JPH03112708A - Suspension device for automobile - Google Patents

Abstract

PURPOSE:To enable the light and smooth operation of a rear wheel steering device by connecting the lower end of a shock absorbing device for restraining the vertical vibration of a body to a stabilizer, and connecting the end of the stabilizer to a wheel support via a control link laid in a specific direction. CONSTITUTION:A rear wheel suspension device equipped with a rear wheel steering device has a wheel support 30 for so supporting a rear wheel as to be freely rotatable, an upper arm 33, a lower arm 36, a stabilizer 37 for restraining the inclination of a body in turning and a shock absorbing device 38. In this case, the lower end of the shock absorbing device 38 is connected to the side of the stabilizer 37 extending in the front direction of the body, and the front end of the aforesaid side is connected to a wheel support 30 via a control link 49. This control link 49 is so positioned as to cause the action of a steering force generated around a king pin PK due to the inputting of the reaction of the device 38 to the stabilizer 37, in a direction opposite to the steering force, depending upon a lateral force acting on the outer rear wheel in turning.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a suspension device for an automobile equipped with a rear wheel steering device that steers both the front wheels and the rear wheels in accordance with the operation of a steering wheel.

[Conventional technology]

Conventionally, in order to reduce the steering force of the rear wheels in a rear wheel steering vehicle, as shown in Japanese Patent Application Laid-Open No. 58-214463, the caster trail of the rear wheels is made negative, and
A device configured to have a negative kingpin offset is known. That is, as shown in FIG. 12, in a side view of the right rear wheel 3R, the intersection O between the kingpin axis KP and the road surface is located on the rear side of the vehicle body than the ground contact center G of the rear wheel 3R, and the intersection 0 and the By setting the caster trail Q, which is the distance in the longitudinal direction from the center of ground contact G, to be negative, the restoring torque, that is, the self-alignment torque, generated during turning is reduced, and the steering force of the rear wheels 3R is reduced. . Further, as shown in FIG. 13, in a rear view of the rear wheel 3R, the intersection O between the kingpin axis KP and the road surface is located outside the vehicle body than the ground contact center G of the rear wheel 3R, and the intersection 0 and the ground contact center G By setting the king pin offset m, which is the distance in the left-right direction from the rear wheel 3R, to a negative value, the road surface resistance that occurs when turning the vehicle while driving is reduced, thereby reducing the steering force of the rear wheels 3R.

[If problem that the invention seeks to solve]

When the caster trail Q and kingpin offset m of the rear wheel 3R are each negative as described above, the kingpin axis KP is set to the ground contact center G of the rear wheel, as shown in FIG. Since it is offset to the rear of the vehicle body, when the vehicle is turning to the left, the rear wheel 3R is moved around the king pin @KP in response to the lateral force acting on the right rear wheel 3R located on the outside of the turn. A force A acts to steer the vehicle in the toe-in direction.

Then, when the steering force A is applied to urge the rear wheels 3R in the toe-in direction when the vehicle turns, the rear wheels 3R are
There is a problem in that when a force is applied to steer the R in the toe-in direction, a large load is placed on the rear wheel steering device.

The present invention has been made to solve the above two problems, and has a simple configuration in which a large force is applied to steer the rear wheels located on the outside of the turn around the kingpin axis when the automobile turns. An object of the present invention is to provide a suspension device for an automobile that can prevent this and reduce the load input to a rear wheel steering device.

[Means to solve the problem]

The present invention provides a suspension system for an automobile equipped with a rear wheel steering device that steers both the front wheels and the rear wheels in accordance with the operation of a steering wheel, in which a side end of a stabilizer rotatably supported by a vehicle body is connected via a control link. At the same time, the lower end of the loose Ili device that suppresses the vertical vibration of the vehicle body is connected to the above stabilizer, and the steering around the kingpin axis is generated by inputting the reaction force of this AMI position to the above stabilizer. The control link is arranged so that the force acts in the opposite direction to the steering force corresponding to the lateral force that acts on the rear wheel on the outside of the turning when the automobile turns.

[Effect]

According to the present invention having the above configuration, the steering force corresponding to the lateral force that acts when the automobile turns, and the FI that suppresses the vertical vibration of the vehicle body.
Since the steering force corresponding to the reaction force of the i-shock device is configured to act in opposite directions, the two steering forces cancel each other out, resulting in a load greater than the steering force corresponding to the lateral force. Input to the rear wheel steering mechanism is prevented.

