JPH0410151Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a rear wheel steering device for a four-wheel steering vehicle.

BACKGROUND ART Vehicles are known in which not only the front wheels but also the rear wheels are steered in order to improve the steering performance of the vehicle. An example of this is shown in the system diagram shown in Fig. 2 and the link shown in Fig. 2A. This will be explained using an enlarged view of the mounting part. In the figure, 1 is the steering wheel, 2
is a power cylinder, and the inside of this power cylinder 2 is divided into a working chamber 4 and a working chamber 5 by a piston 3.
It is separated into A shaft 6 is connected to the piston 3 and moves left and right as the steering wheel 1 is rotated. Reference numeral 7 indicates a PS system hydraulic circuit, in which hydraulic oil obtained by a pump 8 is supplied to and discharged from the working chambers 4 and 5 of the power cylinder 2 via pipes 9 and 10 by the action of a control valve J. ing. Therefore, when the steering wheel 1 is rotated, the assisting force of the piston 3 is applied by the PS system hydraulic circuit 7 to rotate the front wheels 12, 12.
The steering becomes easier.

On the other hand, an outline of the configuration of the rear wheel steering device is as follows. That is, the elastic body 1 is placed between the inner ring 14 and the outer ring 15.
6 is filled to form a cylindrical bushing 17, and the cylindrical bushings 17 are fixed at both ends to form a pair of links 18 and 19. One of the links 19 is formed into a substantially U-shape with a recess 19a in the center. On the other hand, the suspension member 20 and the axle member 21 are provided with central shafts 23 and 24, respectively, which extend in the longitudinal direction of the vehicle and pass through these members 20 and 21 in a direction perpendicular to the axle 22. Each cylindrical bush 17...17 of each link 18, 19 is provided at both ends of the link 18, 19.
is inserted, and the pair of links 18 and 19 are arranged substantially parallel to each other. These pair of links 1
A power cylinder 25 is disposed near one of the links 19 of 8 and 19 in a state where interference with the link 19 is avoided by a recess 19a formed in the power cylinder 25, and its cylinder body 26 is inserted into the cylindrical bush 17. It is connected to the central shaft 23 on the suspension member side via. Further, a piston 27 is connected to the central shaft 24 on the axle member side via the cylindrical bush 17 provided at the tip of a piston rod 27a integrally provided therewith. A rear wheel control hydraulic circuit 33 is constructed by connecting the working chambers 28 and 29 of the power cylinder 25 to the circulation pipes 31 and 32 of the pump 30. Each working chamber 28, 28, 29, 2 of this power cylinder 25, 25
9 is connected to pipe 3 by the action of control valve K.
By supplying and discharging hydraulic oil through the bushings 1 and 32, the cylindrical bushes 17 and 17 are deflected, and the central shafts 23 and 23 on the axle side are rotated according to the amount of deformation, and the rear wheels are rotated. 34, 34 are being steered as shown by arrow B. Reference numeral 35 designates a vehicle speed sensor, and the open/close state of the variable throttle valve 37 is controlled by an electronic controller 36 which receives a signal from the vehicle speed sensor 35 and issues a control signal. Therefore, the steering angles of the rear wheels 34, 34 are configured to change depending on the vehicle speed.

Problems to be Solved by the Invention However, in the rear wheel steering device of such a conventional four-wheel steering vehicle, the power cylinder 25 for rear wheel steering is disposed approximately in the middle of one link 19. However, there were problems in that the rigidity of the link 19 decreased and the structure became complicated. That is, in order to set the links 18 and 19 substantially parallel to the axle direction and to arrange the power cylinder 25 on one link 19 side without interfering with this link 19, the link 1 is set as shown in the figure.
9 is bent into a substantially U-shape to form a recess 19a, and the power cylinder 25 is disposed within the recess 19a that connects both ends of the link 19. This makes the structure complicated, and the power cylinder Since the operating force of 25 acts in the direction of bending the U-shaped link 19, the link 19 bends during operation, resulting in a problem of reduced rigidity.

