Vehicle steering system

Abstract

This vehicle steering device comprises: a rotating member having a male thread portion and a first cylindrical surface portion; a nut that moves in an X direction with respect to the rotating member in a non-rotating state; a first annular member inserted into the first cylindrical surface portion and movable in the X direction; a wave washer which abuts against the first annular member, thereby being able to elastically deform in the X direction; and a housing. The housing has: a holding portion that holds the elastic member; and a nut abutment portion which can abut against the nut when the nut moves and transmits, to the rotating member, a reaction force toward an X1 side that is generated when the nut abuts.

Description

Technical Field

[0001] The present disclosure relates to a vehicle steering device.

Background Art

[0002] In a steer-by-wire type vehicle steering device, the steering wheel and the steered wheels are mechanically disconnected. In this configuration, the steering reaction force is not transmitted from the steering mechanism including the steered wheels to the steering wheel. Therefore, a steering reaction force device and a stopper mechanism portion are provided on the steering shaft connected to the steering wheel.

[0003] The steering reaction force device applies a reaction force in the opposite direction to the rotation direction (steering direction) of the steering wheel to the steering wheel to give the driver a natural steering operation feeling. The steering reaction force device includes, for example, a motor and a reduction mechanism, and the steering reaction force generated by the motor is transmitted to the steering shaft via the reduction mechanism. The reduction mechanism has, for example, a worm shaft and a worm wheel, and the rotation of the motor is transmitted to the worm wheel via the worm shaft by the shaft teeth of the worm shaft meshing with the wheel teeth of the worm wheel.

[0004] Also, the steering wheel is connected to the steering shaft. The stopper mechanism portion conveys the limit range of the steering angle of the steered wheels to the driver. The stopper mechanism portion includes, for example, a rotating member connected to the steering shaft, a nut attached to the rotating member and linearly moving axially with respect to the rotating member, and a stopper portion that blocks the linear movement of the nut. When the linearly moving nut abuts against the stopper portion, the rotation of the rotating member stops, and accordingly, the rotation (steering) of the steering wheel via the steering shaft is also blocked. In this way, the rotation angle of the steering wheel is restricted.

[0005] Here, immediately after the linearly moving nut contacts the stopper, the motor of the steering reaction force device does not stop rotating immediately but continues to rotate for a short time due to inertia. As a result, force is applied to the meshing portion between the worm shaft and the worm wheel in the reduction mechanism, which may cause damage to the meshing portion. In Patent Document 1, to suppress such damage, the stopper portion that the nut contacts is made of an elastic material. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] German Patent No. 102020126785 Specification [Overview of the project] [Problems that the invention aims to solve]

[0007] However, in Patent Document 1, elastic members are arranged on both sides of the rotating member in the axial direction, which can lead to the stopper mechanism becoming longer in the axial direction, and consequently, the vehicle steering device becoming larger.

[0008] This disclosure has been made in view of the aforementioned issues and aims to provide a more compact steering device for vehicles. [Means for solving the problem]

[0009] To achieve the above objective, a steering device for a vehicle according to one embodiment is a steering device for a vehicle in which a steering wheel and a steering wheel are mechanically unconnected, and comprises a stopper mechanism that restricts the range of rotation angle of the steering wheel when the steering wheel is rotated, the stopper mechanism comprising a male screw portion having a male screw on its outer circumference, and a first cylindrical surface portion adjacent to one side of the male screw portion in the axial direction of the central axis, extending along the circumferential direction around the central axis and having a cylindrical surface with a diameter smaller than the outer diameter of the male screw portion, a rotating member that rotates circumferentially in accordance with the rotation of the steering wheel, and a nut disposed on the outer circumference of the rotating member, having a female screw on its inner circumference that meshes with the male screw, and in a non-rotating state, the rotating member The device comprises a nut that moves axially relative to the rotating member by rotation, a first annular member inserted into the first cylindrical surface of the rotating member and movable axially in contact with the nut or the male threaded portion, an elastic member positioned adjacent to one side in the axial direction relative to the first annular member and elastically deformable in the axial direction in contact with the first annular member, and a housing positioned on the outer circumference of the rotating member, the nut, the first annular member, and the elastic member, wherein the housing has a holding portion for holding the elastic member and a nut contact portion positioned opposite to the other side in the axial direction relative to the nut, which is able to contact the nut when the nut moves and transmits the reaction force directed toward one side in the axial direction generated when the nut contacts to the rotating member.

[0010] In a steer-by-wire steering system, a steering reaction force device is provided on the steering shaft connected to the steering wheel in order to apply a steering reaction force to the steering wheel in the opposite direction to the steering direction of the steering wheel. In addition, a stopper mechanism is provided to inform the driver of the limit range of the steering angle of the steering wheels. The stopper mechanism is provided to prevent the steering wheel from rotating beyond a certain angle, for example, to allow the driver to recognize the end contact position or to prevent the airbag harness connected to the steering wheel from breaking due to excessive rotation. The stopper mechanism comprises, for example, a rotating member connected to the steering shaft, a nut attached to the rotating member and moving linearly in the axial direction relative to the rotating member, and a stopper part that prevents the linear movement of the nut. When the linearly moving nut comes into contact with the stopper part, the rotation of the rotating member stops, and consequently, the rotation (steering) of the steering wheel is also prevented via the steering shaft.

[0011] Immediately after the linearly moving nut contacts the stopper, the motor of the steering reaction force device will continue to rotate for a short time due to inertia, which can cause force to be applied to the meshing portion between the worm shaft and worm wheel in the reduction mechanism, potentially leading to damage. Therefore, as mentioned above, Patent Document 1 uses an elastic member for the stopper portion that the nut contacts in order to suppress damage to the meshing portion. Specifically, since elastic members are arranged on both sides, one and the other, in the axial direction of the rotating member, the stopper mechanism becomes longer in the axial direction, which may lead to an increase in the size of the vehicle steering device.

