JP2010254238A - Rack shaft supporting device and steering device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rack shaft supporting device having superior durability, having a simple structure, and capable of providing satisfactory feeling of steering. <P>SOLUTION: A rack shaft supporting member 18 being energized onto a rack shaft 8 side by an energizing member 20 includes a body 21 and a slide-contact plate 22 fixed on a front face 21a of the body 21. A supporting face 22a constituted by a surface of the slide-contact plate 22 supports a face 8b to be supported provided on a rear surface of a rack 8a of a rack shaft 8. The supporting face 22a and the face 8b to be supported are constituted by a plane being parallel with both of axial direction Y1 of a pinion shaft 7 and the axial direction Z1 (the direction crossing a paper surface in Fig.2) of the rack shaft 8. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rack shaft support device and a vehicle steering device including the same.

A rack and pinion type steering device is usually provided with a rack shaft support device for removing backlash between the rack and the pinion. In the rack shaft support device, the support yoke that supports the rack shaft so as to be movable in the axial direction has a receiving surface having an arcuate cross section for receiving the rear surface of the rack of the rack shaft (a surface forming a part of the cylindrical surface). Yes.
With the receiving surface having an arc cross section, the rack shaft cannot be twisted. When the rack shaft is twisted, the surface pressure becomes excessively high at the end portion of the rack in the tooth trace direction when the rack and the pinion are engaged, and the durability is lowered.

Further, as the rack shaft is twisted, the support yoke rattles so that it tilts in the holding hole, and noise is generated between the inner periphery of the holding hole and the support yoke. This may cause fretting wear.
Further, when power is transmitted from the pinion shaft to the rack shaft by a steering operation, the rack shaft is twisted, so that the response is poor, and as a result, the driver's steering feeling is poor.

  On the other hand, the ridges provided on the front surface of the support yoke are fitted into the concave grooves provided on the back surface of the rack shaft, and the urging direction of the urging member for urging the support yoke toward the rack shaft side and the rack shaft A rack shaft support device that restricts the displacement of the rack shaft in a direction orthogonal to both the axial directions has been proposed (see, for example, Patent Document 1).

JP 2008-18829 A

However, in patent document 1, it is necessary to form a protrusion and a ditch | groove, and a structure is complicated.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a rack shaft support device and a vehicle steering device that have excellent durability, good steering feeling, and simple structure.

  In order to achieve the above object, the present invention holds a rack shaft support device (15) supporting a rack shaft (8) meshing with a pinion shaft (7) in a holding hole (16) provided in a housing (17). A rack shaft support member (18) held so as to be movable back and forth in the depth direction (X1) of the hole, and a biasing member (20) housed in the housing and biasing the rack shaft support member toward the rack shaft side; The supported surface (8b) provided on the back surface of the rack of the rack shaft can be moved in the axial direction (Z1) of the rack shaft by the support surfaces (22a, 220a) provided on the rack shaft support member. And at least one of the supported surface and the supporting surface comprises a plane parallel to both the axial direction (Y1) of the pinion shaft and the axial direction of the rack shaft.

  In the present invention, for example, the torsion (twist) of the rack shaft is regulated by supporting the supported surface of the rack shaft by a support surface composed of a plane parallel to both the axial direction of the pinion shaft and the axial direction of the rack shaft. can do. Therefore, excessive surface pressure does not act on the meshing portion of the rack and the pinion, and durability can be improved. In addition, since there is no response delay when power is transmitted from the pinion shaft to the rack shaft by a steering operation, the driver's steering feeling is good. Furthermore, since at least one of the supported surface and the supporting surface is a flat surface, the structure is simple and the manufacturing cost can be reduced. Note that the displacement of the rack shaft in the direction parallel to the axial direction of the pinion shaft may be restricted by a rack bush that supports the end of the rack shaft.

  One of the supported surface and the support surface is composed of the tops of at least two convex portions (220) spaced apart from each other in a direction parallel to the axial direction of the pinion shaft, and the other is the axial direction of the pinion shaft and the rack shaft. There may be a case in which the plane is parallel to both axial directions (claim 2). If it is the top part of the at least 2 convex part spaced apart in the direction parallel to the axial direction of the pinion shaft, the twisting operation of the rack shaft can be restricted by contacting the flat surface as the other.

