JPH06286442A - Four-link type rear suspension device for automobile - Google Patents

Abstract

PURPOSE:To provide a four-link type rear suspension excellent in traveling stability and steering responsiveness. CONSTITUTION:Front ends of a pair of the right and left upper control rods 4 expanded forward and a pair of the right and left lower control rods 5 arranged in parallel with each other are connected to a car body frame 1 via rubber bushes 7, and rear ends of the lower control rods 5 are connected to a rear axle housing 3 via rubber bushes 7. Rear ends of the upper control rods 4 are connected to end sections of a shaft laterally rotatably fitted to the center section of the upper face of the rear axle housing 3 via an elastic connecting means 11. The intersection C of extension lines of both upper control rods 4 is located behind the axis of a rear axle, thus the advance direction of an automobile is automatically corrected via the compliance steering by the lateral force, and the traveling stability is improved.

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 device for an automobile, and more particularly to a four-link type rear suspension device having a simple structure capable of enhancing running stability and maneuverability with respect to external disturbances. is there.

[0002]

2. Description of the Related Art In an automobile employing an axle suspension system, a rear axle housing is suspended on a vehicle body side via suspension springs, while the rear axle housing is supported by a pair of left and right upper control rods and a pair of left and right lower control rods. A four-link rear suspension that is connected to the vehicle body to position and hold the rear axle housing may be adopted. Among such four-link rear suspensions, the lateral rods may be simplified or omitted in a four-link rear suspension in which the pair of left and right upper control rods are gradually expanded toward the front and arranged in an eight shape. There are advantages.

In the eight-link four-link rear suspension device, 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 side wind or the like, compliance steer occurs in the rear axle. Such compliance steer is due to the rear axle pivoting around the intersection of the extension lines of the upper control rods due to the bending of the bushes interposed in the connecting portions of the control rods.

By the way, conventionally, the intersection of the upper control rods has been positioned 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, resulting in an oversteer state and a larger turning action than necessary. 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. If the front wheels are steered to correct such a deviation, lateral force is also generated by this steering, the rear wheels are steered, and the traveling direction changes inadvertently, resulting in so-called wobble. .

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. In addition, when an external force is applied to the vehicle body due to an unexpected cause, the driver has to deal with the steering operation, so that it is 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 is simple in that the compliance steer generated by lateral force can be positively used to enhance the stability against external force without impairing the maneuverability. It is an object to provide a 4-link rear suspension having a structure.

[0007]

In order to solve the above-mentioned problems, the present invention is directed to a pair of left and right upper control rods arranged so as to gradually expand toward the front and left and right arranged parallel to each other. The front ends of the pair of lower control rods are connected to the vehicle body side via rubber bushes. In addition, 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 attached to the end of a shaft horizontally movably attached to the center of the upper surface of the rear axle via elastic connecting means. Each is connected via a rubber bush. The intersection of the extension lines of both upper control rods is located behind the axis of the rear axle.

Further, in the present invention, it is desirable to provide an actuator for moving the shaft relative to the rear axle against the elastic coupling means, and a control means for controlling the actuator so as to steer the rear wheel in the same phase as the front wheel.

Furthermore, the present invention is characterized in that the sensor for outputting a signal corresponding to the running state of the vehicle and the steer direction of the rear wheels are switched and controlled according to the running state of the vehicle detected based on the output of the sensor. It is desirable to provide control means for controlling the actuator.

[0010]

[Operation] An elastic coupling means for allowing relative movement in the horizontal direction is interposed between the shaft attached to the rear end of the upper control rod via a rubber bush and the rear axle, and the intersection of the left and right upper control rods is connected to the rear axle. It is located behind the axis of.
For this reason, when a lateral force acts, the compliance steer in the direction opposite to the conventional direction is positively generated by the guiding action of the upper control rod and the elastic deformation of the elastic coupling means. Therefore, for example, with respect to cross wind, the rear wheels are steered in a direction that corrects the change in the traveling direction due to the cross wind, or the rear wheels are steered in the same direction as the steering direction of the front wheels. The driving stability of the vehicle is improved without the direction changing suddenly.

When the actuator for moving the shaft relative to the rear axle against the elastic coupling means is variably controlled in response to the running state of the vehicle, the elastic coupling is performed in response to the vehicle speed or the steering angle. The amount of deformation, the direction of deformation, or the timing of deformation of the means, that is, the steering angle of the rear wheel, the steering direction or the steering timing can be changed, so that the running stability can be improved without impairing the steering response. .

[0012]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic plan view showing an embodiment of the present invention,
2 is a side view of FIG. 1, in which a rear axle housing 3 is attached to a vehicle body frame 1 via a suspension spring 2 represented by an air spring, and the vehicle body frame 1 and the rear axle housing 3 are paired on the left and right upper control rods. 4 and a pair of left and right lower control rods 5 are connected to form a four-link rear suspension device for an automobile. 6 is a rear wheel.

