JPS623337Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a rack-and-pinion steering device for automobiles, etc., and particularly to the structure of its retainer.

Examples of conventional rack-and-pinion steering devices include those shown in FIGS. 1 to 3. That is, 1 shown in FIG. 1 is a steering gear housing, and a rack tube 2 is continuous on one side of a hole that passes through the steering gear housing 1. A rack shaft 3 as shown in the figure is provided. Ball sockets (not shown) are attached to both ends of the rack shaft 3, and ball studs (not shown) of steering rods 4, 4 are fitted into each ball socket, respectively. Both steering rods 4, 4 are connected via ball joints, knuckle arms, etc. (not shown).
Similarly, it is connected to a steering wheel (not shown). 5,5
is a boot that covers the fitting portion of the ball socket and ball stud and the sliding surface of the rack shaft 3.

Further, as shown in FIG. 2, the steering gear housing 1 includes a pinion 6 connected to a steering shaft (not shown), a bearing 7,
8, it is rotatably supported and built-in.
The pinion 6 meshes with a rack 3a of the rack shaft 3 in the steering gear housing 1, and the steering gear housing is provided on the opposite side (back surface) of the rack shaft 3 from the rack 3a so as to be slidable in the axial direction. A retainer 10 is supported by the rack shaft 3 and is urged toward the rack shaft 3 by the spring force of a spring 9.

On the rack shaft 3 side of the retainer 10, a cushioning material 11 made of a synthetic resin material with a small coefficient of friction, etc.
are fixed together by press-fitting the root portion 11a into the hole of the retainer 10, and the arc-shaped concave surface 11b (see FIG. 3) of the cushioning material 11 is in contact with the back surface of the rack shaft 3. . Reference numeral 12 denotes an adjusting screw, and one end of the adjusting screw 12 passes through the end cover 13 and faces the retainer 10, and restricts the backward movement of the retainer 10 to connect the rack 3a and the pinion. Maintain an appropriate backlash between 6 and 6. Note that 14 is a dust seal.

When the steering wheel is rotated and the steering shaft is rotated, the pinion 6 connected to the tip of the steering shaft is rotated in the same direction, and the rack shaft 3 having the rack 3a that meshes with the pinion 6 is rotated to rotate the pinion. 6 in the axial direction corresponding to the direction of rotation. At this time, the rack 3a is attached to the rack shaft 3.
Due to the meshing of the pinion 6 with the pinion 6, a bending moment is generated that acts in a direction away from the pinion 6, but due to the pressing force from the retainer 10, which is in pressure contact with the back surface of the rack shaft 3 via the buffer material 11, the bending caused by the bending moment is is canceled out, and therefore the straightness of the rack shaft 3 is maintained and the rack 3a
The meshing between the pinion 6 and the pinion 6 is ensured. Also,
By adjusting the amount of protrusion of the adjusting screw 12, the backlash between the rack 3a and the pinion 6 can be set appropriately.

However, in the retainer structure of such a conventional rack-and-pinion steering device, what comes into contact with the rack shaft 3 is the cushioning material 1 made of a synthetic resin material with a small coefficient of friction.
1, the retainer 10 does not directly contact the rack shaft 3, but is connected to the retainer 10 through the cushioning material 11.
However, the structure is such that it receives the bending moment acting on the rack shaft 3 caused by the engagement between the pinion 6 and the rack 3a. Therefore, if an excessive bending moment is applied to the rack shaft 3, the cushioning material 11
The surface pressure of the concave surface 11b exceeds its allowable surface pressure, permanent distortion occurs in the cushioning material 11, and the shape of the concave surface 11b is deformed.
1, or the backlash between the rack 3a and the pinion 6 increases.

This invention was made by focusing on such conventional problems, and includes forming a relief part in the direction in which the cushioning material moves away from the rack shaft in the retainer that urges the rack shaft toward the pinion side, and The surface of the retainer on the rack shaft side faces into the hole provided through the cushioning material, and the tip of the retainer does not normally touch the rack shaft, and only acts as a buffer when the input from the rack shaft is large. By providing a structure with a protrusion whose tip touches the rack shaft as the material undergoes elastic deformation, when the bending moment acting on the rack shaft exceeds a certain limit when force is transmitted between the rack and pinion, The purpose of this invention is to directly support the bending moment with a retainer made of a steel material having high rigidity and high surface pressure, thereby solving the above problem.

This invention will be explained below based on the drawings.

4 to 7 are diagrams showing an embodiment of this invention.

First, to explain the structure, reference numeral 1 shown in FIG. 4 is a steering gear housing. This steering gear housing 1 has a hole passing through it, and on one side of this hole there is a rack tube similar to the one shown in FIG. (not shown) are connected to each other, and a rack shaft 3 is inserted through the steering gear housing 1 and the rack tube so as to be movable in the axial direction. Although not particularly shown, ball sockets are attached to both ends of the rack shaft 3, which has a rack 3a in the middle in the axial direction, as in the conventional example shown in FIG. 1, and each ball socket has a steering rod. The ball studs are fitted together, and the steering rod is fitted with a ball joint,
Connects to the steering wheel via a knuckle arm or the like.

