JP3533281B2 - Rack and pinion steering system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a rack support structure in a rack and pinion type steering device.

[0002]

2. Description of the Related Art A rack and pinion type steering apparatus 101 shown in FIG. 4 covers a part of a rack 103 which meshes with a pinion 102 which is rotated by steering with a housing 104, and a holding hole 105 provided in the housing 104.
The front end side (right side in the figure) of the rack supporting member 106 inserted into the rack is pressed against the back surface of the rack 103 by the spring 107. At a position facing the rear end side of the rack supporting member 106, the opening of the holding hole 105 is inserted into the plug 10.
Closed by 8. Further, a part of the rack 103 protruding from the housing 104 is covered with a tubular covering member (not shown), and the covering member is press-fitted into the housing 104.

The inner peripheral surface of the holding hole 105 and the outer peripheral surface of the rack supporting member 106 are along a cylindrical surface, and the inner peripheral surface of the holding hole 105 guides the rack supporting member 106 back and forth. As the rack support member 106 moves back and forth, the rack 103 bends and the pinion 102 and the rack 1 move.
The meshing error with No. 03 is absorbed, and the meshing is smoothed. Further, the meshing is ensured by restricting the excessive rearward movement distance of the rack support member 106 by the plug 108.

[0004]

The rack supporting member 1 is provided.
When 06 is largely moved in the front-rear direction relative to the pinion 102, the collision noise between the teeth of the rack 103 and the teeth of the pinion 102 becomes large, or the followability of the movement of the rack 103 with respect to the rotation of the pinion 102 decreases, and the steering feel is reduced. Ring drops. Therefore, the gap in the front-rear orthogonal direction between the inner peripheral surface of the holding hole 105 and the outer peripheral surface of the rack supporting member 106 is made as small as possible.

However, when the cover member that covers a part of the rack 103 protruding from the housing 104 is press-fitted into the housing 104, the holding hole 105 is distorted. Therefore, it is difficult to manage the gap size between the inner peripheral surface of the holding hole 105 and the outer peripheral surface of the rack supporting member 106 so as to have a predetermined accuracy.

Further, by making the coefficient of thermal expansion of the material of the rack support member 106 smaller than the coefficient of thermal expansion of the material of the housing 104, the inner peripheral surface of the holding hole 105 and the outer peripheral surface of the rack support member 106. It is necessary to secure a gap between and.

However, if the coefficient of thermal expansion is regulated in this way, the choice of materials will be limited. Therefore, for example, the rack support member is made of a synthetic resin having a relatively large coefficient of thermal expansion in order to reduce the weight, and the housing is made of a metal having a relatively small coefficient of thermal expansion in order to secure the strength.

Further, the rack support member is composed of a pair of divided pieces, and each divided piece is pressed against the inner peripheral surface of the holding hole by a spring, whereby the rack support member is displaced in the front-rear direction relative to the pinion. It is proposed to regulate. However, even in this case, if the holding hole is distorted, the rack support member cannot be smoothly moved back and forth. Also,
In this case, the number of parts is increased and the assembly becomes complicated.

An object of the present invention is to provide a rack and pinion type steering device which can solve the above problems.

[0010]

SUMMARY OF THE INVENTION A rack and pinion type steering device of the present invention includes a pinion which is rotated by steering, a rack which meshes with the pinion, a housing which covers a part of the rack, and the housing which communicates with the rack. A holding hole provided in such a manner, a rack supporting member inserted into the holding hole, an elastic body for pressing the front end side of the rack supporting member against the back surface of the rack, and a position facing the rear end side of the rack supporting member. In a rack and pinion type steering device including a closing member that closes the opening of the holding hole and a covering member that covers the rack portion protruding from the housing and is press-fitted into the housing, a guide hole is provided in the rack supporting member. The guide part that is provided so as to open on the rear end side and that is fitted into the guide hole The gap between the inner peripheral surface of the guide hole and the outer peripheral surface of the guide portion in the front-rear orthogonal direction is an orthogonal front-rear direction between the inner peripheral surface of the holding hole and the outer peripheral surface of the rack support member. It is smaller than the direction of the gap, the elastic
The body is located at the outer side in the radial direction of the inner peripheral surface of the guide hole.
It surrounds the outer peripheral surface of the guide part and the front side of the rack support member.
Elasticity is generated by being compressed between the closing member
It is characterized by being a compression coil spring .

