JPS60169311A - Rear suspension of car - Google Patents

Abstract

PURPOSE:To widen the variable range of a spring mechanism without overloading on a rubber bush, by making an arm to be supported by the car body through the rubber bush and the spring mechanism in parallel, and varying the spring force of the spring mechanism. CONSTITUTION:The rear arm 24 of a rear wheel suspension 21 is connected to a pin 28 through the first rubber bush 27, and a front arm 25 is connected to a subframe 20 through the second rubber bush 26. To a cylinder body 24a which is combined with the rear arm 24 and keeps the first rubber bush 27 surroundingly, a spring mechanism 30 is attached. When the bush 27 is deformed by the arm 24 component F1 of a lateral force F which acts on a rear wheel 22R, and the arm 24 is moved, this motion is transmitted from a spring transmitting member 31 to a torsion bar 32 through a rack 31b and a pinion 32a, as a torsion at the torsion bar 32, and the torsional reaction force of the torsion bar 32 resists against the lateral force of the arm 24.

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 driving stability, and the amount of toe-in greatly affects the steering 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 (turning performance).

On the other hand, in a car, it is desirable to have good stability when driving straight and good turning ability when turning. This is difficult, and the amount of toe-in is usually set as a compromise between the two.For this reason,
The rear wheels are supported against the vehicle body by multiple links and via elastic bodies, and when a lateral force is applied to the wheels during a turn, the elastic body is elastically deformed to reduce the amount of toe-in and improve turning performance. Compliance steer is well known, which achieves both straight-line stability and turning 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 device in which the amount of toe-in of the rear wheels is controlled by applying hydraulic pressure using oil pressure of power steering to an elastic support provided at a vehicle body mounting portion of a rear suspension device. According to this, when receiving a lateral force while traveling straight,
The amount of toe-in of the rear wheels is increased by the power steering oil pressure, which increases due to lateral forces acting on the front wheels, thereby ensuring driving stability when lateral forces are applied while driving straight ahead. However, in this case, since the power steering hydraulic pressure is used to control the deformation characteristics of the rubber bushing, the following problems arise. That is, in power steering, a hydraulic pressure is generated to counteract external forces from the tires and the road surface, so this hydraulic pressure fluctuates during driving, and the amount of toe-in of the rear wheels may change unnecessarily accordingly. In addition, from the viewpoint of steering stability, the occurrence of power steering is often suppressed as the speed increases, but in this case, as the speed increases, the toe-in tendency is suppressed and stability decreases, so it is preferable. do not have. Furthermore, when making sharp turns at low to medium speeds (such as U-turns), the power steering oil pressure tends to rise, so
The tendency of the rear wheels to toe in is exacerbated, and there is a risk that the turning performance of the vehicle may be impaired.

(Object of the Invention) The present invention was developed in view of the above-mentioned circumstances, and also in view of the fact that the higher the speed, the more important the stability is, and the lower the speed, the greater the turning performance is required. The purpose of this invention is to provide a rear suspension for an automobile that can stably control the toe-in tendency of the rear wheels in accordance with the vehicle speed.

(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 for biasing this arm in the toe change direction is connected to an arm connected to the support point via the rubber bushing, and the biasing force of this spring means is applied to the toe change adjusting means. The system is characterized in that it is controlled in accordance with the vehicle speed, and the tendency of the rear wheels to lateral close in is strengthened as the vehicle speed increases.

(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 force of the spring means, the rubber bushing can absorb the lateral force acting on the rear wheel. 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 means can be widened without imposing an excessive load on the rubber bushing, and the degree of freedom in designing the spring means is also large. Furthermore, even when the spring means fails, the rubber bushing alone can ensure sufficient steering stability of the vehicle, resulting in high reliability. Furthermore, since the lateral corner-in tendency is strengthened as the vehicle speed increases, both turning performance at low speeds and stability at high speeds can be achieved.