〔Example〕

FIG. 1 shows an overall schematic diagram of a rear wheel steered vehicle. This rear wheel steering vehicle includes a front wheel steering device 2 that steers left and right front wheels 1L and 1R, and left and right rear wheels 3L.

It is equipped with a rear wheel steering device 4 that steers 3R.

The front wheel steering device 2 is driven by a steering shaft 6 that is rotationally driven by a steering wheel 5, a rack and pinion mechanism 7 that converts the rotational movement of the steering shaft 6 into linear movement, and this rack and pinion l1f17. A front wheel steering rod 8 and a pair of left and right knuckle arms 10L connected to both left and right ends of the front wheel steering rod 8 via tie rods 9L and 9R, respectively.

10R. Further, the front wheel steering device 2 is provided with a power cylinder 11 that assists the movement of the front wheel steering rod 8, and a control valve 12 that switches an oil path in accordance with the operation of the steering handle 5.

The rear wheel steering device 4 has tie rods 13L, 13R and knuckle arms 141.14R at both left and right ends, respectively.
A rear wheel steering rod 15 is connected to the left and right rear wheels 3L and 3R via a power cylinder 16 that assists the driving force of the rear wheel steering rod 15, and a power cylinder 16 that assists in rear wheel steering when a failure occurs in the rear wheel steering device 4. A centering spring 17 that biases the rod 15 to the neutral position, and a centering spring 17 that biases the rod 15 to the neutral position, and
A steering ratio variable mechanism 18 that changes the steering ratio of the rear wheels 3L and 3R relative to the rear wheels 3L and 3R is provided.

Since the structure of this variable steering ratio mechanism 18 is conventionally well known, a detailed explanation thereof will be omitted.
419 and the input shaft 21 connected to the front wheel steering rod 8 via the connecting shaft 20, and transmits its driving force to the control valve 23 of the power cylinder 16 via the control rod z2.
The rear wheel steering rod 15 is configured to be driven by a connecting member (not shown) provided on the valve casing of No. 3 in accordance with a preset steering ratio characteristic.

That is, the steering ratio variable mechanism 18
．． For example, the second
As shown in the figure, the rear wheels 3L and 3R are steered in the opposite phase direction to the front wheels 1L and 1R when the vehicle speed is between 0 and less than 351 m/h, and the rear wheels 3R are held in the neutral position at a vehicle speed of 35 b/h. 3
Rear wheels 3L and 3R are front wheel IL in the range exceeding 5KII/h.
, IR is configured to be steered in the same phase direction as IR.

The operating state of the variable steering ratio mechanism 18 is detected by the steering ratio sensor 28, and the detection signal is sent to the control unit 2.
7 and is feedback-controlled by this control section 27.

Further, a solenoid valve 29 is provided in the oil passage of the control valve 23, and this solenoid valve 29 is driven in response to a control signal output from the control section 27 when a failure occurs in the rear wheel steering mechanism 4, and the control valve 29 is actuated to control the control valve 23. 23, thereby eliminating the hydraulic pressure in the power cylinder 16 and returning the rear wheel steering rod 15 to the neutral position by the biasing force of the centering spring 17. ing.

Hereinafter, the suspension system of the present invention applied to the above-mentioned wheel-steering vehicle will be described. Figures 3 to 5 are
An example of a suspension device provided on the right rear wheel 3R is shown. This suspension device includes a wheel support 30 that rotatably supports a rear wheel 3R, an upper arm 33 consisting of a first upper arm 31 and a second upper arm 32, a lower arm 36 consisting of a 10th upper arm 34 and a 20th upper arm 35, and a rotating The stabilizer 37, which suppresses the tilting of the vehicle body, and the shock absorber 3B, which suppresses the vertical vibration of the vehicle body, are used together.

The wheel support 30 has an extension portion 39 extending above the rim portion along the inner surface of the rear wheel 3R, and a knuckle arm 14R extending from the lower end toward the side facing the vehicle body. Side ends of the rear wheel steering rod 15 are connected via a ball joint 40. The first upper arm 31 of the upper arm 33 is disposed so as to extend in the longitudinal direction of the vehicle body, and its rear end is connected to the wheel support 3 through a ball joint 41.
The front end portion is pivotally connected to the vehicle body via an elastic bushing 42. Further, the second upper arm 32 of the upper arm 33 is disposed below the first upper arm 31 so as to extend in the vehicle width direction, and its outer end is pivotally connected to the intermediate portion of the wheel support 30 via a ball joint 43. The inner end portion is pivotally connected to the vehicle body via an elastic bushing 44.

