JPH085287B2 - Car suspension - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle suspension adapted to perform wheel toe control.

(Prior Art) In recent years, in many suspensions of automobiles, it is intended to perform toe control of wheels so that a vehicle body exhibits preferable behavior according to a running state.

Among those that perform toe control of this wheel, for example, in the relationship with the lateral force acting on the rear wheels, when the lateral force is large, the rate of change in the toe-out direction of the rear wheel with the increase of the lateral force is larger than when it is small. Some of them have been made to reduce the understeering tendency (see JP-A-60-148707). In the above-mentioned publication, the rear wheel is vertically movably attached to the vehicle body through a pair of lateral links arranged in front and back with the center of rotation as a boundary, and the vehicle body side or the rear wheel side of this lateral link is attached. The toe control described above is obtained by setting the flexural characteristics of the bush interposed in the connecting portion for the front lateral link and the rear lateral link so as to be different from each other. By doing so, for example, in an automobile such as an FF vehicle, in which the understeering characteristic tends to become too strong when the lateral force becomes large, when the lateral force becomes extremely large, such as when making a sharp turn or when changing lanes at high speed. Is to make the rear wheels relatively toe-out, weakening the grip of the rear wheels and improving maneuverability, while ensuring straight running stability when the lateral force is small, that is, at low to medium speeds. become.

(Problems to be Solved by the Invention) When the toe control as described above is obtained by the difference in the bending characteristics of the front and rear bushes, this bush is used as a connecting portion between each lateral link and the vehicle body side from the viewpoint of maintainability. It is desired to utilize the vehicle body side bush interposed in the vehicle.

However, in the conventional suspension, a twisting force acts on the vehicle body side bush along with the vertical movement of the lateral link, and it becomes difficult to accurately obtain a desired toe control characteristic due to the influence of this twisting force. Causes the problem. That is, even if the flexure characteristics of the front and rear body side bushes are set so as to obtain the desired toe control characteristics, when a twisting force acts on the body side bushes, the relationship of the flexure amount with respect to the lateral force is changed. It is likely to occur.

Therefore, an object of the present invention is to provide a toe control characteristic such that the ratio of the toe change amount in the direction of strengthening the understeering tendency becomes larger when the lateral force is larger than when the lateral force is small, in each of the front and rear lateral directions. When using the front and rear bushes that are interposed in the link between the link and the vehicle body side, the desired toe control characteristics can be accurately obtained by eliminating the effect of the torsional force caused by the vertical movement of the lateral link on each bush. The object is to provide a suspension for an automobile that can be obtained.

(Means and Actions for Solving Problems) In order to achieve the above-mentioned object, in the present invention, a rotary joint is interposed between each of the front and rear lateral links and the vehicle body in addition to the bush on the vehicle body side. The torsional force caused by the vertical movement of the lateral link is absorbed by the rotary joint so that the torsional force does not act on the bush on the vehicle body side. Specifically, the wheels are vertically movably held on the vehicle body via a pair of lateral links arranged in front and back with the center of rotation as a boundary, and bushes are respectively attached to connecting portions of the respective lateral links to the vehicle body side. In an intervening vehicle suspension, a rotating joint is interposed between each lateral link and a vehicle body in addition to the bushes so that a torsional force does not act on the bushes as the lateral links move up and down. The flexure characteristics of one of the front and rear bushes, which shows the amount of flexure with respect to the lateral force from the outside in the vehicle width direction, are set depending on whether the lateral force is greater than or equal to a predetermined value. The deflection ratio of the amount of deflection with an increase in lateral force is set to be different, and the deflection characteristics of the lateral link system including the specific bush with respect to the lateral force and the other b When the lateral force is larger than the predetermined value, the lateral force is larger than the predetermined value due to the difference between the deflection characteristics of the lateral link system including the swash and the ratio of the toe change amount of the wheel in the direction that weakens the understeering tendency. It is designed to be larger than when it is small.

