JPS6144687B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a rear suspension for an automobile, and more particularly to a novel rear suspension with excellent toe-in effect. BACKGROUND ART In the rear suspension of an automobile, in order to improve steering stability, riding comfort, etc., it is desired to have a rear suspension that allows tires to be toe-in during driving, especially when cornering. In other words, as is well known, when cornering, the centrifugal force applied to the vehicle body acts on the suspension as a lateral force.
In order to increase the turning limit G, it is desirable for tires to counteract this lateral force with a large resistance force. This drag can be increased by toe-in the tire and increase the slip angle. Also, if you increase this drag and improve the grip of the rear wheels, you can strengthen the tendency to understeer,
It can improve the stability of the car. moreover,
When cornering, when you press and release the accelerator, driving force and braking force are applied to the tires, but when you release the accelerator, the tires tend to suddenly toe out, and when you press the accelerator, they tend to toe in. This causes the tires to toe in or toe out during cornering, resulting in a decrease in steering stability (hereinafter referred to as steering stability). Also, when you step on the brakes or apply engine braking, the rubber bushings installed to improve riding comfort are located inside the tire's ground contact point, so the braking force can cause toe-out. This results in poor handling. The softer the rubber bushings, the better the ride quality, so the more comfortable a car is, the worse it will be in handling. Therefore, a rear suspension that provides toe-in even when braking force is applied by the brake or engine brake is desired. In other words, a rear suspension that always has a tendency to toe-in will always achieve stable cornering. In addition, the tendency of rear suspension toe-in is not limited only when cornering.
This is also desirable from the viewpoint of high-speed straight-line performance, which is particularly required for sports cars. That is, the road surface is actually not completely flat and always has irregularities of various sizes, but these irregularities cause disturbances to the tires from various directions. In addition, the wind that the car receives while driving acts as a lateral force when there is a crosswind, but even when there is no crosswind, the wind acts on the car's tires as a disturbance from all directions. Even in response to these disturbances, if the rear suspension always acts to toe-in the rear wheels, the car will tend to understeer and become stable. Regardless of the cause, these disturbances end up acting on the tires as one of the aforementioned lateral forces, braking forces, and driving forces. Therefore, the rear suspension is desired to have the effect of toe-in the tires against all of the lateral force, braking force (there are two types: braking and engine braking), and driving force. To explain these external forces in detail, the lateral force represented by the thrust load during cornering is the force that acts from the outside to the inside of the tire's grounding point, and the braking force when applying the brakes is the force that acts in front of the tire's grounding point. The force from the engine brake is the force that acts on the wheel center of the tire from front to back, and the driving force is the force that acts on the wheel center from the back to the front. This can be expressed in a table as shown below.

[Table] Various types of rear suspensions have been known that have a toe-in effect against lateral force during cornering, but all of them are structurally somewhat complex. For example, the one described in Japanese Patent Publication No. 52-37649 uses three rubber bushings and the hardness of the bushings is changed, and the one described in West German Patent Publication No. 2158931 or West German Patent Publication No. 2355954 is The wheel hub is supported via a vertical shaft and a spring, making the structure complex.
Further, this kind of rear suspension that is known in the past does not achieve toe-in effects against all of the above four types of external forces, but is mainly effective only against lateral forces. SUMMARY OF THE INVENTION An object of the present invention is to provide a novel rear suspension that has an extremely simple structure and can effectively toe-in the rear wheels against external forces, especially during cornering. Furthermore, the present invention has an extremely simple structure that enables toe-in of the rear wheels in response to any external force such as lateral force, braking force, engine braking force, or driving force, regardless of whether the vehicle is turning or going straight. The aim is to provide a completely new type of rear suspension that makes it possible to create highly safe cars. The rear suspension of the present invention connects a vehicle body side support member, which is partially connected to the vehicle body, and a rear wheel hub using one ball joint and two rubber bushes. The point is located in the first quadrant of the horizontal-vertical coordinates based on the wheel center seen from the left side of the vehicle, one of the rubber bushes is located in the fourth quadrant, and the other is located in the second quadrant. This is a characteristic feature. In the present invention, the vehicle body side support member includes, for example, the semi-trailing arm of a semi-trailing type rear suspension, the strut of a strut type rear suspension, the upper and lower arms of a cross-bond type rear suspension, and the upper and lower arms of a deion type rear suspension. This is a general term for various supporting members attached to the vehicle body side, such as the rear suspension tube, and the type of rear suspension that is the subject of the present invention includes any type of rear suspension that supports tires in a toe-in manner. It is not limited to a specific thing. Further, the quadrant defined in the present invention is a quadrant in rectangular coordinates when looking at the rear wheel from the left side of the vehicle body and assuming horizontal and vertical orthogonal axes with the wheel center as the center, and It is assumed that each quadrant includes the axes at both ends that limit the quadrant (for example, in the first quadrant, the right half of the horizontal axis and the upper half of the vertical axis). According to the rear suspension of the present invention, it is possible to effectively toe-in the tire when a lateral force is applied, and it is also possible to toe-in the tire when any of the four types of external forces are applied.
