JPH0373482B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an automobile suspension.

(Prior art) Some automobile suspensions are
As shown in Publication No. 153422, when the lateral force acting on the rear wheel is small, the toe change of the rear wheel is zero or there is a tendency to toe-in, thereby improving straight-line stability. be.

By the way, when the above-mentioned lateral force acts strongly, such as when making a sharp turn, for example, in the case of a FF vehicle (front engine, front drive vehicle), the grip force of the front wheels, which are the driving wheels, is weakened, resulting in strong understeering characteristics. As a result, maneuverability deteriorates (the ability to follow the steering wheel becomes worse).

Therefore, if the measures described in the above-mentioned publication are applied to such FF vehicles to improve straight-line stability when lateral forces are small, the stability will increase as lateral forces increase. The understeering characteristic becomes strong, and the improvement in maneuverability becomes unsatisfactory.

On the other hand, with the aim of improving maneuverability, it is possible to make the rear wheels tend to toe out in order to weaken the understeering characteristic when lateral forces are large, but in this case, conversely, when lateral forces are small, However, there is a considerable tendency to toe out, which impairs straight-line stability.

(Objective of the Invention) The present invention was made in consideration of the above-mentioned circumstances, and aims to improve maneuverability when the lateral force increases while ensuring straight-line stability when the lateral force is small. Its purpose is to provide suspension for automobiles.

(Structure of the Invention) In order to achieve the above-mentioned object, the present invention devises the spring characteristics of at least two bushings in the suspension so that the lateral force generated on the wheel is reduced when the lateral force is small and when the lateral force is large. The behavior of toe change is changed nonlinearly.

Specifically, the configuration is as follows. That is, the rear wheels are supported by the vehicle body via a front elastic bush and a rear elastic bush that are spaced apart in the longitudinal direction of the vehicle body across the center of the rear wheels, and the lateral force input to the rear wheels causes the above-mentioned two to be In an automobile suspension in which the toe angle of the rear wheels is changed by deflecting the elastic bushings, both of the above elastic bushings are designed to bend the front elastic bushings when the lateral force input to the rear wheels is smaller than a predetermined value. The amount of deflection is set to be larger than the amount of deflection of the rear elastic bushing, and when the lateral force is larger than the above predetermined value, the amount of deflection of the rear elastic bushing is larger than the amount of deflection of the front elastic bushing. The configuration is as follows.

(Example) Fig. 1 shows an example in which the present invention is applied to the rear wheels of a FF vehicle, but since both the left and right rear wheel suspensions have the same structure, the following explanation will focus on the right rear wheel suspension. To explain about Shion,
Regarding the suspension for the left rear wheel, the suffix "L" will be used in place of the suffix "R" attached to the component for the right rear wheel, and a redundant explanation thereof will be omitted.

In FIG. 1, reference numeral 1 denotes a subframe fixed to the vehicle body as a sprung mass, and a right rear wheel 3R is attached to the subframe 1 through a swing arm type right wheel support member 2R, and a right rear wheel 3R is movable up and down. is maintained.

The wheel support member 2R includes a front lateral link 4R and a rear lateral link 5R each extending in the vehicle width direction, and a connecting link 6R serving as a wheel support member extending in the longitudinal direction of the vehicle body. The inner end (inner end in the vehicle width direction) of this front lateral link 4R is connected to a bush (elastic bush - the same below) 8 with respect to a support shaft 7R protruding from the subframe 1.
The inner end (inner end in the vehicle width direction) of the rear lateral link 5R is connected to the bush 10 with respect to the support shaft 9R protruding from the subframe 1.
They are rotatably connected via R. The outer end of the front lateral link 4R is rotatably connected via a bush 12R to a support shaft 11R protruding from the front end of the connecting link 6R, and the outer end of the rear lateral link 5R is , the bush 14 is attached to the support shaft 13R protruding from the rear end of the connecting link 6R.
They are rotatably connected via R. and,
A king pin 15R is protruded from the connecting link 6R, and the right rear wheel 3R is rotatably held around the king pin 15R.

The axes of the support shafts 7R, 9R, 11R, 13R and the bushes 8R, 10R, 12R, 14R extend in the longitudinal direction of the vehicle body. It can swing freely up and down around the center. The rear end of a tension rod 17R extending substantially in the longitudinal direction of the vehicle body is rotatably connected to a support shaft 16R protruding from the connecting link 6R via a bush 18R. It is rotatably connected to a support shaft 20R protruding from the vehicle body via a shaft 19R. Of course, both bushes 18R and 19R extend in the vehicle width direction, and the tension rod 17R supports the wheel support shaft member 2.
The rigidity of R in the front-rear direction is ensured.