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

FIG. 1 is a schematic diagram showing a first embodiment of an automobile having a rear suspension according to the present invention. The front wheel steering device 1 is
A steering wheel 3 that is steered by the driver, a pinion 4a and a rack 4b that convert rotational movement of the steering wheel 30 into reciprocating movement in the vehicle width direction, and left and right tie rods 5, 5 whose base ends are connected to each end of the rack 4b. , one end is connected to the tips of the tie rods 5, 5, and the other end is connected to the left and right front wheels 2L, 2R (2L is not shown).
! A knuckle arm 6 (not shown) connected thereto is provided, and the front wheels 2L and 2R are steered in accordance with the steering operation of the steering wheel 3, as is well known.

The rear wheels 22L and 22R (22L is not shown) are supported by the vehicle body by two rear wheel suspensions, but since they 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 two front and rear suspensions that are rotatably connected to the wheel support 23 at one end and to the subframe 20 at the other end and extend in the vehicle width direction. The rear arm 24 is connected to the subframe 20 via a first rubber bushing 27 as shown in FIG.
The front arm 25 is connected to the subframe 20 via a second rubber bushing 26.

If the elastic coefficients of the first and second rubber bushes 27.26 are set appropriately, when the rear wheel 22R receives a lateral force, the toe changes (θ, A so-called compliance steer, which is known in the past, is obtained.

In the suspension of the present invention, as shown in FIG. 2, a spring means 30 is attached to a cylindrical body 24a that is coupled to the rear arm 24 and surrounds and holds the first rubber bush 27. The spring means 30 has a spring force transmitting member 31 whose tip 31a is connected to the cylindrical body 24a, and a pinion 32a at one end that meshes with a rack 31b formed at the center of the spring force transmitting member 31. It consists of a torsion bar 32 whose other end is fixed to the vehicle body, and when the first rubber bush 27 is deformed by the rear arm 24 component force F1 of the lateral force F acting on the rear wheel 22RK and the rear arm 24 is moved, this movement is The torsional reaction force of the torsion bar 32 is transmitted from the spring transmission member 31 via the rack 31b and the pinion 32a to the rear arm 24.
It is designed to resist the lateral force of

This torsion bar 32 is constricted at the center as shown in the figure, and has a constricted small diameter section 32b and a fixed side large diameter section 3.
2c is provided with splines, and a spring force adjusting body 41 that fits with both of these splines is connected to the torsion bar 3.
2 so as to be slidable in the axial direction.

A thread groove 41a is formed on one side of the spring force adjusting body 41, and a male thread 42 that meshes with the thread groove 41a is formed on one side of the spring force adjusting body 41.
is fixed to a rotating shaft of a stepping motor 430 fixed to the vehicle body. Therefore, when the stepping motor 43 is driven, the male screw 42 is rotated, and the screw adjustment body 41 slides on the torsion bar 32 in the axial direction (in the direction of arrows B and C), exposing the constricted portion 32bL0v of the torsion bar 32. The length l can be changed. When this length l changes, the spring constant of the torsion bar 32 changes, and the spring reaction force applied to the rear arm 24 also changes. Specifically, when the screw adjusting body 41 is moved in the direction of arrow B, the spring constant of the torsion bar 32 becomes smaller, and when it is moved in the direction of arrow C, it becomes larger.

The stepping motor 43 is driven by a vehicle speed sensor 51.
A signal from the controller 54 and a signal from the controller 54 which receives power supply from the battery 53 are amplified by the driver 55 and output signals are generated.

Next, the operation of the rear suspension configured as above will be explained. As shown in FIG. 3, the deflection characteristics of the first rubber bushing 27 with respect to the load in the absence of the spring means 3o are such that the load and deflection are proportional in areas where the load is small, and the deflection is not significant in areas where the load is large. On the other hand, spring means 3
The spring characteristic of the torsion bar 32 is that the torsion angle changes in proportion to the load, so that the spring force transmitting member 31
The relationship between the displacement (deflection) at the tip 31a and the load is the fourth
As shown in the figure, it is represented by a straight line on the graph. Here, when the screw adjustment body 41 is slid in the axial direction, the torsion bar 3
Since the spring constant 2 changes, the slope of the straight line in FIG. 4 changes. In this case, when the screw adjusting body 41 is moved in the direction of arrow B, the spring constant becomes smaller and the slope of the straight line is small, that is, it is easily displaced against the load (so when it is moved in the direction of arrow C, the slope of the straight line becomes large, In other words, it becomes difficult to displace due to the load.For this reason, the displacement of the cylindrical body 24a in the embodiment shown in FIG. 1 is a combination of both of the above characteristics as shown in FIG. When it is moved in the direction of arrow B, it is easily displaced by the load, and when it is moved in the direction of arrow C, it is difficult to be displaced by the load.

