Position detection device

Abstract

To provide a position detection device capable of detecting, with high accuracy, the position of a shaft that advances and retracts in the axial direction.SOLUTION: A position detection device 1 for detecting the position of a rack shaft 13 that advances and retracts in the axial direction within a predetermined movement range comprises: an excitation coil 4 that generates an AC magnetic field; a detector 2 that moves integrally with the rack shaft 13 and in which the magnetic flux of the AC magnetic field is linked; and a first detection coil 5 that has a detection section 51 that faces the detector 2 while the rack shaft 13 moves from an axial-direction one-side travel end to an axial-direction other-side travel end. An induced voltage induced in the detection section 51 by the magnetic flux of the AC magnetic field varies according to the position of the detector 2 relative to the detection section 51. The first detection coil 5 includes adjustment portions 52, 53 that suppress an influence of inclination of the rack shaft 13 relative to the detection section 51 on the induced voltage induced in the detection section 51.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a position detection device that detects the position of a shaft that moves back and forth in its axial direction within a predetermined movement range. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a position detecting device that detects the position of a shaft that moves back and forth in an axial direction has been used to detect the position of a rack shaft in a steering device of a vehicle, for example.

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

[0004] In the detection unit configured as described above, when the rack shaft moves axially due to rotation of the pinion gear shaft meshing with the rack shaft, changing the relative positions of the first to fourth magnetic resistance elements and the plurality of grooves, the balance of the electrical resistances of the first to fourth magnetic resistance elements changes, causing changes in the potentials of the first and second terminals. The calculation unit calculates the position of the rack shaft based on this change in potential. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2021 / 210125 Summary of the Invention [Problem to be solved by the invention]

[0006] In the detection unit described in Patent Document 1, if the rack shaft tilts in the vehicle width direction due to, for example, vibrations caused by the vehicle traveling, the distance between the first to fourth magnetic resistance elements and the rack shaft changes, causing an error in the detection position of the rack shaft.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a position detection device that can detect with high accuracy the position of a shaft that moves back and forth in its axial direction. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention provides a position detection device that detects the position of a metal shaft that moves back and forth in the axial direction within a predetermined range of movement, comprising: an excitation coil that generates an AC magnetic field; a detection body that moves integrally with the shaft and is interlinked with the magnetic flux of the AC magnetic field; and a detection coil having a detection part that faces the detection body as the shaft moves from one axial movement end to the other axial movement end, wherein an induced voltage induced in the detection part by the magnetic flux of the AC magnetic field changes depending on the position of the detection body relative to the detection part, and the detection coil has an adjustment part that suppresses the effect of the tilt of the shaft relative to the detection part on the induced voltage induced in the detection part. [Effects of the Invention]

[0009] According to the position detection device of the present invention, it is possible to detect with high precision the position of a shaft that moves back and forth in its axial direction. [Brief explanation of the drawings]

[0010] [Figure 1]1 is a schematic diagram of a vehicle equipped with a steer-by-wire steering device having a stroke sensor as a position detection device according to a first embodiment of the present invention. [Figure 2] 2 is a cross-sectional view of the rack shaft, the housing, the detection body, and the substrate taken along the line AA in FIG. 1. [Figure 3] FIG. 2 is a perspective view showing a rack shaft, a housing, a detection body, and a substrate. [Figure 4] 1(a) to 1(d) are explanatory diagrams showing the wiring patterns of the first wiring layer, the second wiring layer, the third wiring layer, and the fourth wiring layer of the substrate 3. FIG. [Figure 5] 1A is an explanatory diagram showing the wiring pattern of the first wiring layer and the wiring pattern of the third wiring layer superimposed on each other, and FIG. 1B is an explanatory diagram showing the wiring pattern of the second wiring layer and the wiring pattern of the fourth wiring layer superimposed on each other. [Figure 6] FIG. 2 is an explanatory diagram showing wiring patterns of a first wiring layer, a second wiring layer, a third wiring layer, and a fourth wiring layer superimposed on each other. [Figure 7] 10 is a graph showing an example of the relationship between the supply voltage supplied to the excitation coil from the power supply unit and the induced voltage induced in the first detection coil and the second detection coil 6. [Figure 8] 4 is an explanatory diagram schematically showing the relationship between the peak voltage, which is the peak value of the induced voltage induced in the first detection coil, and the position of the detection object. FIG. [Figure 9] 10 is an explanatory diagram schematically showing the relationship between the peak voltage, which is the peak value of the induced voltage induced in the second detection coil, and the position of the detection object. FIG. [Figure 10] 1A is an explanatory diagram showing a relationship between the inclination of the rack shaft with respect to the substrate and the effect of the inclination of the rack shaft on the magnetic flux density interlinked with the first detection coil, and FIG. 1B is an explanatory diagram showing a relationship between the inclination of the rack shaft with respect to the substrate and the effect of the inclination of the rack shaft on the magnetic flux density interlinked with the second detection coil. [Figure 11] 10 is a graph showing an increment in detection error of the position of the detection object due to tilting of the rack shaft with respect to the substrate when the first detection coil has and does not have an adjustment unit. [Figure 12] 10(a) to 10(d) are explanatory diagrams showing wiring patterns of first to fourth wiring layers of a substrate on which an adjustment section according to Modification 1 is formed. [Figure 13] 10 is an explanatory diagram showing the wiring patterns of the first to fourth wiring layers of a substrate on which an adjustment section according to Modification 1 is formed, superimposed one on the other; FIG. [Figure 14] 10(a) to 10(d) are explanatory diagrams showing wiring patterns of first to fourth wiring layers of a substrate on which an adjustment section according to Modification 2 is formed. [Figure 15] 10 is an explanatory diagram showing the wiring patterns of the first to fourth wiring layers of a substrate on which an adjustment section according to Modification 2 is formed, superimposed one on the other. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Embodiment Mode] FIG. 1 is a schematic diagram of a vehicle equipped with a steer-by-wire steering device 10 having a stroke sensor 1 as a position detection device according to a first embodiment of the present invention.

