JPH10338148A - Rack and pinion type steering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure return of a steering wheel into a straight advancing steering position and to facilitate maintenance and inspection without impeding the mesh of a rack and a pinion. SOLUTION: A rack and pinion type steering system is provided with a housing 5 fixed to a vehicle body so as to cover a rack 4 meshed with a pinion rotated by the operation of a steering wheel. The rack 4 is moved in relation to the vehicle body by the rotation of the pinion according to a steering angle. Elastic bodies 20a, 20b elastically deformed by the movement of the rack 4 in relation to the vehicle body at the time of the steering angle being the set value or more are arranged in positions away from the housing 5 in an orthogonal direction to the longitudinal direction of the rack 4. Restoring force for putting the rack 4 back into a straight advancing steering position is imparted by the elastic deformation of the elastic bodies 20a, 20b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rack and pinion type steering device having a function of returning a steering wheel to a straight steering position.

[0002]

2. Description of the Related Art A pinion that rotates by operating a steering wheel, a rack that meshes with the pinion, and a housing that is fixed to a vehicle body so as to cover the rack are provided. Conventionally, a rack and pinion type steering device which is moved relative to a vehicle body has been widely used.

Generally, a force that returns a steering wheel after steering to a straight-ahead steering position is exerted by the wheel alignment of the vehicle. However, in the rack-and-pinion type steering device, when the steering angle increases, the steering wheel may not be able to return to the straight steering position smoothly due to friction of the support portion of the rack.

Therefore, when the steering angle is equal to or larger than a set value,
There is a conventional example in which a pair of springs elastically deformed by the movement of the rack with respect to the vehicle body is provided, and a restoring force for returning the rack to the straight steering position is provided by the elastic deformation of each spring.

[0005]

In the prior art, each spring was fitted on the outer periphery of the rack inside the housing covering the rack. Therefore, there is a possibility that the spring is broken and the spring is engaged in the engagement portion between the rack and the pinion inside the housing. Also, since each spring is inside the housing, assembly is troublesome and maintenance and inspection cannot be performed easily.

When the steering assisting force is applied based on the hydraulic pressure, if the outer periphery of the rack is damaged by a spring, oil may leak from between the outer periphery of the rack and the oil seal.

[0007] Further, the longitudinal dimension of the rack of the steering device becomes large, and it is not possible to share parts with the steering device without such a spring. Furthermore, since the spring that provides elasticity during right steering is disposed at one end of the rack, and the spring that provides elasticity during left steering is disposed at the other end of the rack, the springs must be assembled from different directions. , Assembly and maintenance was more troublesome.

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

[0009]

SUMMARY OF THE INVENTION The present invention comprises a pinion that rotates by operating a steering wheel, a rack that meshes with the pinion, and a housing that is fixed to a vehicle body so as to cover the rack, and the rotation of the pinion is provided. Accordingly, the rack is moved with respect to the vehicle body in accordance with the steering angle, and when the steering angle is equal to or larger than the set value, an elastic body that is elastically deformed by the movement of the rack with respect to the vehicle body is provided. Thus, the present invention is applied to a rack and pinion type steering device in which a restoring force for returning the rack to the straight steering position is applied. A feature of the rack and pinion type steering device of the present invention resides in that the elastic body is disposed at a position away from the housing in a direction orthogonal to the longitudinal direction of the rack. According to the configuration of the present invention, since the elastic body is located outside the housing, even if the elastic body is damaged, the elastic body does not reach the meshing portion between the rack and the pinion, and assembly and maintenance and inspection of the elastic body can be easily performed. In addition, since the longitudinal dimension of the rack of the steering device does not change, parts can be shared with a steering device without such an elastic body.

[0010] A holding member is provided so as to be able to move along with the rack, and a first compression coil spring and a second compression coil spring arranged in parallel along the moving direction of the rack as the elastic body are provided on the outer periphery of the holding member. , Are fitted so as to be relatively displaceable in the moving direction of the rack,
A spring receiver and a third spring receiver between the first spring receiver and the second spring receiver are arranged in parallel along the moving direction of the rack, and the first spring receiver and the second spring receiver are connected to the rack. The third spring receiver is fixed to one of the two sides of the vehicle body, and the third spring receiver is fixed to one of the other sides of the rack and the vehicle body. The first compression coil spring is disposed between the first spring receiver and the third spring receiver so that the second compression coil spring is compressed when the steering angle to the other of the left and right sides is equal to or greater than a set value. A second compression coil spring is disposed between the second spring receiver and the third spring receiver, and the natural length of each compression coil spring is
It is preferable that the interval between the spring supports for receiving the respective compression coil springs is shorter than the interval between the spring receivers. Thereby, the first compression coil spring and the second compression coil spring can be arranged close to each other, and assembly and maintenance and inspection can be facilitated. In addition, since the natural length of each compression coil spring is shorter than the interval between the spring receivers that receive each compression coil spring, it is not necessary to apply a force to elastically deform each compression coil spring when assembling. Further, each compression coil spring can be relatively displaced with respect to the holding member, and need only be fitted to the holding member. Thereby, assembly can be simplified.