  Moreover, the said support surface may be comprised by the surface of the low friction sliding contact plate (22) provided in the rack shaft support member. In this case, since the rack shaft can move smoothly, the steering feeling is further improved. In addition, when the rack shaft is displaced in a direction parallel to the axial direction of the pinion shaft, the rack shaft support member can be prevented from tilting, and as a result, noise can be prevented.

A vehicle steering device that supports the rack shaft so as to be slidable in the axial direction using the rack shaft support device is preferable.
In the above description, the alphanumeric characters in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

It is a mimetic diagram showing a schematic structure of a steering device for vehicles to which a rack axis support device of one embodiment of the present invention is applied. It is sectional drawing of the principal part of the steering apparatus for vehicles to which the rack shaft support apparatus was applied. It is the figure which looked at the rack axis | shaft support member from the sliding contact board side. It is sectional drawing of the principal part of the steering apparatus for vehicles to which the rack shaft support apparatus of another embodiment of this invention was applied. It is the figure which looked at the rack axis | shaft support member which concerns on embodiment of FIG. 4 from the sliding contact board side.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
Referring to FIG. 1, a vehicle steering apparatus 1 includes a steering shaft 3 connected to a steering member 2 such as a steering wheel, an intermediate shaft 5 connected to the steering shaft 3 via a universal joint 4, an intermediate A rack as a steering shaft having a pinion shaft 7 connected to the shaft 5 via a universal joint 6 and a rack 8a meshing with the pinion 7a provided near the end of the pinion shaft 7 and extending in the left-right direction of the automobile And a shaft 8. The pinion shaft 7 and the rack shaft 8 constitute a rack and pinion mechanism A as a steering mechanism.

  The rack shaft 8 is supported in a rack housing 9 fixed to the vehicle body via a rack bush 50 which is a sliding bearing so as to be linearly reciprocable along the axial direction Z1. Both end portions of the rack shaft 8 protrude to both sides of the rack housing 9, and tie rods 10 are coupled to the respective end portions. Each tie rod 10 is connected to a corresponding steered wheel 11 via a corresponding knuckle arm (not shown).

When the steering member 2 is operated and the steering shaft 3 is rotated, this rotation is converted into a linear motion of the rack shaft 8 along the left-right direction of the automobile by the pinion 7a and the rack 8a. Thereby, the turning of the steered wheel 11 is achieved.
Referring to FIG. 2, the pinion shaft 7 has an upper part 7b and a lower part 7c with the pinion 7a interposed therebetween. The pinion shaft 7 is composed of, for example, a ball bearing and a first bearing 12 that supports the upper portion 7b of the pinion shaft 7, and a second bearing 13 that is composed of, for example, a needle roller bearing and supports the lower portion 7c of the pinion shaft 7. It is rotatably supported in the pinion housing 14. The pinion 7 a of the pinion shaft 7 and the rack 8 a of the rack shaft 8 are meshed with each other in the pinion housing 14.

  The vehicle steering device 1 is equipped with a rack shaft support device 15. The rack shaft support device 15 includes a housing 17 having a holding hole 16 formed of a circular hole, and is accommodated in the holding hole 16 so as to be slidable along the depth direction X1 of the holding hole 16 and the rear surface of the rack 8a of the rack shaft 8 A rack shaft support member 18 that slidably supports the supported surface 8b, and a sealing screw 19 as a sealing member that is screwed into and fixed to the inlet of the holding hole 16. A female screw portion 16b is formed on the inner peripheral surface 16a at the entrance of the holding hole 16, and the sealing screw 19 is screwed into the female screw portion 16b.

