Position detection device and vehicle steering device

Abstract

To provide a position detector with which downsizing is possible, and a steering device for vehicles that includes the position detector.SOLUTION: A stroke sensor 10 for detecting the position of a rack shaft 12 that moves forward and backward in a prescribed movement direction comprises a detection target 2 that is attached to the rack shaft 12, and an excitation coil 31 and a detection coil 32 that extend in the movement direction of the rack shaft 12 and face the detection target 2. A recess 20 that is recessed in a direction to recede from the excitation coil 31 and the detection coil 32 is formed in the detection target 2, and a voltage is induced to the detection coil 32 by a current flowing in the detection target 2 due to a magnetic field generated by the excitation coil 31, with the magnitude of the voltage induced to the detection coil 32 varying depending on the position of the recess 20 relative to the detection coil 32.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a position detection device for detecting the position of a moving member, and a steering device for a vehicle equipped with the position detection device. [Background technology]

[0002] Conventionally, position detection devices for detecting the position of moving members have been used, for example, in the movable parts of automobiles. The applicant has proposed a stroke sensor described in Patent Document 1 as such a position detection device.

[0003] The stroke sensor described in Patent Document 1 comprises a magnetic field detection unit such as a Hall IC, two parallel yokes that sandwich the magnetic field detection unit in the stroke direction of the stroke body, a magnetic path forming yoke that extends in the stroke direction of the stroke body at a predetermined distance between the two parallel yokes, a magnet positioned between one end of each of the two parallel yokes and the magnetic path forming yoke, a parallel magnetic field forming yoke that is movable between the two parallel yokes and the magnetic path forming yoke and faces the two parallel yokes, and a projection yoke integrally provided on the magnetic path forming yoke side of the parallel magnetic field forming yoke. In this stroke sensor, the strength of the magnetic field detected by the magnetic field detection unit changes according to the position of the parallel magnetic field forming yoke, so the position of the parallel magnetic field forming yoke can be detected by the strength of this magnetic field. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-98655 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In the stroke sensor described in Patent Document 1, it is necessary to arrange two parallel yokes and a magnetic path forming yoke so as to sandwich the parallel magnetic field forming yoke and the projection yoke over the entire range of movement of the parallel magnetic field forming yoke, which results in a large installation size for the stroke sensor. Therefore, the present invention aims to provide a position detection device that can be miniaturized, and a steering device for a vehicle equipped with the position detection device. [Means for solving the problem]

[0006] The present invention aims to solve the above problems and provides a position detection device for detecting the position of a moving member that moves back and forth in a predetermined direction of movement, comprising: a conductive detection member attached to the moving member; an excitation coil and a detection coil extending in the direction of movement of the moving member and facing the conductive detection member, wherein the conductive detection member has a recess formed therein that is recessed in a direction away from the excitation coil and the detection coil, and a voltage is induced in the detection coil by a current flowing through the conductive detection member due to the magnetic field generated by the excitation coil, and the magnitude of the voltage induced in the detection coil changes depending on the position of the recess relative to the detection coil.

[0007] Furthermore, the present invention aims to solve the above problems and provides a steering device for a vehicle comprising a shaft that moves axially back and forth along the width direction of the vehicle, a housing that houses the shaft, and a position detection device that detects the position of the shaft relative to the housing, wherein the wheels are steered as the shaft moves axially, the position detection device comprising a conductive detection member attached to the shaft, and an excitation coil and a detection coil that are arranged extending in the direction of movement of the shaft and facing the conductive detection member, wherein the conductive detection member has a recess formed therein that is recessed in a direction away from the excitation coil and the detection coil, and a voltage is induced in the detection coil by a current flowing through the conductive detection member due to the magnetic field generated by the excitation coil, and the magnitude of the voltage induced in the detection coil changes depending on the position of the recess relative to the detection coil. [Effects of the Invention]

[0008] According to the present invention, it becomes possible to miniaturize the position detection device. Furthermore, the miniaturization of the position detection device improves the ease of mounting the vehicle steering device onto a vehicle. [Brief explanation of the drawing]

[0009] [Figure 1] (a) is a schematic diagram showing a part of the configuration of a vehicle equipped with a steering device for a vehicle according to the first embodiment of the present invention. (b) is a cross-sectional view of (a) along line AA. [Figure 2] This is a perspective view showing the rack shaft, housing, lid component, and circuit board. [Figure 3] (a) is an overall view of the wiring patterns formed on the first to fourth metal layers of the substrate, seen through from the back side. (b) is a magnified view of a portion of (a). [Figure 4] (a) to (d) are plan views showing the first to fourth metal layers as seen from the reverse side. [Figure 5] This graph shows an example of the relationship between the supply voltage supplied from the power supply unit to the excitation coil and the induced voltage induced in the sinusoidal wave shape detection coil and the cosine wave shape detection coil. [Figure 6] (a) is a schematic diagram illustrating the relationship between the peak voltage, which is the peak value of the induced voltage induced in the sinusoidal shape detection coil, and the position of the recess. (b) is a schematic diagram illustrating the relationship between the peak voltage, which is the peak value of the induced voltage induced in the cosine wave shape detection coil, and the position of the recess. [Figure 7] This is a perspective view showing the detection target and substrate according to the second embodiment, together with the rack shaft, housing, and lid member. [Figure 8] (a) is an overall view of the wiring patterns formed on the first to fourth metal layers of the substrate, seen through from the back side. (b) is a magnified view of a portion of (a). [Figure 9] (a) to (d) are plan views showing the first to fourth metal layers as seen from the reverse side. [Figure 10] (a) to (c) are explanatory diagrams showing the relative positional relationship between the first and second detection coils and the first and second recesses in the substrate vertical direction. [Figure 11] It is a schematic diagram showing the dimensional relationship between the excitation coil and the first and second detection coils on the substrate, and the first and second recesses. [Figure 12] It is a perspective view showing a detection target according to a third embodiment. [Figure 13] It is an explanatory diagram showing the substrate and the detection target according to the third embodiment overlapped in the substrate vertical direction. [Figure 14] It is an explanatory diagram showing the substrate and the detection target according to the fourth embodiment overlapped in the substrate vertical direction.

Embodiments for Carrying Out the Invention

[0010] [First Embodiment] FIG. 1(a) is a schematic diagram showing a partial configuration of a vehicle equipped with a vehicle steering device 1 according to a first embodiment of the present invention. FIG. 1(b) is a cross-sectional view taken along line A-A of FIG. 1(a).

[0011] This vehicle steering device 1 is a steer-by-wire type steering device and includes a stroke sensor 10 as a position detection device. In FIG. 1(a), the state of the vehicle steering device 1 viewed from the rear side in the vehicle front-rear direction is shown. The right side of the drawing corresponds to the right side in the vehicle width direction, and the left side of the drawing corresponds to the left side in the vehicle width direction. In the following description referring to the drawings, there may be cases where "right" or "left" is mentioned, but this expression is used for convenience of explanation and does not limit the direction of the arrangement in the actual use state of the stroke sensor 10.

