JPS60169310A - Rear suspension of car - Google Patents

Abstract

PURPOSE:To widen the variable range of the spring force, by making the spring force variable, as well as energizing a front arm by said spring force varying a lateral force load of the first rubber bush, and making toe-in control. CONSTITUTION:A rear wheel suspension 21 is constructed of a wheel support 23 which supports a rear wheel 22R as it can rotate freely, and front/rear two arms 24, 25, each of which extends along the lateral direction of the car body, one end and the other end thereof are rotatably connected to the wheel support 23 and a subframe 20, respectively. To a cylinder body 24a which is combined with the front arm 24 and keeps the first rubber bush 27 surroundingly, a spring mechanism 30 is attached. This spring mechanism 30 is constructed of the first spring supporting body 31, the second spring supporting body 34 which can slide freely on the supporting body 31 along the lateral direction, and right/left springs 32, 33. Then, the front wheel steering angle is detected by a front wheel steering angle sensor 51, and when the steering angle is small, the supporting body 34 is moved by operating a stepping motor 41.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rear suspension for an automobile, and more particularly to a rear suspension capable of controlling the lateral corner change characteristics of the rear wheels.

(Prior Art) The rear wheels of an automobile are normally provided with a slight amount of toe-in due to requirements for running stability, and the size of this toe-in gate greatly affects the handling characteristics. That is, the larger the toe-in amount, the stronger the understeer tendency and the better the straight-line stability. Conversely, the smaller the toe-in amount, the weaker the understeer tendency and the better the turning performance.

On the other hand, in an automobile, it is desirable to have good stability when traveling straight and good turning ability when turning, but as mentioned above, stability and turning ability are contradictory with respect to the amount of toe-in, so both should be satisfied.

The amount of toe-in is usually set as a compromise between the two. For this reason, when the rear wheels are supported to the vehicle body by multiple links and through elastic bodies, and when a lateral force is applied to the wheels during a turn, the amount of toe-in is reduced by the elastic deformation of these elastic bodies. Compliance steer is known, which is small and has good retrospective performance, achieving both straight-line stability and retrospective performance when turning.

However, such compliance steering has a problem in that even when the vehicle receives lateral force while traveling straight, the amount of toe-in decreases and straight-line stability is impaired. Therefore, there has been a proposal to deal with this problem by controlling the amount of deformation of the elastic means using hydraulic pressure or the like. For example, JP-A-57-99
．． No. 470 discloses a system in which the amount of toe-in of the rear wheels is controlled by applying hydraulic pressure using oil pressure from power steering to an elastic support provided in a vehicle body part of a rear suspension device. According to this, when a lateral force is applied while driving straight, the amount of toe-in of the rear wheels is increased by the hydraulic pressure of the power steering, which increases due to the lateral nozzles acting on the front wheels.
The advantage is that running stability can be ensured when lateral force is applied when driving straight ahead, but the elastic support of the rear wheel has the advantage that in addition to the lateral force, the above-mentioned hydraulic pressure to control the amount of toe-in is Due to the overloading, the elastic support is subjected to excessive force, resulting in a problem that the durability of the elastic support and the bottle that supports it is reduced. Therefore, it is necessary to strengthen the elastic support and the bottle, which may lead to an increase in cost. In addition, in order to widen the control range of the toe-in amount in this case, it is necessary to reduce the spring constant of the elastic support or increase the control external force (hydraulic pressure). If the control system fails, the change in the amount of toe-in with respect to the lateral force will become too large, which will actually impair driving stability.-In order to increase the external force for force control, the strength of the elastic support etc. Make it roughly large (you have to make it big, which is not very desirable).

(Object of the Invention) The present invention has been made in view of the above circumstances, and includes a spring whose spring force is variable in parallel with a rubber bush attached to the end of a suspension arm (hereinafter referred to as an arm) that supports a rear wheel. It is an object of the present invention to provide a rear suspension system for an automobile, which is equipped with a means and is capable of controlling toe-in tendency according to the front wheel steering angle, etc., without applying an excessive load to the rubber bushings.

(Structure of the Invention) The rear suspension of the present invention is a rear suspension for an automobile in which a rear wheel is supported on a vehicle body via an arm at a plurality of support points, at least one of the plurality of support points is provided.
is supported by the vehicle body via a rubber bushing, and a spring means is connected to the arm connected to the support point via the rubber bushing, and the spring means biases the arm in the direction of toe change. The system is characterized in that the control is performed by the adjustment means according to the front wheel steering angle, the lateral acceleration, or both, and thereby the amount of toe-in of the rear wheels is adjusted according to the front wheel steering angle, etc. The aim is to obtain good handling characteristics.

