Position detection device

Abstract

To provide a position detector which can be reduced in size and weight.SOLUTION: A stroke sensor 1 comprises: an excitation coil 33 that is located extending in the movement direction of a rack shaft 13; detection coils 31, 32 that output voltages corresponding to the positions of sections 21, 22 of a target 2 that are to be detected, the target moving together with the rack shaft 13 in a prescribed detection range in the movement direction of the rack shaft 13 by a magnetic field which the excitation coil 33 generates; and a computation unit 40 that calculates by computation the position of the rack shaft 13 from the output voltages of the detection coils 31, 32. The detection coils 31, 32 include main coil parts 313, 323 that generate voltages corresponding to the positions of the sections 21, 22 to be detected, by the magnetic field that the excitation coil 33 generates when the positions of the sections 21, 22 to be detected are within a detection range, and sub-coil parts 314, 324 that generate voltages by the magnetic field that the excitation coil 33 generates when the positions of the sections 21, 22 to be detected are outside of the detection range.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a position detection device that detects the position of a moving member that moves forward and backward in a predetermined moving direction.

Background Art

[0002] Conventionally, position detection devices that detect the position of a moving member that moves forward and backward in a predetermined moving direction have been used in various fields such as industrial machines and automobiles.

[0003] The electromagnetic induction linear scale described in Patent Document 1 includes a coil array composed of a predetermined number of coil elements excited by a first AC signal, a magnetic member that relatively displaces along its axis outside the coil array, and a detection unit that detects the position of the magnetic member with respect to the coil array from the output voltage of each coil element. The magnetic member changes the amplitude of the output voltage of the coil element according to the positional relationship with the coil element. The detection unit absolutely detects the relative position of the magnetic member with respect to the coil array from the phase difference between the second AC signal obtained by synthesizing the differential outputs between the coil elements and the first AC signal.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the electromagnetic induction linear scale described in Patent Document 1, a large number of coil elements must be arranged side by side over the entire movement range of the magnetic member, resulting in an increase in installation size and weight. Therefore, an object of the present invention is to provide a position detection device that can be miniaturized and lightened.

Means for Solving the Problems

[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: an excitation coil arranged along the moving member and extending in the direction of movement; a detection coil that outputs a voltage corresponding to the position of a part to be detected that moves together with the moving member within a predetermined detection range in the direction of movement, using a magnetic field generated by the excitation coil; and a calculation unit that calculates the position of the moving member using the output voltage of the detection coil, wherein the detection coil has a pair of coil elements whose output voltage changes according to the position of the moving member, the phases of the output voltages of the pair of coil elements are different from each other when the moving member moves within the detection range, and at least one of the pair of coil elements is a main coil section that generates a voltage corresponding to the position of the part to be detected by the magnetic field generated by the excitation coil when the position of the part to be detected is within the detection range, and when the position of the part to be detected is outside the detection range, the magnetic field generated by the excitation coil Predetermined voltage It has a sub-coil section that generates When the position of the detected part is outside the detection range, the voltage induced in the main coil is approximately zero, and when the position of the detected part is within the detection range, no voltage is induced in the sub-coil. Each of the pair of coil elements, excluding the sub-coil, has a shape formed by combining two sinusoidal conductor wires whose shape, when viewed from a direction perpendicular to the direction of movement, is symmetrical across a symmetry axis parallel to the direction of movement, and of the pair of coil elements, the coil element with a larger distance between the conductor wires at the end of the detection coil has the sub-coil at that end. A position detection device is provided. Furthermore, the present invention relates to a position detection device for detecting the position of a moving member that moves back and forth in a predetermined direction of movement, comprising: an excitation coil arranged along the moving member and extending in the direction of movement; a plurality of detection coils that output a voltage corresponding to the position of a part to be detected that moves together with the moving member within a predetermined detection range in the direction of movement, based on the magnetic field generated by the excitation coil; and a calculation unit that calculates the position of the moving member based on the output voltages of the plurality of detection coils, wherein the plurality of detection coils are arranged in a direction perpendicular to the extending direction of the excitation coil, the plurality of parts to be detected are arranged at different positions in the direction of movement corresponding to each of the plurality of detection coils, the detection range of each of the plurality of detection coils is offset in the direction of movement of the moving member, and each of the plurality of detection coils comprises a pair of coil elements whose output voltage changes according to the position of the moving member. The present invention provides a position detection device in which, when the moving member moves within the detection range of the detection coil, the phases of the output voltages of the pair of coil elements are different from each other, and in each of the plurality of detection coils, at least one of the pair of coil elements has a main coil section that generates a voltage corresponding to the position of the detected part when the position of the detected part corresponding to the detection coil is within the detection range of the detection coil by the magnetic field generated by the excitation coil, and a sub-coil section that generates a predetermined voltage when the position of the detected part is outside the detection range of the detection coil, wherein the voltage induced in the main coil section is approximately zero when the position of the detected part is outside the detection range of the detection coil, and no voltage is induced in the sub-coil section when the position of the detected part is within the detection range of the detection coil. [Effects of the Invention]

[0007] According to the present invention, it is possible to miniaturize and lighten the position detection device. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of a vehicle equipped with a steer-by-wire steering system that includes a stroke sensor as a position detection device according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view along line AA in Figure 1. [Figure 3] This is a perspective view showing the target, substrate, CPU, case components, rack shaft, and part of the housing. [Figure 4] (a) is an overall view of the wiring patterns formed on the first to fourth metal layers of the substrate, seen through the material. (b) and (c) are magnified views of (a). [Figure 5] (a) to (d) are plan views showing the first to fourth metal layers, respectively. [Figure 6] 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 first sinusoidal coil element and the first cosine-shaped coil element of the first detection coil. [Figure 7] (a) is an explanatory diagram showing the relationship between the peak voltage, which is the peak value of the induced voltage induced in the first sinusoidal coil element, and the position of the first target. (b) is an explanatory diagram showing the relationship between the peak voltage, which is the peak value of the induced voltage induced in the first cosine coil element, and the position of the second target. [Figure 8] (a) to (c) are explanatory diagrams showing the relative positional relationship between the first and second detection coils and the first and second targets. [Figure 9] This is a schematic diagram showing the dimensional relationship between the first and second detection coils and excitation coils on the substrate and the first and second targets. [Figure 10] This flowchart shows an example of the calculation process that the CPU performs to determine the position of the rack shaft. [Figure 11] This is a configuration diagram showing the configuration of the substrate and the first and second targets related to a modified example. [Modes for carrying out the invention]

[0009] [Embodiment] Figure 1 is a schematic diagram of a vehicle equipped with a steer-by-wire steering system 10 that includes a stroke sensor 1 as a position detection device according to an embodiment of the present invention. In Figure 1, the steering system 10 is shown as viewed from the rear side in the longitudinal direction of the vehicle, with the right side of the drawing corresponding to the right side in the vehicle width direction and the left side of the drawing corresponding to the left side in the vehicle width direction. In the following explanation referring to the drawings, the terms "right" and "left" may be used, but these expressions are used for the convenience of explanation and do not limit the direction of the stroke sensor 1 in actual use.

