JPS62268716A - Suspension for vehicle - Google Patents

Abstract

PURPOSE:To provide an excellently accurate toe control property, by disposing rotating joints in addition to bushed between front and rear lateral links and a body for changing a ratio of a changing amount of toe in a direction to strengthening an under-steering tendency by a difference between deflection properties of the front and rear bushes. CONSTITUTION:A suspension 2R vertically movably supports a rear wheel 3R through a pair of front and rear lateral links 4R, 5R extending in a vehicle width direction. The internal ends of the respective links 4R, 5R are pivotally supported by support shaft 7R, 9R held by a sub-frame 1 through bushes 8R, 10R, wherein the internal ends of the respective links 4R, 5R are pivotally coupled with the support shafts 7R, 9R through rotating joints 28R and 29R. The respective bushes 8R, 10R are supported on a common shaft 30 and they have different deflection properties. With this arrangement, a ratio of a changing amount of toe in a direction to strengthening an under-steering tendency is made larger when lateral force is larger as compared with a case wherein the lateral force is smaller.

Description

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

(Prior Art) Recently, many automobile suspensions are designed to perform toe control of the wheels so that the vehicle body exhibits preferable behavior depending on the driving condition.

Among the devices that control the toe of the wheels, for example, in relation to the lateral force acting on the rear wheel, when the lateral force is large, compared to when it is small, the rate of change in the toe-in direction of the rear wheel due to the increase in lateral force is increased. In other words, there are some that strengthen the understeering tendency (
(See Japanese Patent Application Laid-open No. 148708/1983). In the vehicle described in the above-mentioned publication, the rear wheel is attached to the vehicle body via a pair of lateral links arranged front and rear with respect to its center of rotation so as to be movable up and down, and the rear wheels are attached to the vehicle body side or the rear wheel side of the lateral links. The above-mentioned toe control is achieved by setting the deflection characteristics of the bushing interposed in the connecting portion to be different between the front lateral link and the rear lateral link. By doing this, for example, in a car such as a FR car, where oversteering characteristics tend to become too strong when the lateral force becomes large, when the special lateral force for lane change becomes extremely large when making a sharp turn or driving at high speed. By setting the rear wheels in a relative toe-in direction, the grip force of the rear wheels is strengthened and steering stability is improved, while improving straight-line stability and maneuverability when lateral force is small, that is, at low and medium speeds. A suitable balance will be ensured.

(Problem to be solved by the invention) When the above-mentioned toe control is obtained by the difference in the deflection characteristics of the front and rear pushers, as this bush,
From the viewpoint of maintainability, etc., it is desired to utilize a bushing on the vehicle body side that is interposed at the connecting portion between each lateral link and the vehicle body side.

However, in conventional suspensions, torsional force acts on the bushings on the vehicle body side as the lateral link moves up and down, and the influence of this torsional force makes it difficult to obtain desired toe control characteristics with high accuracy. The problem arises. In other words, even if the deflection characteristics of the front and rear body-side bushings are set to obtain the desired toe control characteristics, if a torsional force is applied to the body-side bushings, the relationship between the amount of deflection and the lateral force will be distorted. It is more likely to occur.

Therefore, an object of the present invention is to develop toe control characteristics for each of the front and rear laterals such that the ratio of the amount of toe change in the direction of strengthening the understeering tendency is larger when the lateral force is large than when the lateral force is small. When obtaining the desired toe control characteristics by using front and rear bushings interposed at the connecting portion between the link and the vehicle body, the desired toe control characteristics can be achieved with high accuracy by eliminating the influence of torsional force accompanying the vertical movement of the lateral link on each bushing. The purpose of the present invention is to provide an automobile suspension that can be obtained.

