JP5062465B2 - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive steering device capable of suppressing the generation of noise. <P>SOLUTION: The steering device 1 is a rack and pinion type, and elastically supports first and second rack bushes 28, 29 at first and second end portions 15a, 15b of a rack housing 15. The first rack bush 28 on a side relatively close to a pinion shaft 13 has a supporting hole 34 slidably supporting an end portion 14b of a rack shaft 14 in an axial direction S. An elastic member 31 energizes the rack shaft 14 in a predetermined energizing direction F toward the pinion shaft 13 through the first rack bush 28. An inner peripheral surface S of the supporting hole 34 presses the rack shaft 14 in the energizing direction F, thereby regulating the movement of the rack shaft 14 in a direction C orthogonal to the energizing direction F. Backlash between the rack shaft 14 and the pinion shaft 13 can be decreased, and a conventional rack shaft supporting device is abolished. Consequently, a structure can be simplified. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a steering device.

A rack and pinion type steering apparatus has a pinion shaft and a housing that holds the rack shaft. The housing has a cylindrical shape extending in the axial direction of the rack shaft, and the rack shaft passes through the interior of the housing (see, for example, Patent Document 1).
The rack shaft is supported by a rack shaft support device at an intermediate portion of the housing in the axial direction of the rack shaft. The rack shaft support device has a support yoke that supports the rack shaft so as to be slidable in the axial direction. The support yoke is held in a holding hole in the housing so as to be movable in a direction perpendicular to the axial direction of the rack shaft, and is biased by a spring in this direction so that the rack shaft is directed toward the pinion shaft. Energized.

The rack shaft is received by an annular rack bush at the end of the housing in the axial direction of the rack shaft.
In Patent Document 1, the rack bush receives the rack shaft via a plurality of elastically biased balls. That is, the rack shaft is supported so as to be movable in the axial direction in a state where three balls arranged at equal intervals in the circumferential direction of the rack shaft are in rolling contact with the corresponding axial grooves of the rack shaft. Between each ball and the rack bush, an elastic member for biasing the rack shaft in the radial direction is interposed. These elastic members cooperate with each other to urge the rack shaft so that the center of the rack shaft coincides with the center of the housing.
JP 2004-161117 A

  When the rack shaft support device as described above is provided, the manufacturing cost increases due to an increase in the number of parts. In addition, the support yoke may rattle in the holding hole, resulting in abnormal noise. In order to suppress the occurrence of this abnormal noise, it is necessary to strictly manage the gap between the support yoke and the holding hole to a predetermined minute amount. As a result, the assembly cost increases, and also from this point, the manufacturing cost Was high. Moreover, since the rack bush of patent document 1 has a some ball | bowl, a structure is complicated and expensive.

  Therefore, an object of the present invention is to provide an inexpensive steering device that can suppress the occurrence of abnormal noise.

The present invention relates to a rack-and-pinion type steering apparatus in which a rack shaft is inserted, a cylindrical housing having first and second ends in the axial direction, and first and second ends of the housing. Of these, a rack bush that is held at a first end relatively close to the pinion shaft and has a support hole that slidably supports the end of the rack shaft in the axial direction, and is connected to and integrated with the rack bush. And an elastic member that urges the rack shaft in a predetermined urging direction toward the pinion shaft via the rack bush, the rack bush being have been displaceably supported in a predetermined urging direction, the housing has a holding hole for holding the rack bush, a part of the inner peripheral surface of the holding hole, the elastic Be formed recess for accommodating the timber, an elastic member housed in said recess, while being elastically positioned by the recess, the movement in the circumferential direction of the rack bushing for elastically regulated It is characterized by.

  According to the present invention, the elastic member urges the rack shaft toward the pinion shaft through the rack bush, which is an essential configuration, thereby suppressing backlash between the rack shaft and the pinion shaft. The occurrence of abnormal noise can be suppressed. The conventional rack shaft support device having a complicated structure using the support yoke can be abolished, and the manufacturing cost can be reduced by reducing the component cost and the assembly cost.