[0012] As shown in FIG. 1, the steering device 10 includes a stroke sensor 1, tie rods 12 connected to steered wheels 11 (left and right front wheels), a metal rack shaft 13 connected to the tie rods 12, a cylindrical housing 14 that accommodates the rack shaft 13, a worm reduction mechanism 15 having a pinion gear 151 meshed with rack teeth 131 of the rack shaft 13, an electric motor 16 that imparts axial moving force to the rack shaft 13 via the worm reduction mechanism 15, a steering wheel 17 that is 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] 1, the housing 14 is shown by an imaginary line. The rack shaft 13 is made of steel, such as carbon steel, and is supported by a pair of rack bushings 132 attached to both ends of the housing 14. The worm reduction mechanism 15 has a worm wheel 152 and a worm gear 153, and a pinion gear 151 is fixed to the worm wheel 152. The worm gear 153 is fixed to a motor shaft 161 of the electric motor 16.

[0014] The electric motor 16 generates torque by a motor current supplied from the steering control device 19, and rotates the worm wheel 152 and the pinion gear 151 via the worm gear 153. When the pinion gear 151 rotates, the rack shaft 13 moves back and forth in the axial direction within a predetermined movement range along the vehicle width direction, and the left and right steered wheels 11 are steered. The rack shaft 13 can move to the right and left in the vehicle width direction from a neutral position where the steering angle is zero. In FIG. 1, the range R1 within which the rack shaft 13 can move in the vehicle width direction is indicated by a double-headed arrow.

[0015] (Stroke sensor 1 configuration) The stroke sensor 1 includes a detection body 2 fixed to a rack shaft 13, a circuit board 3 arranged parallel to the rack shaft 13 and facing the detection body 2, a power supply unit 7, and a calculation unit 8. The circuit board 3, the power supply unit 7, and the calculation unit 8 are connected by a connector 91 and a cable 92 attached to the circuit board 3. The circuit board 3 is fixed inside a housing 14 parallel to the rack shaft 13. The stroke sensor 1 detects the position of the rack shaft 13 relative to the housing 14 from the position of the detection body 2, and outputs information about the detected position to a steering control device 19. 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 a steering angle sensor 18.

[0016] Fig. 2 is a cross-sectional view of the rack shaft 13, the housing 14, the detection body 2, and the substrate 3 taken along line AA in Fig. 1. Fig. 3 is a perspective view showing the rack shaft 13, the main body 141 of the housing 14, the detection body 2, and the substrate 3. In Fig. 3, the central axis C of the rack shaft 13 is indicated by a dashed dotted line. The rack shaft 13 moves along the central axis C due to a moving force applied by the electric motor 16.

[0017] The rack shaft 13 is a rod-like body with a circular cross section. The housing 14 has a metal main body 141 and a resin lid 142, and the lid 142 is fixed to the main body 141 by, for example, adhesive. The main body 141 has a U-shaped cross section in which an accommodation space 140 for accommodating the rack shaft 13 is formed, and the accommodation space 140 is open vertically upward. The diameter D of the rack shaft 13 is, for example, 25 mm.

[0018] A gap of, for example, 1 mm or more is formed between the outer peripheral surface 13a of the rack shaft 13 and the inner surface 140a of the storage space 140. The lid 142 is formed in a flat plate shape and covers the upper part of the storage space 140 in the vertical direction. The main body 141 is a non-magnetic material, for example, made of a die-cast aluminum alloy. The material of the lid 142 is not necessarily limited to resin, but it is desirable to use a non-magnetic and non-conductive material.

[0019] The detection body 2 is fixed to the rack shaft 13 so as to protrude from the outer peripheral surface 13a of the rack shaft 13 toward the substrate 3, and moves integrally with the rack shaft 13. The detection body 2 can be fixed to the rack shaft 13 by a fixing means such as adhesive or welding. The detection body 2 is made of a material having a higher magnetic permeability than the rack shaft 13, or a material having a higher electrical conductivity than the rack shaft 13. When using a material for the detection body 2 having a higher magnetic permeability than the rack shaft 13, it is desirable to use a magnetic material such as ferrite, which has high electrical resistance and is less likely to generate eddy currents. When using a material for the detection body 2 having a higher electrical conductivity than the rack shaft 13, the material can be, for example, a metal containing aluminum or copper as its main component.

[0020] In this embodiment, since the detection body 2 protrudes from the outer peripheral surface 13a of the rack shaft 13 toward the substrate 3, the actions and effects described below can be obtained even if a material having the same magnetic permeability as the rack shaft 13 or a material having the same electrical conductivity as the rack shaft 13 is used as the material for the detection body 2. However, in order to improve the position detection accuracy, it is desirable to use a high-permeability material having a higher magnetic permeability than the material of the rack shaft 13 or a high-electrical conductivity material having the same electrical conductivity as the material of the rack shaft 13 as the material for the detection body 2.

[0021] The opposing surface 2a of the detection element 2 facing the substrate 3 is formed in a flat shape and faces the front surface 3a of the substrate 3 in parallel with each other via an air gap G. The back surface 3b of the substrate 3 is fixed to the lid 142 with an adhesive 143. The opposing surface 2a of the detection element 2 as seen from the substrate 3 side is rectangular. The width W of the air gap G is, for example, 1 mm. The minimum thickness T of the detection element 2 in the direction perpendicular to the opposing surface 2a is, for example, 3 mm. Note that in this embodiment, the rack shaft 13 is formed to have a circular cross section, but the cross section of the rack shaft 13 is not limited to a circle and may be, for example, a D-shape with a portion formed linearly, or a polygonal shape.

[0022] The substrate 3 is a four-layer substrate having, in order from the surface 3a side, a first wiring layer 31, a second wiring layer 32, a third wiring layer 33, and a fourth wiring layer 34. The first wiring layer 31 and the fourth wiring layer 34 are outer layers of the substrate 3, and the second wiring layer 32 and the third wiring layer 33 are inner layers of the substrate 3. Base materials 30 made of a dielectric material such as FR4 (glass fiber impregnated with epoxy resin and subjected to a thermosetting process) are disposed between the first wiring layer 31 and the second wiring layer 32, between the second wiring layer 32 and the third wiring layer 33, and between the third wiring layer 33 and the fourth wiring layer 34. The first wiring layer 31 and the fourth wiring layer 34 are covered with an electrically insulating resist film 300. Wiring patterns are formed on the first wiring layer 31, the second wiring layer 32, the third wiring layer 33, and the fourth wiring layer 34, respectively, and the wiring patterns of these layers are connected at multiple locations on the substrate 3 by vias 35. The base plate 3 has a flat rectangular shape with the axial direction of the rack shaft 13 as the longitudinal direction.