[0012] In this disclosure, only one elastic member is provided. That is, an elastic member is provided on one side of the nut in the axial direction, and no elastic member is provided on the other side of the nut in the axial direction, so the number of elastic members is fewer than in Patent Document 1. Therefore, the axial distance of the stopper mechanism is shortened, and consequently, the steering device for vehicles can be made smaller. The following briefly explains how the stopper mechanism functions effectively even with only one elastic member.

[0013] First, in the first embodiment, when the nut moves linearly in one direction in the axial direction, the nut compresses the elastic member in the axial direction via the first annular member, causing the elastic member to elastically deform.

[0014] Next, in a second embodiment, when the nut moves linearly to the other side in the axial direction, the nut contacts the nut contact portion, and a reaction force is generated from the nut contact portion toward one side in the axial direction. This reaction force is transmitted to the male screw, and the rotating member moves toward one side in the axial direction. Subsequently, the first annular member compresses the elastic member in the axial direction, causing the elastic member to elastically deform.

[0015] Thus, in both the first mode in which the nut moves linearly in one axial direction and the second mode in which the nut moves linearly in the other axial direction, the impact when the first annular member or nut contact portion and the nut come into contact is absorbed by elastically deforming one elastic member. Therefore, as described above, in this disclosure, since the number of elastic members is smaller than in Patent Document 1, the axial distance of the stopper mechanism is shortened, and consequently, the steering device for vehicles can be miniaturized.

[0016] In a preferred embodiment, the rotating member has a second cylindrical surface portion adjacent to the other axial side of the male thread portion, extending circumferentially, and having a cylindrical surface with a diameter smaller than the outer diameter of the male thread portion, and the nut contact portion is a second annular member inserted into the second cylindrical surface portion.

[0017] In the second embodiment described above, when the nut moves linearly to the other side in the axial direction, the nut comes into contact with the second annular member, and a reaction force is generated from the second annular member toward one side in the axial direction. This reaction force is transmitted to the male screw, and the rotating member 31 moves toward one side in the axial direction. In this way, the second annular member functions properly as a nut contact point. Furthermore, if the second annular member is damaged, its function as a nut contact point can be easily restored by replacing it with a new one.

[0018] In a preferred embodiment, the elastic member has an annular shape extending along the circumferential direction, the rotating member has a cylindrical shape extending along the circumferential direction, the holding portion of the housing is provided with an annular through hole that penetrates axially and extends along the circumferential direction, the inner diameter of the elastic member is greater than or equal to the inner diameter of the rotating member, and the inner diameter of the through hole in the holding portion is greater than or equal to the inner diameter of the elastic member.

[0019] Therefore, by passing through the through hole and the inner circumference of the elastic member, components such as shafts extending in the axial direction can be fitted to the inner circumference of the rotating member.

[0020] In a desirable embodiment, the first annular member and the first cylindrical surface portion are movable relative to each other in the axial direction, and the second annular member and the second cylindrical surface portion are movable relative to each other in the axial direction.

[0021] In the first embodiment described above, the nut moves linearly to one side in the axial direction, pushing the first annular member and moving it to the other side in the axial direction, thereby compressing the elastic member. In the second embodiment described above, the nut moves linearly to the other side in the axial direction, pushing the second annular member and moving it to the other side in the axial direction. Therefore, the movement of the first and second annular members becomes smoother, and the elastic member can be easily compressed.

[0022] In a preferred embodiment, the male screw of the rotating member and the second annular member are capable of contact. In the second embodiment described above, the reaction force is transmitted to the male screw, and the rotating member moves toward one side in the axial direction. By making the male screw and the second annular member capable of contact, the elastic deformation of the elastic member becomes smoother.

[0023] Preferably, the holding portion of the housing has a flat surface extending along the radial direction, and an axial gap is provided between the flat surface and the first annular member. In the above-described first aspect, the nut linearly moves in one axial direction to push the first annular member and move it in one axial direction to compress the elastic member. Therefore, by providing an axial gap between the flat surface and the first annular member, the movement of the first annular member becomes smooth, and the elastic member can be easily compressed.

[0024] Preferably, the elastic member has an annular shape extending along the circumferential direction, and a disk portion extending in the radial direction is provided at one axial end of the holding portion of the housing. The elastic member abuts against the disk portion, whereby the holding portion holds the elastic member. As a result, the elastic member can be held more stably, and the compression of the elastic member becomes smoother.

[0025] Preferably, at least one of the first annular member and the second annular member has a protruding portion that protrudes toward the nut side in the axial direction and can abut against the nut.

[0026] As a result, the movable distance of the nut in the axial direction becomes smaller with respect to the first annular member and the second annular member without the protruding portion. Therefore, the limit range of the steering angle of the steering wheel can be reduced, and the rotatable angle of the steering wheel can be set to be smaller.

[0027] Preferably, the first annular member includes a main body portion and a coating layer provided on the surface layer portion of the main body portion, and the elastic modulus of the coating layer is smaller than the elastic modulus of the main body portion.

[0028] As a result, it becomes possible to reduce the contact noise (interference noise) when the nut hits the first annular member.

Advantages of the Invention

[0029] This disclosure makes it possible to provide a more compact steering device for vehicles. [Brief explanation of the drawing]

[0030] [Figure 1] Figure 1 is a schematic diagram showing the overall configuration of a vehicle steering system according to the first embodiment. [Figure 2] Figure 2 is a cross-sectional view showing a portion of Figure 1. [Figure 3] Figure 3 is a cross-sectional view showing a portion of Figure 2. [Figure 4] Figure 4 is an enlarged cross-sectional view of a portion of Figure 3. [Figure 5] Figure 5 is an enlarged cross-sectional view of a portion of Figure 4. [Figure 6] Figure 6 is an exploded perspective view of the stopper mechanism according to the first embodiment. [Figure 7] Figure 7 is a perspective view of the wave washer shown in Figure 6. [Figure 8] Figure 8 is a cross-sectional view of the stopper mechanism with the nut positioned at one end in the axial direction. [Figure 9] Figure 9 is a cross-sectional view of the stopper mechanism with the nut positioned at the other end in the axial direction. [Figure 10] Figure 10 is a cross-sectional view of the stopper mechanism according to the first modified example. [Figure 11] Figure 11 is a cross-sectional view of the stopper mechanism according to the second modified example. [Figure 12] Figure 12 is a cross-sectional view of the stopper mechanism according to the second embodiment. [Figure 13] Figure 13 is a cross-sectional view of the stopper mechanism according to the third embodiment. [Figure 14] Figure 14 is a cross-sectional view of the stopper mechanism according to the fourth embodiment. [Figure 15] Figure 15 is an enlarged cross-sectional view of the first annular member shown in Figure 14. [Modes for carrying out the invention]