Further, it is possible to regulate the urging direction of the elastic member accommodated in the concave portion. Further, since the elastic member is also used as a detent for the rack bush, the structure is simplified.
In the present invention, the inner peripheral surface of the support hole of the rack bush has a pair of restricting portions for restricting movement of the rack shaft in a direction orthogonal to the predetermined urging direction, and the predetermined urging direction. and a pressing portion for pressing the back of the rack teeth of the rack shaft by the urging force of the elastic member to, the pair of restricting portions and a pressing portion, the rack shaft may have been supported at three points (claim 2 ). In this case, rattling of the rack shaft with respect to the urging direction and the above-described orthogonal direction is reliably prevented.

In the present invention, each of the pair of restricting portions may include a flat surface parallel to the predetermined urging direction (Claim 3 ). In this case, the movement of the rack shaft in the predetermined urging direction can be smoothly guided by the restricting portion.
Further, in the present invention, the inner peripheral surface of the supporting hole of the rack bush may have provided a convex portion corresponding to at least one of the pair of restricting portions and a pressing portion (claim 4). In this case, the contact area between the rack bush and the rack shaft can be reduced, and the movement resistance of the rack shaft in the axial direction can be reduced.

In the present invention, the inner peripheral surface of the support hole of the rack bush may include a facing portion that faces the pressing portion, and a predetermined gap may be provided between the facing portion and the rack shaft. (Claim 5 ). In this case, it contributes to the reduction of the movement resistance of the rack shaft in the axial direction. Further, since the rack shaft can be easily passed through the rack bush, the steering device can be easily assembled.

Also, in the present invention, the inner peripheral surface of the holding hole, between the outer peripheral surface of the rack bush, an annular O-ring is interposed, by the O-ring, the rack shaft in some cases is elastically supported (Claim 6 ). In this case, with respect to the biasing direction, the elastic member can bias the rack shaft via the rack bush. In addition, with respect to the orthogonal direction, the occurrence of rattling of the rack bush can be suppressed by the elastic repulsive force of the O-ring, and these effects can be achieved with a simple structure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Although the present embodiment will be described based on the case where the steering device is a power steering device, the present invention is not limited thereto, and may be a manual steering device, for example.
FIG. 1 is a schematic diagram showing a schematic configuration of a steering apparatus according to an embodiment of the present invention. Referring to FIG. 1, a steering device 1 includes a steering shaft 4 that transmits a steering torque applied to a steering wheel 3 as a steering member, and a rack for steering the steered wheels 2 by the steering torque from the steering shaft 4. It has a steering mechanism 5 composed of an and pinion mechanism, and an intermediate shaft 6 that is provided between the steering shaft 4 and the steering mechanism 5 and transmits a rotation therebetween.

  The steering shaft 4 is inserted into the steering column 7 and is rotatably supported by the steering column 7. The steering column 7 is supported on the vehicle body 9 via a bracket 8. A steering wheel 3 is connected to one end of the steering shaft 4. An intermediate shaft 6 is connected to the other end of the steering shaft 4. The steering wheel 3 and the intermediate shaft 6 are interlocked.

The intermediate shaft 6 includes a power transmission shaft 10, a universal joint 11 provided at one end of the intermediate shaft 6, and a universal joint 12 provided at the other end of the intermediate shaft 6.
The steering mechanism 5 supports a pinion shaft 13 as an input shaft, a rack shaft 14 as a steered shaft extending in the lateral direction of the automobile (a direction orthogonal to the straight traveling direction), the pinion shaft 13 and the rack shaft 14. And a rack housing 15. The pinion teeth 13a of the pinion shaft 13 and the rack teeth 14a of the rack shaft 14 mesh with each other.

  The pinion shaft 13 is rotatably supported by the rack housing 15. The rack shaft 14 is supported by the rack housing 15 so as to be linearly reciprocable in the axial direction S. The rack housing 15 is fixed to the vehicle body 9. Both end portions 14 b of the rack shaft 14 in the axial direction S of the rack shaft 14 protrude from both end portions 15 a and 15 b of the rack housing 15. A pair of ball joint units 26 as joint members are provided at both end portions 14b. Corresponding steered wheels 2 are linked to each ball joint unit 26 via a tie rod 27 and a knuckle arm (not shown).

