JP2008049798A - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device capable of damping collision of a shaft coupling and a housing or an end member without causing reduction of rigidity of an end of a rack shaft. <P>SOLUTION: In the steering device, the rack shaft 11 is penetrated into an approximately cylindrical housing consisting of a rack housing 3 and a cylinder tube 8, and ball joints 13 is threadingly-attached to both ends. Further, to both ends of the rack shaft, an approximately annular shock absorbing member 15 for damping the collision of an inner end surface of the ball joint and an outer end surface of the rack housing or an outer end surface of an end cap arranged on an outer end of the cylinder tube in the maximum slide of the rack shaft is fitted. As such, a locking groove 16 is formed on the outer circumsferencial surface at the end of the rack shaft and the shock-absorving member is fixedly locked to the outer circumsference at the end of the rack shaft through the locking groove, so that the end face of the rack shaft can be formed into a flat annular form continuously, which prevents rigidity reduction at the end of the rack shaft. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a steering apparatus that is applied to, for example, a rack and pinion type power steering apparatus of a vehicle and has a buffer member that buffers a collision between a shaft coupling that holds a tie rod and a housing or an end member at an end of a rack shaft.

  For example, as a rack and pinion type steering device for a vehicle, for example, a device as shown in Patent Document 1 below is known.

  In this power steering device, a hollow cylindrical rack shaft that meshes with a pinion shaft is disposed in a cylinder tube so as to be movable in the axial direction, and a tie rod that is linked to a wheel is rotatable at the end of the rack shaft. A ball joint to be held is screwed, and an end cap that restricts the maximum movement position of the rack shaft in the axial direction by abutting the ball joint is screwed to the end of the cylinder tube. A buffer member for buffering the collision between the ball joint and the end cap when the amount of movement of the rack shaft reaches a maximum is fitted to the end of the rack shaft.

  The buffer member is formed in a substantially annular shape from a synthetic resin, and a pair of engaging protrusions facing each other in the radial direction are provided on one end face along the axial direction. The buffer member is locked and fixed to the end portion of the rack shaft by fitting both the engaging protrusions into a locking groove formed in the end surface of the rack shaft along the radial direction. .

Thus, in the steering device, the buffer member collides with the end cap immediately before the ball joint and the end cap collide, and is pressed between the ball joint and the end cap at the maximum movement position of the rack shaft. Then, by elastically deforming in the radial direction, the impact of the both is reduced, and the generation of abnormal noise associated with the impact is prevented.
JP 2005-161942 A

  However, in the conventional steering device, since the locking groove is notched in the radial direction on the end surface of the rack shaft, the rigidity of the end portion of the rack shaft is lowered. For this reason, for example, when a load input to the wheel from the road surface acts on the rack shaft obliquely in the axial direction via the tie rod, the peripheral wall at the end of the rack shaft is plastically deformed radially outward with the locking groove as the center. The so-called opening of mouth is concerned.

  Therefore, there is a possibility that the coupling force of the coupling portion between the rack shaft and the ball joint may not be sufficiently obtained. Conventionally, the thickness and outer diameter of the rack shaft have been inevitably increased in order to eliminate this concern. As a result, there is a problem that the steering device is increased in size and weight.

  The present invention has been devised by paying attention to such a technical problem, and without causing a reduction in rigidity of the end portion of the rack shaft, the shaft coupling that holds the tie rod and the housing or the end member. A steering apparatus capable of buffering a collision is provided.

  According to the first aspect of the present invention, a rack shaft disposed in the housing so as to be movable in the axial direction, a shaft joint coupled to both ends of the rack shaft, and a pivot joint supported by the shaft joint. A tie rod linked to the wheel, an end member provided at one end of the housing in the axial direction and slidably supporting the rack shaft, and disposed at both ends of the rack shaft. A buffer member for buffering the collision of the shaft joint by contacting the outer end surface of the other end in the axial direction of the housing or the outer end surface of the end member during movement, and outer peripheral surfaces of both ends of the rack shaft An engaging means for engaging and holding the buffer member is provided between the buffer member and the both end surfaces in the axial direction of the rack shaft are continuously formed in a flat annular shape.

