JPH0664421A - Suspension device - Google Patents

Abstract

PURPOSE:To improve steering stability of a vehicle by arranging appropriately a virtual roll shaft of a suspension member which is set by attachment position and direction of elastic bodies for attaching a suspension member to a body, to a roll center. CONSTITUTION:A suspension member 1 which supports a wheel support member for supporting wheels rotationally, so as to rock vertically is arranged spacedly in the front and rear of a vehicle and is elastically attached to the vehicle by an elastic body 3 without anisotropy in the displacing direction. To a lateral force acting on the suspension roll center determined by suspension geometry, when the suspension member 1 is rotated about a vertual roll shaft of the suspension member 1 which runs through the elastic center of the elastic bodies 3 in the front part of the vehicle and the elastic center of the elastic bodies 3 in the rear part of the vehicle, the elastic bodies 3 are arranged in such a position that steering characteristics is understeer direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension system for a vehicle such as an automobile, and more particularly to a suspension member for swingably supporting a support member for a wheel, the suspension member being interposed by an elastic body. It is suitable for a suspension system mounted on a vehicle body.

[0002]

2. Description of the Related Art In order to automatically improve steering characteristics in accordance with an external force acting on a vehicle wheel or a vehicle body, a suspension system for a vehicle, which produces a so-called compliance toe angle change, has been developed and put into practical use. Has been done. One of such suspension devices is disclosed in Japanese Patent Application Laid-Open No. 59-1451.
There is one described in Japanese Patent Publication No.

In this suspension system, as shown in FIG. 21, a wheel supporting member (axle) 2 for rotatably supporting a wheel is attached to a suspension member 1, and the suspension member 1 has an elastic body 3 interposed therebetween. Mounted on the side. As shown in FIG. 22, each elastic body 3 is configured by interposing a rubber member 3b between an inner cylinder 3a on the vehicle body side and an outer cylinder 3c on the suspension member side. 3b, for example, in a suspension system on the rear wheel side of the vehicle, as shown in the same figure, the front side portion of the vehicle body widens downward and the rearward portion of the vehicle body widens upward.

With this elastic body 3, due to the above-mentioned vertically asymmetric structure, when the outer cylinder 3c on the suspension member side is displaced downward, it is simultaneously displaced forward on the vehicle body, and the outer cylinder 3c on the suspension member side is displaced upward. At the same time, it has the effect of displacing to the rear of the vehicle body. Therefore, in the suspension device, when a lateral force is applied to the suspension device due to the anisotropy of displacement of the elastic body 3, the suspension member rolls, and at the same time, the compliance toe angle change in the understeer direction is generated, and the vehicle is driven. Has a stabilizing effect.

[0005]

The structure of the elastic body itself in the conventional suspension system has the effect of causing the compliance toe angle change in the understeer direction as the suspension member rolls, and there is no particular problem. . On the other hand, the suspension member in the suspension device rolls around a “virtual suspension member roll axis” that is determined by the mounting position of the elastic body, the elastic direction, and the displacement direction. The virtual roll axis of the suspension member means an axis that is assumed by the elastically supported suspension member, and the lateral displacement of the suspension member does not cause roll displacement when the lateral force acting on the suspension member passes through the virtual roll axis. It can be said that it is an axis.

By appropriately disposing the virtual roll axis of this suspension member, it is possible to control the change in compliance toe angle, but this has not been taken into consideration in the conventional suspension system. Considering the virtual roll axis of this suspension member in the conventional suspension system, in the elastic body shown in FIG. 22, although there is anisotropy of the displacement of the suspension member 1 in the vehicle front-rear direction due to the roll, the displacement with respect to the lateral force. That is, there is no anisotropy of the displacement in the vehicle width direction and the vehicle vertical direction accordingly.

In such a case, as shown in FIG. 23, it can be said that the pair (set) of elastic bodies 3 provided at the front portion of the vehicle has no anisotropy in the elastic direction and the displacement direction with respect to the lateral force f. Therefore, it can be said that the virtual roll axis n of the suspension member in this suspension system is a straight line passing through the simple midpoint P of the elastic body 3 of the vehicle front group and the connection point O between the suspension member 1 and the vehicle body at the vehicle rear portion. .

Then, as shown in FIG. 22, the virtual roll axis n of the suspension member in the suspension system of this conventional example passes through a point higher than the roll center R determined from the suspension geometry. Therefore, external force (lateral force)
When f is applied to the ground contact point of the wheel, the lateral force f is input to the suspension member 1 at the height hc of the roll center R by the action of the suspension link. A moment M is generated about the axis n, and the suspension member 1 rotates about the virtual roll axis n in the direction in which the outer wheel turning side faces the vehicle downward.

Along with this, the wheels supported by the suspension member 1 also rotate in the same direction with the virtual roll axis n as the central axis, but in the case of this conventional suspension system, the virtual roll axis n is Since it is directed downward toward the front of the vehicle, this rotation changes the toe angle of the outer turning wheel toward the outer side of the vehicle and the inner turning wheel toward the inner side of the vehicle, canceling understeer or promoting oversteer. There was a problem that the steering stability was reduced.

Further, due to the rotation of the wheel around the virtual roll axis n, the camber angle of the turning outer wheel changes to the positive side, and the camber rigidity of the wheel is equivalently lowered, which also results in the vehicle. However, there was a problem that the steering stability of the vehicle deteriorated. The present invention has been developed in view of these problems, and provides a suspension device that can appropriately arrange the virtual roll shaft of the suspension member in the suspension geometry to improve the steering stability of the vehicle. The purpose is to do.

[0011]

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, the virtual roll axis of the suspension member is an elastic center of a set of elastic bodies arranged in front of the vehicle. And the elastic center of a set of elastic bodies arranged at the rear of the vehicle, the virtual roll of the suspension member is set by setting the anisotropy of displacement of these elastic bodies, the mounting position, and the orientation. It was found that the shaft can be properly arranged in the suspension geometry, and the present invention was completed based on these findings.