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

Brackets 8 are 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 both control rods 4 and 5 are tightened and fixed to the vehicle body frame 1 with bolts (not shown), and the brackets 8 attached to the rear ends of the lower control rods 5 are attached to the rear axle housing 3 with bolts (not shown). It is fastened and fixed to.

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

FIG. 4 is a cross-sectional view showing a specific structure of the connecting portion between the rear end of the upper control rod 4 and the rear axle housing 3. The shaft 12 extends in the left-right direction at the center of the upper surface of the rear axle housing 3 via the elastic connecting means 11.
Is attached so that it can be moved 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 by the nuts 13, respectively, so that the rear end of the upper control rod 4 is fixed to the rubber bush 7, the shaft 12 and the elastic coupling means. It is connected to the rear axle housing 3 via 11. The elastic coupling means 11 is provided with a sleeve 14 fixed in the center of the upper surface of the rear axle housing 3 and extending in the left-right direction as shown in the drawing, and the shaft 12 penetrates the central portion of a rubber 15 fixed inside the sleeve 14. It is fixed.

The rubber bush 7 attached to the rear end of the upper control rod 4 is connected to both ends of the shaft 12 to change the attachment angle of the shaft 12 by elastic deformation of the rubber 15. In addition,
A collar 16 fitted to the shaft 12 is fixed to the center of the rubber bush 7 attached to the rear end of the upper control rod 4, and the collar 16 is fixed to the shaft 12 with a nut 13. .

In the four-link type rear suspension device for an automobile having the above-mentioned structure, lateral force does not act when the automobile is traveling straight without receiving an external force. Therefore,
In such a straight running state, the rear axle housing 3 is held parallel to the vehicle width direction, and the rear wheels 6 are held in the straight running state.

However, as shown in FIG. 5, when the front wheels 17 are steered to the left side in the figure while the vehicle is traveling and a centrifugal force f is generated toward the right side in the figure, a lateral force F corresponding to the centrifugal force f is generated.
Acts between the road surface and the rear wheel 6. In this way lateral force F
5, the rear axle housing 3 rotates in the direction of 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 wheels 17 are steered and the lateral force F acts on the rear wheels 6, both upper control rods 4 rotate in the clockwise direction in the figure around the front ends connected to the vehicle body frame 1, respectively. To do. Then, the shaft 12 attached to the rear axle housing 3 via the elastic coupling means 11 relatively rotates in the counterclockwise direction with respect to the rear axle housing 3. Therefore, the rear axle housing 3 coupled to the shaft 12 via the elastic coupling means 11 rotates in the counterclockwise direction and the rear wheel 6 is steered to the left as shown in FIG.

During such steering, the rubber bush 7 for coupling the lower control rod 5 to the vehicle body side and the rear axle and the rubber 15 of the elastic coupling means 11 are deformed to change the substantial lengths of both control rods 4, 5. Therefore, the lower control rod 5 does not restrain the movement of the rear axle housing 3.

The steer angle of the rear wheel 6 as described above increases as the lateral force F increases. Therefore, even with the same steering angle, the steer angle of the rear wheels 6 increases as the centrifugal force f increases as the vehicle speed increases. Further, even when an external force such as a side wind is applied during straight traveling, the rear wheels 6 are similarly steered to automatically correct the traveling direction, so that the vehicle can travel at high speed without impairing the steerability during low speed traveling. It is possible to improve the running stability at the time.

In the above embodiment, the lateral force F and the elastic coupling means 11 are used.
Although the rear wheel 6 is automatically steered to a position where the reaction force is balanced, the deformation amount and the deformation direction of the elastic coupling means 11 can be variably controlled in response to the running state of the automobile.

FIG. 6 is a schematic plan view of an essential part showing another embodiment of the present invention, in which the sleeve 14 of the elastic coupling means 11 and the rear end of one upper control rod 4 are coupled via an actuator 17. There is. And the rear wheel 6 is the front wheel 1
The vehicle is steered in the same phase as the No. 7 to improve the running stability of the automobile.

That is, the actuator 18 is composed of a double-acting hydraulic cylinder. The cylinder 14 is connected to the sleeve 14 via the pivot 19, and the tip of the piston rod 22 is connected to the upper control rod 4 via the pivot 21. Are joined together. Then, as shown in FIG. 7, each chamber formed by sandwiching the piston 23 and each cylinder chamber of the power steering unit 24 are connected through an oil passage 25 so that the rear wheel 6 is steered in phase with the front wheel 17. I have to. 26 is an oil pump and 27 is an oil tank.