[0011] The rack and pinion type steering apparatus of the present invention includes a piston provided on the outer periphery of the rack,
It is preferable that a pair of oil chambers partitioned by a piston is formed inside the housing, and a steering assist force is applied based on a hydraulic pressure acting on the piston. In this case, since the outer periphery of the rack is not damaged by the spring, oil leakage from the oil chamber can be prevented.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

A rack and pinion type hydraulic power steering device 1 shown in FIGS. 1 and 2 includes a steering shaft 2 connected to a steering wheel (not shown).
And a pinion 3 provided on the steering shaft 2 so as to rotate by operating the steering wheel.
And a rack 4 having teeth 4a meshing with the pinion 3.
And a housing 5 fixed to the vehicle body so as to cover the pinion 3 and the rack 4. Tie rods 7a, 7b are attached via ball joints 6a, 6b to each end of the rack 4 protruding from an end opening of the housing 5, and wheels are connected to the tie rods 7a, 7b via knuckle arms or the like. . Due to the rotation of the pinion 3 due to the steering, the rack 4 moves in the longitudinal direction with respect to the vehicle body in accordance with the steering angle, and the vehicle is steered. The rack 4
Is a bush 8 built in one end of the housing 5.
And a support yoke (not shown) built in the housing 5 at a position where the pinion 3 is engaged. The housing 5 and the ball joint 6a,
In order to prevent muddy water, dust and the like from entering the 6b, a tubular elastic cover 9 is attached.

A piston 10 is provided on the outer periphery of the rack 4 and a pair of oil chambers 1 partitioned by the piston 10 are provided.
1 a and 11 b are formed inside the housing 5.
One end of the oil chamber 11a is sealed by an oil seal 12a between the outer circumference of the rack 4 and the inner circumference of the housing 5, and the other end of the oil chamber 11b is connected to the outer circumference of the bush 8 and the housing 5. O-ring 12b between the inner circumference and oil seal 12c between the inner circumference of the bush 8 and the outer circumference of the rack
Sealed by One end of each of pipes 14 and 15 for supplying pressure oil to each of the oil chambers 11 a and 11 b is connected to the housing 5, and the other end of each of the pipes 14 and 15 is a control valve provided around the steering shaft 2. 1
6 is connected. The control valve 16
According to the steering resistance and the steering direction, one of the two oil chambers 11a and 11b is supplied with high-pressure oil supplied by a pump from a tank (not shown), and the oil is returned to the tank from the other. be able to. This allows
The steering assist force can be applied based on the hydraulic pressure acting on the piston 10.

When the steering angle is equal to or greater than a set value, the first compression coil spring 20a and the second compression coil spring are arranged in parallel along the moving direction of the rack 4 as elastic bodies which are elastically deformed by the movement of the rack 4 with respect to the vehicle body. 20b are provided.

That is, the connecting member 21 is fitted around the outer periphery of one end of the rack 4, and the connecting member 21 is prevented from falling off by the ball joint 6 a screwed into one end of the rack 4. The connecting member 21 includes a first spring receiver 2 extending from the rack 4 in a direction orthogonal to the longitudinal direction of the rack.
A male screw 22a on one end of a cylindrical holding member 22 is screwed into a female screw 21a 'formed in the first spring receiver 21a. Thereby, the holding member 22 can be moved along with the rack 4. The axial direction of the holding member 22 is along the longitudinal direction of the rack 4, and the other end of the holding member 22 is closer to the other end of the rack 4 than one end. The two compression coil springs 20
a and 20b are fitted so as to be relatively displaceable in the moving direction of the rack 4. Thereby, each compression coil spring 20a, 2
Ob is disposed at a position away from the housing 5 in a direction orthogonal to the longitudinal direction of the rack 4.

The male screw 22 on the outer periphery of the other end of the holding member 22
The internal thread 23a on the inner periphery of the annular second spring receiver 23 is screwed to b. Between the first spring receiver 21a and the second spring receiver 23, an annular third spring receiver 24 is fitted to the outer periphery of the holding member 22 so as to be relatively movable along the longitudinal direction of the rack 4. The third spring receiver 24 is
It is fixed to the housing 5 fixed to the vehicle body via the arm 24a. Note that the third spring receiver 24 may be directly fixed to the vehicle body. Thereby, each spring receiver 21a, 23,
24 are arranged along the moving direction of the rack 4,
The spring receiver 21a and the second spring receiver 23 are fixed to the rack 4 side, and the third spring receiver 24 is fixed to the vehicle body side.

