JPS6250321B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rear suspension that rotatably supports a rear wheel of an automobile and also alleviates vibrations and shocks transmitted from the rear wheel.

(Prior Art) There are several types of automobile suspensions, one of which is a trailing arm suspension. Trailing arm type suspensions have advantages such as no change in tread or camber, a simple structure that takes up less space, and less shock when overcoming obstacles, and are mainly used for rear suspensions. It should be noted that trailing arm type suspensions are rarely used as front suspensions because the caster changes are large and the nose dive during braking is large.

In a trailing arm type rear suspension, the lateral load on the tires is supported by the trailing arm, so it is necessary to increase the lateral rigidity of the trailing arm, so it is necessary to increase the arm span and strengthen the arm. etc., making the arm itself heavier cannot be avoided. If the arm weight increases, the vehicle weight will increase,
As a result, there are problems in that fuel efficiency deteriorates and manufacturing costs increase.

In order to improve such problems, for example,
As disclosed in No. 56-62205, a suspension structure has been proposed in which a lightweight swing arm arranged in the longitudinal direction of the vehicle body is supported by two links to reduce weight and increase lateral rigidity. There is.

Such a suspension has the advantage that the camber angle can be easily adjusted by adjusting the attachment positions of the inner ends of the upper lateral link and the lower lateral link to the vehicle body. However, when the wheel moves up and down with respect to the vehicle body, that is, during bumps and rebounds, the center of the wheel is supported by the upper and lower lateral links and traces a nearly circular trajectory. Therefore, the center of the wheel moves up and down relative to the car body, and also inside the car body (in the width direction of the car body, in the direction where the lateral link is provided to the wheel, that is, the left side for the right wheel, and the right side for the left wheel). ). When the center of the wheel moves inward to the vehicle body, the other end of the swing arm on which the wheel is supported rotates inward to the vehicle body, and accordingly, the wheel faces in the toe-out direction.

In this way, the above-mentioned suspension using one swing arm and two lateral links has the advantage of increasing lateral rigidity, reducing weight, and facilitating cab control. However, there is a problem in that it is not possible to control the toe change of the tire during bumps and rebounds, and the wheel changes to the toe-out side during bumps and rebounds while driving, making the running of the vehicle unstable.

On the other hand, in contrast, West German published patent No. 2038880
The publication describes a triangular upper arm disposed above and two parallel arms disposed below.
A structure in which the wheels are supported by the lower arm of the book is disclosed. Regarding this one,
Since the attitude of the wheels is basically regulated by these three arms, by selecting the position, arrangement, and length relationship of these arms, the position of the wheels relative to the vehicle body can be adjusted in the vertical direction. This makes it possible to appropriately set the toe of the wheel even when the vehicle is in motion, and as compared to the structure of the prior art described above, the running stability due to toe change can be improved. However, since the upper arm of this publication is composed of a triangular arm with two pivot points to the vehicle body separated in the longitudinal direction,
This is particularly disadvantageous in terms of both space and riding comfort. In other words, it is necessary to secure a large space in order to allow the triangular upper arm to swing as the wheel moves up and down. Generally, the space behind the wheels is extremely limited due to the need to install other suspension components such as stabilizers, so the swinging space for the triangular arm must be secured to avoid interference with other components. Therefore, many constraints arise, and the degree of freedom in design is considerably restricted. Furthermore, while driving, impact loads are applied to the wheels in the front and rear directions due to the undulations of the road surface. Then,
The shock is easily transmitted to the vehicle body, resulting in poor ride comfort. 2
It is possible to alleviate this impact by making the elastic bushings of the point joints softer, but if they are made too soft, the camber changes ( (in the forward direction) becomes large, resulting in a decrease in grip force and worsening of steering stability.

Also, the rear end of the trailing arm in this publication is
For wheel support members that rotatably support wheels,
They are connected so that they can rotate freely. Then,
In order to enable smooth vertical movement of the wheel, it is essential to make the circumferential movement of this part smooth, and in order to ensure reliability, it is actually necessary to separately install parts such as large seal boots. As a result, there is a concern that the structure will become more complex.

(Objective of the Invention) The present invention has three lateral links added to the swing arm that extends in the front-rear direction and supports the rear wheel support, so that the outer rear wheel can be moved to the toe-out side when bumping without impairing riding comfort. The basic purpose is to prevent toe changes. A further important object of the present invention is to actively change the toe of the outer rear wheel toward the toe-in side during turning by utilizing the lateral force applied to the rear wheel.

