Position detection system and detector

Abstract

To provide a position detection system characterized in that although a detector that detects a position of a rack shaft is located in the vicinity of the rack shaft, the waterproofness of a rack housing is not impaired.SOLUTION: A stroke sensor 10 that detects a position of a rack shaft 11 which turns turning wheels 19 of a vehicle includes a rack housing 2 that accommodates the rack shaft 11, a substrate 3 that detects the position of the rack shaft 11 with respect to the rack housing 2, a support member 4 that supports the substrate 3 with respect to the rack housing 2, and a seal member 5 attached to the support member 4. A through hole 21 is formed in the rack housing 2 in order to penetrate an internal surface and periphery of the rack housing in the radial direction of the rack shaft 11. The support member 4 includes a support part 41 that is disposed in the through hole 21 and supports the substrate 3, and a stationary part 42 fixed to the rack housing 2. The seal member 5 is elastically in contact with an external surface 41a of the support part 41 and an internal surface 21a of the through hole 21.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a position detection device that detects the position of a rack shaft of a vehicle, and a detection device that detects a physical quantity. [Background technology]

[0002] The present applicant has proposed a position detection device for detecting the position of a vehicle rack shaft, as described in Patent Document 1. The position detection device described in Patent Document 1 includes a target made of a high magnetic permeability material or a high conductivity material fixed to the rack shaft, an excitation coil that generates an AC magnetic field, and a detection coil with which the magnetic flux of the AC magnetic field generated by the excitation coil intersects. The excitation coil and the detection coil are formed on a single substrate and extend along the axial direction of the rack shaft. The substrate is fixed to the cover of a rack housing that has a metal body and a resin cover. When the position of the target relative to the substrate changes as the rack shaft moves, the strength of the magnetic field detected by the detection coil changes. The substrate corresponds to the detector in the position detection device described in Patent Document 1.

[0003] Furthermore, Patent Document 2 describes the provision of a breather valve in the housing of a vehicle steering device to alleviate an increase in internal pressure. The breather valve is configured with a membrane that allows air or water vapor to pass through but blocks the passage of water droplets. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-174533 [Patent Document 2] Japanese Patent Application Publication No. 2019-044881 Summary of the Invention [Problem to be solved by the invention]

[0005] It is desirable to prevent moisture from entering the rack housing as much as possible to prevent rust, etc. Also, even if a breathing valve is provided in the steering device, as in the case of Patent Document 2, it is desirable to prevent water droplets, etc., from adhering to the detector due to water vapor that has passed through the breathing valve and entered the housing.

[0006] The present invention has been made in consideration of the above circumstances, and aims to achieve at least one of the following first to third objects. The first object is to provide a position detection device that can position a detector that detects the position of a rack shaft close to the rack shaft without compromising the waterproof properties of the rack housing. The second object is to provide a position detection device that can prevent water droplets, etc., caused by water vapor that has passed through a breathing valve and entered the housing from adhering to the detector. The third object is to provide a position detection device and a detection device that can prevent the removal of a seal member that is arranged between the inner surface of a through-hole formed in a mounting member such as a rack housing and the outer surface of a support member that supports the detector. [Means for solving the problem]

[0007] The present invention aims to solve the above-mentioned problems and provides a position detection device that detects the position of a rack shaft that steers the steered wheels of a vehicle by moving in the axial direction, the position detection device comprising: a cylindrical rack housing that accommodates the rack shaft; a detector that detects the position of the rack shaft relative to the rack housing; a support member that supports the detector relative to the rack housing; and a seal member attached to the support member, wherein the rack housing has a through hole that passes between its inner and outer peripheral surfaces in the radial direction of the rack shaft, the support member has a support part that is disposed within the through hole and supports the detector, and a fixing part that is fixed to the rack housing, and the seal member is in elastic contact with the outer surface of the support part and the inner surface of the through hole.

[0008] In addition, with the aim of solving the above-mentioned problems, the present invention provides a detection device comprising: a support member having a tubular portion that is accommodated in a through hole formed through a member to be attached; a detector that is accommodated in the accommodation space of the tubular portion and supported by the support member; a sealing member interposed between the inner surface of the through hole and the outer surface of the support member; and a sealing member attached to the end of the tubular portion and sealing the accommodation space, wherein the sealing member prevents the sealing member from coming off the tubular portion. [Effects of the Invention]

[0009] According to the present invention, at least one of the above first to third objects can be achieved. [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] FIG. 2 is a cross-sectional view showing a cross section of the steering device taken along line AA in FIG. [Figure 3] FIG. 2 is a perspective view of a detector, a rack shaft, and a detector attached to a rack housing. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] 4(a) and 4(b) are cross-sectional views taken along lines BB and CC in FIG. [Figure 7] FIG. 4 is a cross-sectional view taken along line DD in FIG. [Figure 8] 1A is a plan view showing an example of a wiring pattern of a first wiring layer and a third wiring layer of a substrate, and FIG. 1B is a plan view showing an example of a wiring pattern of a second wiring layer and a fourth wiring layer of a substrate. [Figure 9] FIG. 2 is a plan view showing the wiring patterns of a first wiring layer, a second wiring layer, a third wiring layer, and a fourth wiring layer of the substrate superimposed on each other. [Figure 10]10(a) and 10(b) show the states before and after laser welding the support member and the sealing member. [Figure 11] FIG. 4 is a cross-sectional view showing a sealing member in a natural state where no external force is applied. [Figure 12] FIG. 10 is a cross-sectional view of a hub unit equipped with a detection device according to a second embodiment. [Figure 13] 1(a) is a cross-sectional view of the detection device and its surroundings, and FIG. 1(b) is a partially enlarged view of FIG. [Figure 14] FIG. 4 is a perspective view showing an end of a cylindrical portion of a support member and a sealing member. DETAILED DESCRIPTION OF THE INVENTION