(Means and operations for solving the problem) In order to achieve the above-mentioned object, in the present invention, a rotation joint is interposed between each of the front and rear lateral links and the vehicle body in addition to the bushing on the vehicle body side. By absorbing the torsional force caused by the vertical movement of the lateral link by this rotary joint, this torsional force is prevented from acting on the bushing on the vehicle body side. Specifically, the wheels are held on the vehicle body via a pair of lateral links arranged in front and behind the center of rotation, allowing them to move up and down.
In an automobile suspension, a bushing is interposed between each of the lateral links to the vehicle body side, and a rotation joint is interposed between each lateral link and the vehicle body in addition to the bushing, and the lateral link is connected to the vehicle body. It is set so that no torsional force is applied to the bushing as the bushing moves up and down, and the deflection characteristics of the front and rear bushings are set to be different from each other, so that the ratio of the amount of toe change of the wheel in a direction that increases the tendency of understeering is set. However, when the lateral force is large, it becomes larger than when the lateral force is small.

(Example) Examples of the present invention will be described below based on the attached drawings.

Figure 1 shows an example in which the present invention is applied to the rear wheels of a front-wheel drive vehicle.Since both the left and right rear wheel suspensions have the same structure, the following explanation will focus on the right rear wheel suspension. 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 this 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 l via a swing arm type right suspension 2R, so that the right rear wheel 3R can freely move up and down. Retained.

The suspension 2R includes a front lateral link 4R and a rear lateral link 5R, each extending in the vehicle width direction.
It has a hub 6R as a wheel support member extending in the longitudinal direction of the vehicle body.

Inner end of this front lateral link 4R (inner end in vehicle width direction)
is rotatably connected via a rotation joint (ball joint) 28R to a support shaft 7R held on the subframe 1 by a bush 8R, as will be described later.

Similarly, the inner end (inner end in the vehicle width direction) of the rear lateral link 5R is rotatably connected via a rotation joint 29R to a support shaft 9R held on the subframe 1 by a bush lOR. has been done. Further, the outer end of the front lateral link 4H is connected to a support shaft 11 that protrudes from the front end of the hub 6R.
The outer end of the rear lateral link 5R is rotatably connected to the hub 6R via a bushing 12R, and the outer end of the rear lateral link 5R is rotatable via a bushing 14R to a support shaft 13R protruding from the rear end of the hub 6R. is connected to. A spindle 15R is protruded from the outer end of the hub 6R, and the right rear wheel 3R is rotatably held around the spindle 15R.

The front and rear lateral links 4R and 5R are arranged substantially parallel to each other, and bushes 12R and 14 at their respective outer ends are arranged substantially parallel to each other.
A spindle 15R is arranged at an intermediate portion between the spindle 15R and R in the front-rear direction. Further, the axes of the support shafts 7R19R, IIR, 13R and the bushings 8R1IOR112R114R extend in the longitudinal direction of the vehicle body, so that the right rear wheel 3R can freely swing vertically around the support shaft 7R19R. It has become. The rear end of a tension rod 17R extending in the longitudinal direction of the vehicle body is rotatably connected to a support shaft 16R protruding from the inner end of the hub 6R via a bushing 18R. The front end portion of is rotatably connected to a support shaft 2OR protruding from the vehicle body via a bushing 19R. Of course, these bushings 18R and 19R extend in the vehicle width direction, and the tension rod 17H ensures the rigidity of the Pro R in the longitudinal direction.

Note that the lower end portion of a strut 27H consisting of a hydraulic shock absorber and a coil spring is connected to the hub 6R as is known.

The details of the connecting portion of the lateral links 4R and 5R to the vehicle body side, that is, the subframe I side, will be explained with reference to FIG. First, the support shaft 7R19R for the front and rear lateral links 4R15R is shared by one common shaft 30 that passes through the subframe 1 in the front and back direction. That is, the front end of the common shaft 30 is the support shaft 7R, and the rear end of the common shaft 30 is the support shaft 9R. Further, the front and rear bushings 8R1IOR also have the same inner cylinder 21 and outer cylinder 22, and a rubber material 23 interposed between the two cylinders 21 and 22.
are interposed at large distances in the front-rear direction. The outer cylinder 22 is welded to the subframe 1, and the common shaft 30 passes through the inner cylinder 21. Furthermore, the front and rear rotation joints 28R129R are
A main body 32 that is fitted to the front and rear ends of the common shaft 30 using a pin 31 and has a spherical bulge, and a lateral link 4R15.
The fitting recess 33 is formed at the inner end of the R and is rotatably fitted into the spherical bulge of the main body 32 without play. In addition, in FIG. 5, 34 in the middle is a locking nut.