Embodiments Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an example in which the present invention is applied to the rear wheels of an FF vehicle, but the suspensions for the left and right rear wheels have the same structure. Therefore, in the following description, the suspension for the right rear wheel will be described. For the left rear wheel suspension, the subscript "L" is used instead of the subscript "R" attached to the components for the right rear wheel, and the duplicated description is omitted.

In FIG. 1, reference numeral 1 is a subframe fixed to the vehicle body as a sprung weight, and a right rear wheel 3R is held on the subframe 1 via a swing arm type right suspension 2R so as to be vertically movable. Has been done.

The suspension 2R includes a front lateral link 4R and a rear lateral link 5R extending in the vehicle width direction, and a hub 6R as a wheel support member extending in the vehicle front-rear direction.
And have. The inner end of the front lateral link 4R (the inner end in the vehicle width direction) is connected to the support shaft 7R held by the subframe 1 by the bush 8R via a rotary joint (ball joint) 28R as described later. Are rotatably connected. Similarly, the inner end portion (the inner end portion in the vehicle width direction) of the rear lateral link 5R is rotatably connected to the support shaft 9R held by the bush 10R on the sub-frame 1 via the rotation joint 29R. Has been done. Also, front lateral link 4R
The outer end of the support shaft 11R projecting from the front end of the hub 6R.
Rotatably connected to the rear lateral link 5R via a bush 14R with respect to a support shaft 13R projecting from the rear end of the hub 6R. It is connected. The spindle 15 is attached to the outer end of the hub 6R.
R is provided so as to project, 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 a spindle 15R is arranged in the front-rear direction intermediate portion between the bushes 12R and 14R on the outer end side thereof.
Further, the support shafts 7R, 9R, 11R, 13R and the bushes 8R, 10
The axes of R, 12R, and 14R extend in the front-rear direction of the vehicle body, respectively. Therefore, the right rear wheel 3R is vertically swingable about the support shafts 7R and 9R. A rear end of a tension rod 17R extending substantially in the vehicle front-rear direction is rotatably connected to a support shaft 16R projecting from an inner end of the hub 6R via a bush 18R, and a front end of the tension rod 17R is connected. The part is a support shaft 2 protruding from the vehicle body via the bush 19R.
It is rotatably connected to 0R. Of course, both bushes
18R and 19R extend in the vehicle width direction, and the tension rod 17R secures the rigidity of the hub 6R in the front-rear direction.

The hub 6R is connected to the lower end of a strut 27R including a hydraulic shock absorber and a coil spring, as is known.

Details of a connecting portion of the lateral links 4R and 5R to the vehicle body side, that is, the subframe 1 side will be described with reference to FIG. First, the support shafts 7R and 9R for the front and rear lateral links 4R and 5R penetrate the subframe 1 in the front-rear direction 1
It is also used by the common shaft 30 of the book. 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 7R.
9R. Further, the front and rear bushes 8R and 10R also have an inner cylinder 21 and an outer cylinder 22 in common, and a rubber material 23 interposed between the both cylinders 21 and 22 is widely spaced in the front-rear direction. It is supposed to be done. The outer cylinder 22 is welded to the sub-frame 1 so that the common shaft 30 penetrates the inner cylinder 21. Furthermore, front and rear turning joints 28R, 29R
Is a main body 32 having a spherical bulging portion fitted on the front and rear ends of the common shaft 30 using a pin 31, and a spherical bulging portion of the main body 32 formed at the inner ends of the lateral links 4R, 5R. And a fitting recess 33 that is rotatably fitted without rattling. Reference numeral 34 in FIG. 5 is a retaining nut.

