JPS62289414A - Rear suspension for automobile - Google Patents

Abstract

PURPOSE:To attempt improvement of controllability and safety in a rear wheel drive car where a front and a rear link are adapted to support a rear wheel via elastic members in such a way as to be freely oscillated up and down by providing the elastic members while they are revolvingly displaced whereby changing a spring constant in the load input direction depending on acceleration. CONSTITUTION:In a rear wheel drive car where a front and a rear link 2 and 3 extending in the car width direction are adapted to secure a rear wheel 1 to the member 5 on a car body side via elastic members in such a way as to be freely oscillated up and down, the structure is constituted to be such that a spring constant in the load input direction from the links is changed by revolving the elastic members 7, which are provided respectively for the mounting sections of each link 2 and 3 to the member 5 on the car body side, around the oscillating center of the links. And displacement in revolution of said elastic members 7 is effected through a link mechanism with an electric motor 9 actuated. And the electric motor 9 is controlled by a controller 20 receiving the output from an acceleration sensor 19 in such a way that the spring constant of a front side elastic member 7 is made lower than that of a rear side elastic member 7 depending on acceleration at the time of acceleration.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to a rear suspension for an automobile.

2. Description of the Related Art In a rear suspension of an automobile in which the rear wheel is supported by a vehicle body side member via a swinging member such as an arm or a link, a rubber bush or the like is interposed at the support point of the swinging member to the vehicle body side member. Setting the spring characteristics of the elastic member has a large effect on changes in the toe angle of the rear wheels caused by lateral forces when the vehicle turns.

Therefore, a hollow part is formed in the rubber bushing interposed at the support point of the swinging member to the vehicle body side member, and a structure is adopted in which hydraulic pressure can be introduced into the hollow part, and by controlling the hydraulic pressure, the hardness of the rubber bushing can be made variable. JP-A-60-146707 discloses a system that controls the toe angle change of the rear wheels in response to lateral force so that the toe-in tendency is strengthened at high speeds and the toe-in tendency is weakened during large steering turns. , 4￥ Open and Close Publication No. 60-146708, etc.

Problems to be Solved by the Invention However, in the system of introducing hydraulic pressure into the hollow part formed in the rubber bushing as described in 1 above, if high hydraulic pressure continues to be maintained in the hollow part of the rubber bushing, the durability of the rubber bushing becomes low. However, it not only involves problems such as the oil resistance of the rubber bushing itself, but also has the problem that it is basically extremely difficult to realize a correspondence between the hydraulic pressure and the spring characteristics of the rubber bushing.

Furthermore, there is a problem in that simply controlling the change in the toe angle of the rear wheels using the vehicle speed or steering angle cannot accurately respond to all driving modes of the vehicle.

The present invention aims to address the conventional problems as described above.

Means for Solving the Problems The present invention is equipped with a parallel link type rear suspension in which the rear wheels are supported by two links on the front side and the rear side to the vehicle body side members so as to swing 1-down OT fE. In wheel drive type automobiles, one or both of the front and rear elastic members interposed in the shaft attachment portion of each rear link to the vehicle body side member are rotated around the swing center line of the link. The structure is such that the spring constant in the direction of load input from the link changes by rotation, and the elastic member is rotationally displaced relative to the link in accordance with the acceleration of the vehicle, and the spring constant is changed in the direction of load input from the link during accelerated driving. The present invention is characterized in that an actuator is provided that causes the spring constant of the front elastic member to be lower than the spring constant of the rear elastic member.

Effect As a result of the above, the amount of deflection of the elastic member due to the lateral force acting on the rear wheel during acceleration turning is larger in the front elastic member than in the rear elastic member, and the rear wheel changes the toe angle in the same direction as the front wheel steering direction. The oversteer tendency of a rear wheel drive type automobile during acceleration turning is corrected by the change in the toe angle of the rear wheels, thereby obtaining steering characteristics in which the turning radius does not change.

Example Hereinafter, embodiments of the present invention will be described with reference to both figures.

1 to 4 show an embodiment of the present invention, and in FIG. 1, l is a rear wheel, and the tips of front and rear links 2 and 3 are pivoted to the rear wheel l. , the previous and next links 2
The proximal ends 21 and 31 of 3 and 3 are attached to a shaft 6 supported by a vehicle body side member 5 such as a cross member through an elastic member 7 as shown in FIG. It is being 4 is the rotation axis of the rear wheel 1.1.

