JP2636272B2 - Rear suspension - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a rear suspension mounted on a vehicle, and more particularly to a rear suspension which automatically changes a toe angle of a wheel when turning.

(Related Art) In a rear suspension mounted on a vehicle, a lateral force directed toward the turning center acts on a wheel outside the turning center, particularly when the vehicle is turning, and the wheel is moved in the running direction with respect to the lateral force. In general, the toe-in is changed so as to always be directed inward to prevent oversteer and improve running stability.

This tendency is the same in a multi-link suspension which has recently been adopted because of its simple structure, high space efficiency, light weight, and good characteristics as a rear suspension, as disclosed in JP-B-58-48366 and JP-A-58-48366. 6
An example is found in JP-A-67205.

That is, the technique disclosed in Japanese Patent Publication No. 58-48366 discloses that when a rearward load is applied to a wheel (wheel) support, the rear portion of the wheel support changes outward from the vehicle body in a plan view with respect to the front portion. A wheel support that rotatably supports the rear wheel, two arms that can swing up and down and forward and backward connecting the front and rear portions of the wheel support to the inside of the vehicle body, and the wheel support or A connecting member that elastically connects the vicinity of the wheel support support portion of the arm to the vehicle body while allowing a slight movement in the front-rear direction of the vehicle body, the vehicle body being supported between the support points of the two arms on the wheel support side; The distance in the direction is smaller than the distance in the vehicle front-rear direction between the wheel-side support points of the two arms. When the rearward load is applied to the rear-wheel contact portion and the wheel support moves rearward, the wheel support is The rear part of the wheel support is viewed from above the body relative to the front part of the body. And is configured to be displaced outward from the vehicle body.

In the technique disclosed in Japanese Patent Application Laid-Open No. 60-67205, a holder is attached to the trailing end of a trailing arm, and the holder holds a knuckle rotatably via bearings and the like. Alternatively, the front link of two front and rear parallel links connecting the knuckle and the body frame is set to be short.

Further, Japanese Patent Application Laid-Open No. 58-188707 discloses a rear suspension component having one end rotatably supported on a vehicle body and a wheel support for rotatably supporting a wheel in order to perform toe control of the wheel at the time of turning or the like. Between the wheel suspension member and the rear suspension component.
A ball joint that swings around a point, a first elastic bush that connects between the wheel support member and the rear suspension component, and a connection between the wheel support member and the rear suspension component The ball joint is located in the fourth quadrant in horizontal-vertical coordinates based on the wheel center as viewed from the left side of the vehicle body, and the first elastic bush is located in the first quadrant in the coordinates. The technique in which the second elastic bush is located in each of the second quadrants is shown.

(Problems to be Solved by the Invention) Certainly, Japanese Patent Publication No. 58-48366 and Japanese Patent Application Laid-Open No. 60-672 are disclosed.
According to the technique described in Japanese Patent Application Publication No. 05-2005, the roll steer becomes toe-in when the wheel on the outer side of the rotation center moves to the bump side due to rolling of the vehicle body at the time of rotation of the vehicle, and the above object is achieved.

However, when the understeer is always performed as a toe-in during the turning operation of the vehicle as described above, the steering effect is poor, the driving feeling is slow, and the response of the wheel side to the steering is delayed. In addition, the maneuverability at high speeds deteriorates, which is not preferable as a sports type vehicle.

Further, according to the technique described in JP-A-58-188707, the force applied to the wheel depending on the running state of the vehicle,
That is, the rear wheel can be controlled to toe-in and toe-out according to the lateral force, braking force, engine braking force, and driving force.However, since the change in toe is constant over time regardless of the vehicle speed, the driver has a great sense of discomfort. At the same time, there are multiple mechanisms and the cost is high.

SUMMARY OF THE INVENTION In view of the above, the present invention provides a rear suspension having a simple structure that enables a rear wheel to change lightly and safely in accordance with the vehicle speed during turning of a vehicle and to smoothly turn the vehicle. is there.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a multi-link suspension for connecting between a rotating support of a rear wheel and a vehicle body. Attach the lateral links connected to the vehicle body via the elastic bushes, set the front lateral links shorter than the rear lateral links, and set the hardness of the elastic bushes of the front lateral links higher than the elastic bushes of the rear lateral links. However, when the vehicle is running in rotation, first, compliance steer occurs on the rear wheel, and then roll steer larger than the compliance steer occurs.

(Operation) At the time of turning the vehicle, first, a lateral force F toward the turning center is generated in the rear wheel 3 outside the turning center, and rolling of the vehicle body is started later.

Due to the lateral force F, the elastic bushes 7, 11 of the rear link 9 of the front and rear lateral links 8, 9 are more flexed due to low hardness, so-called compliance steer-out occurs, the wheel 3 is toe-out, and the vehicle moves in yaw motion. Which results in a sharp rise at the beginning of the turn.

