Position detection device

Abstract

The invention provides a position detection device capable of detecting the position of a shaft moving forward and backward in the axial direction with high precision. A position detection device (1) that detects the position of a rack shaft (13) that moves forward and backward in the axial direction within a predetermined movement range is provided with: an excitation coil (4) that generates an alternating-current magnetic field; and a detection body (2) that moves integrally with the rack shaft (13) and interlinks with the magnetic flux of the alternating-current magnetic field. And a first detection coil (5) having a detection unit (51) facing the detection body (2) while the rack shaft (13) moves from the moving end on one side in the axial direction to the moving end on the other side in the axial direction. The induced voltage induced in the detection unit (51) by the magnetic flux of the AC magnetic field changes in accordance with the position of the detection body (2) with respect to the detection unit (51). The first detection coil (5) has adjustment units (52, 53) that suppress the influence of the inclination of the rack shaft (13) with respect to the detection unit (51) on the induced voltage induced by the detection unit (51).

Description

Technical Field

[0001] The present invention relates to a position detection device for detecting the position of a shaft that moves axially forward and backward within a predetermined moving range. Background Art

[0002] Currently, a position detection device for detecting the position of a shaft that moves axially forward and backward is used, for example, to detect the position of a rack shaft in a steering device of a vehicle.

[0003] The detection unit described in Patent Document 1 detects the axial position of a rack shaft of an electric power steering device, and includes a DC power supply, a permanent magnet, a group of elements composed of a first magnetoresistive element to a fourth magnetoresistive element disposed between the permanent magnet and the rack shaft, and an arithmetic unit that calculates the position of the rack shaft. In the group of elements, a series circuit in which the first magnetoresistive element and the second magnetoresistive element are connected in series and a series circuit in which the third magnetoresistive element and the fourth magnetoresistive element are connected in series are connected in parallel to form a bridge circuit. The potential of a first terminal connected between the first magnetoresistive element and the second magnetoresistive element and the potential of a second terminal connected between the third magnetoresistive element and the fourth magnetoresistive element are input to the arithmetic unit. A plurality of grooves extending in a direction inclined with respect to the axial direction of the rack shaft are formed on the opposed surface of the rack shaft facing the group of elements.

[0004] In the detection unit configured as described above, when the rack shaft moves axially due to the rotation of a pinion shaft meshing with the rack shaft and the relative positions of the first magnetoresistive element to the fourth magnetoresistive element and the plurality of grooves change, the balance of the resistances of the first magnetoresistive element to the fourth magnetoresistive element changes, and the potentials of the first terminal and the second terminal change. The arithmetic unit calculates the position of the rack shaft based on the change in the potential.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: International Publication No. 2021 / 210125 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] In the detection unit described in Patent Document 1, when the rack shaft is inclined in the vehicle width direction, for example, due to vibrations accompanying the running of the vehicle, the intervals between the first magnetoresistive element to the fourth magnetoresistive element and the rack shaft change, and an error occurs in the detected position of the rack shaft.

[0010] Therefore, an object of the present invention is to provide a position detection device that can accurately detect the position of a shaft that moves axially forward and backward.

[0011] Means for Solving the Problems

[0012] For the purpose of solving the above problems, the present invention provides a position detection device for detecting the position of a metal shaft that moves back and forth along the axial direction within a predetermined movement range, comprising: an excitation coil that generates an alternating magnetic field; a detection body that moves integrally with the above-mentioned shaft and links with the magnetic flux of the above-mentioned alternating magnetic field; and a detection coil that has a detection part facing the above-mentioned detection body during the period when the above-mentioned shaft moves from one end of the axial direction to the other end of the axial direction. The induced voltage induced in the above-mentioned detection part by the magnetic flux of the above-mentioned alternating magnetic field changes according to the position of the above-mentioned detection body relative to the above-mentioned detection part. The above-mentioned detection coil has an adjustment part that suppresses the influence of the inclination of the above-mentioned shaft relative to the above-mentioned detection part on the induced voltage induced in the above-mentioned detection part.

[0013] The effects of the invention are as follows.

[0014] According to the position detection device of the present invention, the position of a shaft that moves back and forth along the axial direction can be detected with high precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 FIG. is a schematic diagram of a vehicle equipped with a steer-by-wire steering device having a stroke sensor incorporating the position detection device according to the first embodiment of the present invention.

[0016] Figure 2 is Figure 1 A cross-sectional view of the rack shaft, housing, detection body, and substrate taken along line A-A of

[0017] Figure 3 FIG. is a perspective view showing the rack shaft, housing, detection body, and substrate.

[0018] Figure 4 FIGS. (a) to (d) of are explanatory diagrams showing the wiring patterns of the first wiring layer, second wiring layer, third wiring layer, and fourth wiring layer of the substrate 3.

[0019] Figure 5 FIG. (a) of is an explanatory diagram showing the wiring patterns of the first wiring layer and the third wiring layer overlapping. (b) is an explanatory diagram showing the wiring patterns of the second wiring layer and the fourth wiring layer overlapping.

[0020] Figure 6 FIG. is an explanatory diagram showing the wiring patterns of the first wiring layer, second wiring layer, third wiring layer, and fourth wiring layer overlapping.

[0021] Figure 7 FIG. is a graph showing an example of the relationship between the supply voltage supplied from the power supply unit to the excitation coil and the induced voltages induced in the first detection coil and the second detection coil 6.

[0022] Figure 8It is an explanatory diagram schematically showing the relationship between the peak value of the induced voltage induced by the first detection coil, i.e., the peak voltage, and the position of the detection object.

[0023] Figure 9 It is an explanatory diagram schematically showing the relationship between the peak value of the induced voltage induced by the second detection coil, i.e., the peak voltage, and the position of the detection object.

[0024] Figure 10 In (a), it is an explanatory diagram schematically showing the relationship between the inclination of the rack shaft with respect to the substrate and the influence of the inclination of the rack shaft on the magnetic flux density linked to the first detection coil. (b) is an explanatory diagram schematically showing the relationship between the inclination of the rack shaft with respect to the substrate and the influence of the inclination of the rack shaft on the magnetic flux density linked to the second detection coil.

[0025] Figure 11 It is a graph showing the increment of the detection error of the position of the detection object caused by the inclination of the rack shaft with respect to the substrate in the case where the first detection coil has an adjustment part and in the case where it does not have an adjustment part.

[0026] Figure 12 In (a) to (d), it is an explanatory diagram showing the wiring patterns of the first wiring layer to the fourth wiring layer of the substrate formed with the adjustment part of Modification 1.

[0027] Figure 13 It is an explanatory diagram showing the wiring patterns of the first wiring layer to the fourth wiring layer of the substrate formed with the adjustment part of Modification 1, shown overlapping.

[0028] Figure 14 In (a) to (d), it is an explanatory diagram showing the wiring patterns of the first wiring layer to the fourth wiring layer of the substrate formed with the adjustment part of Modification 2.

