotation axis extends (Da), the angle formed by a line connecting the corresponding parts of the adjacent protrusions and the rotation axis is defined as α, when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the first coil and the rotation axis is defined as a first center line (LM1), when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the second coil and the rotation axis is defined as a second center line (LM2), when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the third coil and the rotation axis is defined as a third center line (LM3), and when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the fourth coil and the rotation axis is defined as a fourth center line (LM4), The sensor device of claim 15, wherein the angle between the first center line and the second center line is a first inter-coil angle (θ12), the angle between the first center line and the third center line is a second inter-coil angle (θ13), and the angle between the third center line and the fourth center line is a third inter-coil angle (θ34), the first inter-coil angle is an angle related to 1 / 2 x α, the second inter-coil angle is an angle related to 90°, and the third inter-coil angle is an angle related to 1 / 2 x α, and the detection unit detects a displacement in one direction in a direction (Dr) perpendicular to the rotation axis based on a voltage difference between the first coil and the second coil, and detects a displacement in a direction perpendicular to the rotation axis and the one direction based on a voltage difference between the third coil and the fourth coil.

25. The number of the protrusions is an odd number, and when viewed from the direction in which the rotation axis extends (Da), the angle formed by a line connecting the corresponding parts of the adjacent protrusions and the rotation axis is defined as α, when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the first coil and the rotation axis is defined as a first center line (LM1), when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the second coil and the rotation axis is defined as a second center line (LM2), when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the third coil and the rotation axis is defined as a third center line (LM3), and when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the fourth coil and the rotation axis is defined as a fourth center line (LM4), 16. The sensor device of claim 15, wherein: an angle between the first center line and the second center line is a first inter-coil angle (θ12); an angle between the first center line and the third center line is a second inter-coil angle (θ13); and an angle between the third center line and the fourth center line is a third inter-coil angle (θ34); the first inter-coil angle is an angle related to 3 / 4 x α; the second inter-coil angle is an angle related to 180°; and the third inter-coil angle is an angle related to 3 / 4 x α; and the detection unit detects an inclination angle of the conductor with respect to a direction perpendicular to the rotation axis and a displacement of the detection target in a direction (Da) in which the rotation axis extends based on a value related to a voltage difference between the first coil and the second coil and a value related to a voltage difference between the third coil and the fourth coil.

26. The number of the protrusions is an even number, and when viewed from the direction in which the rotation axis extends (Da), the angle formed by a line connecting the corresponding parts of the adjacent protrusions and the rotation axis is defined as α, when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the first coil and the rotation axis is defined as a first center line (LM1), when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the second coil and the rotation axis is defined as a second center line (LM2), when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the third coil and the rotation axis is defined as a third center line (LM3), and when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the fourth coil and the rotation axis is defined as a fourth center line (LM4), the angle between the first center line and the second center line is a first inter-coil angle (θ12), the angle between the first center line and the third center line is a second inter-coil angle (θ13), and the angle between the third center line and the fourth center line is a third inter-coil angle (θ34), the first inter-coil angle is an angle related to 3 / 4 x α, the second inter-coil angle is an angle related to 180° + 1 / 2 x α, and the third inter-coil angle is an angle related to 3 / 4 x α, and the detection unit detects the inclination angle of the conductor with respect to a direction perpendicular to the rotation axis and the displacement of the detection target in the direction (Da) in which the rotation axis extends based on a value related to a voltage difference between the first coil and the second coil and a value related to a voltage difference between the third coil and the fourth coil.

27. A sensor device as described in any one of claims 1 to 3, wherein the detection unit detects the inclination angle of the conductor with respect to a direction perpendicular to the rotation axis and the displacement of the detection object in the direction (Da) in which the rotation axis extends based on the difference between the voltage of the first coil at the current time and the voltage of the first coil prior to the current time, and the difference between the voltage of the second coil at the current time and the voltage of the second coil prior to the current time.

