JP2814483B2 - 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 toward a turning center acts on a wheel outside of the turning center, particularly when the vehicle turns, and the wheel moves in a running direction in response to the lateral force. In general, the toe-in is changed so as to always go 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, and an example thereof is disclosed in Japanese Patent Publication No. 58-48366. Can be seen. 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 vehicle body-side support points of the two arms, and when the rearward load is applied to the rear wheel contact portion and the wheel support moves rearward, the wheel support 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. Japanese Patent Application Laid-Open No. 58-188707 discloses a rear suspension component member rotatably supported at one end by a vehicle body and a wheel support member rotatably supporting a wheel in order to perform toe control of the wheel at the time of turning or the like. Between the wheel support member and the rear suspension component member.
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 two elastic bushes are respectively located in the second quadrant is shown. (Problems to be Solved by the Invention) Indeed, according to the technique described in Japanese Patent Publication No. 58-48366, when the vehicle turns, the wheel outside the turning center moves to the bump side due to the rolling of the vehicle body. Then, the roll steer becomes toe-in, and the above-mentioned object is achieved. However, when the understeer is used as a constant toe-in during turning of the vehicle as described above, the rudder does not work effectively, resulting in a dull running feeling and a delay in the response of the wheel side to the steering, particularly, Maneuverability at high speed is deteriorated, 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-out or toe-out according to the lateral force, braking force, engine braking force, and driving force.However, since the change in toe is constant with time regardless of the vehicle speed, the driver has a great sense of discomfort. In addition, the mechanism is complicated and the cost is high. SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a rear suspension having a simple structure that enables a rear wheel to change lightly and safely according to the vehicle speed when the vehicle turns, thereby enabling the vehicle to turn smoothly. (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 link connected to the vehicle body via the elastic bush, and set the mounting point of the rear lateral link to the vehicle body higher than the mounting point of the front lateral link to the vehicle body,
In addition, the hardness of the elastic bush of the front lateral link is set higher than the elastic bush of the rear lateral link, and the amount of roll steer of the rear wheel during steady turning of the vehicle is larger than the compliance steer amount of the lateral link. At the time of turning, first, compliance steer is generated on the rear wheel corresponding to the outside of the turn to make a toe-out, and then roll steer larger than the compliance steer is generated to make a toe-in. (Operation) First, when the vehicle turns, a lateral force F toward the turning center is generated at the rear wheel 3 outside the turning center, and rolling of the vehicle body is started later than this. 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. This results in a sharp rise at the beginning of the turn. Then, rolling of the vehicle body causes a so-called roll steer, and when the vehicle body sinks outward, the front and rear lateral links 8 and 9 relatively rotate upward. At this time, the elastic bush 6 of the front link 8 is attached. Since the turning locus of the point (axis 5) is inside the locus of the elastic bush 7 mounting point (axis 5 ') of the link 9 later, 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 and 9 have the same length and extend in the left-right direction of the vehicle. The other ends of the lateral links 8 and 9 are connected to the front link 9 via the elastic bushes 10 and 11 in the same manner as described above. It is rotatably mounted on shafts 12 and 12 'fixed to the vehicle body B at a higher position. 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
Both of the elastic bushes 6,10 and 7,11 are hard, only the bushes 6,7, even if both 6,10 are not hard or both 7,11 are not soft,
The bushes 10 and 11 may be soft and have the same hardness. 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 structure, when the vehicle is turning, first, a lateral force F is generated on the rear wheel 3 outside the turning center toward the turning center as shown in FIG. Is started. Due to the lateral force F, the elastic bushes 7 and / or 11 belonging to the rear link 9 of the front and rear lateral links 8 and 9 are soft and more flexed, so-called compliance steer-out occurs, the wheel 3 is toe-out, and the vehicle is yawed. Motion occurs, which results in a sharp rise in the early turn. Then, the rolling of the vehicle body causes a so-called roll steer, and the vehicle sinks to the outside of the vehicle body, as shown in FIG. ) Falls inside the trajectory of the elastic bush 7 attachment point (axis 5 ') of the link 9 later, so that the wheel 3 is toe-in. Since the toe-in amount is larger than the toe-out amount as described later, the vehicle is normally toe-in thereafter, and the wheel 3 keeps turning 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 (A) in which the steer at the time of 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 prior art.
Car) and the steer of the vehicle to be controlled (vehicle B) in comparison (only at high speed).
As can be seen from this figure, in the case of the car A, the wheels are toe-in from the beginning of the turn, so that there is no sharp rise at the beginning of the turn as described above, and the running feeling is dull. In the case of car B, the toe control mechanism allows the wheels to toe out once and then transitions to toe-in, so the sharpness at the beginning of the turn can be obtained. In addition to this, the toe-out period is long, and this tendency is almost constant irrespective of the vehicle speed due to the mechanism. 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 mounted on both ends thereof via the elastic bushes 6 and 7. 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 such a configuration, the behavior of the rear wheel during turning of the vehicle is the same as in the first embodiment, but when a braking force acts on the wheel 3 as indicated by the black arrow during vehicle control, the wheel 3 Since the intersection 20 is outside the intersection 21, the wheel 3 has a small arrow (black) around the intersection 20.
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 diagrams for explaining the operation of the first embodiment shown in FIGS. 1 to 3 at the time of control. In this case, the mounting points of the elastic bushes 6 and 7 (the shaft 5) , 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 turning of the vehicle is as described above. However, since the intersection point 20 'is inside the intersection point 21 during braking, the wheel 3 is turned in the toe-out direction by the braking force as shown in FIG. Move. 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. (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 connect,
The mounting point of the rear lateral link to the vehicle body is set higher than the mounting point of the front lateral link to the vehicle body, and the hardness of the elastic bush of the front lateral link is set higher than the elastic bush of the rear lateral link. The amount of roll steer of the rear wheel during steady turning of the vehicle is made larger than the amount of compliance steer by the lateral link, and at the time of turning of the vehicle, firstly, compliance steer occurs on the rear wheel corresponding to the outside of the turn to make a toe-out, and then Roll steer larger than compliance steer is generated and toe-in, so the rear wheel is temporarily toe-out at the beginning of turning of the vehicle to sharpen the rise, improve rudder effect, and thereafter stable to high-speed turning as toe-in Has the effect of enabling Because automatically performed depending on the vehicle speed reduction, without giving an uncomfortable feeling to the driver, it can be manufactured at low cost yet structure with easy.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 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. FIG. 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, and FIG. 10 is an operation diagram of a vehicle equipped with the rear suspension of the first embodiment. 1; Knuckle, 2; Axle, 3; Rear wheel, 4; Arm, 5,5 ', 12,12'; Shaft, 6,7,10,11 ,; Elastic bush, 8,9; Lateral link, 13 Trailing link, 15; strut spring mechanism, 16; damper, 20, 20 ', 21; intersection.

Claims (1)

(57) [Claims] In a multi-link suspension for connecting between a rotating support of a rear wheel and a vehicle body, lateral links which are connected to the vehicle body via elastic bushes are respectively mounted on a front side and a rear side of the rotating support, and a rear lateral link is provided. The mounting point on the vehicle body is higher than the mounting point of the front lateral link on the vehicle body, and the hardness of the elastic bush of the front lateral link is set higher than the elastic bush of the rear lateral link. The amount of roll steer of the rear wheel during turning is larger than the amount of compliance steer by the lateral link.At the time of turning of the vehicle, first, a compliance steer is generated on the rear wheel corresponding to the outside of the turn to make a toe-out, and then larger than the compliance steer. Roll to steer and become toe-in Rear suspension, characterized in that was.