When the steering wheel 3 is steered, the steering torque is transmitted to the steering mechanism 5 via the steering shaft 4 and the intermediate shaft 6. The pinion shaft 13 rotates in conjunction with the rotation of the steering wheel 3, and the rack shaft 14 moves along the axial direction S accordingly. Thereby, the steering wheel 2 can be steered.
The steering device 1 can obtain a steering assist force according to the steering torque. That is, the steering device 1 includes a torque sensor 16 that detects steering torque, an ECU (Electronic Control Unit) 17 as a control unit, an electric motor 18 for assisting steering, and a speed reducer 19 as a transmission device. And have. In the present embodiment, the electric motor 18 and the speed reducer 19 are provided in association with the steering column 7.

The torque sensor 16 detects a steering torque that acts on the steering shaft 4 from the steering wheel 3. The torque detection result is given to the ECU 17. The ECU 17 controls the electric motor 18 based on the above torque detection result, a vehicle speed detection result given from a vehicle speed sensor (not shown), and the like.
When the steering wheel 3 is operated, the steering torque is detected by the torque sensor 16, and the electric motor 18 generates a steering assist force according to the torque detection result and the vehicle speed detection result. The steering assist force is transmitted to the pinion shaft 13 via the speed reducer 19. At the same time, the movement of the steering wheel 3 is also transmitted to the steering mechanism 5. As a result, the steering wheel 2 is steered and the steering is assisted.

The steering device 1 of the present embodiment is configured as a rack and pinion type steering device. That is, the steering mechanism 5 includes the pinion shaft 13 described above, the long rack shaft 14 described above, and a rack housing 15 serving as a housing that accommodates the axial center of the rack shaft 14 and is supported by the vehicle body 9. is doing.
The rack shaft 14 is a long rod-like member, and is formed in a circular cross section such as a circular cross section. The rack shaft 14 is a part with respect to the axial direction S, a first part where the rack teeth 14a are formed, and a remaining part excluding the first part, and the rack teeth 14a are formed. And no second part. The outer peripheral surface of the first portion has a curved portion having a circular arc cross section and a flat portion parallel to the axial direction S. Rack teeth 14a are formed on the flat portion. The outer peripheral surface of the second portion has a circular cross section.

The rack housing 15 has a cylindrical shape and extends along the axial direction S of the rack shaft 14. A rack shaft 14 is inserted into the rack housing 15. The rack housing 15 has first and second end portions 15a and 15b in the longitudinal direction (corresponding to the axial direction S), and an intermediate portion 15c disposed between the both end portions 15a and 15b. ing.
The intermediate portion 15c of the rack housing 15 rotatably supports the pinion shaft 13 via a bearing (not shown). The pinion shaft 13 is disposed so as to be relatively close to the first end portion 15a, and is disposed so as to be relatively far from the second end portion 15b. In the intermediate portion 15c, the conventional rack shaft support device is abolished.

The steering mechanism 5 includes first and second rack bushes 28 and 29 that support the rack shaft 14 slidably in the axial direction S, a pair of rack stoppers 30, and a first rack bush 28. And an elastic member 31 for energizing.
The first rack bush 28, the elastic member 31, and the one rack stopper 30 are held by the first end 15 a that is relatively close to the pinion shaft 13. The second rack bush 29 and the other rack stopper 30 are held by the second end 15b.

The steering device 1 according to the present embodiment is configured in the same manner with respect to the peripheral portions of both end portions 14b of the rack shaft 14 except for the first and second rack bushes 28 and 29 and the elastic member 31, and is similar to each other. About the structure, the same code | symbol is attached | subjected and description is abbreviate | omitted.
2 is a cross-sectional view of a main part D2 of the steering mechanism 5 of the steering device 1 shown in FIG. 1, and shows a cross section taken along S2-S2 shown in FIG. 3 is a cross-sectional view taken along a line S3-S3 in FIG.

The first end 15 a of the rack housing 15 has a holding hole 32. The holding hole 32 has an inner peripheral surface 32a that forms a cylindrical surface, and a side wall 32b that extends radially inward from one end of the inner peripheral surface 32a. Moreover, the recessed part 33 is formed in the internal peripheral surface 32a.
A rack stopper 30 is fixed to the opening end of the holding hole 32. The rack stopper 30 has an annular shape and abuts against a part of the ball joint unit 26 (see FIG. 1), thereby restricting the range of movement of the rack shaft 14 relative to the rack housing 15 in the axial direction S of the rack shaft 14.