The rack shaft support device 15 is interposed between the rack shaft support member 18 and the sealing screw 19 and elastically biases the rack shaft support member 18 toward the rack shaft 8 side. Member 20.
The housing 17 of the rack shaft support device 15 is formed integrally with the pinion housing 14 from a single material, and is disposed on the opposite side of the pinion shaft 7 with the rack shaft 8 therebetween. The pinion housing 14 and the housing 17 are manufactured by die casting, for example.

The rear surface of the rack shaft 8 opposite to the rack 8a has an axial direction Y1 of the pinion shaft 7 (corresponding to the vertical direction in FIG. 2) and an axial direction Z1 of the rack shaft 8 (perpendicular to the paper surface in FIG. 2). The surface to be supported 8b is formed of a plane parallel to both of them.
The rack shaft support member 18 includes a hollow cylindrical main body 21 and a low friction sliding plate 22 fixed to the front surface 21 a of the main body 21. The slidable contact plate 22 is fixed to the main body 21 by fitting the convex portion 30 provided on the slidable contact plate 22 into the concave portion provided on the front surface 21 a of the main body 21. Specifically, as shown in FIG. 3, the convex portion 30 is formed of a convex strip extending in the axial direction Z <b> 1 of the rack shaft 8 (a direction orthogonal to the paper surface in FIG. 2), and is provided on the front surface 21 a of the main body 21. It is fitted to the concave groove. A gap for absorbing fluctuations is secured between the rear surface 21 b of the main body 21 of the rack shaft support member 18 and the front surface 19 a of the sealing screw 19. The outer peripheral surface 21c of the main body 21 of the rack shaft support member 18 is a cylindrical surface.

A pair of receiving grooves 23 extending in the circumferential direction and forming an annular shape are formed on the outer peripheral surface 21c of the main body 21, and each receiving groove 23 accommodates an annular elastic member 24 made of, for example, an O-ring. On the outer peripheral surface of the sealing screw 19, an annular receiving groove 25 extending in the circumferential direction is formed. In the receiving groove 25, an annular elastic member 26 made of, for example, an O-ring is accommodated.
As the sliding contact plate 22, for example, a low-friction synthetic resin plate (for example, a fluororesin plate) may be used, or a metal plate coated with a fluororesin may be used. The surface of the sliding contact plate 22 constitutes a support surface 22 a that supports the supported surface 8 b that is the back surface of the rack shaft 7. The support surface 22a is a plane parallel to both the axial direction Y1 of the pinion shaft 7 and the axial direction Z1 of the rack shaft 8 (see FIG. 3).

In the present embodiment, the description will be made based on the case where both the supported surface 8b and the supporting surface 22a are formed of planes parallel to both the axial direction Y1 of the pinion shaft 7 and the axial direction Z1 of the rack shaft 8. At least one of the supported surface 8b and the supporting surface 22a only needs to be a plane parallel to both the axial direction Y1 of the pinion shaft 7 and the axial direction Z1 of the rack shaft 8.
According to the present embodiment, the back surface of the rack shaft 8 is covered by the support surface 22a of the rack shaft support member 18, which is a plane parallel to both the axial direction Y1 of the pinion shaft 7 and the axial direction Z1 of the rack shaft 8. By supporting the support portion 8b, the twist (twist) of the rack shaft 8 can be regulated. Therefore, excessive surface pressure does not act on the meshing portion of the rack 8a and the pinion 7a, and durability can be improved.

Further, since there is no response delay when power is transmitted from the pinion shaft 7 to the rack shaft 8 by operating the steering member 2, the driver's steering feeling is good.
Further, since both the supported surface 8b and the support surface 22a are flat, the structure is simple and the manufacturing cost can be reduced.
The displacement of the rack shaft 8 in the direction parallel to the axial direction Y1 of the pinion shaft 7 may be restricted by the rack bush 50 that supports the end of the rack shaft 8.