In addition, the tip of a radius rod 8 is attached to the rear wheel 1 so that the base end 81 can swing 1F to the 1I body side member in front (or behind) of the rear wheel via an elastic member. The radius rod 8 is configured to support the load acting in the longitudinal direction.

As shown in FIG. 2, the craving member 7 includes an inner cylinder 71, an outer cylinder 72 concentric with the inner cylinder 71, and a rubber or the like interposed and fixed between the inner cylinder 71 and the outer cylinder 72. For example, as shown in FIG. 2(a), a gap 73a may be formed in a part of the elastic ring 73, or a second
As shown in FIG. is configured such that the spring constant changes depending on the angle, such as a high spring constant, and when the elastic member 7 is interposed between the shaft 6 and the link base end, By rotating the elastic member 7, it is possible to variably control the spring constant of the elastic member 7 relative to the main load on the rear wheel input via the link.

Although an electric motor or a hydraulic device may be used as the actuator for rotating the valve distributing member 7, the illustrated embodiment shows an example in which an electric motor 9 is used.

That is, the electric motor 9 is attached to the vehicle body side member 5, and the electric motor 9 is
The elastic member 7 is rotationally displaced with respect to the link base end via ilO, the link mechanism 11, and the like.

FIG. 3 shows an example of the mounting portion of the elastic member 7.

That is, as shown in FIG. 3, the shaft 6 is rotatably fitted and supported via a bearing 13 on a cylindrical member 12 fixed to the body side member 5 by welding or the like, and elastic Part 7
The inner cylinder 71 of the link mechanism 11 is fitted in the L stage by means of serration fitting or the like, and the base end of the driven arm llc of the link mechanism 11 is fitted to one end of the recessed shaft 6 by means of serration fitting or the like. The nuts 14 are screwed onto the threaded portions at both ends of the shaft 6 and tightened to fix the elastic member 7, the driven arm llc, etc.

Of the elastic members 7 assembled and fixed to both ends of the shaft 6 as described above, a spherical collar 15 is press-fitted into the outer cylinder of the front elastic member 7a, and a retainer 16 is placed on the outer peripheral surface of the spherical collar 15. The base end 21 of the front link 2 is inserted and assembled so that it cannot rotate, and the spherical collar 15 is press-fitted into the outer cylinder of the rear elastic member 7b. The base end portion 31 of the rear link 3 is fitted and assembled so as to be rotatable through the rear link 3.

In Fig. 3, reference numeral 17 indicates the driven arm llc of the link mechanism 11 and the connecting rod (having a length adjustment mechanism) l.
The other end of the connecting rod Ilb is connected to the tip of the driving arm lla fixed to the output shaft of the reducer lO, as shown in FIG. 1(o). are connected via. 18 is an oil seal.

The electric motor 9 is configured to have its rotation direction, rotation angle, etc. controlled by an output signal from a controller 20 based on an acceleration signal from an acceleration sensor 19 that detects the time rate of change in vehicle speed and generates an acceleration signal corresponding to the rate of change over time. .

, the front and rear elastic members 7 on the left side are respectively 7a.
, 7b, and the front and rear elastic members on the right side are 7a' and 7b, respectively.
b', and the left and right elastic members 7b and 7b' on the rear side are assembled and fixed to the shaft 6 with a phase shift of 90''j from the left and right elastic members 7a and 7a' on the front side.

For example, during steady driving other than during acceleration driving, Fig. 4 (
As shown in b), both the front left and right elastic members 7a, 7a' and the rear left and right elastic members 7b, 7b' have an intermediate spring constant in the direction of the main load input from each link, that is, in the axial direction of the link. (a spring constant between a low spring constant and a high spring constant).

In this state y5, the elastic member 7a is caused by the cornering force as a lateral force acting on the rear wheel 1.1.

The amount of deflection of 7a', 7b, and 7b' is the same, and the toe angle of the rear wheel does not change when turning.