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

[0012] As shown in FIG. 1, the steering device 1 includes a stroke sensor 10, a rack shaft 11, ball joints 12 provided at both ends of the rack shaft 11, a tie rod 13 connected to the rack shaft 11 via the ball joints 12, a worm reduction mechanism 14 having a pinion gear 141 meshed with rack teeth 111 of the rack shaft 11, an electric motor 15 that applies axial moving force to the rack shaft 11 via the worm reduction mechanism 14, a steering wheel 16 operated by a driver, a steering angle sensor 17 that detects the steering angle of the steering wheel 16, and a steering control device 18 that controls the electric motor 15 based on the steering angle detected by the steering angle sensor 17. The rack shaft 11 steers left and right steerable wheels 19 (front wheels) by moving in the axial direction. The stroke sensor 10 detects the position of the rack shaft 11 in the vehicle width direction.

[0013] The rack shaft 11 is housed in a cylindrical rack housing 2 fixed to the vehicle body and is supported by a pair of rack bushings 201 arranged at both ends of the rack housing 2. In FIG. 1 , the rack housing 2 is indicated by a two-dot chain line, and the rack shaft 11 and worm reduction mechanism 14 inside it are indicated by solid lines. The rack housing 2 is provided with a breather valve 202 that allows air and water vapor to pass between the inside and outside of the rack housing 2 but blocks the passage of water droplets. The worm reduction mechanism 14 has a worm wheel 142 and a worm gear 143, and a pinion gear 141 is fixed to the worm wheel 142. The worm gear 143 is fixed to a motor shaft 151 of the electric motor 15.

[0014] The electric motor 15 generates torque by a motor current supplied from the steering control device 18, and rotates a worm wheel 142 and a pinion gear 141 via a worm gear 143. When the pinion gear 141 rotates, the rack shaft 11 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 19 are steered. The rack shaft 11 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 11 can move in the vehicle width direction is indicated by a double-headed arrow.

[0015] Fig. 2 is a cross-sectional view of the steering device 1 taken along line AA in Fig. 1. The stroke sensor 10 includes a detection body 110 fixed to the rack shaft 11, a rack housing 2, a substrate 3 serving as a detector for detecting the position of the rack shaft 11 relative to the rack housing 2, a metal plate 101 arranged parallel to the substrate 3, a support member 4 supporting the substrate 3 relative to the rack housing 2, a seal member 5 attached to the support member 4, a sealing member 6 sealing the substrate 3, a power supply unit 71, and a calculation unit 72 (see Fig. 1). As shown in Fig. 1, the substrate 3, the power supply unit 71, and the calculation unit 72 are connected by a cable 73 having a connector 731 attached to one end. The substrate 3, the metal plate 101, the support member 4, the seal member 5, and the sealing member 6 constitute a detection unit 100 of the stroke sensor 10.

[0016] Fig. 3 is a perspective view of the detection unit 100, rack shaft 11, and detection body 110 attached to the rack housing 2. Figs. 4 and 5 are exploded perspective views of the detection unit 100. Figs. 6(a) and 6(b) are cross-sectional views taken along lines BB and CC in Fig. 3. Fig. 7 is a cross-sectional view taken along line DD in Fig. 3.

[0017] The rack housing 2 is made of die-cast aluminum alloy, and has an accommodation hole 20 formed therein to accommodate the rack shaft 11. The rack housing 2 also has a through hole 21 formed therein that penetrates between the inner and outer peripheral surfaces along the radial direction of the rack shaft 11. The through hole 21 penetrates between the inner peripheral surface 2a and the outer peripheral surface 2b of the accommodation hole 20 in the rack housing 2. A portion of the outer peripheral surface 2b of the rack housing 2 forms a flat mounting surface 2c for mounting the support member 4. The penetrating direction of the through hole 21 is perpendicular to the mounting surface 2c and the central axis C of the rack housing 2.

[0018] The rack shaft 11 is a shaft-shaped member made of steel such as carbon steel, and the detection body 110 is attached to the outer peripheral surface 11a of the rack shaft 11 by, for example, welding. The detection body 110 is made of a material having a higher magnetic permeability than the rack shaft 11 or a material having a higher electrical conductivity than the rack shaft 11. When using a material having a higher magnetic permeability than the rack shaft 11 as the detection body 110, it is desirable to use a magnetic material such as ferrite, which has a high electrical resistance and is less likely to generate eddy currents. When using a material having a higher electrical conductivity than the rack shaft 11 for the detection body 110, it is possible to use a metal containing aluminum or copper as the main component, for example. The detection body 110 may be formed integrally with the rack shaft 11 as a part of the rack shaft 11.