28. The number of the protrusions is an odd number, a straight line connecting the center of the first coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a first center line (LM1), a straight line connecting the center of the second coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a second center line (LM2), a straight line connecting the center of the third coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a third center line (LM3), a straight line connecting the center of the fourth coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a fourth center line (LM4), an angle formed by the first center line and the second center line is defined as a first inter-coil angle (θ12), and an angle formed by the first center line and the third center line is defined as a second inter-coil angle (θ13), The sensor device of claim 15, wherein, if the angle between the first center line and the fourth center line is a third inter-coil angle (θ14), the first inter-coil angle is an angle relative to 180°, the second inter-coil angle is an angle relative to 90°, and the third inter-coil angle is an angle relative to 270°, and the detection unit detects the inclination angle of the conductor with respect to one direction perpendicular to the rotation axis and the inclination angle of the conductor with respect to the direction perpendicular to the rotation axis and the one direction based on the voltages of the first coil, the second coil, the third coil, and the fourth coil.

29. The number of the protrusions is an odd number, and when viewed from the direction in which the rotation axis extends (Da), an angle formed by a line connecting the rotation axis and corresponding parts of adjacent protrusions is defined as α, a line connecting the center of the first coil and the rotation axis when viewed from the direction in which the rotation axis extends (Da) is defined as a first center line (LM1), a line connecting the center of the second coil and the rotation axis when viewed from the direction in which the rotation axis extends (Da) is defined as a second center line (LM2), a line connecting the center of the third coil and the rotation axis when viewed from the direction in which the rotation axis extends (Da) is defined as a third center line (LM3), and a line connecting the center of the fourth coil and the rotation axis when viewed from the direction in which the rotation axis extends (Da) is defined as a fourth center line (LM4), The sensor device of claim 15, wherein the angle between the first center line and the second center line is a first inter-coil angle (θ12), the angle between the first center line and the third center line is a second inter-coil angle (θ13), and the angle between the third center line and the fourth center line is a third inter-coil angle (θ34), the first inter-coil angle is an angle related to 90°-3 / 4×α, the second inter-coil angle is an angle related to 90°, and the third inter-coil angle is an angle related to 90°-3 / 4×α, and the detection unit detects the inclination angle of the conductor with respect to one direction perpendicular to the rotation axis and the inclination angle of the conductor with respect to the direction perpendicular to the rotation axis and the one direction based on the voltages of the first coil, the second coil, the third coil, and the fourth coil.

30. The sensor device comprises: a fifth coil (35) arranged in the circumferential direction with the first coil, the second coil, the third coil, and the fourth coil, and outputting a voltage having a periodicity according to a change in the magnetic field caused by the convex portion, the voltage having the same phase as the voltage of the second coil; a sixth coil (36) arranged in the circumferential direction with the first coil, the second coil, the third coil, the fourth coil, and the fifth coil, and outputting a voltage having a periodicity according to a change in the magnetic field caused by the convex portion, the voltage having the same phase as the voltage of the first coil; and a seventh coil (37) arranged in the circumferential direction with the first coil, the second coil, the third coil, the fourth coil, the fifth coil, and the sixth coil, and outputting a voltage having a periodicity according to a change in the magnetic field caused by the convex portion, the voltage having the same phase as the voltage of the fourth coil. an eighth coil (38) that is aligned with the first coil, the second coil, the third coil, the fourth coil, the fifth coil, the sixth coil, and the seventh coil in the circumferential direction and outputs a voltage that has a periodicity according to a change in the magnetic field that changes due to the convex portion and that has the same phase as the voltage of the third coil; wherein the detection unit detects the rotation angle, the displacement in the direction in which the rotation axis extends (Da), and the displacement in the direction perpendicular to the rotation axis (Dr) based on the voltages of the first coil, the second coil, the third coil, the fourth coil, the fifth coil, the sixth coil, the seventh coil, and the eighth coil.