[0010] As shown in Figure 1, the steering device 10 includes a stroke sensor 1, tie rods 12 connected to the steering wheels 11 (left and right front wheels), a rack shaft 13 connected to the tie rods 12, a cylindrical housing 14 that houses the rack shaft 13, a worm reduction mechanism 15 having a pinion gear 151 that meshes with the rack teeth 131 of the rack shaft 13, an electric motor 16 that applies a moving force in the vehicle width direction to the rack shaft 13 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.

[0011] The rack shaft 13 is a movable member whose position relative to the housing 14 is detected by the stroke sensor 1. The direction of movement of the rack shaft 13 is the axial direction parallel to the central axis of the rack shaft 13.

[0012] In Figure 1, the housing 14 is shown by a dashed line. The rack shaft 13 is supported by a pair of rack bushings 141 attached to both ends of the housing 14. 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.

[0013] The electric motor 16 generates torque from the motor current supplied by the steering control device 19, and rotates the worm wheel 152 and pinion gear 151 via the worm gear 153. When the pinion gear 151 rotates, the rack shaft 13 moves linearly back and forth along the vehicle width direction, and the left and right steering wheels 11 are steered. The rack shaft 13 is movable to the right and left in the vehicle width direction within a predetermined range from the neutral position when the steering angle is zero.

[0014] In Figure 1, the stroke range R, which corresponds to the maximum travel distance of the rack shaft 13 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 1 can detect the absolute position of the rack shaft 13 relative to the housing 14 throughout this stroke range R.

[0015] (Configuration of stroke sensor 1) The stroke sensor 1 comprises a target 2, which is a conductive member attached to the rack shaft 13; a circuit board 3 positioned opposite the target 2; a calculation unit 40 consisting of a CPU (processing unit) 4 mounted on the circuit board 3; a case member 5 having a connector 50; a power supply unit 6 that generates a high-frequency voltage; and a cable 7 for connecting the connector 50 attached to the case member 5 to the power supply unit 6 and the steering control device 19. The circuit board 3 is housed in the case member 5, positioned parallel to the rack shaft 13, and fixed immovably to the housing 14.

[0016] The stroke sensor 1 detects the axial (direction of movement) position of the rack shaft 13 relative to the housing 14 and outputs the detected position information to the steering control device 19 via the cable 7. The steering control device 19 controls the electric motor 16 so that the position of the rack shaft 13 detected by the stroke sensor 1 corresponds to the steering angle of the steering wheel 17 detected by the steering angle sensor 18.

[0017] Figure 2 is a cross-sectional view taken along line AA in Figure 1. Figure 3 is a perspective view showing part of the target 2, substrate 3, CPU 4, case member 5, rack shaft 13, and housing 14.

[0018] The rack shaft 13 is a rod-shaped body made of steel, such as carbon steel for machine structures. The housing 14 is made of a cylindrical aluminum alloy, such as die-cast aluminum alloy. The housing 14 has an opening 140 that opens upward in the vertical direction, and a case member 5 is attached to close this opening 140.

[0019] Target 2 integrally comprises two detectable portions 21 and 22 for detecting the position of the rack shaft 13, and a linear portion 23 extending parallel to the axial direction of the rack shaft 13. In other words, in this embodiment, the two detectable portions 21 and 22 are formed by Target 2. The two detectable portions 21 and 22 are located at different axial positions along the central axis C of the rack shaft 13. The linear portion 23 connects the two detectable portions 21 and 22. The material of Target 2 is preferably highly conductive, and for example, aluminum alloys or copper alloys can be suitably used.

[0020] Target 2 is mounted on the rack shaft 13, and its two detection parts 21 and 22 and linear part 23 move together with the rack shaft 13. The rack shaft 13 has a flat mounting surface 13a for mounting Target 2, and Target 2 is fixed to the mounting surface 13a, for example, by welding. Alternatively, the detection parts may be formed by machining the shaft material of the rack shaft 13.

[0021] The case member 5 has a case body 51 and a case lid 52. The case body 51 is provided with a plurality of fixing parts 510 for fixing to the housing 14, and these fixing parts 510 are fixed to fixing parts 142 provided on the housing 14 by bolts 500 (see Figure 2). A packing 53 is placed between the case body 51 and the housing 14 to prevent moisture from entering through the opening 140 of the housing 14. The case body 51 and the case lid 52 are made of, for example, an insulating resin material, but one or both of the case body 51 and the case lid 52 may be conductors.

[0022] The case body 51 has a bottom plate 511 facing the front surface 3a of the circuit board 3, and a peripheral side wall 512 provided around the bottom plate 511. The circuit board 3 is positioned between the bottom plate 511 of the case body 51 and the case lid 52. The case lid 52 is fixed to the open end of the peripheral side wall 512, for example, by adhesive. A connector 50 is attached to the case lid 52.

[0023] 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 in which the direction of movement of the rack shaft 13 is in the direction of the longer side (longitudinal direction). Note that the substrate 3 is not limited to a rigid substrate, but may also be a flexible substrate.

[0024] Figure 4(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. Figures 4(b) and (c) are enlarged sections of Figure 4(a). Figures 5(a) to (d) are plan views showing the first to fourth metal layers 301 to 304, respectively, as seen from the back surface 3b.

[0025] In Figures 4(a)-(c) and 5(a)-(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. Note that the wiring patterns shown in Figures 4(a)-(c) and 5(a)-(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.

[0026] The substrate 3 has multiple through-holes 300 (see Figure 3) for connecting the terminals of the connector 50, and first to sixth vias 351 to 356 for inter-layer connection of the wiring patterns of each layer. A CPU 4 is mounted on the back surface 3b of the substrate 3. The CPU 4 has an arithmetic processing function that executes calculations according to a program, and an AD conversion (analog-to-digital conversion) function.

[0027] The substrate 3 has first and second detection coils 31 and 32 formed thereon for detecting the position of target 2. Additionally, the substrate 3 has an excitation coil 33 formed thereon, extending axially along the rack shaft 13 and surrounding the first and second detection coils 31 and 32. The first and second detection coils 31 and 32 output a voltage corresponding to the position of the detected parts 21 and 22 of target 2 within a predetermined detection range in the direction of movement of the rack shaft 13, based on the magnetic field generated by the excitation coil 33. The first and second detection coils 31 and 32 are aligned perpendicular to the direction of extension of the excitation coil 33 (axial direction of the rack shaft 13). The CPU 4 calculates the position of the rack shaft 13 based on the output voltages of the first and second detection coils 31 and 32.

[0028] The first metal layer 301 has first and second curved sections 301a and 301b, a first connection section 301c that connects one end of the first curved section 301a to a terminal of the CPU 4, a second connection section 301d that connects one end of the second curved section 301b to a terminal of the CPU 4, a first short-circuit section 301e that connects the first via 351 and the third via 353, and a second short-circuit section 301f that connects the fourth via 354 and the sixth via 356.

[0029] The second metal layer 302 has first and second curved portions 302a and 302b, a first connection portion 302c that connects one end of the first curved portion 302a to the terminals of the CPU 4, a second connection portion 302d that connects one end of the second curved portion 302b to the terminals of the CPU 4, and a protruding portion 302e that extends from the other end of the second curved portion 302b toward the first curved portion 302a in the short-side direction of the substrate 3.