Now, let us consider a case where a lateral force F from the outside acts on the rear wheel 22H. This lateral force F is shared between the rear arm 24 and the front arm 25, with Fl on the rear arm 24 and F on the front arm 25.
A force of 2 (F2Fl+F2) acts. The force of Fl causes the rear arm 24 to undergo a displacement characteristic shown in FIG. 5, and the rear arm 24 moves inward to the vehicle body. At the same time, the force of F2 causes the second rubber bush 26 to bend, and the front arm 25 also moves inward to the vehicle body. Moving. At this time, by making the amount of movement of the front arm 25 different from the amount of movement of the rear arm, the amount of toe-in of the tire can be increased (or decreased). The toe-in tendency of the tire can be changed by adjusting the displacement in response to the lateral force F□.In other words, by moving the screw adjusting body 41 in the direction of arrow B, the rear arm 24 can be easily displaced by the lateral force Fl. , it is possible to improve the turning performance by weakening the lateral force 1.-in tendency, and conversely, by moving in the direction of arrow C, it is possible to strengthen the lateral force-in tendency.

In this embodiment, an actuation signal is outputted from the controller 54 to the stepping motor 43 via the driver 55 in response to a vehicle speed signal detected by the vehicle speed sensor 51, and at low speeds, the stepping motor 43 moves the screw adjusting body 41 in the direction of arrow C. The motor 43 is operated to move the screw adjusting body in the direction of arrow B as the speed increases. This makes it possible to improve steering stability by weakening the toe-in tendency at low speeds and improving turning performance, and by strengthening the toe-in tendency and improving stability at high speeds.

FIG. 6 is a schematic diagram showing a second embodiment of an automobile having a rear suspension according to the present invention, and the same parts as in the first embodiment are given the same numbers and will be described. The front wheel steering device 1 is the first
Since this embodiment is the same as the embodiment shown in FIG. 2, the explanation will be omitted, and since the rear wheel suspension 61 is bilaterally symmetrical, only the right side will be explained. The rear wheel 22R is rotatably supported by a wheel support 23, which is supported by a front arm 25 and a rear arm 24, and the front arm 25 is supported by a second rubber bush 26 as shown in FIG. The rear arm 26 is connected to the subframe 2 through a first rubber bushing 27.
Concatenate with 0.

Unlike the first embodiment, this embodiment has a cylindrical body 25a that is coupled to the forearm 25 and surrounds and holds the second rubber bushing 26.
A spring means 70 is attached to. This spring means 70 includes a spring force transmitting member 71 whose tip 71a is connected to the cylindrical body 25a, and a rack 7 of this spring force transmitting member 71.
The torsion bar 72 has a first pinion 72a that meshes with the rear wheel 22RK at one end, and a torsion bar 72 whose other end is connected to the output shaft of the stepping motor 56. K is telling me to give. The magnitude of this reaction force is given by the torsion of the torsion bar 72 given by the stepping motor 56, and on the other hand, the torsion by the stepping motor 56 is assisted by the torsion assisting means 80 so that sufficient torsion force can be applied. K Natsumata is here. The torsion assisting means 80 is provided on the torsion bar 72 and includes a control pulp 82 that selectively supplies hydraulic pressure from the hydraulic pump 80 to the oil passages 83 and 84 in accordance with the torsion of the bar 72 by the stepping motor 56, and a piston 86a. Separated right and salt cylinder chambers 85a.

The rack 86b is made up of a cylinder 85 having cylinder chambers 85a and 85b communicating with the oil passages 83 and 84, respectively, and a rod 86 having a rack 86b at the tip and connecting to the piston 86a. It meshes with the second pinion 72b provided in the.