This toe-in effect is obtained by arranging the suspension ball joint and rubber bush as described above, and utilizes the deformation of the rubber bush around the vertical and horizontal axes that pass through the ball joint. By rotating the wheel hub, toe-in is achieved in response to various external forces. Hereinafter, the present invention will be explained in more detail with reference to the drawings. Figures 1 to 6 show an embodiment in which the present invention is applied to a semi-trailing type rear suspension. Figure 1 is a plan view of the right rear wheel, and Figure 2 is a view from the right side of the vehicle body. The side view and FIG. 3 are elevational views seen from the rear, with the tire portion cut away or omitted so that the suspension portion can be clearly seen. Figure 4A is A- in Figure 2.
4B is a sectional view taken along line A'-A' of FIG. 4A, FIG. 5A is a sectional view taken along line B-B of FIG.
Figure B is a sectional view taken along line B'-B' of Figure 5A, and Figure 6 is a cross-sectional view of Figure 2.
It is a sectional view taken along the line CC in the figure. Figure 2 is a side view of the vehicle body as seen from the right side.
The 2nd, 3rd, and 4th quadrants are indicated by symbols,,,. As shown in FIG. 1, the semi-trailing arm 10 consists of two arms: an inner arm 10a and an outer arm 10b.
Each branch arm 10a, 10b is swingably supported around a common swing shaft 11 by a support member on the vehicle body side.
Rear end 10c of this semi-trailing arm 10
is separated from the wheel hub 22 that fixes the wheel 21 of the tire 20, and both can be displaced with some elasticity around the ball joint 4 by two rubber bushes 1, 3 and one ball joint 4. is combined with That is, in the illustrated embodiment, three arms 2 are provided on the wheel hub 22 side.
2a, 22b, and 22c are provided (see FIGS. 2 and 3), and the tip of this arm is pivoted to three pivot supports 12a, 12b, and 12c provided at the rear end 10c of the semi-trailing arm 10. has been done. That is, the first arm 22a is elastically supported by the rubber bushing shaft support 12a located in the second quadrant and with its lower side facing inward.
2b is located in the 4th quadrant and is backward (or above)
The third arm 22c is elastically supported by the rubber bushing shaft support 12b facing outward, and the third arm 22c is
Ball joint support part 12c located in the quadrant
It is rotatably supported around one point. As shown in Figures 4A, 4B, 5A, and 5B, the rubber bushings 12a, 12b that pivotally support the first and second arms 22a, 22b cannot be displaced in the axial direction or in the direction perpendicular to the axis. However, the rubber bush 13a of the rubber bush shaft support 12a located in the second quadrant is made of a highly rigid material 13 on the outside so that it deforms only inward.
A' is inserted into the rubber bush shaft support 12b located in the fourth quadrant, and a stopper 13b' is inserted into the front side of the rubber bush 13b so as to limit forward displacement. The ball joint support part 12c that supports the third arm 22c at a point is provided with a spherical part 13c that does not allow displacement in the axial direction but only allows rotation around one point. It is supported so that it can rotate. In this way, the wheel hub 22 of the tire has two rubber bushings 12a, 12b (corresponding to the rubber bushings 1, 3) and one It is coupled elastically and movably around the ball joint 4 via two spherical portions 13c (corresponding to the ball joint 4). With support from these three points, this rear suspension has the effect of toe-in the tire against all of the lateral force S, braking force B, engine braking force E, and driving force K. Hereinafter, the principle of operation of various embodiments of the present invention including the structure of the above-described embodiments will be explained in detail with reference to FIGS. 7, 8, and 9. In FIG. 7, a perspective view of the rear right tire of the automobile viewed from the rear left is shown in the center, and projected views of this from the rear, left side, and above are shown on the left, right, and below. In the rectangular coordinates formed by the horizontal axis H and the vertical axis V, which extend in the longitudinal direction of the vehicle body, with the wheel center W as the center, the first
A ball joint 4 is arranged in the quadrant, and rubber bushes 1 and 3 are arranged in the second and fourth quadrants. In this basic arrangement, the plane formed by the ball joint 4 and the rubber bushes 1 and 3 (represented by numeral 10 in the rear projection view)
is on the outside (-) or inside (+) with respect to the wheel center W, and whether it is on the outside (-) or inside (+) with respect to the grounding point G (hereinafter referred to as offset). ), the layout types are W+G+, W+G-, W-G+, and W-G-.