The steering gear housing 1 includes a connecting shaft portion 6a in which a serration is formed so that the pinion 6 is connected to a steering shaft (not shown).
The steering gear housing 1 protrudes from the steering gear housing 1, and is rotatably supported by two bearings 7 and 8 and housed therein. The pinion 6 meshes with the rack 3a of the rack shaft 3 within the steering gear housing 1. On the opposite side of the rack shaft 3 from the rack 3a (hereinafter referred to as the "back"), that is, at a position corresponding to the pinion 6 across the rack shaft 3, the rack shaft 3 is supported by the steering gear housing 1 so as to be slidable in the axial direction. Then, the retainer 20 is installed.

As shown in FIGS. 4 and 5, the retainer 20 has a cylindrical shape, and the end on the rack shaft 3 side is formed into a concave arcuate surface 20a. A protrusion 20c having a support surface 20b having a similar arc shape is provided in the central portion, and a hole 20d is provided inside the arc surface 20a.
is provided. Rack shaft 3 of such retainer 20
An arc-shaped cushioning material 21 made of a synthetic resin material with a small friction coefficient is attached to the side end to reduce the sliding frictional resistance between the rack shaft 3 and the rack shaft 3.

The concave surface 21a of the cushioning material 21 has a radius of curvature corresponding to the outer circumferential surface of the rack shaft 3, and the concave surface 21a of the retainer 20 penetrates the upper and lower surfaces in the central portion, and the protrusion 20c of the retainer 20 is fitted therein. The hole 21b further has a root portion 21c with a slightly larger diameter than the hole 20d of the retainer 20 at a position corresponding to the hole 20d of the retainer 20 on the convex side.
are provided for each. Then, the buffer material 21
By press-fitting the root portion 21c into the hole 20d of the retainer 20, the retainer 20 and the buffer material 21 are fixed together. As shown in an enlarged view in FIG. 6, the height of the protrusion 20c of the retainer 20 is hidden within the hole 21b of the buffer material 21 in a normal state in which no excessive bending moment is applied to the rack shaft 3. On the other hand, in a state where an excessive bending moment is applied, the supporting surface 20b of the cushioning material 21 is set to coincide with the concave surface 21a of the cushioning material 21 as the cushioning material 21 is elastically deformed. Therefore, retainer 2
A gap is set in advance inside the arcuate surface 20a of 0 so that the cushioning material 21 can be elastically deformed, and this gap forms a relief part 20f in the direction in which the cushioning material 21 moves away from the rack shaft 3. do. This relief portion 20f is a part of the cushioning material that is formed when the retainer 20 and the rack shaft 3 are displaced in a direction in which they approach each other, and when a surface pressure exceeding the allowable surface pressure is applied to the cushioning material 21 from the rack shaft 3. 21 refers to the part that can escape in the direction away from the rack shaft 3.

The retainer 20 provided with the buffer material 21 is urged toward the rack shaft 3 by a spring 9 whose one end is seated on the end cover 13. The end cover 13 is attached to the steering gear housing 1 by bolts (not shown) or the like.
The adjuster screw 12 is fixed to the center portion thereof, and an adjuster screw 12 passes through the center portion thereof. Asian Screw 1
The tip inserted into the steering gear housing 1 of No. 2 faces the bottom of the hole 20e of the retainer 20 and comes into contact with the presser plate 22 loosely fitted into the hole 20e, thereby preventing the backward movement of the retainer 20. By restricting the backlash between the rack 3a and the pinion 6, the meshing between them is ensured. 23 shown in FIG. 4 is a lock nut.

Next, the action will be explained.

To assemble this steering gear device, first,
A rack tube is attached to one side of the hole in the steering gear housing 1, and then a rack shaft 3 is provided passing through the steering gear housing 1 and the rack tube, and furthermore, ball sockets are attached to both ends of the rack shaft 3. Next, the pinion 6 is inserted into the steering gear housing 1, and the pinion 6 is meshed with the rack 3a of the rack shaft 3, and is rotatably supported by the two bearings 7 and 8.

Next, the retainer 2 with the cushioning material 21 attached in advance
0 into the steering gear housing 1 from the cushioning material 21 side, aligning the concave surface 21a of the cushioning material 21 with the back surface of the rack shaft 3, and sequentially insert the press plate 22 and the spring 9 into the hole 20e of the retainer 20. insert. After that, the end cover 13 to which the adjuster screw 12 has been screwed in advance is attached to the end cover 1.
3 fixes the spring 9 to the steering gear housing 1 in a compressed state. Adjustment of the backlash between the rack 3a and pinion 6 of the steering gear device assembled in this manner is performed by appropriately moving the adjusting screw 12 forward and backward.