31. The number of the protrusions is an odd number, and when viewed from the direction in which the rotation axis extends (Da), the angle formed by a line connecting the corresponding parts of the adjacent protrusions and the rotation axis is defined as α, when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the first coil and the rotation axis is defined as a first center line (LM1), when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the second coil and the rotation axis is defined as a second center line (LM2), when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the third coil and the rotation axis is defined as a third center line (LM3), and when viewed from the direction in which the rotation axis extends (Da), the line connecting the center of the fourth coil and the rotation axis is defined as a fourth center line (LM4), a fifth center line (LM5) is a straight line connecting the center of the fifth coil and the rotation axis when viewed from the direction (Da) that the rotation axis extends; a sixth center line (LM6) is a straight line connecting the center of the sixth coil and the rotation axis when viewed from the direction (Da) that the rotation axis extends; a seventh center line (LM7) is a straight line connecting the center of the seventh coil and the rotation axis when viewed from the direction (Da) that the rotation axis extends; and an eighth center line (LM8) is a straight line connecting the center of the eighth coil and the rotation axis when viewed from the direction (Da) that the rotation axis extends; an angle formed by the first center line and the second center line is an angle related to 1 / 2×α; an angle formed by the first center line and the third center line is an angle related to 90°; and an angle formed by the second center line and the fourth center line is an angle related to 90°. an angle between the first center line and the fifth center line is an angle of 180°, an angle between the second center line and the sixth center line is an angle of 180°, an angle between the first center line and the seventh center line is an angle of 270°, and an angle between the second center line and the eighth center line is an angle of 270°,The sensor device of claim 30, wherein the detection unit detects the inclination angle of the conductor with respect to a direction perpendicular to the rotation axis and the inclination angle of the conductor with respect to a direction perpendicular to the rotation axis and the direction perpendicular to the rotation axis based on the voltages of the first coil, the second coil, the third coil, the fourth coil, the fifth coil, the sixth coil, the seventh coil and the eighth coil.

32. The number of the protrusions is an odd number, and when viewed from the direction (Da) of the rotation axis, the angle formed by a line connecting corresponding parts of adjacent protrusions and the rotation axis is defined as α, when viewed from the direction (Da) of the rotation axis, the line connecting the center of the first coil and the rotation axis is defined as a first center line (LM1), when viewed from the direction (Da) of the rotation axis, the line connecting the center of the second coil and the rotation axis is defined as a second center line (LM2), when viewed from the direction (Da) of the rotation axis, the line connecting the center of the third coil and the rotation axis is defined as a third center line (LM3), and when viewed from the direction (Da) of the rotation axis, the line connecting the center of the fourth coil and the rotation axis is defined as a fourth center line (LM4), a fifth center line (LM5) is a line connecting the center of the fifth coil and the rotation axis when viewed from the direction (Da) that the rotation axis extends; a sixth center line (LM6) is a line connecting the center of the sixth coil and the rotation axis when viewed from the direction (Da) that the rotation axis extends; a seventh center line (LM7) is a line connecting the center of the seventh coil and the rotation axis when viewed from the direction (Da) that the rotation axis extends; and an eighth center line (LM8) is a line connecting the center of the eighth coil and the rotation axis when viewed from the direction (Da) that the rotation axis extends; an angle between the first center line and the second center line is an angle related to 3 / 4×α; an angle between the first center line and the third center line is an angle related to 90°; an angle between the first center line and the fourth center line is an angle related to 180°, an angle between the first center line and the fifth center line is an angle related to 270°, an angle between the second center line and the sixth center line is an angle related to 90°, an angle between the second center line and the eighth center line is an angle related to 180°, and an angle between the second center line and the seventh center line is an angle related to 270°,The sensor device of claim 30, wherein the detection unit detects the inclination angle of the conductor with respect to a direction perpendicular to the rotation axis and the inclination angle of the conductor with respect to a direction perpendicular to the rotation axis and the direction perpendicular to the rotation axis based on the voltages of the first coil, the second coil, the third coil, the fourth coil, the fifth coil, the sixth coil, the seventh coil and the eighth coil.

33. A sensor device as described in claim 15 or 16, wherein a value relating to the difference between the voltage of the first coil and the voltage of the second coil is a first voltage difference (ΔVc12), and a value relating to the difference between the voltage of the third coil and the voltage of the fourth coil is a second voltage difference (ΔVc34), and the detection unit detects a displacement in a direction (Da) in which the rotation axis extends and a displacement in a direction (Dr) perpendicular to the rotation axis based on the first voltage difference and the second voltage difference.

34. The sensor device of claim 33, wherein the detection unit: detects the rotation angle based on the first voltage difference and the second voltage difference; corrects the first voltage difference and the second voltage difference using a mathematical optimization method to increase the accuracy of the rotation angle compared to before correction; calculates a value related to an ellipse based on the corrected first voltage difference and the second voltage difference (X, Y); and detects a displacement in a direction in which the rotation axis extends (Da) and a displacement in a direction perpendicular to the rotation axis (Dr) based on the major axis and minor axis of the ellipse.