That is, in the suspension system according to the first aspect of the present invention, the suspension member that supports the wheel support member that rotatably supports the wheel in a vertically swingable manner is provided in front of and behind the vehicle. In a suspension system which is elastically attached to a vehicle body by an elastic body which is disposed with a gap and which has no anisotropy in the direction of displacement, with respect to a lateral force applied to a suspension roll center determined from suspension geometry, When the suspension member is rotated around the virtual roll axis of the suspension member passing through the elastic center of the elastic body of the vehicle front group and the elastic center of the elastic body of the vehicle rear group, the steering characteristic is located at a position in the understeer direction. It is characterized in that an elastic body is provided.

The suspension device according to claim 2 of the present invention is
A suspension member that supports a wheel support member that rotatably supports a wheel so that the wheel support member can swing in the vertical direction is provided with an interval in front of and behind the vehicle, and an elastic body that is anisotropic in the direction of displacement. In a suspension system that is elastically attached to a vehicle body by means of a virtual force calculated by considering the anisotropy of the elastic body of the vehicle front group, with respect to the lateral force applied to the suspension roll center determined from the suspension geometry. When the suspension member rotates about the virtual roll axis of the suspension member that passes through the elastic center and the virtual elastic center calculated in consideration of the anisotropy of the elastic body of the vehicle rear group, the steering characteristic is in the understeer direction. The elastic body is arranged at different positions or directions.

The suspension device according to claim 3 of the present invention is
When the virtual roll axis of the suspension member is directed upward toward the center of the vehicle, the elastic body is arranged at a position or orientation in which the suspension roll center is below the virtual roll axis. Is.
The suspension device according to claim 4 of the present invention is the position or orientation in which the suspension roll center is above the virtual roll axis when the virtual roll axis of the suspension member is upward in the direction away from the center of the vehicle. In addition, the elastic body is arranged.

The suspension device according to claim 5 of the present invention is
A suspension member that supports a wheel support member that rotatably supports a wheel so that the wheel support member can swing in the vertical direction is provided with an interval in front of and behind the vehicle, and an elastic body that is anisotropic in the direction of displacement. In the suspension system elastically attached to the vehicle body by taking into consideration the anisotropy of the virtual elastic center calculated in consideration of the anisotropy of the elastic body of the vehicle front group and the anisotropy of the elastic body of the vehicle rear group. The virtual roll axis of the suspension member passing through the calculated virtual elastic center is at least as large as the elastic body central axis passing through the simple center point of the elastic body of the vehicle front set and the simple center point of the elastic body of the vehicle rear set. It is characterized in that the elastic body is arranged at a position or direction that is downward in the height direction of the roll center determined from the suspension geometry.

In the present invention, by disposing an elastic body having anisotropy in the displacement direction, for example, by arranging the direction having the highest rigidity so as to be inclined at a predetermined angle in the vehicle width direction, the position of the virtual elastic center is determined. And set the height to the desired position. For example, each of the elastic bodies is provided with an inner cylinder fixed to the vehicle body side, an outer cylinder arranged on the outer peripheral side of the inner cylinder and fixed to the suspension member side, and between the outer cylinder and the inner cylinder. It is realized by forming at least one of the peripheral surfaces of the inner cylinder and the outer cylinder that face each other by inclining in the vehicle width direction.

[0017]

In the suspension system according to the first aspect of the present invention, the suspension member that supports the wheel support member that rotatably supports the wheel in a vertically swingable manner is spaced apart from the front and the rear of the vehicle. It is assumed that the elastic body is elastically attached to the vehicle body by means of an elastic body that is arranged in the direction of displacement and has no anisotropy in the direction of displacement.

When these elastic bodies have no anisotropy in the displacement direction, the elastic centers of the elastic bodies of the vehicle front group and the vehicle rear group are, for example, two elastic bodies of the vehicle front group. In the case, it becomes the middle point, and in the case of three or more, it becomes the center point thereof, so the virtual roll axis of the suspension member is constituted by a straight line passing through two elastic centers. Therefore, when a lateral force is applied to the suspension roll center determined from the suspension geometry, a moment is generated around the virtual roll axis of the suspension member, and this moment causes the suspension member to rotate.

According to the present invention, the arrangement position of the elastic body that is involved in setting the virtual roll axis of the suspension member is
When the suspension member is rotated by the moment about the virtual roll axis, the steering characteristic is set to the understeer direction, so the lateral force associated with cornering or the like causes a change in the compliance toe angle in a direction that improves steering stability. To do.

In the suspension device according to the second aspect of the present invention, the suspension member that supports the wheel support member that rotatably supports the wheel in a vertically swingable manner has a space in front of and behind the vehicle. It is premised that the elastic body is elastically attached to the vehicle body by an elastic body that is anisotropically arranged in the direction of displacement. In the case of an elastic body having anisotropy in the direction of displacement as described above, there are, for example, a direction in which displacement is easy, that is, a direction in which rigidity is low, and a direction in which displacement is difficult, that is, direction in which rigidity is high. Cross at right angles. If the direction of low rigidity is defined as the displacement direction and the direction of high rigidity is defined as the elastic direction, when the moment generated around the virtual roll axis requires positive displacement, the displacement direction of the elastic body is defined as this moment. Must match the direction of. Therefore, the elastic centers of the respective elastic bodies are located on the elastic direction (elastic axis), and the elastic centers of the elastic bodies of the vehicle front group and the vehicle rear group are elastic. It becomes the intersection of the axes.

According to the present invention, the virtual elastic center calculated in this manner by considering the anisotropy of the elastic body of the vehicle front set and the anisotropy of the elastic body of the vehicle rear set are calculated. A virtual roll axis of the suspension member is set by a straight line passing through the virtual elastic center, and the suspension member rotates about the virtual roll axis of the suspension member with respect to the lateral force applied to the suspension roll center determined from the suspension geometry. At this time, since the elastic body is arranged at the position or direction where the steering characteristic becomes the understeer direction, the lateral force associated with cornering or the like causes a change in the compliance toe angle in the direction in which the steering stability is improved.