[0012] As shown in Figure 1(a), the vehicle steering device 1 includes tie rods 11 connected to the steering wheels 100 (left and right front wheels), a rack shaft 12 connected to the tie rods 11, a housing 13 that houses the rack shaft 12, a cover member 14 that closes the opening of the housing 13 (see Figure 1(b)), a worm reduction mechanism 15 having a pinion gear 151 that meshes with the rack teeth 121 of the rack shaft 12, an electric motor 16 that applies a moving force in the vehicle width direction to the rack shaft 12 via the worm reduction mechanism 15, a steering wheel 17 operated by the driver, 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.

[0013] The rack shaft 12 is a moving member whose position relative to the housing 13 is detected by the stroke sensor 10. The direction of movement of the rack shaft 12 is axial, parallel to the central axis C0 of the rack shaft 12. The steering wheel 100 is steered as the rack shaft 12 moves axially.

[0014] In Figure 1(a), the housing 13 is shown by dashed lines, and its interior is shown by solid lines. The rack shaft 12 is supported by a pair of rack bushings 131 attached to both ends of the housing 13. The worm reduction mechanism 15 has a worm wheel 152 and a worm gear 153, with a pinion gear 151 fixed to the worm wheel 152. The worm gear 153 is fixed to the motor shaft 161 of the electric motor 16.

[0015] The electric motor 16 generates torque from the motor current supplied by the steering control device 19, which rotates the worm wheel 152 and pinion gear 151 via the worm gear 153. As the pinion gear 151 rotates, the rack shaft 12 moves linearly forward and backward along the vehicle width direction. The rack shaft 12 can move to the right and left in the vehicle width direction within a predetermined range from the neutral position when the steering angle is zero.

[0016] In Figure 1(a), the stroke range R, which corresponds to the maximum travel distance of the rack shaft 12 when the steering wheel 17 is steered from the maximum steering angle of one side to the maximum steering angle of the other side, is indicated by a double arrow. The stroke sensor 10 can detect the position of the rack shaft 12 relative to the housing 13 throughout this stroke range R.

[0017] (Configuration of stroke sensor 10) The stroke sensor 10 comprises a detection target 2 as a conductive detection member attached to the rack shaft 12, a substrate 3 positioned opposite the detection target 2, a power supply unit 4, and a calculation unit 5. The detection target 2 is conductive, positioned between the rack shaft 12 and the substrate 3, and moves back and forth integrally with the rack shaft 12.

[0018] The stroke sensor 10 detects the axial (direction of movement) position of the rack shaft 12 relative to the housing 13 and outputs the detected position information to the steering control device 19. The steering control device 19 controls the electric motor 16 so that the position of the rack shaft 12 detected by the stroke sensor 10 corresponds to the steering angle of the steering wheel 17 detected by the steering angle sensor 18.

[0019] Figure 2 is a perspective view showing the rack shaft 12, housing 13, lid member 14, detection target 2, and substrate 3. Note that in Figure 2, the housing 13, lid member 14, detection target 2, and substrate 3 are shown spaced apart in the vertical direction of the drawing.

[0020] The rack shaft 12 is made of, for example, S45C carbon steel for machine structures, and in the portion to which the detection target 2 is attached, the cross-sectional shape perpendicular to the axial direction is circular. The diameter D of the rack shaft 12 is, for example, 25 mm. The housing 13 is made of, for example, die-cast aluminum alloy with a U-shaped cross-section and opens upward in the vertical direction. The opening 130 of the housing 13 is closed by a cover member 14. The rack shaft 12 and the housing 13 are electrically conductive.

[0021] As shown in Figure 1(b), a gap of, for example, 1 mm or more is formed between the outer circumferential surface 12a of the rack shaft 12 and the inner surface 13a of the housing 13. The lid member 14 is a non-conductive member formed in a flat plate shape. As the material for the lid member 14, a resin such as engineering plastic can be suitably used.

[0022] The detection target 2 is a conductive metal component and is fixed to the outer circumferential surface 12a of the rack shaft 12, for example, by welding. It is desirable that the metal material of the detection target 2 has a higher conductivity than the material of the rack shaft 12; for example, an aluminum alloy can be suitably used. However, the material of the detection target 2 may be the same as the material of the rack shaft 12. The surface 2a of the detection target 2 facing the substrate 3 is a plane parallel to the substrate 3. The mounting surface 2b of the detection target 2 to the rack shaft 12, which is the back surface of the facing surface 2a, is a concave surface curved with a curvature corresponding to the curvature of the outer circumferential surface 12a of the rack shaft 12.

[0023] The detection target 2 has a recess 20 formed in a direction perpendicular to the opposing surface 2a. The recess 20 traverses the opposing surface 2a in a direction perpendicular to the axial direction of the rack shaft 12 and is formed over the entire area between one side surface 2c and the other side surface 2d of the detection target 2.

[0024] The recess 20 is formed, for example, by cutting. Alternatively, the detection target 2 may be formed by casting, and the recess 20 may be formed by the shape of the mold. The material and processing method of the detection target 2 described here are also the same for the detection targets 2A, 2B, and 2C according to the second to fourth embodiments described later.

[0025] The bottom surface 20a of the recess 20 is a plane parallel to the opposing surface 2a, and the end faces 20b, 20b of the recess 20 face each other along the axial direction of the rack shaft 12, with the bottom surface 20a in between. The depth Dp of the recess 20 in the direction perpendicular to the opposing surface 2a is, for example, 5 mm. The rack shaft 12 is restricted from rotating relative to the housing 13 about the central axis C0 so that the opposing surface 2a of the detection target 2 always faces parallel to the substrate 3.

[0026] The substrate 3 is attached to the lid member 14 such that its front surface 3a faces the detection target 2. The opposing surface 2a of the detection target 2 faces the surface 3a of the substrate 3 via an air gap G of a predetermined width. The width W of the air gap G is, for example, 1 mm or less. The back surface 3b of the substrate 3 is fixed to the lid member 14 by adhesive 140.

[0027] The substrate 3 is a four-layer substrate in which a flat substrate 30 made of a dielectric material such as FR4 (glass fiber impregnated with epoxy resin and heat-cured) is arranged between the first to fourth metal layers 301 to 304. The thickness of each substrate 30 is, for example, 0.3 mm. The first to fourth metal layers 301 to 304 are made of, for example, copper, and the thickness of each layer is, for example, 18 μm. The substrate 3 is a flat rectangle with the axial direction of the rack shaft 12 being the long side direction (longitudinal direction). Note that the substrate 3 is not limited to a rigid substrate, but may also be a flexible substrate.

[0028] Figure 3(a) is an overall view of the wiring patterns formed on the first to fourth metal layers 301 to 304 of the substrate 3, as seen through from the back surface 3b. Figure 3(b) is a partially enlarged view of Figure 3(a). Figures 4(a) to 4(d) are plan views showing the first to fourth metal layers 301 to 304, respectively, as seen from the back surface 3b. Note that the wiring patterns shown in Figures 3(a) and (b) and Figures 4(a) to 4(d) are merely examples, and various forms of wiring patterns can be adopted as long as the substrate 3 is formed in a way that achieves the effects of the present invention.