35. The sensor device of claim 33, wherein the detection unit detects the rotation angle based on the first voltage difference and the second voltage difference, corrects the first voltage difference and the second voltage difference using a mathematical optimization method to increase the accuracy of the rotation angle compared to before correction, and detects a displacement in a direction (Da) in which the rotation axis extends and a displacement in a direction (Dr) perpendicular to the rotation axis based on peak values ​​of the corrected first voltage difference and the second voltage difference (X, Y) with respect to the rotation angle.

36. The sensor device further includes an excitation coil (40) surrounding the first coil and the second coil, and when an AC voltage is applied to the excitation coil, the excitation coil generates a magnetic field passing through the first coil and generates a magnetic field passing through the second coil, and when viewed from the direction (Da) along which the rotation axis extends, the angle formed by a line connecting the end of the first coil on the second coil side and the rotation axis and a line connecting the end of the first coil opposite to the second coil and the rotation axis is defined as θc1, and when viewed from the direction (Da) along which the rotation axis extends, the angle formed by a line connecting the end of the second coil on the first coil side and the rotation axis and a line connecting the end of the second coil opposite to the first coil and the rotation axis is defined as θc2, The sensor device of claim 1, wherein the angle formed by a line connecting an end of the first coil facing the excitation coil in the circumferential direction and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is θcx1, and an angle formed by a line connecting an end of the excitation coil facing the first coil in the circumferential direction and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is θcx2, and an angle formed by a line connecting an end of the second coil facing the excitation coil in the circumferential direction and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is θcx2, the first coil, the second coil and the excitation coil are formed so that the following relationships are satisfied: 0.5×θc1≦θcx1 0.5×θc2≦θcx1 0.5×θc1≦θcx2 0.5×θc2≦θcx2 37. A sensor device as described in claim 36, wherein the distance in the circumferential direction from an end of the first coil that faces the excitation coil in the circumferential direction to an end of the excitation coil that faces the first coil in the circumferential direction is 5.0 mm or more, and the distance in the circumferential direction from an end of the second coil that faces the excitation coil in the circumferential direction to an end of the excitation coil that faces the second coil in the circumferential direction is 5.0 mm or more.

38. The sensor device comprises: a third coil (33) arranged in the circumferential direction with the first coil and the second coil, and outputting a voltage having a periodicity according to a change in the magnetic field caused by the convex portion, the voltage having a different phase from the voltage of the first coil and the second coil; a fourth coil (34) arranged in the circumferential direction with the first coil, the second coil, and the third coil, and outputting a voltage having a periodicity according to a change in the magnetic field caused by the convex portion, the voltage having a different phase from the voltage of the first coil, the second coil, and the third coil; and an excitation coil (40) surrounding the first coil, the second coil, the third coil, and the fourth coil; and the detection unit detects the rotation angle, the displacement in the direction in which the rotation axis extends (Da), and the displacement in the direction perpendicular to the rotation axis (Dr) based on the voltages of the first coil, the second coil, the third coil, and the fourth coil; When an AC voltage is applied to the excitation coil, the excitation coil generates a magnetic field passing through each of the first coil, the second coil, the third coil, and the fourth coil, the first coil, the second coil, the third coil, and the fourth coil are arranged in order in the circumferential direction, when viewed from the direction (Da) in which the rotation axis extends, an angle formed by a line connecting an end of the first coil on the second coil side and the rotation axis and a line connecting an end of the first coil opposite to the second coil and the rotation axis is defined as θc1, when viewed from the direction (Da) in which the rotation axis extends, an angle formed by a line connecting an end of the second coil on the first coil side and the rotation axis and a line connecting an end of the second coil opposite to the first coil and the rotation axis is defined as θc2, When viewed from a direction (Da) in which the rotation axis extends, an angle formed by a line connecting an end of the third coil on the side of the fourth coil and the rotation axis and a line connecting an end of the third coil opposite to the fourth coil and the rotation axis is defined as θc3,When viewed from the direction (Da) along which the rotation axis extends, an angle formed by a line connecting an end of the fourth coil on the third coil side and the rotation axis and a line connecting an end of the fourth coil opposite the third coil and the rotation axis is defined as θc4; when viewed from the direction (Da) along which the rotation axis extends, an angle formed by a line connecting an end of the first coil facing the excitation coil in the circumferential direction and the rotation axis and a line connecting an end of the excitation coil facing the first coil in the circumferential direction and the rotation axis is defined as θcx1; and when viewed from the direction (Da) along which the rotation axis extends, an angle formed by a line connecting an end of the fourth coil facing the excitation coil in the circumferential direction and the rotation axis and a line connecting an end of the excitation coil facing the fourth coil in the circumferential direction and the rotation axis is defined as θcx2. The sensor device according to claim 1, wherein the first coil, the second coil, the third coil, the fourth coil and the excitation coil are formed so that the following relationships hold: 0.5 x θc1 < θcx1 0.5 x θc2 < θcx1 0.5 x θc3 < θcx1 0.5 x θc4 < θcx1 0.5 x θc1 < θcx2 0.5 x θc2 < θcx2 0.5 x θc3 < θcx2 0.5 x θc4 < θcx2 39. The sensor device as described in claim 1, wherein the convex portion protrudes from the base portion in an axial direction (Da), which is the direction in which the rotation axis extends, and has a convex portion outer end (256) which is the outer end in a direction (Dr) perpendicular to the axial direction, and a convex portion inner end (258) which is the inner end in the direction (Dr) perpendicular to the axial direction.