[0023] (Configuration of board 3) Next, the wiring configuration of the substrate 3 will be described in detail with reference to FIGS. 4 to 6. FIGS. 4(a) to 4(d) are explanatory diagrams showing the wiring patterns of the first wiring layer 31, the second wiring layer 32, the third wiring layer 33, and the fourth wiring layer 34 as viewed from the front surface 3a side. FIG. 5(a) is an explanatory diagram showing the wiring pattern of the first wiring layer 31 shown in FIG. 4(a) superimposed on the wiring pattern of the third wiring layer 33 shown in FIG. 4(c). FIG. 5(b) is an explanatory diagram showing the wiring pattern of the second wiring layer 32 shown in FIG. 4(b) superimposed on the wiring pattern of the fourth wiring layer 34 shown in FIG. 4(d). FIG. 6 is an explanatory diagram showing the wiring patterns of the first wiring layer 31, the second wiring layer 32, the third wiring layer 33, and the fourth wiring layer 34 superimposed on each other as shown in FIGS. 4(a) to 4(d). In FIGS. 5(a), 5(b), and 6, the wiring pattern of the third wiring layer 33 and the wiring pattern of the fourth wiring layer 34 are shown in gray. The wiring patterns of each layer shown in Figures 4 to 6 are merely examples, and various types of wiring patterns can be adopted as long as the substrate 3 is formed so as to obtain the effects of the present invention.

[0024] On the substrate 3, an excitation coil 4 that generates an AC magnetic field, and a first detection coil 5 and a second detection coil 6 that are linked by the magnetic flux of the AC magnetic field generated by the excitation coil 4 are formed by a wiring pattern. The excitation coil 4 is formed across the first wiring layer 31 and the third wiring layer 33. The first detection coil 5 is formed across the first wiring layer 31 and the third wiring layer 33, and the second detection coil 6 is formed across the second wiring layer 32 and the fourth wiring layer 34. The first detection coil 5 corresponds to the "detection coil" of the present invention recited in the claims.

[0025] The excitation coil 4, the first detection coil 5, and the second detection coil 6 extend in the longitudinal direction of the substrate 3, which is along the axial direction of the rack shaft 13. An input / output unit 36 having first to sixth through-hole lands 361 to 366 for inserting a plurality of connector pins of the connector 91 shown in Fig. 1 is formed at one longitudinal end of the substrate 3. Hereinafter, of both longitudinal sides of the substrate 3, the side on which the input / output unit 36 is formed will be referred to as one longitudinal side, and the opposite side will be referred to as the other longitudinal side.

[0026] (Configuration of excitation coil 4) The excitation coil 4 has a pair of long sides 41, 42 extending in the longitudinal direction of the substrate 3, a pair of short sides 43, 44 between the pair of long sides 41, 42, and a connection line portion 45 between the input / output unit 36 and the short side 43 of the pair of short sides 43, 44 on one side in the longitudinal direction. The long sides 41, 42 of the excitation coil 4 are formed by conductor lines 411, 421 formed on the first wiring layer 31 and conductor lines 412, 422 formed on the third wiring layer 33. The short sides 43, 44 of the excitation coil 4 are formed by conductor lines 431, 441 formed on the first wiring layer 31 and conductor lines 432, 442 formed on the third wiring layer 33. The connection line portion 45 is formed by a conductor line 451 formed on the first wiring layer 31 and a conductor line 452 formed on the third wiring layer 33. The conductor line 451 of the connection line portion 45 is connected to the first through-hole land 361 of the input / output portion 36 , and the conductor line 452 is connected to the sixth through-hole land 366 .

[0027] The first detection coil 5 and the second detection coil 6 are formed inside a pair of long sides 41, 42 and a pair of short sides 43, 44 of the rectangular excitation coil 4. An AC current is supplied to the excitation coil 4 from a power supply unit 7 via a connector 91 and a cable 92. The excitation coil 4 generates an AC magnetic field with a frequency corresponding to the frequency of the AC current. The magnetic flux of the AC magnetic field generated by the excitation coil 4 interlinks with the first detection coil 5 and the second detection coil 6, generating an induced voltage corresponding to the frequency of the AC magnetic field.

[0028] The magnetic flux of the AC magnetic field generated by the excitation coil 4 also links with the detection body 2. The magnetic flux linking with the detection body 2 affects the intensity distribution of the magnetic flux linking with the first detection coil 5 and the second detection coil 6, and the magnitude of the induced voltage generated in the first detection coil 5 and the second detection coil 6 by the AC magnetic field generated by the excitation coil 4 changes depending on the position of the detection body 2. In Figure 6, the position of the detection body 2 when the rack shaft 13 is at one end of movement in the axial direction is shown by a dashed line, and the position of the detection body 2 when the rack shaft 13 is at the other end of movement in the axial direction is shown by a two-dot chain line.

[0029] While the rack shaft 13 moves from one axial movement end to the other axial movement end, the magnitudes of the induced voltages induced in the first detection coil 5 and the second detection coil 6 change depending on the position of the detection body 2, and the phases of the magnitudes of the induced voltages induced in the first detection coil 5 and the second detection coil 6 differ from each other by 90°. In this embodiment, while the rack shaft 13 moves from one axial movement end to the other axial movement end, the phases of the changes in the magnitudes of the induced voltages induced in the first detection coil 5 and the second detection coil 6 differ from each other by 90°.

[0030] (Configuration of first detection coil 5) The first detection coil 5 has a detection unit 51 that faces the detection body 2 while the rack shaft 13 moves from one axial movement end to the other axial movement end, two adjustment units 52 and 53 provided on both sides of the detection unit 51 in the longitudinal direction of the substrate 3, and a connection line unit 54 for connection to the input / output unit 36. The adjustment units 52 and 53 suppress the effect of the inclination of the rack shaft 13 relative to the substrate 3 and the detection unit 51 on the induced voltage induced in the detection unit 51. The action and effect of the adjustment units 52 and 53 will be described later.

