JPH0732336Y2 - 4-wheel steering system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a four-wheel steering device for a passenger car or the like that can realize not only front wheel steering but also rear wheel steering at low cost and easily.

<Prior Art> In a general vehicle provided with two axles, steering wheels normally attached to either one of the axles,
The traveling direction can be arbitrarily selected.

Further, in recent years, a four-wheel steering system has been realized in which all wheels can be steered for the purpose of improving running performance and comfortable driving when turning or changing routes during high-speed running.

Currently known four-wheel steering devices of this type are both mechanically or electrically controlled by associating steering of the front wheels and steering of the rear wheels. And one of the above-mentioned steerings, in which the same-phase steering that makes the steering direction of the rear wheels the same and the opposite-phase steering that makes the steering direction of the front wheels and the steering direction of the rear wheels opposite are switched according to the vehicle speed. There was something to do.

FIG. 5 shows a concept of an example of such a conventional four-wheel steering system. In the device shown in FIG. 5, when the steering wheel 10 is rotated to steer the front wheel 1 by the cylinder rod 5 via the ball joint 40 and the tie rod 6 shown in FIG. This is to steer two, which will be specifically described below.

A steering wheel linkage 9 of a vehicle shown in FIG. 5 has a power cylinder 7 for assisting the steering force and a steering gear linkage 9 incorporating a switching valve (not shown) for switching the oil supply to the power cylinder 7. The switching valve is connected to the oil pump 11a and the oil reservoir 12a located on the upper side in FIG. 5 through a pair of pipes 30a, and at the same time, the oil feed direction from the oil pump 11a to the power cylinder 7 is changed. Have control. A control valve 13 for controlling the operation of the power cylinder 15 for steering the rear wheels with an internal spool 13a is connected to the power cylinder 7 via a pair of pipes 30.
An oil pump 11b and an oil reservoir 12b, which are located in the middle of FIG. 5 and are driven by an engine (not shown), are connected to 13 together with the oil pump 11a. Power cylinder 15
The rear cylinder rod 4 is connected to a trailing arm 3 that supports the rear wheel 2 and steers the rear wheel 2 by sliding.
Is supported through.

Therefore, the steering wheel 10 is operated to move the cylinder rod 5 which is the piston rod of the power cylinder 7 to the fifth position.
In the figure, when moved to the left or right, the switching valve opens and the piping 30a
Will supply the hydraulic oil to the power cylinder 7, and as a result, the driving force of the cylinder rod 5 will be increased.
The front wheels are steered via the tie rods 6. And
When the steering force of the front wheels 1 exceeds a certain value, the spool 13a of the control valve 13 is displaced via the pipe 30,
The hydraulic oil from the oil pump 11b is supplied into the power cylinder 15 so that the steering force is exerted and the rear wheels 2 are steered.

<Problems to be Solved by the Invention> In the structure shown in FIG. 5, the power cylinder 7 attached to the steering gear linkage 9 for steering the front wheels 1 operates, and the power cylinder 7 accordingly.
The spool 13a of the control valve 13, which is connected to the valve via the pipe 30, is operated. This operation requires a complicated hydraulic circuit in which the rear cylinder rod 4 of the power cylinder 15 connected to the control valve 13 is slidably displaced and exerts a steering force to steer the rear wheel 2 via the trailing arm 3. I was trying.

Therefore, in the four-wheel steering device having the conventional structure, there is a problem that the labor for mounting the four-wheel steering device on the vehicle is large and the manufacturing cost is excessive, and the labor for repairing and inspecting is also large. In addition, there is also a problem that the vehicle weight increases due to the complicated structure and the economical efficiency such as fuel consumption deteriorates.

<Means for Solving the Problems> A four-wheel steering device according to the present invention is a four-wheel steering device having a member for steering front wheels and a member for steering rear wheels, one end of which is connected to a member for steering the front wheels. A push-pull wire whose other end is connected to a member for steering the rear wheel and can transmit a steering amount to the front wheel to the rear wheel side, and an outer cable which is held by the vehicle body and slidably penetrates the push-pull wire. And a ball joint that connects a cylinder rod that is provided in a member that steers the front wheel and that is displaced in the vehicle width direction in conjunction with the rotation operation of the steering wheel, and a tie rod that transmits the displacement of the cylinder rod to the front wheel side, It is provided between the fitting fixed to the cylinder rod together with the fitting, and between the connecting portion formed on the fitting and one end of the push-pull wire. An elastic member capable of absorbing a certain amount of steering with respect to the front wheels and transmitting it to the rear wheels is provided.