40. A sensor device as described in claim 1, wherein the convex portion protrudes outward from the base portion in a direction (Dr) perpendicular to an axial direction (Da) in which the rotation axis extends, and has a convex portion outer end (256) which is the outer end in the direction (Dr) perpendicular to the axial direction.

41. A sensor device as described in claim 1, wherein the convex portion protrudes inward from the base portion in a direction (Dr) perpendicular to an axial direction (Da) in which the rotation axis extends, and has a convex portion inner end (258) which is the inner end in the direction (Dr) perpendicular to the axial direction.

42. A sensor device as described in claim 39 or 40, wherein the first coil has a first coil outer end (316) that is an outer end in a direction perpendicular to the axial direction, the second coil has a second coil outer end (326) that is an outer end in a direction perpendicular to the axial direction, the convex outer end is located outer than the first coil outer end and the second coil outer end in the direction perpendicular to the axial direction, the distance (Lcp1_outer) from the first coil outer end to the convex outer end in the direction perpendicular to the axial direction is greater than 0 mm and not greater than 1.0 mm, and the distance (Lcp2_outer) from the second coil outer end to the convex outer end in the direction perpendicular to the axial direction is greater than 0 mm and not greater than 1.0 mm.

43. A sensor device as described in claim 39 or 41, wherein the first coil has a first coil inner end (318) that is an inner end in a direction perpendicular to the axial direction, the second coil has a second coil inner end (328) that is an inner end in a direction perpendicular to the axial direction, the inner end of the convex portion is located more inward in the direction perpendicular to the axial direction than the inner ends of the first coil and the second coil, the distance (Lcp1_inner) from the inner end of the first coil to the inner end of the convex portion in the direction perpendicular to the axial direction is greater than 0 mm and less than 1.0 mm, and the distance (Lcp2_inner) from the inner end of the second coil to the inner end of the convex portion in the direction perpendicular to the axial direction is greater than 0 mm and less than 1.0 mm.

44. A sensor device as described in claim 39 or 40, wherein the first coil has a first coil outer end (316) that is an outer end in a direction perpendicular to the axial direction, the second coil has a second coil outer end (326) that is an outer end in a direction perpendicular to the axial direction, the convex outer end is located outer than the first coil outer end and the second coil outer end in the direction perpendicular to the axial direction, the distance (Lcp1_outer) from the first coil outer end to the convex outer end in the direction perpendicular to the axial direction is 3.0 mm or more, and the distance (Lcp2_outer) from the second coil outer end to the convex outer end in the direction perpendicular to the axial direction is 3.0 mm or more.

45. A sensor device as described in claim 39 or 41, wherein the first coil has a first coil inner end (318) that is an inner end in a direction perpendicular to the axial direction, the second coil has a second coil inner end (328) that is an inner end in a direction perpendicular to the axial direction, the inner end of the convex portion is located more inward in the direction perpendicular to the axial direction than the inner ends of the first coil and the second coil, the distance (Lcp1_inner) from the inner end of the first coil to the inner end of the convex portion in the direction perpendicular to the axial direction is 3.0 mm or more, and the distance (Lcp2_inner) from the inner end of the second coil to the inner end of the convex portion in the direction perpendicular to the axial direction is 3.0 mm or more.