[0030] The third metal layer 303 has first and second curved portions 303a and 303b, a first connection portion 303c that connects one end of the first curved portion 303a to a terminal of the CPU 4, and a second connection portion 303d that connects one end of the second curved portion 303b to a terminal of the CPU 4.

[0031] The fourth metal layer 304 has first and second curved portions 304a and 304b, a first connection portion 304c that connects one end of the first curved portion 304a to the terminals of the CPU 4, a second connection portion 304d that connects one end of the second curved portion 304b to the terminals of the CPU 4, and a protruding portion 304e that extends from one end of the first curved portion 304a toward the second curved portion 304b in the short-side direction of the substrate 3.

[0032] The first curved portion 301a of the first metal layer 301 and the first curved portion 303a of the third metal layer 303 are connected at their other ends by a second via 352. Furthermore, the second curved portion 301b of the first metal layer 301 and the second curved portion 303b of the third metal layer 303 are connected at their other ends by a fifth via 355.

[0033] The first curved portion 302a of the second metal layer 302 and the first curved portion 304a of the fourth metal layer 304 are connected at their other ends by the first via 351, the third via 353, and the first short-circuit portion 301e of the first metal layer 301. The second curved portion 302b of the second metal layer 302 and the second curved portion 304b of the fourth metal layer 304 are connected at their other ends by the fourth via 354, the sixth via 356, and the second short-circuit portion 301f of the first metal layer 301.

[0034] The first and second curved portions 301a, 301b of the first metal layer 301, the first and second curved portions 302a, 302b of the second metal layer 302, the first and second curved portions 303a, 303b of the third metal layer 303, and the first and second curved portions 304a, 304b of the fourth metal layer 304 are curved in a sinusoidal shape.

[0035] The first curved portion 301a of the first metal layer 301, the first curved portion 303a of the third metal layer 303, the first curved portion 302a of the second metal layer 302, and the first curved portion 304a of the fourth metal layer 304 are symmetrical in the short-side direction of the substrate 3 across the first axis of symmetry A1 shown in Figure 4(a). Furthermore, the second curved portion 301b of the first metal layer 301, the second curved portion 303b of the third metal layer 303, the second curved portion 302b of the second metal layer 302, and the second curved portion 304b of the fourth metal layer 304 are symmetrical in the short-side direction of the substrate 3 across the second axis of symmetry A2 shown in Figure 4(a). The first axis of symmetry A1 and the second axis of symmetry A2 are parallel to each other and parallel to the axial direction of the rack shaft 13.

[0036] The first detection coil 31 includes a first sinusoidal coil element 311 consisting of a first curved portion 301a of the first metal layer 301 and a first curved portion 303a of the third metal layer 303, and a first cosine wave coil element 312 consisting of a first curved portion 302a and a first short-circuit portion 301e of the second metal layer 302, and a first curved portion 304a and an overhang portion 304e of the fourth metal layer 304. In other words, each of the first sinusoidal coil element 311 and the first cosine-shaped coil element 312, excluding the protruding portion 304e, has a shape when viewed from a direction perpendicular to the axial direction of the rack shaft 13 that is a combination of two sinusoidal curved conductor wires (first curved portion 301a and first curved portion 303a, and first curved portion 302a and first curved portion 304a) that are symmetrical with respect to the first axis of symmetry A1.

[0037] The second detection coil 32 includes a second sinusoidal coil element 321 consisting of the second curved portion 301b of the first metal layer 301 and the second curved portion 303b of the third metal layer 303, and a second cosine-shaped coil element 322 consisting of the second curved portion 302b and protruding portion 302e of the second metal layer 302, the second curved portion 304b of the fourth metal layer 304, and the second short-circuit portion 301f of the first metal layer 301. In other words, each of the second sinusoidal coil element 321 and the second cosine-shaped coil element 322, excluding the protruding portion 302e, has a shape when viewed from a direction perpendicular to the axial direction of the rack shaft 13 that is a combination of two sinusoidal curved conductor wires (the second curved portion 301b and the second curved portion 303b, and the second curved portion 302b and the second curved portion 304b) that are symmetrical with respect to the second axis of symmetry A2.

[0038] The excitation coil 33 is rectangular in shape, having a pair of long sides 331, 332 extending in the axial direction of the rack shaft 13, and a pair of short sides 333, 334 between the pair of long sides 331, 332. In this embodiment, the long sides 331, 332 and the short sides 333, 334 are formed as a wiring pattern on the first metal layer 301.

[0039] Of the pair of short sides 333 and 334, the short side 333 on the connector 50 side consists of two straight sections 333a and 333b that sandwich the first and second connecting parts 301c and 301d of the first metal layer 301, the first and second connecting parts 302c and 302d of the second metal layer 302, the first and second connecting parts 303c and 303d of the third metal layer 303, and the first and second connecting parts 304c and 304d of the fourth metal layer 304. The ends of these two straight sections 333a and 333b are connected to the through-hole 300 by connector connecting parts 301g and 301h formed in the first metal layer 301.

[0040] The excitation coil 33 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. Furthermore, the excitation coil may be formed separately from the substrate 3. In this embodiment, the excitation coil 33 makes one orbit around the first and second detection coils 31 and 32, but the excitation coil may be formed to make multiple orbits around the first and second detection coils 31 and 32.

[0041] Of the two detectable parts 21 and 22 of target 2, one detectable part 21 is provided in correspondence with the first detection coil 31, and the other detectable part 22 is provided in correspondence with the second detection coil 32. Hereinafter, the detectable part 21 corresponding to the first detection coil 31 will be referred to as the first detectable part 21, and the other detectable part 22 corresponding to the second detection coil 32 will be referred to as the second detectable part 22.

[0042] When the direction perpendicular to the front surface 3a and back surface 3b of the substrate 3 is defined as the substrate perpendicular direction, the first detected portion 21 is positioned so as to be aligned with the first detection coil 31 in the substrate perpendicular direction, but not so as to be aligned with the second detection coil 32 in the substrate perpendicular direction. The second detected portion 22 is positioned so as to be aligned with the second detection coil 32 in the substrate perpendicular direction, but not so as to be aligned with the first detection coil 31 in the substrate perpendicular direction. The linear portion 23 is provided between the first detected portion 21 and the second detected portion 22 in the longitudinal and transverse directions of the substrate 3, and is positioned so as not to be aligned with the first detection coil 31 and the second detection coil 32 in the substrate perpendicular direction, but to be aligned with the protruding portion 302e of the second metal layer 302 and the protruding portion 304e of the fourth metal layer 304 in the substrate perpendicular direction.