[0019] The stroke sensor 10 detects the position of the rack shaft 11 based on the position of the detection body 110. The detection body 110 is attached in a position facing the detection unit 100 throughout the entire range R1 over which the rack shaft 11 can move in the vehicle width direction, but in FIG. 3, for the sake of explanation, the detection body 110 is shifted from the position facing the detection unit 100. The surface 110a of the detection body 110 facing the detection unit 100 is flat. In this embodiment, the magnetic action of the detection body 110 is utilized to detect the position of the detection body 110 by a substrate 3 serving as a detector. Next, the configuration of the substrate 3 will be described.

[0020] As shown in FIG. 2, the substrate 3 is a four-layer substrate having, from the front surface 3a facing the detection body 110 toward the back surface 3b, a first wiring layer 301, a second wiring layer 302, a third wiring layer 303, and a fourth wiring layer 304. Between the first wiring layer 301 and the second wiring layer 302, between the second wiring layer 302 and the third wiring layer 303, and between the third wiring layer 303 and the fourth wiring layer 304, base materials 30 made of a dielectric material such as FR4 (glass fiber impregnated with epoxy resin and subjected to a thermosetting treatment) are disposed. The first wiring layer 301 and the fourth wiring layer 304, which are outer layers, are covered with an electrically insulating resist film 300. Wiring patterns are formed on the first wiring layer 301, the second wiring layer 302, the third wiring layer 303, and the fourth wiring layer 304, respectively, and the wiring patterns of these layers are connected at multiple locations on the substrate 3 by vias 35.

[0021] FIG. 8(a) is a plan view showing an example of the wiring patterns of the first wiring layer 301 and the third wiring layer 303 of the substrate 3. FIG. 8(b) is a plan view showing an example of the wiring patterns of the second wiring layer 302 and the fourth wiring layer 304 of the substrate 3. FIG. 9 is a plan view showing the wiring patterns of the first wiring layer 301, the second wiring layer 302, the third wiring layer 303, and the fourth wiring layer 304 of the substrate 3 superimposed on each other. In FIGS. 8(a), 8(b), and 9, the wiring patterns of the third wiring layer 303 and the fourth wiring layer 304 are shown in light colors. In addition, in FIGS. 8(a), 8(b), and 9, the dimension of the width direction (vertical direction in the drawing) of the substrate 3 is shown enlarged relative to the dimension in the longitudinal direction (horizontal direction in the drawing).

[0022] The substrate 3 has an excitation coil 31 that generates a magnetic field, and a first detection coil 32 and a second detection coil 33 that detect the magnetic field generated by the excitation coil 31. The excitation coil 31 is formed in a first wiring layer 301 and a third wiring layer 303 along the periphery of the substrate 3. The first detection coil 32 is formed in the first wiring layer 301 and the third wiring layer 303. The second detection coil 33 is formed in a second wiring layer 302 and a fourth wiring layer 304. One longitudinal end of the substrate 3 is provided with a through-hole group 34 consisting of a plurality of through-holes 341 to 346 to which connector terminals 102 (see FIGS. 4 and 5) are connected for connection to the power supply unit 71 and the calculation unit 72 via a cable 73 and a connector 731 (see FIG. 1).

[0023] The first detection coil 32 is made up of a pair of curved portions 321, 322 that form a sine wave when viewed from the front surface 3a of the substrate 3. The second detection coil 33 is made up of a pair of curved portions 331, 332 that form a cosine wave when viewed from the front surface 3a of the substrate 3. The excitation coil 31, the first detection coil 32, and the second detection coil 33 are each formed in a loop shape, and their starting and ending ends are connected to through holes 341 to 346 of the through hole group 34. The pair of curved portions 321, 322 of the first detection coil 32 are connected by vias 35 at the other end of the substrate 3 in the longitudinal direction. The pair of curved portions 331, 332 of the second detection coil 33 are also connected by vias 35 at the other end of the substrate 3 in the longitudinal direction.

[0024] The excitation coil 31 generates an AC magnetic field in a direction perpendicular to the substrate 3 by using a high-frequency current supplied from the power supply unit 71 via a cable 73. The magnetic flux of the AC magnetic field generated by the excitation coil 31 also interlinks with the detection body 110. The magnetic flux interlinking with the detection body 110 affects the intensity distribution of the magnetic flux on the substrate 3. If the detection body 110 is made of a high-permeability material, the magnetic flux flows concentrated in the detection body 110, increasing the magnetic flux density in the portion corresponding to the detection body 110. Furthermore, if the detection body 110 is made of a high-conductivity material, eddy currents generated in the detection body 110 reduce the magnetic flux density in the portion corresponding to the detection body 110.

[0025] The spacing between the pair of curved portions 321, 322 of the first detection coil 32 in the width direction of the substrate 3 and the spacing between the pair of curved portions 331, 332 of the second detection coil 33 vary depending on the longitudinal position of the substrate 3, and therefore the strength of the magnetic field detected by the first detection coil 32 and the second detection coil 33 changes depending on the positions of the rack shaft 11 and the detection body 110.