With the above configuration, each lateral link 4R, 5R
When the vertical movement is performed around the support shafts 7R and 9R (common shaft 30), all the torsional forces associated with this vertical movement are the rotation joints 28R and 29R.
Is absorbed by the bushes 8R and 10R (rubber material 23 thereof), and the torsional force does not substantially act on the bushes 8R and 10R. Since the rubber members 23 of the bushes 8R and 10R are separately arranged in the front-rear direction, the flexural characteristics of the bushes 8R and 10R are different from each other. The displacement difference toward the inner side in the vehicle width direction caused by the force can be set to be different from each other. The flexural characteristics of the bushes 12R and 14R are set to be the same as each other.

The bushes 8R and 10R have different flexural characteristics, and an example of the relationship between the magnitude of the lateral force acting on the rear wheel 3R and the flexure amounts of the bushes 8R, 10R is shown in FIG. That is, the characteristic line R showing the deflection characteristic of the bush 10R on the rear side is substantially linear. Further, the characteristic line F showing the deflection characteristic of the bush 8R on the front side has a large deflection (soft) when the load is small, and a deflection (hard) when the load is large. In the embodiment, both characteristic lines F and R change at one point, and when the load is smaller than this intersection, the deflection amount of the front bush 8R is made larger than the deflection amount of the rear bush 10R, and the load is greater than this intersection point. When it becomes larger, the amount of deflection of the front bush 8R is made smaller than that of the rear bush 10R. An example of a bush having such a characteristic line F or R is
Since it is disclosed in the above-mentioned JP-A-60-148707, detailed description thereof will be omitted.

The relationship between the amount of lateral force acting on the right rear wheel 3R and the toe change amount of the right rear wheel 3R caused by the difference in the deflection characteristics of the front and rear bushes 8R and 10R is shown by the characteristic line c in FIG. In addition, representative examples of characteristic lines that can be taken in the present 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 described with reference to FIG. In Fig. 4, the lateral force is indicated by F, and the posture change of the right rear wheel 3R is shown by a solid line when the lateral force F is "0" and a two-dot chain line when the lateral force F is "small". Further, when the lateral force F is "large", it is indicated by a broken line. Further, O _{1 to} O ₃ are the center lines in the width direction of the right rear wheel 3R, and when O ₁ is the lateral force “0”, O ₂ is the lateral force “small”, and O ₃ is the lateral force. The time of "large" is shown. The bushes 8R and 10R are each schematically shown in the shape of a spring.

As is apparent from FIG. 4, when the lateral force F is 0, the right rear wheel 3R is facing straight ahead. When the lateral force F is small, the deflection amount of the front side bush 8R is larger than the deflection amount of the rear end bush 10R, so that the right rear wheel 3R tends to toe-in, and straight running stability is secured. When the lateral force F is “large”, the amount of deflection of the rear bush 10R is larger than that of the front bush 8R, so the right rear wheel 3R
Means that the toe-in amount is lessened than when the lateral force F is “small”, and the maneuverability is improved. That is, the fact that the toe-in amount is alleviated means that the understeering characteristic is weakened more than when the toe-in amount is "large", and the direction followability with respect to the notch of the steering wheel becomes good. Of course, all the above is the same for 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. That is, the bending characteristics of the rear lateral link 5R system including the bushes 10R and 14R are 1 as shown by the characteristic line R.
It has three break points α and is set to be hard when the load is small and soft when the load is large. The flexural characteristics of the front lateral link 4R system including the bushes 8R and 12R are substantially linear as shown by the characteristic line F. The characteristic lines F and R intersect at one point, and the characteristic lines F and R intersect with each other at the intersection, as in the case of FIG.
The magnitude relationship of the amount of deflection in and is reversed.

Bushing 10 for obtaining characteristic line R as shown in FIG.
An example of R is shown in FIG. The bush 10R has a total of two substantially arc-shaped hollow portions at positions radially opposite to the inner cylinder 21 on the line of action of lateral force, and a plate 26 made of plastic, metal or the like is press-fit into the hollow portion 24. Then, a precompression force is applied to the rubber material 23, and this precompression force becomes a load corresponding to α in FIG. And the characteristic line R
In this case, the flexural characteristics until reaching α depend on the flexural characteristics of the bush 14R (Bush 1
2R is set the same as 14R).