The first rack bush 28 is sandwiched between the rack stopper 30 and the side wall 32b in the axial direction S of the rack shaft 14. The movement of the first rack bush 28 in one direction in the axial direction S is restricted by the side wall 32b of the holding hole 32, and the movement of the first rack bush 28 in the other direction in the axial direction S is restricted by the rack stopper 30. It is regulated.
The recess 33 is formed in a part of the inner peripheral surface 32 a of the holding hole 32 with a predetermined depth, and is open to the inside of the holding hole 32. The recess 33 is disposed at the center of the inner peripheral surface 32 a of the holding hole 32 with respect to the axial direction S of the rack shaft 14. Further, when viewed along the axial direction S of the rack shaft 14, the recess 33 and the pinion shaft 13 are disposed on opposite sides of the rack shaft 14.

The elastic member 31 is accommodated in the recess 33. The bottom surface of the recess 33 receives and holds the elastic member 31. Further, the side wall of the recess 33 restricts the movement of the elastic member 31 in the circumferential direction T of the rack shaft 14.
The elastic member 31 is a leaf spring formed of a synthetic resin material as an elastic body. This leaf spring has a pair of surfaces on opposite sides. The leaf spring has a curved shape when viewed from the axial direction S of the rack shaft 14. One surface is convexly curved and the other surface is concavely curved. Both end portions of the concavely curved surface are connected to the outer peripheral surface 39 of the first rack bush 28 and fixed. A gap is formed between the center portion of the concavely curved surface and the first rack bush 28 as an opposing portion. The central portion of the convexly curved surface is connected to and abuts the bottom surface of the concave portion 33. Both end portions of the convexly curved surface are in contact with the side wall of the concave portion 33. In addition, the direction of the elastic member 31 is reversed, the central portion of the convexly curved surface is connected to the outer peripheral surface 39 of the first rack bush 28, and both end portions of the concavely curved surface are the concave portions 33. It is also conceivable that it is connected to the bottom surface.

  The elastic member 31 is interposed between the bottom surface of the recess 33 and the first rack bush 28 in a state where the elastic member 31 is subjected to an elastic bending deformation that increases the curvature radius of the curve. Accordingly, the elastic member 31 elastically presses and urges the first rack bush 28 and urges the rack shaft 14 in a predetermined urging direction F via the first rack bush 28. Here, the predetermined urging direction F is a direction orthogonal to the axial direction S, in which the rack shaft 14 and the pinion shaft 13 are aligned with each other, and the rack shaft 14 approaches the pinion shaft 13. .

The elastic member 31 accommodated in the recess 33 is connected to the first rack bush 28 so as to restrict the movement of the first rack bush 28 in the circumferential direction T. Specifically, the elastic member 31 and the first rack bush 28 are integrally formed of a synthetic resin member as a single member.
The first rack bush 28 has a cylindrical shape. The center axis of the cylinder of the first rack bush 28 is arranged in parallel to the axial direction S of the rack shaft 14. The first rack bush 28 is formed of a synthetic resin member as a material having excellent sliding characteristics.

The first rack bush 28 has a support hole 34. The rack shaft 14 passes through the support hole 34. The support hole 34 has an inner peripheral surface 35. The inner peripheral surface 35 supports the first portion of the end portion 14b of the rack shaft 14 so as to be slidable in the axial direction S.
The inner peripheral surface 35 of the support hole 34 is a pair of restricting portions 36 that restrict the movement of the rack shaft 14, a pressing portion 37 that presses the rack shaft 14 in a predetermined biasing direction F, and an opposing surface that faces the pressing portion 37. Part 38. The inner peripheral surface 35 is formed by connecting edges of the pair of restricting portions 36, the pressing portion 37, and the facing portion 38 to each other. Further, the rack shaft 14 is supported at three points by the pair of regulating portions 36 and the pressing portion 37.

  The pair of restricting portions 36 oppose each other in the radial direction of the rack shaft 14 as the direction C orthogonal to the urging direction F. The rack shaft 14 is disposed between the pair of restricting portions 36. The pair of restricting portions 36 restricts the movement of the rack shaft 14 to both sides in the orthogonal direction C described above. Each restricting portion 36 is formed by a flat surface parallel to a predetermined biasing direction F and parallel to the axial direction S, and is in line contact with the rack shaft 14.