[0026] The first and second detection coils 32 and 33 output output signals, which are voltages induced by the AC magnetic field generated by the excitation coil 31, to the calculation unit 72 via the cable 73. The calculation unit 72 calculates the position of the detection body 110 based on the output signals and transmits the calculation result to the steering control device 18. The magnitudes of the voltages induced in the first and second detection coils 32 and 33 change within a range of less than one cycle while the rack shaft 11 moves from one axial end to the other axial end. Furthermore, due to the difference in shape between the first and second detection coils 32 and 33, the phases of the changes in the magnitudes of the voltages induced in the first and second detection coils 32 and 33 as the rack shaft 11 moves are different by 90°. Therefore, the stroke sensor 10 can detect the absolute position of the rack shaft 11 throughout the entire range R1 in which the rack shaft 11 can move axially.

[0027] Furthermore, a plurality of mounting holes 36 for fixing to the support member 4 are formed in the substrate 3, penetrating between the front surface 3a and the back surface 3b. Each mounting hole 36 is formed in the center of the substrate 3 in the width direction at a position that does not overlap with the wiring patterns of the excitation coil 31, the first detection coil 32, and the second detection coil 33.

[0028] The metal plate 101 is made of, for example, iron and is ferromagnetic and conductive. By arranging the metal plate 101 parallel to the substrate 3, the magnetic coupling between the excitation coil 31 and the first and second detection coils 32 and 33 is improved, and the influence of external electromagnetic waves can be suppressed. A plurality of mounting holes 101a are formed in the metal plate 101. Each mounting hole 101a penetrates the metal plate 101 in the thickness direction.

[0029] The support member 4 is made of an electrically insulating resin, and integrally includes a support portion 41 that supports the substrate 3 and the metal plate 101, a fixing portion 42 that is fixed to the rack housing 2, and a connector holding portion 43 that holds the connector 731. In this embodiment, the support member 4 is provided with four fixing portions 42, and a metal collar 103 is in-mold formed on each fixing portion 42. The fixing portions 42 are fixed to the rack housing 2 by threading bolts 104 (see FIGS. 3 and 6) that are inserted through the collars 103 into bolt holes 22 formed in the rack housing 2.

[0030] At least a portion of the support portion 41 is disposed within the through-hole 21 of the rack housing 2. The seal member 5 is in elastic contact with the outer surface 41a of the support portion 41 and the inner surface 21a of the through-hole 21. Hereinafter, the side of the through-hole 21 facing the rack shaft 11 will be referred to as the back side, and the opposite side will be referred to as the outside. The substrate 3 is disposed on the back side of the through-hole 21 relative to the metal plate 101.

[0031] The metal plate 101 is in-molded into the support portion 41 of the support member 4. The resin of the support member 4 fills the multiple mounting holes 101a of the metal plate 101 when the support member 4 is molded. An inner rib 411 is formed in a portion of the support portion 41 that is deeper than the metal plate 101 into the through hole 21. An outer rib 412 is formed in a portion of the support portion 41 that is outer than the metal plate 101 into the through hole 21. The inner rib 411 and the outer rib 412 contribute to reducing the weight and increasing the rigidity of the support member 4. The surface of the metal plate 101 that is deeper than the through hole 21 is exposed through the gaps in the inner rib 411, but the outer surface of the metal plate 101 outside the through hole 21 is covered with the resin of the support member 4 for rust prevention and waterproofing and is not exposed to the outside.

[0032] The substrate 3 is supported by the end of the support portion 41 on the rack shaft 11 side. Specifically, the back surface 3b of the substrate 3 is in contact with the inner rib 411, and the substrate 3 is supported by multiple support protrusions 413 that protrude from the inner rib 411 toward the back of the through-hole 21. Before the substrate 3 is attached to the support member 4, each support protrusion 413 is cylindrical, as shown in FIG. 5. When attaching the substrate 3 to the support member 4, the multiple support protrusions 413 are inserted into the multiple mounting holes 36 of the substrate 3, and then the tips of the support protrusions 413 are heated, and the melted portions are pressed against the surface 3a of the substrate 3 to form disk-shaped locking portions 413a (see FIG. 6). The locking portions 413a prevent the substrate 3 from slipping off the support protrusions 413, and the substrate 3 is supported by the support portion 41. In addition, the support portion 41 is formed with a frame portion 414 that surrounds the substrate 3.

[0033] The sealing member 6 is made of an electrically insulating resin like the support member 4, and hermetically seals the substrate 3 between it and the support part 41 of the support member 4. That is, the accommodation space 410 that accommodates the substrate 3 is sealed by the sealing member 6. This prevents water droplets formed when the water vapor condenses onto the substrate 3, even if water vapor enters the rack housing 2 from the breathing valve 202, for example. In this embodiment, the support member 4 and the sealing member 6 are joined by laser welding.

[0034] The sealing member 6 has a flat detection element facing surface 6a that faces the detection element 110. As shown in FIGS. 4 and 6(b), recesses 60 are formed in multiple locations on the substrate facing surface 6b of the sealing member 6 that faces the substrate 3 to prevent interference with the locking portions 413a of the support protrusions 413. The sealing member 6 also has an annular protrusion 61 that is disposed inside the frame portion 414 of the support member 4. The annular protrusion 61 regulates misalignment of the sealing member 6 with respect to the support member 4 during laser welding. Hereinafter, the outer portion of the annular protrusion 61 of the sealing member 6 will be referred to as an outer edge portion 62.