Although the embodiments have been described above, the present invention is equally applicable to rear-wheel drive vehicles.

Further, the present invention can be similarly applied to an appropriate type of suspension as long as it has front and rear lateral links. For example, the front and rear lateral links in Figure 1.
4R, 5R with the inner end in the vehicle width direction wider than the outer end, and an upper arm (rod-shaped or A-shaped such as the shape does not matter) extending further in the vehicle width direction with respect to the hub 6R. The same can be applied to a so-called double wishbone type (multi-link type) that is connected. In the above multi-link type, tension rod 17R (trailing arm) that extends in the vehicle front-rear direction
May have a plate shape so that the rigidity in the vehicle width direction is low and the rigidity in the vertical direction is high.

Further, the present invention can be applied to the front wheels as well, in which case the flexural characteristics of the front and rear bushes 8R and 10R have the opposite relationship to those shown in FIG. 2 or FIG. Just set it. Of course, in this case, the characteristic line showing the toe change amount of the front wheel with respect to the lateral force is shaped to be vertically symmetrical to that in FIG.

(Effects of the Invention) As is apparent from the above description, the present invention provides characteristics that satisfy the two conditions of ensuring straight-line stability when lateral force is small and ensuring maneuverability when lateral force is large. In order to obtain it, it is obtained by making a difference in the bending characteristics of the front and rear bushes interposed between the front and rear lateral links and the main body, while using a rotary joint for the bushes on the vehicle body side Since the torsional force associated with the vertical movement of the link is not applied, it is possible to set the desired characteristics easily and surely.

[Brief description of drawings]

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 deflection characteristics of front and rear bushes on the vehicle body side for obtaining the characteristics shown in FIG. FIG. 3 is a graph showing an example of characteristic lines according to the present invention. FIG. 4 is a plan view showing a behavior change of the rear wheel based on the characteristic according to the present invention. FIG. 5 is an enlarged plan sectional view showing a connecting portion between the lateral link and the vehicle body. FIGS. 6 and 7 show another embodiment of the present invention. FIG. 6 is a graph corresponding to FIG. 2, and FIG. 7 is a graph for obtaining the deflection characteristics as shown in FIG. 6F. It is sectional drawing which shows an example of a bush. 1: Subframe 2R, 2L: Suspension 3R, 3L: Rear wheel 4R, 4L: Front lateral link 5R, 5L: Rear lateral link 6R, 6L: Hub 8R: Body side bush (front) 10R: Body side bush (rear) 15R, 15L: Spindle (center of rotation)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-148707 (JP, A) Actually opened 61-16906 (JP, U) Actually opened 61-3005 (JP, U)

Claims (1)

[Claims] 1. A wheel is vertically movably held by a vehicle body via a pair of lateral links arranged in front and back with a center of rotation as a boundary, and bushes are respectively attached to connecting portions of the lateral links to the vehicle body side. In an intervening vehicle suspension, a rotating joint is interposed between each lateral link and a vehicle body in addition to the bushes so that a torsional force does not act on the bushes as the lateral links move up and down. The flexure characteristics of one of the front and rear bushes, which shows the amount of flexure with respect to the lateral force from the outside in the vehicle width direction, are set depending on whether the lateral force is greater than or equal to a predetermined value. The deflection ratio of the amount of deflection with an increase in lateral force is set to be different, and the deflection characteristics of the lateral link system including the specific bush with respect to the lateral force and the other b Due to the difference from the flexural characteristics of the lateral link system including the thrust, when the ratio of the toe change amount of the wheel in the direction of weakening the understeering tendency is larger than the predetermined value, the lateral force is larger than the predetermined value. An automobile suspension characterized in that it is designed to be larger than when it is small.