The distance between the pair of restricting portions 36 is a distance equal to or slightly smaller than the diameter of the outer peripheral surface of the rack shaft 14 in the state of a single component of the first rack bush 28, The rack shaft 14 is in contact with a tightening margin.
The pressing portion 37 is formed on a flat surface and is in line contact with the rack shaft 14. The flat surface of the pressing portion 37 is a surface that is orthogonal to the predetermined biasing direction F and is parallel to the axial direction S. In a cross section perpendicular to the axial direction S of the rack shaft 14, the pressing portion 37 receives a biasing force of the elastic member 31 in a predetermined biasing direction F and presses the back surface 14 c of the rack teeth 14 a of the rack shaft 14. Yes. The rear surface 14c is a surface that is opposite to the rack tooth 14a in the radial direction R and extends in the axial direction S when viewed from the axial direction S of the rack shaft 14, and the rack teeth 14a are formed in the axial direction S. And the portion where the rack teeth 14a are not formed.

The facing portion 38 and the pressing portion 37 face each other in a predetermined biasing direction F. The facing portion 38 is formed on a concave curved surface. A predetermined amount of gap 40 is formed between the facing portion 38 and the rack teeth 14 a on the outer peripheral surface of the rack shaft 14.
A predetermined amount of gap is formed between the outer peripheral surface 39 of the first rack bush 28 and the inner peripheral surface 32a of the holding hole 32, and an annular O-ring 41 is interposed in this gap. The O-ring 41 surrounds the first rack bush 28 and is elastically compressed and deformed, and elastically supports the rack shaft 14 via the first rack bush 28. Accordingly, the first rack bush 28 is supported so as to be displaceable in the holding hole 32 in an arbitrary radial direction R of the rack shaft 14.

  For example, a plurality of, for example, two annular grooves are formed on the outer peripheral surface 39 of the first rack bush 28. Each annular groove extends in the circumferential direction T at a predetermined depth, and is disposed on both sides of the elastic member 31 at a position avoiding the elastic member 31 in the axial direction S of the rack shaft 14. An O-ring 41 is fitted in each annular groove. The O-ring 41 is formed endlessly by a rubber member or a synthetic resin member as an elastic body. With respect to the radial direction of the rack shaft 14, the O-ring 41 is interposed between the inner peripheral surface 32 a of the holding hole 32 and the outer peripheral surface 39 of the first rack bush 28 in a state of undergoing elastic compression deformation.

An annular groove for the O-ring 41 may be formed on the inner peripheral surface 32 a of the holding hole 32. Further, the outer peripheral surface 39 of the first rack bush 28 and the inner peripheral surface 32a of the holding hole 32 may be formed to face each other. Further, it is sufficient that at least one O-ring 41 is provided, and instead of the O-ring 41, a rubber plate as an elastic body may be used.
Returning to FIG. 1, the second end 15 b of the rack housing 15 has a holding hole 32. The holding hole 32 holds the second rack bush 29 in a fitted state, and the recess 33 is eliminated. The second rack bush 29 is held in the holding hole 32 similarly to the first rack bush 28 except that the elastic member 31 is not biased.

  The second rack bush 29 restricts the movement of the second portion of the end portion 14b of the rack shaft 14 with respect to the arbitrary radial direction R of the rack shaft 14 to a predetermined amount. A fastening allowance may be provided between the second rack bush 29 and the rack shaft 14, or a predetermined gap may be set. The second rack bush 29 is elastically supported by the rack housing 15 via the O-ring 41 in the same manner as the first rack bush 28, but may be fixed to the rack housing 15.

  With reference to FIGS. 1 and 2, the elastic member 31 resists the elastic repulsive force of the O-ring 41 or cooperates with the elastic repulsive force with respect to the predetermined urging direction F. The rack bush 28 is pressed, and consequently the rack shaft 14 is pressed. At this time, the second rack bush 29 as a fulcrum receives the other end 14b of the rack shaft 14, and the back teeth of the rack teeth 14a of the rack shaft 14 and the pinion teeth 13a of the pinion shaft 13 are removed from each other. It is designed to mesh with each other.