When the acceleration state is reached and the acceleration sensor 19 emits an acceleration signal, the controller 20 emits an output signal and the electric motor 9
rotates to rotate the shaft 6 clockwise 4b'. Then, the elastic members on the +Wj side and the rear side are rotated 45 degrees clockwise with respect to each link together with the shaft 6, and the elastic members on the +Wj side and the rear side are rotated 45 degrees clockwise with respect to each link, and as shown in Fig. The elastic members 7a and 7a' have a low spring constant, and the rear elastic member 7
b, 7b" are in a state of high spring constant. In this state, the elastic members 7a, 7a" and 7b, 7b' (7
) The amount of deflection is larger in the front elastic members 7a, 7a' than in the rear elastic members 7b, 7b', and the outer ring undergoes a toe-in change and the inner ring undergoes a toe-out change.

In general, in automobiles whose rear wheels are driving wheels, turning during acceleration tends to oversteer, that is, the turning radius tends to gradually become smaller, which is dangerous.

Therefore, in a rear-wheel drive vehicle, as mentioned above, in the acceleration state, the front elastic member has a low spring constant and the rear elastic member has a high spring constant in response to lateral force, by rotating and displacing the elastic member 7. When the outer wheel of the rear wheel is toe-in,
The inner wheel undergoes a toe-out change, and the rear wheel 1.1 is slightly steered in the same direction as the front wheel, so that this change in the toe angle of the rear wheel 1.1 corrects the above-mentioned oversteer tendency. Thus, it is possible to obtain steering characteristics in which the turning radius does not change, and it is possible to accurately prevent oversteer tendencies during accelerated turns and the accompanying dangers such as occurrence of crashes.

From Naoki! In J1, when the controller 20 detects an accelerated turning state by adding a turning signal from a steering angle sensor, a lateral acceleration sensor, a yaw rate sensor, etc. to an acceleration signal from the two acceleration sensors 19 as an information signal input manually to the controller 20. Alternatively, an output signal may be issued to rotate the elastic member 7 from the state shown in FIG. 4(a) to the state shown in FIG. 4(o).

In addition to the acceleration sensor 19, a vehicle speed sensor is provided to detect the vehicle speed and input the vehicle speed signal to the controller 20, and during steady driving other than during acceleration, the combination of spring constants of the rear elastic member 7 is adjusted according to the vehicle speed. It can also be changed.

An example thereof will be explained with reference to FIG.

That is, when traveling at low speed, as shown in FIG. 5(a), the front elastic members 7a, 7 are
a' has a high spring constant, and the rear elastic members 7b and 7b'' have a low spring constant. The rear elastic members 7b, 7b'' are made larger than the rear elastic members 7a, 7a''.Then, when turning, the toe angle changes so that the outer wheel is toe-out and the inner wheel is toe-in.This is due to the steering direction of the front wheels. Since the rear wheels are steered in the opposite direction, the turning performance becomes good, and the most preferable characteristics can be obtained, for example, when turning at low speed when parking the vehicle.

When running at medium speed, the elastic member 7 is rotated 45 degrees clockwise from the state shown in FIG. A constant is maintained so that the amount of deflection due to cornering force is the same for both the front and rear elastic members. In this state, there is no toe angle change due to cornering force, and it is possible to improve maneuverability at medium speeds.

During high-speed driving, the elastic member 7 is further rotated by 45 degrees clockwise from the state shown in FIG. has a low spring constant, and the rear elastic members 7b, 7b'' have a high spring constant.

In this state, the amount of deflection of the elastic member due to the cornering force is larger on the front side than on the rear side, as in the case of the acceleration turning, and the toe angle changes to the outer ring in toe-in and the inner ring toe-out. This means that the rear wheels are steered in the same direction as the front wheels, so stability during high-speed driving can be significantly improved.

As described above, it is possible to control the most preferable characteristics in each vehicle speed range.

In the illustrated embodiment, both the front elastic member and the rear elastic member are rotated by the electric motor 9 to change the spring constants of all the elastic members. One of the members, for example, the rear elastic member, is set to an intermediate or high spring constant where the spring constant does not change, and the other member, for example, is configured so that only the front elastic member is rotated by the rotation of the electric motor 9, and when accelerating, the front elastic member is set to an intermediate or high spring constant. The member may have a low spring constant in the left-right direction, and the front elastic member may have an intermediate or high spring constant in the left-right direction during steady running other than during acceleration, or may have a low spring constant during high-speed running.