[0031] Embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by those skilled in the art and those that are substantially the same. Furthermore, the components described below can be combined as appropriate. Furthermore, parts with the same structure are given the same reference numerals and their descriptions are omitted. In the coordinate system, the X direction indicates the axial direction of the rotating member, the X1 side is one side in the axial direction, and the X2 side is the other side in the axial direction.

[0032] [First Embodiment] The first embodiment will be described below. Figure 1 is a schematic diagram showing the overall configuration of the vehicle steering device of the first embodiment. Figure 2 is a cross-sectional view showing a part of Figure 1. Figure 3 is a cross-sectional view showing a part of Figure 2.

[0033] As shown in Figure 1, the vehicle steering system 100 comprises a steering unit 4, a control unit (ECU) 14, and a steering unit 20.

[0034] As shown in Figures 1 to 3, the steering unit 4 is equipped with a steering reaction force device 13. When steering the steering wheel 10, the steering reaction force device 13 applies a steering reaction force to the steering wheel 10 in the opposite direction to the steering direction of the steering wheel 10. Based on the operation information, the control unit (ECU) 14 calculates the reaction force torque according to the vehicle's driving state, adjusts the power value supplied to the motor 110 of the steering reaction force device 13 based on the reaction force torque, and the motor 110 operates according to the power value, thereby transmitting the steering reaction force of the steering wheel 10 to the operator. The control unit (ECU) 14 also calculates a current command value based on the operation information and controls the current supplied to the steering motor 21 of the steering unit 20. In the steering unit 20, the steering wheels 22 are steered via various gears connected to the steering motor 21. The configurations of each part of the vehicle steering system 100 will be described in detail below. In the steer-by-wire type vehicle steering system 100, the steering wheel 10 and the steering wheels 22 are mechanically disconnected. However, in the present invention, "disconnected" also includes a configuration in which the steering wheel 10 and the steering wheels 22 can be connected by a clutch device or the like, for example, in an emergency.

[0035] As shown in Figure 1, the steering unit 4 comprises a steering wheel 10, a steering shaft 11, a steering housing 12, and a steering reaction force device 13.

[0036] As shown in Figures 2 and 3, the steering shaft 11 extends in the X direction (axial direction). The steering wheel 10 is rotatably connected to the steering shaft 11. The steering shaft 11 is housed inside the steering housing 12. The steering shaft 11 includes a column shaft 15, an output shaft 16, and a torsion bar 17.

[0037] The column shaft 15 and the output shaft 16 are connected via a torsion bar 17. Specifically, an insertion hole is provided axially at the X1 end of the column shaft 15, and the torsion bar 17 is inserted into this insertion hole. The column shaft 15 and the torsion bar 17 are connected via a pin 122 so that they cannot rotate relative to each other. The output shaft 16 is provided with a through hole that penetrates axially, and the X1 end of the torsion bar 17 is fitted into this through hole. As a result, the output shaft 16 and the torsion bar 17 are connected so that they cannot rotate relative to each other. Therefore, when the steering wheel 10 is rotated, the steering shaft 11 rotates in conjunction with it.

[0038] Furthermore, the steering housing 12 includes a shaft holding member 121, rotation support members 123 and 124, and a sub-housing 127.

[0039] A rotational support member 123 is located on the X1 side of the shaft holding member 121, and a rotational support member 124 is located on the X1 side of the rotational support member 123. A sub-housing 127 is located on the X1 side of the rotational support member 124. A bearing 125 is provided on the radially inner side of the rotational support member 124, and a bearing 126 is provided on the radially inner side of the sub-housing 127. The output shaft 16 is rotatably supported via the bearings 125 and 126. A torque sensor 128 is provided between the rotational support member 123 and the rotational support member 124. The torque sensor 128 detects the rotational torque transmitted between the column shaft 15 and the output shaft 16.

[0040] Here, the steering reaction device 13 includes a steering shaft 11, a worm wheel 18, a worm shaft 19, and a motor 110.

[0041] A worm wheel 18 is mounted on the outer circumference of the output shaft 16 of the steering shaft 11. The worm wheel 18 has a core metal portion 18a and a wheel tooth portion 18b. The wheel tooth portion 18b is provided on the outer circumference of the core metal portion 18a. A worm shaft 19 and a motor 110 are located on the Y2 side (see Figure 6) of the worm wheel 18. The worm shaft 19 is mounted on the output shaft of the motor 110. The worm shaft 19 has a shaft tooth portion 19a. The shaft tooth portion 19a meshes with the wheel tooth portion 18b.

[0042] The motor 110 is the source of the steering reaction force. That is, the output of the motor 110 becomes a reaction torque, and this reaction torque is transmitted from the steering shaft 11 to the steering wheel 10 via the worm wheel 18 and worm shaft 19.

[0043] As shown in Figures 2 and 3, a stopper mechanism 3 is provided on the X1 side of the steering shaft 11 relative to the output shaft 16. The stopper mechanism 3 will be described in detail below. Figure 4 is an enlarged cross-sectional view of a part of Figure 3. Figure 5 is an enlarged cross-sectional view of a part of Figure 4. Figure 6 is an exploded perspective view of the stopper mechanism according to the first embodiment. Figure 7 is a perspective view of the wave washer in Figure 6.