The tenth arm 34 of the lower arm 36 is arranged to extend in the longitudinal direction of the vehicle body, its rear end is pivotally connected to the lower end of the wheel support 30 via a ball joint 45, and its front #ii part is elastic. It is pivotally connected to the vehicle body via a bush 46. Further, the 20th arm 35 of the lower arm 36 is disposed behind the 10th arm 34 so as to extend in the vehicle width direction, and its outer end is pivotally connected to the lower end of the wheel support 3o via a ball joint 47. The inner end portion is pivotally connected to the vehicle body via an elastic bushing 48. And the above 1. Second upper arm 31.
32 ball joints 41 and 43, and the 1st. A kingpin axis KP is formed by a line connecting the intersection of the center lines of the 20th arm 34 and 35, and this kingpin axis K
The wheel support 30 is configured to rotate around P and the rear wheels 3R are steered.

The stabilizer 37 is disposed between the upper arm 33 and the lower arm 36 so as to extend in the vehicle width direction, and is rotatably supported by the vehicle body via a bracket 49. Further, the stabilizer 37 is provided with a side portion extending toward the front side of the vehicle body at the side end portion thereof, and the tip portion thereof is connected to the wheel support 30 via a foot roll link 49. The above is also loose! The shock absorber 50 is disposed on the rear side of the upper arm 33 and extends in the vertical direction, and a coil spring 51 is disposed on the outside of the shock absorber 50. The lower end of the shock absorber 50 is connected to the side portion of the stabilizer 37, and the upper end of the shock absorber 50 is attached to the vehicle body.

As shown in FIG. 6, the upper end of the king pin shaft KP is inclined toward the rear of the vehicle body when viewed from the side, and the intersection O between the king pin shaft KP and the road surface is lower than the ground contact center G of the rear wheel 3R. It is arranged so as to be located on the front side of the vehicle body, and the caster trail g is set to be positive. Further, as shown in FIG. 7, the king pin shaft KP has an upper end inclined inward of the vehicle body when viewed from the rear of the vehicle body, and the king pin shaft K
The intersection point O between P and the road surface is located inward of the vehicle body from the ground contact center G, and the kingpin offset m
is set correctly. As shown in FIG. 8 when viewed from above, the king pin axis KP intersects the road surface at a point O in front of the ground contact center G of the rear wheel 3R, and is located on the outside of the turn when the vehicle is turning left. Rear wheel 3R
When a lateral force acts on the rear wheel 3R, a force A is applied in response to the lateral force to steer the rear wheel 3R around the kingpin axis KP in the toe-out direction.

In addition, the side part of the stabilizer 37 is attached to the wheel support 3.
The control link 49 connected to the control link 49 is installed on the inner front side of the kingpin shaft KP with its lower end inclined inward. When the car turns, the rear wheels 3R
According to the push-up force input from above, the above is gentle! 1l123
When the reaction force of the coil spring 51 of No. 8 acts downward,
In response to this reaction force, a force is generated that pushes the front portion of the wheel support 30 downward and inward along the center line a of the control link 49, and this force causes the rear wheel 3R to move in the toe-in direction around the kingpin axis KP. A force B is applied to try to steer the vehicle.

In a rear suspension device configured to apply a force A that attempts to steer the rear wheels 3L or 3R located on the outside of the turn in the toe-out direction in response to the lateral force that acts when the vehicle turns, the lower end The control link 49 is arranged so that a force B is generated to steer the rear wheels 3L, 3R in the toe-in direction around the kingpin axis KP in response to the reaction force of the shock absorber 38 connected to the stabilizer 37. A steering force A corresponding to the above lateral force,
Il! The steering force B corresponding to the reaction force of the device 38 cancels each other out. Therefore, when the car turns,
The load input to the rear wheel steering device 4 is suppressed to a small value, thereby making it possible to stabilize the operating state of the rear wheel steering device 4. In addition, when a failure occurs in the rear wheel steering device 4, the rear wheel 3
The centering spring 17 that holds the 1.3R in the neutral position generates a steering force A corresponding to the lateral force that acts when the vehicle turns.
Since it is only necessary to set the biasing force so as to withstand the load corresponding to the difference between the steering force B and the steering force B corresponding to the reaction force of the AM device 38, the spring force is set smaller than that of the conventional Vt coil. At the same time, it is possible to reduce the burden on the hydraulic system that drives the rear wheel steering rod 15 against this spring force.