According to the structure of the present invention, the gap between the inner peripheral surface of the guide hole and the outer peripheral surface of the guide portion in the front-rear orthogonal direction is reduced, so that the rack support member extends in the front-rear orthogonal direction with respect to the pinion. The rack support member can be guided back and forth without increasing the amount of movement. Moreover, even if the holding hole is distorted by press-fitting the covering member into the housing, the guide hole is provided in the rack supporting member and the guide portion is provided in the closing member, so that the size of the gap is affected. The predetermined accuracy can be maintained without Accordingly, the rack support member can be smoothly moved back and forth, and it is possible to prevent the collision sound between the rack teeth and the pinion teeth from increasing and the followability of the rack movement with respect to the rotation of the pinion from decreasing. .

Further, by increasing the gap between the inner peripheral surface of the holding hole and the outer peripheral surface of the rack supporting member in the front-rear orthogonal direction, the coefficient of thermal expansion of the material of the rack supporting member and the material of the guide portion is increased. The coefficient of thermal expansion of the material of the housing can be made larger, and the range of material selection can be widened to improve the device.

The inner peripheral surface of the holding hole, the outer peripheral surface of the rack support member, the inner peripheral surface of the guide hole, and the outer peripheral surface of the guide portion are formed along a concentric cylindrical surface. It is preferable that the guide portion can be fitted in the guide hole by screwing the closing member to the. As a result, the assembly can be simplified.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

The rack and pinion type steering device 1 shown in FIGS. 1 and 2 has an input shaft 2 connected to a steering wheel (not shown), a helical pinion 3 provided on the outer periphery of the input shaft 2, and the pinion 3.
A helical rack 4 having teeth that mesh with the teeth of the front side (on the right side in FIG. 1) and a housing 5 that covers a part of the rack 4 are provided. , 7 are supported. A cylindrical screw member 10 is screwed between the input shaft 2 and the housing 5, and the screw member 10 prevents the input shaft 2 and the bearings 6 and 7 from moving in the axial direction. An oil seal 9 is provided between By rotating the pinion 3 by the operation of the steering wheel, the rack 4 moves in the left-right direction of the vehicle, whereby steering wheels connected to both ends of the rack 4 via knuckle arms or the like are steered. In addition, the direction perpendicular to the axis of the rack 4 and
The direction from the rack 4 to the pinion 3 is the front direction.

As shown in FIG. 2, the rack 4 projects from the left end side and the right end side of the housing 5, and the portion projecting from the right end side is covered with a tube (covering member) 8. The right end side of the housing 5 is a cylindrical portion 5a,
The tube 8 is pressed into the inner circumference of the cylindrical portion 5a.

The housing 5 is provided with a holding hole 15 which is open at the rear end side so as to communicate with the rack 4. The inner peripheral surface 15a of the holding hole 15 is formed along the cylindrical surface.

A support yoke (rack support member) 16 is inserted into the holding hole 15 so as to be movable back and forth. The front end side of the support yoke 16 is a supporting surface 16 'which is recessed according to the curvature of the back surface of the rack 4, and the supporting surface 16' supports the rack 4 via the seat 17. A guide hole 31 is provided in the support yoke 16 so as to open on the rear end side.

At a position facing the rear end side of the support yoke 16, a plug (closing member) 18 screwed into the rear end inner circumference of the holding hole 15 closes the rear end side opening 15 'of the holding hole 15. To be done. On the front end side of this plug 18,
A guide portion 32 protruding forward is integrally formed. The outer peripheral surface 32a of the guide portion 32, the inner peripheral surface 15a of the holding hole 15, the outer peripheral surface 16a of the support yoke 16, and the inner peripheral surface 31a of the guide hole 31 are formed along a concentric cylindrical surface. It As a result, the plug 1 is inserted in the holding hole 15.
By screwing 8 together, the guide portion 32 can be fitted in the guide hole 31 so as to be movable in the front-rear direction.
In addition, the tool insertion recess 18 is provided on the rear end side of the plug 18.
a is formed, and a lock nut 19 is screwed onto the outer periphery thereof.

As shown in FIG. 3, a gap δ1 in the front-rear orthogonal direction is formed between the inner peripheral surface 31a of the guide hole 31 and the outer peripheral surface 32a of the guide portion 32, and the inner peripheral surface 15a of the holding hole 15 is formed. And a peripheral surface 16a of the support yoke 16 are formed with a gap δ2 in the front-rear orthogonal direction, and the former gap δ1 is made smaller than the latter gap δ2. For example, the former gap δ1 is about several tens of μm, and the latter gap is about several hundreds μm.

A compression coil spring (elastic body) 20 is inserted into the holding hole 15, and the spring 20 is used as the support yoke 1.
The front end side of the support yoke 16 is pressed against the rear surface of the rack 4 by the elastic force generated by being compressed by being sandwiched between 6 and the plug 18. As a result, backlash between the rack 4 and the pinion 3 is eliminated, and bending of the rack 4 and a meshing error between the pinion 3 and the rack 4 are absorbed by the back and forth movement of the support yoke 16 to facilitate the meshing. I am trying. In addition, the rearward movement distance of the support yoke 16 is set to the front end surface 32 of the guide portion 32.
b and the set dimension S between the front and rear of the bottom surface 31b of the guide hole 31
By regulating the inside, the meshing of the pinion 3 and the rack 4 is secured.