[0029] Figure 15 It is an explanatory diagram showing the wiring patterns of the first wiring layer to the fourth wiring layer of the substrate formed with the adjustment part of Modification 2, shown overlapping.

[0030] Symbol Explanation

[0031] 1 - Stroke sensor, 2 - Detection object, 3 - Substrate, 4 - Excitation coil, 5 - First detection coil (detection coil), 51 - Detection part, 510 - Axis of symmetry, 511, 512 - Curve parts, 51A - One side part, 51B - The other side part, 51C - Central part, 52, 53 - Adjustment parts, 6 - Second detection coil. Detailed Description of the Embodiment

[0032] [Embodiment]

[0033] Figure 1It is a schematic diagram of a vehicle equipped with a steer-by-wire type steering device 10 having a stroke sensor 1 that serves as the position detection device of the first embodiment of the present invention.

[0034] As Figure 1 shown, the steering device 10 includes a stroke sensor 1, a steering tie rod 12 connected to the steering wheels 11 (left and right front wheels), a metal rack shaft 13 connected to the steering tie rod 12, a cylindrical housing 14 that houses the rack shaft 13, a worm gear reduction mechanism 15 having a pinion 151 that meshes with the rack teeth 131 of the rack shaft 13, an electric motor 16 that applies an axial moving force to the rack shaft 13 via the worm gear reduction mechanism 15, a steering wheel 17 for the driver to perform a steering operation, a steering angle sensor 18 that detects the steering angle of the steering wheel 17, and a steering control device 19 that controls the electric motor 16 based on the steering angle detected by the steering angle sensor 18.

[0035] Figure 1 In, the housing 14 is shown by a phantom line. The rack shaft 13 is made of a steel material such as carbon steel, for example, and is supported by a pair of rack bushings 132 installed at both end portions of the housing 14. The worm gear reduction mechanism 15 has a worm wheel 152 and a worm 153, and the pinion 151 is fixed to the worm wheel 152. The worm 153 is fixed to the motor shaft 161 of the electric motor 16.

[0036] The electric motor 16 generates torque by the motor current supplied from the steering control device 19, and rotates the worm wheel 152 and the pinion 151 via the worm 153. When the pinion 151 rotates, the rack shaft 13 moves forward and backward in the axial direction within a predetermined movement range in the vehicle width direction, turning the left and right steering wheels 11. The rack shaft 13 can move to the right and left in the vehicle width direction from the neutral position when the steering angle is zero. Figure 1 In, the range R1 in which the rack shaft 13 can move in the vehicle width direction is shown by a double arrow.

[0037] (Structure of the stroke sensor 1)

[0038] The stroke sensor 1 includes a detection body 2 fixed to the rack shaft 13, a substrate 3 disposed opposite to the detection body 2 and arranged in parallel with the rack shaft 13, a power supply unit 7, and an arithmetic unit 8. The substrate 3 is connected to the power supply unit 7 and the arithmetic unit 8 by a connector 91 and a cable 92 installed on the substrate 3. The substrate 3 is fixed in the housing 14 in parallel with the rack shaft 13. The stroke sensor 1 detects the position of the rack shaft 13 relative to the housing 14 based on the position of the detection body 2, and outputs the information on the detected position to the steering control device 19. The steering control device 19 controls the electric motor 16 such that the position of the rack shaft 13 detected by the stroke sensor 1 becomes a position corresponding to the steering angle of the steering wheel 17 detected by the steering angle sensor 18.

[0039] Figure 2 Is Figure 1 A cross-sectional view of the rack shaft 13, the housing 14, the detection body 2, and the substrate 3 at the A-A line thereof. Figure 3 Is a perspective view showing the rack shaft 13, the main body 141 of the housing 14, the detection body 2, and the substrate 3. Figure 3 In, the center axis C of the rack shaft 13 is shown by a single-dot chain line. The rack shaft 13 moves along the center axis C by the moving force imparted by the electric motor 16.

[0040] The rack shaft 13 is a rod-shaped body having a circular cross-section. The housing 14 has a metal main body 141 and a resin cover 142. The cover 142 is fixed to the main body 141 by adhesion, for example. The main body 141 is formed with a storage space 140 for storing the rack shaft 13, and has a U-shaped cross-section. The storage space 140 is open upward in the vertical direction. The diameter D of the rack shaft 13 is, for example, 25 mm.

[0041] A gap of, for example, 1 mm or more is formed between the outer peripheral surface 13a of the rack shaft 13 and the inner surface 140a of the storage space 140. The cover 142 is formed in a flat plate shape and covers the upper part of the storage space 140 in the vertical direction. The main body 141 is a non-magnetic body and is made of, for example, an aluminum alloy formed by die casting. In addition, as the material of the cover 142, it is not necessarily limited to resin, but it is preferably a non-magnetic and non-conductive material.

[0042] The detection body 2 is fixed to the rack shaft 13 so as to project from the outer peripheral surface 13a of the rack shaft 13 toward the substrate 3 and moves integrally with the rack shaft 13. The fixing of the detection body 2 to the rack shaft 13 can be performed by fixing methods such as bonding and welding, for example. The detection body 2 is made of a material having a higher magnetic permeability than that of the rack shaft 13 or a material having a higher conductivity than that of the rack shaft 13. When a material having a higher magnetic permeability than that of the rack shaft 13 is used as the material of the detection body 2, it is preferably a magnetic material such as ferrite having a higher resistance and difficult to generate eddy currents. And, when a material having a higher conductivity than that of the rack shaft 13 is used for the detection body 2, as the material thereof, for example, a metal mainly composed of aluminum or copper can be used.

[0043] In addition, in the present embodiment, since the detection body 2 projects from the outer peripheral surface 13a of the rack shaft 13 toward the substrate 3, even if a material having the same magnetic permeability as that of the rack shaft 13 or a material having the same conductivity as that of the rack shaft 13 is used as the material of the detection body 2, the following functions and effects can be obtained. Among them, in order to improve the detection accuracy of the position, it is preferably to use a high magnetic permeability material having a higher magnetic permeability than that of the material of the rack shaft 13 or a high conductivity material having a higher conductivity than that of the material of the rack shaft 13 as the material of the detection body 2.

[0044] The opposed surface 2a of the detection body 2 opposed to the substrate 3 is formed in a planar shape and faces the front (positive) surface 3a of the substrate 3 in parallel via the air gap G. The back surface 3b of the substrate 3 is fixed to the cover body 142 with an adhesive 143. The shape of the opposed surface 2a of the detection body 2 as viewed from the substrate 3 side is rectangular. The width W of the air gap G is, for example, 1 mm. The minimum thickness T of the detection body 2 in the direction perpendicular to the opposed surface 2a is, for example, 3 mm. In addition, in the present embodiment, the rack shaft 13 is formed to have a circular cross section, but the cross-sectional shape of the rack shaft 13 is not limited to a circular shape, and may be, for example, a D-shaped cross section with a part formed in a straight line shape, or a polygon.