Therefore, when the actuator 18 is made 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 elastically connected to the elastic coupling means 11 in the straight traveling state. In order to prevent the rear wheel 6 from being deformed and the rear wheel 6 is prevented from being steered, the rear wheel 6 is prevented from being steered even when a lateral force acts on the rear wheel 6. Therefore, even if an external force such as a side wind is applied, the traveling direction of the vehicle does not change carelessly.

However, when the front wheels 17 are steered, the rear wheels 6 are steered in phase with the front wheels 7 accordingly. Also,
The steering angle at this time is the power steering unit 24.
Changes according to the flow rate of the hydraulic oil supplied from the actuator 11 to the actuator 11, that is, the steering angle of the front wheels 17. Therefore, the rear wheels 6 are not steered more than necessary, and a sudden change in the steering feeling is prevented. When the actuator 18 is composed of a hydraulic cylinder, the power steering unit 24 can be effectively used as a control means for the actuator 18, so that it is not necessary to provide a special control means.

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 switching of 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 steer direction, the steer angle, and the steer timing of the rear wheels 6 are variably controlled in response to the vehicle speed and the steering angle. I am trying to do it.

Incidentally, the controller 29 keeps the electromagnetic switching valve 28 in the state shown in FIG. 8 when the vehicle is traveling straight ahead to allow the compliance steering of the rear axle housing 3 to move in the traveling direction by the lateral force. Although the fluctuation is automatically avoided, the actuator 11 is controlled so as to steer the rear wheel 6 in a phase opposite to that of the front wheel when turning at a low speed. Then, for example, when the front wheels 17 are steered during high-speed traveling, the actuator 11 is configured to steer the rear wheels 6 in phase with the front wheels 17 by an angle corresponding to the steering angle.
Operate.

As described above, the steer angle and the steering direction of the rear wheels 6 are variably controlled in response to the vehicle speed and the steering angle, but by steering the rear wheels 6 with a time lag with respect to the steering of the front wheels 17. It is also possible to improve driving feeling while ensuring driving stability.

In each of the embodiments, the actuator 11 is composed of 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,
Steering angle and steering direction of the rear wheels are variably controlled by variably controlling the deformation amount, the deformation direction and the deformation timing of the elastic coupling means based on the running state of the vehicle represented by the vehicle speed, the steering angle, the weight of the vehicle and the magnitude of the lateral force. Alternatively, if the steer timing is optimally controlled, the intended purpose can be achieved, and the configurations of the actuator and its control means are not limited to those in the embodiments.

[0032]

As is apparent from the above description, according to the four-link rear suspension system for a vehicle according to the present invention, the rear wheels are automatically steered when a lateral force is applied. The traveling direction of the vehicle does not change carelessly and the running stability is improved. Further, since the rear wheels are not steered when the lateral force is not applied, the steering response is not impaired.

[Brief description of drawings]

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

FIG. 2 is a side view of FIG.

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

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

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

FIG. 6 is a schematic plan view of a main part showing another embodiment of the present invention.

7 is a schematic plan view showing a specific example of the 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]

 1 Body Frame 2 Suspension Spring 3 Rear Axle Housing 4 Upper Control Rod 5 Lower Control Rod 6 Rear Wheel 7 Rubber Bushing 8 Bracket 9 Outer Cylinder 10 Eyeball Part 11 Elastic Joint Means 12 Shaft 13 Nut 14 Sleeve 15 Rubber 16 Color 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 Centrifugal force F Horizontal Power

Claims (3)

[Claims] 1. A pair of left and right upper control rods arranged so as to gradually expand toward the front,
A four-link rear suspension device for an automobile, comprising a pair of left and right lower control rods arranged in parallel with each other, wherein front ends of the upper control rod and the lower control rod are respectively coupled to a vehicle body side via rubber bushes. Then, connect the rear end of the lower control rod to the rear axle via a rubber bush, and connect the rear end of the upper control rod to the end of a shaft that is horizontally movably attached to the center of the upper surface of the rear axle via elastic coupling means. A four-link rear suspension system for automobiles, characterized in that they are connected via rubber bushes and the intersections of the extension lines of these upper control rods are located behind the axis of the rear axle. 2. An actuator for steering the rear wheel by moving the shaft relative to the rear axle against the elastic coupling means, and a control means for controlling the actuator so as to steer the rear wheel in phase with the front wheel. The four-link rear suspension device for an automobile according to claim 1, wherein 3. An actuator for moving the shaft relative to the rear axle relative to the elastic coupling means to steer the rear wheels, a sensor for outputting a signal corresponding to a running state of the automobile, and an output based on the output of the sensor. 2. The four-link rear suspension system for a vehicle according to claim 1, further comprising control means for controlling the actuator so as to switch and control the steering direction of the rear wheels in accordance with the detected running state of the vehicle. .