[0035] 10(a) and (b) show the frame portion 414 of the support portion 41 of the support member 4 and the state of the peripheral portion of the seal member 5 before and after laser welding. The front end surface 414a of the frame portion 414 is located deeper in the through hole 21 than the substrate 3. An accommodation space 410 that accommodates the substrate 3 is formed inside the frame portion 414. In addition, the support portion 41 is formed with a protrusion 415 that protrudes further deeper into the through hole 21 from the front end surface 414a of the frame portion 414. The frame portion 414 and the protrusion 415 are formed in a ring shape so as to surround the substrate 3.

[0036] 10(a), laser welding is performed by irradiating the sealing member 6 with laser light Lr from the detection-object-facing surface 6a side while pressing the outer edge portion 62 of the sealing member 6 against the tip surface 415a of the protrusion 415 of the support member 4. The laser light Lr passes through the outer edge portion 62 of the sealing member 6 and strikes the tip surface 415a of the protrusion 415, melting the protrusion 415 and a part of the outer edge portion 62 of the sealing member 6 that is in contact with the protrusion 415. That is, in this embodiment, the sealing member 6 is made of a light-transmitting resin that transmits the laser light Lr, and the support member 4 is made of a light-absorbing resin that absorbs the laser light Lr.

[0037] In this laser welding, the protrusion 415 of the support member 4 and the outer edge portion 62 of the sealing member 6 are joined over the entire periphery by relative movement between the support member 4 and the sealing member 6 and the laser torch 74. When the resin melted by the laser light Lr solidifies, the support member 4 and the sealing member 6 are welded together at the solidified portion. As shown in FIG. 10(b), the height of the protrusion 415 after laser welding is lower than the height of the protrusion 415 before laser welding.

[0038] To ensure reliable laser welding, it is desirable that the support member 4 and the sealing member 6 are made of the same type of resin. For example, if the support member 4 is made of nylon 66, it is desirable that the sealing member 6 is also made of nylon 66, and if the support member 4 is made of PBT (polybutylene terephthalate), it is desirable that the sealing member 6 is also made of PBT. The support member 4 can be made light-absorbent by blending it with, for example, carbon black.

[0039] An outer surface 41a of the support portion 41 of the support member 4 has an elastic contact surface 41b with which the seal member 5 elastically contacts, an opposing surface 41c that faces the inner surface 21a of the through hole 21 of the rack housing 2 at a position closer to the inner surface 21a of the through hole 21 than the elastic contact surface 41b, and a step surface 41d between the elastic contact surface 41b and the opposing surface 41c. The step surface 41d is perpendicular to the elastic contact surface 41b and the opposing surface 41c and is oriented toward the back side of the through hole 21. The seal member 5 is disposed between the step surface 41d and an outer edge portion 62 of the sealing member 6, and is prevented from coming off the support portion 41 by the outer edge portion 62 of the sealing member 6.

[0040] 11 is a cross-sectional view showing the seal member 5 alone in its natural state when no external force is acting on it. The seal member 5 is made of, for example, silicone rubber, and is attached to the outer periphery of the support portion 41 of the support member 4 and is placed inside the through hole 21 of the rack housing 2. The seal member 5 is annular and surrounds the outer periphery of the support portion 41, and has multiple inner circumferential lips 51 and multiple outer circumferential lips 52. The tip ends of the multiple inner circumferential lips 51 and the multiple outer circumferential lips 52 are rounded. When the support portion 41 is placed inside the through hole 21 of the rack housing 2, the multiple inner circumferential lips 51 elastically contact the elastic contact surface 41b of the support portion 41, and the multiple outer circumferential lips 52 elastically contact the inner surface 21a of the through hole 21.

[0041] In FIG. 11, the width dimension of the sealing member 5 in its natural state is indicated by W. A distance G1 (see FIG. 10(b)) between the stepped surface 41d of the support portion 41 and the outer edge portion 62 of the sealing member 6 after laser welding in the penetration direction of the through hole 21 is wider than the width W of the sealing member 5. Therefore, a gap is formed between one side surface 5a of the sealing member 5 and the stepped surface 41d of the support portion 41, or between the other side surface 5b of the sealing member 5 and the outer edge portion 62 of the sealing member 6. With this configuration, the sealing member 5 is not compressed between the stepped surface 41d of the support portion 41 and the outer edge portion 62 of the sealing member 6, and it is possible to prevent the outer edge portion 62 of the sealing member 6 from being separated from the protrusion 415 of the support member 4 due to the restoring force of the sealing member 5.

[0042] 10(a), T1 denotes the height of the protrusion 415 before laser welding, and D denotes the minimum distance between the elastic surface 41b of the support portion 41 and the tip surface 415a of the protrusion 415 in a direction perpendicular to the penetration direction of the through hole 21. In FIG. 11, T2 denotes the thickness of the inner circumferential lip 51 at the position of the minimum distance D shown in FIG. 10(a), where the distance in the thickness direction of the seal member 5 from the tip end 51a of the inner circumferential lip 51 closest to the sealing member 6 among the multiple inner circumferential lips 51 of the seal member 5 is the minimum distance D. T2 is thicker than T1, which prevents the inner circumferential lip 51 from being pinched between the frame portion 414 of the support portion 41 and the outer edge portion 62 of the sealing member 6 during laser welding.