(Structure of the Invention) The rear suspension of an automobile according to the present invention includes a rear wheel support that supports a rear wheel, a swing arm arranged in the longitudinal direction of the vehicle body, and three lateral links arranged in the lateral direction of the vehicle body. It is equipped with The swing arm is attached to the vehicle body at one point at its base end so that it can swing vertically, supports a rear wheel support at its tip, and connects this rear wheel support to the vehicle body in a manner that allows for lateral displacement. Receives rotational force and longitudinal force from the rear wheel. The three lateral links are rotatably attached at their outer ends to three mutually spaced points on the rear wheel support and at their respective inner ends to three mutually spaced points on the vehicle body through one pivoting means. At least one connecting portion at both the inner and outer ends of each lateral link is constituted by a rubber bush.

The elastic center of the lateral force on the rear wheel, which is determined by the rubber bushings of these three lateral links, is set at a position rearward of the lateral force input point to the rear wheel, so that when the lateral force is input, the center of elasticity is The wheel changes toe in the toe-in direction.

(Embodiment) FIGS. 1 to 3 each show the overall configuration of a rear suspension of an automobile. A rear wheel 1 is rotatably supported by a rear wheel support 2. The rear wheel support 2 is supported by a side frame 7 and a cross member 8 of the vehicle body by one swing arm 3 and three lateral links 4, 5, and 6. Furthermore, a strut 10 is interposed between the rear wheel support 2 and the suspension tower 9.

The swing arm 3 is a thin plate that is arranged long in the front and back direction with the plate surface in the vertical direction, and the base end (front end)
It is connected to the side frame 7 at one point so as to be able to swing up and down, and supports the rear wheel support 2 at its tip (rear end). The connecting portion on the base end side of the swing arm 3 is constituted by a rubber bush 11 whose axial direction is substantially transverse to the vehicle body. This rubber bush 11
The shaft portion is supported by a bracket 12 fixed to the lower surface of the side frame 7. Therefore, the rear wheel support 2 is connected to the thin plate swing arm 3.
Lateral displacement with respect to the vehicle body is permitted by the lateral flexural deformation of the rubber bush 11 and the deformation of the rubber bush 11.

On the other hand, the three lateral links are composed of a first lateral link 4, a second lateral link 5, arranged above and below, and a third lateral link 6, arranged on the front side. ing. The first lateral link 4 provided on the upper side is connected at its outer end to the rear upper position of the rear wheel support 2 and at its inner end to the upper position of the cross member 8 by rubber bushes 13 and 14, respectively, so as to be vertically swingable. The second lateral link 5 provided on the lower side is connected at its outer end to the rear lower position of the rear wheel support 2 and its inner end to the lower position of the cross member 8 by rubber bushes 15 and 16, respectively, so as to be able to swing up and down. . Furthermore, the third lateral link 6 provided on the front side is connected to the first and second lateral links 4,
5, and its outer end is connected to a lower front position of the rear wheel support 2, and its inner end is connected to a bracket 19 of a side frame 7 extending forward of the cross member 8 by rubber bushes 17 and 18, respectively.

In other words, the three lateral links 4 to 6 have their outer ends connected to three points on the rear wheel support 2 that form the vertices of a triangle that are spaced apart from each other, and their inner ends that connect to three points on the vehicle body that form the vertices of a triangle that are spaced apart from each other. This means that it has been done.

As shown in FIG.
(The position is indicated by a dashed line) is at a position rearward from the input point of the lateral force F to the rear wheel 1 (in the drawing, it is assumed that the lateral force is input to the center of the rear wheel 1). It is set.

The above elastic center G is the three lateral links 4~
By appropriately determining the positional relationship of the bushings 6 with respect to the rear wheel 1 and the elastic constants of the bushings 13 to 18 in the lateral direction of the vehicle body, the bushings 13 to 18 can be positioned behind the input point of the lateral force F.