With the above configuration, each lateral link 4R15R
When the is moved up and down around the support shaft 7R19R (common shaft 30), all the torsional force accompanying this up and down movement is transferred to the rotation joint 28.
Absorbed by R129R, Bush 8R, 10R (
This torsional force does not substantially act on the rubber material 23). And Bushu 8R, IOH
Since the rubber members 23 are arranged separately and independently in the front-rear direction, the front lateral link 4R and the rear lateral link 5 are made to have different deflection characteristics.
It is possible to set the displacement difference inward in the vehicle width direction caused by the lateral force with R to be different from each other. Note that the deflection characteristics of the bushes 12R and 14R are set to be the same.

The bushing 8R and the bushing IOR have different deflection 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 bushing 8R1IOH. That is, the characteristic line F indicating the deflection characteristics of the front bushing 8R is approximately linear. In addition, the characteristic line R indicating the deflection characteristics of the rear bushing IOH shows that the deflection is large (soft) while the load is small.
, the deflection becomes smaller (harder) as the load increases, and in the example, both characteristic lines F and R change at one point, and when the load is smaller than this intersection, the amount of deflection of the front bushing 8R is equal to that of the rear bushing 10R. is made smaller than the amount of deflection,
When the load becomes larger than this intersection, the front bushing 8R
The amount of deflection is made larger than the amount of deflection of the rear bushing IOH. Incidentally, a bush having such a characteristic line F or R is disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 60-148708.
Since it is disclosed in the Japanese Patent Publication No. 1, a detailed explanation thereof will be omitted.

Characteristic line C in Figure 3 shows the relationship between the amount of toe change of the right rear wheel 3R and the magnitude of the lateral force acting on the right rear wheel 3R, which is caused by the difference in the deflection characteristics between the front and rear bushings 8R and IOR mentioned above. Typical examples of characteristic lines that can be taken by the thin invention are shown as a, b, d, and e.

The behavior change of the right rear wheel 3R based on the characteristic line C shown in FIG. 2 will be explained with reference to FIG. 4. In this Fig. 4, the lateral force is indicated by F, and the attitude change of the right rear wheel 3R is
A solid line indicates when the lateral force F is rOJ, a chain double-dot line indicates when the lateral force F is "small", and a broken line indicates when the lateral force F is "large". Further, Oi ~ 03 is the center line in the width direction of the right rear wheel 3R, and 02 is the lateral force "0" when ol is "0".
03 indicates when the lateral force is "large".

Note that each bushing 8R1IOR is schematically shown in the shape of a spring.

As is clear from FIG. 4, when the lateral force F is O, the right rear wheel 3R points straight ahead. When the lateral force F is small, the deflection amount of the front bushing 8R is smaller than the deflection amount of the rear bushing IOH, so the right rear wheel 3R tends to toe out, and straight-line stability and maneuverability are ensured in a well-balanced manner. Also, when the lateral force F is "large", the amount of deflection of the rear bushing IOH is smaller than the amount of deflection of the front bushing 8R, so the right rear wheel 3R is The amount of toe-in is also increased and the steering stability is improved.In other words, increasing the amount of toe-in means that the understeering characteristics are stronger than when the amount of toe-in is "small". . Of course, all of the above also applies to the left rear wheel 3L.

FIG. 6 shows the deflection characteristics of the front lateral link 4R system and the rear lateral link 5R system in another embodiment of the present invention. In other words, the deflection characteristics of the front lateral link 4R system including the bushing 8R112,R have one bending point α, as shown by the characteristic line F, and become hard when the load is small and soft when the load is large. It is set as follows. Further, the deflection characteristics of the rear lateral link 5R system including the bushings IOR and 14R are roughly linear as shown by the characteristic line R. Both characteristic lines F and R intersect at one point, and with this intersection as a boundary, the magnitude relationship of the deflection amounts in both characteristic lines F and R becomes opposite, as in the case of Fig. 2. ing.