46. ​​A sensor device as described in claim 39 or 40, wherein the first coil has a first coil outer end (316) that is an outer end in a direction perpendicular to the axial direction, the second coil has a second coil outer end (326) that is an outer end in a direction perpendicular to the axial direction, the convex outer end is located more inward in the direction perpendicular to the axial direction than the first coil outer end and the second coil outer end, the distance (Lcp1_outer) from the first coil outer end to the convex outer end in the direction perpendicular to the axial direction is 3.0 mm or more and 5.0 mm or less, and the distance (Lcp2_outer) from the second coil outer end to the convex outer end in the direction perpendicular to the axial direction is 3.0 mm or more and 5.0 mm or less.

47. A sensor device as described in claim 39 or 41, wherein the first coil has a first coil inner end (318) that is an inner end in a direction perpendicular to the axial direction, the second coil has a second coil inner end (328) that is an inner end in a direction perpendicular to the axial direction, the inner end of the convex portion is located outer than the inner ends of the first coil and the second coil in the direction perpendicular to the axial direction, the distance (Lcp1_inner) from the inner end of the first coil to the inner end of the convex portion in the direction perpendicular to the axial direction is 3.0 mm or more and 5.0 mm or less, and the distance (Lcp2_inner) from the inner end of the second coil to the inner end of the convex portion in the direction perpendicular to the axial direction is 3.0 mm or more and 5.0 mm or less.

48. The first coil and the second coil are formed in a spiral shape extending on a plane perpendicular to the rotation axis, the first coil has a plurality of first linear portions (311), the first linear portions are arranged at intervals in the circumferential direction, the second coil has a plurality of second linear portions (322), the second linear portions are arranged at intervals in the circumferential direction, the first linear portion closest to the center (Mc1) of the first coil is defined as a most central first linear portion (3110), and the second linear portion closest to the center (Mc2) of the second coil is defined as a most central second linear portion (3220), the most central first linear portions face each other in the circumferential direction, and the most central second linear portions face each other in the circumferential direction, The sensor device of claim 1, wherein the distance between the centermost first linear portions in the circumferential direction is Lc1, the shortest distance in the circumferential direction between the first linear portions adjacent to each other in the circumferential direction is Pc1, the distance between the centermost second linear portions in the circumferential direction is Lc2, and the shortest distance in the circumferential direction between the second linear portions adjacent to each other in the circumferential direction is Pc2, the first coil and the second coil are formed such that: 1≦Lc1 / Pc1≦10 1≦Lc2 / Pc2≦10.

49. The first coil has a first coil outer end (316) which is an outer end in a direction perpendicular to the axial direction, the second coil has a second coil outer end (326) which is an outer end in a direction perpendicular to the axial direction, the first coil outer end and the second coil outer end are located outer than the convex outer end in the direction perpendicular to the axial direction, the convex outer end moves outward in the direction perpendicular to the axial direction (Dr) when the detection object is displaced outward in the direction perpendicular to the axial direction (Dr), and if the movement range of the convex outer end when it moves outward in the direction perpendicular to the axial direction (Dr) is an outer end movement range (Ro), then The sensor device described in claim 39 or 40, wherein, in a portion of the first coil that overlaps with the outer end moving range in the axial direction, the proportion of the volume of the first coil within a predetermined range (Rp) smaller than the outer end moving range is greater than the proportion of the volume of the first coil within the predetermined range in a portion of the first coil that does not overlap with the outer end moving range in the axial direction, and the proportion of the volume of the second coil within the predetermined range in a portion of the second coil that overlaps with the outer end moving range in the axial direction is greater than the proportion of the volume of the second coil within the predetermined range in a portion of the second coil that does not overlap with the outer end moving range in the axial direction.