Then, the rolling of the vehicle body causes a so-called roll steer, and the sinking of the vehicle body outward causes the front and rear lateral links 8, 9 to relatively rotate upward. Attachment point (axis 5 ') of the elastic bush 7 of the link 9 after the rotation locus of the attachment point (axis 5)
, The wheel 3 is toe-in.

Since the toe-in amount is larger than the toe-out amount, the vehicle normally becomes toe-in, and thereafter, the wheel 3 keeps turning safely with the toe-in.

(Example) Hereinafter, an Example is described with reference to an accompanying drawing.

In the first embodiment shown in FIGS. 1 to 3, reference numeral 1 denotes a knuckle which constitutes a rotary support of the rear wheel. Arm 4 perpendicular to axle 2
And elastic bushes are attached to shafts 5, 5 'attached to both ends.
One ends of the lateral links 8, 9 are rotatably mounted via 6, 7, respectively.

The lateral links 8, 9 extend in the left-right direction of the vehicle, of which the front link 8 is shorter than the rear link 9, and the other ends of the lateral links 8, 9 are elastic bushes 10, 11 as described above. Shaft 1 fixed to body B at the same height via
2, 12 'are mounted rotatably.

Among the elastic bushes 6, 7, 10 and 11, the elastic bushes 6 and 10 belonging to the lateral link 8 are hard and the elastic bushes 7 and 11 belonging to the lateral link 9 are the elastic bushes 6 and 10.
Each of which is softer than
Even if both 6,10 are not hard and both 7,11 are not soft, only the bushes 6,7 of the elastic bushes 6,7 and 7,1 are hard and soft, and the bushes 10,11 have the same hardness. May be.

Reference numeral 13 denotes a trailing link, one end of which is rotatably mounted on a support portion 14 provided on the lower surface of the arm portion 4, and the other end of which is rotatably mounted on a vehicle body (not shown) in front of the rear wheel 3. .

Reference numeral 15 denotes a strut spring mechanism integrated with the damper 16, which is mounted between the support member 17 attached to the upper end of the knuckle 1 and a vehicle body (not shown) thereabove. Numeral 3 rotates up and down around the elastic bushes 10 and 11 of the lateral links 8 and 9 while bending the strut spring mechanism 15 and the damper 16.

In the embodiment having the above-described configuration, when the vehicle is turned, first, a lateral force F is generated on the outer rear wheel 3 toward the turning center as shown in FIG. Rolling of the vehicle body is started.

The lateral force F causes the elastic bushings 7 and / or 11 belonging to the rear link 9 of the front and rear lateral links 8 and 9 to bend more due to softness, so-called compliance steer-out occurs, and the wheel 3 becomes toe-out, and the vehicle is yawed. Exercise results, resulting in a sharp rise at the beginning of the turn.

Then, rolling of the vehicle body causes a so-called roll steer, and by sinking to the outside of the vehicle body, as shown in FIG. Since the trajectory of the shaft 5) falls inside the trajectory of the elastic bush 7 attachment point (the shaft 5 ') of the link 9 later, the wheel 3 is toe-in.

Since the toe-in amount is larger than the toe-out amount as described later, the vehicle will normally be toe-in thereafter, and the wheel 3 will continue to turn safely with the toe-in.

This state is shown by the solid line in FIG. 4, but the actual steer obtained by combining the compliance steer and the roll steer is low, and the toe-out amount is relatively large at medium speed, and the toe-in amount is smaller than the toe-out amount. (Absolute value of course increases the toe-in amount.) However toe quantity at a high speed much greater than the toe out magnitude, also, t ₁ in also FIG transition from the toe-out to toe is a t ₂ As soon as possible. This is because the delay of the roll steer with respect to the compliance steer becomes smaller at high speeds as compared to T at low and medium speeds, that is, the roll of the vehicle body is performed earlier.

In any case, in the rear suspension of the present invention, the fourth
As shown in the figure, the roll steer amount is set to be larger than the compliance steer out amount so that the toe-in amount is larger than the toe-out amount regardless of the low speed, the medium speed, and the high speed.

FIG. 5 shows a vehicle (vehicle A) in which the steer during turning of a vehicle equipped with the rear suspension of the present invention is set such that the rear wheel is always toe-in during turning as described in the above-mentioned prior art, and a toe control. As shown in this figure, the wheels of the vehicle A are toe-in from the beginning of the turning operation, and therefore the steering is performed as before. There is no sharp rise at the beginning of the turn, resulting in a pure running feeling.

In the case of car B, the toe control mechanism causes the wheels to toe out once and then shifts to toe-in. In addition to giving a sense of discomfort, the toe-out period is long, and this tendency is mechanically almost constant irrespective of the vehicle speed.