The bushes 12R and 14R have different spring characteristics, and FIG. 2 shows an example of the relationship between the magnitude of the lateral force acting on the rear wheel 3R and the amount of deflection of the bushes 12R and 14R. That is,
Bush 14R located on the rear side of the vehicle body is shown in Figure 2 Y.
As shown by the line, its spring characteristics are nearly linear, while the spring characteristics of the bushing 12R located on the front side of the vehicle body are nonlinear, as shown by the X line in Figure 2. The lines X and Y intersect in the middle as shown by the intersection α. As is clear from Fig. 2, when the lateral force is small (intersection α
lateral force F (less than ₁ ), on the front bushing 12
The amount of deflection of bush R is larger than that of bush 14R on the rear side, and conversely, when the lateral force is large (intersection α
Lateral force corresponding to F (larger than ₁ ), front bushing 12R
The amount of deflection of the rear bushing 14R is smaller than that of the rear bushing 14R. Of course, the spring characteristics of the bushes 12L and 14L of the suspension for the left rear wheel are the same (the bush 12L corresponds to 12R, and the bush 14L corresponds to 14R). Note that the spring characteristics of the bushes 8R, 8L and 10R, 10L are set to be the same.

Next, a change in the behavior of the right rear wheel 3R caused by a change in the magnitude of the lateral force acting on the right rear wheel 3R due to the difference in spring characteristics between the bushes 12R and 14R described above will be explained with reference to FIG. In Fig. 3, the lateral force is indicated by F, and the attitude change of the right rear wheel 3R is shown by the solid line when the lateral force F is 0 and the dashed-double line when the lateral force F is small. The broken line indicates when F is large. Moreover, O ₁ to O ₃ are the center lines in the width direction of the right rear wheel 3R, and when O ₁ is 0 lateral force, O ₂
is shown when the lateral force is small, and O ₃ is shown when the lateral force is large. Note that the bushes 12R and 14R are each schematically shown in the shape of a spring, and in the embodiment, the dimensions of each member are set so that the lateral force F acts equally on the bushes 12R and 14R. There is.

As is clear from FIG. 3, when the lateral force F is 0, the right rear wheel 3R immediately points forward. Furthermore, when the lateral force F is small, the amount of deflection of the front bushing 12R is greater than the deflection amount of the rear bushing 14R, so the right rear wheel 3R becomes toe-in, ensuring straight-line stability. Furthermore, the lateral force F
When F is large, the amount of deflection of the rear bushing 14R is greater than the amount of deflection of the front bushing 12R, so the toe-in amount of the right rear wheel 3R is relaxed (reduced) compared to when the lateral force F is small. This will improve maneuverability. In other words, a large lateral force F is applied to the right rear wheel 3R when the steering wheel is turned to the left and the steering wheel is turned to the left, but the fact that the amount of toe-in is reduced means that understeering is more likely to occur than when the amount of toe-in is large. As the characteristics are weakened, the vehicle's ability to follow the direction of the steering wheel becomes better. Of course, all of the above applies to the left rear wheel 3L.
The same applies to

Bushing 12R having spring characteristics as described above,
Specific configuration examples of the bushings 12L, 14R, and 14L are shown in FIGS. 4 to 9. FIGS.
Figures 8 and 9 show the front bushing 12.
R, 12L is shown. These bushings 12R, 12
L, 14R, 14L are basically the support shafts 11
An inner cylinder 21 into which R, 11L or 13R, 13L is inserted, an outer cylinder 22 into which lateral links 4R, 4L or 5R, 5L are connected, and both cylinders 2.
They are common in that they have a rubber material 23 filled between 1 and 22, but they differ in details. That is, in FIGS. 4 and 5, which show examples of the rear bushings 14R and 14L, the space between the two cylinders 21 and 22 is entirely filled with the rubber material 23. In addition, the front bushing 12R,
6 and 7 showing an example of 12L, the thickness of the inner cylinder 21 is the same as that of the rear bushings 14R, 1.
It is made thicker than that of 4L, and the rubber material 23
It has two cut grooves 24 extending along the entire length in the axial direction at an interval of 180° from the axial center on the outer periphery of the axial center. Furthermore, the front side bushing 12
In FIGS. 8 and 9, which show other examples of R and 12L, there is a central space in which no rubber material 23 is present at all in the axially intermediate portion at a distance of 180° from the axial center. A synthetic material having a harder hardness than the rubber material 23 is formed in the central space 25 and is connected only to the inner cylinder 21 and at a small distance from the outer cylinder 22. A resin material 26 is interposed therebetween. Of course, bushings 12R, 12L, 14R, 14
L is not limited to the above-mentioned ones, but any suitable one can be used.

