JP3157343B2 - 4-link rear suspension system for automobiles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-link type rear suspension apparatus for a motor vehicle, and more particularly to a four-link type rear suspension apparatus having a simple structure capable of improving running stability and maneuverability against disturbances. is there.

[0002]

2. Description of the Related Art In an automobile employing an axle suspension system, a rear axle housing is suspended from a vehicle body via a suspension spring, and a rear axle housing is suspended via a pair of left and right upper control rods and a pair of left and right lower control rods. In some cases, a four-link type rear suspension connected to the vehicle body to position and hold the rear axle housing is employed. Among such four-link rear suspensions, in a four-link rear suspension in which a pair of left and right upper control rods are gradually expanded toward the front, a lateral rod is simplified or omitted. There are advantages that can be done.

[0003] In the four-link type rear suspension device having the figure eight arrangement, the front wheels are steered to generate a lateral force corresponding to the centrifugal force between the rear wheels and the road surface, or
When a lateral force is generated due to a crosswind or the like, compliance steer occurs in the rear axle. Such compliance steer is caused by the rear axle rotating about the intersection of the extension lines of the upper control rod due to the bending of the bush interposed between the connecting portions of the control rods.

[0004] Conventionally, the intersection of the upper control rod is located forward of the axis of the rear axle. For this reason, the rear wheels are steered in the opposite direction to the front wheels by the lateral force generated by the steering of the front wheels, so that an oversteer state occurs and an unnecessarily large turning action is performed. Similarly, when a side wind or the like is received in a straight traveling state, a lateral force is generated and the rear wheels are steered, so that a deviation occurs between the direction of the vehicle and the traveling direction. When the front wheels are steered to correct such a deviation, lateral force is also generated by the steering, the rear wheels are steered, and the traveling direction is carelessly changed, so that a so-called wobble occurs. .

Therefore, conventionally, it was necessary to hold the steering wheel in a direction corresponding to an external force represented by a lateral force or the like. Further, when an external force is applied to the vehicle body due to an unexpected cause, the driver has to deal with the external force by steering operation. Therefore, it has been desired to realize a suspension having high stability against the external force.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and uses a compliance steer generated by a lateral force positively to improve stability against an external force without impairing maneuverability. It is an object of the present invention to provide a four-link rear suspension having a configuration.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a pair of left and right upper control rods arranged so as to gradually expand toward the front, and left and right members arranged in parallel with each other. The front ends of the pair of lower control rods are respectively connected to the vehicle body via rubber bushes. Also, attach the rear end of the lower control rod
While the rear axle is connected via the rubber bush,
Left and right through the center of the upper surface of the yaxle via elastic coupling means
The shaft along the direction is mounted so that it can move horizontally.
The rear end of the upper control rod to the end of the
Each is connected via a rubber bush.

The extension of both upper control rods
Position the intersection of the long lines behind the axis of the rear axle
With the rear axle against the elastic coupling means
That an actuator that moves the shaft relatively
Features.

A signal corresponding to the running state of the car is output.
The running state of the car detected based on the output of the force sensor
Control the actuator in response to the condition to steer the rear wheels
It is desirable to provide control means for switching the direction.

[0010]

[Function] An elastic coupling means for allowing relative movement in the horizontal direction is interposed between a shaft attached to a rear end of an upper control rod via a rubber bush and a rear axle, and an intersection of a pair of left and right upper control rods is connected to a rear axle. It is located behind the axis of.
For this reason, when a lateral force acts, compliance steering in the direction opposite to the conventional direction is positively generated by the guide action of the upper control rod and the elastic deformation of the elastic coupling means. Therefore, for example, for a crosswind, the rear wheels are steered in a direction to correct the change in the traveling direction due to the crosswind, or the rear wheels are steered in the same direction as the steering direction of the front wheels. The running stability of the vehicle is improved without a sudden change in direction.