[0043] A sinusoidal alternating current is supplied to the excitation coil 33 from the power supply unit 6. Induced voltages are generated in the first sinusoidal coil element 311 and the first cosine wave coil element 312 of the first detection coil 31, and in the second sinusoidal coil element 321 and the second cosine wave coil element 322 of the second detection coil 32, due to the linking of the magnetic flux of the magnetic field generated by the excitation coil 33. Eddy currents are also generated in the target 2 by the magnetic field generated by the excitation coil 33. These eddy currents act to cancel out the magnetic field in the portion of the substrate 3 aligned perpendicular to the target 2, so that the magnetic field strength in the portion of the first detection coil 31 aligned perpendicular to the first detected part 21 becomes weaker than the magnetic field strength in other portions, and the magnetic field strength in the portion of the second detection coil 32 aligned perpendicular to the second detected part 22 becomes weaker than the magnetic field strength in other portions.

[0044] The first cosine wave shaped coil element 312 has a first main coil portion 313 consisting of a first curved portion 302a of the second metal layer 302, a first curved portion 304a of the fourth metal layer 304, and a first short-circuit portion 301e of the first metal layer 301, and a first sub-coil portion 314 consisting of an overhanging portion 304e of the fourth metal layer 304. The first main coil portion 313 generates a voltage corresponding to the position of the first detected portion 21 by the magnetic field generated by the excitation coil 33 when the first detected portion 21 is aligned perpendicularly to the substrate with the first detection coil 31. The first sub-coil portion 314 generates a predetermined voltage by the magnetic field generated by the excitation coil 33 when the first detected portion 21 is not aligned perpendicularly to the substrate with the first detection coil 31.

[0045] The second cosine wave shaped coil element 322 has a second main coil portion 323 consisting of the second curved portion 302b of the second metal layer 302, the second curved portion 304b of the fourth metal layer 304, and the second short-circuit portion 301f of the first metal layer 301, and a second sub-coil portion 324 consisting of the protruding portion 302e of the second metal layer 302. The second main coil portion 323 generates a voltage corresponding to the position of the second detected portion 22 by the magnetic field generated by the excitation coil 33 when the second detected portion 22 is aligned perpendicular to the substrate with the second detection coil 32. The second sub-coil portion 324 generates a predetermined voltage by the magnetic field generated by the excitation coil 33 when the second detected portion 22 is not aligned perpendicular to the substrate with the second detection coil 32.

[0046] The first sub-coil section 314 (the protruding portion 304e of the fourth metal layer 304) has, as shown in Figure 4(b), a loop-shaped electromotive force section 314a and a pair of connecting wire sections 314b and 314c that connect the electromotive force section 314a to the first curved portion 304a and the first connecting portion 304c of the fourth metal layer 304. The electromotive force section 314a is formed in a rectangular shape and generates a voltage by the magnetic flux of the magnetic field linked inside the electromotive force section 314a. The pair of connecting wire sections 314b and 314c extend parallel to each other along the short-side direction of the substrate 3.

[0047] Of the pair of connecting wires 314b and 314c of the first sub-coil section 314, one connecting wire 314b connects one end of the electromotive force section 314a to the first curved section 304a, and the other connecting wire 314c connects the other end of the electromotive force section 314a to the first connecting wire 304c. In other words, the first sub-coil section 314 is interposed between the first curved section 304a and the first connecting wire 304c. The voltage generated in the electromotive force section 314a is output to the CPU 4 as the voltage of the first cosine wave shaped coil element 312.

[0048] The second sub-coil section 324 (the protruding portion 302e of the second metal layer 302) has, as shown in Figure 4(c), a loop-shaped electromotive force section 324a and a pair of connecting wire sections 324b and 324c that connect the electromotive force section 324a to the second curved portion 302b of the second metal layer 302 and the fourth via 354. The electromotive force section 324a is formed in a rectangular shape and generates a voltage by the magnetic flux of the magnetic field linked inside the electromotive force section 324a. The pair of connecting wire sections 324b and 324c extend parallel to each other along the short-side direction of the substrate 3.

[0049] Of the pair of connecting wires 324b and 324c of the second sub-coil section 324, one connecting wire 324b connects one end of the electromotive force section 324a to the second curved section 302b, and the other connecting wire 324b connects the other end of the electromotive force section 324a to the fourth via 354. In other words, the second sub-coil section 324 is interposed between the second curved section 302b and the second short-circuit wire section 301f. The voltage generated in the electromotive force section 324a is output to the CPU 4 as the voltage of the second cosine wave shaped coil element 322.

[0050] The first sub-coil section 314 and the second sub-coil section 324 are aligned in the longitudinal direction of the substrate 3 between the first main coil section 313 and the second main coil section 323. When the rack shaft 13 moves, the linear section 23 of the target 2 is aligned perpendicular to the substrate with the first sub-coil section 314 while the first detected section 21 is aligned perpendicular to the substrate with the first detection coil 31, and aligned perpendicular to the substrate with the second sub-coil section 324 while the second detected section 22 is aligned perpendicular to the substrate with the second detection coil 32.

[0051] The voltages of the first sub-coil section 314 and the second sub-coil section 324 are used in a selection process in the calculation processing of the CPU 4, described later, to select whether to determine the position of the rack shaft 13 using the position of the first detected part 21 determined by the output voltage of the first detection coil 31, or to determine the position of the rack shaft 13 using the position of the second detected part 22 determined by the output voltage of the second detection coil 32.

[0052] Furthermore, the first sinusoidal coil element 311 may be provided with a first sub-coil section that generates a predetermined voltage by the magnetic field generated by the excitation coil 33 when the first detected part 21 is not aligned perpendicularly to the substrate with the first detection coil 31. Also, the second sinusoidal coil element 321 may be provided with a second sub-coil section that generates a predetermined voltage by the magnetic field generated by the excitation coil 33 when the second detected part 22 is not aligned perpendicularly to the substrate with the second detection coil 32. In other words, it is sufficient that at least one of the first sinusoidal coil element 311 and the first cosine wave coil element 312 has the first sub-coil section, and at least one of the second sinusoidal coil element 321 and the second cosine wave coil element 322 has the second sub-coil section.

[0053] However, by providing a first sub-coil section 314 to the first cosine wave shaped coil element 312, where the distance between the two sinusoidal conductor wires is large at the end of the first detection coil 31, and by providing a second sub-coil section 324 to the second cosine wave shaped coil element 322, where the distance between the two sinusoidal conductor wires is large at the end of the second detection coil 32, the space on the substrate 3 can be effectively utilized, and the substrate 3 can be miniaturized.

[0054] When the first detected unit 21 is aligned perpendicularly to the substrate with respect to the first detection coil 31, the peak voltage values ​​induced in the first sinusoidal coil element 311 and the first cosine wave coil element 312 (first main coil section 313) change depending on the position of the first detected unit 21 relative to the substrate 3. Similarly, when the second detected unit 22 is aligned perpendicularly to the substrate with respect to the second detection coil 32, the peak voltage values ​​induced in the second sinusoidal coil element 321 and the second cosine wave coil element 322 (second main coil section 323) change depending on the position of the second detected unit 22 relative to the substrate 3. Here, the peak voltage value refers to the maximum absolute value of the voltage within one cycle of the alternating current supplied to the excitation coil 33.

[0055] As the first detected unit 21 moves from one end to the other of the first detection coil 31, the phases of the peak voltage values ​​induced in the first sinusoidal coil element 311 and the first cosine wave coil element 312 are different from each other. Similarly, as the second detected unit 22 moves from one end to the other of the second detection coil 32, the phases of the peak voltage values ​​induced in the second sinusoidal coil element 321 and the second cosine wave coil element 322 are also different from each other.