[0045] The substrate 3 is a four-layer substrate having a first wiring layer 31, a second wiring layer 32, a third wiring layer 33, and a fourth wiring layer 34 in this order from the surface 3a side. The first wiring layer 31 and the fourth wiring layer 34 correspond to the outer layers of the substrate 3, and the second wiring layer 32 and the third wiring layer 33 correspond to the inner layers of the substrate 3. Base materials 30 made of a dielectric such as FR4 (a material obtained by impregnating glass fiber with epoxy resin and performing a thermal curing treatment) are disposed between the first wiring layer 31 and the second wiring layer 32, between the second wiring layer 32 and the third wiring layer 33, and between the third wiring layer 33 and the fourth wiring layer 34. The first wiring layer 31 and the fourth wiring layer 34 are covered with an antireflection film 300 having electrical insulation properties. Wiring patterns are formed on the first wiring layer 31, the second wiring layer 32, the third wiring layer 33, and the fourth wiring layer 34, respectively, and the wiring patterns of the respective layers are connected at a plurality of positions on the substrate 3 by vias 35. The substrate 3 has a flat rectangular parallelepiped shape with the axial direction of the rack shaft 13 as the long side direction.

[0046] (Structure of the substrate 3)

[0047] Next, with reference to Figures 4 to 6 , the structure of the wiring in the substrate 3 will be described in detail. Figure 4 The (a) to (d) of are explanatory views showing the wiring patterns of the first wiring layer 31, the second wiring layer 32, the third wiring layer 33, and the fourth wiring layer 34 as viewed from the surface 3a side. Figure 5 The (a) of is an explanatory view showing the wiring pattern of the first wiring layer 31 shown in the (a) of and the wiring pattern of the third wiring layer 33 shown in the (c) of overlapped. Figure 4 The (a) of is an explanatory view showing the wiring pattern of the first wiring layer 31 shown in the (a) of and the wiring pattern of the third wiring layer 33 shown in the (c) of overlapped. Figure 4 The (c) of overlapped. Figure 5 The (b) of is an explanatory view showing the wiring pattern of the second wiring layer 32 shown in the (b) of and the wiring pattern of the fourth wiring layer 34 shown in the (d) of overlapped. Figure 4 The (b) of is an explanatory view showing the wiring pattern of the second wiring layer 32 shown in the (b) of and the wiring pattern of the fourth wiring layer 34 shown in the (d) of overlapped. Figure 4 The (d) of overlapped. Figure 6 is an explanatory view showing the overlap of Figure 4Explanatory diagram of the wiring patterns of the first wiring layer 31, the second wiring layer 32, the third wiring layer 33, and the fourth wiring layer 34 shown in (a) to (d) thereof. Figure 5 in (a), (b), and Figure 6 In [it], the wiring patterns of the third wiring layer 33 and the fourth wiring layer 34 are shown in gray. In addition, Figures 4 to 6 The wiring patterns of the respective layers shown are merely examples, and as long as the substrate 3 is formed in a manner to obtain the effects of the present invention, various wiring patterns can be adopted.

[0048] On the substrate 3, an exciting coil 4 that generates an alternating magnetic field, a first detection coil 5 that links with the magnetic flux of the alternating magnetic field generated by the exciting coil 4, and a second detection coil 6 are formed through the wiring pattern. The exciting coil 4 is formed across the first wiring layer 31 and the third wiring layer 33. The first detection coil 5 is formed across the first wiring layer 31 and the third wiring layer 33, and the second detection coil 6 is formed across the second wiring layer 32 and the fourth wiring layer 34. The first detection coil 5 corresponds to the "detection coil" of the present invention recited in the claims.

[0049] The exciting coil 4, the first detection coil 5, and the second detection coil 6 extend in the long side direction of the substrate 3 along the axial direction of the rack shaft 13. At one end portion in the long side direction of the substrate 3, an input / output portion 36 having first via pads 361 to sixth via pads 366 through which a plurality of connector pins of the connector 91 shown are inserted is formed. Hereinafter, the side on which the input / output portion 36 is formed on both sides in the long side direction of the substrate 3 is referred to as the long side direction one side, and the opposite side thereof is referred to as the long side direction the other side. Figure 1

[0050] (Structure of the exciting coil 4)

[0051] The exciting coil 4 has a pair of long side portions 41, 42 that extend in the long side direction of the substrate 3, a pair of short side portions 43, 44 between the pair of long side portions 41, 42, and a connection line portion 45 between the short side portion 43 on the long side direction one side of the pair of short side portions 43, 44 and the input / output portion 36. The long side portions 41, 42 of the exciting coil 4 are formed by conductor lines 411, 421 formed in the first wiring layer 31 and conductor lines 412, 422 formed in the third wiring layer 33. The short side portions 43, 44 of the exciting coil 4 are formed by conductor lines 431, 441 formed in the first wiring layer 31 and conductor lines 432, 442 formed in the third wiring layer 33. The connection line portion 45 is formed by a conductor line 451 formed in the first wiring layer 31 and a conductor line 452 formed in the third wiring layer 33. The conductor line 451 of the connection line portion 45 is connected to the first via pad 361 of the input / output portion 36, and the conductor line 452 is connected to the sixth via pad 366.

[0052] The first detection coil 5 and the second detection coil 6 are formed inside a pair of long side portions 41, 42 and a pair of short side portions 43, 44 of the exciting coil 4 having a rectangular parallelepiped shape. An alternating current is supplied from the power supply unit 7 to the exciting coil 4 via the connector 91 and the cable 92. The exciting coil 4 generates an alternating magnetic field having a frequency corresponding to the frequency of the alternating current. The magnetic flux of the alternating magnetic field generated by the exciting coil 4 links with the first detection coil 5 and the second detection coil 6, generating an induced voltage corresponding to the frequency of the alternating magnetic field.

[0053] The magnetic flux of the alternating magnetic field generated by the exciting coil 4 also links with the detection object 2. The magnetic flux linking with the detection object 2 affects the intensity distribution of the magnetic flux linking with the first detection coil 5 and the second detection coil 6, and the magnitudes of the induced voltages generated in the first detection coil 5 and the second detection coil 6 by the alternating magnetic field generated by the exciting coil 4 change according to the position of the detection object 2. Figure 6 In the figure, the position of the detection object 2 when the rack shaft 13 is at the mobile end on one axial side is shown by a dashed line, and the position of the detection object 2 when the rack shaft 13 is at the mobile end on the other axial side is shown by a double-dot chain line.

[0054] During the period when the rack shaft 13 moves from the mobile end on one axial side to the mobile end on the other axial side, the phases of the magnitudes of the induced voltages respectively induced in the first detection coil 5 and the second detection coil 6 that change according to the position of the detection object 2 are different from each other. In the present embodiment, during the period when the rack shaft 13 moves from the mobile end on one axial side to the mobile end on the other axial side, the phases of the changes in the magnitudes of the induced voltages induced in the first detection coil 5 and the second detection coil 6 differ by 90°.