[0031] The detection unit 51 has a shape made up of a pair of curved portions 511 and 512. In the example shown in FIGS. 4 to 6, the curved portion 511 is formed in the first wiring layer 31, and the curved portion 512 is formed in the third wiring layer 33. The curved portions 511 and 512 are sinusoidal conductor lines that are symmetric in the width direction of the substrate 3 with respect to a symmetry axis 510 that extends in the longitudinal direction of the substrate 3 and the detection unit 51. More specifically, the shape of the curved portion 511 in the first wiring layer 31 when viewed from the normal direction of the substrate 3 is a sinusoidal wave shape ranging from −180° to 180° when the symmetry axis 510 is regarded as the phase axis as shown in FIG. 4(a), and the shape of the curved portion 512 in the third wiring layer 33 when viewed from the normal direction of the substrate 3 is a sinusoidal wave shape ranging from 0° to 360° when the symmetry axis 510 is regarded as the phase axis as shown in FIG. 4(c).

[0032] 5(a), one curved portion 511 and the other curved portion 512 constituting the detection unit 51 cross each other without contacting (short-circuiting) each other at a central portion 51C in the longitudinal direction of the detection unit 51. The curved portions 511 and 512 are close to each other toward the axis of symmetry 510 at both ends in the longitudinal direction of the detection unit 51, and there is a wide gap between these ends and the central portion 51C.

[0033] The shape of each of the adjustment units 52 and 53 is rectangular when viewed from the normal direction of the substrate 3. The adjustment unit 52 provided on one longitudinal side of the detection unit 51 is composed of a conductor line 521 formed on the first wiring layer 31 and continuing from one longitudinal end of the curved portion 511 that constitutes the detection unit 51, and a conductor line 522 formed on the third wiring layer 33 and continuing from one longitudinal end of the curved portion 512 that constitutes the detection unit 51. The adjustment unit 53 provided on the other longitudinal side of the detection unit 51 is composed of a conductor line 531 formed on the first wiring layer 31 and continuing from the other longitudinal end of the curved portion 511 that constitutes the detection unit 51, and a conductor line 532 formed on the third wiring layer 33 and continuing from the other longitudinal end of the curved portion 512 that constitutes the detection unit 51. The conductor line 531 and the conductor line 532 are connected by a via 35 at the other longitudinal end of the adjustment unit 53.

[0034] The connection line portion 54 connects the adjustment portion 52 on one longitudinal side to the input / output portion 36. In the present embodiment, the connection line portion 54 is configured by a conductor line 541 that connects one longitudinal end of the conductor line 521 of the adjustment portion 52 to the fifth through-hole land 365, and a conductor line 542 that connects one longitudinal end of the conductor line 522 of the adjustment portion 52 to the fourth through-hole land 364. The conductor line 541 is formed in the first wiring layer 31 along the symmetry axis 510. The conductor line 542 is formed in the third wiring layer 33 along the symmetry axis 510.

[0035] When the short direction perpendicular to the longitudinal direction of substrate 3 is defined as the width direction, curved portion 511 constituting detection unit 51 has a portion on one longitudinal side of central portion 51C that is provided on one width side of symmetry axis 510 (lower side in the drawing), and a portion on the other longitudinal side of central portion 51C that is provided on the other width side of symmetry axis 510 (upper side in the drawing). Conductor wire 521 of adjustment unit 52, which is formed continuously with the end portion on one longitudinal side of curved portion 511, is provided on the other width side of symmetry axis 510 (upper side in the drawing), and conductor wire 531 of adjustment unit 53, which is formed continuously with the end portion on the other longitudinal side of curved portion 511, is provided on one width side of symmetry axis 510 (lower side in the drawing).

[0036] Furthermore, curved portion 512, which constitutes detection unit 51 together with curved portion 511, has a portion on one longitudinal side of central portion 51C provided on the other widthwise side of symmetry axis 510 (upper side in the drawing), and a portion on the other longitudinal side of central portion 51C provided on one widthwise side of symmetry axis 510 (lower side in the drawing). Conductor wire 522 of adjustment portion 52, which is formed continuously with the end portion on one longitudinal side of curved portion 512, is provided on one widthwise side of symmetry axis 510 (lower side in the drawing), and conductor wire 532 of adjustment portion 53, which is formed continuously with the end portion on the other longitudinal side of curved portion 512, is provided on the other widthwise side of symmetry axis 510 (upper side in the drawing).

[0037] Due to the configuration of the first detection coil 5, the direction of the induced voltage generated in one side portion 51A, which is a portion on one side of the central portion 51C in the detection unit 51 in the longitudinal direction, is opposite to the direction of the induced voltage generated in the adjustment unit 52 provided on one side of the detection unit 51 in the longitudinal direction. Also, the direction of the induced voltage generated in the other side portion 51B, which is a portion on the other side of the central portion 51C in the detection unit 51 in the longitudinal direction, is opposite to the direction of the induced voltage generated in the adjustment unit 53 provided on the other side of the detection unit 51 in the longitudinal direction.

[0038] In FIG. 5(a), when the strength of the magnetic field gradually increases from the front side of the drawing to the back side of the drawing, the direction of the current that may be generated in the curved portions 511 and 512 of the detection unit 51, the conductor wires 521 and 522 of the adjustment unit 52, and the conductor wires 531 and 532 of the adjustment unit 53 due to this change in the strength of the magnetic field is indicated by arrow A. 51 , Arrow A 52 , Arrow A 53 If the detection body 2 is not attached to the rack shaft 13 and the symmetry axis 510 and the central axis C of the rack shaft 13 are parallel, the induced voltage generated in the one-side portion 51A and the induced voltage generated in the other-side portion 51B are balanced and canceled out, and the induced voltage generated in the adjustment portion 52 on one longitudinal side and the induced voltage generated in the adjustment portion 53 on the other longitudinal side are balanced and canceled out, so that no current flows through the first detection coil 5.

[0039] In this embodiment, the maximum width W of the detection unit 51 in the width direction of the substrate 3 is 51 and the maximum width W of the adjustment parts 52 and 53 52 ,W 53 More specifically, the maximum width W of the adjustment portions 52 and 53 is equal to 52 ,W 53 is the maximum width W of the detection section 51 51 The ratio is 95% to 105% of the total length of the detecting unit 51. This configuration effectively utilizes the space of the substrate 3 on one longitudinal side and the other longitudinal side of the detecting unit 51 as space for the adjusting units 52 and 53, contributing to the miniaturization of the substrate 3. Between the pair of short side portions 43 and 44 of the exciting coil 4 and the adjusting units 52 and 53, there is provided an empty space to prevent the magnetic field generated by the current flowing through the short side portions 43 and 44 from affecting the induced voltage generated in the adjusting units 52 and 53.