[0056] In this embodiment, the phase difference between the peak voltage values ​​induced in the first sinusoidal coil element 311 and the first cosine wave coil element 312 of the first detection coil 31, and the phase difference between the peak voltage values ​​induced in the second sinusoidal coil element 321 and the second cosine wave coil element 322 of the second detection coil 32, are both 90°. The voltages induced in the first sinusoidal coil element 311 and the first cosine wave coil element 312 of the first detection coil 31, and the voltages induced in the second sinusoidal coil element 321 and the second cosine wave coil element 322 of the second detection coil 32, are output to the CPU 4 as output voltages.

[0057] As shown in Figure 4(a), first and second buffer regions E1 and E2 are provided between each of the pair of short sides 333 and 334 of the excitation coil 33 and the first detection coil 31 and the second detection coil 32, respectively, to suppress the voltage induced in the first sinusoidal coil element 311, the first cosine wave-shaped coil element 312, the second sinusoidal coil element 321, and the second cosine wave-shaped coil element 322 by the magnetic flux generated by the current flowing through the pair of short sides 333 and 334.

[0058] Furthermore, in order to suppress the induced voltage generated when the first detected portion 21 or the second detected portion 22 is located in a position aligned perpendicularly to the substrate with the first buffer region E1, in the first buffer region E1, the first connector connection portions 301c, 302c, 303c, and 304c of the first to fourth metal layers 301 to 304 overlap in the thickness direction of the substrate 3, and the second connector connection portions 301d, 302d, 303d, and 304d of the first to fourth metal layers 301 to 304 overlap in the thickness direction of the substrate 3.

[0059] Figure 6 shows the supply voltage V0 supplied from the power supply unit 6 to the excitation coil 33 and the induced voltage V induced in the first sinusoidal coil element 311 of the first detection coil 31. S1 and the induced voltage V induced in the first cosine wave shaped coil element 312 C1 This graph shows an example of the relationship. In the graph in Figure 6, the horizontal axis is the time axis, and the left and right vertical axes are the supply voltage V0 and the induced voltage V0. S1 ,V C1 This shows that the excitation coil 33 is supplied with a high-frequency AC voltage of, for example, about 1 MHz as the supply voltage V0.

[0060] In the example shown in Figure 6, the supply voltage V0 and the induced voltage V S1 ,V C1 Although they are in phase, the induced voltage V is generated in the first sinusoidal coil element 311. S1When the first detection unit 21 passes through a position corresponding to the intersection of the first curved portion 301a of the first metal layer 301 and the first curved portion 303a of the third metal layer 303 as viewed from the direction perpendicular to the substrate, the in-phase and anti-phase states are switched. Also, the induced voltage V induced in the first cosine-wave-shaped coil element 312 C1 When the first detection unit 21 passes through a position corresponding to the intersection of the first curved portion 302a of the second metal layer 302 and the first curved portion 304a of the fourth metal layer 304 as viewed from the direction perpendicular to the substrate, the in-phase and anti-phase states are switched.

[0061] FIG. 7(a) is an explanatory diagram schematically showing the relationship between the peak voltage V S1 which is the peak value of the induced voltage induced in the first sine-wave-shaped coil element 311 and the position of the first detection unit 21. FIG. 7(b) is an explanatory diagram schematically showing the relationship between the peak voltage V which is the peak value of the induced voltage induced in the first cosine-wave-shaped coil element 312 and the position of the first detection unit 21. C1 which is the peak value of the induced voltage induced in the first cosine-wave-shaped coil element 312 and the position of the first detection unit 21. のピーク値であるピーク電圧V SP1 と、第1の被検出部21の位置との関係を模式的に示す説明図である。図7(b)は、第1の余弦波形状コイル要素312に誘起される誘起電圧V C1 のピーク値であるピーク電圧V CP1 と、第1の被検出部21の位置との関係を模式的に示す説明図である。

[0062] In the graphs of the peak voltages V SP1 , V CP1 shown in FIGS. 7(a) and (b), the position of the center of the first detection unit 21 is shown on the horizontal axis. P1 on the horizontal axis indicates the position of the center of the first detection unit 21 when the left end of the first detection unit 21 coincides with the left ends of the first sine-wave-shaped coil element 311 and the first cosine-wave-shaped coil element 312, and P2 on the horizontal axis indicates the position of the center of the first detection unit 21 when the right end of the first detection unit 21 coincides with the right ends of the first sine-wave-shaped coil element 311 and the first cosine-wave-shaped coil element 312. In FIGS. 7(a) and (b), the first detection unit 21 at the position of P1 is indicated by a dashed line, and the first detection unit 21 at the position of P2 is indicated by a dotted-dashed line.

[0063] The output voltage of the first sinusoidal coil element 311 and the first cosine-shaped coil element 312 changes according to the position of the rack shaft 13 based on the difference between the magnetic field strength in the portion facing the first detected portion 21 in the direction perpendicular to the substrate and the magnetic field strength in the portion not facing the first detected portion 21.

[0064] In the graph shown in Figure 7(a), the peak voltage V SP1 This is the induced voltage V induced in the first sinusoidal coil element 311. S1 A positive value is defined as the time when the voltage supplied to the excitation coil 33 is in phase with the supply voltage V0, and a negative value is defined as the time when it is out of phase. Similarly, in the graph shown in Figure 7(b), the peak voltage V CP1 This is the induced voltage V induced in the first cosine wave shaped coil element 312. C1 A positive value is defined as the voltage being in phase with the supply voltage V0 supplied to the excitation coil 33, and a negative value is defined as the voltage being out of phase.

[0065] When the rack shaft 13 moves at a constant speed in one direction, the peak voltage V is as shown in Figures 7(a) and (b) while the entire first detected portion 21 in the axial direction of the rack shaft 13 overlaps with the first sinusoidal coil element 311 and the first cosine wave coil element 312 (first main coil portion 313) in the direction perpendicular to the substrate. SP1 The waveform changes sinusoidally, and the peak voltage V CP1 The voltage changes in a cosine wave pattern. Therefore, the CPU 4 can calculate the position of the rack shaft 13 based on the output voltages of the first sinusoidal coil element 311 and the first cosine wave coil element 312.

[0066] Similarly, with respect to the second detection coil 32, when the rack shaft 13 moves at a constant speed in one direction, while the entire second detection portion 22 in the axial direction of the rack shaft 13 overlaps with the second sinusoidal coil element 321 and the second cosine wave coil element 322 (second main coil portion 323) in the direction perpendicular to the substrate, an induced voltage V is induced in the second sinusoidal coil element 321. S2 The peak value is the peak voltage V SP2As the waveform changes sinusoidally, an induced voltage V is generated in the second cosine-shaped coil element 322. C2 The peak value is the peak voltage V CP2 The output voltage changes in a cosine wave pattern. Therefore, the CPU 4 can calculate the position of the rack shaft 13 based on the output voltages of the second sinusoidal coil element 321 and the second cosine wave coil element 322. Details of how the CPU 4 calculates the position of the rack shaft 13 will be described later.