<Operation> When a member for steering the front wheel is displaced by a small amount, the front wheel is steered by a small amount, but the push-pull wire whose one end is attached to this member via an elastic member slides due to elastic deformation of the elastic member. The displacement is absorbed and does not slide on the outer cable. Therefore, the sliding displacement is not transmitted to the member that steers the rear wheels, and the rear wheels are not steered.

On the other hand, when the member that steers the front wheels is slidably displaced,
The elastic member is elastically deformed by a certain amount or more, and the member for steering the front wheels and the push-pull wire slide together. Therefore, the front wheel is steered and the sliding displacement is transmitted to the push-pull wire via the elastic member, so that the push-pull wire slides with respect to the outer cable. Therefore, the sliding displacement is transmitted to the member for steering the rear wheel, which is connected to the other end of the push-pull wire, and the rear wheel is steered.

<Embodiment> An embodiment of a four-wheel steering system according to the present invention is shown in FIGS.
A description will be given based on the figure. The same members as those of the conventional technique are designated by the same reference numerals, and duplicate description will be omitted.

The pair of left and right front wheels 1 are connected to a cylinder rod 5 of the power steering device via a pair of left and right tie rods 6, respectively, and a part of the cylinder rod 5 penetrating the power cylinder 7 has a steering wheel in a steering gear linkage 9. A rack (not shown) that meshes with a pinion (not shown) that rotates together with the rack 10 is formed. Therefore, when the steering wheel 10 is rotated for steering, the pinion of the steering wheel 10 rotates within the steering gear linkage 9, and the cylinder rod 5 that forms a rack meshing with the pinion slides leftward and rightward in FIG. . As a result, the front wheels 1 are steered via the tie rods 6.

Further, the steering gear linkage 9 has a built-in switching valve (not shown) for switching the injection direction of the hydraulic oil from the oil pump 11a with respect to the power cylinder 7, and the rotation of the steering wheel 10 causes the oil pump 11a to feed oil. Since the generated hydraulic oil presses the piston 7a of the cylinder rod 5 located in the power cylinder 7 in the steering direction, the cylinder rod 5 is rotated left or right by the pressing force of the hydraulic oil together with the rotational force applied to the steering wheel 10. Then, the front wheels 1 are steered.

As described above, the rotation of the steering wheel 10 is transmitted to the cylinder rod 5, and the sliding of the cylinder rod 5 steers the pair of left and right front wheels 1 through the tie rods 6 to configure the front wheel steering member. ing.

A ball joint 40 having one end rotatably supporting the tie rod 6 and the other end having a screw 40a is located at one connecting portion between the cylinder rod 5 and the tie rod 6 shown in FIG. The screw 40a penetrates the mounting hole 35a formed in the mounting fixture 35, and the hole portion 5 provided in the cylinder rod 5
It is screwed to a. That is, the ball joint 40 that supports the tie rod 6 is a fixture between the cylinder rod 5 and the ball joint 40.
It is screwed to the cylinder rod 5 while sandwiching 35.

Further, a pair of pin receiving portions 35c each having a fixing hole 35b are provided on the tip end side of the fixture 35, and both ends of the pin 42 are fitted in the fixing hole 35b. An elastic bush 41 having a rubber portion 41a is provided on the outer periphery of the pin 42, and one end of a push-pull wire 8a is attached to the elastic bush 41 to transmit the sliding displacement of the cylinder rod 5 to the rear wheel 2. There is.

The push-pull wire 8a is installed so as to slidably penetrate the inner peripheral side of a flexible cylindrical outer cable 8b. In the present embodiment, the outer cable 8b is fixedly supported on the power cylinder 7 at one end by way of a fixing tool 55 and at the rear wheel 2 side while being fixedly supported by a not-shown vehicle body at fixed intervals through a fixing tool (not shown). Is growing.