The natural length L of the first compression coil spring 20a
1 is shorter than the distance D1 between the first spring receiver 21a and the third spring receiver 24, and the difference D1-L1 is such that the first compression coil spring 20a is compressed when the left or right steering angle is equal to or larger than a set value. Is set to The natural length L2 of the second compression coil spring 20b is shorter than the distance D2 between the second spring receiver 23 and the third spring receiver 24, and the difference D2-L2
Is set such that the second compression coil spring 20b is compressed when the steering angle to the left and right sides is equal to or greater than a set value.
The natural lengths L1 and L2 of the springs are equal to each other, and the spring receiving intervals D1 and D2 are equal to each other. In FIG. 2, the positions of the first spring receiver 21a and the second spring receiver 23 when the steering is performed to the steering limit are indicated by a two-dot chain line. The setting value of the steering angle is
It is appropriately determined so that the steering wheel can be smoothly returned to the straight steering position. Thereby, the first compression coil spring 20a is elastically deformed when steering left or right, and the second compression coil spring 20a when steering left or right.
Due to the elastic deformation of b, a restoring force for returning the rack 4 to the straight steering position is applied.

According to the above configuration, each compression coil spring 20
By applying a restoring force for returning the rack 4 to the straight-ahead steering position by using a and 20b, it is possible to prevent the steering wheel from being hindered from returning to the straight-ahead steering position. Since each of the compression coil springs 20a and 20b is located outside the housing 5, even if the compression coil springs 20a and 20b are damaged, they do not reach the engagement portion between the rack 4 and the pinion 3a, and the assembly and maintenance and inspection of the compression coil springs 20a and 20b can be easily performed. . In addition, since the longitudinal dimension of the rack of the steering device 1 does not change, parts can be shared with a steering device without such compression coil springs 20a and 20b. The first compression coil spring 20a and the second compression coil spring 2
0b can be arranged close to each other, facilitating assembly and maintenance. Natural length L of each compression coil spring 20a, 20b
1, L2 is shorter than the distances D1, D2 between the spring receivers 21a, 23, 24 for receiving the respective compression coil springs 20a, 20b.
There is no need to apply a force to elastically deform Ob. In addition, each of the compression coil springs 20a and 20b can be relatively displaced with respect to the holding member 22, and only needs to be fitted to the holding member 22. Thereby, assembly can be simplified. Further, the outer circumference of the rack 4 is formed by the compression coil springs 20a, 20b.
There is no gap between the rack 4 and the oil seal 12c because the oil chamber 1 is not damaged.
1b can be prevented from leaking.

The present invention is not limited to the above embodiment. For example, the first spring receiver 21a and the second spring receiver 23 may be fixed to the vehicle body side, and the third spring receiver 24 may be fixed to the rack 4 side.

[0021]

According to the present invention, the return of the steering wheel to the straight steering position can be ensured, the engagement between the rack and the pinion is not disturbed, the maintenance and inspection can be easily performed, and the steering assist force is provided by hydraulic pressure. Can provide a rack-and-pinion type steering device that can prevent oil from leaking when imparting.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a steering device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the steering device according to the embodiment of the present invention.

[Explanation of symbols]

 3a Pinion 4 Rack 5 Housing 10 Piston 11a, 11b Oil chamber 20a First compression coil spring 20b Second compression coil spring 21a First spring receiver 23 Second spring receiver 24 Third spring receiver

Claims (3)

[Claims] A pinion that rotates by operating a steering wheel; a rack that meshes with the pinion; and a housing that is fixed to a vehicle body so as to cover the rack. The rotation of the pinion causes the rack to reach a steering angle. When the steering angle is equal to or larger than a set value, an elastic body is provided which is elastically deformed by the movement of the rack with respect to the vehicle body. A rack and pinion type steering device in which a restoring force is applied to the rack and pinion, wherein the elastic body is arranged at a position away from the housing in a direction orthogonal to a longitudinal direction of the rack. A first compression coil spring and a second compression coil spring which are arranged along the moving direction of the rack as the elastic body;
A first spring receiver, a second spring receiver, and a third spring receiver between the first spring receiver and the second spring receiver are fitted around the outer periphery of the holding member so as to be relatively displaceable in the moving direction of the rack. Are arranged along the moving direction of the rack, the first spring receiver and the second spring receiver are fixed to one of the rack and the vehicle body, and the third spring receiver is mounted on the rack and the vehicle body. Is fixed to one of the other side, and the first compression coil spring is compressed between the first spring receiver and the third spring receiver so that the first compression coil spring is compressed when the left or right steering angle is equal to or greater than a set value. A second coil spring is disposed between the second spring receiver and the third spring receiver so that the second compression coil spring is compressed when the steering angle to the left and right sides is equal to or greater than a set value.
The rack and pinion type steering device according to claim 2, wherein a compression coil spring is arranged, and a natural length of each compression coil spring is shorter than an interval between spring supports for receiving each compression coil spring. 3. A piston provided on an outer periphery of the rack, a pair of oil chambers partitioned by the piston is formed inside the housing, and a steering assist force is applied based on a hydraulic pressure acting on the piston. 3. The rack and pinion type steering device according to 2.