[0040] (Configuration of second detection coil 6) The second detection coil 6 has a detection portion 61 that faces the detection body 2 while the rack shaft 13 moves from one axial movement end to the other axial movement end, and a connection line portion 62 for connection to the input / output portion 36. The position and length of the detection portion 61 in the longitudinal direction of the substrate 3 are the same as the position and length of the detection portion 51 of the first detection coil 5, and the detection portion 61 of the second detection coil 6 and the detection portion 51 of the first detection coil 5 overlap in the thickness direction of the substrate 3.

[0041] The detection unit 61 is composed of a pair of curved portions 611, 612 that are symmetrical in the width direction of the substrate 3 across a symmetry axis 610 that extends in the longitudinal direction of the substrate 3, linear portions 613, 614 that extend from one axial end of each of the curved portions 611, 612 toward the symmetry axis 610 along the width direction of the substrate 3, and linear portions 615, 616 that extend from the other axial end of each of the curved portions 611, 612 toward the symmetry axis 610 along the width direction of the substrate 3. The curved portion 611 and the linear portions 613, 615 are formed in the second wiring layer 32. The curved portion 612 and the linear portions 614, 616 are formed in the fourth wiring layer 34.

[0042] The pair of curved portions 611, 612 are sinusoidal conductor lines that are symmetrical in the width direction of the substrate 3 with respect to a symmetry axis 610 extending in the longitudinal direction of the substrate 3 and the detection unit 61. More specifically, the shape of the curved portion 611 in the second wiring layer 32 viewed from the normal direction of the substrate 3 is a cosine wave shape ranging from 0° to 360° when the symmetry axis 610 is regarded as the phase axis as shown in FIG. 4(b), and the shape of the curved portion 612 in the fourth wiring layer 34 viewed from the normal direction of the substrate 3 is a cosine wave shape ranging from -180° to 180° when the symmetry axis 610 is regarded as the phase axis as shown in FIG. 4(d). The pair of curved portions 611, 612 cross at two intersections 601, 602 in the longitudinal direction of the detection unit 61. A straight line portion 615 of the second wiring layer 32 and a straight line portion 616 of the fourth wiring layer 34 extending from the other axial end of the pair of curved lines 611 and 612 are connected by a via 35 .

[0043] The connection line portion 62 connects one axial end of the pair of curved portions 611, 612 to the input / output portion 36. In this embodiment, the connection line portion 62 is configured by a conductor line 621 that connects one longitudinal end of the curved portion 611 to the second through-hole land 362, and a conductor line 622 that connects one longitudinal end of the curved portion 612 to the third through-hole land 363. The conductor line 621 is formed in the second wiring layer 32 along the axis of symmetry 610. The conductor line 622 is mainly formed in the fourth wiring layer 34 along the axis of symmetry 610, but the portion that intersects with the short side portion 43 of the excitation coil 4 is formed in the third wiring layer 33 through a plurality of vias 35.

[0044] The first and second detection coils 5 and 6 output output signals, which are voltages induced by the AC magnetic field generated by the excitation coil 4, to the calculation unit 8 via a connector 91 and a cable 92. The calculation unit 8 calculates the position of the detection object 2 based on these output signals and transmits the calculation result to the steering control device 19. The peak values of the voltages induced in the first and second detection coils 5 and 6 change within a range of one cycle or less while the rack shaft 13 moves from one axial movement end to the other axial movement end. This allows the stroke sensor 1 to detect the absolute position of the rack shaft 13 throughout the entire range R1 over which the rack shaft 13 can move in the axial direction.

[0045] (Stroke sensor 1 operation) Next, the operation of the stroke sensor 1 for detecting the position of the detection body 2 relative to the substrate 3 will be described with reference to Figures 7 to 9. In the following description, the position of the detection body 2 refers to the position of the center point 20 (see Figure 3) of the opposing surface 2a in the axial direction. Furthermore, the overlapping of the first detection coil 5 and the second detection coil 6 with the detection body 2 means that the first detection coil 5, the second detection coil 6 and the detection body 2 are aligned along the normal direction of the substrate 3.

[0046] 7 is a graph showing an example of the relationship between the supply voltage V0 supplied to the excitation coil 4 from the power supply unit 7 and the induced voltage V1 induced in the first detection coil 5 and the induced voltage V2 induced in the second detection coil 6 when the detection object 2 overlaps with the detection units 51 and 61 of the first detection coil 5 and the second detection coil 6. The horizontal axis of the graph in FIG. 7 is the time axis, and the left and right vertical axes represent the supply voltage V0 and the induced voltages V1 and V2.

[0047] 7, the supply voltage V0 and the induced voltages V1 and V2 are in phase, but the induced voltage V1 induced in the first detection coil 5 switches between in-phase and out-of-phase every time the detection object 2 passes the center portion 51C of the detection section 51 of the first detection coil 5. Similarly, the induced voltage V2 induced in the second detection coil 6 switches between in-phase and out-of-phase every time the detection object 2 passes through the intersections 601 and 602 where a pair of curved portions 611 and 612 cross. A high-frequency AC voltage of, for example, about 1 MHz to 1 GHz is supplied to the excitation coil 4 as the supply voltage V0.

[0048] Fig. 8 is an explanatory diagram that schematically shows the relationship between the peak voltage Vs, which is the peak value of the induced voltage V1 induced in the first detection coil 5, and the position of the detection object 2. Fig. 9 is an explanatory diagram that schematically shows the relationship between the peak voltage Vc, which is the peak value of the induced voltage V2 induced in the second detection coil 6, and the position of the detection object 2. In the graphs of peak voltages Vs and Vc shown in Figs. 8 and 9, the horizontal axis represents the position of the detection object 2.

[0049] The stroke sensor 1 can detect the absolute position of the detection body 2 in the range where the entire axial length of the detection body 2 in the axial direction of the rack shaft 13 overlaps with the detection sections 51, 61 of the first detection coil 5 and the second detection coil 6. In the graphs shown in Figures 8 and 9, the horizontal axis coordinate of the detection body 2 when the rack shaft 13 is at one end of movement in the axial direction is set to P1, and the horizontal axis coordinate of the detection body 2 when the rack shaft 13 is at the other end of movement in the axial direction is set to P2, and the peak voltages Vs, Vc at each position are shown.