Further, the above-mentioned rear suspension device includes an upper arm 33 consisting of a first and a second upper arm 31, 32, and a first
．． It is configured as a double wishbone type with a lower arm 36 consisting of a 20th arm 34 and 35, and in addition to these four arms, the stabilizer 37 is provided, so the installation position of the shock absorber 38 is limited. However,
As described above! ! Since the lower end of the l1li device 38 is connected to the stabilizer 37,! Compared to the case where the lower end of the shock device 38 is directly connected to the wheel support 30, the degree of freedom in its installation position is increased, and it is no longer obstructed by the above-mentioned arms, etc. 11! ! The i-device 38 can be installed at a predetermined location. Moreover, the shock absorber 38 is installed in a substantially vertical state between the vehicle body and the stabilizer 37, and the direction of its operation can be matched with the direction of the vertical vibration of the vehicle body, thereby making the damping effect of the shock absorber W138 more effective. can be demonstrated effectively.

Note that the arrangement of the king pin shaft KP is not limited to the above embodiment, and various changes can be made. For example, as shown in FIG. 9, the king pin axis KP is inclined so that the upper end is located on the front side of the car body when viewed from the side of the car body, and the intersection 0 of the king pin axis KP and the road surface is the center of ground contact of the rear wheel 3R. Place the caster trail G on the rear side of the vehicle body than G.
As shown in FIG. 11, by setting the above-mentioned intersection 0 to the inside of the vehicle body from the ground contact center G and setting the king pin offset m to be positive, as shown in FIG. As shown in FIG. 12, the axis KP and the road surface may be configured to intersect at a point 0 located on the rear side of the ground contact center G when viewed from above. In this case, a force A that steers the rear wheel 3R on the outside of the turn in the toe-in direction acts around the kingpin axis KP in response to a lateral force that acts when the automobile turns. For this reason, the control link 49 is installed with its lower end inclined inward at the rear inner side of the kingpin shaft KP, and the steering force B corresponding to the reaction force of the shock absorber M38 acts in the toe-out direction. By configuring as follows, the above steering force A
and B can be made to act in a direction that strikes each other.

〔Effect of the invention〕

As described above, the present invention provides a suspension system for an automobile equipped with a rear wheel steering device, in which the lower end of the shock absorber for suppressing vertical vibration of the vehicle body is connected to the stabilizer, and the lower end of the shock absorber is connected to the stabilizer, and the lower end of the shock absorber is The control link of the stabilizer is arranged so that the steering force applied when the vehicle turns acts in the opposite direction to the steering force corresponding to the lateral force that is applied when the car turns, thereby preventing large loads from being input to the rear wheel steering system. By preventing this, the operating state of the rear wheel steering device can be stabilized, and the steering force thereof can be reduced.

Also,! ! Since the damping device is configured to be installed between the vehicle body and the stabilizer, it is possible to install the damping device III in a predetermined position within a limited space in a suspension device with a complex structure including an upper arm, a lower arm, and a stabilizer. However, there are advantages such as being able to reduce the influence of the lateral force on the rear wheel steering device.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram showing the steering system of a rear wheel steering vehicle, FIG. 2 is a graph showing the relationship between vehicle speed and steering ratio, and FIG. 3 is a side view showing an embodiment of the suspension device according to the present invention. , FIG. 4 is a rear view of the suspension device, FIG. 5 is a plan view of the suspension device, FIG. 6 is a side view showing the arrangement of the king pin shaft and stabilizer, FIG. 7 is a rear view of the same, and FIG. 8 is a rear view of the suspension device. 9 is a side view showing another example of the arrangement of the king pin shaft and the stabilizer, FIG. 10 is a rear view of the same, FIG. 11 is a plan view of the same, and FIG. 13 is a rear view of the same, and FIG. 14 is a plan view of the same. 1L, 1R...Front wheel, 3L, 3R...Rear wheel, 4...
・Rear wheel steering device, 5...Steering wheel, 30
...Wheel support, 37...Stabilizer, 3
8...Buffer device, 4...Control link, KP...Kink bin shaft.

Claims (1)

[Claims] 1. In a suspension system for an automobile equipped with a rear wheel steering device that steers both the front and rear wheels in response to steering wheel operations, the side end of the stabilizer, which is rotatably supported by the vehicle body, is connected to the wheel support via a control link. At the same time, the lower end of a shock absorber that suppresses vertical vibration of the vehicle body is connected to the stabilizer,
When the reaction force of this shock absorber is input to the stabilizer, the steering force around the kingpin shaft is generated in the opposite direction to the steering force corresponding to the lateral force that acts on the rear wheel on the outside of the turn when the car turns. A suspension device for an automobile, characterized in that the control link is arranged so as to function.