Classified as a species. Among these, W+G- is particularly effective, and Fig. 7 shows an example of this W+G- (that is, the offset at the wheel center is (+) and the ground point is (-). Below, in the case of this W+G- The toe-in effect against external force is shown in detail in the drawings.The vertical imaginary axis passing through the ball joint 4 is defined as L, the lateral (parallel to the axle) imaginary axis is M, and the longitudinal imaginary axis is defined as N. In the example shown in Fig. 4, the direction in which the front rubber bushing 1 is easily deformed (direction of the central axis of the cylindrical rubber bushing) lies within the horizontal plane and tilts inward at the rear, and the direction in which the rear rubber bushing 3 is easily deformed is within the horizontal plane. The tire is tilted inward at the front. Lateral force S acts on the tire's ground point G from outside to the inside, brake force B acts on the tire's ground point G from the front to the rear, and engine braking force E acts on the wheel center W from the front to the rear, and the driving force K acts on the wheel center W from the back to the front.When the lateral force S acts on the grounding point G from the outside to the inside, the ball joint 4 is in the first quadrant, so a rotational moment in the toe-in direction is generated around the L axis,
The tire is displaced toe-in. At this time, if the hardness of the front rubber bushing 1 is made smaller than the hardness of the rear rubber bushing 3, the toe-in effect can be obtained more easily. Furthermore, brake force B, engine brake E,
The toe-in effect on the driving force K will be explained. When the braking force B acts on the ground contact point G from front to back, the tire tries to toe in around the L axis due to the offset (-) at the ground contact point G, but at the same time, the tire tries to toe in around the M axis in a counterclockwise direction (in the drawing). (as seen from the left). This counterclockwise rotation is guided by the inclination direction of the two rubber bushes 1 and 3 so that the front side is displaced inwardly and the rear side is displaced outwardly, resulting in a toe-in displacement of the tire. This effect is greater as the offset (G-) at the grounding point G is larger and as the hardness of the rubber bushes 1, 3 is smaller. When the engine braking force E acts on the wheel center W from front to back, the tire tends to displace counterclockwise around the M axis. The counterclockwise displacement around the M axis causes toe-in displacement depending on the orientation of the rubber bushes 1 and 3, as in the case of the brake force B, so that the tire is effectively directed in the toe-in direction. When the driving force K acts on the wheel center W from rear to front, this is a force in the opposite direction to the engine braking force E, so the tire tends to toe-in around the L axis, rotate around the M axis, and rotate the rubber bushes 1 and 3. As a result of the overall effect of the tendency to toe out due to the inclination, it tends to toe out. Therefore, if a stopper (indicated by 13b' in Fig. 5A) is provided in front of either one of the rubber bushes 1 and 3, the offset (W+) at the wheel center W will cause the rubber bush on which the stopper is provided to be connected to the ball joint. A moment that rotates the tire in the toe-in direction acts around the line connecting 4, and the tire is oriented in the toe-in direction. The above explanation is for the case where the offset is W+G-, but the same effect can be obtained with W+G+ or W-G-. Next, the case of W+G+ offset will be explained in detail with reference to FIG. In this case, the orientation of the rubber bushes 1 and 3 may be the same as in the case of FIG. When the lateral force S acts on the grounding point G from the outside to the inside, the tire rotates around the L axis in the toe-in direction because the ball joint 4 is located in the first quadrant. Note that this lateral force S also tries to displace the tire around the N-axis, but to counter this, the toe-in effect can be further improved by making the hardness of the front rubber bushing 1 smaller than the hardness of the rear rubber bushing 3. It can be made larger. For brake B, a toe-out force is also generated due to the offset of W+G+, but if the magnitude of this offset is small, this effect is small, and the rotation around the M axis is guided in the toe-in direction by the inclination of the rubber bushes 1 and 3. By this,
As a result, it becomes possible to cause toe-in displacement. Similarly, with respect to the engine braking force E, the tire can be toe-in by guiding the rotation around the M axis by the rubber bushes 1 and 3. As for the driving force K, as in the case of Fig. 7, this is an external force that is exactly opposite to the engine braking force E, so by providing a stopper in front of either one of the rubber bushes 1 and 3, the stopper can be suppressed. Rubber bush and ball joint 4 provided
The tire is rotated in the toe-in direction around the line connecting the lines, and a toe-in effect can be obtained. In this way, even if the offset is W+G+, the tire will basically absorb the lateral force S due to the action of the ball joint 4 located in the first quadrant and the rubber bushes 1 and 3 located in the second and fourth quadrants. Initially, it is always displaced in the toe-in direction in response to the above four types of external forces. Next, the case where the offset becomes W-G- will be explained with reference to FIG. In this case, the rubber bushes 1 and 3 are tilted in the opposite direction to those shown in FIGS. 7 and 8 in order to cause toe-in displacement even in response to external forces other than the lateral force S. That is, the central axis of the front bushing 1 extends from the front or top toward the inside, and the central axis of the rear bushing 3 extends from the front outside to the rear inside. In the embodiment shown in FIG. 9, the lateral force S rotates the wheel hub in the toe-in direction around the L axis as in the above two embodiments, and the brake force B and the engine brake force E are adjusted to L by the offset WG-. Rotate around the axis in the toe-in direction. However, in the case of these braking forces B and E, rubber bushes 1,
If a stopper is not provided after either one of 3,
Due to the guidance by the orientation of the rubber bushes 1 and 3, the rubber bushes are displaced in the toe-out direction. With respect to the driving force K, the rotation around the M axis is guided in the toe-in direction by the orientation of the two rubber bushes 1 and 3, and a toe-in displacement can occur. The orientation of these rubber bushes 1 and 3 is offset W-G.