Therefore, the present invention solves the problems of the rear wheel steering device in conventional four-wheel steering vehicles as described above, increases the rigidity of the link, simplifies the structure, and does not damage the link mechanism. The purpose is to provide a rear wheel steering device.

Means for Solving the Problems In order to solve these problems, the present invention has a cylindrical bushing filled with an elastic material fixedly installed at both ends between the inner ring and the outer ring, so that the bushings are fixed in the vehicle width direction. A pair of links extending in parallel to each other are arranged in parallel, and each of the suspension member and the axle member is provided with a central axis extending in the longitudinal direction of the vehicle through these members, and both ends of each central axis are connected to the cylinder. In a rear wheel steering system for a four-wheel steering vehicle in which a power cylinder is inserted into the inner ring of a bushing and attached to one of the links to push and pull the link in the axial direction, the power cylinder is inserted in the longitudinal direction of the link. The power cylinder is arranged inside the vehicle body on an extension line along the line, and one of the piston or cylinder body of the power cylinder is attached to the outer ring of a cylindrical bush on the suspension member side of the link.

Operation According to such a rear wheel steering device, when hydraulic oil is supplied to the working chamber of the power cylinder on the rear wheel side in response to the steering of the front wheels, the push/pull driving force of the power cylinder is applied to the central axis on the suspension member side. The elastic body of the cylindrical bushing attached to the power cylinder is flexibly deformed, and the flexural deformation of this elastic body is transmitted to the cylindrical bushing on the axle side via a link on the same extension line as the power cylinder, and the cylindrical bushing is By operating the center shaft on the axle member side by the bending deformation of the axle member, the direction of the axle member is changed and the rear wheels are steered.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. FIG. 1 is a cross-sectional view of the main parts of the rear wheel steering system according to the present invention, and the same components as those of the conventional example shown in FIGS. 2 and 2A are designated with the same reference numerals. be. Reference numerals 38 and 39 in the figure represent a pair of links, and the links 38 and 39 are arranged in parallel and extended in the vehicle width direction. this link 3
An outer ring 15 of a cylindrical bushing 17 having a structure in which an elastic body 16 is filled between an inner ring 14 and an outer ring 15 is fixed to both ends of the bushings 8 and 39.

20 is a suspension member, and 21 is an axle member. The suspension member 20 and the axle member 21 are provided with central shafts 23 and 24 that extend through these members in the longitudinal direction of the vehicle. Both end portions of the center shafts 23 and 24 in the front and back directions are inserted into each inner ring 14 of the cylindrical bush 17 in a state where they are prevented from coming off. 2
2 is an axle, and 34 is a rear wheel.

A piston rod 27a of the power cylinder 25 disposed in the opposite direction to the link 38 is attached to the outer ring 15 of the cylindrical bush 17 fixed to one of the links 38, 39, in the illustrated example, the suspension member side of the link 38. It is fixed.

This power cylinder 25 is arranged inside the vehicle body on an extension line along the longitudinal direction of the link 38, and has a function of pushing and pulling the link 38 in the axial direction.

Furthermore, inner rings 41, 41 of cylindrical bushes 40, 40, which are located on both sides of the cylindrical bush 17 and have substantially the same shape as the cylindrical bush 17, are inserted into the central shaft 23. This cylindrical bush 40,40
An elastic body 43 is provided between the inner ring 41 and the outer ring 42.
This inner ring 41,
41 grips the inner ring 14 of the cylindrical bush 17 to position the center shaft 23 in the axial direction. Further, the cylinder body 26 of the power cylinder 25 is fixed to the outer ring 41 of the cylindrical bushes 40, 40.

In addition, the power cylinder 25 and the cylindrical bush 1
7 and 40, and attach the piston rod 27a of the power cylinder 25 to the cylindrical bush 40.
It may be fixed to the outer ring 41 of.