[0055] (Structure of the first detection coil 5)

[0056] The first detection coil 5 has a detection portion 51 facing the detection object 2 during the period when the rack shaft 13 moves from the mobile end on one axial side to the mobile end on the other axial side, two adjustment portions 52, 53 provided on both sides of the detection portion 51 in the long side direction of the substrate 3, and a connection line portion 54 for connecting to the input / output portion 36. The adjustment portions 52, 53 suppress the influence of the inclination of the rack shaft 13 with respect to the substrate 3 and the detection portion 51 on the induced voltage induced in the detection portion 51. The functions and effects of the adjustment portions 52, 53 will be described below.

[0057] The detection portion 51 has a shape formed by combining a pair of curved portions 511, 512. Figures 4 to 6In the example shown, the curved portion 511 is formed on the first wiring layer 31, and the curved portion 512 is formed on the third wiring layer 33. The curved portions 511 and 512 are sinusoidal conductor lines that are symmetric in the width direction of the substrate 3 with the symmetric axis 510 extending along the long side direction of the substrate 3 and the detection unit 51 interposed therebetween. More specifically, the shape of the curved portion 511 in the first wiring layer 31 as observed from the normal direction of the substrate 3 is a sine wave shape from -180° to 180° when the symmetric axis 510 is regarded as the phase axis as shown in Figure 4 (a) thereof, and the shape of the curved portion 512 in the third wiring layer 33 as observed from the normal direction of the substrate 3 is a sine wave shape from 0° to 360° when the symmetric axis 510 is regarded as the phase axis as shown in Figure 4 (c) thereof.

[0058] As shown in Figure 5 (a) thereof, one curved portion 511 and the other curved portion 512 constituting the detection unit 51 cross each other at the central portion 51C in the long side direction of the detection unit 51 without contacting (short-circuiting) each other. Further, the curved portions 511 and 512 approach each other toward the symmetric axis 510 at both end portions in the long side direction of the detection unit 51, and the interval expands between the both end portions and the central portion 51C.

[0059] The shapes of the adjustment units 52 and 53 as observed from the normal direction of the substrate 3 are rectangular. The adjustment unit 52 provided on one side in the long side direction of the detection unit 51 is composed of a conductor line 521 continuously formed on the first wiring layer 31 from one end portion in the long side direction of the curved portion 511 constituting the detection unit 5, and a conductor line 522 continuously formed on the third wiring layer 33 from one end portion in the long side direction of the curved portion 512 constituting the detection unit 51. The adjustment unit 53 provided on the other side in the long side direction of the detection unit 51 is composed of a conductor line 531 continuously formed on the first wiring layer 31 from the other end portion in the long side direction of the curved portion 511 constituting the detection unit 51, and a conductor line 532 continuously formed on the third wiring layer 33 from the other end portion in the long side direction of the curved portion 512 constituting the detection unit 51. The conductor line 531 and the conductor line 532 are connected by a via hole 35 at the other end portion in the long side direction of the adjustment unit 53.

[0060] The connection line portion 54 connects the adjustment unit 52 on one side in the long side direction to the input / output unit 36. In the present embodiment, the connection line portion 54 is composed of a conductor line 541 that connects one end portion in the long side direction of the conductor line 521 of the adjustment unit 52 to the fifth via hole pad 365, and a conductor line 542 that connects one end portion in the long side direction of the conductor line 522 of the adjustment unit 52 to the fourth via hole pad 364. The conductor line 541 is formed on the first wiring layer 31 along the symmetric axis 510. The conductor line 542 is formed on the third wiring layer 33 along the symmetric axis 510.

[0061] When the short side direction perpendicular to the long side direction of the substrate 3 is taken as the width direction, the portion of the curved portion 511 constituting the detection portion 51 on the long side direction side with respect to the central portion 51C is provided on the width direction side (lower side of the drawing) of the symmetry axis 510, and the portion on the other side of the long side direction with respect to the central portion 51C is provided on the other width direction side (upper side of the drawing) of the symmetry axis 510. The conductor line 521 of the adjustment portion 52 formed continuously with the end portion on the long side direction side of the curved portion 511 is provided on the other width direction side (upper side of the drawing) of the symmetry axis 510, and the conductor line 531 of the adjustment portion 53 formed continuously with the end portion on the other long side direction side of the curved portion 511 is provided on the width direction side (lower side of the drawing) of the symmetry axis 510.

[0062] Moreover, the portion of the curved portion 512 that constitutes the detection portion 51 together with the curved portion 511 on the long side direction side with respect to the central portion 51C is provided on the other width direction side (upper side of the drawing) of the symmetry axis 510, and the portion on the other side of the long side direction with respect to the central portion 51C is provided on the width direction side (lower side of the drawing) of the symmetry axis 510. The conductor line 522 of the adjustment portion 52 formed continuously with the end portion on the long side direction side of the curved portion 512 is provided on the width direction side (lower side of the drawing) of the symmetry axis 510, and the conductor line 532 of the adjustment portion 53 formed continuously with the end portion on the other long side direction side of the curved portion 512 is provided on the other width direction side (upper side of the drawing) of the symmetry axis 510.

[0063] According to the structure of the first detection coil 5, the direction of the induced voltage generated in the portion of the detection portion 51 on the long side direction side with respect to the central portion 51C, that is, the one side portion 51A, is opposite to the direction of the induced voltage generated in the adjustment portion 52 provided at a position on the long side direction side with respect to the detection portion 51. Also, the direction of the induced voltage generated in the portion of the detection portion 51 on the other side of the long side direction with respect to the central portion 51C, that is, the other side portion 51B, is opposite to the direction of the induced voltage generated in the adjustment portion 53 provided at a position on the other long side direction side with respect to the detection portion 51.

[0064] Figure 5 In (a) of, when the intensity of the magnetic field in the direction from the front side of the drawing toward the back side of the drawing gradually becomes stronger, the directions of the currents that can be generated in the curved portions 511, 512 of the detection portion 51, the conductor lines 521, 522 of the adjustment portion 52, and the conductor lines 531, 532 of the adjustment portion 53 due to the change in the intensity of the magnetic field are respectively indicated by arrow A 51 、arrow A 52 、arrow A 53Shown. Assume that when the detection body 2 is not mounted on the rack shaft 13 and the symmetry axis 510 is parallel to the central axis C of the rack shaft 13, the induced voltage generated in one side portion 51A and the induced voltage generated in the other side portion 51B are balanced and canceled out, and the induced voltage generated in the adjustment portion 52 on one side in the long side direction and the induced voltage generated in the adjustment portion 53 on the other side in the long side direction are balanced and canceled out. Therefore, no current flows in the first detection coil 5.