[0067] Figures 8(a) to 8(c) are explanatory diagrams showing the relative positional relationship between the first and second detection coils 31, 32 and the first and second detection units 21, 22 in the direction perpendicular to the substrate. In Figures 8(a) to 8(c), the substrate 30 is viewed through from the back surface 3b side of the substrate 3, and the first and second detection coils 31, 32 and excitation coil 33, the rack shaft 13 and target 2 are shown superimposed in the direction perpendicular to the substrate.

[0068] Furthermore, in Figures 8(a) to (c), the center point C1 of the area on the substrate 3 where the first and second detection coils 31 and 32 are formed, and the center points C of the first and second detection parts 21 and 22, respectively. 21 ,C 22 , and center point C 21 ,C 22 This indicates the midpoint C2.

[0069] Figure 8(a) shows a state where the steering angle of the steering wheel 17 is zero, the rack shaft 13 is in the neutral position, and the center point C1 and the midpoint C2 coincide. In this state, the right end of the first detected part 21 coincides with the right end of the first detection coil 31, and the left end of the second detected part 22 coincides with the left end of the second detection coil 32.

[0070] Figure 8(b) shows a state in which the right end of the second detection unit 22 and the right end of the second detection coil 32 coincide. In this state, the axial distance of the rack shaft 13 between the center point C1 and the midpoint C2 is denoted as L1. This distance L1 is the detection range in which the position of the first detection unit 21 can be detected by the first detection coil 31.

[0071] Figure 8(c) shows a state in which the left end of the first detected part 21 coincides with the left end of the first detection coil 31. In this state, the axial distance of the rack shaft 13 between the center point C1 and the midpoint C2 is denoted as L2. This distance L2 is the detection range in which the position of the second detected part 22 can be detected by the second detection coil 32.

[0072] Thus, the detection range in which the position of the first detected part 21 can be detected by the first detection coil 31 and the detection range in which the position of the second detected part 22 can be detected by the second detection coil 32 are offset in the direction of movement of the rack shaft 13. Furthermore, at the neutral position of the rack shaft 13, the position of the first detected part 21 can be detected by the first detection coil 31, and the position of the second detected part 22 can be detected by the second detection coil 32. In other words, the detection range in which the position of the first detected part 21 can be detected by the first detection coil 31 and the detection range in which the position of the second detected part 22 can be detected by the second detection coil 32 overlap in part and are continuous in the direction of movement of the rack shaft 13.

[0073] The CPU4 can calculate the absolute position of the rack shaft 13 within an axial range of length L1 + L2, centered on the neutral position of the rack shaft 13. The length L1 + L2 is the same as, or longer than, the stroke range R of the rack shaft 13 (see Figure 1), and the stroke sensor 1 can detect the absolute position of the rack shaft 13 over the entire stroke range R.

[0074] Figure 9 is a schematic diagram showing the dimensional relationship between the first and second detection coils 31, 32 and excitation coil 33 on the substrate 3 and the first and second detected parts 21, 22. In Figure 9, the axial direction of the rack shaft 13 is defined as the x-axis direction, and the direction parallel to the substrate 3 and perpendicular to the x-axis direction is defined as the y-axis direction. In addition, in Figure 8, the dimensions of the first and second detection coils 31, 32 and excitation coil 33 in the y-axis direction are enlarged by a factor of two, and the distance between the first detection coil 31 and the second detection coil 32 is widened in the y-axis direction.

[0075] The origin of the x-axis is the center point C of the second detected part 22 in the state shown in Figure 8(c). 22 The position is such that the origin of the y-axis is the position of one of the longer sides 332 of the excitation coil 33. The coordinate point X1 on the x-axis is the center point C of the second detected part 22 in the state shown in Figure 8(a). 22 This indicates the position in the x-axis direction, and the coordinate point X2 on the x-axis is the center point C of the first detected unit 21 in the state shown in Figure 8(a). 21 This indicates the position in the x-axis direction. The coordinate point X3 on the x-axis is the center point C of the first detected unit 21 in the state shown in Figure 8(b). 21 This indicates the position in the x-axis direction. Also, coordinate point C2' is the center point C of the first and second detected parts 21 and 22 in the state shown in Figure 8(c). 21 ,C 22 The midpoint C2 is the coordinate point C2'', and the coordinate point C2'' is the center point C of the first and second detected units 21 and 22 in the state shown in Figure 8(b). 21 ,C 22 It is the midpoint C2.

[0076] In Figure 9, L is the x-axis length of the first and second detection coils 31 and 32. u is the ratio of the x-axis lengths of the first and second detected parts 21 and 22 to L. Δp1 is the distance from the left end of the first detection coil 31 to the center point C of the first detected part 21. 21 This is the distance in the x-axis direction from the left end of the second detection coil 32 to the center point C of the second detected part 22. Δp2 is the distance in the x-axis direction from the left end of the second detection coil 32 to the center point C of the second detected part 22. 22 This is the distance in the x-axis direction up to [the specified point].

[0077] When the first detected part 21 overlaps the first sinusoidal coil element 311 and the first cosine wave coil element 312 in the direction perpendicular to the substrate, Δp1 can be calculated by the following equation (1).

number

[0078] Furthermore, when the second detected part 22 overlaps the second sinusoidal coil element 321 and the second cosine wave coil element 322 in the direction perpendicular to the substrate, Δp2 can be calculated by the following equation (2).

number

[0079] Furthermore, tan -1 The calculation of the arctangent can be performed by, for example, referring to a sequence of numbers (lookup table) stored in a non-volatile memory element, thereby reducing the computational load.

[0080] Thus, CPU4 performs a division (V) with the output voltage of the first cosine wave-shaped coil element 312 as the denominator. SP1 / V CP1 Δp1 is calculated according to the result of ), and the output voltage of the second cosine wave coil element 322 is used as the denominator for division (V SP2 / V CP2 Δp2 is calculated according to the result of ). The CPU4 also performs division for the first detection coil 31 and the second detection coil 32, with the output voltages of the first cosine wave shaped coil element 312 and the second cosine wave shaped coil element 322 as the denominators, and determines the position of the rack shaft 13 based on the output voltage of the detection coil (first detection coil 31 or second detection coil 32) whose quotient has a larger absolute value.

[0081] The distance traveled by the rack shaft 13 in the x-axis direction for which the CPU 4 can determine the absolute position of the rack shaft 13 using equation (1), and the distance traveled by the rack shaft 13 in the x-axis direction for which the CPU 4 can determine the absolute position of the rack shaft 13 using equation (2), are both (1-u)L. Therefore, in this embodiment, the total distance traveled by the rack shaft 13 for which the CPU 4 can determine the absolute position of the rack shaft 13 is 2(1-u)L. Note that u is a value less than 0.5. A smaller value of u allows for detection of the absolute position of the rack shaft 13 over a longer distance, but if the value of u is too small, the error tends to be large. For this reason, it is desirable that the value of u be, for example, 0.01 or more and less than 0.5.