Therefore, when the sliding amount of the cylinder rod 5 is less than a certain amount, only the rubber portion 41a of the elastic bush 41 is elastically deformed and the push-pull wire 8a does not slide, but the sliding amount of the cylinder rod 5 exceeds the certain amount. With the elastic deformation of the rubber portion 41a, the push-pull wire 8a slides in the outer cable 8b in its axial direction, and the displacement and force of the cylinder rod 5 are transmitted. Further, due to the elasticity of the rubber portion 41a, there is a dead zone where steering of the front wheels is not transmitted, but the width of this dead zone can be changed by changing to another elastic member having a different elastic coefficient.

On the other hand, a trailing arm 3, an upper arm 31a and a lower arm 31b are connected to the pair of left and right rear wheels 2, respectively. A connecting rod 3b is rotatably connected to the trailing arm 3 via a connecting pin 3c, and the connecting rod 3b, the upper arm 31a, and the lower arm 31b are connected to a cross member 33 of the vehicle body. The trailing arm 3 has a centering piston 4a.
Both ends of a rear cylinder rod 4 which forms a part of a member for steering the rear wheels are connected to each other,
The rear wheels 2 are steered by the left and right movements of the rear cylinder rod 4.

Further, a pair of compression coil springs 14b, 14c for urging the centering piston 4a toward the central portion of the actuator 14 are attached to the actuator 14 which slidably houses the centering piston 4a.

The other end of the outer cable 8b is fixedly supported by the actuator 14 via a fixture 36.
As shown in FIG. 4, the other end of the push-pull wire 8a projects from the other end of the 8b.

A base end of a lever 16 that forms a sliding displacement amount conversion mechanism and slides on the rear cylinder rod 4 is pivotally attached to a cylinder shoe 14a of the actuator 14 via a rotation center pin 17c. At the tip of the lever 16, the other end of the push-pull wire 8a is pin 1 through the elastic bush 18a.
Connected by 7a. The rear cylinder rod 4 is connected to the lever 16 via a pin 17b surrounded by an elastic bush 18b. In the present embodiment, the rotation center pin 17c and the pin 17b correspond to the distance between the rotation center pin 17c and the pin 17a. The distance between is set short.

As a result, the sliding amount of the rear cylinder rod 4 from this sliding is reduced with respect to the sliding amount of the other end of the push-pull wire 8a, and the force transmitted from the push-pull wire 8a to the rear cylinder rod 4 is expanded. The Rukoto.

Therefore, rotate the steering wheel 10 a certain amount or more,
When steered, one end of the push-pull wire 8a is shown in FIG.
While moving and displacing to the left or right, the other end of the push-pull wire 8a, which is integrally connected, slides from this one end, and the lever 16 connected to this other end is elastic bush 4
With the elastic deformation of 1,18a and 18b, the rotation center pin 17c rotates. As a result, the rear cylinder rod 4 of the actuator 14, which is in contact with the lever 16, slides to the right or left in FIG.

At this time, the push-pull wire 8a and the rear cylinder rod 4 slide in a straight line, whereas the lever 16 rotates in an arc shape. 4, a positional deviation occurs in the vertical direction between the lever 16 and the lever 16, but this deviation can be absorbed by elastic deformation of the elastic bushes 18a, 18b. The sliding amount of the rear cylinder rod 4 corresponds to a lever ratio which is a ratio of a distance between the rotation center pin 17c and the pin 17b to a distance between the rotation center pin 17c and the pin 17a. By changing the length and the height of the fixture 36, the sliding amount of the rear cylinder rod 4 with respect to the sliding amount of the cylinder rod 5 can be easily changed.

From the above, when the steering wheel 10 is rotated and the rear cylinder rod 4 slides left or right, the rear cylinder rod 4 pushes or pulls back the connecting pin 3c, and as a result, the rear wheel 2 supported by the trailing arm 3 is steered. Will be done.

For example, when the rear cylinder rod 4 slides to the left in FIG. 1, the left connecting pin 3c moves to the left, whereby the left rear wheel 2 rotates in the counterclockwise direction in FIG. 1 and is steered. At the same time, the right connecting pin 3c is pulled back and moved to the left, whereby the right rear wheel 2 is rotated counterclockwise in FIG. 1 and steered.