[0065] Moreover, in the present embodiment, the maximum width W of the detection portion 51 in the width direction of the substrate 3 51 is equal to the maximum widths W of the adjustment portions 52 and 53 52 , W 53 . More specifically, the maximum widths W of the adjustment portions 52 and 53 52 , W 53 are 95% or more and 105% or less of the maximum width W of the detection portion 51 51 . This structure effectively uses the spaces of the substrate 3 on one side and the other side in the long side direction of the detection portion 51 as the spaces of the adjustment portions 52 and 53, which helps to miniaturize the substrate 3. An idle space is provided between the pair of short side portions 43 and 44 of the exciting coil 4 and the adjustment portions 52 and 53 to suppress the influence of the magnetic field generated by the current flowing in the short side portions 43 and 44 on the induced voltage generated in the adjustment portions 52 and 53.

[0066] (Structure of the second detection coil 6)

[0067] The second detection coil 6 has a detection portion 61 that faces the detection body 2 during the movement of the rack shaft 13 from the mobile end on one axial side to the mobile end on the other axial side, and a connection line portion 62 for connecting to the input / output portion 36. The position and length of the detection portion 61 of the second detection coil 6 in the long side direction of the substrate 3 are the same as the position and length of the detection portion 51 of the first detection coil 5, and the detection portion 61 of the second detection coil 6 overlaps with the detection portion 51 of the first detection coil 5 in the thickness direction of the substrate 3.

[0068] The detection portion 61 is composed of the following parts: a pair of curved portions 611 and 612 that are symmetric in the width direction of the substrate 3 with the symmetry axis 610 extending in the long side direction of the substrate 3 interposed therebetween; straight portions 613 and 614 that extend from the respective axial-side ends of the curved portions 611 and 612 toward the symmetry axis 610 in the width direction of the substrate 3; and straight portions 615 and 616 that extend from the respective axial-opposite ends of the curved portions 611 and 612 toward the symmetry axis 610 in the width direction of the substrate 3. The curved portion 611 and the straight portions 613 and 615 are formed in the second wiring layer 32. The curved portion 612 and the straight portions 614 and 616 are formed in the fourth wiring layer 34.

[0069] A pair of curved portions 611 and 612 are sinusoidal conductor lines that are symmetric in the width direction of the substrate 3 with respect to a symmetry axis 610 extending along the long side direction of the substrate 3 and the detection unit 61. More specifically, the shape of the curved portion 611 in the second wiring layer 32 as observed from the normal direction of the substrate 3 is a cosine wave shape from 0° to 360° when the symmetry axis 610 is regarded as the phase axis as shown in (b) of Figure 4 , and the shape of the curved portion 612 in the fourth wiring layer 34 as observed from the normal direction of the substrate 3 is a cosine wave shape from -180° to 180° when the symmetry axis 610 is regarded as the phase axis as shown in (d) of Figure 4 . The pair of curved portions 611 and 612 cross at two crossing portions 601 and 602 in the long side direction in the detection unit 61. The straight portion 615 of the second wiring layer 32 extending from the end on the other axial side of the pair of curved portions 611 and 612 is connected to the straight portion 616 of the fourth wiring layer 34 by a via 35.

[0070] The connection line portion 62 connects the ends on one axial side of the pair of curved portions 611 and 612 to the input / output portion 36. In the present embodiment, the connection line portion 62 is composed of a conductor line 621 that connects the end on the long side direction side of the curved portion 611 to the second via pad 362, and a conductor line 622 that connects the end on the long side direction side of the curved portion 612 to the third via pad 363. The conductor line 621 is formed in the second wiring layer 32 along the symmetry axis 610. The conductor line 622 is mainly formed in the fourth wiring layer 34 along the symmetry axis 610, but the portion that crosses the short side portion 43 of the excitation coil 4 is formed in the third wiring layer 33 via a plurality of vias 35.

[0071] The first detection coil 5 and the second detection coil 6 output an output signal, which is a voltage induced by the alternating magnetic field generated by the excitation coil 4, to the arithmetic unit 8 via the connector 91 and the cable 92. The arithmetic unit 8 calculates the position of the detection object 2 based on the output signal and sends the calculation result to the steering control device 19. During the period when the rack shaft 13 moves from the mobile end on one axial side to the mobile end on the other axial side, the peak value of the voltage induced by the first detection coil 5 and the second detection coil 6 varies within a range of less than one cycle. Thus, the stroke sensor 1 can detect the absolute position of the rack shaft 13 over the entire range R1 in which the rack shaft 13 can move axially.

[0072] (Operation of the stroke sensor 1)

[0073] Next, with reference to Figures 7 to 9 , the operation of the stroke sensor 1 for detecting the position of the detection object 2 with respect to the substrate 3 will be described. In the following description, the position of the detection object 2 refers to the center point 20 of the opposed surface 2a in the axial direction (refer to Figure 3The position of (). Moreover, the fact that the first detection coil 5 and the second detection coil 6 overlap with the detection object 2 means that the first detection coil 5 and the second detection coil 6 are arranged along the normal direction of the substrate 3 with respect to the detection object 2.

[0074] Figure 7 is a graph showing an example of the relationship between the supply voltage V0 supplied from the power supply unit 7 to the excitation coil 4, the induced voltage V1 induced in the first detection coil 5, and the induced voltage V2 induced in the second detection coil 6 when the detection object 2 overlaps with the detection units 51 and 61 of the first detection coil 5 and the second detection coil 6. Figure 7 The horizontal axis of the graph is the time axis, and the left and right vertical axes show the supply voltage V0 and the induced voltages V1 and V2.

[0075] In Figure 7 the example shown, although the supply voltage V0 is in phase with the induced voltages V1 and V2, each time the detection object 2 passes through the central portion 51C of the detection unit 51 of the first detection coil 5, the induced voltage V1 induced in the first detection coil 5 switches between in-phase and out-of-phase. Also, each time the detection object 2 passes through the crossing portions 601 and 602 where a pair of curved portions 611 and 612 cross, the induced voltage V2 induced in the second detection coil 6 switches between in-phase and out-of-phase. As the supply voltage V0, an alternating voltage of high frequency, for example, around 1 MHz to 1 GHz, is supplied to the excitation coil 4.

[0076] Figure 8 is an explanatory diagram schematically showing the relationship between the peak value, i.e., the peak voltage Vs, of the induced voltage V1 induced in the first detection coil 5 and the position of the detection object 2. Figure 9 is an explanatory diagram schematically showing the relationship between the peak value, i.e., the peak voltage Vc, of the induced voltage V2 induced in the second detection coil 6 and the position of the detection object 2. In Figure 8 and Figure 9 in the graphs of the peak voltages Vs and Vc shown, the horizontal axis shows the position of the detection object 2.