  According to this invention, the both end surfaces in the axial direction of the rack shaft are continuously formed in a flat annular shape by engaging and fixing the buffer member to the outer peripheral surfaces of the both ends of the rack shaft via the engaging means. Can be formed. Therefore, sufficient rigidity is secured at both ends of the rack shaft, and so-called opening at each end of the rack shaft is prevented even if a load from an oblique direction acts on each end of the rack shaft. Can be prevented.

  According to a second aspect of the present invention, a rack shaft disposed in the housing so as to be movable in the axial direction, a shaft joint coupled to both ends of the rack shaft, and a pivot joint supported by the shaft joint. Tie rods that are linked to the wheels, end members that are provided at both ends in the axial direction of the housing and slidably support the rack shaft, and are disposed at both ends of the rack shaft, A buffer member for buffering the collision of the shaft coupling by abutting against the outer end surface of the end member during sliding, and the buffer member between the outer peripheral surface of both ends of the rack shaft and the buffer member An engagement means for engaging and holding the rack shaft is provided, and both end surfaces in the axial direction of the rack shaft are continuously formed in a flat annular shape.

  The invention according to claim 3 is characterized in that a part of the engaging means is formed by a locking groove formed on each outer peripheral surface of both ends of the rack shaft.

  Embodiments of a steering apparatus according to the present invention will be described below in detail with reference to the drawings.

  1 to 10 show a first embodiment of a steering apparatus according to the present invention, which is applied to a rack and pinion type power steering apparatus for a vehicle, as in the prior art.

  As shown in FIG. 10, this power steering device has one end connected to a steering wheel (not shown), and a steering shaft 1 that rotates when the steering wheel is steered, and the other end of the steering shaft 1 is accommodated. A gear box 2 that is biased to one end in the width direction of the vehicle body, a rack housing 3 that is provided at the lower end of the gear box 2 and extends in the width direction of the vehicle body, and a shaft of the rack housing 3 A power cylinder 4 coaxially joined to the other end in the direction.

  In the gear box 2, a rod-like torsion bar 5 whose one end is connected to the steering shaft 1, a rotary valve 6 provided so as to surround the torsion bar 5, and one end through the torsion bar 5. A pinion shaft 7 connected to the steering shaft 1 is accommodated. Then, the rotary valve 6 is opened and closed by twisting the torsion bar 5 based on the relative rotation between the steering shaft 1 and the pinion shaft 7, and the hydraulic oil supplied to the power cylinder 4 in accordance with the twist amount. The amount is controlled.

  The rack housing 3 has a substantially cylindrical rack that meshes with the other end of the pinion shaft 7 and the other end of the pinion shaft 7 so as to move forward and backward in the axial direction according to the rotation of the steering wheel. The rack shaft 11 is provided across the rack housing 3 and the power cylinder 4. The rack shaft 11 is linked to left and right wheels via a knuckle (not shown), and both wheels are moved by pulling the knuckle left and right while moving in the axial direction according to the rotation angle of the steering wheel. The orientation is changed.

  The power cylinder 4 is formed in an almost cylindrical shape by an aluminum alloy material, and the rack shaft 11 is accommodated in a penetrating state on the inner peripheral side of a cylinder tube 8 constituting one end side in the axial direction of the housing according to the present invention. The piston 9 provided on the outer peripheral side of the rack shaft 11 is divided into two pressure chambers, a first hydraulic chamber P1 on the right side in FIG. 10 and a second hydraulic chamber P2 on the left side in FIG. In the power cylinder 4, the hydraulic pressure supplied to the pressure chambers P 1 and P 2 via the first oil passage pipe 10 a and the second oil passage pipe 10 b connected to the gear housing 2 is supplied to the rack shaft 11. By assisting the movement in the axial direction, the steering force of the driver is assisted.

  In addition, an end cap 12 that is an end member that slidably supports one end of the rack shaft 11 is provided at one end of the power cylinder 4 (left end in FIG. 10). The end cap 12 is formed in a hollow substantially bolt shape, and is screwed into one end of the cylinder tube 8 from the outside in the axial direction, thereby supporting the rack shaft 11 in a penetrating state along the axial direction. 8 is closed at one end.

  As shown in FIGS. 4 and 5, the rack shaft 11 is formed of an aluminum alloy material in a substantially cylindrical shape, and both end surfaces 11 a and 11 a in the axial direction are continuously formed in a flat annular shape. Further, on the inner peripheral surfaces of both end portions in the axial direction of the rack shaft 11, female thread portions 11b are formed in a predetermined range along the axial direction.

  As shown in FIGS. 1 and 10, a ball joint 13 that is a shaft joint is screwed to both ends of the rack shaft 11 via the female screw portion 11 b, and each ball joint 13 is not shown in the figure. One end of a tie rod 14 that pushes and pulls the knuckle arm to angle the wheel is rotatably connected.

  As shown in FIG. 10, the tie rod 14 has a cylindrical portion 14a formed in a substantially cylindrical shape, a spherical portion 14b formed at one end and connected to the ball joint 13, and formed at the other end. It mainly comprises a tie rod end (not shown) linked to the knuckle.

  As shown in FIGS. 1 and 10, the ball joint 13 is a well-known ball joint, and has a substantially cylindrical holding portion 13 a that holds the spherical portion 14 b of the tie rod 14, and the holding portion 13 a A threaded portion 13c formed with a male screw that is screwed into the female threaded portion 11b is projected in the axial direction from the inner end surface 13b that is the outer bottom surface. The ball joint 13 has its threaded portion 13c screwed to the female threaded portion 11b of the rack shaft 11, and the inner end surface 13b of the holding portion 13a is fixed to the end surface 11a of the rack shaft 11 with screws. Yes.

  As shown in FIG. 10, the holding portion 13 a has a spherical sliding surface on the inner peripheral side, and is accommodated and held so as to surround the spherical portion 14 b of the tie rod 14. Thereby, the tie rod 14 is connected to be able to rotate three-dimensionally with the spherical portion 14b as a fulcrum.

  With such a configuration, when the rack shaft 11 slides in the right direction in FIG. 10, the inner end surface 13 b of the holding portion 13 a of the ball joint 13 contacts the outer end surface 12 a in the axial direction of the end cap 12. As a result, the maximum sliding position of the rack shaft 11 in the right direction in FIG. 10 is restricted, while when sliding in the left direction in FIG. 10, the inner end surface 13b of the holding portion 13a is used as the rack housing. 3, the maximum sliding position of the rack shaft 11 in the left direction in FIG. 10 is regulated.

  Further, as shown in FIGS. 1 to 3 and 10, a pair of buffer members 15 are respectively provided on the outer peripheral surfaces of both end portions in the axial direction of the rack shaft 11 by engaging means.

  The buffer member 15 is formed in a substantially annular shape by urethane resin, and functions as a buffer when the inner end surface 13b of the holding portion 13a of the ball joint 13 contacts the end surface 3a of the rack housing 3 or the outer end surface 12a of the end cap 12. Is demonstrating. The engaging means includes a pair of locking grooves 16 formed in the outer circumferential surface of both end portions in the axial direction in a circular groove shape along the circumferential direction, and a radial direction on the inner circumferential surface of the buffer member 15. And an engaging protrusion 17 corresponding to the locking groove 16.

  As shown in FIGS. 1 and 3, the locking groove 16 is formed in a substantially arc shape in the longitudinal section, and its axial position is within the range of the axial region into which the threaded portion 13 c of the ball joint 13 is screwed. It is formed at an arbitrary position.

  As shown in FIG. 3, the engaging protrusion 17 protrudes from the inner peripheral edge that is the inner side in the axial direction when assembled to the rack shaft 11, and its protrusion amount (outer diameter) R is locked. The groove 16 is formed slightly smaller than the groove depth (inner diameter) r.

  In other words, the buffer member 15 is engaged with the locking groove 16 through a slight gap c1 which is the difference between the groove depth r of the locking groove 16 and the protrusion amount R of the engaging protrusion 17, and the rack shaft 11 is provided so as not to be in pressure contact with the inner end surface 13b of the holding portion 13a in a state assembled to the end portion of the holding portion 13a. The groove depth r of the locking groove 16 is set to about 0.5 mm, and the gap c1 is set to about 0.1 mm.

  Further, the buffer member 15 has an axially outer end surface (outer end surface) that forms a substantially flat surface together with the end surface 11a of the rack shaft 11, that is, in a state where the ball joint 13 is screwed to the rack shaft 11. The holding portion 13a is disposed so as to be slightly separated from the inner end surface 13b. Further, the buffer member 15 has an inner diameter that is slightly larger than the outer diameter of the end of the rack shaft 11, and is slightly loosely fitted to the rack shaft 11 via a gap c <b> 2.

  In addition, the buffer member 15 has an annular shape that is continuous along the circumferential direction on the outer peripheral side of the end surface (inner end surface) on the axially inner side facing the end surface 3a of the rack housing 3 or the outer end surface 12a of the end cap 12 in the assembled state. A protruding portion 18 is provided, and a concave portion 19 that is a substantially cylindrical space is formed on the inner peripheral side of the annular protruding portion 18. Further, an annular groove 20 that is continuously depressed along the circumferential direction is formed on the inner end surface of the buffer member 15 so as to be adjacent to the inner circumferential side of the annular protrusion 18.

  On the other hand, on the inner peripheral edge of the end surface 3 a of the rack housing 3, a substantially cylindrical concave groove 3 b that is slightly smaller than the width in the maximum thickness direction of the buffer member 15 is formed. As a result, when the rack shaft 11 slides to the left in FIG. 10, the buffer member 15 is elastically accommodated in the concave groove 3b. In addition, although illustration is abbreviate | omitted, the concave groove similar to the said concave groove 3b is formed also in the inner periphery of the outer end surface of the said end cap 12. As shown in FIG.

  Next, the characteristic operation of the power steering apparatus according to the present embodiment will be described with reference to FIGS.

  For example, when the rack shaft 11 slides in the left direction in FIG. 10, the inner end surface 13b of the holding portion 13a of the ball joint 13 eventually comes into contact with the end surface 3a of the rack housing 3 as described above. Since the buffer member 15 is provided on the inner side in the axial direction, the annular protrusion 18 of the buffer member 15 is first provided in the rack housing 3 immediately before the maximum sliding of the rack shaft 11 as shown in FIG. It contacts the inner bottom surface 3c of the concave groove 3b.

  Subsequently, when the rack shaft 11 further advances to the left, the annular protrusion 18 gradually compresses and deforms, thereby acting to attenuate the force of the rack shaft 11. The constituent meat (volume) moves to the recess 19. As the annular projection 18 is further compressed and deformed, the elastic force of the buffer member 15, that is, the damping force against the sliding of the rack shaft 11 increases. As a result, the force of the rack shaft 11 is gradually attenuated, and as shown in FIG. 9, the buffer member 15 reaches the maximum compression deformation, and the inner end surface 13b of the holding portion 13a abuts against the end surface 3a of the rack housing 3. In contact therewith, further stroke movement of the rack shaft 11 is restricted.

  In obtaining the buffering action as described above, the buffer member 15 is disposed so as to be slightly separated from the inner end surface 13b of the holding portion 13a, and a slight gap c1 is provided on the outer periphery of the end portion of the rack shaft 11. , C2 to be fitted in a slightly loose fit state, and no load is applied until the contact with the concave groove 3b of the rack housing 3, so that all the elastic force of the buffer member 15 contributes to the buffer action. Can do.

  Further, the annular protrusion 18 is formed on the inner end surface of the buffer member 15, and only the annular protrusion 18 is brought into contact with the inner bottom surface 3 c of the concave groove 3 b of the rack housing 3 during the buffering action. The concave portion 19 formed as the annular projection 18 is projected serves as a relief groove when the annular projection 18 is elastically deformed, and the movement (volume change) of the meat due to the elastic deformation is caused by the concave portion 19. Can be absorbed. That is, since the deformation of the buffer member 15 is not suppressed by securing the room for the volume change of the buffer member 15 during the elastic deformation, all the elastic force of the buffer member 15 contributes to the buffer action. can do.

  As a result, a change in the buffering characteristic of the buffer member 15 during the buffering operation can be prevented, and a desired buffering characteristic of the buffer member 15 can be obtained. The collision noise between the inner end surface 13b of the portion 13a and the end surface 3a of the rack housing 3 can be reliably prevented.

  Further, since the buffer member 15 is fitted on the outer periphery of the end of the rack shaft 11 by engaging the engaging protrusion 17 with the locking groove 16, the holding member is held during the buffering operation. By being pressed between the inner end face 13b of the portion 13a and the end face 3a of the rack housing 3, it is compressed and deformed in the axial direction, and the volume of the buffer member 15 is moved in the radial direction by this compressive deformation. The portion 17 is deformed in a direction to enter the locking groove 16. As a result, the coupling force of the buffer member 15 to the rack shaft 11 is increased, and the axial displacement of the buffer member 15 can be prevented.

  Further, the locking groove 16 is formed within the range of the axial direction region of the rack shaft 11 into which the threaded portion 13c of the ball joint 13 is screwed, and overlaps with the threaded portion 13c in the radial direction when the ball joint 13 is mounted. By setting the position of the locking groove 16, the total thickness of the peripheral wall thickness of the rack shaft 11 and the radial thickness of the screw portion 13c at the portion where the locking groove 16 is formed is the rack. It is ensured larger than the thickness of the peripheral wall at the other part of the shaft 11. As a result, the locking groove 16 is formed on the outer peripheral surface of the rack shaft 11 formed to be thin, but the formation of the locking groove 16 prevents a decrease in radial rigidity at the end of the rack shaft 11. Has been.

  In the description of the buffering action of the buffer member 15, only the case where the rack shaft 11 slides in the left direction in FIG. 10 is described. However, even when the rack shaft 11 slides in the right direction in FIG. The only difference is that the inner end surface 13b of the holding portion 13a abuts on the outer end surface 12a of the end cap 12, and the same effect as that in the case of abutting on the end surface 3a of the rack housing 3 can be obtained with respect to the buffering action. .

  Therefore, according to this embodiment, each buffer member 15 is structured to be fitted to the outer periphery of both end portions of the rack shaft 11 via the respective locking grooves 16, so that the shaft of the rack shaft 11 is provided. Both end surfaces in the direction can be continuously formed in a flat annular shape, and sufficient rigidity of both end portions of the rack shaft 11 can be ensured. As a result, even if a relatively large external force acts in the radial direction of the rack shaft 11, such as when a load is input obliquely from the wheel to the rack shaft 11 via the tie rod 14, So-called opening at both ends can be prevented.

  Further, by fitting the buffer member 15 to the rack shaft 11 in a loosely fitted state, it is possible to improve the assembling workability of the buffer member 15 while ensuring good buffer characteristics of the buffer member 15 as described above. I can plan.

  FIG. 11 shows a second embodiment of the steering apparatus according to the present invention, the basic configuration is the same as that of the first embodiment, and the difference is the engagement protrusion of the buffer member 15. 17 has a tightening margin with respect to the locking groove 16 of the rack shaft 11, that is, the protrusion amount R of the engaging protrusion 17 is set larger than the groove depth r of the locking groove 16, and the engaging protrusion 17 is elastically fitted into the locking groove 16 (the gap c1 is zero). The groove depth d of the annular concave groove 20 is extended along the axial direction and is larger than the diameter D of the engagement protrusion 17. That is, the annular groove 20 is set so that the position of the maximum groove depth is on the axially outer side (right side in the drawing) than the engaging protrusion 17.

  Therefore, according to this embodiment, since the engaging protrusion 17 is fitted to the locking groove 16 with a tightening margin, the buffer member 15 is firmly fixed to the rack shaft 11. Accordingly, the axial displacement of the buffer member 15 can be reliably prevented.

  In addition, since the groove depth of the annular groove 20 is relatively large, when the annular protrusion 18 is elastically (compressed) deformed during the buffering action, the annular protrusion 18 associated with this deformation is deformed. The movement of the meat (volume change) can be reliably absorbed by the annular groove 20. Thereby, even if the engagement protrusion 17 is fitted to the locking groove 16 with a tightening margin, the buffer member 15 can secure a room for volume change due to the elastic deformation, and the elastic member Since the deformation is not suppressed, all the elastic force of the buffer member 15 can contribute to the buffer action. As a result, a desired buffering characteristic of the buffer member 15 is obtained during the buffering operation.

  The technical ideas other than the invention described in each of the claims ascertained from the respective embodiments will be described below.

  The shock absorbing member is disposed so as not to receive stress in a state where it does not contact the other end surface in the axial direction of the housing or the outer end surface of the end member. Steering device.

  According to this invention, since the buffer member has a structure in which no load is applied in a state where it does not contact the other axial end surface of the housing or the outer end surface of the end member, a change in the buffer characteristic of the buffer member due to other external force Thus, the desired cushioning characteristics of the cushioning member can be obtained.

(2) While each of the locking grooves is formed in an annular shape on the outer periphery of both ends of the rack shaft,
On the inner peripheral portion of each buffer member, an annular engagement protrusion is formed, which is fitted to each locking groove with a slight gap,
Each of the buffer members is fitted into each of the locking grooves of the rack shaft in a loosely fitted state while the axial positions of the outer end surface in the axial direction and the end surface of the rack shaft are substantially matched. A steering device according to item (1).

  According to this invention, each of the buffer members is fitted into the respective locking grooves of the rack shaft in a loosely fitted state while the axial positions of the outer end surface in the axial direction and the end surface of the rack shaft are substantially matched. Thereby, in the mounting state with respect to the rack shaft, compressive deformation between the contact surface of the ball joint and the inner surface on the axially inner side of the locking groove is prevented. Thereby, since the buffer member is always unloaded in a state where it does not contact the other end surface in the axial direction of the housing or the outer end surface of the end member, all of its elastic force can contribute to the buffer action, It is possible to prevent a change in the buffer characteristics due to the buffer action.

(3) While each of the locking grooves is formed in an annular shape on the outer periphery of both ends of the rack shaft,
On the inner peripheral portion of each buffer member, an annular engagement protrusion that fits into each locking groove is formed,
The steering apparatus according to claim 3, wherein the buffer members are fitted to the outer circumferences of both end portions of the rack shaft by fitting the engagement protrusions to the locking grooves.

  According to this invention, the buffer member is compressed and deformed by being sandwiched between the contact surface of the ball joint and the other axial end surface of the housing or the outer end surface of the end member during the buffer operation. The protrusion is elastically deformed in the direction of entering the locking groove. As a result, the coupling force between the buffer member and the rack shaft is increased, and the axial displacement of the buffer member can be prevented.