[0050] 8 and 9, the peak voltage Vs of the first detector coil 5 is positive when the induced voltage V1 induced in the first detector coil 5 is in phase with the supply voltage V0 supplied to the excitation coil 4, and is negative when it is out of phase with it. Similarly, the peak voltage Vc of the second detector coil 6 is positive when the induced voltage V2 induced in the second detector coil 6 is in phase with the supply voltage V0 supplied to the excitation coil 4, and is negative when it is out of phase with it.

[0051] Here, if ωx is defined as in equation [1], the peak voltages Vs and Vc can be calculated by equations [2] and [3], respectively, where Xp is the horizontal coordinate value of the detection object 2 in the graphs shown in Figures 8 and 9. In equation [1], L1 is the longitudinal length of the detection sections 51 and 61 of the first detection coil 5 and the second detection coil 6. In equations [2] and [3], A is a predetermined constant, and L2 is the axial length of the detection object 2.

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[0052] (Actions and Effects of Adjustment Units 52, 53 of First Detection Coil 5) For example, if the rack shaft 13 tilts relative to the substrate 3 due to vibrations while the vehicle is running, and the distance between each part of the substrate 3 and the rack shaft 13 changes, the degree to which the rack shaft 13 affects the magnetic flux intensity distribution inside the excitation coil 4 will change depending on the longitudinal position of the substrate 3. In this embodiment, the influence of the tilt of the rack shaft 13 on the detection accuracy of the position of the detection object 2 is suppressed by the adjustment units 52 and 53 of the first detection coil 5. Next, the action and effect of the adjustment units 52 and 53 will be described by comparison with a comparative example.

[0053] FIG. 10(a) is an explanatory diagram schematically illustrating the relationship between the inclination of the rack shaft 13 with respect to the substrate 3 and the effect of the inclination of the rack shaft 13 on the magnetic flux density interlinked with the first detection coil 5. FIG. 10(b) is an explanatory diagram schematically illustrating the relationship between the inclination of the rack shaft 13 with respect to the substrate 3 and the effect of the inclination of the rack shaft 13 on the magnetic flux density interlinked with the second detection coil 6. In FIGS. 10(a) and 10(b), the bisector BL of the detection sections 51, 61 of the first detection coil 5 and the second detection coil 6 is indicated by a two-dot chain line, and the rack shaft 13 is shown tilted in the vertical direction of the drawing around a point indicated by a target mark TM on this bisector BL. The rack shaft 13 is tilted so that the portion to the left of the target mark TM in the drawing is close to the substrate 3 and the portion to the right of the target mark TM in the drawing is farther away from the substrate 3. Note that in FIGS. 10(a) and 10(b), the inclination of the rack shaft 13 is exaggerated.

[0054] Eddy currents flow in the rack shaft 13 due to the magnetic flux of the AC magnetic field generated by the excitation coil 4 linking with it. These eddy currents act to weaken the magnetic flux linking with the first detection coil 5 and the second detection coil 6. The effect of this effect becomes greater as the distance between the rack shaft 13 and the substrate 3 becomes shorter. In FIGS. 10(a) and 10(b), the regions inside the first detection coil 5 and the second detection coil 6 where this effect becomes greater when the rack shaft 13 tilts are shown in dark gray, and the regions inside the first detection coil 5 and the second detection coil 6 where this effect becomes smaller when the rack shaft 13 tilts are shown in light gray.

[0055] 10(a), in one side portion 51A of the detection unit 51 of the first detection coil 5 and the adjustment unit 52, the rack shaft 13 is tilted as shown, which increases the influence of eddy currents generated in the rack shaft 13, resulting in a lower magnetic flux density. This influence is greater in the adjustment unit 52, which is located farther from the bisector BL, than in the one side portion 51A of the detection unit 51. Furthermore, in the other side portion 51B of the detection unit 51 of the first detection coil 5 and the adjustment unit 53, the rack shaft 13 is tilted as shown, which decreases the influence of eddy currents generated in the rack shaft 13, resulting in a higher magnetic flux density. This influence is greater in the adjustment unit 53, which is located farther from the bisector BL, than in the other side portion 51B of the detection unit 51.

[0056] However, the sum of the amount of change in the induced voltage V1 of the first detection coil 5 caused by the decrease in the magnetic flux density in the one side portion 51A of the detection unit 51 and the amount of change in the induced voltage V1 of the first detection coil 5 caused by the increase in the magnetic flux density in the other side portion 51B of the detection unit 51, and the sum of the amount of change in the induced voltage V1 of the first detection coil 5 caused by the decrease in the magnetic flux density in the adjustment unit 52 and the amount of change in the induced voltage V1 of the first detection coil 5 caused by the increase in the magnetic flux density in the adjustment unit 53 cancel each other out. This makes it possible to improve the accuracy of detecting the position of the detection object 2, i.e., the position of the rack shaft 13.

[0057] In addition, the influence of the change in magnetic flux density caused by the inclination of the rack shaft 13 with respect to the substrate 3 is greater in the adjustment portions 52 and 53 than in the one side portion 51A and the other side portion 51B of the detection portion 51. Therefore, the maximum width W of the detection portion 51 in the width direction of the substrate 3 is 51 and the maximum width W of the adjustment parts 52 and 53 52 ,W 53 When the length L of the adjustment portion 52 in the longitudinal direction of the substrate 3 is equal to the length L of the adjustment portion 52 in the longitudinal direction of the substrate 3, 52 is the length L of the one side portion 51A of the first detection coil 5. 51A The length L of the adjustment portion 53 in the longitudinal direction of the substrate 3 is shorter than 53 is the length L of the other side portion 51B of the first detection coil 5. 51BEven if it is shorter, the change in induced voltage V1 of the first detection coil 5 due to the change in magnetic flux density in one side portion 51A and the other side portion 51B of the detection unit 51 caused by the tilting of the rack shaft 13 and the change in induced voltage V1 of the first detection coil 5 due to the change in magnetic flux density in the adjustment units 52 and 53 can be offset.