[0029] In Figures 3(a) and 3(b), and Figures 4(a) to 4(d), the wiring pattern of the first metal layer 301 is shown with a solid line, the wiring pattern of the second metal layer 302 with a dashed line, the wiring pattern of the third metal layer 303 with a dashed-dotted line, and the wiring pattern of the fourth metal layer 304 with a double-dotted-dotted line. In Figure 3(a), the central axis C1 extending in the longitudinal direction after dividing the substrate 3 in the short direction is shown, and the positions of the recesses 20 when the rack shaft 12 is located at one end and the other end within the range in which the stroke sensor 10 can detect the position of the rack shaft 12 are shown with dotted lines. Note that the substrate 3 and the recesses 20 are aligned perpendicular to the substrate 3, but in Figure 3(a), the position of the recesses 20 is shown shifted in the short direction relative to the substrate 3.

[0030] A connector section 34 is provided at one longitudinal end of the substrate 3, having first to sixth through-holes 341 to 346 through which the connector pins of the connector 6, shown by the dashed line in Figure 3(b), are inserted. The first to sixth through-holes 341 to 346 are arranged in a straight line along the short direction of the substrate 3. Connector 71 (see Figure 1(a)) of the cable 7 for connection to the power supply unit 4 and the calculation unit 5 is connected to the connector 6. In addition, first to third vias 351 to 353 are formed on the substrate 3 for interlayer connection of wiring patterns.

[0031] On the substrate 3, an excitation coil 31 and a detection coil 32 are formed by wiring patterns formed on the first to fourth metal layers 301 to 304. The excitation coil 31 and the detection coil 32 extend in the direction of movement of the rack shaft 12 and face the detection target 2. The recess 20 is formed in a recessed direction away from the excitation coil 31 and the detection coil 32.

[0032] The first metal layer 301 has a curved portion 301a, a connector connection portion 301b that connects one end of the curved portion 301a to the second through-hole 342, and an end connection portion 301c that connects the respective ends of the curved portions 302a and 304a of the second metal layer 302 and the fourth metal layer 304, which will be described later. The second metal layer 302 has a curved portion 302a and a connector connection portion 302b that connects one end of the curved portion 302a to the fourth through-hole 344. The third metal layer 303 has a curved portion 303a and a connector connection portion 303b that connects one end of the curved portion 303a to the third through-hole 343. The fourth metal layer 304 has a curved portion 304a and a connector connection portion 304b that connects one end of the curved portion 304a to the fifth through-hole 345.

[0033] The curved portion 301a of the first metal layer 301 and the curved portion 303a of the third metal layer 303 are connected at their other ends by a first via 351. One end of the end connection portion 301c is connected to the other end of the curved portion 302a of the second metal layer 302 by a second via 352, and the other end is connected to the other end of the curved portion 304a of the fourth metal layer 304 by a third via 353.

[0034] The curved portions 301a, 302a, 303a, and 304a of the first to fourth metal layers 301 to 304 are sinusoidal curved conductor wires. The curved portion 301a of the first metal layer 301, the curved portion 303a of the third metal layer 303, the curved portion 302a of the second metal layer 302, and the curved portion 304a of the fourth metal layer 304 are symmetrical with respect to the central axis C1 of the substrate 3.

[0035] The detection coil 32 has a sinusoidal coil element 321 consisting of the curved portion 301a of the first metal layer 301 and the curved portion 303a of the third metal layer 303, and a cosine wave-shaped coil element 322 consisting of the curved portion 302a of the second metal layer 302, the curved portion 304a of the fourth metal layer 304, and the end connection portion 301c of the first metal layer 301. That is, each of the sinusoidal coil element 321 and the cosine wave-shaped coil element 322 has a shape that combines two sinusoidal curved conductor wires that are symmetrical with respect to the central axis C1 (the curved portion 301a of the first metal layer 301 and the curved portion 303a of the third metal layer 303, and the curved portion 302a of the second metal layer 302 and the curved portion 304a of the fourth metal layer 304). The central axis C1 is the axis of symmetry of the sinusoidal coil element 321 and the cosine wave coil element 322, and is parallel to the axial direction of the rack shaft 12.

[0036] The excitation coil 31 is rectangular in shape, having a pair of long sides 311, 312 extending in the axial direction of the rack shaft 12, and a pair of short sides 313, 314 between the pair of long sides 311, 312, and is formed to surround the detection coil 32. In this embodiment, the long sides 311, 312 and the short sides 313, 314 are formed as a wiring pattern on the first metal layer 301. As shown in Figure 3(b), of the pair of short sides 313 and 314, the short side 313 on the connector side 34 consists of two straight sides 313a and 313b that sandwich the first to fourth connector connection parts 301b, 302b, 303b, and 304b, and the ends of the two straight sides 313a and 313b are connected to the first through-hole 341 and the sixth through-hole 346 by connector connection parts 301d and 301e formed in the first metal layer 301.

[0037] Furthermore, the excitation coil 31 is not limited to the first metal layer 301, but may also be formed on any of the second to fourth metal layers 302 to 304, or it may be formed across multiple layers. In this embodiment, the excitation coil 31 and the detection coil 32 are formed on a single substrate 3, but the excitation coil 31 may be formed separately from the substrate 3.

[0038] A sinusoidal alternating current is supplied to the excitation coil 31 from the power supply unit 4. Eddy currents are generated in the detection target 2 by the magnetic flux generated by the alternating current supplied to the excitation coil 31. An induced voltage is generated in the detection coil 32 by the current in the detection target 2. The peak value of the voltage induced in the detection coil 32 changes depending on the position of the recess 20 relative to the detection coil 32. Here, the peak value of the voltage refers to the maximum absolute value of the voltage within one cycle of the alternating current supplied to the excitation coil 31.

[0039] As the rack shaft 12 moves from one axial end to the other, the phases of the voltages induced in the sinusoidal coil element 321 and the cosine wave coil element 322 of the detection coil 32 are different from each other. In this embodiment, the phases of the induced voltage of the sinusoidal coil element 321 and the induced voltage of the cosine wave coil element 322 are 90° apart.

[0040] The peak voltages induced in the sinusoidal coil element 321 and the cosine-shaped coil element 322 by the linking of the magnetic flux of the detection target 2 change within a range of less than one cycle while the rack shaft 12 moves from one moving end to the other in the axial direction. As a result, the stroke sensor 10 can detect the absolute position of the rack shaft 12 over the entire stroke range R in which the rack shaft 12 can move in the axial direction.

[0041] As shown in Figure 3(a), first and second buffer regions E1 and E2 are provided between each of the pair of short sides 313 and 314 of the excitation coil 31 and the sinusoidal coil element 321 and the cosinusoidal coil element 322, respectively, to suppress the voltage induced in the sinusoidal coil element 321 and the cosinusoidal coil element 322 by the magnetic flux generated by the current flowing through the pair of short sides 313 and 314.

[0042] Figure 5 is a graph showing an example of the relationship between the supply voltage V0 supplied from the power supply unit 4 to the excitation coil 31 and the induced voltage V1 induced in the sinusoidal coil element 321 and the induced voltage V2 induced in the cosine wave coil element 322. In the graph of Figure 5, the horizontal axis is the time axis, and the left and right vertical axes show the supply voltage V0 and the induced voltages V1 and V2. For example, a high-frequency AC voltage of about 1 MHz is supplied to the excitation coil 31 as the supply voltage V0. The induced voltages V1 and V2 are output to the calculation unit 5 via the cable 7 as the output voltages of the sinusoidal coil element 321 and the cosine wave coil element 322.