[0043] (Effects of the first embodiment) According to the first embodiment described above, the waterproofing of the rack housing 2 can be prevented by the sealing member 5 while the substrate 3 that detects the position of the rack shaft 11 is disposed close to the rack shaft 11. Furthermore, since the sealing member 6 seals the substrate 3 between it and the support part 41 of the support member 4, it is possible to prevent water droplets and the like caused by water vapor that has passed through the breathing valve 202 and entered the rack housing 2 from adhering to the substrate 3. Furthermore, the sealing member 6 can prevent the sealing member 5 from coming off toward the back side of the through-hole 21.

[0044] [Second embodiment] Next, a second embodiment of the present invention will be described. Fig. 12 is a cross-sectional view showing a hub unit 9 equipped with a detection device 8 according to the second embodiment. Fig. 13(a) is a cross-sectional view of the detection device 8 and its surrounding area. Fig. 13(b) is a partially enlarged view of Fig. 13(a). The hub unit 9 is attached to a knuckle that constitutes a suspension system of a vehicle, and rotatably supports a wheel. The detection device 8 detects the rotational speed of the wheel.

[0045] The hub unit 9 comprises a hub wheel 91 having a wheel mounting flange 911, a plurality of hub bolts 92 fixed to the wheel mounting flange 911 by press fitting, a pair of inner rings 93, 94 attached to the outer periphery of the hub wheel 91, an outer ring 95 arranged on the outer periphery of the pair of inner rings 93, 94, a plurality of rolling elements 96 and a sealing member 97 arranged between the pair of inner rings 93, 94 and the outer ring 95, a retainer 98 that holds the plurality of rolling elements 96, and a pulser ring 99 attached to the inner ring 93.

[0046] The outer ring 95 has a fixing flange 951 for fixing to the knuckle. The detection device 8 is partially inserted into a through hole 950 formed in the outer ring 95 and fixed to the outer ring 95 with a bolt 90. The outer ring 95 is a mounting member to which the detection device 8 is attached. The through hole 950 passes radially through the outer ring 95 and opens to an inner circumferential surface 95a and an outer circumferential surface 95b of the outer ring 95.

[0047] A plurality of magnetic poles consisting of N and S poles are arranged alternately in the circumferential direction on the outer peripheral surface of the pulser ring 99. The detector 8 detects the rotation of the wheel by the change in the magnetic field caused by the rotation of the pulser ring 99, and outputs a detection signal to an ABS (Antilock Brake System) controller (not shown).

[0048] The detection device 8 includes a support member 81 having a cylindrical tubular portion 811 that is housed in a through hole 950 formed in the outer ring 95, a detector 82 that is housed in the housing space 80 of the tubular portion 811 and supported by the support member 81, a seal member 83 that is interposed between an inner surface 950a of the through hole 950 and an outer surface 811a of the tubular portion 811 of the support member 81, a seal member 84 that is attached to an end of the tubular portion 811 and seals the housing space 80, and a cable 85 that has a plurality of electric wires 851, 852 connected to the detector 82. The seal member 83 is prevented from coming off the tubular portion 811 by the seal member 84.

[0049] The support member 81 is a resin molded body formed by injection molding, and has a cylindrical portion 811, a flange portion 812 for fixing to the outer ring 95, and a cable holding portion 813 for holding the cable 85. A metal collar 86 is insert-molded into the flange portion 812, and the bolt 90 inserted through the collar 86 is threaded into a bolt hole 952 formed in the outer ring 95, thereby fixing the support member 81 to the outer ring 95.

[0050] The detector 82 is composed of a substrate 821 on which a wiring pattern (not shown) is formed, and a magnetic field detection element 822 mounted on the substrate 821. The magnetic field detection element 822 detects the magnetic field of the magnetic pole of the pulser ring 99. Electric wires 851 and 852 of the cable 85 are connected to electrodes formed on the substrate 821 by, for example, soldering, and transmit a detection signal of the magnetic field detection element 822. The cable 85 has a sheath 853 that houses the electric wires 851 and 852. The sheath 853 is in liquid-tight contact with the cable holding portion 813 of the support member 81.

[0051] FIG. 14 is a perspective view showing the end of the cylindrical portion 811 of the support member 81 and the sealing member 84. An annular protrusion 810 is provided on the end of the cylindrical portion 811, and the sealing member 84 is welded to this protrusion 810. The sealing member 84 is made of resin and is formed in a disk shape with a diameter smaller than the inner diameter of the through-hole 950. As in the first embodiment, laser welding can be used to weld the protrusion 810 of the support member 81 to the sealing member 84, in which laser light that has passed through the sealing member 84 is irradiated onto the tip surface 810a of the protrusion 810. The protrusion 810 is welded to the sealing member 84 around the entire circumference. The sealing member 84 is made of a light-transmitting resin, and the support member 81 is made of a light-absorbing resin.