50. A sensor device as described in claim 39 or 41, wherein the inner end of the convex portion moves outward in a direction perpendicular to the axial direction (Dr) when the detection target is displaced outward in the direction perpendicular to the axial direction (Dr), and the range of movement when the inner end of the convex portion moves outward in the direction perpendicular to the axial direction (Dr) is defined as an inner end movement range (Ri), in a portion of the first coil that overlaps with the inner end movement range in the axial direction, the proportion of the volume of the first coil within a predetermined range (Rp) smaller than the inner end movement range is greater than the proportion of the volume of the first coil within the predetermined range in a portion of the first coil that does not overlap with the inner end movement range in the axial direction, and the proportion of the volume of the second coil within the predetermined range in a portion of the second coil that overlaps with the inner end movement range in the axial direction is greater than the proportion of the volume of the second coil within the predetermined range in a portion of the second coil that does not overlap with the inner end movement range in the axial direction.

51. The sensor device according to claim 1, wherein the conductor has an insulating portion (260) disposed between the base portion and the protruding portion and having electrical insulation properties.

52. Let the distance from the rotation axis to the center (Mc1) of the first coil in the direction (Dr) perpendicular to the rotation axis be a first center distance (r1), let the distance from the rotation axis to the center (Mc2) of the second coil in the direction (Dr) perpendicular to the rotation axis be a second center distance (r2), let a straight line that passes through the rotation axis and is perpendicular to the rotation axis be a reference line (Lb1), let a straight line that connects the center of the first coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends be a first center line (LM1), let the angle between the first center line and the reference line be a first central angle (θco1), let a straight line that connects the center of the second coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends be a second center line (LM2), and let the angle between the second center line and the reference line be a second central angle (θco2), 2. The sensor device according to claim 1, wherein the detection unit detects a tilt angle of the conductor with respect to the reference line, the tilt angle being a tilt angle with respect to a direction perpendicular to the rotation axis, based on a value related to the first center distance, a value related to the second center distance, a value related to the first central angle, a value related to the second central angle, a value related to a change in voltage of the first coil with respect to the rotation angle, and a value related to a change in voltage of the second coil with respect to the rotation angle.

53. The sensor device includes a third coil (33) that is aligned with the first coil and the second coil in the circumferential direction and outputs a voltage having a periodicity corresponding to a change in the magnetic field caused by the convex portion, and the reference line is a first reference line, and a straight line that passes through the rotation axis and is perpendicular to the rotation axis and the first reference line is a second reference line (Lb2), a distance from the rotation axis to the center (Mc3) of the third coil in a direction (Dr) perpendicular to the rotation axis is a third center distance (r3), a straight line that connects the center of the third coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is a third center line (LM3), and an angle formed by the third center line and the first reference line is a third central angle (θco3), the detection unit is 53. The sensor device of claim 52, further comprising: a sensor device for detecting a tilt angle of the conductor with respect to the first reference line, the tilt angle being a tilt angle with respect to a direction perpendicular to the rotation axis, based on a value related to the first center distance, a value related to the second center distance, a value related to the third center distance, a value related to the first central angle, a value related to the second central angle, a value related to the third central angle, a value related to the change in voltage of the first coil with respect to the rotation angle, a value related to the change in voltage of the second coil with respect to the rotation angle, and a value related to the change in voltage of the third coil with respect to the rotation angle.