Furthermore, according to the four-wheel steering system of the above embodiment, the front wheels 1
Cylinder rod 5 steers the rear wheel 2
Since 14 is driven, the rear wheels 2 can be lightly steered by applying the steering force of the power steering device for steering the front wheels.

Further, in the four-wheel steering system according to the present embodiment, when the front wheels 1 are steered to the left, the push-pull wire 8a turns into the outer cable 8b.
And the amount of protrusion of the push-pull wire 8a increases from the other end of the outer cable 8b. Therefore, the rear cylinder rod 4 slides to the left via the lever 16 and the rear wheels 2 are also steered to the left for in-phase steering.
Alternatively, by mounting the outer cable 8b to the actuator 14 in a direction opposite to that of this embodiment, it is possible to perform reverse phase steering. Even in this case, the sliding displacement and the transmission of force are not affected because the push-pull wire 8a having flexibility is used.

Further, in this embodiment, the elastic member is the elastic bush 41 having a rubber portion, but the actuator 14 or other well-known means such as a spring may be used.

As described above, the rear wheel 2 can be steered with the dead band having a certain width due to the interposition of the elastic member, and appropriate rear wheel steering can be performed according to the type of vehicle.

<Effect of the Invention> According to the four-wheel steering system of the present invention, the push-pull wire that is connected to the member for steering the front wheels and can transmit the steering amount to the front wheels to the rear wheels is provided. A fitting that is fixed together with the cylinder rod by a ball joint that connects the cylinder rod that moves in the vehicle width direction in conjunction with the tie rod that transmits the displacement of this cylinder rod to the front wheel side is provided. Since an elastic member that absorbs a certain amount of steering for the front wheels and transmits it to the rear wheels is interposed between the and, the fixture for easily attaching the push-pull wire without substantially modifying the member for steering the front wheels. Also, elastic members can be attached, and fine steering operations on the front wheels can be absorbed and only large steering operations can be transmitted to the rear wheels, thereby making it possible to drive the vehicle. Row stability can be improved.

Further, since the member that steers the front wheels and the member that steers the rear wheels are connected by the push-pull wire embedded in the outer cable, the rear wheels can be steered with a simple structure. Therefore, the labor for mounting the four-wheel steering device on the vehicle is reduced, the manufacturing cost is reduced, the labor for repairs, inspections, etc. is reduced, and the weight of the vehicle can be reduced.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a vehicle using a four-wheel steering system according to an embodiment of the present invention, FIG. 2 is a sectional view of a connecting portion of a four-wheel steering system according to one embodiment of the present invention, and FIG. 2 is a sectional view of the fixture in FIG. 2 taken along the line AA, FIG. 4 is a partial sectional view of an actuator of a four-wheel steering system according to an embodiment of the present invention, and FIG. FIG. 6 is a conceptual view of a vehicle using the device, and FIG. 6 is a cross-sectional view of a connecting portion of a four-wheel steering device according to the related art. In the drawings, 1 is a front wheel, 2 is a rear wheel, 3 is a trailing arm, 4 is a rear cylinder rod, 5 is a cylinder rod, 6 is a tie rod, 7 and 15 are power cylinders, 8a is a push-pull wire,
8b is an outer cable, 10 is a steering wheel, 14 is an actuator, 16 is a lever, 18a, 18b and 41 are elastic bushes, and 35 is a fixture.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-58-164478 (JP, A) JP-A-64-32974 (JP, A) JP-A-62-279173 (JP, A) Actual development Sho-61- 66065 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A four-wheel steering system having a member for steering front wheels and a member for steering rear wheels, wherein one end is connected to a member for steering the front wheels and the other end is a member for steering the rear wheels. A push-pull wire that is connected to transmit the steering amount to the front wheels to the rear wheels, an outer cable that is held by the vehicle body and slidably penetrates the push-pull wire, and a member that steers the front wheels. A fixture fixed together with the cylinder rod by a ball joint that connects a cylinder rod that is displaced in the vehicle width direction in conjunction with the rotation operation of the steering wheel and a tie rod that transmits the displacement of the cylinder rod to the front wheel side, The rear wheel side is provided between the connecting portion formed on the fixture and one end of the push-pull wire to absorb a certain amount of steering amount for the front wheel. 4-wheel steering system, characterized by comprising an elastic member that can transmit.