This is to cause a displacement toward toe-in even with respect to the driving force K that acts only in the toe-out direction with respect to -. In this way, even if the offset is W-G-, it is possible to provide a toe-in effect with respect to all of the above four types of external forces. The anti-toe-in effects of the four types of external forces in the various embodiments described above can be summarized as shown in the table below. The symbols in the table mean those in the above explanation.

[Table] In the table, the axis represents the related rotation axis, and the stopper represents the required position of the stopper. As is clear from the above embodiments, when using offset, rotation around the L axis is involved.
When using the inclination of the rubber bushing, the rotation of the plane around the M axis (the plane formed by the ball joint and the two rubber bushes) is involved. The magnitude of the displacement caused by displacing and guiding these rotations or rotations can be adjusted by selecting the offset size, the inclination of the rubber bushing, or the hardness of the rubber bushing so that the tire is displaced in the toe-in direction as a result. Thus, the desired toe-in effect can be obtained. According to the present invention, as is clear from the above explanation, one ball joint placed in the first quadrant, one rubber bush (elastic body bush) placed in the fourth quadrant, and one rubber bush (elastic body bush) placed in the second quadrant. Another rubber bush located in the front provides a rear suspension that constantly toes the tires in response to four types of external forces: lateral force, braking force, engine braking force, and driving force, so during driving such as cornering. This makes it possible to realize a car that is more stable and has improved handling without compromising ride comfort. Further, this toe-in effect is advantageous in realizing a sports car with excellent straight-line performance at high speed, so the rear suspension according to the present invention has extremely high practical value.

[Brief explanation of the drawing]

Figures 1 to 6 show an embodiment in which the present invention is applied to a semi-trailing type rear suspension. Figure 1 is a plan view of the right rear wheel, and Figure 2 is a view from the right side of the vehicle body. Figure 3 is an elevational view of the rear view, with the tire section cut out or omitted so that the suspension section can be clearly seen, and Figure 4A is the same as A-A in Figure 2. 4B is a sectional view taken along line A'-A' of FIG. 4A, FIG. 5A is a sectional view taken along line B-B of FIG.
The figure is a sectional view taken along the line B'-B' in FIG. 5A, FIG. 6 is a sectional view taken along the line C-C in FIG. 2, and FIG.
An example of G- is shown in FIG. 8, where the offset is W+
FIG. 9 is a principle diagram showing an example of the present invention in which the offset is W-G-. 1, 3...Rubber bush, 4...Ball joint, G...Grounding point, W...Wheel center,
S...Lateral force, B...Brake force, E...Engine brake force, K...Driving force, L...Vertical axis passing through the ball joint, M...Horizontal axis passing through the ball joint (parallel to the axle) N...Anteroposterior axis passing through the ball joint,...First quadrant,...Second axis
Quadrant,...3rd quadrant,...4th quadrant.

Claims (1)

[Claims] 1. A vehicle body side support member that is partially connected to the vehicle body, a wheel hub that rotatably supports the rear wheel,
1 between this wheel hub and the vehicle body side support member.
The wheel hub is composed of a ball joint that is swingably connected around a point, and two elastic bushings that elastically connect the wheel hub and the vehicle body side support member, and the ball joint is viewed from the left side of the vehicle body. The rear suspension is located in the first quadrant of the horizontal-vertical coordinates based on the wheel center, one of the two elastic bushings is located in the fourth quadrant, and the other is located in the second quadrant.