  In the present embodiment, in the rack and pinion type steering apparatus 1, the rack shaft 14 is inserted, the cylindrical rack housing 15 having the first and second end portions 15 a and 15 b with respect to the axial direction S, and the rack housing Of the first and second end portions 15a and 15b, the first end portion 15a is relatively close to the pinion shaft 13, and the end portion 14b of the rack shaft 14 is slidably supported in the axial direction S. A first rack bush 28 having a support hole 34 to be supported, and an elastic member 31 that urges the rack shaft 14 in a predetermined urging direction F toward the pinion shaft 13 via the first rack bush 28. The first rack bush 28 is supported by the rack housing 15 so as to be displaceable in a predetermined urging direction F.

  As a result, the elastic member 31 urges the rack shaft 14 toward the pinion shaft 13 via the first rack bush 28 as a rack bush, which is an essential configuration, and thereby the rack shaft 14 and the pinion shaft are urged. It is possible to suppress the backlash between the two and the generation of abnormal noise. The conventional rack shaft support device having a complicated structure using the support yoke can be abolished, and the manufacturing cost can be reduced by reducing the component cost and the assembly cost.

Further, since the first rack bush 28 is disposed at the first end portion 15a on the side close to the pinion shaft 14, the rack shaft 14 can be effectively urged toward the pinion shaft 13. .
Further, since the rack shaft 14 is inserted through the support hole 34 at the center of the first rack bush 28, the first rack bush 28 is urged by the elastic member 31 in a predetermined urging direction F. Even when the rack housing 15 is held so as to be displaceable in the predetermined urging direction F, the attitude of the first rack bush 28 is regulated by the rack shaft 14 inserted through the center portion, Compared with the conventional support yoke, the occurrence of the tilting and rattling of the first rack bush 28 is suppressed. As a result, it is not necessary to strictly manage the gap between the inner peripheral surface 32a of the holding hole 32 of the rack housing 15 and the outer peripheral surface 39 of the first rack bush 28, and the manufacturing cost can be reduced.

Further, with the abolition of the conventional rack shaft support device, the movement resistance of the rack shaft 14 in the axial direction S can be reduced.
Further, since the first and second rack bushes 28 and 29 are slidably in contact with the rack shaft 14, the structure can be simplified as compared with the case where a ball is interposed between the first and second rack bushes 28 and 29.
Furthermore, the first and second rack bushes 28 and 29 both restrict the movement of the rack shaft 14 in the direction C perpendicular to each other. Thereby, when the rack shaft 14 is moved in the axial direction, the first and second rack bushes 28 and 29 are unlikely to rattle, and the occurrence of abnormal noise due to the rattling can be suppressed.

  In the present embodiment, the rack housing 15 has a holding hole 32 that holds the first rack bush 28, and a recess for accommodating the elastic member 31 in a part of the inner peripheral surface 32 a of the holding hole 32. 33 is formed. In this case, the urging direction F of the elastic member 31 accommodated in the recess 33 can be restricted. Further, since the portion 32c of the inner peripheral surface 32a around the recess 33 receives the first rack bush 28, the first rack bush 28 can be prevented from excessively deforming the elastic member 31.

  The inner peripheral surface 35 of the support hole 34 of the first rack bush 28 has a pair of restricting portions 36 that restrict the movement of the rack shaft 14 in the direction C perpendicular to the predetermined biasing direction F, and a predetermined amount. And a pressing portion 37 that presses the back surface 14c of the rack tooth 14a of the rack shaft 14 by the biasing force of the elastic member in the biasing direction F. The rack shaft 14 has three points by the pair of regulating portions 36 and the pressing portion 37. It is supported. In this case, the first rack bush 28 can reliably prevent the rack shaft 14 from rattling in the urging direction F and the orthogonal direction C described above.

Further, each of the pair of restricting portions 36 includes a flat surface parallel to the predetermined biasing direction F. In this case, the movement of the rack shaft 14 in the predetermined urging direction F can be smoothly guided by the restricting portion 36. Further, since the restricting portion 36 does not need to receive the urging force by the elastic member 31, it is preferable to hold the rack shaft 14 without rattling as a result of being hard to be worn.
The inner peripheral surface 35 of the support hole 34 of the first rack bush 28 includes a facing portion 38 that faces the pressing portion 37. A predetermined gap 40 is provided between the facing portion 38 and the rack shaft 14. In this case, it contributes to the reduction of the movement resistance of the rack shaft 14 in the axial direction S. Moreover, since the rack shaft 14 can be easily passed through the first rack bush 28, the steering device 1 can be easily assembled.