[0044] As shown in Figures 2 and 3, the rotating member 31 has a central axis AX, and the axial direction of the central axis AX coincides with the X direction. The rotating member 31, which is included in the stopper mechanism 3, is spline-fitted to the X1-side end of the output shaft 16 of the steering shaft 11. Specifically, a female spline 319 extending in the X direction is provided on the inner circumference of the rotating member 31, and a male spline extending in the X direction is provided on the outer circumference of the X1-side end of the output shaft 16. The male spline of the output shaft 16 is fitted into the female spline 319 of the rotating member 31. As a result, the rotating member 31 is movable in the X direction relative to the output shaft 16, but cannot rotate in the circumferential direction around the axis of the central axis AX. In other words, the rotating member 31 rotates together with the output shaft 16.

[0045] As shown in Figure 4, the stopper mechanism 3 comprises a rotating member 31, a nut 32, a first annular member 331, an elastic member 34, and a housing 35.

[0046] The rotating member 31 has a central axis AX. The axial direction of the central axis AX is the X direction. The direction around the central axis AX is the circumferential direction. The direction perpendicular to the central axis AX is the radial direction. The rotating member 31 comprises a male screw portion 311, a first cylindrical surface portion 312, and a second cylindrical surface portion 312A.

[0047] The male threaded portion 311 has male threads 314 on its outer circumference. Of the male threads 314, male thread 315 is located at the end furthest towards X1, and male thread 316 is located at the end furthest towards X2. The first cylindrical surface portion 312 is adjacent to the male threaded portion 311 on the X1 side. The first cylindrical surface portion 312 has a cylindrical surface 313. The cylindrical surface 313 extends along the circumferential direction about the axis of the central axis AX. The diameter of the cylindrical surface 313 is smaller than the outer diameter of the male threaded portion 311. That is, the top of the threads of the male thread 314 is located radially outward from the cylindrical surface 313. In other words, the radial position of the bottom portion 315a is approximately the same as the radial position of the cylindrical surface 313, and the male thread 315 protrudes radially outward from the bottom portion 315a.

[0048] Furthermore, the second cylindrical surface portion 312A is adjacent to the male thread portion 311 on the X2 side. The second cylindrical surface portion 312A has a cylindrical surface 313. The radial position of the bottom portion 316a is substantially the same as the radial position of the cylindrical surface 313, and the male thread 316 protrudes radially outward from the bottom portion 316a. The X1 side end of the rotating member 31 has an axial end surface 317, and the X2 side end of the rotating member 31 has an axial end surface 318.

[0049] The nut 32 is provided on the outer circumference of the rotating member 31. The nut 32 has an internal thread 321 on its inner circumference. The internal thread 321 engages with the external thread 314 of the rotating member 31. The outer surface 324 of the nut 32 is a cylindrical surface extending in the circumferential direction. The end of the nut 32 on the X1 side has an axial end face 322, and the end of the nut 32 on the X2 side has an axial end face 323.

[0050] The first annular member 331 has an annular shape that extends in the circumferential direction. The first annular member 331 is inserted into the first cylindrical surface portion 312. The inner diameter of the first annular member 331 is larger than the outer diameter of the first cylindrical surface portion 312. Therefore, the first annular member 331 is movable in the X direction while inserted into the first cylindrical surface portion 312. The first annular member 331 has a vertical wall portion 332 and a cylindrical portion 333. The vertical wall portion 332 extends in the radial direction. The cylindrical portion 333 extends in the circumferential direction. The vertical wall portion 332 and the cylindrical portion 333 are connected via a corner portion 334. An axial end face 335 is provided at the X1 side end of the cylindrical portion 333.

[0051] An example of an elastic member 34, the wave washer 341, is positioned adjacent to the first annular member 331 on the X1 side. Note that the elastic member 34 is not limited to the wave washer 341, and various elastic members such as disc springs can be applied. When viewed from the X direction, the wave washer 341 overlaps with the axial end face 335. The wave washer 341 is in contact with the axial end face 335 and is elastically deformable in the X direction in contact with the first annular member 331. Note that the wave washer 341 and the axial end face 317 of the rotating member 31 are separated in the X direction. That is, the wave washer 341 and the axial end face 317 of the rotating member 31 do not come into contact.

[0052] As shown in Figures 4 and 7, the wave washer 341 has an inner peripheral edge 345 on the radially inward side and an outer peripheral edge 344 on the radially outward side. In addition, bent portions 342 and bent portions 343 are arranged alternately along the circumferential direction. The bent portion 342 is convex toward the X2 side, and the bent portion 343 is convex toward the X1 side. The bent portion 342 abuts against the axial end face 335, and the bent portion 342 abuts against the disc portion 352g, which will be described later.

[0053] As shown in Figure 4, the housing 35 is positioned on the outer circumference of the rotating member 31, nut 32, first annular member 331, and wave washer 341. The housing 35 comprises a first housing 351 and a second housing 352.

[0054] As shown in Figures 4 and 6, the first housing 351 is positioned on the X2 side of the housing 35. The first housing 351 has a coupling portion 351a, a vertical wall portion 351b, a cylindrical portion 351c, and a flange 351d (see Figure 6).

[0055] The connecting portion 351a fits into the connected portion 352a of the second housing 352 and is connected to the connected portion 352a. The vertical wall portion 351b extends radially, and the cylindrical portion 351c extends circumferentially. As shown in Figure 6, the first housing 351 has flanges 351d that protrude to the Y1 side and the Y2 side. A second bolt hole H2 is provided in the flange 351d. A female thread is provided on the inner circumference of the second bolt hole H2, and this female thread engages with the male thread of the bolt BL.

[0056] As shown in Figures 4 and 6, the second housing 352 has a cylindrical portion 352b, a projection 352d, a disc portion 352g, a flange 352h, and a protruding portion 352i.

[0057] The cylindrical portion 352b extends in the circumferential direction. The disc portion 352g extends radially and seals the opening on the X1 side of the cylindrical portion 352b. The cylindrical portion 352b and the disc portion 352g are connected via a projection 352d. The projection 352d protrudes toward the inside of the second housing 352. Specifically, the projection 352d protrudes radially inward and toward the X2 side. The projection 352d has a flat surface 352e and a cylindrical surface 352f. The flat surface 352e is the axial end face on the X2 side of the projection 352d, and the cylindrical surface 352f is the inner circumferential surface of the projection 352d.