The suspension device according to claim 3 of the present invention is premised on the case where the virtual roll axis of the suspension member is directed upward toward the center of the vehicle. This indicates a case where the virtual roll axis is front-down in the front wheel suspension system of the vehicle and the virtual roll axis is front-up in the vehicle rear wheel suspension system. In this invention,
Since the elastic body is arranged at a position or orientation in which the suspension roll center is below the virtual roll axis, the suspension member rotates downward from above on the turning outer wheel side by, for example, an external force received from the turning outer wheel. To do. At this time, since the virtual roll axis of the front wheel is lowered frontward, the turning outer wheel changes the toe angle in the toe-out direction with the rotation of the suspension member, and the rear wheel of the outer wheel swings forward and the virtual roll axis moves forward, so that the suspension member The turning outer wheel changes the toe angle in the toe-in direction with the rotation.

In this way, when the front wheel-side turning outer wheel changes in the toe-out direction and the rear-wheel-side turning outer wheel changes in the compliance toe angle in the toe-in direction, the steering characteristic changes in the understeer direction, so that the turning stability is improved. The suspension device according to claim 4 of the present invention is premised on the case where the virtual roll axis of the suspension member is directed upward in the direction away from the center of the vehicle. This is
In the front wheel suspension system of the vehicle, the virtual roll axis is forwardly upward, and in the rear wheel side suspension system of the vehicle, the virtual roll axis is frontally downward.

According to the present invention, since the elastic body is arranged at a position or orientation in which the suspension roll center is above the virtual roll axis, the suspension member is lowered on the turning outer wheel side by, for example, an external force received from the turning outer wheel. To rotate upward from. At this time, since the virtual roll axis of the front wheel is rising forward, the toe angle of the turning outer wheel changes in the toe-out direction with the rotation of the suspension member, and the rear wheel has the virtual roll axis descending front of the suspension member. The turning outer wheel changes the toe angle in the toe-in direction with the rotation.

As described above, when the front wheel-side turning outer wheel changes in the toe-out direction and the rear wheel-side turning outer wheel changes in the compliance toe angle in the toe-in direction, the steering characteristic changes in the understeer direction, so that the turning stability is improved. In the suspension device according to claim 5 of the present invention, a suspension member that supports a wheel support member that rotatably supports a wheel so as to be swingable in the vertical direction is arranged in front of and behind the vehicle with a space. It is assumed that the elastic body is elastically attached to the vehicle body by means of an elastic body that has anisotropy in the displacement direction. In this case, similar to the above, the virtual elastic centers are calculated in consideration of the anisotropy of the elastic bodies of the vehicle front group, and the virtual elastic centers of the elastic bodies of the vehicle rear group are calculated in consideration of the anisotropy of the elastic bodies. And the virtual roll axis of the suspension member must be set from these virtual elastic centers.

According to the present invention, at least the suspension has a virtual roll axis of the suspension member more than the elastic body central axis passing through the simple center point of the elastic body of the vehicle front group and the simple center point of the elastic body of the vehicle rear group. The elastic body is arranged at a position or orientation that is downward at the position of the roll center determined from the geometry. Accordingly, when the virtual roll axis of the suspension member is set higher than the roll center, the distance between the roll center and the virtual roll axis can be made shorter than the distance between the roll center and the elastic body central axis. it can. Therefore, the moment generated around the virtual roll axis can be made small with respect to the lateral force input at the height of the roll center, so that the moment of the suspension member rotating from the upper side to the lower side on the outer wheel side of turning can be reduced by this moment. Reduce the roll angle change amount,
The amount of change in the camber angle of the turning outer wheel to the positive side can be reduced, and equivalently, the decrease amount of the camber rigidity of the wheel can be suppressed and the steering stability of the vehicle can be improved.

When the virtual roll axis of the suspension member is set at the same height as the roll center, that is, when the virtual roll axis passes through the roll center, the lateral force input at the height of the roll center is applied. On the other hand, since no moment is generated around the virtual roll axis, it is possible to eliminate the change in the roll angle of the suspension member on the turning outer wheel side and further reduce the amount of change in the camber angle of the turning outer wheel to the positive side. Equivalently, the camber rigidity of the wheels is prevented from decreasing, and the steering stability of the vehicle is improved.

Further, when the virtual roll axis of the suspension member is set lower than the roll center, the moment from the lower side to the upper side on the turning outer wheel side is applied to the lateral force input at the height of the roll center. Since it can be generated around the virtual roll axis, the roll angle change on the turning outer wheel side of the suspension member can be made to act in the direction of canceling the change of the camber angle of the turning outer wheel to the positive side, and equivalently the wheel The camber rigidity is further improved, and the steering stability of the vehicle is improved.

Further, as described above, when an elastic body having anisotropy in the direction of displacement is used, the virtual elastic centers of the elastic body of the vehicle front group and the elastic body of the vehicle rear group are Since it is the intersection point of the elastic axes of the respective elastic bodies, which is the direction of high rigidity, as described in claim 6, the direction in which the elastic body has the highest rigidity is tilted in the vehicle width direction and its inclination is obtained. By setting the angle to an appropriate value, the height of each virtual elastic center, that is, the height and direction of the virtual roll axis can be adjusted, which is required to achieve the inventions according to claims 2 to 5. The respective virtual elastic centers of the elastic body of the vehicle front group and the elastic body of the vehicle rear group can be set at a desired height and orientation without changing the position of the suspension member.

To arrange the elastic body with a high rigidity in the vehicle width direction as described above, for example,
As described in claim 7, it is realized by inclining the peripheral surfaces of the inner cylinder and the outer cylinder constituting the elastic body, which face each other, in the vehicle width direction. The rubber member interposed between both cylinders is
Since the rigidity is set to be high in the direction orthogonal to the fixed peripheral surface, the elastic body has high rigidity in the direction substantially orthogonal to the inclination direction of the peripheral surface. By this, the direction in which the rigidity of the elastic body is high is set in a state of being inclined in the vehicle width direction, and by setting the peripheral surface to a predetermined inclination angle,
The inclination of the elastic body in the vehicle width direction in the direction of high rigidity is set to a desired inclination angle.

In the above case, since the peripheral surfaces of the inner cylinder and the outer cylinder facing each other are only inclined, for example, the mounting shaft and the like penetrating the central axis of the inner cylinder can be vertically moved as in the conventional case. Etc. can be left in place.