54. The sensor device comprises: a third coil (33) arranged in the circumferential direction with the first coil and the second coil, outputting a voltage having a periodicity according to a change in the magnetic field caused by the convex portion, the voltage having a different phase from the voltages of the first coil and the second coil; and a fourth coil (34) arranged in the circumferential direction with the first coil, the second coil, and the third coil, outputting a voltage having a periodicity according to a change in the magnetic field caused by the convex portion, the voltage having a different phase from the voltages of the first coil, the second coil, and the third coil; the detection unit detects the rotation angle, the displacement in the direction (Da) in which the rotation axis extends, and the displacement in the direction (Dr) perpendicular to the rotation axis based on the voltages of the first coil, the second coil, the third coil, and the fourth coil; and α is an angle formed by a straight line connecting the rotation axis and corresponding parts of the adjacent convex portions when viewed from the direction (Da) in which the rotation axis extends; a straight line connecting the center of the first coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a first center line (LM1); a straight line connecting the center of the second coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a second center line (LM2); a straight line connecting the center of the third coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a third center line (LM3); a straight line connecting the center of the fourth coil and the rotation axis when viewed from the direction (Da) in which the rotation axis extends is defined as a fourth center line (LM4); an angle formed by the first center line and the second center line is defined as a first inter-coil angle (θ12); and an angle formed by the third center line and the fourth center line is defined as a second inter-coil angle (θ34), the first inter-coil angle is greater than or equal to ¼ × α and less than α, the second coil angle is greater than or equal to ¼×α and less than or equal to α, the center between the center (Mc1) of the first coil and the center (Mc2) of the second coil in the direction perpendicular to the rotation axis and the circumferential direction is defined as a first intermediate center (Mc12), and the distance from the rotation axis to the first intermediate center in the direction (Dr) perpendicular to the rotation axis is defined as a first intermediate distance (rb1),Let the center between the center of the third coil (Mc3) and the center of the fourth coil (Mc4) in the direction perpendicular to the rotation axis and in the circumferential direction be a second intermediate center (Mc34), let the distance from the rotation axis to the second intermediate center in the direction perpendicular to the rotation axis (Dr) be a second intermediate distance (rb2), let a straight line that passes through the rotation axis and is perpendicular to the rotation axis be a reference line (Lb1), let a straight line that connects the first intermediate center and the rotation axis when viewed from the direction in which the rotation axis extends (Da) be a first intermediate line (LMb1), let the angle between the first intermediate line and the reference line be a first intermediate angle (θcb1), let a straight line that connects the second intermediate center and the rotation axis when viewed from the direction in which the rotation axis extends (Da) be a second intermediate line (LMb2), and let the angle between the second intermediate line and the reference line be a second intermediate angle (θcb2), 2. The sensor device according to claim 1, wherein the detection unit detects a tilt angle of the conductor relative to the reference line, which is a tilt angle with respect to a direction perpendicular to the rotation axis, based on a value related to the first intermediate distance, a value related to the second intermediate distance, a value related to the first intermediate angle, a value related to the second intermediate angle, a value related to a difference in voltage between the first coil and the second coil, and a value related to a difference in voltage between the third coil and the fourth coil.

55. The sensor device comprises a fifth coil (35) arranged in the circumferential direction with the first coil, the second coil, the third coil, and the fourth coil, and outputting a voltage having a periodicity according to a change in the magnetic field caused by the convex portion; and a sixth coil (36) arranged in the circumferential direction with the first coil, the second coil, the third coil, the fourth coil, and the fifth coil, and outputting a voltage having a periodicity according to a change in the magnetic field caused by the convex portion and having a phase different from that of the voltage of the fifth coil, wherein a fifth center line (LM5) is a straight line connecting the center of the fifth coil and the rotation axis when viewed from the direction in which the rotation axis extends (Da), a sixth center line (LM6) is a straight line connecting the center of the sixth coil and the rotation axis when viewed from the direction in which the rotation axis extends (Da), and a third inter-coil angle (θ56) is an angle between the fifth center line and the sixth center line. the third inter-coil angle is greater than or equal to ¼×α and less than or equal to α, the reference line is a first reference line, and a straight line that passes through the rotation axis and is perpendicular to the rotation axis and the first reference line is defined as a second reference line (Lb2), the center between the center of the fifth coil (Mc5) and the center of the sixth coil (Mc6) in a direction perpendicular to the rotation axis and in the circumferential direction is defined as a third intermediate center (Mc56), the distance from the rotation axis to the third intermediate center in a direction perpendicular to the rotation axis (Dr) is defined as a third intermediate distance (rb3), a straight line connecting the third intermediate center and the rotation axis when viewed from a direction in which the rotation axis extends (Da) is defined as a third intermediate line (LMb3), and the angle formed by the third intermediate line and the first reference line is defined as a third intermediate angle (θcb3), the detection unit: based on a value for the first intermediate distance, a value for the second intermediate distance, a value for the third intermediate distance, a value for the first intermediate angle, a value for the second intermediate angle, a value for the third intermediate angle, a value for a difference in voltage between the first coil and the second coil, a value for a difference in voltage between the third coil and the fourth coil, and a value for a difference in voltage between the fifth coil and the sixth coil,55. The sensor device of claim 54, further comprising: a tilt angle of the conductor relative to the first reference line, the tilt angle being a tilt angle with respect to a direction perpendicular to the rotation axis; and a tilt angle of the conductor relative to the second reference line, the tilt angle being a tilt angle with respect to a direction perpendicular to the rotation axis.

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