[0058] Here, as shown in Figure 5, there is a gap G in the X direction between the flat surface 352e and the vertical wall portion 332 of the first annular member 331. The size of this gap G is, for example, the distance over which the wave washer 341 can be deformed in the axial direction. Also, as shown in Figure 4, a holding portion 352c is formed by the disc portion 352g and the projection portion 352d. That is, the holding portion 352c for holding the wave washer 341 is formed on the X2 side of the disc portion 352g and the inner circumference side of the projection portion 352d.

[0059] Furthermore, as shown in Figure 6, the second housing 352 has flanges 352h that protrude to the Y1 and Y2 sides. A first bolt hole H1 is provided in the flange 352h. A through hole is provided on the inner circumference of the first bolt hole H1, and the shaft portion of the bolt BL passes through this through hole. A projection 325 is provided on the outer circumferential surface 324 of the nut 32, which protrudes radially outward. The projection 325 extends in the X direction. The second housing 352 also has a projection 352i that protrudes radially outward. A groove 352j is provided on the inner circumference of the projection 352i. The projection 325 is fitted into the groove 352j. In this way, these projections 352i and 325 prevent the nut 32 from rotating relative to the housing 35.

[0060] As shown in Figure 4, a second annular member 331A is inserted into the second cylindrical surface portion 312A. The second annular member 331A is an example of a nut contact portion 350. The second annular member 331A has a vertical wall portion 332A and a cylindrical portion 333A. The vertical wall portion 332A extends radially. The vertical wall portion 332A is positioned opposite the nut 32 on the X2 side. The cylindrical portion 333A extends circumferentially. The vertical wall portion 332A and the cylindrical portion 333A are connected via a corner portion 334A. In addition, the second annular member 331A is in constant contact with the male screw 316 of the rotating member 31. Specifically, the bottom portion 316a of the male screw 316 and the corner portion 334A of the second annular member 331A are in contact. In other words, the second annular member 331A is sandwiched in the X direction between the first housing 351 and the male screw 316. The second annular member 331A can contact the axial end face 323 of the nut 32 when the nut 32 moves toward the X2 side. Here, the second annular member 331A and the rotating member 31 can move relative to each other in the axial direction (X direction). Therefore, when the nut 32 moves toward the X2 side and the axial end face 323 compresses the vertical wall portion 332A of the second annular member 331A in the X direction, a reaction force is generated that causes the vertical wall portion 332A to return to its original position, and this reaction force is transmitted to the rotating member 31. As a result, the second annular member 331A pushes the rotating member 31 toward the X1 side.

[0061] Next, with reference to Figure 6, the assembly procedure for the stopper mechanism 3 will be briefly explained. As shown in Figure 6, first, the rotating member 31 is fastened to the inner circumference of the nut 32, the first annular member 331 is inserted into the first cylindrical surface portion 312 of the rotating member 31, and the second annular member 331A is inserted into the second cylindrical surface portion 312A. Next, in this state, the rotating member 31, nut 32, first annular member 331, and second annular member 331A are inserted into the inside of the second housing 352. At this time, the projection 325 is fitted into the groove portion 352j. Then, the first housing 351 is bolted to the second housing 352. Specifically, the flange 351d is abutted against the flange 352h, and the second bolt hole H2 and the first bolt hole H1 are connected. Then, the bolt BL is passed through the first bolt hole H1 and engaged with the female thread of the second bolt hole H2, thereby completing the assembly of the stopper mechanism 3.

[0062] Next, the behavior of the stopper mechanism 3 will be briefly explained. Figure 8 is a cross-sectional view of the stopper mechanism when the nut is located at one end in the axial direction. Figure 9 is a cross-sectional view of the stopper mechanism when the nut is located at the other end in the axial direction.

[0063] (First aspect) The nut 32 is non-rotatably supported by the housing 35. Therefore, as shown in Figure 8, when the rotating member 31 rotates, the nut 32 moves (linearly) toward the X1 side relative to the rotating member 31, as indicated by arrow D1. The axial end face 322 of the nut 32 comes into contact with the vertical wall portion 332 of the first annular member 331. As explained with reference to Figure 5, there is a gap G in the X direction between the flat surface 352e and the vertical wall portion 332 of the first annular member 331. Therefore, the first annular member 331 moves toward the X1 side, as indicated by arrow D2, and the axial end face 335 compresses the wave washer 341 in the X direction, causing the wave washer 341 to elastically deform.

[0064] (Second aspect) As shown in Figure 9, when the rotating member 31 rotates in the opposite direction to that of the first embodiment, the nut 32 moves (linearly) toward the X2 side relative to the rotating member 31 as shown by arrow D11. Therefore, the axial end face 323 of the nut 32 comes into contact with the vertical wall portion 332A of the second annular member 331A. Since the second annular member 331A is supported by the first housing 351 in the X direction, a reaction force is generated from the second annular member 331A toward the X1 side. This reaction force is transmitted to the male screw 316, and the rotating member 31 moves toward the X1 side as shown by arrow D12. Since the rotating member 31 is provided with a male screw 315, the male screw 315 also moves toward the X1 side as shown by arrow D13. The bottom portion 315a of the male screw 315 strikes the corner portion 334 of the first annular member 331. Here, as explained with reference to Figure 5, there is a gap G in the X direction between the flat surface 352e and the vertical wall portion 332. Consequently, the first annular member 331 moves towards the X1 side as shown by arrow D14. Then, the axial end face 335 compresses the wave washer 341 in the X direction, causing the wave washer 341 to elastically deform.