[0032]

1 shows a first embodiment of a suspension system according to the present invention, which is used as a multi-link suspension system on the rear wheel side of a vehicle. An axle 2 that rotatably supports the left and right rear wheels is supported by a suspension member 1 so as to be vertically swingable, and the suspension member 1 is attached to a vehicle body via four elastic bodies 3. Two elastic bodies 3 are provided at the front of the vehicle and two at the rear of the vehicle with a space A, B,
It is arranged at points C and D, and there is used one having no anisotropy in the direction of displacement with respect to at least the lateral force f applied to the wheel.

In this embodiment, the elastic bodies 3 provided at the points A and B correspond to the elastic bodies 3 of the vehicle front set, and the elastic bodies 3 provided at the points C and D are the vehicle rear set. Elastic body 3
Equivalent to. FIG. 2 shows the suspension member 1 and the elastic body 3.
Shows the positional relationship with. In the figure, n ⁰ is the line of intersection between the widthwise center plane of the vehicle body and the ground plane, m is the line of intersection between the plane passing through the wheel center and perpendicular to the vehicle front-rear axis, and the ground plane, and P is the left and right vehicle front assembly The midpoint of the position of the elastic body 3, Q is the midpoint of the positions of the left and right vehicle rear group elastic bodies 3, n is a straight line passing through the midpoints P and Q, and Zf ⁰ is the distance of the midpoint P from the ground surface ( Height), Zr
⁰ is the distance (height) of the midpoint Q from the ground, df is the distance from the wheel center of the midpoint P (intersection line m), and dr is the distance from the wheel center of the midpoint Q (intersection line m). . Further, R indicates a roll center determined from the suspension geometry, and h
c indicates the distance (height) from the ground surface of the roll center R.

In this embodiment, each elastic body 3 is arranged so as to satisfy the following expressions (1) and (2). Zf ⁰ > Zr ⁰ (1) (dr · Zf ⁰ + df · Zr ⁰ ) / (dr + df)> hc (2) Next, the operation of this embodiment will be described in detail with reference to FIG. 3. To do.

Since the elastic body 3 used in this embodiment has no anisotropy in the direction of displacement, the midpoint P of the elastic body 3 of the vehicle front group remains the elastic center of the suspension member 1 in front of the vehicle. Therefore, the midpoint Q of the elastic body 3 of the vehicle rear group directly becomes the elastic center of the suspension member 1 in the vehicle rear direction. The elastic center of the suspension member means a point at which the suspension member elastically rotates about the elastic center. Therefore, the virtual roll axis of the suspension member is the elastic centers P and Q.
It becomes a straight line n passing through.

From the equation (1), since the elastic center P of the elastic body 3 of the vehicle front group is higher than the elastic center Q of the elastic body 3 of the vehicle rear group, the virtual roll axis n of the suspension member 1 is A straight line rising forward in front of the vehicle. on the other hand,
The left side of the equation (2) is the height of the virtual roll axis n of the suspension member at the position of the roll center R, and the height of the virtual roll axis n at the position of the roll center R is the roll center R. Is higher than the height hc of the roll center, the virtual roll axis n passes above the roll center R. The left side of the equation (2) is obtained from a simple geometrical similar figure.

When a lateral force f acts on the ground contact point of the wheel during cornering, this lateral force f is transmitted through each suspension link and acts on the roll center R for the suspension member as shown in FIG. Lateral force f
Is replaced by. Due to the lateral force f acting on the roll center R, a moment M is generated in the suspension member 1 around the virtual roll axis n of the suspension member.

At this time, since the virtual roll axis n is higher than the roll center R and rises forward, for example, the lateral force f acting on the roll center R acts from the front to the back of the paper surface of FIG. 3, the elastic member attachment points A and C of the suspension member 1 located on the front side of the drawing in FIG. 3 are displaced downward and forward (in the direction indicated by the solid line arrow in FIG. 3). The elastic member attachment points B and D of the suspension member located on the back side of the paper are displaced upward and rearward (in the direction of the broken arrow in the figure).

Here, when the lateral force f acts from the front side to the rear side in the same figure, the wheel of the suspension member 1 which is supported on the front side of the drawing is usually a turning outer wheel.
The wheel supported in the back of the paper is the turning inner wheel. Moreover, since this suspension device is the rear suspension of the vehicle, the turning outside rear wheel changes its compliance toe angle in the toe-in direction due to the forward displacement due to the rotation of the suspension member 1 about the virtual roll axis n. As a result, the rear toe wheel in the turn changes the compliance toe angle in the toe-out direction due to the rearward displacement. Therefore, since the compliance toe angle changes so as to change the steering characteristics in the understeer direction during cornering, the steering stability of the vehicle is improved.

FIG. 4 shows a second embodiment of the present invention, which is also used as a rear wheel side suspension device of a vehicle. FIG. 4 shows the relationship between the force point (roll center) R, the elastic centers P and Q, and the virtual roll axis n, as in the operation explanatory view of FIG. The relationship between the following expressions (3) and (4) is established.

Zf ⁰ <Zr ⁰ (3) (dr · Zf ⁰ + df · Zr ⁰ ) / (dr + df) <hc (4) Among these, in the formula (3), the vehicle front group is set. Since the elastic center P of the elastic body 3 is lower than the elastic center Q of the elastic body of the vehicle rear group, the virtual roll axis n of the suspension member is a straight line that is forward and downward toward the vehicle front.

On the other hand, in the equation (4), the height of the virtual roll axis n of the suspension member at the position of the roll center R is lower than the height hc of the roll center R, so that the virtual roll axis n is of the roll center R. You will pass below. In the present embodiment, during cornering, the lateral force f transmitted to the roll center R through each suspension link causes the suspension member 1 to generate a moment M about the virtual roll axis n of the suspension member. Since n is lower than the roll center R and falls forward, for example, the roll center R
When the lateral force f that acts on the suspension member acts from the front side to the back side of the paper surface of FIG. 4, the elastic member attachment points A and C of the suspension member located on the front side of the paper surface of the drawing are downward and forward (see the same drawing). (In the direction of the solid line arrow), and the elastic member attachment points B and D of the suspension member located on the far side of the drawing in the figure.
Moves upward and backward (in the direction of the broken arrow in the figure).