According to the above structure, the inner peripheral surface 31a of the guide hole 31 of the support yoke 16 and the outer peripheral surface 3 of the guide portion 32 are formed.
By reducing the gap δ1 in the front-rear orthogonal direction with 2a, the support yoke 16 can be guided back and forth without increasing the amount of movement of the support yoke 16 in the front-rear orthogonal direction with respect to the pinion 3. Moreover, even if the holding hole 15 is distorted by press-fitting the tube 8 into the housing 5, the size of the gap δ1 is not affected and a predetermined accuracy can be maintained. As a result, the support yoke 16 can be smoothly moved back and forth, and the rack 4
It is possible to prevent the collision sound between the tooth of the pinion 3 and the tooth of the pinion 3 from becoming loud and the followability of the movement of the rack 4 with respect to the rotation of the pinion 3 from being deteriorated.

Also, by increasing the gap δ2 in the front-rear orthogonal direction between the inner peripheral surface 15a of the holding hole 15 and the outer peripheral surface 16a of the support yoke 16, the support yoke 1 is formed.
The coefficient of thermal expansion of the material of 6 and the material of the guide portion 32 can be made larger than the coefficient of thermal expansion of the material of the housing 5, and the range of material selection can be widened to improve the apparatus. For example,
The support yoke 16 and the plug 18 forming the guide portion 32 are made of hard synthetic resin, and the housing 5 is made of aluminum die cast, so that the weight can be reduced while maintaining the strength.

Further, by simply screwing the plug 18 into the holding hole 15, the guide portion 32 can be fitted into the guide hole 31, and the assembling process can be simplified.

The present invention is not limited to the above embodiment. For example, the rack and pinion type steering device to which the present invention is applied is not limited to the manual type, and may be the power steering type.

[0026]

According to the rack and pinion type steering device of the present invention, it is possible to prevent the collision noise between the rack teeth and the pinion teeth from increasing and the followability of the movement of the rack with respect to the rotation of the pinion from decreasing. Further, the range of material selection can be widened to improve the device, and the assembly can be simplified.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of a rack and pinion type steering device according to an embodiment of the present invention.

FIG. 2 is a rear partial cross-sectional view of an essential part of the rack and pinion steering device according to the embodiment of the present invention.

FIG. 3 is a sectional view taken along the line III-III in FIG.

FIG. 4 is a partial sectional view of a conventional rack and pinion type steering device.

[Explanation of symbols]

3 pinion 4 racks 5 housing 8 tube (covering member) 15 retaining hole 16 Support yoke (rack support member) 18 plug (closing member) 20 spring (elastic body) 31 Guide hole 32 Guide

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B62D 3/00-3/12

Claims (3)

(57) [Claims] 1. A pinion that rotates by steering, a rack that meshes with the pinion, a housing that covers a part of the rack, a holding hole that is provided in the housing so as to communicate with the rack, and is inserted into the holding hole. A rack support member, an elastic body that presses the front end side of the rack support member against the back surface of the rack, and a closing member that closes the opening of the holding hole at a position facing the rear end side of the rack support member, While covering the rack part protruding from the housing,
In a rack and pinion type steering device including a cover member press-fitted into the housing, a guide hole is provided in the rack support member so as to open at a rear end side, and a guide portion fitted into the guide hole is closed. The gap in the front-rear orthogonal direction between the inner peripheral surface of the guide hole and the outer peripheral surface of the guide portion is the front-rear orthogonality between the inner peripheral surface of the holding hole and the outer peripheral surface of the rack support member. It is smaller than the direction of the gap, the elastic body, our radially outward of the inner circumferential surface of the guide hole
Surrounding the outer peripheral surface of the guide portion and supporting the rack.
Resilient by being compressed by being sandwiched between the member and the closing member
A rack and pinion type steering device that is a compression coil spring that produces 2. The rack and pinion steering apparatus according to claim 1, wherein the material of the rack supporting member and the material of the guide portion have a coefficient of thermal expansion greater than that of the material of the housing. 3. The inner peripheral surface of the holding hole, the outer peripheral surface of the rack support member, the inner peripheral surface of the guide hole, and the outer peripheral surface of the guide portion are formed along a concentric cylindrical surface. The rack and pinion steering device according to claim 1 or 2, wherein the guide portion can be fitted into the guide hole by screwing the closing member into the holding hole.