[0082] Figure 10 is a flowchart showing an example of the calculation process performed by the CPU 4 to determine the position P of the rack shaft 13. The CPU 4 executes the process shown in this flowchart at a predetermined calculation cycle and outputs the position P of the rack shaft 13 to the steering control device 19.

[0083] In this calculation process, CPU4 processes the peak voltage V SP1 ,V CP1 ,V SP2 ,V CP2 Calculate (Step S1), and the peak voltage V SP1 ,V CP1 Based on this, Δp1 is calculated using the above equation (1) (step S2), and the peak voltage V SP2 ,V CP2 Based on this, Δp2 is calculated using equation (2) above (step S3). Furthermore, in a selection process according to the relative magnitudes of the absolute values ​​of Δp1 and Δp2 (step S4), if the absolute value of Δp1 is the same as or greater than the absolute value of Δp2, the value of Δp1 is set as position P (step S5). If the absolute value of Δp2 is greater than the absolute value of Δp1, the value obtained by adding (1-u)L to the value of Δp2 is set as position P (step S6).

[0084] Note that the absolute value of Δp1 is (V SP1 / V CP1The larger the absolute value of ), the larger the value of Δp² is. SP2 / V CP2 The larger the absolute value of ), the larger the selection process in step S4 is (V SP1 / V CP1 The absolute value of the quotient, which is the result of the division by (V) and (V SP2 / V CP2 This is equivalent to comparing the absolute value of the quotient, which is the result of division by ), with the magnitude of the quotient.

[0085] Here, for example, as shown in Figure 8(b), if the first detected unit 21 is not aligned perpendicularly to the substrate with respect to the first detection coil 31, the voltage induced in the first sinusoidal coil element 311 and the first cosine wave coil element 312 (first main coil section 313) becomes approximately zero. If the first cosine wave coil element 312 does not have a first sub-coil section 314, then V CP1 Due to a slight error (V SP1 / V CP1 The absolute value of ) becomes extremely large, which can lead to making an incorrect selection in the selection process of step S4.

[0086] However, in this embodiment, when the first detected unit 21 is not aligned perpendicularly to the substrate with respect to the first detection coil 31, the voltage induced in the electromotive force portion 314a of the first sub-coil unit 314 causes V CP1 Since the value does not become approximately zero, the selection process in step S4 is performed appropriately. Furthermore, when the first detected unit 21 is aligned perpendicularly to the substrate with the first detection coil 31, no voltage is induced in the first sub-coil unit 314, and the first sub-coil unit 314 does not affect the calculation of Δp1. As a result, the position P of the rack shaft 13 can be calculated appropriately.

[0087] Furthermore, as shown in Figure 8(c), for example, even when the second detection unit 22 is not aligned perpendicularly to the substrate with the second detection coil 32, the voltage induced in the electromotive force portion 324a of the second sub-coil unit 324 will still produce V CP2 Since this value is not approximately zero, the selection process in step S4 can be performed appropriately, and the position P of the rack shaft 13 can be calculated appropriately.

[0088] As described above, according to this embodiment, by determining the position of the rack shaft 13 based on the output voltages of a first detection coil 31 having a first sub-coil portion 314 on a first cosine wave shaped coil element 312, and a second detection coil 32 having a second sub-coil portion 324 on a second cosine wave shaped coil element 322, it is possible to provide a stroke sensor 1 that is small, lightweight, and capable of accurately determining the position of the rack shaft 13.

[0089] [Differentiation] Figure 11 is a configuration diagram showing the configuration of the substrate 3A and the first and second targets 2A and 2B according to a modified example. The first and second targets 2A and 2B are conductive members attached to the rack shaft 13, and the substrate 3A is arranged inside the case member 5, similar to the embodiment described above. In Figure 11, components corresponding to those described with reference to Figure 4(a) for the first embodiment are given the same reference numerals as those used in Figure 4(a), and redundant explanations are omitted.

[0090] In the above embodiment, the case was described in which the target 2 has first and second detectable parts 21 and 22, and the linear part 23 is provided between the first detectable part 21 and the second detectable part 22. In this modified example, the first target 2A integrally has the first detectable part 21 and the first linear part 24, and the second target 2B integrally has the second detectable part 22 and the second linear part 25. The first linear part 24 and the second linear part 25 extend parallel to the axial direction of the rack shaft 13.

[0091] Furthermore, in the above embodiment, the case in which the first sub-coil portion 314 (the protruding portion 304e of the fourth metal layer 304) and the second sub-coil portion 324 (the protruding portion 302e of the second metal layer 302) are provided between the first main coil portion 313 and the second main coil portion 323 in the short-side direction of the substrate 3 was described. However, in this modified example, the first sub-coil portion 314 is provided between the first main coil portion 313 and the long side portion 331 of the excitation coil 33. The first sub-coil portion 314 consists of the protruding portion 302f of the second metal layer 302, and the protruding portion 302f is interposed between the first curved portion 302a and the first connecting portion 302c of the second metal layer 302 and is provided at the end of the first cosine wave shaped coil element 312.

[0092] The first linear portion 24 is aligned perpendicular to the substrate with the first sub-coil portion 314 while the first detected portion 21 is aligned perpendicular to the substrate with the first detection coil 31 when the rack shaft 13 is moving. The second linear portion 25 is aligned perpendicular to the substrate with the second sub-coil portion 324 while the second detected portion 22 is aligned perpendicular to the substrate with the second detection coil 32 when the rack shaft 13 is moving.

[0093] This modified version also provides the same effects as the embodiment described above.

[0094] (Summary of the embodiments) Next, the technical concept understood from the above embodiments and modifications will be described using the reference numerals, etc., from the embodiments and modifications. However, the reference numerals in the following description do not limit the components in the claims to the members, etc., specifically shown in the embodiments and modifications.

[0095] [1] A position detection device (stroke sensor 1) for detecting the position of a moving member (rack shaft 13) that moves back and forth in a predetermined direction of movement, comprising: an excitation coil (33) arranged along the moving member (13) and extending in the direction of movement; detection coils (31, 32) that output a voltage corresponding to the position of a detected part (21, 22) that moves together with the moving member (13) within a predetermined detection range in the direction of movement due to the magnetic field generated by the excitation coil (33); and a calculation unit (40) that calculates the position of the moving member (13) based on the output voltage of the detection coils (31, 32), wherein the detection coils (31, 32) consist of a pair of coil elements (311, 312, 32) whose output voltage changes according to the position of the moving member (13) A position detection device (1) having 1,322), wherein the phases of the output voltages of the pair of coil elements (311,312,321,322) are different from each other when the movable member (13) moves within the detection range, and at least one of the pair of coil elements (312,322) has a main coil section (313,323) that generates a voltage corresponding to the position of the detected part (21,22) by the magnetic field generated by the excitation coil (33) when the position of the detected part (21,22) is within the detection range, and a sub-coil section (314,324) that generates a voltage by the magnetic field generated by the excitation coil (33) when the position of the detected part (21,22) is outside the detection range.