[0058] By a geometric analysis taking into consideration the change in magnetic flux density due to the inclination of the rack shaft 13 relative to the substrate 3, the maximum width W of the detection unit 51 in the width direction of the substrate 3 was determined. 51 and the maximum width W of the adjustment parts 52 and 53 52 ,W 53 When the lengths L of the adjustment parts 52 and 53 in the longitudinal direction of the substrate 3 are the same, 52 ,L 53 is the longitudinal length L1 (L1=L 51A +L 51B ), it has been found that when the magnetic flux density at one side portion 51A and the other side portion 51B of the detection unit 51 is increased or decreased, the amount of change in the induced voltage V1 of the first detection coil 5 due to the increase or decrease in the magnetic flux density at the adjustment units 52 and 53 is equal to the amount of change in the induced voltage V1 of the first detection coil 5 due to the increase or decrease in the magnetic flux density at the adjustment units 52 and 53, and that even if the rack shaft 13 is tilted with respect to the substrate 3, the induced voltage V1 does not fluctuate.

[0059] Note that, due to the configuration of the second detection coil 6, even if the rack shaft 13 is tilted with respect to the substrate 3, the change in the induced voltage V2 is suppressed. As shown in FIG. 10(b), when the inner region of the detection unit 61 of the second detection coil 6 is divided into a first section 61A, a second section 61B, a third section 61C, and a fourth section 61D in the longitudinal direction, the influence of the change in magnetic flux density caused by the tilt of the rack shaft 13 on the induced voltage V2 is canceled out in the second section 61B and the third section 61C, and also in the first section 61A and the fourth section 61D. Here, the first section 61A is a region on one side of the intersection 601 in the longitudinal direction. The second section 61B is a region between the center section 600 and the intersection 601 in the longitudinal direction of the detection unit 61. The third section 61C is a region between the center section 600 and the intersection 602. The fourth section 61D is an area on the other side of the intersection 602 in the longitudinal direction.

[0060] FIG. 11 is a graph showing the increase in the detection error of the position of the detection object 2 caused by the rack shaft 13 tilting relative to the substrate 3 when the first detection coil 5 has and does not have the adjustment units 52, 53. The horizontal axis of this graph shows the position of the detection object 2 on the - side (one axial side) and + side (the other axial side), with the position of the detection object 2 when the rack shaft 13 is in the neutral position being 0 mm. The vertical axis shows the increase in the detection error of the position of the detection object 2 caused by the rack shaft 13 tilting 0.5° in %FS (FS means full scale). The black circles (●) in the graph represent the evaluation results when the first detection coil 5 does not have the adjustment units 52, 53. The white circles (◯) in the graph represent the evaluation results when the first detection coil 5 has the adjustment units 52, 53. The adjustment units 52, 52 to be evaluated have a maximum width W 52 ,W 53 is the maximum width W of the detection part 51 51 The same as the longitudinal length L 52 ,L 53 is 14% of the length L1 of the detection portions 51 and 61 of the first detection coil 5 in the longitudinal direction.

[0061] As shown in FIG. 11, the first detection coil 5 has the adjustment units 52 and 53, so that the error in the position of the detected object 2 is significantly reduced.

[0062] [Modification 1 of Adjustment Units 52 and 53] Next, Modification 1 of the adjustment units 52 and 53 will be described with reference to Fig. 12 and Fig. 13. Fig. 12(a) to (d) are explanatory diagrams showing the wiring patterns of the first wiring layer 31, the second wiring layer 32, the third wiring layer 33, and the fourth wiring layer 34 of the substrate 3 on which the adjustment units 52 and 53 according to Modification 1 are formed. Fig. 13 is an explanatory diagram showing the wiring patterns of the first wiring layer 31, the second wiring layer 32, the third wiring layer 33, and the fourth wiring layer 34 shown in Fig. 12(a) to (d) superimposed on each other.

[0063] In the above embodiment, the case where adjustment units 52 and 53 each have one turn has been described, but in Modification 1, adjustment units 52 and 53 each have three turns. More specifically, conductor wires 521 and 522 constituting adjustment unit 52 and conductor wires 531 and 532 constituting adjustment unit 53 each make 1.5 turns, thereby constituting adjustment units 52 and 53 each having three turns.

[0064] According to this modification 1, in addition to the effects of the above embodiment, the length of the adjustment parts 52 and 53 in the longitudinal direction of the substrate 3 can be made shorter than in the above embodiment, and the substrate 3 can be made smaller.

[0065] [Modification 2 of Adjustment Units 52 and 53] Next, a second modification of the adjustment units 52 and 53 will be described with reference to Fig. 14 and Fig. 15. Fig. 14(a) to (d) are explanatory diagrams showing the wiring patterns of the first wiring layer 31, the second wiring layer 32, the third wiring layer 33, and the fourth wiring layer 34 of the substrate 3 on which the adjustment units 52 and 53 according to the second modification are formed. Fig. 15 is an explanatory diagram showing the wiring patterns of the first wiring layer 31, the second wiring layer 32, the third wiring layer 33, and the fourth wiring layer 34 shown in Fig. 14(a) to (d) superimposed on each other.

[0066] In the configuration example of the adjustment units 52, 53 described with reference to Figures 4 and 5 in the above embodiment, the conductor wire 521 of the adjustment unit 52, which is formed continuously with the end on one longitudinal side of the curved portion 511 that constitutes the detection unit 51, and the conductor wire 532 of the adjustment unit 53, which is formed continuously with the end on the other longitudinal side of the curved portion 512 that constitutes the detection unit 51, are formed on the other widthwise side of the axis of symmetry 510 (upper side of the drawing), and the conductor wire 531 of the adjustment unit 53, which is formed continuously with the end on the other longitudinal side of the curved portion 511 that constitutes the detection unit 51, and the conductor wire 522 of the adjustment unit 52, which is formed continuously with the end on one longitudinal side of the curved portion 512 that constitutes the detection unit 51, are formed on one widthwise side of the axis of symmetry 510 (lower side of the drawing).However, in variant example 2, the arrangement of the conductor wires 521, 522, 531, 532 of the adjustment units 52, 53 in the widthwise direction of the substrate 3 is reversed from that described above. Furthermore, the way in which the conductor wires 521, 522, 531, and 532 run when traced from the curved portions 511 and 512 is opposite to that in the above embodiment.

[0067] This second modification also provides the same effects as those of the above embodiment due to the same actions.

[0068] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiments will be described by using the reference numerals and the like in the embodiments. However, the reference numerals in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiments.