When the steering wheel is rotated and the steering shaft is rotated, a pinion 6 connected to the tip thereof rotates in the same direction as the steering wheel, and a rack shaft 3 having a rack 3a meshing with the pinion 6 is rotated. is moved in an axial direction corresponding to the rotational direction of the pinion 6. At this time, as shown in FIG. 6, only the concave surface 21a of the cushioning material 21 contacts the back surface of the rack shaft 3, and the support surface of the tip of the protrusion 20c of the retainer 20 hidden in the hole 21b of the cushioning material 21. 20b does not make contact. Therefore, only the cushioning material 21 having a small coefficient of friction comes into sliding contact with the rack shaft 3, so that smooth relative movement between the two 3 and 21 is ensured.

On the other hand, when a large bending moment is generated on the rack shaft 3 and acts on the cushioning material 21, as in the case where a large external force is input from both ends of the rack shaft 3 during bounce/rebound, the bending moment from the rack shaft 3 is Due to the pressing force, the cushioning material 21 bulges outward due to elastic deformation, as shown in FIG. The material 21 escapes into the relief portion 20f, and the support surface 20b of the retainer 20 comes into contact with the back surface of the rack shaft 3. Therefore, the bending moment becomes
The bending moment acts on both the retainer 20 and the buffer material 21, but since the retainer 20 is a rigid body and the buffer material 21 is an elastic body, all bending moments exceeding a certain limit act on the retainer 20. Therefore, since the surface pressure acting on the cushioning material 21 does not exceed its permissible surface pressure, the shape of the concave surface 21a of the cushioning material 21 will not be deformed due to permanent deformation. Therefore, the frictional resistance between the rack shaft 3 and the buffer material 21 does not increase, and furthermore, an increase in backlash between the rack 3a and the pinion 6 can be suppressed.

When the excessive bending moment disappears, the deformation of the buffer material 21 is within the elastic limit, so the buffer material 21 returns to its original shape. Therefore, the protrusion 20c of the retainer 20 is again inserted into the hole 2 of the buffer material 21.
1b with relative displacement. Therefore,
Thereafter, as in the initial state, only the concave surface 21a of the cushioning material 21 comes into contact with the back surface of the rack shaft 3, so that smooth relative movement between the rack shaft 3 and the cushioning material 21 is ensured.

As explained above, in this invention, a relief part is formed in the retainer that biases the rack shaft toward the pinion side in the direction in which the buffer material moves away from the rack shaft, and a relief part is formed on the surface of the retainer on the rack shaft side. ,
It faces into the hole made through the cushioning material, and normally its tip does not touch the rack shaft, and only when the input from the rack shaft is large, the elastic deformation of the cushioning material causes its tip to touch the rack shaft. The structure has a protrusion that the tips touch. For this reason, normally the retainer supports the rack shaft via a cushioning material made of a synthetic resin material with a small coefficient of friction and high elasticity, and an excessive bending moment is applied to the rack shaft and this buffers the shaft. When acting on the material side, the cushioning material is pushed by the rack shaft and escapes into the relief part, and the rack shaft can be directly supported by the highly rigid retainer. Therefore, since the surface pressure acting on the cushioning material does not exceed its allowable surface pressure, the shape of the concave surface of the cushioning material is not deformed due to permanent deformation, and an increase in the coefficient of friction is prevented. Therefore, smooth relative movement between the rack shaft 3 and the buffer material 21 can be ensured, and an increase in backlash between the rack and pinion can be suppressed. It will be done.

[Brief explanation of the drawing]

Figures 1 to 3 show the conventional rack and
This shows a pinion type steering device, and the first
The figure is an overall view, Figure 2 is a cross-sectional view taken along the - line in Figure 1,
FIG. 3 is a bottom view of the retainer, FIGS. 4 to 7 are views showing an embodiment of this invention, and FIG. 4 is a sectional view of a portion corresponding to the - line cross section in FIG.
Fig. 5 is a bottom view of the retainer, Fig. 6 is an enlarged sectional view of main parts showing the relationship between the rack shaft and the retainer in a normal state, and Fig. 7 is a diagram showing the rack shaft in a state where an excessive bending moment is applied to the rack shaft. FIG. 3 is an enlarged cross-sectional view of main parts showing the relationship with the retainer. 1...Steering gear housing, 3...Rack shaft, 3a...Rack, 6...Pinion, 9...
...Spring, 12...Adjust Screw,
13...End cover, 20...Retainer, 20a...Circular surface, 20b...Support surface, 20c...Protrusion, 20
d...hole, 20e...hole, 20f...relief, 2
1... Cushioning material, 21a... Concave surface, 21b... Hole,
21c...root.

Claims (1)

[Scope of utility model registration request] A pinion connected to the steering shaft,
a steering gear housing with a built-in pinion; a rack shaft passing through the steering gear housing and having a rack that meshes with the pinion within the steering gear housing; In the rack-and-pinion steering device, the retainer is provided with a relief part in a direction in which the buffer material moves away from the rack shaft, and the retainer is provided with a relief part on the rack shaft side. The surface faces the hole made through the cushioning material, and normally its tip does not touch the rack shaft, and only when the input from the rack shaft is large, the elastic deformation of the cushioning material occurs. A rack and pinion type steering device characterized in that a protrusion is provided on the rack shaft, the tip of which touches the protrusion.