At this time, among the suspension members 1, the wheel supported on the front side of the drawing in the figure is the outer turning wheel, and the wheel supported on the back side of the drawing is the inner turning wheel, which is the rear suspension of the vehicle. With the rotation of the suspension member 1 around the virtual roll axis n, a change in compliance toe angle occurs in the toe-in direction on the outer rear wheel and in the toe-out direction on the inner rear wheel, and both rear wheels exhibit steering characteristics during cornering. Since the compliance toe angle changes so as to change in the understeer direction, the steering stability of the vehicle is improved.

The above is the operation when the suspension device of the present invention is used as a suspension device for the rear wheels of a vehicle. Next, the case where the suspension device of the present invention is used as a suspension device for the front wheels of a vehicle will be described. To do. In order to improve steering stability by changing the steering characteristics in the understeer direction by changing the compliance toe angle of the left and right front wheels, it is usual to change the toe angle of the outer turning wheel in the toe-out direction and the toe-in direction of the inner turning wheel. Just do it.

Therefore, when the virtual roll axis n of the suspension member obtained in the same manner as described above falls forward,
The virtual roll axis n may be set higher than the roll center R. If this is set by a conditional expression as in the above, it is expressed by the following expressions (5) and (6). Zf ⁰ <Zr ⁰ (5) (dr · Zf ⁰ + df · Zr ⁰ ) / (dr + df)> hc (6) On the other hand, when the virtual roll axis n of the suspension member rises forward, The virtual roll axis n may be set lower than the roll center R. When this is set by a conditional expression as in the above, it is expressed by the following expressions (7) and (8).

Zf ⁰ > Zr ⁰ (7) (dr · Zf ⁰ + df · Zr ⁰ ) / (dr + df) <hc (8) Therefore, the above is applied to the front wheel side and the rear wheel side of the vehicle. If the condition is set only by the direction of the virtual roll axis n without distinction, if the virtual roll axis of the suspension member is upward toward the center of the vehicle, the position where the suspension roll center is below the virtual roll axis or If the elastic body is disposed in a direction and the virtual roll axis of the suspension member is upward in the direction away from the center of the vehicle, the elastic force is set to a position or orientation in which the suspension roll center is above the virtual roll axis. The body will be arranged.

FIG. 5 shows a third embodiment of the suspension system of the present invention, which is used as a multi-link suspension system on the rear wheel side of a vehicle. In the present embodiment, two suspension members 1 are attached to the vehicle body through elastic bodies 3 arranged at points E, F, G, and H at two intervals in front of the vehicle and two in the rear of the vehicle. However, these elastic bodies 3 are made of a rubber member having a circular cross section, and hollow portions or recesses called curls are formed at positions facing each other in the radial direction along the circumferential direction thereof. By lowering the rigidity of the part, anisotropy is provided in the direction of displacement.

In this embodiment, the rigidity in the vehicle width direction is high and the rigidity in the vehicle height direction is low as shown in FIGS.
In the direction shown in FIG. 7, that is, the elastic body 3 of the front group of vehicles has a direction in which the elastic body 3 of the rear group of vehicles has a high rigidity so that the axis in the highly rigid direction is slightly upward toward the center of the vehicle in the width direction. Is attached to the suspension member 1 so that its axis is slightly downward toward the center of the vehicle in the width direction.

Since the elastic axes of these elastic bodies 3 are both in the direction of high rigidity, the elastic center of the elastic body 3 of the vehicle front group is, as shown in FIG. As a result, the elastic center of the elastic body 3 of the vehicle rear group moves downward to Q'with respect to the simple midpoint Q of the two as shown in FIG. Therefore, in this embodiment,
The virtual roll axis n of the suspension member is a straight line passing through the elastic centers P ′ and Q ′. At this time, the height of the elastic center P ′ of the elastic body 3 of the vehicle front set from the ground surface is Z.
The height of the elastic center Q ′ of the elastic body 3 of the vehicle rear group from the ground surface is Zr.

As described above, the virtual roll axis n of the suspension member is a straight line (elastic body central axis) passing through the simple midpoint P of the elastic body 3 of the vehicle front group and the simple midpoint Q of the elastic body 3 of the vehicle rear group. ) K, it is possible to improve steering stability in the same manner as described above, focusing only on the virtual roll axis n. For example, as shown in FIG. 8, when the virtual roll axis n of the suspension member is a straight line that rises forward in the front of the vehicle, the height of the virtual roll axis n at the position of the roll center R is the roll center R. Height h
Since it may be higher than c, the conditional expressions may be set by the following expressions (9) and (10) as in the expressions (1) and (2).

Zf> Zr (9) (dr · Zf + df · Zr) / (dr + df)> hc (10) By satisfying this conditional expression, the lateral force f acting on the roll center R A moment M generated around the virtual roll axis n of the suspension member causes a change in the compliance toe angle in the toe-in direction for the outer rear wheel and in the toe-out direction for the inner rear wheel, and the steering characteristic changes in the understeer direction during cornering. The driving stability of the vehicle is improved.

At this time, for example, the height of the elastic body central axis at the position of the roll center R is higher than the height hc of the roll center R, and conversely, the elastic body central axis k moves forward due to structural restrictions of the vehicle. In the case of the downward movement, the virtual roll axis n of the suspension member can be set forward and upward depending on the setting of the elastic axis of the elastic body 3, so that the suspension characteristics are the same and the layout is less restricted. It is also possible to provide a suspension device having excellent mountability.

The conditional expressions at this time include the above-mentioned expression (9),
Equation (11) below may be added in accordance with equation (10). Zf−Zf ⁰ > Zr−Zr ⁰ (11) On the other hand, when the virtual roll axis n of the suspension member is a straight line that descends forward toward the front of the vehicle, the position of the roll center R of the virtual roll axis n. Since the height of the roll center R may be made lower than the height hc of the roll center R, the above (3)
Similar to the expressions (4), the conditional expressions may be set by the following expressions (12) and (13).

Zf <Zr (12) (dr · Zf + df · Zr) / (dr + df) <hc (13) By satisfying this conditional expression, the lateral force f acting on the roll center R A moment M generated around the virtual roll axis n of the suspension member causes a change in the compliance toe angle in the toe-in direction for the outer rear wheel and in the toe-out direction for the inner rear wheel, and the steering characteristic changes in the understeer direction during cornering. The driving stability of the vehicle is improved.