Further , the shaft is reset against the elastic coupling means.
An actuator that moves relative to the axle is installed.
I am. Therefore, depending on the running state,
By operating, the steering angle and steering direction of the rear wheel
Maneuverability to change the steering time
Improve driving stability without impairing responsiveness
Can be. In addition, as in the invention described in claim 2, the vehicle
Control means that controls the actuator in response to the traveling state of the vehicle
If a step is provided, the rear wheel
Automatically optimizes the steering angle, steering direction or steering time
Driving operability is improved due to the ability to control
It is.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows the basic components of an embodiment of the present invention.
Schematic plan view of FIG. 2 is a side view of FIG. 1, it is attached to the rear axle housing 3 via the suspension spring 2 which is represented by an air spring to the body frame 1,
The vehicle body frame 1 and the rear axle housing 3 are connected via a pair of left and right upper control rods 4 and a pair of left and right lower control rods 5 to constitute a four-link type rear suspension device for an automobile. 6 is a rear wheel.

As shown in FIG. 1, the upper control rod 4 is disposed so as to gradually expand toward the front, and an intersection C of an extension of the upper control rod 4 is located behind the rear axle housing 3. The lower control rods 5 are arranged in parallel to each other to constitute a four-link type rear suspension device having an eight-shaped arrangement as a whole.

A bracket 8 is attached to the front end of the upper control rod 4 and both ends of the lower control rod 5 via rubber bushes 7, respectively. The brackets 8 attached to the front ends of the control rods 4 and 5 are fastened and fixed to the vehicle body frame 1 with bolts (not shown), and the bracket 8 attached to the rear end of the lower control rod 5 is attached to the rear axle housing 3 with bolts (not shown). Is fixed.

FIG. 3 is a cross-sectional view showing a specific example of the rubber bush 7, in which the outer peripheral surface of a cylindrical rubber bush 7 in which a bracket 8 is fixed through the center is covered with a metal outer cylinder 9. The outer cylinder 9 is press-fitted and fixed to, for example, a centerpiece 10 provided at an end of the lower control rod 5, so that the rubber bush 7 is elastically deformed so that the ends of the control rods 4, 5 are connected to the body frame 1 and the rear axle. It is rotatably connected to the housing 3.

FIG. 4 is a sectional view showing a specific structure of a connecting portion between the rear end of the upper control rod 4 and the rear axle housing 3. A shaft 12 extending in the left and right direction via an elastic connecting means 11 at the center of the upper surface of the rear axle housing 3.
Is mounted so that it can move horizontally. Then, the rubber bush 7 provided at the rear end of the upper control rod 4 is fastened and fixed to both ends of the shaft 12 with nuts 13 respectively.
I have. Therefore, the rear end of the upper control rod 4 is
The axle housing 3 includes a rubber bush 7, a shuff
Relative movement is possible through the
Be combined.

The elastic coupling means 11 is provided as shown in FIG.
Left and right fixed to the center of the upper surface of the rear axle housing 3
A sleeve 14 along the direction.
The center of the rubber 15 fixed inside the shaft
Are fixed through. Also, upper control
In the rubber bush 7 attached to the rear end of the rod 4
A collar 16 fitted to the shaft 12 is fixed to the core.
The collar 16 is fastened to the shaft 12 with the nut 13.
It is fixed.

In the four-link rear suspension device for an automobile having the above-described structure, when the automobile is traveling straight without receiving external force, no lateral force acts. Therefore,
In such a straight running state, the rear axle housing 3 is held parallel to the vehicle width direction, and the rear wheel 6 is held in a straight running state.

However, as shown in FIG. 5, when the front wheel 17 is steered to the left in the drawing and a centrifugal force f toward the right in the drawing is generated while the vehicle is running, a lateral force F corresponding to the centrifugal force f is generated.
Acts between the road surface and the rear wheel 6. Thus, the lateral force F
The rear axle housing 3 rotates in the direction of the arrow L about the intersection C of the extension line of the upper control rod 4 as shown in FIG.

That is, when the front wheel 17 is steered and a lateral force F acts on the rear wheel 6, the upper control rods 4 rotate in the clockwise direction around the front ends connected to the vehicle body frame 1, respectively. I do. Then, the shaft 12 attached to the rear axle housing 3 via the elastic coupling means 11 relatively rotates counterclockwise with respect to the rear axle housing 3. Accordingly, the rear axle housing 3 coupled to the shaft 12 via the elastic coupling means 11 rotates counterclockwise, and the rear wheel 6 is steered to the left as shown in FIG.