[0043] In the example shown in Figure 5, the supply voltage V0 and the induced voltages V1 and V2 are in phase. However, the induced voltage V1 induced in the sinusoidal shape detection coil element 321 switches between in phase and out of phase when the recess 20 passes through a position corresponding to the intersection of the curved portion 301a of the first metal layer 301 and the curved portion 303a of the third metal layer 303, as viewed from a direction perpendicular to the surface 3a and back surface 3b of the substrate 3. Similarly, the induced voltage V2 induced in the cosine wave shape detection coil element 322 switches between in phase and out of phase when the recess 20 passes through a position corresponding to the intersection of the curved portion 302a of the second metal layer 302 and the curved portion 304a of the fourth metal layer 304, as viewed from a direction perpendicular to the substrate.

[0044] Figure 6(a) shows the peak voltage V, which is the peak value of the induced voltage V1 induced in the sinusoidal coil element 321. S This is an explanatory diagram schematically showing the relationship between the position of the recess 20 and the other element. Figure 6(b) shows the peak voltage V, which is the peak value of the induced voltage V2 induced in the cosine wave coil element 322. C This is an explanatory diagram that schematically shows the relationship between the position of the recess 20 and the surrounding area.

[0045] The peak voltage V shown in Figures 6(a) and (b) S ,V CIn the graph, the horizontal axis shows the position of the center of the recess 20 in the left-right direction. P1 on the horizontal axis shows the position of the center point 20c of the recess 20 when the left end of the recess 20 coincides with the left ends of the sinusoidal coil element 321 and the cosine wave coil element 322. P2 on the horizontal axis shows the position of the center point 20c of the recess 20 when the right end of the recess 20 coincides with the right ends of the sinusoidal coil element 321 and the cosine wave coil element 322. In Figures 6(a) and (b), the recess 20 when the center point 20c is at position P1 and the recess 20 when the center point 20c is at position P2 are shown by dashed lines. Here, the center point 20c of the recess 20 is the center point of the bottom surface 20a, as shown in Figure 2.

[0046] The sinusoidal coil element 321 and the cosine wave coil element 322 have a stronger magnetic field strength in the portion facing the surface 2a of the detection target 2, excluding the portion where the recess 20 is formed, than in the portion facing the recess 20. Therefore, the output voltage of the sinusoidal coil element 321 and the cosine wave coil element 322 changes according to the position of the rack shaft 12 due to the difference in the strength of these magnetic fields. In the graph shown in Figure 6(a), the peak voltage V S In this case, a positive value is defined when the induced voltage V1 induced in the sinusoidal coil element 321 is in phase with the supply voltage V0 supplied to the excitation coil 31, and a negative value is defined when it is out of phase. Also, in the graph shown in Figure 6(b), the peak voltage V C In this configuration, a positive value is defined when the induced voltage V2 induced in the cosine wave-shaped coil element 322 is in phase with the supply voltage V0 supplied to the excitation coil 31, and a negative value is defined when it is out of phase.

[0047] When the rack shaft 12 moves in one direction at a constant speed from one moving end to the other moving end, the peak voltage V is as shown in Figures 6(a) and (b). S The waveform changes sinusoidally, and the peak voltage V C The voltage changes in a cosine wave pattern. Therefore, the calculation unit 5 can determine the position of the rack shaft 12 by calculation based on the output voltages of the sinusoidal coil element 321 and the cosine wave coil element 322.

[0048] As shown in Figure 3(a), the position of the left end of the sinusoidal shape detection coil element 321 and the cosine wave shape detection coil element 322 in the longitudinal direction of the substrate 3 is defined as the reference position O, the length of the sinusoidal shape coil element 321 and the cosine wave shape coil element 322 in the longitudinal direction of the substrate 3 is defined as L, the position X of the rack shaft 12 when the center point 20c of the recess 20 is aligned with the reference position O in the direction perpendicular to the substrate is defined as 0 (zero), and the direction toward the right end of the sinusoidal shape coil element 321 and the cosine wave shape coil element 322 from the reference position O is defined as the positive side of the position X of the rack shaft 12, then the position X of the rack shaft 12 can be determined by the following formula (1).

number

[0049] The calculation unit 5 outputs the position determined by equation (1) based on the output voltages of the sinusoidal coil element 321 and the cosine wave coil element 322 to the steering control device 19 as the position of the rack shaft 12.

[0050] When u is the ratio of the length of the recess 20 in the axial direction of the rack shaft 12 to the length L of the sinusoidal coil element 321 and the cosine wave coil element 322, the calculation unit 5 can determine the position of the rack shaft 12 within a range of length (1-u)L. The length of the detection target 2 in the axial direction of the rack shaft 12 is 2(1-u)L or more. Therefore, the detection coil 32, except for the portion facing the recess 20, always faces the opposing surface 2a of the detection target 2 while the rack shaft 12 moves from one end to the other in the axial direction.

[0051] Note that u is a value less than 0.5. A smaller value of u allows for detection of the rack shaft 12's position over longer distances. However, if u is too small, the induced voltages V1 and V2 become small, leading to larger errors. Therefore, it is desirable for u to be, for example, between 0.01 and 0.5.

[0052] (Effects of the first embodiment) According to the first embodiment described above, the position of the rack shaft 12 can be detected by positioning the detection target 2 attached to the rack shaft 12 facing the substrate 3, thus reducing the installation size of the stroke sensor 10. Furthermore, by reducing the installation size of the stroke sensor 10, it becomes possible to make the vehicle steering device 1 smaller and lighter.

[0053] [Second Embodiment] Next, a second embodiment of the present invention will be described with reference to Figures 7 to 11. For components of the second embodiment shown in Figures 7 to 11 that are common to the first embodiment, the same reference numerals used in the first embodiment are used, and redundant explanations are omitted.

[0054] Figure 7 is a perspective view showing the detection target 2A and substrate 3A according to this embodiment together with the rack shaft 12, housing 13, and lid member 14.

[0055] In the first embodiment, the case in which the rack shaft 12 to which the detection target 2 is attached has a circular cross-section was described. However, in this embodiment, a flat portion 122 is formed on the rack shaft 12, and the cross-section of the rack shaft 12 to which the detection target 2A is attached is D-shaped.

[0056] The detection target 2A is a flat plate with its longitudinal direction aligned with the axial direction of the rack shaft 12, and its surface 2a facing the substrate 3A is a plane parallel to the substrate 3A. The mounting surface 2b of the detection target 2A to the rack shaft 12 is a plane parallel to the opposing surface 2a. The detection target 2A is fixed to the rack shaft 12 by, for example, welding, with its mounting surface 2b in contact with the flat portion 122 of the rack shaft 12.

[0057] The detection target 2A has first and second recesses 201 and 202 formed therein, which are recessed in the direction away from the substrate 3A. The first recess 201 opens on one of the two sides 2c and 2d of the detection target 2A, side 2c, and the second recess 202 opens on the other side 2d. In this embodiment, the first and second recesses 201 and 202 penetrate through the plate thickness direction between the opposing surface 2a and the mounting surface 2b of the detection target 2A.

[0058] Figure 8(a) is an overall view of the wiring patterns formed on the first to fourth metal layers 301 to 304 of substrate 3A, as seen through from the back surface 3b. Figure 8(b) is a magnified view of a portion of Figure 8(a). Figures 9(a) to 9(d) are plan views showing the first to fourth metal layers 301 to 304, respectively, as seen from the back surface 3b.