  [Claim 4] The steering according to claim 1 or 2, wherein an annular protrusion is formed on an outer peripheral side of an end face of the buffer member facing the other end face in the axial direction of the housing or an outer end face of the end member. apparatus.

  According to this invention, when only the annular protrusion is brought into contact with the other axial end surface of the housing or the outer end surface of the end member, when the annular protrusion is elastically deformed, Since the space on the peripheral side serves as a relief groove and the movement of the meat (volume change) due to the deformation of the annular protrusion can be absorbed by the space, a desired buffer characteristic can be obtained.

(5) While forming the rack shaft in a substantially cylindrical shape, and forming a female screw portion on the inner peripheral surface of both ends of the rack shaft,
On the outer periphery of the coupling portion with the rack shaft in the ball joint, a male screw portion that is screwed into the female screw portion is formed,
The steering device according to claim 3, wherein the locking groove is formed in a range of an axial direction region of the rack shaft into which the male screw portion of the ball joint is screwed.

  According to the present invention, in the mounted state of the ball joint, the locking groove overlaps with the coupling portion of the ball joint in the radial direction, so the thickness of the portion where the locking groove is formed and the ball joint Since the total thickness with the wall thickness is larger than the wall thickness of the other part of the rack shaft, the radial rigidity at the end of the rack shaft does not decrease with the formation of the locking groove. .

  (6) The steering apparatus according to claim 1 or 2, wherein the engaging means is configured by engaging protrusions formed on outer peripheral surfaces of both ends of the rack shaft.

  According to this invention, since the thickness of the peripheral wall of the both ends of the rack shaft is not reduced, the rigidity of the end of the rack shaft can be reliably ensured. In addition, since the engaging protrusion is formed of metal integrally with the rack shaft, the buffer member can be more firmly fixed.

  The present invention is not limited to the configuration of each of the embodiments described above, and for example, the shape and size of the buffer member 15 can be freely changed according to the specification and size of the steering device.

  Further, the engaging protrusion 17 of the buffer member 15 may be formed intermittently along the circumferential direction as shown in FIG. 12, in addition to being formed continuously in the circumferential direction as shown in FIG. The same operational effects as those of the above embodiments can be obtained. In this case, the assembling work of the buffer member 15 to the rack shaft 11 is facilitated as compared with the case where the engaging protrusions 17 are continuously formed in the circumferential direction.

  Furthermore, the engagement protrusion 17 of the buffer member 15 is abolished, and the locking groove 16 is formed in the buffer member 15 to have a groove width equal to the axial width. It is possible to fit in the locking groove 16. In this case, the processing man-hour of the buffer member 15 can be reduced, the manufacturing cost can be reduced, and the coupling area of the buffer member 15 fitted in the locking groove 16 is expanded. The mounting rigidity of the buffer member 15 can be improved, and the axial displacement of the buffer member 15 can be more reliably prevented.

  As another example of each embodiment, although not shown, the end cap 12 is provided on the inner peripheral side of the outer end (the right end in FIG. 10) of the rack housing 3, and the cushioning member 15 is provided. Is not brought into contact with the end surface 3a of the rack housing 3 but with the outer end surface 12a of the end cap 12 in the same manner as the outer end portion (left end side in FIG. 10) of the power cylinder 4, thereby restricting the amount of movement in the axial direction. Even in this case, the same effects as those of the above embodiments can be obtained.