(Effects of the Invention) According to the present invention, the arm is supported by the vehicle body via the rubber bushing and the spring means in parallel, and by changing the spring horn of the spring means, the rubber bushing bears the burden of the lateral force transmitted from the rear wheel to the arm. Since the amount of deformation of the rubber bushing is changed by changing the amount of deformation of the rubber bushing, the variable range of the spring force can be widened without imposing an excessive burden on the strength of the rubber bushing, and problems with the durability of the rubber bushing are less likely to occur. In addition, the rubber bushing can be the same as the conventional one, and parts commonality can be maintained regardless of the presence or absence of the spring means.Furthermore, even if the control system of the spring means fails, the rubber bushing alone can keep the vehicle running. Maneuvering stability can be ensured sufficiently.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of an automobile having a rear suspension according to the present invention. The front wheel steering wave M1 is generated by the steering wheel 3 steered by the driver, the binion 4a and the rack 4 which convert the rotational movement of the steering wheel 3 into reciprocating movement in the vehicle width direction.
b, left and right tie rods 5.5 whose base ends are connected to each end of the rack 4b, one end to the tips of the tie rods 5, 5, and the other end to the left and right front wheels 2L, 2R (2L is not shown). It is equipped with a knuckle arm 6 connected to the front wheel 2L (the knuckle arm 6 connected to the front wheel 2L is not shown), and as is well known, the front wheel 2m is adjusted according to the steering operation of the steering wheel 3.

2R steering is performed.

The front wheel steering device 1 also includes a hydraulic cylinder 8 fixed to the vehicle body and two hydraulic cylinders 8 fixed to the rack 4b.
A hydraulic passage 10a that connects to the piston 9 that divides into two, and the hydraulic chambers 8a and 8b for left and right diversion, respectively.
, 10b, a control valve 11 that controls and supplies hydraulic pressure to these hydraulic passages 10a and 10b according to the steering of the steering wheel 3, and a hydraulic pump 13 that supplies hydraulic pressure to this control valve 11 via a hydraulic passage 12. A well-known power steering mechanism 7 is provided, and the movement of the tie rod 4b in the width direction is assisted by the hydraulic pressure generated in the hydraulic chambers 8a, 8b for turning left or turning right according to the steering of the steering wheel 3. It has become.

The rear wheels 22m and 22R (22L is not shown) are supported by the vehicle body by a rear wheel suspension 21, but since the left and right wheels are symmetrical, only the right side will be explained below. The rear wheel suspension 21 includes a wheel support 23 that rotatably supports the rear wheel 22R, and a wheel support 23 at one end.
It consists of two front and rear arms 24 and 25 whose other ends are rotatably connected to the subframe 20 and which extend in the vehicle width direction, and the front arm 24 is shown in FIG. 2 as seen by arrow A. to the subframe 2 via the first rubber bushing 27.
0, and the rear arm 25 is connected to the second
It is connected to the subframe 20 via a rubber bushing 26. If the elastic coefficients of the first and second rubber bushings 27.26 are set appropriately, when the rear wheel 22R receives a lateral force, the toe change (θR A so-called compliance steer, which is known in the past, is obtained.

In the suspension of the present invention, as shown in FIG.
is being pulled. This spring means 30 has a first spring support 31 whose tip 31G is rotatably connected to the cylindrical body 24a.
and the two protrusions 31a, 31 of this first spring support body 31.
a second spring support that is slidable in the width direction on the first spring support 31 between b and the protrusion 31 of the first spring support 31;
a, 31b and the right and left springs 32.a arranged between the projections 34a of the second spring support 34 located therebetween.
33, the second spring support 34 is slid in the width direction by a toe change adjusting means 40 to be described later, and the biasing force of the right and left springs 32 and 33 whose magnitude is adjusted is applied to the first spring support. 31 to the forearm 24.

The toe change adjusting means 40 is an actuator 4 actuated by the hydraulic pressure of the return path 14 of the control valve 11.
2, and the upper return side path 14 to this actuator 42
The actuator 42 has a cylinder fixed to the vehicle body and a movable rod 428, and the rod 42a is connected to the second spring support 34 to control the movement of the rod 428. The second spring support 34 is moved by.