Also, as an actuator for rotationally displacing an elastic member,
In addition to the electric motor, any hydraulic or vacuum type actuator may be used.

Effects of the Invention According to the present invention configured as described above, in a rear wheel drive automobile that enjoys a parallel link type rear suspension, the elastic member interposed in each attachment support portion of the front and rear links to the vehicle body member is provided. at least one elastic member of
Link hl'! The structure has a structure in which the spring constant in the direction of load input from the link changes by rotating around the center of motion, and the elastic member is rotationally displaced relative to the link during acceleration, so that the rear wheels rotate against the front wheels during acceleration and turning. By making the toe angle change in the same direction as the rudder direction, the oversteer tendency, that is, the tendency for the turning radius to become smaller during acceleration turns, is canceled out and the turning radius does not change due to changes in the toe angle of the rear wheels. This can improve maneuverability and improve safety.

In addition, in the present invention, one elastic member has a directionality of a spring constant,
The spring constant for the main load can be arbitrarily changed and set by simply rotating the elastic member, so the overall structure is extremely simple, or the spring constant can be accurately controlled, and the elastic It is possible to maintain the desired performance for a long period of time without reducing the life of the member, and since the suspension load does not directly act on the means for rotationally displacing the elastic member, in the unlikely event that the actuator or Even if there is a failure in the rotation transmission mechanism from the actuator to the elastic member and the elastic member cannot be rotated, there is almost no problem with the driving function and it is extremely desirable from a safety perspective. It can have an effect.

[Brief explanation of drawings]

Figures 1 (4) and (0) are side explanatory views and front explanatory views showing embodiments of the present invention, and Figures 2 (4) and (■) are structural examples of elastic members used in the present invention. 3(a) and 3(o) are a cross-sectional plan view and a front view showing a specific structural example of the attachment support portion of the link to the vehicle body side member in FIG. 1, respectively, and FIG. 4(4) is a front view shown in FIG. , (α) and Fig. 5 (
stomach). (a) and (c) are front views showing examples of rotation control modes of four elastic members on the front left and right and the rear left and right, which are interposed in the attachment support portion of the link to the vehicle body side member; Figure 4 (a),
(a) is an example of MI mode according to acceleration, Fig. 5 (4)
, (a) and (c) respectively show examples of control modes depending on the vehicle speed. DESCRIPTION OF SYMBOLS 1... Rear wheel, 2.3... Link, 5... Heavy body side member, 6... Shaft, 7... Elastic member, 9... Hair movement motor, 19... Acceleration sensor , 20...controller. From E

Claims (2)

[Claims] (1) In a rear-wheel drive vehicle equipped with a parallel link rear suspension in which the front and rear links that support the rear wheels are respectively attached and supported via elastic members to the vehicle body side members so as to be able to swing up and down. , at least one of the front and rear elastic members interposed in the attachment support portion of each of the front and rear links to the vehicle body side member is rotated around the swing center line of the link. The structure is configured such that the spring constant in the load input direction of the link changes when the link is moved, and the elastic member is rotationally displaced relative to the link in accordance with the acceleration during acceleration traveling to increase the rear elasticity in the load input direction of the link. A rear suspension for an automobile, comprising an actuator that causes a spring constant of a front elastic member to be lower than a spring constant of the member. (2) In a rear-wheel drive vehicle equipped with a parallel link rear suspension in which the front and rear links that support the rear wheels are each attached to a vehicle body member via an elastic member so as to be able to swing up and down. , the front and rear elastic members, each with a high spring constant in one direction and a low spring constant in the direction orthogonal to the shaft rotatably attached to the vehicle body side member, are 90° out of phase with each other. The base ends of the front and rear links are fitted onto the outer peripheries of the front and rear elastic members so as to be relatively rotatable, and the shafts are rotated in accordance with the acceleration of the vehicle. An actuator is provided, and when the actuator operates, the shaft and the front and rear elastic members fixed to the shaft rotate, and the front elastic member lowers the spring constant of the elastic member in the direction of load input from the link during acceleration traveling. A rear suspension for a vehicle, characterized in that the side elastic members are raised high.