During such steering, the rubber bush 7 connecting the lower control rod 5 to the vehicle body and the rear axle and the rubber 15 of the elastic connecting means 11 are deformed and changed to the substantial lengths of the control rods 4 and 5. Therefore, the movement of the rear axle housing 3 is not restricted by the lower control rod 5.

The steering angle of the rear wheel 6 increases as the lateral force F increases. Therefore, even when the steering angle is the same, the steer angle of the rear wheel 6 increases when the centrifugal force f increases as the vehicle speed increases. Further, when the vehicle is subjected to an external force represented by a cross wind or the like during straight running, the rear wheel 6 is similarly steered and the traveling direction is automatically corrected, so that high-speed running without impairing the steering performance at low speed running is performed. The running stability at the time can be increased.

4 ribs with a rubber bush interposed at the connection
In the link-type rear suspension device,
Where the lateral force F and the reaction force of the elastic coupling means 11 are balanced
The rear wheel 6 can be automatically steered until
In the present invention, the deformation amount of the elastic coupling means 11 and
The direction of deformation can be variably controlled in response to the driving conditions of the vehicle.
And to be able to.

That is, FIG.
Specific example of the actuator 18 that moves relatively to the through hole
FIG. 3 is a schematic plan view of a main part showing a structure,
And the rear end of one upper control rod 4 are connected via an actuator 17. Then, the rear wheels 6 are steered in the same phase as the front wheels 17 so as to enhance the running stability of the automobile .

More specifically, the actuator 18 is constituted by a double-acting hydraulic cylinder. The cylinder 20 is connected to the sleeve 14 via the pivot 19, and the pivot 2 is connected to the upper control rod 4.
The distal end of the piston rod 22 is connected to the end of the piston rod 22 via the first rod.
Then, as shown in FIG. 7, the respective chambers formed with the piston 23 interposed therebetween and the respective cylinder chambers of the power steering unit 24 are connected via an oil passage 25 so that the rear wheel 6 is steered in the same phase as the front wheel 17. I have to. 26 is an oil pump and 27 is an oil tank.

Therefore, when the actuator 18 is operated to follow the power steering unit 24 to steer the rear wheel 6 in the same phase as the front wheel 17 as in this embodiment, the actuator 18 is connected to the elastic coupling means 11 in the straight traveling state. In order to prevent the deformation of the rear wheel 6 and prevent the rear wheel 6 from being steered, the rear wheel 6 is prevented from being steered even if a lateral force acts due to a cross wind or the like. For this reason, even if it receives an external force such as a crosswind, the traveling direction of the vehicle does not change carelessly.

On the other hand, when the front wheels 17 are steered, the rear wheels 6 are steered in phase with the front wheels 7. The steering angle at this time changes in accordance with the flow rate of the hydraulic oil supplied from the power steering unit 24 to the actuator 11, that is, the steering angle of the front wheels 17. For this reason, the rear wheel 6 is not steered more than necessary, and a sudden change in the steering feeling is prevented. When the actuator 18 is formed of a hydraulic cylinder, the power steering unit 24 can be effectively used as a control unit of the actuator 18, and there is no need to provide a special control unit.

FIG. 8 shows another control means for the actuator 8. In this embodiment, an electromagnetic switching valve 28 is provided in the oil passage 25, and a controller 29 that controls the electromagnetic switching valve 28 is provided. And the vehicle speed sensor 3
By supplying the vehicle speed signal output from 0 and the steering angle signal output from the steering sensor 31 to the controller 29, the steering direction, the steer angle and the steer timing of the rear wheel 6 are variably controlled in response to the vehicle speed and the steering angle. I am trying to do it.