Furthermore, the stepping motor 41 operates in response to signals corresponding to the front wheel steering angle and the lateral acceleration of the vehicle. Specifically, a front wheel steering angle sensor 51 detects the steering angle of the steering wheel 3 and issues a signal according to the steering angle, and a lateral G sensor 5 detects lateral acceleration and issues a signal corresponding to the steering angle.
These signals are processed in a certain manner by a controller 54 which receives signals from the stepping motor 2 and a power supply from the battery 53.
1 actuation signal is output. This activation signal is the driver 5
5 and then transmitted to the stepping motor 41,
This stepping motor 41 is operated according to the front wheel steering angle and lateral acceleration.

Next, the operation of the A7 suspension constructed as described above will be explained. In the absence of the spring means 30, the load/deflection curve of the first rubber bushing 27 would be as shown in FIG. Further, the load/deflection curve of only the spring means 30 is a straight line as shown in FIG. 4, and this straight line moves in parallel as the second spring support 34 moves. Specifically, the second
In response to movement of the spring support 34 in the direction of arrows B or C in FIG. 1, it is translated in a direction not indicated by arrows B and C in FIG. Therefore, in this embodiment, the deflection of the first rubber bushing with respect to the side J acting on the rear wheel and transmitted to the forearm 24 increases the spring force of the spring means 30 on the forearm 24 (see FIG. When the spring support body is slid in the direction of arrow C), the load on the first rubber bushing 27 is reduced, the amount of deformation of the first rubber bushing 27 is kept small, and the fifth
The characteristics change in the direction shown by arrow C in the figure. Therefore, the amount of movement of the forearm 24 inward of the vehicle body in response to lateral force is suppressed, and the tendency of toe-in of the rear wheels is weakened. Conversely, when the spring force of the spring means 30 on the front arm 24 is reduced, the load on the first rubber bushing 27 increases, the amount of deformation increases, and the characteristics change in one direction as indicated by arrow B in FIG. In this case, the toe-in tendency of the rear wheels is strengthened.

In the present invention, the spring force adjustment of the spring means 30, i.e. the second
The position of the spring support body 34 is controlled by the front wheel steering angle or the like. For example, the front wheel steering angle is detected by the front wheel steering angle sensor 51, and when the steering angle is small, the stepping motor 41 is activated to move the second spring support 34 in the direction of arrow B to strengthen the toe-in tendency and improve stability. When the steering angle is large, the second spring support 34 can be moved in the C direction to weaken the toe-in tendency and improve the retrospective performance. Although an example has been shown in which the toe-in tendency is not shown according to the front wheel steering angle, toe-in control may be performed according to the lateral acceleration instead of the front wheel steering angle, or both may be used in combination.

As explained above, in the rear suspension of the present invention, the spring force of the spring means 30 is applied to the front arm 24 and made variable to change the lateral force burden on the first rubber bush 27, thereby performing toe-in control. Because
The spring force of the spring means 30 does not act on the first rubber bush 27 in a ridge-like manner, so that the problem of decreased durability of the rubber bush is less likely to occur. It should be noted that the present invention is not limited to the above-mentioned embodiments, but includes various other modifications. For example, a coil spring may be used as the spring means 30, and the spring means 30 may be provided to bias the rear arm 25. Note that when the rear arm 25 is biased, the relationship between the biasing force and the toe-in characteristic is the first.
This is opposite to the embodiment shown in the figure. Furthermore, the support type of the rear wheel is not limited to the embodiment shown in FIG. 1, but can also be applied to various rear suspensions in which the rear wheel is supported on the vehicle body at a plurality of support points via arms.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the structure of an automobile steering system and rear suspension according to an embodiment of the present invention, and FIG.
A side view of the forearm support section taken along the arrow in the figure. Figures 3 and 4 are graphs showing the load and deflection characteristics of the first rubber bushing and spring means alone. Figure 5 is a graph showing the forearm support. 3 is a graph showing the relationship between the load and the deflection of the first rubber bushing. 1... Front wheel steering device 3... Steering 7...
Power steering mechanism 11... Control valve 21... Rear wheel suspension 30... Spring means 40... Toe change adjustment means 11
Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] The rear wheel is supported by the vehicle body at a plurality of support points via suspension arms, and at least one of the plurality of support points is supported by the vehicle body via a rubber bushing, so that the rear wheel is The rear suspension of an automobile is capable of toe change, and includes a spring means connected to a suspension arm connected to a support point via the rubber bushing, and biasing the arm in a direction of toe change; 1. A rear suspension for an automobile, comprising toe change adjusting means for changing the spring force of the spring means in accordance with at least one of applied lateral accelerations.