[0065] As described above, the steering device for a vehicle according to the first embodiment includes a rotating member 31 having a male screw portion 311 and a first cylindrical surface portion 312, a nut 32 that moves in the X direction relative to the rotating member 31 when not rotating, a first annular member 331 inserted into the first cylindrical surface portion 312 and movable in the X direction, a wave washer 341 (elastic member 34) that abuts against the first annular member 331 and is elastically deformable in the X direction, and a housing 35. The housing 35 has a holding portion 352c that holds the elastic member 34, and a second annular member 331A (nut contact portion 350) that can abut against the nut 32 when the nut 32 moves and transmits the reaction force toward the X1 side generated when the nut 32 abuts to the rotating member 31.

[0066] Thus, in this embodiment, only one wave washer 341, which is an elastic member 34, is provided. That is, a wave washer 341 is provided on the X1 side relative to the nut 32, and no wave washer 341 is provided on the X2 side relative to the nut 32. As a result, there are fewer elastic members 34 than in Patent Document 1, the axial distance of the stopper mechanism 3 is shortened, and consequently the vehicle steering device 100 can be made smaller. The following briefly explains how the stopper mechanism 3 functions effectively even with only one wave washer 341.

[0067] First, in the first embodiment, when the nut 32 moves linearly toward the X1 side, as shown in Figure 8, the axial end face 322 of the nut 32 compresses the wave washer 341 in the X direction via the first annular member 331, causing the wave washer 341 to elastically deform.

[0068] Next, in the second embodiment, when the nut 32 moves linearly toward the X2 side, as shown in Figure 9, the axial end face 323 of the nut 32 comes into contact with the second annular member 331A (nut contact portion 350). Since the second annular member 331A is supported by the first housing 351 in the X direction, a reaction force is generated from the second annular member 331A toward the X1 side. This reaction force is transmitted to the male screw 316, and the rotating member 31 moves toward the X1 side. Subsequently, the axial end face 335 of the first annular member 331 compresses the wave washer 341 in the X direction, causing the wave washer 341 to elastically deform and absorb the impact.

[0069] Thus, in both the first mode in which the nut 32 moves directly toward X1 and the second mode in which the nut 32 moves directly toward X2, one wave washer 341 is elastically deformed. Therefore, as described above, in this embodiment, since the number of wave washers 341 is smaller than in Patent Document 1, the axial distance of the stopper mechanism 3 is shortened, and consequently the vehicle steering device 100 can be made smaller.

[0070] The rotating member 31 has a second cylindrical surface portion 312A. The nut contact portion 350 is a second annular member 331A that is inserted into the second cylindrical surface portion 312A.

[0071] As described above, in the second embodiment, when the nut 32 moves in a straight line toward X2, as shown in Figure 9, the nut 32 comes into contact with the second annular member 331A, and a reaction force is generated from the second annular member 331A toward X1. This reaction force is transmitted to the male screw 316, and the rotating member 31 moves toward X1. In this way, the second annular member 331A functions properly as the nut contact portion 350. Furthermore, if the second annular member 331A is damaged, its function as the nut contact portion 350 can be easily restored by replacing it with a new one. In addition, the replaceable parts are not limited to the second annular member 331A; for example, the wave washer 341 can also be replaced.

[0072] [First variation] The first modified example is described below. Figure 10 is a cross-sectional view of the stopper mechanism according to the first modified example.

[0073] In the first embodiment, the second annular member 331A was used as the nut contact portion 350, but in the first modified example, the first housing 351A is used as the nut contact portion 350. A brief explanation follows below.

[0074] In the stopper mechanism 3A according to the first modified example, the second annular member 331A of the first embodiment is not provided. That is, the first housing 351A is used as the nut contact portion 350. The first housing 351A as the nut contact portion 350 is located on the X2 side of the housing 35. The first housing 351A has a connecting portion 351a, a vertical wall portion 351Ab, and a cylindrical portion 351Ac.

[0075] The connecting portion 351a fits into the connected portion 352a of the second housing 352 and is coupled to the connected portion 352a. The vertical wall portion 351Ab extends radially, and the cylindrical portion 351Ac extends circumferentially. The cylindrical portion 351Ac abuts against the male screw 316. The connecting portion 351a, the vertical wall portion 351Ab, and the cylindrical portion 351Ac are integrally molded.

[0076] The behavior of the first modified example is described below. The behavior of the first embodiment is the same as that described in the first embodiment. The behavior of the second example is described below. First, the axial end face 323 of the nut 32 comes into contact with the vertical wall portion 351Ab of the first housing 351A. This generates a reaction force from the vertical wall portion 351Ab toward the X1 side. This reaction force is transmitted to the male screw 316, and the rotating member 31 moves toward the X1 side. Since the male screw 315 also moves toward the X1 side, the first annular member 331 moves toward the X1 side. Then, the axial end face 335 compresses the wave washer 341 in the X direction, causing the wave washer 341 to elastically deform.

[0077] As described above, the steering device for a vehicle according to the first modified example includes a first housing 351A as an example of the nut contact portion 350. The first housing 351A is capable of contacting the nut 32 when the nut 32 moves, and transmits the reaction force toward the X1 side that is generated when the nut 32 contacts to the rotating member 31.

[0078] As described above, when the nut 32 moves in a straight line toward X2, the nut 32 comes into contact with the first housing 351A, and a reaction force is generated from the first housing 351A toward X1. In this way, even when the first housing 351A is used as the nut contact portion 350, the stopper mechanism 3A functions properly.

[0079] [Second variation] A second modified example is described below. Figure 11 is a cross-sectional view of the stopper mechanism according to the second modified example.

[0080] In the stopper mechanism 3B according to the second modified example, a sealing member S is provided. This will be briefly explained below. As shown in Figure 11, the second housing 352B has a projection 352Bd at the end on the X1 side. A recess 354 is provided on the inner circumference side of the projection 352Bd. The recess 354 extends in an annular shape along the circumferential direction. Also, in the cross-section shown in Figure 11, the recess 354 has a substantially trapezoidal shape in which the distance in the X direction decreases as it moves radially outward. An annular sealing member S is housed inside the recess 354. A through hole 353 is provided in the disc portion 352Cg of the second housing 352B. The through hole 353 has a circular shape that extends in the circumferential direction around the axis of the central axis AX.