[0096] [2] Each of the pair of coil elements (311, 312, 321, 322) is a combination of two sinusoidal conductor wires (301a, 302a, 303a, 304a, 301b, 302b, 303b, 304b) whose shape, when viewed from a direction perpendicular to the direction of movement, is symmetrical across symmetrical axes of symmetry (A1, A2) parallel to the direction of movement. The position detection device (1) described in [1] above, wherein, of the pair of coil elements (311, 312, 321, 322), the coil element (312, 322) that has a larger distance between the conductor wires (301a, 302a, 303a, 304a, 301b, 302b, 303b, 304b) at the end of the detection coil (31, 32) has the sub-coil portion (314, 324) at that end.

[0097] [3] The position detection device (1) described in [1] above, wherein the calculation unit (40) determines the position of the moving member (13) according to the result of division with the output voltage of at least one of the coil elements (312, 322) having the sub-coil section (314, 324) as the denominator.

[0098] [4] A position detection device (1) according to [1] above, having a plurality of detection coils (31, 32), wherein the plurality of detection coils (31, 32) are arranged perpendicular to the extending direction of the excitation coil (33), and the plurality of detected parts (21, 22) are arranged at different positions in the direction of movement corresponding to the plurality of detection coils (31, 32), and the detection range of each of the plurality of detection coils (31, 32) is offset in the direction of movement of the moving member (13).

[0099] [5] The position detection device (1) described in [4] above, wherein the calculation unit (40) performs a division for each of the plurality of detection coils (31, 32) with the output voltage of at least one of the coil elements (312, 322) having the sub-coil section (314, 324) as the denominator, and determines the position of the moving member (13) by the output voltage of the detection coil (31, 32) whose absolute value of the result of the division is larger.

[0100] [6] The position detection device (1) according to [4] above, wherein the excitation coil (33) and a plurality of the detection coils (31, 32) are formed on a single substrate (3, 3A), and the excitation coil (33) is formed on the substrate (3, 3A) so as to surround the plurality of detection coils (31, 32).

[0101] [7] A position detection device (1) according to any one of [1] to [6] above, having conductive members (target 2, first and second targets 2A, 2B) attached to the movable member, wherein the detected parts (21, 22) are formed on the conductive members (2, 2A, 2B).

[0102] Although embodiments and modifications of the present invention have been described above, the embodiments and modifications described above do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in each embodiment and modification are necessarily essential for solving the problem of the invention.

[0103] Furthermore, the present invention can be implemented with appropriate modifications without departing from its spirit. For example, in the above embodiment, the case in which the position of the rack shaft 13 is detected using the first and second detection coils 31 and 32 was described, but depending on the travel distance of the rack shaft 13 or the length of the substrate 3, it is also possible to detect the position of the rack shaft 13 using only the first detection coil 31, for example. Also, in the above embodiment, the case in which the moving member whose position is detected by the stroke sensor 1 is the rack shaft 13 of the steering device 10 was described, but the moving member to be detected is not limited to this, and may be a shaft for use in a vehicle or other vehicle. In addition, the shape of the moving member is not limited to an axial body, but can be various shapes such as a flat plate. [Explanation of symbols]

[0104] 1… Stroke sensor (position detection device) 2…Target (conductive component) 2A, 2B... First and second targets (conductive members) 13…Rack shaft (movable component) 21, 22... First and second detected parts 3,3A…board 31, 32… First and second detection coils 33…Excitation coil 301a, 302a, 303a, 304a... First curved section (conductor wire) 301b, 302b, 303b, 304b... Second curved section (conductor wire) 311,321…First and second sinusoidal coil elements 312,322…First and second cosine wave shaped coil elements 40...Arithmetic section

Claims

1. A position detection device for detecting the position of a moving member that moves back and forth in a predetermined direction, An excitation coil is arranged along the moving member, extending in the direction of movement, A detection coil that outputs a voltage corresponding to the position of the detected part moving together with the moving member within a predetermined detection range in the direction of movement, due to the magnetic field generated by the excitation coil, The system includes a calculation unit that calculates the position of the moving member based on the output voltage of the detection coil, 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 moves within the detection range. At least one of the pair of coil elements has a main coil section that generates a voltage corresponding to the position of the detected part by the magnetic field generated by the excitation coil when the position of the detected part is within the detection range, and a sub-coil section that generates a predetermined voltage by the magnetic field generated by the excitation coil when the position of the detected part is outside the detection range, wherein the voltage induced in the main coil section is approximately zero when the position of the detected part is outside the detection range, and no voltage is induced in the sub-coil section when the position of the detected part is within the detection range. Each of the pair of coil elements, excluding the sub-coil portion, has a shape formed by combining two sinusoidal conductor wires whose shape, when viewed from a direction perpendicular to the direction of movement, is symmetrical across a symmetry axis parallel to the direction of movement. Of the pair of coil elements, the coil element with a larger distance between the conductor wires at the end of the detection coil has the sub-coil portion at that end. Position detection device.

2. The calculation unit determines the position of the moving member according to the result of a division in which the output voltage of at least one of the coil elements having the sub-coil portion is used as the denominator. The position detection device according to claim 1.

3. Having a conductive member attached to the aforementioned movable member, The part to be detected is formed on the conductive member. The position detection device according to claim 1 or 2.

4. A position detection device for detecting the position of a moving member that moves forward and backward in a predetermined direction of movement, An excitation coil is arranged along the moving member, extending in the direction of movement, Multiple detection coils that output a voltage corresponding to the position of the detected part moving together with the moving member within a predetermined detection range in the direction of movement, due to the magnetic field generated by the excitation coil, The system includes a calculation unit that calculates the position of the moving member based on the output voltages of the plurality of detection coils, The plurality of detection coils are arranged in a direction perpendicular to the extending direction of the excitation coil, Multiple detected units are arranged at different positions in the direction of movement, corresponding to each of the multiple detection coils. The detection range of each of the plurality of detection coils is offset in the direction of movement of the moving member, Each of the plurality of detection coils has a pair of coil elements whose output voltage changes according to the position of the moving member, and when the moving member moves within the detection range of the detection coil, the phases of the output voltages of each of the pair of coil elements are different from each other. In each of the plurality of detection coils, at least one of the pair of coil elements has a main coil section that generates a voltage corresponding to the position of the detected part by the magnetic field generated by the excitation coil when the position of the detected part corresponding to the detection coil is within the detection range of the detection coil, and a sub-coil section that generates a predetermined voltage by the magnetic field generated by the excitation coil when the position of the detected part is outside the detection range of the detection coil, wherein the voltage induced in the main coil section is approximately zero when the position of the detected part is outside the detection range of the detection coil, and no voltage is induced in the sub-coil section when the position of the detected part is within the detection range of the detection coil. Position detection device.

5. The calculation unit performs a division for each of the plurality of detection coils with the output voltage of at least one of the coil elements having the sub-coil portion as the denominator, and determines the position of the moving member by the output voltage of the detection coil whose absolute value of the result of the division is larger. The position detection device according to claim 4.

6. The excitation coil and the plurality of detection coils are formed on a single substrate. The excitation coil is formed on the substrate so as to surround the plurality of detection coils. The position detection device according to claim 4.

7. Having a conductive member attached to the aforementioned movable member, Multiple detection portions are formed on the conductive member. A position detection device according to any one of claims 4 to 6.

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