  Further, the elastic member 31 accommodated in the recess 33 is connected to the first rack bush 28 so as to restrict the movement of the first rack bush 28 in the circumferential direction T. In this case, since the elastic member 31 is also used as a detent for the first rack bush 28, the structure is simplified. Here, as the connection between the elastic member 31 and the first rack bush 28, these are integrally formed by a single member, these are integrally formed by a plurality of members, and they are fixed to each other. Either of them may be integrated.

  An annular O-ring 41 is interposed between the inner peripheral surface 32 a of the holding hole 32 and the outer peripheral surface 39 of the first rack bush 28, and the rack shaft 14 is elastically supported by the O-ring 41. Yes. In this case, with respect to the urging direction F, the elastic member 31 can urge the rack shaft 14 via the first rack bush 28. In addition, with respect to the direction C orthogonal, the occurrence of rattling of the first rack bush 28 can be suppressed by the elastic repulsive force of the O-ring 41, and further, these effects can be achieved with a simple structure. .

In this way, suppression of rattling is achieved by elastically supporting the first rack bush 28, so that the clearance between the inner peripheral surface 32a of the holding hole 32 of the rack housing 15 and the first rack bush 28 is It is not necessary to manage to a predetermined minute amount, and the manufacturing cost can be reduced.
Moreover, the following modifications can be considered about this embodiment. In the following description, differences from the above-described embodiment will be mainly described, and the same components are denoted by the same reference numerals and description thereof is omitted.

FIG. 4 is a cross-sectional view of a main part of the steering device according to the second embodiment of the present invention. With reference to FIG. 4, in this embodiment, the elastic member 31 and the first rack bush 28 are formed separately from each other and can be separated from each other. In this case, the elastic member 31 and the first rack bush 28 can be formed of members that are optimum for each.
The elastic member 31 is received at two locations on the bottom surface of the recess 33 and is in contact with the outer peripheral surface 39 of the first rack bush 28 at one location. The elastic member 31 may be disposed in the reverse direction as in the first embodiment.

  Further, the holding hole 32 and the first rack bush 28 have a pair of engaging portions 42 and 43 as rotation stoppers that restrict relative rotation by engaging with each other. The engaging portion 42 is formed of a concave portion as a undulating portion formed in the rack housing 15. The engaging portion 43 is composed of a convex portion as an undulating portion formed on the first rack bush 28. When the engaging portions 42 and 43 engage with each other in a concave-convex manner, the first rack bush 28 is arranged in the same manner as in the first embodiment. For example, when viewed along the axial direction S, the pressing portion 37 is mounted on the rack. The pinion shaft 13 is disposed on the opposite side of the shaft 14. In addition, the uneven | corrugated relationship of the engaging parts 42 and 43 may be reverse.

FIG. 5 is a cross-sectional view of a main part of the steering device 1 according to the third embodiment of the present invention. Referring to FIG. 5, the inner peripheral surface 35 of the support hole 34 of the first rack bush 28 has a plurality of convex portions 44. In other respects, the present embodiment is the same as the first embodiment.
The inner peripheral surface 35 has a curved portion 45 formed of a cylindrical surface, and the above-described convex portion 44 that protrudes radially inward from the curved portion 45. A pair of restricting portions 36 and pressing portions 37 on the inner peripheral surface 35 of the support hole 34 of the first rack bush 28 are arranged at the tips of the three convex portions 44. The tip of each convex portion 44 is formed on a flat surface. These flat surfaces are formed in the same manner as the corresponding flat surfaces of the pair of restricting portions 36 and pressing portions 37 in the first embodiment. Further, each convex portion 44 extends over the entire length of the first rack bush 28 in the axial direction S, and the cross-sectional shape is formed constant with respect to the axial direction S.