[0081] Furthermore, the first annular member 331B has a vertical wall portion 332 and a cylindrical portion 333B. The cylindrical portion 333B of the first annular member 331B differs from that of the first annular member 331. Specifically, the distance in the X direction of the cylindrical portion 333B relating to the first annular member 331B is greater than the distance in the X direction of the cylindrical portion 333 relating to the first annular member 331. The cylindrical portion 333B seals the opening on the inner circumference side of the recess 354. The inner circumference tip S10 of the sealing member S abuts against the cylindrical portion 333B.

[0082] As described above, in the second modified vehicle steering device, the second housing 352B has a projection 352Bd with a recess 354, and an annular sealing member S is housed in the recess 354. The inner circumferential tip S10 of the sealing member S abuts against the cylindrical portion 333B. A through hole 353 is provided in the disc portion 352Cg of the second housing 352B.

[0083] There is a possibility that foreign matter such as dust may enter the inside of the second housing 352B through the through hole 353. However, since the tip S10 of the sealing member S abuts against the first annular member 331B, it is possible to suppress the entry of such foreign matter. In addition, the sealing member S can prevent the oil inside the second housing 352B from leaking out to the outside.

[0084] [Second Embodiment] A second embodiment will be described below. Figure 12 is a cross-sectional view of the stopper mechanism according to the second embodiment.

[0085] In the stopper mechanism 3C according to the second embodiment, a through hole 353 is provided in the disc portion 352Cg of the second housing 352C. The through hole 353 has a circular shape that extends in the circumferential direction around the axis of the central axis AX. The through hole 353 has an inner diameter DI1.

[0086] Furthermore, an annular wave washer 341 is positioned on the X2 side of the disc portion 352Cg, and the wave washer 341 has an inner diameter DI2. In addition, as described above, a female spline 319 is provided on the inner circumference of the rotating member 31. The rotating member 31 has an inner diameter DI3. The inner diameter DI2 of the wave washer 341 is greater than or equal to the inner diameter DI3 of the rotating member 31, and the inner diameter DI1 of the through hole 353 is greater than or equal to the inner diameter DI2 of the wave washer 341.

[0087] As described above, in the steering device for a vehicle according to the second embodiment, an annular through hole 353 is provided in the holding portion 352c of the second housing 352C. The inner diameter DI2 is greater than or equal to the inner diameter DI3, and the inner diameter DI1 is greater than or equal to the inner diameter DI2.

[0088] Therefore, by passing through the through hole 353 and the inner circumference of the wave washer 341, a component such as a shaft extending in the axial direction can be fitted into the female spline 319 on the inner circumference of the rotating member 31.

[0089] [Third Embodiment] A third embodiment will be described below. Figure 13 is a cross-sectional view of the stopper mechanism according to the third embodiment.

[0090] In the stopper mechanism 3D according to the third embodiment, the first annular member 331C and the second annular member 331D differ from those of the stopper mechanism 3 according to the first embodiment.

[0091] The first annular member 331 according to the first embodiment has a vertical wall portion 332 and a cylindrical portion 333. In contrast, the first annular member 331C according to the third embodiment further has a projection portion 336. That is, the first annular member 331C has a vertical wall portion 332, a cylindrical portion 333, and a projection portion 336. The projection portion 336 extends in the circumferential direction. The projection portion 336 extends from the radially outer end of the vertical wall portion 332 toward the X2 side.

[0092] The second annular member 331D has a vertical wall portion 332A, a cylindrical portion 333A, and a projection portion 337. The projection portion 337 extends in the circumferential direction. The projection portion 337 extends from the radially outer end of the vertical wall portion 332A toward X1.

[0093] Thus, the first annular member 331C has a projection 336 that protrudes toward the nut side in the X direction (axial direction) and is capable of contacting the nut 32. The second annular member 331D has a projection 337 that protrudes toward the nut side in the X direction (axial direction) and is capable of contacting the nut 32.

[0094] As described above, in the steering device for a vehicle according to the third embodiment, each of the first annular member 331C and the second annular member 331D has a projection 336 or projection 337 that protrudes toward the nut side in the X direction and can abut against the nut 32.

[0095] Therefore, in the third embodiment, the distance that the nut 32 can move in the X direction is smaller than that of the first annular member 331 and the second annular member 331A, which do not have the protrusion 336 or protrusion 337 according to the first embodiment. This reduces the limit range of the steering angle of the steering wheel, and allows the rotatable angle of the steering wheel 10 to be set to a smaller value.

[0096] [Fourth Embodiment] A fourth embodiment will be described below. Figure 14 is a cross-sectional view of the stopper mechanism according to the fourth embodiment. Figure 15 is an enlarged cross-sectional view of the first annular member shown in Figure 14.

[0097] In the stopper mechanism 3E according to the fourth embodiment, the first annular member 331E differs from that of the stopper mechanism 3 according to the first embodiment.

[0098] As shown in Figures 14 and 15, the first annular member 331E has a vertical wall portion 332 and a cylindrical portion 333. Each of these vertical wall portion 332 and cylindrical portion 333 has a main body portion 338 and a covering layer 339.

[0099] The coating layer 339 is provided on the surface of the main body 338. The main body 338 is, for example, made of metal, and the coating layer 339 is, for example, made of resin. The elastic modulus of the main body 338 is, for example, 205 GPa. The elastic modulus of the coating layer 339 is, for example, 650 MPa. Thus, the elastic modulus of the coating layer 339 is smaller than that of the main body 338.

[0100] As described above, in the steering device for a vehicle according to the fourth embodiment, the first annular member 331E comprises a main body portion 338 and a covering layer 339 provided on the surface portion of the main body portion 338. The elastic modulus of the covering layer 339 is smaller than that of the main body portion 338.