Next, FIG. 4 shows another embodiment of the present invention. Referring to FIG. 4, this embodiment is different from the embodiment of FIG. 2 as follows. That is, in the embodiment of FIG. 2, the rack shaft support member 18 having a single sliding contact plate 22 is used, but in this embodiment, the rack shaft support member 180 having a pair of sliding contact plates 220 is used. There is in point.
The pair of sliding contact plates 220 constitutes a pair of convex portions that project from the front surface 21 a of the main body 21. The pair of sliding contact plates 220 constituting the pair of convex portions are separated from each other in a direction parallel to the axial direction Y1 of the pinion shaft 7 (vertical direction in FIG. 4). The surface of each sliding contact plate 220 constitutes a support surface 220 a that supports the supported surface 8 b that is the back surface of the rack shaft 7. As shown in FIG. 5, the support surface 220 a of each sliding contact plate 220 is a plane parallel to both the axial direction Y <b> 1 of the pinion shaft 7 and the axial direction Z <b> 1 of the rack shaft 8. Specifically, the protrusion 30 of each sliding contact plate 220 is formed of a protrusion extending in parallel with the axial direction Z1 of the rack shaft 8 and is fitted to a recess provided on the front surface 21a of the rack shaft support member 21. Has been. In the components of the present embodiment, the same components as those of the embodiment of FIG. 2 are denoted by the same reference numerals as those of the embodiment of FIG.

  Also in this embodiment, the same operational effects as the embodiment of FIG. 2 can be obtained. That is, the rear surface of the rack shaft 8 is supported by the support surfaces 220a of the pair of sliding contact plates 220 of the rack shaft support device 180, which are formed of planes parallel to both the axial direction Y1 of the pinion shaft 7 and the axial direction Z1 of the rack shaft 8. By supporting the supported portion 8b, the twist (twist) of the rack shaft 8 can be regulated. Therefore, excessive surface pressure does not act on the meshing portion of the rack 8a and the pinion 7a, and durability can be improved.

Further, since there is no response delay when power is transmitted from the pinion shaft 7 to the rack shaft 8 by operating the steering member 2, the driver's steering feeling is good.
Further, since both the supported surface 8b and the support surface 220a are flat, the structure is simple and the manufacturing cost can be reduced.
The present invention is not limited to the above-described embodiments. For example, in each of the above-described embodiments, the sliding contact plates 22 and 220 are fixed to the corresponding rack shaft support members 18 and 180. You may make it fix to. In addition, various modifications can be made within the scope of the claims of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Vehicle steering device, 2 ... Steering member, 7 ... Pinion shaft, 7a ... Pinion, 8 ... Rack shaft, 8a ... Rack, 8b ... Supported surface, 15 ... Rack shaft support device, 16 ... Holding hole, 17 ... Housing, 18, 180 ... rack shaft support member, 19 ... sealing screw, 20 ... biasing member, 21 ... main body, 21a ... front surface, 22 ... sliding contact plate, 22a ... support surface, 220 ... sliding contact plate (convex portion) ), 220a ... support surface (surface of convex part), X1 ... depth direction of (holding hole), Y1 ... axial direction of pinion shaft,
Z1 ... Axial direction of rack axis

Claims (4)

In a rack shaft support device that supports a rack shaft that meshes with a pinion shaft,
A rack shaft support member held in a holding hole provided in the housing so as to be capable of moving back and forth in the depth direction of the holding hole;
A biasing member housed in the housing and biasing the rack shaft support member toward the rack shaft,
The supported surface provided on the back surface of the rack of the rack shaft is supported by the support surface provided on the rack shaft support member so as to be movable in the axial direction of the rack shaft,
The rack shaft support device, wherein at least one of the supported surface and the support surface is a plane parallel to both the axial direction of the pinion shaft and the axial direction of the rack shaft.   2. The support surface and the support surface according to claim 1, wherein one of the supported surface and the support surface is made up of tops of at least two convex portions separated from each other in a direction parallel to the axial direction of the pinion shaft, and the other is the axial direction of the pinion shaft A rack shaft support device comprising a plane parallel to both axial directions of a shaft.   3. The rack shaft support device according to claim 1, wherein the support surface is constituted by a surface of a low friction sliding contact plate provided on the rack shaft support member.   A vehicle steering apparatus, wherein the rack shaft is slidably supported in the axial direction by using the rack shaft support device according to any one of claims 1 to 3.

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