Therefore, the rotation of the stepping motor 56 is controlled by the hydraulic pressure in the cylinder chambers 85a and 85b of the cylinder 85, which is selectively supplied from the control valve 82Vc in accordance with this rotation, from the rack 86b of the rod 86 to the second pinion that meshes with the rack 86b of the rod 86. A rotational force is applied to 72b to assist it.

On the other hand, a signal from the controller 54 that has received the vehicle speed signal detected by the vehicle speed sensor 51, the front wheel steering angle signal detected by the steering angle sensor 52, and the power supply from the battery 53 is sent to the stepping motor 56 from the driver. 55
The stepping motor 56 is operated according to the vehicle speed and the front wheel steering angle.

The operation of the second embodiment configured as above will be explained.

This embodiment is also the same as the first embodiment in that the toe-in tendency of the rear wheels is changed by adjusting the torsional force of the torsion bar to obtain an appropriate toe-in tendency depending on the driving and traveling conditions. be. However, in the first embodiment, a torsion force of 7 torsional force was applied to the rear arm 24, whereas in this embodiment, it is applied to the front arm 25, so that the torsion force is applied to the torsion bar in the direction in which the torsion force is applied. The trend change is reversed. Also, in contrast to FIG. 1, where the spring constant of the torsion bar is changed, in this embodiment, the torsion force is changed, so the forearm 25
The displacement becomes as shown in FIG.

Therefore, by checking the toe-in tendency 72 by the stepping motor 56, the motor 56 is rotated counterclockwise (
When the spring force transmitting member 71 is twisted in the direction of arrow E), the spring force transmitting member 71 has a force E'
directional force is applied, the front arm 25 tends to move inward due to the lateral force, and the toe-in tendency becomes stronger. Conversely, when the torsion bar 72 is twisted clockwise (in the direction of arrow F), the spring force transmitting member 71 has a p / direction force is applied, the inward displacement of the forearm due to the lateral force is suppressed to a small extent, and the toe-in tendency is weakened. In the present invention, an operating signal is output from the controller 54 to the stepping motor 56 according to the vehicle speed and the front wheel steering angle, and at low speeds, the toe-in tendency is weakened to improve turning performance, and at high speeds, the toe-in tendency is strengthened to improve stability. When the front wheel steering angle is small, the toe-in tendency is strengthened, and when the front wheel steering angle is large, the toe-in tendency is weakened. Thereby, the toe-in tendency can be optimally controlled according to both the vehicle speed and the front wheel steering angle, and the steering stability can be improved.

In addition, in both the first and second embodiments, since the biasing force of the torsion bar is applied directly to the arm, excessive force is not applied to the rubber bushing that supports the arm, which reduces the durability of the rubber bushing. In addition, the toe-in control range can be widened. Further, even if the torsion bar is not able to exert its biasing force due to, for example, the torsion bar being broken, the rear wheels are held by the first and second rubber butts 7, ensuring steering stability, and the reliability of the device is high.

Further, the present invention is not limited to this embodiment, and it is of course possible to use an elastic material such as rubber or a spring instead of the torsion bar.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of an automobile having a rear suspension according to the present invention, FIG. 2 is a side view of the first embodiment as viewed from arrow A, and FIGS. 3 to 5 are: The first rubber bushing alone,
A graph showing the relationship between the spring means alone and the displacement with respect to the load or lateral force at the rear arm support part. FIG. 6 is a schematic diagram showing a second embodiment of an automobile having a rear suspension of the present invention, and FIG. FIG. 8 is a graph showing displacement with respect to lateral force at the forearm support portion of the second embodiment. 1...Front wheel steering device 3...Steering 21 Rear wheel suspension 24...Rear arm 25...Front arm 30.70 ... Spring means 32.72 ... Torsion bar 43.56 ... Stepping motor

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 for an automobile is capable of toe change, and is connected to a suspension arm supported on the vehicle body via the rubber bush, and includes a spring means for biasing the arm in a direction of toe change; A rear suspension for an automobile, comprising a toe change adjusting means for changing the spring force of the means.