[0101] This makes it possible to reduce the contact noise (interference noise) when the nut 32 comes into contact with the first annular member 331E. In addition, the coating layer 339 reduces friction between the cylindrical portion 333 of the first annular member 331E and the second cylindrical surface portion 312A of the rotating member 31. As a result, when the nut 32 comes into contact with the first annular member 331E, the first annular member 331E is prevented from getting caught on the second cylindrical surface portion 312A. Furthermore, by applying grease to the coating layer 339, the aforementioned reduction in contact noise (interference noise) and the prevention of the first annular member 331E from getting caught can be further suppressed. [Explanation of Symbols]

[0102] 3. Stopper mechanism 3A Stopper mechanism 3B Stopper mechanism 3C Stopper mechanism 3D Stopper Mechanism 3E Stopper mechanism 4. Steering Unit 10 Steering Wheel 11 Steering shaft 12 Steering Housing 13. Steering reaction device 14 Control Unit (ECU) 15 Column axis 16 Output shaft 17 Torsion bar 18 Worm Wheel 18a Core metal part 18b Wheel teeth 19 Worm shaft 19a Shaft teeth 20 Snake Unit 21 Steering motor 22 steering wheels 31 Rotating member 32 nuts 34 Elastic members 35 Housing 100 Vehicle steering systems 110 Motor 121 Shaft holding member 122 pins 123 Rotating support member 124 Rotating support member 125 bearings 126 Bearing 127 Subhousing 128 Torque Sensor 311 Male threaded section 312 First cylindrical surface part 312A 2nd cylindrical surface part 313 Cylindrical surface 314 Male screw 315 Male screw 315a bottom 316 Male screw 316a bottom 317 Axial end face 318 Axial end face 319 Female spline 321 Female thread 322 Axial end face 323 Axial end face 324 Outer surface 325 Protrusion 331 First annular member 331A Second annular member (nut contact portion) 331B First annular member 331C First annular member 331D Second annular member 331E First annular member 332 Vertical wall section 332A Vertical wall section 333 Cylinder part 333A Cylinder 334 corners 334A Corner 335 Axial end face 336 Protrusion 337 Protrusion 338 Main body 339 Covering layer 341 Wave Washer 342 Folding section 343 Folding section 344 Outer edge 345 Inner periphery 350 Nut contact area 351 Housing No. 1 351a Joint 351b Vertical wall section 351A First housing (nut contact area) 351Ab Vertical wall section 351c Cylindrical part 351d flange 352 Second Housing 352a Connected part 352b Cylindrical section 352c holding part 352d protrusion 352e flat surface 352f Cylindrical surface 352g disc portion 352h flange 352i protrusion 352j Groove 352B Second Housing 352Bd Protrusion 352C Second Housing 352Cg disc section 353 Through hole 354 recess BL Bolt G Gap H1 First bolt hole H2 Second bolt hole S sealing member S10 Tip

Claims

1. A vehicle steering system in which the steering wheels and the steering wheel are not mechanically connected, The steering wheel is equipped with a stopper mechanism that restricts the range of rotation angle of the steering wheel when it is rotated, The stopper mechanism is, A rotating member having a male threaded portion on its outer circumference, a first cylindrical surface portion adjacent to the male threaded portion on one side in the axial direction of the central axis, extending along the circumferential direction around the central axis, and having a cylindrical surface with a diameter smaller than the outer diameter of the male threaded portion, and which rotates circumferentially in accordance with the rotation of the steering wheel, A nut disposed on the outer circumference of the rotating member, having an inner circumference with a female thread that engages with the male thread, and moving axially relative to the rotating member when not rotating due to the rotation of the rotating member, A first annular member is inserted into the first cylindrical surface of the rotating member and is movable in the axial direction while in contact with the nut or the male thread portion, An elastic member is disposed adjacent to the first annular member on one side in the axial direction and is in contact with the first annular member and is elastically deformable in the axial direction, The rotating member, the nut, the first annular member, and the housing disposed on the outer circumference of the elastic member, Equipped with, The aforementioned housing is A holding portion for holding the elastic member, A nut contact portion is positioned opposite the nut on the other side in the axial direction, is capable of contacting the nut when the nut moves, and transmits the reaction force generated when the nut contacts the nut toward one side in the axial direction to the rotating member. Steering device for vehicles.

2. The aforementioned rotating member is It has a second cylindrical surface portion adjacent to the male thread portion on the other side in the axial direction, extending along the circumferential direction, and having a cylindrical surface with a diameter smaller than the outer diameter of the male thread portion, The nut contact portion is, The second annular member is inserted into the second cylindrical surface portion. The steering device for a vehicle according to claim 1.

3. The elastic member has an annular shape extending along the circumferential direction, The rotating member has a cylindrical shape that extends along the circumferential direction, The retaining portion of the housing is provided with an annular through hole that penetrates axially and extends along the circumferential direction. The inner diameter of the elastic member is greater than or equal to the inner diameter of the rotating member. The inner diameter of the through hole in the holding portion is greater than or equal to the inner diameter of the elastic member. The steering device for a vehicle according to claim 1 or 2.

4. The first annular member and the first cylindrical surface portion are capable of relative movement in the axial direction. The second annular member and the second cylindrical surface portion are capable of relative movement in the axial direction. The steering device for a vehicle according to claim 2.

5. The male screw of the rotating member and the second annular member are capable of contacting each other. The steering device for a vehicle according to claim 2.

6. The retaining portion of the housing has a flat surface extending radially, An axial gap is provided between the flat surface and the first annular member. The steering device for a vehicle according to claim 1.

7. The elastic member has an annular shape extending along the circumferential direction, A disc portion extending in the radial direction is provided at one end in the axial direction of the holding portion of the housing. The elastic member comes into contact with the disc portion, thereby the holding portion holds the elastic member. The steering device for a vehicle according to claim 1 or 2.

8. At least one of the first annular member and the second annular member has a projection that protrudes toward the nut in the axial direction and is capable of contacting the nut. The steering device for a vehicle according to claim 2.

9. The first annular member comprises a main body and a coating layer provided on the surface of the main body, wherein the elastic modulus of the coating layer is smaller than the elastic modulus of the main body. The steering device for a vehicle according to claim 1 or 2.

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