[0077] The stroke sensor 1 can detect the absolute position of the detection object 2 within the range where the entire axial length of the detection object 2 in the axial direction of the rack shaft 13 overlaps with the detection units 51 and 61 of the first detection coil 5 and the second detection coil 6. In Figure 8 and Figure 9 in the graphs shown, the horizontal axis coordinate of the detection object 2 when the rack shaft 13 is at the mobile end on one side in the axial direction is set as P1, and the horizontal axis coordinate of the detection object 2 when the rack shaft 13 is at the mobile end on the other side in the axial direction is set as P2, and the peak voltages Vs and Vc at each position are shown.

[0078] Moreover, in Figure 8 and Figure 9In the shown curve graph, for the peak voltage Vs of the first detection coil 5, the peak voltage when the induced voltage V1 induced by the first detection coil 5 is in phase with the supply voltage V0 supplied to the excitation coil 4 is set as a positive value, and the peak voltage when they are out of phase is set as a negative value. Similarly, for the peak voltage Vc of the second detection coil 6, the peak voltage when the induced voltage V2 induced by the second detection coil 6 is in phase with the supply voltage V0 supplied to the excitation coil 4 is set as a positive value, and the peak voltage when they are out of phase is set as a negative value.

[0079] Here, when ωx is defined as in Equation [1], Figure 8 、 Figure 9 the coordinate value of the horizontal axis coordinate of the detection object 2 in the shown curve graph is set as Xp, and the peak voltages Vs and Vc are obtained respectively using Equation [2] and Equation [3]. In Equation [1], L1 is the length in the long side direction of the detection parts 51 and 61 of the first detection coil 5 and the second detection coil 6. In Equation [2] and Equation [3], A is a predetermined constant, and L2 is the axial length of the detection object 2.

[0080] Equation 1

[0081]

[0082] Equation 2

[0083]

[0084] Equation 3

[0085]

[0086] According to Equation [2] and Equation [3], Equation [4] is used to obtain Figure 8 and Figure 9 the coordinate value Xp of the detection object 2 in the shown curve graph. That is, the arithmetic unit 8 can calculate the position of the detection object 2 based on the peak voltages Vs and Vc through arithmetic operations.

[0087] Equation 4

[0088]

[0089] (Functions and effects of the adjustment parts 52 and 53 of the first detection coil 5)

[0090] For example, if the rack shaft 13 is inclined with respect to the substrate 3 due to the vibration during the running of the vehicle, and the intervals between the respective parts of the substrate 3 and the rack shaft 13 change, then the degree of influence of the rack shaft 13 on the intensity distribution of the magnetic flux inside the excitation coil 4 varies according to the position of the substrate 3 in the long side direction. In the present embodiment, the adjustment parts 52 and 53 of the first detection coil 5 suppress the influence of the inclination of the rack shaft 13 on the detection accuracy of the position of the detection body 2. Next, the functions and effects of the adjustment parts 52 and 53 will be described by comparison with a comparative example.

[0091] Figure 10 Fig. (a) is an explanatory diagram schematically showing the relationship between the inclination of the rack shaft 13 with respect to the substrate 3 and the influence of the inclination of the rack shaft 13 on the magnetic flux density linked to the first detection coil 5. Figure 10 Fig. (b) is an explanatory diagram schematically showing the relationship between the inclination of the rack shaft 13 with respect to the substrate 3 and the influence of the inclination of the rack shaft 13 on the magnetic flux density linked to the second detection coil 6. Figure 10 In Figs. (a) and (b), the bisecting line BL of the detection parts 51 and 61 of the first detection coil 5 and the second detection coil 6 is shown by a two-dot chain line, and a state is shown in which the rack shaft 13 is inclined in the up-and-down direction of the drawing with the point indicated by the target mark TM on the bisecting line BL as the center. The rack shaft 13 is inclined such that the part closer to the substrate 3 is on the left side of the target mark TM in the drawing and the part farther from the substrate 3 is on the right side of the target mark TM in the drawing. In addition, Figure 10 in Figs. (a) and (b), the inclination of the rack shaft 13 is exaggeratedly shown.

[0092] Eddy currents flow in the rack shaft 13 due to the magnetic flux linkage of the alternating magnetic field generated by the excitation coil 4. The eddy currents act to weaken the magnetic flux linked to the first detection coil 5 and the second detection coil 6. The closer the part of the rack shaft 13 is to the substrate 3, the greater the influence of this action. Figure 10 In Figs. (a) and (b), the regions inside the first detection coil 5 and the second detection coil 6 where the influence becomes larger due to the inclination of the rack shaft 13 are shown in dark gray, and the regions inside the first detection coil 5 and the second detection coil 6 where the influence becomes smaller due to the inclination of the rack shaft 13 are shown in light gray.

[0093] As Figure 10As shown in (a), in one side portion 51A of the detection portion 51 and the adjustment portion 52 of the first detection coil 5, due to the inclination of the rack shaft 13 as shown in the figure, the influence of the eddy current generated in the rack shaft 13 becomes larger and the magnetic flux density becomes lower. Regarding this influence, the adjustment portion 52 located at a position farther from the bisector BL is larger than the one side portion 51A of the detection portion 51. Also, in the other side portion 51B of the detection portion 51 and the adjustment portion 53 of the first detection coil 5, due to the inclination of the rack shaft 13 as shown in the figure, the influence of the eddy current generated in the rack shaft 13 becomes smaller and the magnetic flux density becomes higher. Regarding this influence, the adjustment portion 53 located at a position farther from the bisector BL is larger than the other side portion 51B of the detection portion 51.

[0094] However, the sum of the change amount of the induced voltage V1 of the first detection coil 5 due to the decrease in the magnetic flux density in the one side portion 51A of the detection portion 51 and the change amount of the induced voltage V1 of the first detection coil 5 due to the increase in the magnetic flux density in the other side portion 51B of the detection portion 51 cancels out the sum of the change amount of the induced voltage V1 of the first detection coil 5 due to the decrease in the magnetic flux density in the adjustment portion 52 and the change amount of the induced voltage V1 of the first detection coil 5 due to the increase in the magnetic flux density in the adjustment portion 53. Thereby, the detection accuracy of the position of the detection object 2, that is, the detection accuracy of the position of the rack shaft 13, can be improved.

[0095] Also, regarding the influence of the change in the magnetic flux density caused by the inclination of the rack shaft 13 with respect to the substrate 3, it becomes larger in the adjustment portions 52 and 53 compared to the one side portion 51A and the other side portion 51B of the detection portion 51. Therefore, when the maximum width W of the detection portion 51 in the width direction of the substrate 3 51 is equal to the maximum widths W of the adjustment portions 52 and 53 52 、W 53 even if the length L of the adjustment portion 52 in the long side direction of the substrate 3 52 is shorter than the length L of the one side portion 51A of the first detection coil 5 51A and the length L of the adjustment portion 53 in the long side direction of the substrate 3 53 is shorter than the length L of the other side portion 51B of the first detection coil 5 51B it is possible to cancel out the change amount of the induced voltage V1 of the first detection coil 5 caused by the change in the magnetic flux density in the one side portion 51A and the other side portion 51B of the detection portion 51 due to the inclination of the rack shaft 13 and the change amount of the induced voltage V1 of the first detection coil 5 caused by the change in the magnetic flux density in the adjustment portions 52 and 53.