[0069] [1] A position detection device (1) for detecting the position of a metal shaft (rack shaft 13) that moves back and forth in the axial direction within a predetermined range of movement, the position detection device (1) comprising: an excitation coil (4) that generates an AC magnetic field; a detection body (2) that moves integrally with the shaft (13) and is interlinked with the magnetic flux of the AC magnetic field; and a detection coil (5) having a detection portion (51) that faces the detection body (2) while the shaft (13) moves from one axial end to the other axial end, wherein an induced voltage induced in the detection portion (51) by the magnetic flux of the AC magnetic field varies depending on the position of the detection body (2) relative to the detection portion (51), and the detection coil (5) has adjustment portions (52, 53) that suppress the effect of the inclination of the shaft (13) relative to the detection portion (51) on the induced voltage induced in the detection portion (51).

[0070] [2] The position detection device (1) described in [1] above, wherein the detection unit (51) extends in a longitudinal direction along the axial direction of the shaft (13), and the adjustment units (52, 53) are provided on both sides of the detection unit (51) in the longitudinal direction.

[0071] [3] The detecting section (51) has a shape in which a pair of curved sections (511, 512) are combined to be symmetrical with respect to a symmetrical axis extending in the longitudinal direction, and the pair of curved sections (511, 512) intersect at a central section (51C) in the longitudinal direction of the detecting section (51). The direction of an induced voltage generated in a section (51A) on one side of the central section (51C) in the longitudinal direction of the detecting section (51) and the direction of an induced voltage generated in the detecting section (51) on the other side of the central section (51C) in the longitudinal direction are determined by the direction of the induced voltage. The position detection device (1) according to the above [2], wherein the direction of the induced voltage generated in the adjustment unit (52, 53) provided on one side of the central portion (51C) in the detection unit (51) in the longitudinal direction is opposite to the direction of the induced voltage generated in the portion (51B) on the other side of the central portion (51C) in the longitudinal direction, and the direction of the induced voltage generated in the adjustment unit (52, 53) provided on the other side of the detection unit (51) in the longitudinal direction is opposite to the direction of the induced voltage generated in the adjustment unit (52, 53) provided on the other side of the detection unit (51).

[0072] [4] The maximum width (W) of the detection unit (51) in the width direction perpendicular to the longitudinal direction51 ) and the maximum width (W 52 ,W 53 ) is equivalent to the position detection device (1) described in [3] above.

[0073] [5] The position detection device (1) according to any one of [1] to [4] above, wherein the excitation coil (4) and the detection coil (5) are formed on a single substrate (3).

[0074] [6] The position detection device (1) described in [5] above, wherein a second detection coil (6) having a shape formed by combining a pair of curved portions (611, 612) is formed on the substrate (3), and the phase of the change in magnitude of the induced voltage induced in the second detection coil (6) while the shaft (13) moves from the moving end on one side of the axial direction to the moving end on the other side of the axial direction is different by 90° from the phase of the change in magnitude of the induced voltage induced in the detection coil (5).

[0075] [7] The position detection device (1) according to the above [1], wherein the shaft (13) is a rack shaft (13) of a steering device (10) of a vehicle.

[0076] Although the embodiments of the present invention have been described above, the invention according to the claims is not limited to the above embodiments. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention. Furthermore, the present invention can be appropriately modified and implemented without departing from the spirit of the invention, and can be modified as follows, for example.

[0077] In the above embodiment, the first and second detection coils 5, 6 are described as having a sinusoidal shape, but the present invention is not limited to this and may have a triangular wave shape, for example. The excitation coil 4 and the first and second detection coils 5, 6 do not necessarily have to be formed on a single substrate. Furthermore, in the above embodiment, the object to be detected by the stroke sensor 1 is a rack shaft of a steering device, but the object to be detected according to the present invention is not limited to a rack shaft and may be applied to detecting the position of any metal shaft that moves back and forth in the axial direction. [Explanation of symbols]

[0078] 1... Stroke sensor 2... Detection object 3... Substrate 4... Excitation coil 5...First detection coil (detection coil) 51...Detection unit 510...Axis of symmetry 511, 512...Curved section 51A...One side part 51B...Other side part 51C...Central part 52,53...Adjustment part 6...Second detection coil

Claims

1. A position detection device that detects the position of a metal shaft that moves back and forth in an axial direction within a predetermined movement range, an excitation coil that generates an AC magnetic field; a detection body that moves integrally with the shaft and is interlinked with the magnetic flux of the AC magnetic field; a detection coil having a detection portion that faces the detection body while the shaft moves from one axial movement end to the other axial movement end, an induced voltage induced in the detection unit by the magnetic flux of the AC magnetic field varies depending on the position of the detection object relative to the detection unit; The detection coil has an adjustment unit that suppresses the influence of the tilt of the shaft with respect to the detection unit on the induced voltage induced in the detection unit. Position detection device.

2. the detection portion extends in a longitudinal direction along the axial direction of the shaft, The adjustment unit is provided on both sides of the detection unit in the longitudinal direction. The position detection device according to claim 1 .

3. the detection portion has a shape formed by combining a pair of curved portions that are symmetrical with respect to a symmetry axis extending in the longitudinal direction, the pair of curved portions cross at a center portion of the detection portion in the longitudinal direction, a direction of an induced voltage generated in a portion of the detection unit on one side of the central portion in the longitudinal direction is opposite to a direction of an induced voltage generated in the adjustment unit provided on one side of the detection unit in the longitudinal direction, a direction of an induced voltage generated in a portion of the detection unit on the other side of the central portion in the longitudinal direction is opposite to a direction of an induced voltage generated in the adjustment unit provided on the other side of the detection unit in the longitudinal direction. The position detection device according to claim 2 .

4. The maximum width of the detection portion in a width direction perpendicular to the longitudinal direction is equal to the maximum width of the adjustment portion. The position detection device according to claim 3 .

5. the excitation coil and the detection coil are formed on a single substrate; The position detection device according to any one of claims 1 to 4.

6. a second detection coil having a shape formed by combining a pair of curved portions is formed on the substrate; a phase of a change in the magnitude of the induced voltage induced in the second detection coil while the shaft moves from the moving end on one axial side to the moving end on the other axial side differs by 90° from a phase of a change in the magnitude of the induced voltage induced in the detection coil; The position detection device according to claim 5 .

7. The shaft is a rack shaft of a vehicle steering device. The position detection device according to claim 1 .

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