[0052] A pair of grooves 800 for supporting a substrate 821 are formed in the cylindrical portion 811. The grooves 800 are recessed from the inner peripheral surface 80a of the cylindrical portion 811 and extend in the axial direction of the cylindrical portion 811. The substrate 821 has a rectangular shape with its long side extending in the axial direction of the cylindrical portion 811, and both ends in the short side direction are accommodated in the pair of grooves 800 and are prevented from slipping out of the grooves 800 by sealing members 84.

[0053] An outer surface 811a of the cylindrical portion 811 has an elastic contact surface 811b with which the seal member 83 elastically contacts, an opposing surface 811c that faces the inner surface 950a of the through hole 950 at a position closer to the inner surface 950a of the through hole 950 than the elastic contact surface 811b, and a step surface 811d between the elastic contact surface 811b and the opposing surface 811c. The seal member 83 has a plurality of inner circumferential lips 831 and a plurality of outer circumferential lips 832. The plurality of inner circumferential lips 831 elastically contact the elastic contact surface 811b, and the plurality of outer circumferential lips 832 elastically contact the inner surface 950a of the through hole 950.

[0054] In the axial direction of the cylindrical portion 811, the sealing member 83 is disposed between the stepped surface 811d and the sealing member 84. A distance G2 between the stepped surface 811d and the sealing member 84 in the axial direction of the cylindrical portion 811 is wider than the width of the sealing member 83 in the same direction in its natural state. This prevents the sealing member 83 from being compressed between the stepped surface 811d of the cylindrical portion 811 and the sealing member 84, and prevents the sealing member 84 from being separated from the protrusion 810 of the support member 81 due to the restoring force of the sealing member 83.

[0055] (Effects of the second embodiment) According to the second embodiment described above, the housing space 80 for the detector 82 in the support member 81 can be sealed by the sealing member 84, thereby preventing the intrusion of moisture and the like into the housing space 80. In addition, the sealing member 84 can prevent the seal member 83 from coming off the support member 81, thereby preventing the intrusion of moisture and the like into the inside of the outer ring 95.

[0056] (Summary of the embodiment) Next, the technical ideas grasped from the first and second embodiments explained above will be described using the reference numerals and symbols in the first and second embodiments. However, the reference numerals in the following description do not limit the components in the claims to the members and symbols specifically shown in the embodiments.

[0057] [1] A position detection device (stroke sensor 10) for detecting the position of a rack shaft (11) that steers steerable wheels (19) of a vehicle by moving in the axial direction, the position detection device comprising: a cylindrical rack housing (2) that accommodates the rack shaft (11); a detector (substrate 3) that detects the position of the rack shaft (11) relative to the rack housing (2); a support member (4) that supports the detector (3) relative to the rack housing (2); and a seal member (5) attached to the support member (4). a through hole (21) formed in the rack housing (2) and penetrating between the inner and outer circumferential surfaces along the radial direction of the rack shaft (11); the support member (4) has a support part (41) disposed in the through hole (21) and supporting the detector (3), and a fixing part (42) fixed to the rack housing (2); and the seal member (5) is in elastic contact with an outer surface (41 a) of the support part (41) and an inner surface (21 a) of the through hole (21).

[0058] [2] The position detection device (10) described in [1] above, wherein the detector (3) is supported at the end of the support portion (41) on the rack shaft (11) side, and further includes a sealing member (6) that seals the detector (3) between the support portion (41).

[0059] [3] The position detection device (10) described in [2] above, wherein the support portion (41) has an elastic contact surface (41b) with which the sealing member (5) elastically contacts, an opposing surface (41c) that faces the inner surface (21a) of the through hole (21) at a position closer to the inner surface (21a) of the through hole (21) than the elastic contact surface (41b), and a step surface (41d) between the elastic contact surface (41b) and the opposing surface (41c), and the sealing member (5) is disposed between the step surface (41d) and the sealing member (6), and the sealing member (6) prevents the sealing member (5) from coming off the support portion (41).

[0060] [4] The position detection device (10) according to [3] above, wherein a distance (G1) between the step surface (41d) and the sealing member (6) in the penetration direction of the through hole (21) is wider than a width (W) in the same direction of the sealing member (5) in its natural state.

[0061] [5] The position detection device (10) described in [1] to [4] above, wherein the detector (3) has an excitation coil (31) that generates a magnetic field and detection coils (32, 33) that detect the magnetic field generated by the excitation coil (31), and is a substrate (3) configured so that the strength of the magnetic field detected by the detection coils (32, 33) changes depending on the position of the rack shaft (11), and further includes a metal plate (101) supported by the support member (4) and arranged parallel to the substrate (3).

[0062] [6] A detection device (8) comprising: a support member (81) having a cylindrical portion (811) accommodated in a through hole (950) formed through an attachment member (outer ring 95); a detector (82) accommodated in an accommodation space (80) of the cylindrical portion (811) and supported by the support member (81); a sealing member (83) interposed between an inner surface (950a) of the through hole (950) and an outer surface (811a) of the support member (81); and a sealing member (84) attached to an end of the cylindrical portion (811) and sealing the accommodation space (80), wherein the sealing member (84) prevents the sealing member (83) from coming off the cylindrical portion (811).