[0096] According to the geometric analysis considering the change in the magnetic flux density caused by the inclination of the rack shaft 13 with respect to the substrate 3, the maximum width W of the detection portion 51 in the width direction of the substrate 351 When the maximum widths W of the adjustment parts 52 and 53 52 and W 53 are the same, when the lengths L of the adjustment parts 52 and 53 in the long side direction of the substrate 3 52 and L 53 are 14% of the length L1 (L1 = L 51A + L 51B ) in the long side direction of the detection parts 51 and 61 of the first detection coil 5, the change amount of the induced voltage V1 of the first detection coil 5 caused by the increase and decrease of the magnetic flux density in one side part 51A and the other side part 51B of the detection part 51 becomes equal to the change amount of the induced voltage V1 of the first detection coil 5 caused by the increase and decrease of the magnetic flux density in the adjustment parts 52 and 53. Even if the rack shaft 13 is inclined with respect to the substrate 3, the induced voltage V1 will not change due to this.

[0097] In addition, regarding the second detection coil 6, in terms of its structure, even if the rack shaft 13 is inclined with respect to the substrate 3, the change of the induced voltage V2 can be suppressed. This is because, as shown in (b) of Figure 10 , when the area inside the detection part 61 of the second detection coil 6 is divided into a first partition 61A, a second partition 61B, a third partition 61C, and a fourth partition 61D in the long side direction, the influence of the change of the magnetic flux density due to the inclination of the rack shaft 13 on the induced voltage V2 cancels out in the second partition 61B and the third partition 61C, and also cancels out in the first partition 61A and the fourth partition 61D. Here, the first partition 61A is the area on the long side direction side closer to the crossing part 601. The second partition 61B is the area between the central part 600 in the long side direction of the detection part 61 and the crossing part 601. The third partition 61C is the area between the central part 60, and the fourth partition 61D is the area on the other side of the long side direction closer to the crossing part 602.

[0098] Figure 11It is a graph showing the increment of the detection error of the position of the detection object 2 caused by the inclination of the rack shaft 13 relative to the substrate 3 in the case where the first detection coil 5 has the adjustment parts 52 and 53 and in the case where it does not have the adjustment parts 52 and 53. The horizontal axis of this graph shows the position of the detection object 2 on the - side (axial one side) and the + side (axial other side) when the position of the detection object 2 when the rack shaft 13 is in the neutral position is set to 0 mm. The vertical axis represents the increment of the detection error of the position of the detection object 2 caused by the inclination of the rack shaft 13 by 0.5° in %FS (FS means full scale). The black circles (●) in the graph are the evaluation results in the case where the first detection coil 5 does not have the adjustment parts 52 and 53. The open circles (○) in the graph are the evaluation results in the case where the first detection coil 5 has the adjustment parts 52 and 53. The maximum widths W 52 , W 53 of the adjustment parts 52 and 53 to be evaluated are the same as the maximum width W 51 of the detection part 51, and the lengths L 52 , L 53 in the long side direction are 14% of the length L1 in the long side direction of the detection parts 51 and 61 of the first detection coil 5.

[0099] As Figure 11 shown, since the first detection coil 5 has the adjustment parts 52 and 53, the error of the position of the detected detection object 2 is greatly reduced.

[0100] [Modification Example 1 of the Adjustment Parts 52 and 53]

[0101] Next, with reference to Figure 12 and Figure 13 a description will be given of Modification Example 1 of the adjustment parts 52 and 53. Figure 12 (a) to (d) of show explanatory diagrams of the wiring patterns of the first wiring layer 31, the second wiring layer 32, the third wiring layer 33, and the fourth wiring layer 34 of the substrate 3 on which the adjustment parts 52 and 53 of Modification Example 1 are formed. Figure 13 is an explanatory diagram showing the wiring patterns of the first wiring layer 31, the second wiring layer 32, the third wiring layer 33, and the fourth wiring layer 34 shown in (a) to (d) of Figure 12 overlapped.

[0102] In the above-described embodiment, the case where the adjustment parts 52 and 53 are each one turn has been described, but in Modification Example 1, the adjustment parts 52 and 53 are each three turns. More specifically, the conductor lines 521 and 522 constituting the adjustment part 52 and the conductor lines 531 and 532 constituting the adjustment part 53 are each 1.5 turns, constituting the adjustment parts 52 and 53 of three turns.

[0103] According to this modification 1, in addition to the effects of the above-described embodiment, the lengths of the adjustment portions 52 and 53 in the longitudinal direction of the substrate 3 can be shortened compared to the above-described embodiment, and the substrate 3 can be made compact.

[0104] [Modification 2 of Adjusters 52 and 53]

[0105] Next, refer to Figure 14 and Figure 15 A second modification of the adjustment units 52 and 53 will be described. Figure 14 (a) to (d) are explanatory diagrams showing wiring patterns of the first wiring layer 31 , the second wiring layer 32 , the third wiring layer 33 , and the fourth wiring layer 34 of the substrate 3 on which the adjustment portions 52 and 53 according to the second modification are formed. Figure 15 is shown overlappingly Figure 14 1 and 2 are explanatory diagrams of wiring patterns of the first wiring layer 31 , the second wiring layer 32 , the third wiring layer 33 , and the fourth wiring layer 34 shown in (a) to (d).

[0106] In the above-mentioned embodiment, reference is made to Figure 4 and Figure 5 In the structural example of the adjustment parts 52 and 53 described above, the conductor line 521 of the adjustment part 52 formed continuously with the end part on one side of the long side direction of the curved part 511 constituting the detection part 51, and the conductor line 532 of the adjustment part 53 formed continuously with the end part on the other side of the long side direction of the curved part 512 constituting the detection part 51 are formed on the other side of the width direction of the symmetry axis 510 (the upper side of the drawing), and the conductor line 531 of the adjustment part 53 formed continuously with the end part on the other side of the long side direction of the curved part 511 constituting the detection part 51, and the conductor line 522 of the adjustment part 52 formed continuously with the end part on one side of the long side direction of the curved part 512 constituting the detection part 51 are formed on one side of the width direction of the symmetry axis 510 (the lower side of the drawing) are described. However, in the second modification, the configuration of the conductor lines 521, 522, 531, 532 of the adjustment parts 52 and 53 in the width direction of the substrate 3 is opposite to the above. Furthermore, the winding manner of the conductor wires 521 , 522 , 531 , and 532 when viewed from the curved portions 511 and 512 is opposite to that of the above-described embodiment.

[0107] According to this modification 2, the same effects as those of the above-described embodiment can be obtained by performing the same operations.