[0059] In the first embodiment, a case was described in which one detection coil 32 is formed on the substrate 3. In this embodiment, in addition to the detection coil 32, a second detection coil 33, configured similarly to the detection coil 32, is formed on the substrate 3A. Hereinafter, the two detection coils 32 and 33 will be referred to as the first detection coil 32 and the second detection coil 33, respectively.

[0060] The first recess 201 of the detection target 2A is formed corresponding to the first detection coil 32. The second recess 202 is formed corresponding to the second detection coil 33. In Figure 8(a), the positions of the first recess 201 and the second recess 202 are shown in gray shading when the rack shaft 12 is positioned at the center of the range in which the position of the rack shaft 12 can be detected by the first and second detection coils 32 and 33.

[0061] On the substrate 3A, an excitation coil 31 is formed such that it encloses the first detection coil 32 and the second detection coil 33 together. The excitation coil 31 extends in the direction of movement of the rack shaft 12, and the first detection coil 32 and the second detection coil 33 are formed side by side in a direction perpendicular to the direction of extension of the excitation coil 31 (the short side direction of the substrate 3A).

[0062] The substrate 3A is a four-layer substrate having first to fourth metal layers 301 to 304. The first metal layer 301 has a curved portion 301a, a connector connection portion 301b, an end connection portion 301c, and long sides 311, 312 and short sides 313, 314, as well as a curved portion 301f, a connector connection portion 301g, an end connection portion 301h, and connector connection portions 301i and 301j. The second metal layer 302 has a curved portion 302a and a connector connection portion 302b, as well as a curved portion 302e and a connector connection portion 302f. The third metal layer 303 has a curved portion 303a and a connector connection portion 303b, as well as a curved portion 303e and a connector connection portion 303f. In addition to the curved portion 304a and the connector connection portion 304b, the fourth metal layer 304 has a curved portion 304e and a connector connection portion 304f formed thereon.

[0063] Furthermore, a connector section 36 consisting of first to tenth through-holes 360 to 369 is formed on the substrate 3A. Similar to the first embodiment, a connector 6 is connected to the connector section 36, which is fitted to a connector 71 of a cable 7 for connecting the substrate 3A to the power supply unit 4 and the calculation unit 5. In addition to the first to third vias 351 to 353, fourth to sixth vias 354 to 356 for interlayer connection are formed on the substrate 3A. These components of the substrate 3A are connected as shown in Figures 8 and 9 to form the excitation coil 31 and the first and second detection coils 32 and 33.

[0064] The first detection coil 32, similar to the detection coil 32 of the first embodiment, has a sinusoidal coil element 321 consisting of a curved portion 301a of the first metal layer 301 and a curved portion 303a of the third metal layer 303, and a cosine wave coil element 322 consisting of a curved portion 302a of the second metal layer 302, a curved portion 304a of the fourth metal layer 304, and an end connection portion 301c of the first metal layer 301.

[0065] The second detection coil 33 includes a sinusoidal coil element 331 consisting of the curved portion 301f of the first metal layer 301 and the curved portion 303e of the third metal layer 303, and a cosine wave-shaped coil element 332 consisting of the curved portion 302e of the second metal layer 302, the curved portion 304e of the fourth metal layer 304, and the end connection portion 301h of the first metal layer 301.

[0066] The substrate 3A is rectangular in shape with the axial direction of the rack shaft 12 as its longitudinal direction. The sinusoidal coil element 321 and cosine wave coil element 322 of the first detection coil 32 are symmetrical with respect to a first axis of symmetry C2 along the longitudinal direction of the substrate 3A. The sinusoidal coil element 331 and cosine wave coil element 332 of the second detection coil 33 are symmetrical with respect to a second axis of symmetry C3 parallel to the first axis of symmetry C2. The first detection coil 32 and the second detection coil 33 have the same length in the longitudinal direction of the substrate 3A and the same width in the short direction of the substrate 3A.

[0067] When the rack shaft 12 moves at a constant speed in one direction, the peak voltage of the induced voltage induced in the sinusoidal coil element 321 changes sinusoidally while the first recess 201 is facing the first detection coil 32, and the peak voltage of the induced voltage induced in the cosine wave coil element 322 changes cosineally while the first recess 201 is facing the first detection coil 32. These induced voltages are output to the calculation unit 5 as the output voltages of the sinusoidal coil element 321 and the cosine wave coil element 322. The calculation unit 5 can calculate the position of the rack shaft 12 based on the output voltages of the sinusoidal coil element 321 and the cosine wave coil element 322.

[0068] Similarly, with respect to the second detection coil 33, when the rack shaft 12 moves at a constant speed in one direction, while the second recess 202 is in a position facing the second detection coil 33, the peak voltage, which is the peak value of the induced voltage induced in the sinusoidal coil element 331, changes sinusoidally, and the peak voltage, which is the peak value of the induced voltage induced in the cosine wave coil element 332, changes cosineally. These induced voltages are output to the calculation unit 5 as the output voltages of the sinusoidal coil element 331 and the cosine wave coil element 332. Based on the output voltages of the sinusoidal coil element 331 and the cosine wave coil element 332, the calculation unit 5 can determine the position of the rack shaft 12 by calculation.

[0069] Figures 10(a) to (c) are explanatory diagrams showing the relative positional relationship between the first and second detection coils 32, 33 and the first and second recesses 201, 202 in the direction perpendicular to the substrate. In Figures 10(a) to (c), the excitation coil 31, the first and second detection coils 32, 33, and the detection target 2A are shown superimposed in the direction perpendicular to the substrate, viewed through the substrate 30 from the back surface 3b side of the substrate 3A. In Figures 10(a) to (c), the detection target 2A is shown in light gray, and the first and second recesses 201, 202 are shown in dark gray. Furthermore, Figures 10(a) to (c) show the center point 300 of the area on the substrate 3A where the first and second detection coils 32, 33 are formed, the center points 201c, 202c of the first and second recesses 201, 202, and the midpoint 200 of these center points 201c, 202c.

[0070] Figure 10(a) shows the state where the steering angle of the steering wheel 17 is zero, the rack shaft 12 is in the neutral position, and the midpoint 200 and the center point 300 coincide. In this state, the left end of the first recess 201 coincides with the left end of the first detection coil 32, and the right end of the second recess 202 coincides with the right end of the second detection coil 33.

[0071] Figure 10(b) shows the state in which the right end of the first recess 201 coincides with the right end of the first detection coil 32. Let L1 be the distance between the midpoint 200 and the center point 300 in this state. The range of this distance L1 is the detectable range in which the position of the detection target 2A can be detected by the first detection coil 32.

[0072] Figure 10(c) shows the state in which the left end of the second recess 202 coincides with the left end of the second detection coil 33. Let L2 be the distance between the midpoint 200 and the center point 300 in this state. The range of this distance L2 is the detectable range in which the position of the detection target 2A can be detected by the second detection coil 33.

[0073] Thus, the detectable range in which the position of the detection target 2A can be detected by the first detection coil 32 and the detectable range in which the position of the detection target 2A can be detected by the second detection coil 33 are offset in the direction of movement of the rack shaft 12. Furthermore, at the neutral position of the rack shaft 12, the position of the detection target 2A can be detected by both the first detection coil 32 and the second detection coil 33. In other words, the detectable range in which the position of the detection target 2A can be detected by the first detection coil 32 and the detectable range in which the position of the detection target 2A can be detected by the second detection coil 33 overlap in some respects and are continuous in the direction of movement of the rack shaft 12.