[0063] [7] The detection device (8) described in [6] above, wherein the cylindrical portion (811) has an elastic contact surface (811b) with which the sealing member (83) elastically contacts, an opposing surface (811c) that faces the inner surface (950a) of the through hole (950) at a position closer to the inner surface (950a) of the through hole (950) than the elastic contact surface (811b), and a step surface (811d) between the elastic contact surface (811b) and the opposing surface (811c), and the sealing member (83) is arranged between the step surface (811d) and the sealing member (84).

[0064] [8] The detection device (8) according to [7] above, wherein a gap (G2) between the step surface (811d) and the sealing member (84) in the axial direction of the cylindrical portion (811) is wider than the width of the sealing member (83) in the same direction in its natural state.

[0065] Although the first and second embodiments of the present invention have been described above, the invention according to the claims is not limited to these first and second embodiments. It should be noted that not all of the combinations of features described in the first and second embodiments are necessarily essential to the means for solving the problems of the invention. The present invention can be modified and implemented as appropriate without departing from the spirit of the invention, and the following modifications are possible, for example:

[0066] In the above first and second embodiments, the sealing members 6, 84 are welded to the support members 4, 81 by laser welding. However, this is not a limitation, and they may be welded by, for example, ultrasonic welding. Furthermore, in the above first embodiment, the first detection coil 32 and the second detection coil 33 of the substrate 3 as the detector detect a magnetic field, and in the above second embodiment, the magnetic field detection element 822 of the detector 82 detects a magnetic field. However, the physical quantity detected by the detector is not limited to a magnetic field and may be, for example, temperature, pressure, or acceleration. Furthermore, in the above second embodiment, the detection device 8 is applied to the hub unit 9. However, the application of the detection device 8 is not limited to this, and the detection device 8 can be applied to various devices and equipment. [Explanation of symbols]

[0067] 10... Stroke sensor (position detection device) 101... Metal plate 11...Rack shaft 19...Steering wheel 2...Rack housing 21...Through hole 3... Substrate (detector) 4... Support member 41...Support part 41a...Outer surface 41b…Bullet contact surface 41c…Opposing surface 41d...Step surface 5...Sealing member 6...Sealing member 8...Detection device 811... Cylindrical portion 811a... Outer surface 811b…Bullet contact surface 811c…Opposing surface 811d...Step surface 82...Detector 83...Sealing member 84...Sealing member 95...Outer ring (mounted member) 950...Through hole 950a...Inner surface G1, G2...Spacing W…width

Claims

1. A position detection device that detects the position of a rack shaft that steers the steered wheels of a vehicle by moving in the axial direction, a cylindrical rack housing that accommodates the rack shaft; a detector that detects the position of the rack shaft relative to the rack housing; a support member that supports the detector relative to the rack housing; and a seal member attached to the support member, a through hole is formed in the rack housing, the through hole passing through the rack housing between its inner and outer peripheral surfaces along the radial direction of the rack shaft; the support member has a support portion that is disposed in the through hole and supports the detector, and a fixing portion that is fixed to the rack housing, The sealing member is in elastic contact with an outer surface of the support portion and an inner surface of the through hole. Position detection device.

2. the detector is supported by an end of the support portion on the rack shaft side, The detector further includes a sealing member that seals the detector between the detector and the support portion. The position detection device according to claim 1 .

3. the support portion has an elastic contact surface with which the sealing member elastically contacts, an opposing surface that faces the inner surface of the through hole at a position closer to the inner surface of the through hole than the elastic contact surface, and a step surface between the elastic contact surface and the opposing surface, the sealing member is disposed between the step surface and the sealing member, The sealing member prevents the seal member from coming off the support portion. The position detection device according to claim 2 .

4. a distance between the step surface and the sealing member in a penetration direction of the through hole is wider than a width of the sealing member in the same direction in a natural state; The position detection device according to claim 3 .

5. the detector is a substrate having an excitation coil that generates a magnetic field and a detection coil that detects the magnetic field generated by the excitation coil, and configured such that the strength of the magnetic field detected by the detection coil changes depending on the position of the rack shaft; The device further includes a metal plate supported by the support member and arranged parallel to the substrate. The position detection device according to any one of claims 1 to 4.

6. a support member having a cylindrical portion that is accommodated in a through hole formed through the attached member; a detector accommodated in the accommodation space of the cylindrical portion and supported by the support member; a seal member interposed between an inner surface of the through hole and an outer surface of the support member; a sealing member attached to an end of the cylindrical portion and sealing the accommodation space, The sealing member is prevented from coming off the cylindrical portion by the sealing member. Detection device.

7. the cylindrical portion has an elastic contact surface with which the sealing member elastically contacts, an opposing surface that faces the inner surface of the through hole at a position closer to the inner surface of the through hole than the elastic contact surface, and a step surface between the elastic contact surface and the opposing surface, The sealing member is disposed between the step surface and the sealing member. The detection device according to claim 6.

8. a gap between the step surface and the sealing member in the axial direction of the cylindrical portion is wider than a width of the sealing member in the axial direction in a natural state; The detection device according to claim 7.

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