Also at this time, the height at the position of the roll center R of the elastic body central axis k is the height h of the roll center R.
When the elastic body central axis k is higher than c,
In accordance with the expressions (12) and (13), the following (14)
Expressions may be added as conditional expressions. Zf−Zf ⁰ <Zr−Zr ⁰ (14) Similarly, in the front wheel side suspension device, when the virtual roll axis n of the suspension member is a straight line rising forward in the front of the vehicle, the virtual roll is increased. The height at the position of the roll center R on the axis n is the height h of the roll center R.
Since it may be set to be lower than c, the following expressions (15) and (16) may be set as the conditional expressions in the same manner as the expressions (5) and (6).

Zf> Zr (15) (dr · Zf + df · Zr) / (dr + df) <hc (16) By satisfying this conditional expression, the lateral force f acting on the roll center R Due to the moment M generated around the virtual roll axis n of the suspension member, a change in compliance toe angle occurs in the toe-out direction for the outside front wheel and in the toe-in direction for the inside front wheel, and the steering characteristic changes in the understeer direction during cornering. The steering stability of the vehicle is improved.

Further, in order to change the setting of the elastic body central axis k in the front downward direction to the front upward direction due to layout restrictions, the following equation (17) may be added. Zf−Zf ⁰ > Zr−Zr ⁰ (17) On the other hand, when the virtual roll axis n of the suspension member is a straight line that is forward and downward toward the front of the vehicle, the position of the roll center R of the virtual roll axis n. Since the height at the roll center R may be made higher than the height hc of the roll center R, the above (7)
Similar to the expressions (8), the conditional expressions may be set by the following expressions (18) and (19).

Zf <Zr ... (18) (dr.Zf + df.Zr) / (dr + df)> hc ... (19) By satisfying this conditional expression, the lateral force f acting on the roll center R A moment M generated around the virtual roll axis n of the suspension member causes a change in the compliance toe angle in the toe-in direction for the outer rear wheel and in the toe-out direction for the inner rear wheel, and the steering characteristic changes in the understeer direction during cornering. The driving stability of the vehicle is improved.

Further, in order to change the setting of the elastic body central axis to the front downward direction due to layout restrictions, the following equation (20) may be added. Zf-Zf ⁰ <Zr-Zr ⁰ (20) FIG. 9 shows a fourth embodiment of the suspension system according to the present invention, which is used as a multi-link suspension system on the rear wheel side of a vehicle. is there.

In this embodiment, two elastic bodies 3 used in the third embodiment are provided in the front of the vehicle and two in the rear of the vehicle, similarly to the suspension system of the third embodiment. In this embodiment, the rigidity is substantially high in the width direction of the vehicle and the rigidity is low in the vertical direction of the vehicle. The direction shown in FIG. 11, that is, both the elastic bodies 3 of the vehicle front group and the elastic bodies 3 of the vehicle rear group are attached to the suspension member 1 so that the elastic shafts are slightly downward toward the center of the vehicle in the width direction. There is.

Depending on the mounting position of these elastic bodies 3 and the setting direction of the elastic shaft, the elastic center of the elastic bodies 3 of the vehicle front group is P'with respect to the simple middle point P of both as shown in FIG.
As shown in FIG. 11, the elastic center of the elastic body 3 of the vehicle rear group also moves Q ′ with respect to the simple middle point Q of both.
Will move downwards to. Therefore, as shown in FIG. 12, in this embodiment, the virtual roll axis n of the suspension member is a straight line passing through the elastic centers P ′ and Q ′, and therefore the simple middle point P of the elastic body 3 of the vehicle front group and the vehicle. It is set below the elastic body central axis k passing through the simple middle point Q of the elastic body 3 of the rear group.

As a result, the height (distance) Δh 'from the roll center R at the position of the roll center R on the virtual roll axis n of the suspension member shown in FIG.
It is smaller than the height (distance) Δh from the roll center R of the elastic body central axis k. This is set by the following expression (21) as a conditional expression. (Dr · (Zf−Zf ⁰ ) + df · (Zr−Zr ⁰ )) / (dr + df) <0 (21) However, in this embodiment, the virtual roll axis n of the suspension member is above the roll center R. The following expression (22) may be added to the conditional expression in order to pass.

(Dr · Zf + df · Zr) / (dr + df)> hc (22) By satisfying this conditional expression, as shown in FIG. 12, the lateral force f acting on the roll center R causes the suspension. A moment M that is generated around the virtual roll axis n of the member and causes the turning outer wheel side of the suspension member 1 to rotate from the upper side to the lower side is smaller than a moment that is generated around the elastic body central axis k by the lateral force f. .

Therefore, the roll angle change γ ₂ of the suspension member becomes relatively small, and the change amount γ ₁ + γ ₂ of the camber angle of the wheel in the positive direction can be made small. Therefore, the camber of the suspension system against the lateral force can be reduced. The rigidity can be equivalently increased, and the steering stability of the vehicle can be improved. Note that the camber angle change γ ₁ that occurs in this case is caused by a change in the bush used for each suspension link due to the lateral force f that acts on the ground contact point of the wheel, as shown in FIG. 13. .

FIG. 14 shows a fifth embodiment of the suspension system of the present invention, which is used as a multi-link suspension system on the rear wheel side of a vehicle. In this embodiment, each elastic body 3 arranged in the same manner as in the fourth embodiment.
The elastic centers P ′ and Q ′ of the suspension member are set lower than those of the fourth embodiment, and the virtual roll axis n of the suspension member set by passing through the two elastic centers P ′ and Q ′ is
The roll center R is passed.

Therefore, in this embodiment, in addition to the expression (21), the following expression 23 is added to the conditional expression instead of the expression (22). (Dr · Zf + df · Zr) / (dr + df) = hc (23) By satisfying this conditional expression, even if the lateral force f acts on the roll center R, as shown in FIG. No moment is generated around the member's virtual roll axis n, and the suspension member 1 changes the roll angle γ.
_{Since 2} (= 0) does not occur, the amount of change γ ₁ + γ ₂ in the positive direction of the camber angle of the wheel can be made smaller than that in the fourth embodiment, so that the equivalent camber of the suspension system can be obtained. The rigidity can be further increased, and the steering stability of the vehicle can be further improved.