The second embodiment shown in FIGS. 6 and 7 is basically the same as the first embodiment shown in FIGS.
3 to 3 represent the same members, but in the second embodiment, the lower end portion of the knuckle 1 is bent toward the wheel 3 and the arm portion 4 is provided here.
As described above, the lateral links 8 and 9 are attached to the opposite ends via the elastic bushes 6 and 7, respectively. When viewed from the front and rear direction of the vehicle, a line 19 passing through the mounting points (the shafts 5 and 5 ') of the elastic bushes 6 and 7 and the mounting point 18 of the upper end of the strut spring mechanism 15 to the vehicle body comes into contact with the ground at an intersection 20.
There are those decided geometry of the rear suspension to outside of the intersection point 21 where the center line of the wheel 3 is in contact with the ground only L _1.

With this configuration, the behavior of the rear wheel during turning operation of the vehicle is the same as that of the first embodiment, but when braking force acts on the wheel 3 as indicated by the black arrow during braking of the vehicle, the wheel 3 Is a small arrow (black) around the intersection 20 because the intersection 20 is outside the intersection 21
In the direction, ie, the toe-in direction. Therefore, the braking posture is stabilized, and the safety of the vehicle is ensured.

FIGS. 8 and 9 are views for explaining the braking operation of the first embodiment shown in FIGS. 1 to 3. In this case, the mounting points of the elastic bushes 6, 7 (the shaft 5) are shown. , 5 ′) and the line 19 passing through the upper end of the strut spring mechanism 15 and the point of attachment 18 to the vehicle body is such that the intersection 20 ′ where the center line of the wheel 3 contacts the ground is L ₂ inside the intersection 21 where the center line of the wheel 3 contacts the ground. The geometry of the rear suspension is determined.

Accordingly, the behavior of the rear wheel during the turning operation of the vehicle is as described above. However, at the time of braking, since the intersection point 20 'is inside the intersection point 21, the wheel 3 moves in the toe-out direction due to the braking force as shown in FIG. Rotate. Therefore, as shown in FIG. 10, when a vehicle traveling on a split road in which one side of the road surface is an ice burn (low μ) and the other is a dry road (high μ) brakes, the dry road (high μ) Since the rear wheel on the side ()) toes out as described above, it is possible to prevent the vehicle from spinning, which tends to occur due to the difference in braking force between the left and right wheels.

When a driving force (opposite to the braking force) is applied, the wheels are toe-in and the posture is stabilized, so that the vehicle can be accelerated safely.

Fig. 11 and Fig. 12 show an example of application to a double wishbone type suspension.
Of the 22, 23, the front arm 22 is shorter than the rear arm 23, and the overall hardness of the elastic bushes 24, 25 belonging to the front lower arm 22 is reduced by the overall hardness of the elastic bushes 26, 27 belonging to the rear lower arm 23. This is larger than the hardness, and its operation is the same as in the first and second embodiments.

(Effects of the Invention) As described above, the present invention relates to a multi-link suspension for connecting a rotating support of a rear wheel and a vehicle body to a vehicle body via elastic bushes at front and rear sides of the rotating support, respectively. Attach the lateral link to be connected, set the front lateral link shorter than the rear lateral link, and set the hardness of the elastic bush of the front lateral link higher than that of the rear lateral link elastic bush. First, compliance steer occurs on the rear wheel, and then roll steer larger than the compliance steer occurs.In the early stage of turning the vehicle, the rear wheel is temporarily toe-out to sharpen the rise and improve rudder effectiveness. , When entering regular operation, stable high-speed operation as toe-in In addition, since the toe change is automatically performed according to the vehicle speed, the driver does not feel uncomfortable, and the structure can be simplified and the manufacturing cost can be reduced.

[Brief description of the drawings]

1 to 3 are schematic views showing a first embodiment of the rear suspension of the present invention. FIG. 1 is a front view, FIG. 2 is a plan view, and FIG. 3 is a side view. 4 and 5 are operation views of the rear suspension of the present invention, FIGS. 6 and 7 are front and plan views showing a second embodiment of the rear suspension of the present invention, and FIGS. FIG. 10 is a front view and a plan view for explaining the operation of the first embodiment during braking, FIG. 10 is an operation diagram of a vehicle equipped with the rear suspension of the first embodiment, FIG.
The figure shows a front view and a perspective view of a wishbone type rear suspension to which the present invention is applied. 1; Knuckle, 2; Askle, 3; Rear wheel, 4; Arm, 5,5 ', 12,12'; Shaft, 6,7,10,11,24,25,26,27; Elastic bush, 8 13; trailing link, 15; strut spring mechanism, 16; damper, 20,20 ', 21; intersection, 22,23; lower link.

Claims (1)

(57) [Claims] 1. A multi-link suspension for connecting a rotating support of a rear wheel to a vehicle body, wherein a lateral link connected to the vehicle body via an elastic bush is mounted on each of a front side and a rear side of the rotating support. With
The front lateral link is shorter than the rear lateral link,
Further, the hardness of the elastic bush of the front lateral link is set higher than that of the elastic bush of the rear lateral link. When the vehicle turns, first, the compliance steer is generated on the rear wheel, and then the roll steer is larger than the compliance steer. A rear suspension characterized by the above.