Here, the relationship between the amount of toe change of the rear wheels 3R, 3L, which changes depending on the magnitude of the lateral force F, and the improvement in straight-line stability and maneuverability will be explained with reference to FIG.
In FIG. 10, each characteristic line a to e shows how the toe changes when changing the spring characteristics of the bushes 12R, 12L and 14R, _14L . The lateral force F corresponding to the intersection α
It is the size of As is clear from Fig. 10, the ratio of the amount of toe change in the toe-in direction, which weakens the understeering characteristics, changes with the lateral force F ₁ as a boundary, and when the lateral force F is large (F ₁ When the lateral force F is larger than F1, the amount of change in the toe-in direction is made smaller than when the lateral force F is small (when it is smaller than _F1 ). Of course, any one of these characteristic lines a to e may be adopted, but for example, if characteristic line a is adopted, it places more emphasis on straight-line stability and is suitable for so-called family cars, and characteristic line e If adopted, maneuverability will be more important and it will be suitable for so-called sportakers.

Furthermore, Fig. 11 shows that depending on how the magnitude of F ₁ shown in Fig. 10 is selected, the direction followability of the vehicle relative to the steering wheel angle (shown as the magnitude of lateral acceleration in Fig. 1) can be influenced. The diagram shows how the changes occur, and the solid line in the figure indicates the conventional FF vehicle,
The dashed line and dashed line indicate the case according to the present invention. The one shown by the dashed line has F ₁ placed at point P to improve maneuverability, and the one shown by the broken line has F ₁ placed at point Q to improve maneuverability near the limit of a FF car. This is a case of doing well.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

Bush 12 as front bush and rear bush
Instead of R, 12L, 14R, 14L, bushes 8R, 8L, 10R, 10L may be selected and their spring characteristics adjusted.
2L may be selected, and bushes 10R, 10L, 14R, and 14L may be selected as the rear bushings and their spring characteristics may be adjusted.

The present invention is not limited to FF vehicles, but can be similarly applied to other types of vehicles as long as the understeering characteristics become stronger when the lateral force is large.

(Effects of the Invention) As is clear from the above description, the present invention can improve maneuverability while ensuring straight-line stability. In addition, since it is only necessary to adjust the spring characteristics of the front and rear bushings, this can be done inexpensively and easily, and in particular can be applied to existing suspensions without major design changes. be.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention. Figure 2 is a graph showing the spring characteristics of the front bushing and the rear bushing. FIG. 3 is a diagram schematically showing the operation of the present invention. FIGS. 4 to 9 are cross-sectional views showing examples of bushings used in the present invention, and FIG.
Line sectional view, Fig. 7 is Fig. 6 - line sectional view,
FIG. 9 is a sectional view taken along the line of FIG. 8. FIG. 10 is a graph showing the relationship between the magnitude of lateral force and the amount of toe change. FIG. 11 is a graph showing the relationship between steering wheel angle and lateral acceleration. 1: Subframe (vehicle body), 3R, 3L: Wheel (rear wheel), 12R, 12L: (front side) bushing,
14R, 14L: (rear side) bushings, X, Y:
Spring characteristic line.

Claims (1)

[Claims] 1. The rear wheel is supported by the vehicle body via a front elastic bushing and a rear elastic bushing that are spaced apart from each other in the longitudinal direction of the vehicle body across the center of the rear wheel, and an input signal is input to the rear wheel. In an automobile suspension in which the toe angle of the rear wheels is changed by deflecting both elastic bushes due to lateral force, both elastic bushes are configured to bend when the lateral force input to the rear wheels is smaller than a predetermined value. is set so that the amount of deflection of the front elastic bushing is greater than the amount of deflection of the rear elastic bushing, and when the lateral force is larger than the above predetermined value, the amount of deflection of the rear elastic bushing is greater than the amount of deflection of the front elastic bushing. An automobile suspension characterized by being set such that the amount of the suspension increases.