[0108] (Summary of implementation methods)

[0109] Next, the technical ideas grasped from the above-described embodiments will be described with reference to the symbols in the embodiments. However, the symbols in the following description do not limit the constituent elements in the claims to the components specifically shown in the embodiments.

[0110] [1] A position detection device 1 for detecting the position of a metal rack shaft 13 that moves axially back and forth within a predetermined movement range, comprising: an exciting coil 4 that generates an alternating magnetic field; a detection body 2 that moves integrally with the shaft 13 and links with the magnetic flux of the alternating magnetic field; and a detection coil 5 that has a detection portion 51 facing the detection body 2 during the movement of the shaft 13 from one axial end to the other axial end. The induced voltage induced by the magnetic flux of the alternating magnetic field in the detection portion 51 changes according to the position of the detection body 2 relative to the detection portion 51. The detection coil 5 has adjustment portions 52 and 53 that suppress the influence of the inclination of the shaft 13 relative to the detection portion 51 on the induced voltage induced in the detection portion 51.

[0111] [2] According to the position detection device 1 described in the above [1], the detection portion 51 extends in the long side direction along the axial direction of the shaft 13, and the adjustment portions 52 and 53 are provided on both sides of the detection portion 51 in the long side direction.

[0112] [3] According to the position detection device 1 described in the above [2], the detection portion 51 has a shape formed by combining a pair of curved portions 511 and 512 that are symmetric with respect to a symmetry axis extending in the long side direction. The pair of curved portions 511 and 512 intersect at a central portion 51C in the long side direction of the detection portion 51. The direction of the induced voltage generated in a portion 51A of the detection portion 51 on one side of the central portion 51C in the long side direction is opposite to the direction of the induced voltage generated in the adjustment portions 52 and 53 provided on one side of the detection portion 51 in the long side direction. The direction of the induced voltage generated in a portion 51B of the detection portion 51 on the other side of the central portion 51C in the long side direction is opposite to the direction of the induced voltage generated in the adjustment portions 52 and 53 provided on the other side of the detection portion 51 in the long side direction.

[0113] [4] According to the position detection device 1 described in the above [3], the maximum width W of the detection portion 51 in the width direction perpendicular to the long side direction 51 and the maximum width W of the adjustment portions 52 and 53 52 , W 53 are equal.

[0114] [5] According to the position detection device 1 described in the above [1] to [4], the exciting coil 4 and the detection coil 5 are formed on a single substrate 3.

[0115] [6]According to the position detection device 1 described in [5] above, a second detection coil 6 having a shape formed by combining a pair of curved portions 611 and 612 is formed on the substrate 3. During the movement of the shaft 13 from the mobile end on one side in the axial direction to the mobile end on the other side in the axial direction, the phase of the change in the magnitude of the induced voltage induced in the second detection coil 6 differs from the phase of the change in the magnitude of the induced voltage induced in the detection coil 5 by 90°.

[0116] [7]According to the position detection device 1 described in [1] above, the shaft 13 is a rack shaft 13 of the steering device 10 of a vehicle.

[0117] As described above, the embodiments of the present invention have been described, but the above embodiments do not limit the invention of the claims. And it should be noted that the combination of all the features described in the embodiments is not necessarily a solution for solving the problems of the invention. In addition, the present invention can be appropriately modified and implemented within the scope of its gist. For example, it can be implemented as follows.

[0118] And in the above embodiments, the case where the first detection coil 5 and the second detection coil 6 are in a sinusoidal curve shape has been described, but it is not limited thereto. For example, it can also be in a triangular wave shape. And the excitation coil 4, the first detection coil 5, and the second detection coil 6 do not necessarily have to be formed on a single substrate. In addition, in the above embodiments, the case where the detection object of the position of the stroke sensor 1 is the rack shaft of the steering device has been described, but the detection object of the present invention is not limited to the rack shaft and can be applied to the detection of the position of a metal shaft that moves forward and backward along the axial direction.

Claims

1. A position detection device that detects the position of a metal shaft that moves axially back and forth within a predetermined moving range, characterized in that, Comprising: An exciting coil that generates an alternating magnetic field; A detecting body that moves integrally with the above-mentioned shaft and is linked with the magnetic flux of the above-mentioned alternating magnetic field; and A detecting coil that has a detecting portion facing the above-mentioned detecting body during the movement of the above-mentioned shaft from a mobile end on one axial side to a mobile end on the other axial side, The induced voltage induced by the magnetic flux of the above-mentioned alternating magnetic field in the above-mentioned detecting portion varies according to the position of the above-mentioned detecting body relative to the above-mentioned detecting portion, The above-mentioned detecting coil has an adjusting portion that suppresses the influence of the inclination of the above-mentioned shaft relative to the above-mentioned detecting portion on the induced voltage induced in the above-mentioned detecting portion.

2. The position detecting device according to claim 1, wherein The above-mentioned detecting portion extends in the long side direction along the axial direction of the above-mentioned shaft, The above-mentioned adjusting portion is provided on both sides of the above-mentioned detecting portion in the above-mentioned long side direction.

3. The position detecting device according to claim 2, wherein The above-mentioned detecting portion has a shape formed by combining a pair of curved portions that are symmetric with respect to a symmetry axis extending in the above-mentioned long side direction, The above-mentioned pair of curved portions intersect at the central portion of the above-mentioned detecting portion in the above-mentioned long side direction, The direction of the induced voltage generated in the portion of the above-mentioned detecting portion on one side of the above-mentioned central portion in the above-mentioned long side direction is opposite to the direction of the induced voltage generated in the above-mentioned adjusting portion provided on one side of the above-mentioned detecting portion in the above-mentioned long side direction, The direction of the induced voltage generated in the portion of the above-mentioned detecting portion on the other side of the above-mentioned central portion in the above-mentioned long side direction is opposite to the direction of the induced voltage generated in the above-mentioned adjusting portion provided on the other side of the above-mentioned detecting portion in the above-mentioned long side direction.

4. The position detecting device according to claim 3, wherein The maximum width of the above-mentioned detecting portion in the width direction perpendicular to the above-mentioned long side direction is equal to the maximum width of the above-mentioned adjusting portion.

5. The position detecting device according to any one of claims 1 to 4, wherein The above-mentioned exciting coil and the above-mentioned detecting coil are formed on a single substrate.

6. The position detecting device according to claim 5, wherein A second detecting coil having a shape formed by combining a pair of curved portions is formed on the above-mentioned substrate, During the movement of the above-mentioned shaft from the mobile end on one axial side to the mobile end on the other axial side, the phase of the change in the magnitude of the induced voltage induced in the above-mentioned second detecting coil differs by 90° from the phase of the change in the magnitude of the induced voltage induced in the above-mentioned detecting coil.

7. The position detecting device according to claim 1, wherein The above-mentioned shaft is a rack shaft of a steering device of a vehicle.

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