Camber angle change γ that occurs in this case
_As shown in FIG. 15, ₁ is only generated by the change in the bush used in each suspension link due to the lateral force f acting on the grounding point of the wheel. FIG. 16 shows a sixth embodiment of the suspension system of the present invention, which is used as a multi-link suspension system on the rear wheel side of a vehicle.

In this embodiment, the virtual roll axis n of the suspension member, which is set from the elastic centers P'and Q'of each elastic body 3 arranged as in the fifth embodiment, is below the roll center R. It was designed to pass through. Therefore, in this embodiment, in addition to the equation (21),
The following expression (24) is added to the conditional expression instead of expressions (2) and (23).

(Dr · Zf + df · Zr) / (dr + df) <hc (24) By satisfying this conditional expression, as shown in FIG.
When the lateral force f acts on the roll center R,
Around the virtual roll axis n of the rotation member.
Generates a moment M that rotates from below to above
However, the camber angle of the turning outer wheel should be
Roll angle change γ to change in the negative direction ₂Occurs
Therefore, this roll angle change γ₂By suspension
Positive generated on the wheel due to the rigidity of the link bush
Camber angle change γ₁Changes to be canceled
However, depending on the setting, the wheels change the camber angle with respect to the vehicle body.
Can be prevented. Therefore, this implementation
In the example, it is possible to make the equivalent camber rigidity infinite.
Is.

The fourth to sixth embodiments have been described in detail with respect to the case where the suspension system of the present invention is used for the rear suspension system of a vehicle. However, it can be used for the front suspension system of a vehicle. Further, as described above, the suspension device of the present invention can be applied to both the rear suspension device and the front suspension device of a vehicle. Therefore, the suspension device may be applied to both the rear and front parts, or to only one of them. You may.

Further, in each of the above-mentioned embodiments, only the example in which the suspension device of the present invention is applied to the multi-link suspension device has been described in detail, but in the suspension device of the present invention, the suspension member is separated in the front-rear direction of the vehicle. Any suspension device can be applied as long as it is a suspension device attached to the vehicle body by three or more elastic bodies provided.

The means for improving the change in compliance toe angle are described in the first to third embodiments, and the means for improving the camber angle change are described in detail in the fourth to sixth embodiments. Can also be applied together for one suspension. Furthermore, in the above-described embodiment, only the suspension members mounted on the vehicle body side by the elastic members provided in front of the vehicle and in the rear of the vehicle are described in detail. You may arrange | position three or more in front or a vehicle rear. In this case, if the simple midpoint in the text is replaced with the simple center point, it can be applied as it is.

Further, in the above embodiments, the elastic bodies 3 having anisotropy in the direction of displacement are in a state in which each elastic body 3 has its axis of attachment to the vehicle body side and the suspension member oriented in the longitudinal direction of the vehicle body. The rigidity is set relatively high in the width direction of the vehicle body by forming the curls in the rubber member of the elastic body 3, but the invention is not limited to this and is shown in FIG. With such a structure, the rigidity in the vehicle width direction may be set high.

In the elastic body 3 shown in FIG. 18, a rubber member 7 is interposed between an inner cylinder 5 and an outer cylinder 6 which are concentrically arranged with their central axes (mounting shafts) oriented vertically. Is configured. The outer peripheral surface 5a of the inner cylinder 5 and the inner peripheral surface 6a of the outer cylinder 6 both have a shape inclined by a predetermined inclination angle θ in the vehicle width direction. In this elastic body 3, the inclination reduces the rigidity in the inclination direction, increases the rigidity in the direction substantially orthogonal to the inclination direction, and forms the elastic axis L in the orthogonal direction.

As shown in FIG. 19, this elastic body 3 is used for the purpose of lowering the hip point of the rear seat, for example.
When applied to a rear suspension device in which a straight line (elastic body central axis) k passing through the simple middle point P of the elastic body of the vehicle front group and the simple middle point Q of the elastic body of the vehicle rear group is arranged in the front lower direction, In order to change the steering characteristic during cornering in the understeer direction, as described above, it is necessary to set the virtual roll axis n of the suspension member to the front and rear direction of the vehicle as shown in FIG.

For this purpose, the elastic center P'of the elastic body of the vehicle front group is set to be high and the elastic center Q'of the elastic body of the vehicle rear group is set to be low. Therefore, as shown in FIG. An axis tilted upward with the elastic axis L of the elastic body of the vehicle front set toward the center in the vehicle width direction, and an axis tilted downward with the elastic axis L of the elastic body of the vehicle rear set toward the center in the vehicle width direction. As shown in FIG.
The six opposing peripheral surfaces 5a, 6a are formed and arranged in a structure that is inclined in the vehicle width direction at a predetermined inclination angle.

As a result, the steering characteristic during cornering changes in the understeer direction, and as shown in FIG. 19, the distance Δh ′ from the roll center R to the virtual roll axis n is the distance Δh to the elastic body central axis k. The camber rigidity of the rear wheels is improved and the steering stability of the vehicle is improved. In the above elastic body, the peripheral surfaces 5a, 6a of the inner cylinder 5 and the outer cylinder 6 facing each other are both inclined, but for example, only the outer peripheral surface 5a on the inner cylinder 5 side is inclined. For example, the elastic axis L of the elastic body may be inclined in the vehicle width direction by inclining only one peripheral surface.

[0078]

As described above, according to the suspension device according to the first to fourth aspects of the present invention, the virtual position of the suspension member set from the mounting position and orientation of the elastic body for mounting the suspension member on the vehicle body. By properly arranging the roll shaft with respect to the roll center, the change in the compliance toe angle due to the roll of the suspension member due to the input of lateral force to the wheels is set to the understeer direction of the steering characteristic of the vehicle during cornering. Therefore, the steering stability of the vehicle can be improved.