[0074] The calculation unit 5 can calculate the position of the rack shaft 12 within an axial range of length L1 + L2, centered on the neutral position of the rack shaft 12. The length L1 + L2 is the same as or longer than the stroke range R of the rack shaft 12 (see Figure 1), making it possible to detect the position of the rack shaft 12 over the entire stroke range R.

[0075] Figure 11 is a schematic diagram showing the dimensional relationship between the excitation coil 31 and the first and second detection coils 32, 33 on the substrate 3A and the first and second recesses 201, 202. In Figure 11, the axial direction of the rack shaft 12 is defined as the x-axis direction, and the direction parallel to the substrate 3A and perpendicular to the x-axis direction is defined as the y-axis direction. In addition, in Figure 11, the dimensions of the excitation coil 31 and the first and second detection coils 32, 33 in the y-axis direction are enlarged by a factor of two, and the distance between the first detection coil 32 and the second detection coil 33 is shown widened in the y-axis direction.

[0076] The origin of the x-axis is the position of the center point 201c of the first recess 201 in the state shown in Figure 10(c), and the origin of the y-axis is the position of one of the long sides 312 of the excitation coil 31. Coordinate point X1 on the x-axis indicates the position in the x-axis direction of the center point 201c of the first recess 201 in the state shown in Figure 10(a), and coordinate point X2 on the x-axis indicates the position in the x-axis direction of the center point 202c of the second recess 202 in the state shown in Figure 10(a). Coordinate point X3 on the x-axis indicates the position in the x-axis direction of the center point 202c of the second recess 202 in the state shown in Figure 10(b). Coordinate point 200' is the midpoint 200 of the center points 201c and 202c of the first and second recesses 201 and 202 in the state shown in Figure 10(c), and coordinate point 200'' is the midpoint 200 of the center points 201c and 202c of the first and second recesses 201 and 202 in the state shown in Figure 10(b).

[0077] In Figure 11, L is the x-axis length of the first and second detection coils 32 and 33. u is the ratio of the x-axis lengths of the first and second recesses 201 and 202 to L. Δp1 is the x-axis distance from the left ends of the first and second detection coils 32 and 33 to the center point 201c of the first recess 201. Δp2 is the x-axis distance from the left ends of the first and second detection coils 32 and 33 to the center point 202c of the second recess 202.

[0078] When the first recess 201 overlaps the sinusoidal coil element 321 and the cosine wave coil element 322 of the first detection coil 32 in the direction perpendicular to the substrate, Δp1 can be calculated by the following equation (2).

Number

[0079] Also, when the second recess 202 overlaps with the sine-wave-shaped coil element 331 and the cosine-wave-shaped coil element 332 of the second detection coil 33 in the direction perpendicular to the substrate, Δp2 can be obtained by the following formula (3).

Number

[0080] The arithmetic unit 5 can obtain the position of the rack shaft 12 by calculation according to formula (2) or formula (3). The moving distance of the rack shaft 12 in the x-axis direction in which the arithmetic unit 5 can obtain the position of the rack shaft 12 according to formula (2), and the moving distance of the rack shaft 12 in the x-axis direction in which the absolute position of the rack shaft 12 can be obtained according to formula (3) are both (1 - u)L. Therefore, in this embodiment, the total moving distance of the rack shaft 12 in which the arithmetic unit 5 can obtain the position of the rack shaft 12 is 2(1 - u)L.

[0081] This 2(1-u)L travel distance is longer than (1-u)L, which is the travel distance of the rack shaft 12 that allows the position of the rack shaft 12 to be determined in the first embodiment. In other words, in the second embodiment, the length L of the first detection coil 32 and the second detection coil 33 that allows the position of the rack shaft 12 to be detected is longer than in the first embodiment. To put it another way, the length L of the first detection coil 32 and the second detection coil 33 is shorter than the length L of the rack shaft 12 that allows the position of the rack shaft 12 to be detected.

[0082] Therefore, according to the second embodiment, the length of the substrate 3A can be shortened, and the installation size can be made even smaller than in the first embodiment.

[0083] [Third Embodiment] Next, a third embodiment of the present invention will be described with reference to Figures 12 and 13. Figure 12 is a perspective view showing a detection target 2B according to the third embodiment. Figure 13 is an explanatory diagram showing the substrate 3B and the detection target 2B according to the third embodiment superimposed in the direction perpendicular to the substrate. Similar to the second embodiment, the detection target 2B is a rectangular flat plate with the axial direction of the rack shaft 12 as its longitudinal direction, and is attached to the flat portion 122 of the rack shaft 12, for example, by welding.

[0084] The substrate 3B has first and second detection coils 32 and 33, third and fourth detection coils 37 and 38, and an excitation coil 39 formed on it. The substrate 3B is a four-layer substrate, similar to the first and second embodiments, and the first and second detection coils 32 and 33, the third and fourth detection coils 37 and 38, and the excitation coil 39 are formed distributed in each layer.

[0085] The configuration of the first and second detection coils 32 and 33 is the same as in the second embodiment. The third and fourth detection coils 37 and 38 each have sinusoidal coil elements 371 and 381 and cosine wave coil elements 372 and 382, ​​respectively, but their size differs from that of the sinusoidal coil elements 321 and 331 and cosine wave coil elements 322 and 332 of the first and second detection coils 32 and 33, and they are formed to be shorter in the axial direction of the rack shaft 12.

[0086] The excitation coil 39 is formed to enclose the first and second detection coils 32, 33 and the third and fourth detection coils 37, 38 together, and is connected to the power supply unit 4 via the connector 6 and cable 7. The first and second detection coils 32, 33 and the third and fourth detection coils 37, 38 are connected to the calculation unit 5 via the connector 6 and cable 7.

[0087] The detection target 2B has a plurality of first recesses 203 corresponding to the first detection coil 32, a plurality of second recesses 204 corresponding to the second detection coil 33, a plurality of third recesses 205 corresponding to the third detection coil 37, and a plurality of fourth recesses 206 corresponding to the fourth detection coil 38, all formed in the axial direction of the rack shaft 12. The plurality of first recesses 203, second recesses 204, third recesses 205, and fourth recesses 206 are formed to penetrate the detection target 2B in the thickness direction.

[0088] Multiple first recesses 203 are formed at predetermined intervals along the longitudinal direction of the detection target 2B. Multiple second recesses 204 are formed at the same predetermined intervals along the longitudinal direction of the detection target 2B as the multiple first recesses 203. Multiple third recesses 205 are formed at predetermined intervals that are narrower than the intervals between the multiple first recesses 203 along the longitudinal direction of the detection target 2B. Multiple fourth recesses 206 are formed at the same predetermined intervals along the longitudinal direction of the detection target 2B as the multiple third recesses 205.

[0089] As the rack shaft 12 moves from one end to the other in the axial direction, the first detection coil 32 and the plurality of first recesses 203 face each other in the direction perpendicular to the substrate, and the second detection coil 33 and the plurality of second recesses 204 face each other in the direction perpendicular to the substrate. Also, as the rack shaft 12 moves from one end to the other in the axial direction, the third detection coil 37 and the plurality of third recesses 205 face each other in the direction perpendicular to the substrate, and the fourth detection coil 38 and the plurality of fourth recesses 206 face each other in the direction perpendicular to the substrate.

[0090] The detection range of the multiple first recesses 203 detected by the first detection coil 32 and the detection range of the multiple second recesses 204 detected by the second detection coil 33 overlap in part and are continuous in the direction of movement of the rack shaft 12. Furthermore, the detection range of the multiple third recesses 205 detected by the third detection coil 37 and the detection range of the multiple fourth recesses 206 detected by the fourth detection coil 38 overlap in part and are continuous in the direction of movement of the rack shaft 12.

[0091] When the rack shaft 12 moves in one direction, the distance the rack shaft 12 moves while the peak voltage values ​​induced in the first and second detection coils 32, 33 change by one cycle is different from the distance the rack shaft 12 moves while the peak voltage values ​​induced in the third and fourth detection coils 37, 38 change by one cycle. In this embodiment, depending on the difference between the lengths of the first and second detection coils 32, 33 in the axial direction of the rack shaft 12 and the lengths of the third and fourth detection coils 37, 38 in the axial direction of the rack shaft 12, the distance the rack shaft 12 moves while the peak voltage values ​​induced in the third and fourth detection coils 37, 38 change by one cycle is shorter than the distance the rack shaft 12 moves while the peak voltage values ​​induced in the first and second detection coils 32, 33 change by one cycle.

[0092] X is the distance the rack shaft 12 travels while the peak voltage values ​​induced in the first and second detection coils 32 and 33 change by one cycle. 12Let X be the distance the rack shaft 12 moves while the peak value of the voltage induced in the third and fourth detection coils 37 and 38 changes by one cycle. 34 When X 34 is X 12 Longer than half of X 12 is X 34 It is a non-integer multiple of . As a result, the calculation unit 5 can calculate the absolute position of the rack shaft 12 over a longer distance than in the second embodiment by comparing the position of the first recess 203 or the second recess 204, which is determined by the output signal of the first detection coil 32 or the second detection coil 33, with the position of the third recess 205 or the fourth recess 206, which is determined by the output signal of the third detection coil 37 or the fourth detection coil 38. Furthermore, if the length of the stroke range of the rack shaft 12 is the same as in the second embodiment, the longitudinal length of the substrate 3B can be made even shorter than the longitudinal length of the substrate 3A according to the second embodiment.

[0093] [Fourth Embodiment] Next, a fourth embodiment of the present invention will be described with reference to Figure 14. Figure 14 is an explanatory diagram showing the substrate 3C and the detection target 2C according to the fourth embodiment superimposed in the direction perpendicular to the substrate. The substrate 3C is configured in the same way as the substrate 3A according to the second embodiment. The detection target 2C is a rectangular flat plate with the axial direction of the rack shaft 12 as its longitudinal direction, similar to the second embodiment, and is attached to the flat portion 122 of the rack shaft 12, for example, by welding.

[0094] The detection target 2C has a plurality of first recesses 207 corresponding to the first detection coil 32, spaced apart in the axial direction of the rack shaft 12, and a plurality of second recesses 208 corresponding to the second detection coil 33, also spaced apart in the axial direction of the rack shaft 12. The plurality of first recesses 207 and second recesses 208 are formed to penetrate the detection target 2C in the thickness direction. The plurality of first recesses 207 open on one side surface 2c of the detection target 2C, and the plurality of second recesses 208 open on the other side surface 2d of the detection target 2C.

[0095] The detection range of the first recess 207 by the first detection coil 32 and the detection range of the second recess 208 by the second detection coil 33 overlap in part and are continuous in the direction of movement of the rack shaft 12. As the rack shaft 12 moves from one end to the other, the multiple first recesses 207 face the first detection coil 32, and the multiple second recesses 208 face the second detection coil 33.

[0096] The multiple first recesses 207 each have different lengths in the axial direction of the rack shaft 12. Similarly, the multiple second recesses 208 each have different lengths in the axial direction of the rack shaft 12.

[0097] The magnitude of the induced voltage induced in the first detection coil 32 varies depending on the length of the first recess 207, and the magnitude of the induced voltage induced in the second detection coil 33 varies depending on the length of the second recess 208. Therefore, the calculation unit 5 can determine which of the multiple first recesses 207 is facing the first detection coil 32, and which of the multiple second recesses 208 is facing the second detection coil 33, based on the magnitude of the induced voltage. This makes it possible to calculate the absolute position of the rack shaft 12 over a longer distance than in the second embodiment. Furthermore, if the length of the stroke range of the rack shaft 12 is the same as in the second embodiment, the longitudinal length of the substrate 3B can be made even shorter than the longitudinal length of the substrate 3A in the second embodiment.

[0098] (Summary of the embodiments) Next, the technical concept understood from the first to fourth embodiments described above will be described using the reference numerals and other symbols from each embodiment. However, the reference numerals in the following description are not limited to the components in the claims that are specifically shown in the embodiments.

[0099] [1] A position detection device (stroke sensor 10) for detecting the position of a moving member (rack shaft 12) that moves back and forth in a predetermined direction of movement, comprising: conductive detection members (detection targets 2, 2A, 2B, 2C) attached to the moving member (12); excitation coils (31, 39) and detection coils (32, 33, 37, 38) extending in the direction of movement of the moving member (12) and facing the conductive detection members (2, 2A, 2B, 2C), wherein the conductive detection members (2, 2A, 2B, 2C) are connected to the excitation coils (31, 39) and A position detection device (10) is provided, wherein recesses (20, 203~208) are formed in a direction away from the detection coils (32, 33, 37, 38), and a voltage is induced in the detection coils (32, 33, 37, 38) by the current flowing through the conductive detection members (2, 2A, 2B, 2C) due to the magnetic field generated by the excitation coils (31, 39), and the magnitude of the voltage induced in the detection coils (32, 33, 37, 38) changes depending on the position of the recesses (20, 203~208) relative to the detection coils (32, 33, 37, 38).

[0100] [2] The position detection device (10) according to [1] above, wherein the excitation coils (31, 39) and the detection coils (32, 33, 37, 38) are formed on a single substrate (3, 3A, 3B, 3C), the conductive detection member (2, 2A, 2B, 2C) has a facing surface (2a) that faces the substrate (3, 3A, 3B, 3C) via an air gap (G) of a predetermined width, the facing surface (2a) is a plane parallel to the substrate (3, 3A, 3B, 3C), and the recesses (20, 203~208) are formed as depressions perpendicular to the facing surface (2a).

[0101] [3] The position detection device (10) described in [1] above, wherein the detection coil (32, 33, 37, 38) has a pair of coil elements (sine wave shaped coil elements 321, 331, 371, 381, cosine wave shaped coil elements 322, 332, 372, 382) whose output voltage changes according to the position of the moving member (12), and the phases of the output voltages of each of the pair of coil elements (321, 331, 371, 381, 322, 332, 372, 382) are different from each other when the moving member (12) is moving.

[0102] [4] Each of the pair of coil elements (321, 331, 371, 381, 322, 332, 372, 382) is a combination of two sinusoidal conductor wires (301a, 301f, 302a, 302e, 303a, 303e, 304a, 304e) that are symmetrical across a symmetric axis (C1, C2, C3) parallel to the direction of movement, and the output voltage changes according to the position of the moving member (12) based on the difference between the magnetic field strength in the portion facing the recess (20, 203~208) and the magnetic field strength in the portion not facing the recess (20, 203~208), as described in [3] above, the position detection device (10).

[0103] [5] A position detection device (10) as described in [1] above, having a plurality of detection coils (32, 33, 37, 38) arranged perpendicular to the extension direction of the excitation coils (31, 39), the conductive detection member (2, 2A, 2B, 2C) having a plurality of recesses (20, 203~208) corresponding to the plurality of detection coils (32, 33, 37, 38) at different positions in the direction of movement, and the detectable range in which the position of the moving member (12) can be detected by each of the plurality of detection coils (32, 33, 37, 38) is offset in the direction of movement of the moving member (12).

[0104] [6] The position detection device (10) according to [5] above, wherein the plurality of detection coils (32, 33, 37, 38) include a first detection coil (32) and a second detection coil (33), and the detectable range of the first detection coil (32) and the detectable range of the second detection coil (33) overlap in part and are continuous in the direction of movement.

[0105] [7] The position detection device (10) according to [6] above, wherein, while the moving member (12) moves from one end of the movement direction to the other end of the movement direction, the first detection coil (32) and the second detection coil (33) each face a plurality of recesses (203, 204, 207, 208) which are spaced apart in the movement direction.

[0106] [8] The position detection device (10) according to [7] above, wherein the length of each of the plurality of recesses (207) facing the first detection coil (32) is different in the direction of movement as the moving member (12) moves from one moving end to the other moving end, and the length of each of the plurality of recesses (208) facing the second detection coil (33) is different in the direction of movement as the moving member (12) moves from one moving end to the other moving end.

[0107] [9] The position detection device (10) described in [1] above, wherein the recesses (203-208) are formed to penetrate the conductive detection members (2A, 2B, 2C) in a direction away from the excitation coils (31, 39) and the detection coils (32, 33, 37, 38).

[0108]

[10] A steering device for a vehicle (1) comprising a shaft (12) that moves axially along the width direction of the vehicle, a housing (13) that houses the shaft (12), and a position detection device (10) that detects the position of the shaft (12) relative to the housing (13), wherein the wheels (steering wheels 100) are steered as the shaft (12) moves axially, the position detection device (10) comprises conductive detection members (detection targets 2, 2A, 2B, 2C) attached to the shaft (12), and excitation coils (31, 39) and detection coils (3) that extend in the direction of movement of the shaft (12) and face the conductive detection members (2, 2A, 2B, 2C). A steering device for a vehicle (1) comprising: 2, 33, 37, 38), wherein the conductive detection member (2, 2A, 2B, 2C) has recesses (20, 203~208) formed in the direction away from the excitation coil (31, 39) and the detection coil (32, 33, 37, 38), and a voltage is induced in the detection coil (32, 33, 37, 38) by the current flowing through the conductive detection member (2, 2A, 2B, 2C) due to the magnetic field generated by the excitation coil (31, 39), and the magnitude of the voltage induced in the detection coil (32, 33, 37, 38) changes depending on the position of the recesses (20, 203~208) relative to the detection coil (32, 33, 37, 38).

[0109] Although embodiments of the present invention have been described above, these embodiments do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. [Explanation of symbols]

[0110] 1... Steering device for vehicles 10… Stroke sensor (position detection device) 100... Steering wheel 12…Rack shaft (movable component) 2, 2A, 2B, 2C... Detection targets (conductive detection members) 20,203~208…recess 2a...Opposing surface 3,3A,3B,3C…board 301a, 301f, 302a, 302e, 303a, 303e, 304a...Curved section 31, 39… Excitation coil 32...First detection coil 33...Second detection coil 321,331…Sine wave shaped coil elements 322,332… Cosine wave shaped coil elements 37...Third detection coil 38...Fourth detection coil 371,381…Sine wave shaped coil elements 372,382… Cosine wave shaped coil elements

Claims

1. A position detection device for detecting the position of a moving member that moves back and forth in a predetermined direction, A conductive detection member attached to the moving member, The moving member comprises an excitation coil and a detection coil that extend in the direction of movement of the moving member and face the conductive detection member, The conductive detection member has a recess formed in the direction away from the excitation coil and the detection coil, The magnetic field generated by the excitation coil induces a current flowing through the conductive detection member, which in turn induces a voltage in the detection coil. The magnitude of the voltage induced in the detection coil changes depending on the position of the recess relative to the detection coil. Position detection device.

2. The excitation coil and the detection coil are formed on a single substrate. The conductive detection member has an opposing surface that faces the substrate via an air gap of a predetermined width, the opposing surface is a plane parallel to the substrate, and the recess is formed as a depression perpendicular to the opposing surface. The position detection device according to claim 1.

3. The detection coil has a pair of coil elements whose output voltage changes according to the position of the moving member, and the phases of the output voltages of the pair of coil elements are different from each other when the moving member is moving. The position detection device according to claim 1.

4. Each of the pair of coil elements has a shape formed by combining two sinusoidal conductor wires that are symmetrical with respect to a symmetry axis parallel to the direction of movement, and the output voltage changes according to the position of the moving member due to the difference between the magnetic field strength in the portion facing the recess and the magnetic field strength in the portion not facing the recess. The position detection device according to claim 3.

5. The device has a plurality of detection coils, and these plurality of detection coils are arranged in a direction perpendicular to the extending direction of the excitation coil. The conductive detection member has a plurality of recesses that correspond to a plurality of detection coils and are provided at different positions in the direction of movement. The detectable range in which the position of the moving member can be detected by each of the multiple detection coils is offset in the direction of movement of the moving member. The position detection device according to claim 1.

6. The plurality of detection coils include a first detection coil and a second detection coil, The detectable range of the first detection coil and the detectable range of the second detection coil overlap in part and are continuous in the direction of movement. The position detection device according to claim 5.

7. As the moving member moves from one end to the other in the direction of movement, the first detection coil and the second detection coil each face a plurality of recesses that are spaced apart in the direction of movement. The position detection device according to claim 6.

8. As the moving member moves from one moving end to the other moving end, the lengths of the multiple recesses facing the first detection coil are different in the direction of movement. As the moving member moves from one moving end to the other moving end, the lengths of the multiple recesses facing the second detection coil are different in the direction of movement. The position detection device according to claim 7.

9. The recess is formed by penetrating the conductive detection member in a direction away from the excitation coil and the detection coil. The position detection device according to claim 1.

10. A steering device for a vehicle comprising a shaft that moves axially forward and backward along the width direction of the vehicle, a housing that houses the shaft, and a position detection device that detects the position of the shaft relative to the housing, wherein the wheels are steered as the shaft moves axially, The position detection device is, An conductive detection member attached to the shaft, It comprises an excitation coil and a detection coil that are arranged extending in the direction of movement of the shaft and facing the conductive detection member, The conductive detection member has a recess formed in the direction away from the excitation coil and the detection coil, The magnetic field generated by the excitation coil induces a current flowing through the conductive detection member, which in turn induces a voltage in the detection coil. The magnitude of the voltage induced in the detection coil changes depending on the position of the recess relative to the detection coil. Steering device for vehicles.

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