Note that the convex portion 44 may be formed integrally with the inner peripheral surface 35, or may be formed separately and fixed to the inner peripheral surface 35. Further, the convex portion 44 may be provided corresponding to a part of the pair of regulating portions 36 and the pressing portion 37. Moreover, you may provide the convex part 44 in the internal peripheral surface 35 of the 1st rack bush 28 of 2nd Embodiment.
As described above, the inner peripheral surface 35 of the support hole 34 of the first rack bush 28 is provided with a convex portion 44 corresponding to at least one of the pair of restricting portions 36 and the pressing portion 37. In this case, the contact area between the first rack bush 28 and the rack shaft 14 can be reduced, and the movement resistance of the rack shaft 14 in the axial direction S can be reduced.

  In each of the above-described embodiments, when the first rack bush 28 is not elastically supported and is held so as to be displaceable in a predetermined urging direction F, the gap 38 is not provided, and the facing portion 38 is provided with the rack shaft 14. When at least one of the pair of regulating portions 36 and the pressing portion 37 is formed of a convex curved surface or a concave curved surface, the elastic member 31 may be held in the holding hole 32 without the concave portion 33. In addition, various design changes can be made within the scope of matters described in the claims.

It is a side view of schematic structure of the steering device of a 1st embodiment of the present invention. It is sectional drawing of the principal part of the steering apparatus shown in FIG. 1, and shows the S2-S2 cross section of FIG. It is sectional drawing of the S3-S3 cross section of FIG. It is sectional drawing of the principal part of the steering device of the 2nd Embodiment of this invention, and is equivalent to the cross section of FIG. It is sectional drawing of the principal part of the steering device of the 3rd Embodiment of this invention, and is equivalent to the cross section of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Steering device, 13 ... Pinion shaft, 14 ... Rack shaft, 14a ... Rack tooth, 14b ... End of (rack shaft), 14c ... Back surface of rack tooth, 15 ... Rack housing (housing), 15a ... First End portion, 15b ... second end portion, 28 ... first rack bush (rack bush), 31 ... elastic member, 32 ... holding hole, 32a ... inner peripheral surface, 33 ... recessed portion, 34 ... Support hole, 35 ... inner peripheral surface of (support hole), 36 ... regulating portion, 37 ... pressing portion, 38 ... opposing portion, 39 ... outer peripheral surface of (first rack bush), 40 ... gap, 41 ... O-ring 44: convex portion, C: orthogonal direction, F: biasing direction, S: axial direction, T: circumferential direction

Claims (6)

In a rack and pinion type steering device,
A cylindrical housing having a rack shaft inserted therein and having first and second ends in the axial direction;
A rack bush having a support hole that is held by a first end relatively close to the pinion shaft among the first and second ends of the housing and supports the end of the rack shaft so as to be slidable in the axial direction. When,
An elastic member that is connected and integrated with the rack bush, protrudes from the outer peripheral surface of the rack bush, and urges the rack shaft in a predetermined urging direction toward the pinion shaft via the rack bush. Prepared,
The rack bush is supported by a housing so as to be displaceable in the predetermined urging direction ,
The housing has a holding hole for holding the rack bush, and a recess for accommodating the elastic member is formed in a part of the inner peripheral surface of the holding hole,
The steering device according to claim 1, wherein the elastic member accommodated in the concave portion elastically restricts the movement of the rack bush in the circumferential direction while being elastically positioned by the concave portion . Oite to claim 1, the inner peripheral surface of the supporting hole of the rack bush, in the direction perpendicular to the predetermined biasing direction, a pair of restricting portions for restricting the movement of the rack shaft, the predetermined force of the biasing And a pressing portion that presses the back surface of the rack tooth of the rack shaft by the urging force of the elastic member in the direction, and the steering shaft is supported at three points by the pair of restriction portions and the pressing portion. apparatus. 3. The steering apparatus according to claim 2, wherein each of the pair of restricting portions includes a flat surface parallel to the predetermined urging direction. 3. The steering apparatus according to claim 2, wherein an inner peripheral surface of the support hole of the rack bush is provided with a convex portion corresponding to at least one of the pair of restricting portions and pressing portions. In any one of claims 2 to 4, the inner peripheral surface of the supporting hole of the rack bushing includes a facing portion opposed to the pressing portion, a predetermined gap between the opposing portion and the rack shaft is provided A steering apparatus characterized by being provided. In any one of claims 1 to 5, and the inner peripheral surface of the holding hole, between the outer peripheral surface of the rack bush, an annular O-ring is interposed, by the O-ring, the rack shaft is elastically supported A steering device characterized by that.

Images