According to the suspension device of the fifth aspect of the present invention, the camber angle of the turning outer wheel during cornering is set in the positive direction by setting the virtual roll axis of the suspension member below the elastic body central axis. Since it is possible to reduce the change in the roll angle of the suspension member, it is possible to equivalently improve the camber rigidity with respect to the lateral force of the wheels and improve the steering stability of the vehicle.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of a suspension device of the present invention.

FIG. 2 is an explanatory view of a virtual roll shaft of a suspension member set by the suspension device of FIG.

FIG. 3 is a side view for explaining the operation of the virtual roll shaft of the suspension member set in FIG.

FIG. 4 is a side view for explaining the action of the virtual roll shaft of the suspension member in the second embodiment of the suspension device of the present invention.

FIG. 5 is a perspective view showing a suspension device according to a third embodiment of the present invention.

6 is a rear view illustrating an elastic center of an elastic body of a vehicle front group in the suspension system of FIG.

7 is a rear view illustrating an elastic center of an elastic body of a vehicle rear group in the suspension device of FIG.

8 is an explanatory diagram of a virtual roll shaft of a suspension member set by the suspension device of FIG.

FIG. 9 is a perspective view showing a fourth embodiment of the suspension device of the present invention.

FIG. 10 is a rear view illustrating the elastic center of the elastic body of the vehicle front group in the suspension device of FIG.

FIG. 11 is a rear view illustrating the elastic center of the elastic body of the vehicle rear group in the suspension device of FIG.

12 is an explanatory diagram of a virtual roll shaft of a suspension member set by the suspension device of FIG.

13 is a front view for explaining a change in camber angle of a turning outer wheel by the suspension device of FIG.

FIG. 14 is an explanatory diagram of a virtual roll shaft of a suspension member set by the suspension device according to the fifth embodiment of the present invention.

15 is a front view for explaining a change in camber angle of a turning outer wheel in the suspension system of FIG.

FIG. 16 is an explanatory diagram of a virtual roll shaft of a suspension member set by the suspension device according to the sixth embodiment of the present invention.

FIG. 17 is a front view illustrating a change in camber angle of a turning outer wheel in the suspension device of FIG. 16.

FIG. 18 is a sectional side view showing an elastic body having another structure in the example according to the present invention.

FIG. 19 is an explanatory diagram showing a virtual roll shaft of a suspension member set in a suspension device by an elastic body having another structure.

FIG. 20 is a rear view illustrating an elastic center of an elastic body having another structure.

FIG. 21 is a perspective view showing a conventional suspension device.

22 is a cross-sectional side view of an elastic body interposed between the vehicle body and the suspension member in the suspension device of FIG.

23 is an explanatory diagram of a virtual roll shaft of a suspension member set by the suspension device of FIG.

[Explanation of symbols]

 1 Suspension member 2 Axle 3 Elastic body 5 Inner cylinder 5a Outer peripheral surface 6 Outer cylinder 6a Inner peripheral surface 7 Rubber member A to H Connection point P, Q Simple midpoint (elastic center) P ', Q' Elastic center R Roll center f Lateral force n Virtual roll axis of suspension member M Moment L Elastic axis

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yutaka Endo, 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Hiroshi Noguchi, 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd.

Claims (7)

[Claims] 1. A suspension member, which supports a wheel supporting member that rotatably supports a wheel so as to be swingable in the vertical direction, is arranged in front of and behind the vehicle with a space and is anisotropic in the direction of displacement. In a suspension system that is elastically attached to a vehicle body by a non-compliant elastic body, the elastic center of the elastic body of the vehicle front group and the vehicle rear group are against the lateral force applied to the suspension roll center determined from the suspension geometry. The suspension is characterized in that the elastic body is arranged at a position where the steering characteristic is in the understeer direction when the suspension member rotates around the virtual roll axis of the suspension member passing through the elastic center of the elastic body of . 2. A suspension member, which supports a wheel support member that rotatably supports a wheel so as to be swingable in the vertical direction, is provided in front of and behind the vehicle with a space and is anisotropic in the direction of displacement. In a suspension system elastically attached to a vehicle body by a flexible elastic body, the anisotropy of the elastic body of the vehicle front group is considered with respect to the lateral force applied to the suspension roll center determined from the suspension geometry. When the suspension member rotates about the virtual roll axis of the suspension member passing through the virtual elastic center calculated by the above and the virtual elastic center calculated by considering the anisotropy of the elastic body of the vehicle rear group, the steering is performed. A suspension device in which the elastic body is arranged at a position or direction in which a characteristic is an understeer direction. 3. The elastic body is arranged at a position or orientation in which the suspension roll center is below the virtual roll axis when the virtual roll axis of the suspension member is upward toward the center of the vehicle. The suspension device according to claim 1 or 2, characterized in that. 4. The elastic body is arranged at a position or orientation in which the suspension roll center is above the virtual roll axis when the virtual roll axis of the suspension member is upward in the direction away from the center of the vehicle. The suspension device according to claim 1 or 2, wherein the suspension device is provided. 5. A suspension member, which supports a wheel supporting member that rotatably supports a wheel so as to be swingable in the vertical direction, is provided in front of and behind the vehicle with a space and is anisotropic in the direction of displacement. In a suspension system elastically attached to a vehicle body by a flexible elastic body, the virtual elastic center calculated in consideration of the anisotropy of the elastic body of the vehicle front group and the elastic body of the vehicle rear group are anisotropic. Of the suspension member passing through the virtual elastic center calculated in consideration of the property, the elastic body center passing through the simple center point of the elastic body of the vehicle front group and the simple center point of the elastic body of the vehicle rear group. A suspension device in which an elastic body is arranged at a position or orientation that is lower than the axis in at least the height direction of the roll center determined from the suspension geometry. 6. The elastic body having anisotropy in the displacement direction is arranged such that the direction of the highest rigidity is inclined in the vehicle width direction. The suspension device described in any of the above. 7. The inner cylinder fixed to the vehicle body side, the outer cylinder arranged on the outer peripheral side of the inner cylinder fixed to the suspension member side, and the outer cylinder and the inner cylinder, respectively. And a rubber member interposed between the inner cylinder and the outer cylinder, wherein at least one peripheral surface of the inner cylinder and the outer cylinder facing each other is inclined in the vehicle width direction. The suspension device according to claim 6.