When the vehicle is running straight, the controller 29 keeps the electromagnetic switching valve 28 in the state shown in FIG. 8 to permit the compliance steer of the rear axle housing 3 to move in the traveling direction due to the lateral force. Although the fluctuation is automatically avoided, the actuator 11 is controlled so that the rear wheel 6 steers in the opposite phase to the front wheel when turning in a low speed state. For example, when the front wheel 17 is steered during high-speed traveling, the actuator 11 is steered so that the rear wheel 6 is steered in the same phase as the front wheel 17 by an angle corresponding to the steering angle.
Activate

The steer angle and the steer direction of the rear wheel 6 are variably controlled in response to the vehicle speed and the steering angle as described above, but by steering the rear wheel 6 with a time lag with respect to the steering of the front wheel 17. In addition, the driving feeling can be further improved while ensuring the running stability.

In each of the embodiments, the actuator 11 is constituted by a hydraulic cylinder and the power steering unit 24 is used as a part of the control means to simplify the structure of the control means. Control means can also be used. That is,
The amount and direction of deformation of the elastic coupling means and the timing of deformation are variably controlled based on the running state of the vehicle represented by the vehicle speed, steering angle, vehicle weight, and the magnitude of lateral force, and the steering angle and steering direction of the rear wheels are controlled. Alternatively, if the steering time is optimally controlled, the intended purpose can be achieved, and the configurations of the actuator and its control means are not limited to the embodiment.

[0032]

As is apparent from the above description, according to the four-link type rear suspension device for a vehicle according to the present invention, the shaft is connected to the rear axle against the elastic coupling means.
Actuator that moves the rear wheel by moving it relatively
To change the steering characteristics of the rear wheels.
To reduce running stability.
Operation according to driving conditions or driver's preference
Longitudinal characteristics can be obtained. Further, according to the second aspect,
According to Ming, the rear wheels steer according to the driving conditions of the car.
Optimal control of angle, steer direction or steer timing
Driving stability without compromising maneuvering responsiveness
Sex can be made higher.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a basic component showing an embodiment of the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is a sectional view showing a specific example of a rubber bush.

FIG. 4 is a sectional view showing a specific structure of a coupling portion between an upper control rod and a rear axle housing.

FIG. 5 is a schematic plan view illustrating the behavior of the rear axle held by the four-link type rear suspension device for a vehicle according to the present invention.

FIG. 6 is a schematic plan view of a main part showing a specific structure of an actuator .

FIG. 7 is a schematic plan view showing a specific example of a control mechanism of the actuator shown in FIG.

8 is a schematic plan view showing another specific example of the control mechanism of the actuator shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Body frame 2 Suspension spring 3 Rear axle housing 4 Upper control rod 5 Lower control rod 6 Rear wheel 7 Rubber bush 8 Bracket 9 Outer cylinder 10 Eyeball part 11 Elastic coupling means 12 Shaft 13 Nut 14 Sleeve 15 Rubber 16 Collar 17 Front wheel 18 Actuator 19 Pivot 20 Cylinder 21 Pivot 22 Piston rod 23 Piston 24 Power steering unit 25 Oil passage 26 Oil pump 27 Oil tank 28 Electromagnetic switching valve 29 Controller 30 Vehicle speed sensor 31 Steering sensor C Intersection of extension line of upper control rod 4 f Centrifugal force F Side Power

Claims (2)

(57) [Claims] 1. A pair of left and right upper control rods disposed so as to gradually expand toward the front,
A four-link type rear suspension device for a vehicle having a pair of left and right lower control rods arranged parallel to each other, wherein front ends of the upper control rod and the lower control rod are respectively connected to a vehicle body via rubber bushes. Then, the rear end of the lower control rod is connected to the rear axle via a rubber bush, and the rear end of the upper control rod is connected to the end of a shaft horizontally movably attached to the center of the upper surface of the rear axle via elastic connecting means. binding, respectively, via a rubber bush
And the intersection of the extension lines of both upper control rods is located behind the axis of the rear axle.
Position the shaft relative to the rear axle against the coupling
A four-link type rear suspension device for an automobile, comprising an actuator for moving and steering a rear wheel . 2. A signal corresponding to a running state of an automobile is output.
Vehicle running state detected based on the output of a running sensor
Control the actuator in response to the
2. A four-link type rear suspension device for an automobile according to claim 1, further comprising control means for switching control of the vehicle.