  Further, the engagement groove 16 and the engagement protrusion 17 are reversed, and an annular engagement that is continuous or intermittent in the circumferential direction instead of the engagement grooves 16 on the outer peripheral surfaces of both ends of the rack shaft 11. While forming the mating protrusions respectively, on the inner peripheral surface of the buffer member 15, locking grooves corresponding to the engaging protrusions are formed instead of the respective engaging protrusions 17, and the same as in the above embodiments. It is also possible to fit and fix the buffer member 15 to the outer periphery of both ends of the rack shaft 11. In this case, since the thickness of the peripheral wall at both ends of the rack shaft 11 is not reduced, the rigidity of the end of the rack shaft 11 can be reliably ensured, and the engaging protrusion Since the rack shaft 11 is integrally formed of metal, the buffer member 15 can be more firmly fixed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a first embodiment of a steering apparatus according to the present invention, and is a longitudinal sectional view in the vicinity of an outer end portion of a rack housing for explaining main parts of the present invention. It is the sectional view on the AA line of FIG. FIG. 2 is an enlarged view of a main part in the vicinity of an outer end portion of a rack housing, illustrating a first embodiment of the steering device and illustrating details of a main part of the present invention. FIG. 3 is a half sectional view of an end portion of the rack shaft showing the first embodiment of the steering device. It is the arrow view seen from the C direction of FIG. It is a front view of the buffer member which shows 1st Embodiment of the steering apparatus. It is the DD sectional view taken on the line of FIG. FIG. 2 is an enlarged view of the vicinity of a portion B in FIG. 1 illustrating the first embodiment of the steering device and illustrating the start of the buffering action of the buffer member according to the present invention. FIG. 2 is an enlarged view of the vicinity of a portion B in FIG. 1 illustrating the first embodiment of the steering device and illustrating the end of the buffering action of the buffer member according to the present invention. 1 is an overall view of a steering device showing a first embodiment of the steering device. It is a principal part enlarged view of the outer end part vicinity of the rack housing which shows 2nd Embodiment of the steering apparatus and demonstrates the detail of the principal part of this invention. It is a front view of the buffer member which shows the other example of the shape of an engaging protrusion.

Explanation of symbols

3 ... Rack housing (housing)
3a: End surface of the rack housing (the other end surface in the axial direction of the housing)
8 ... Cylinder tube (housing)
DESCRIPTION OF SYMBOLS 11 ... Rack axis | shaft 11a ... End surface 12 of a rack axis | shaft ... End cap (end member)
12a ... Outer end surface of end cap (outer end surface of end member)
13 ... Ball joint (shaft coupling)
13b ... Outer bottom surface of holding part (inner end surface of shaft coupling)
14 ... Tie rod 15 ... Buffer member 16 ... Locking groove

Claims (3)

A rack shaft disposed in the housing so as to be movable in the axial direction;
A shaft coupling coupled to both ends of the rack shaft;
A tie rod that is rotatably supported by the shaft coupling and is linked to a wheel;
An end member provided at one axial end of the housing and slidably supporting the rack shaft;
The shaft joints are disposed at both ends of the rack shaft, and contact the outer end surface of the other end in the axial direction of the housing or the outer end surface of the end member during the maximum sliding of the rack shaft, thereby causing collision of the shaft joint. A buffer member for buffering,
Engaging means for engaging and holding the buffer member is provided between the outer peripheral surfaces of both ends of the rack shaft and the buffer member, and both end surfaces in the axial direction of the rack shaft are continuously formed in a flat annular shape. A steering apparatus characterized by the above. A rack shaft disposed in the housing so as to be movable in the axial direction;
A shaft coupling coupled to both ends of the rack shaft;
A tie rod that is rotatably supported by the shaft coupling and is linked to a wheel;
End members respectively provided at both axial ends of the housing and slidably supporting the rack shaft;
A buffer member disposed at both ends of the rack shaft and buffering a collision of the shaft joint by abutting against an outer end surface of the end member when the rack shaft is slid maximum;
Engaging means for engaging and holding the buffer member is provided between the outer peripheral surfaces of both ends of the rack shaft and the buffer member, and both end surfaces in the axial direction of the rack shaft are continuously formed in a flat annular shape. A steering apparatus characterized by the above. 3. The steering device according to claim 1, wherein a part of the engaging means is formed by a locking groove formed on an outer peripheral surface of both ends of the rack shaft. 4.

Images