The operation of the rear wheel steering device having such a configuration is as follows. In other words, in response to steering the front wheels,
When the rear wheel control system hydraulic circuit operates, the working chamber 28,
Hydraulic oil is supplied to and discharged from the piston 29, and the piston rod 27a connected to the piston 27 moves left and right. Then, the elastic body 16 of the cylindrical bushing 17 attached to the central shaft 23 on the side of the suspension member 20 and the elastic body 43 of the cylindrical bushes 40, 40,
43 are compressed in opposite directions and deformed,
This bending deformation of the elastic body 16 causes the power cylinder 2
It is transmitted to the cylindrical bushing 17 on the axle member 21 side via the link 38 which is on the same extension line as the piston rod 27a of No. 5, and the cylindrical bushing 17
The inner elastic body 16 is similarly deformed. Due to this bending deformation, the direction of the central axis 24 passing through the axle member 21 is changed, and the rear wheels 34 are steered as the axle 22 rotates.

In the above embodiment, only the steering mechanism for the left rear wheel has been described, but it goes without saying that the steering mechanism for the right rear wheel has a similar configuration, and these left and right rear wheels work together to achieve the effect. Nor. Also, the first
In the illustrated embodiment, a power cylinder is connected to the link 38, but a power cylinder may also be connected to the link 39.

Effects of the invention As is clear from the above explanation, according to the rear wheel steering device for a four-wheel steering vehicle according to the invention, a cylindrical bushing filled with an elastic body is fixed at both ends between the inner ring and the outer ring. A pair of links extending in the vehicle width direction are arranged in parallel, and a central axis is provided in each of the suspension member and the axle member and extends in the longitudinal direction of the vehicle through each of these members. In a rear wheel steering system for a four-wheel steering vehicle, in which both ends of the cylindrical bushing are inserted into the inner ring of the cylindrical bushing, and a power cylinder is attached to one of the links to push and pull the link in the axial direction. The cylinder is arranged inside the vehicle body on an extension line along the longitudinal direction of the link, and one of the piston or cylinder body of the power cylinder is attached to the outer ring of a cylindrical bush on the suspension member side of the link. Therefore, the operating force of the power cylinder is transmitted in a straight line in the axial direction of the link to rotate the axle member, so that no bending force is generated in the link, and the rigidity of the link can be increased.

Furthermore, the driving force of the power cylinder is transmitted to the axle through two cylindrical bushes: the cylindrical bushing on the suspension member side and the cylindrical bushing on the axle member side. The effects of external disturbances are suppressed as much as possible, and there is no wobbling of the rear wheels during rear wheel steering, thereby improving the running stability of the vehicle. Furthermore, the above effects can be achieved without making any particularly large changes to the conventional link structure.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a rear wheel steering device according to the present invention, FIG. 2 is a sectional view of a main part of an example of a conventional rear wheel steering device, and FIG. 2A is an enlarged view of a link attachment part. 14... Inner ring, 15... Outer ring, 16... Elastic body, 17... Cylindrical bushing, 20... Suspension member, 21... Axle member, 22... Axle, 23, 24... Central axis , 25...Power cylinder, 26...Cylinder body, 27...Piston.

Claims (1)

[Claims for Utility Model Registration] A cylindrical bush filled with an elastic material is fixed between the inner ring and the outer ring at both ends, and a pair of links extending in the width direction of the vehicle are arranged in parallel. Each of the member and the axle member is provided with a central axis that extends in the longitudinal direction of the vehicle through each of these members,
A rear wheel steering system for a four-wheel steering vehicle in which both ends of each of these central shafts are inserted into the inner ring of the cylindrical bushing, and a power cylinder is attached to one of the links to push and pull the link in the axial direction. The power cylinder is arranged inside the vehicle body on an extension line along the longitudinal direction of the link, and either the piston or the cylinder body of the power cylinder is attached to the outer ring of the cylindrical bush on the suspension member side of the link. A rear wheel steering device in a four-wheel steering vehicle, characterized in that the rear wheel steering device is installed in a four-wheel steering vehicle.