Here, the position of the center of elasticity G will be discussed based on FIG. 4. In the example shown in FIG. 4, it is assumed that the connecting parts 20 to 22 on the inner end side of the three lateral links 4 to 6 are rigid (for example, ball joints are used), and the connecting parts on the outer end side uses the above-mentioned rubber bushes 13, 15, and 17, and assumes that each lateral link is rigid. Therefore, if the elastic constants of each rubber bush in the lateral direction are k ₁ , k ₂ , k ₃ and the distances from the reference line l (located in front of the rear wheel 1) are x ₁ , x ₂ , x ₃ , then The position of the center of elasticity G, that is, the distance x from the reference line l, is determined by the following equation.

x=k ₁ x ₁ +k ₂ x ₂ +k ₃ x ₃ /k ₁ +k ₂ +
k ₃ Then, assuming that the input point of the lateral force F is at the center position of the rear wheel 1 (distance x ₀ from the reference line l), the above k ₁ to k ₃ , x ₁ are set so that x > x ₀ . By setting ~ _x3 , the center of elasticity G can be located at the rear of the vehicle body relative to the lateral force input point.

Next, to explain the function of the rear suspension described above, first, when a braking force is applied to the rear wheel 1 while the car is running, the longitudinal force from the rear wheel 1 and the rotational force of the rear wheel support 2 are generated by the swing arm. 3 will take over. In addition, geometrical interference between the swing arm 3 and each lateral link 4 to 6 due to the vertical movement of the rear wheel 1,
This is absorbed by the deformation of the thin plate swing arm 3 and the deformation of each rubber bush.

However, if we look at the camber change and toe change of the rear wheel 1 when the rear wheel 1 bumps or rear bounds, the camber change will be caused by the first lateral links 4 disposed above and below.
and the second or third lateral links 5, 6 function as parallel links to prevent large ground camber changes, and each lateral link 4 to 6
Desired camber control can be performed by appropriately setting the length of .

On the other hand, regarding the toe change, in the case of this example,
The third lateral link 6 on the front side prevents the rear wheel 1 from changing to the toe-out side when bumping. Then, as shown in FIG. 5 (plan view), a lateral force F such as a cornering force acts on the rear wheel 1, but the elastic center G is located at the lateral force input point.
This _lateral force F
Therefore, for rear wheel 1, M=F(x−x ₀ )
This moment M acts on the rear wheel 1 and changes the toe-in of the rear wheel 1.

In addition, it is sufficient that at least one of the inner and outer ends of the three lateral links 4 to 6 has a connecting portion formed of a rubber bush.

Further, in the above embodiment, the strut 10 is directly attached to the rear wheel support 2, but it may be attached to either the swing arm 3 or the lateral links 4 to 6.

The rear wheel 1 can be used as a driving wheel with a configuration in which a drive shaft passes through the rear wheel support 2.

Further, in the above embodiment, the swing arm 3 acts as a trailing arm, but the base end of the swing arm is connected to the vehicle body at a position behind the rear wheel, and furthermore, the front and rear positional relationship of each lateral link is reversed, It can also be used as a leading arm.

(Effects of the Invention) According to the present invention, a longitudinal swing arm and three lateral links are provided, and the center of elasticity of the rubber bushings of the three lateral links is located rearward from the point where lateral force is input to the rear wheel. As a result, camber control is facilitated, and the toe-in of the outer wheels can be actively changed during turning by lateral force, thereby improving the stability of turning and the yawing phase delay with respect to steering.

[Brief explanation of the drawing]

The drawings illustrate an embodiment of the present invention, and FIG. 1 is a plan view of the rear suspension of an automobile with the strut omitted, FIG. 2 is a rear view of the same, FIG. 3 is a side view of the same, and FIG. 4 is an elastic center. A plan view to explain the
FIG. 5 is a plan view showing a mode of toe-in change. 1... Rear wheel, 2... Rear wheel support, 3... Swing arm, 4... First lateral link, 5... Second lateral link, 6... Third lateral link, 7... Side frame, 8 …
...Cross member, 13-18...Rubber butt.

Claims (1)

[Claims] 1. A rear wheel support that supports the rear wheel, and a rear wheel support that is attached to the vehicle body at one point at the base end so as to be able to swing up and down, and that supports the rear wheel support at the tip so as to receive rotational force and longitudinal force from the rear wheel. A swing arm arranged in the front-rear direction, each outer end pivots to three mutually distant points on the rear wheel support, and each inner end pivots to three mutually distant points on the vehicle body through one pivoting means. The wheel support includes three lateral links arranged in the lateral direction of the vehicle body that can be freely attached to the wheel support.
It is connected to the vehicle body via the swing arm so as to allow lateral displacement relative to the vehicle body, and at least one of the connecting portions at both the inner and outer ends of each lateral link is constituted by a rubber bushing. A rear suspension for an automobile, characterized in that the center of elasticity of a lateral force applied to the rear wheel determined by a rubber bushing is set at a position rearward of a lateral force input point to the rear wheel.