Bush 8R to obtain the characteristic line F as shown in Fig. 6
An example is shown in FIG. This bushing 8R has a total of two substantially arc-shaped hollow portions at radially opposite positions of the inner cylinder 21 on the line of action of the lateral force, and the hollow portions 24
A plate 26 made of plastic, metal, etc. is press-fitted inside to apply a precompression force to the rubber material 23, and this precompression force becomes a load corresponding to α in FIG. 6. Then, on the characteristic line F, the deflection characteristics until reaching this α are:
It depends on the deflection characteristics of the bushing 12R (the bushing 14R is set to be the same as the bushing 12R).

Although the embodiments have been described above, the present invention can be similarly applied to rear-wheel drive vehicles.

Further, the present invention can be similarly applied to any appropriate type of suspension as long as it has front and rear lateral links. For example, the front and rear lateral links 4 in Fig. 1
R15R with the inner end wider than the outer end in the vehicle width direction, and an upper arm (the shape does not matter, such as a rod shape or A type) that extends further in the vehicle width direction connected to the hub 6R. The present invention can be similarly applied to a so-called double wishbone type (multi-link type). In the multi-link type mentioned above, the tension rod 17R (railing arm) that extends in the longitudinal direction of the vehicle body is made into a plate shape so that the rigidity in the vehicle width direction is small and the rigidity in the vertical direction is high. There may be.

Furthermore, the present invention can also be applied to front wheels,
In this case, the deflection characteristics of the front and rear bushings 8R and 10R may be set to have a relationship opposite to that shown in FIG. 2 or FIG. 6. Of course, in this case, the characteristic line showing the amount of change in toe of the front wheels with respect to lateral force is shaped so that it is vertically symmetrical to that in FIG.

(Effects of the Invention) As is clear from the above description, the present invention achieves two functions: achieving an appropriate balance between straight-line stability and maneuverability when lateral forces are small, and ensuring stability when lateral forces are large. In order to obtain the characteristics that satisfy the conditions, it is achieved by creating a difference in the deflection characteristics of the front and rear bushings interposed between the front and rear lateral links and the main body. Since the joint is used to prevent the torsional force caused by the vertical movement of the lateral link,
It becomes possible to easily and reliably set the desired characteristics.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of a suspension to which the present invention is applied. FIG. 2 is a graph showing an example of the deflection characteristics of the front and rear bushings on the vehicle body to obtain the characteristics shown in FIG. FIG. 3 is a graph showing an example of a characteristic line according to the present invention. FIG. 4 is a plan view showing changes in rear wheel behavior based on the characteristics of the present invention. FIG. 5 is an enlarged plan cross-sectional view showing the connecting portion between the lateral link and the vehicle body. 6 and 7 show other embodiments of the present invention, FIG. 6 is a graph corresponding to FIG. 2, and FIG. 7 is a graph corresponding to FIG. It is a sectional view showing an example of a bush. 1: Subframe 2R12L: Suspension 3R13L: Rear wheel 4R14L: Front lateral link 5R15L: Rear lateral link 6R16L: Hub 8R: Body side bushing (front) 10R: Body side bushing (rear) 15R115L Nissin spindle (center of rotation) Fig. 2 Figure 3

Claims (1)

[Claims] (1) The wheels are held vertically movably on the vehicle body via a pair of lateral links arranged in front and behind the center of rotation, and a bush is interposed at the connection portion of each lateral link to the vehicle body. In the suspension of an automobile, a rotation joint is interposed in addition to the bush between each of the lateral links and the vehicle body, and the setting is such that torsional force is not applied to the bush as the lateral link moves up and down. The deflection characteristics of the front and rear bushings are set to be different from each other, so that when the lateral force is large, the ratio of the amount of wheel toe change in the direction of increasing the understeering tendency is larger than when the lateral force is small. An automobile suspension characterized by: