JP2009126201A - Rear suspension device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provides a rear suspension device capable of decreasing moment about a virtual king pin shaft against tire lateral force. <P>SOLUTION: In vehicle side surface view, the virtual king pin shaft K is tilted forward, and a grounding point K1 of the virtual king pin shaft K is set to position within a distribution range in which a tire 1a can ground. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rear suspension device for suspending a rear wheel of a vehicle.

As a conventional rear suspension device, for example, there is a rear suspension device described in Patent Document 1.
That is, a wheel side end portion of a radius rod extending obliquely in a substantially longitudinal direction of the vehicle is swingably connected to a lower portion of an axle housing that rotatably supports the vehicle. Further, the wheel side end portions of two lower links (lateral links) extending substantially in the vehicle width direction are connected to the lower portion of the axle housing so as to be swingable. Furthermore, the wheel side end portion of the upper arm extending substantially in the vehicle width direction is connected to the upper portion of the axle housing in a swingable manner. Further, the vehicle body side end portions of the radius rod, the two lower links, and the upper arm are slidably connected to a vehicle body frame or a suspension member.

The virtual kingpin axis is defined by the upper rotation center point determined by the wheel side attachment point of the upper arm and the lower virtual rotation center point determined by the link axis line of the two lower links.
Japanese Utility Model Publication 8-1-1923

In the rear suspension apparatus as described above, the virtual kingpin shaft is tilted rearward so that the upper side is the rearward direction of the vehicle in the vehicle side view, and the grounding point of the virtual kingpin shaft is in contact with the tire. It is ahead of the vehicle front-rear direction from the point (on the vertical line of the wheel center). For this reason, the moment about the virtual kingpin axis with respect to the tire lateral force is increased, and the input to the link for controlling the toe angle is increased. Further, when the rear wheel steering device is attached, there is a problem that the required output of the rear wheel steering device is increased by the increase in the moment.
The present invention has been made paying attention to the above points, and an object of the present invention is to provide a rear suspension device capable of reducing a moment around a virtual kingpin axis with respect to a tire lateral force.

  In order to solve the above-described problems, the rear suspension apparatus of the present invention sets the grounding point of the virtual kingpin shaft defined by the suspension arm so as to be within a distribution range in which the tire can ground when viewed from the side of the vehicle.

  According to the present invention, the moment about the virtual kingpin axis with respect to the tire lateral force can be set small.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a rear suspension apparatus according to the present embodiment. FIG. 2 is a vehicle side view showing the rear suspension device. FIG. 3 is a top view showing the rear suspension device. FIG. 4 is a front view of the vehicle showing the rear suspension device.
(Constitution)
In the rear suspension device of this embodiment, as shown in FIGS. 1 to 4, a lower portion of an axle housing 2 that rotatably supports a wheel 1 and a suspension member 3 are connected by two lower links 4 and 5. . Further, the upper part of the axle housing 2 and the suspension member 3 are connected by the upper arm 6. Further, the axle housing 2 and the suspension member 3 are connected by a toe control link 7.

  The two lower links 4 and 5 are spaced apart from each other in the vehicle front-rear direction and extend substantially in the vehicle width direction. Of the two lower links 4, 5, the vehicle body side end of the front lower link 4 (hereinafter also referred to as the front lower link 4) on the front side in the vehicle longitudinal direction is connected to the bracket 10 attached to the lower part of the suspension member 3. It is connected through a bush so that it can swing. Further, the wheel side end portion 4a of the front lower link 4 is connected to the lower portion of the axle housing 2 through a bush so as to be swingable.

Here, the center position of the bush is the attachment point to the axle housing 2 and the suspension member 3 in the front lower link 4. A line passing through the attachment point is a link axis L1 of the front lower link 4. The same applies to the rear lower link 5 and the like.
As shown in FIG. 3, the link axis L1 of the front lower link 4 is inclined with respect to the vehicle width direction so as to go rearward in the vehicle front-rear direction as it goes from the inner side to the outer side in the vehicle width direction. .

  Further, the vehicle body side end portion of the rear lower link 5 on the rear side in the vehicle longitudinal direction (hereinafter also referred to as the rear lower link 5) can swing with respect to the bracket 11 attached to the lower portion of the suspension member 3 via a bush. It is linked to. Further, the wheel side end portion 5a of the rear lower link 5 is connected to the lower portion of the axle housing 2 through a bush so as to be swingable. As shown in FIG. 3, the link axis L <b> 2 of the rear side lower link 5 is inclined with respect to the vehicle width direction so as to go to the front side in the vehicle front-rear direction as it goes from the inner side to the outer side in the vehicle width direction. .

  In this way, the two lower links 4 and 5 are arranged in a square shape in which the distance on the wheel side is narrower when viewed from above. Then, in a top view, the wheel side end portions 4a and 5a of the two lower links 4 and 5 are arranged as shown in FIG. 2 with a vertical line S passing through the wheel center W / C interposed therebetween. However, in the present embodiment, the wheel side end 4 a of the front lower link 4 is disposed relatively below the wheel side end 5 a of the rear lower link 5.

Further, as shown in FIG. 3, the inclination of the link axis lines L <b> 1 and L <b> 2 of the two lower links 4 and 5 with respect to the vehicle width direction is greater than that of the rear lower link 5 with respect to the front lower link 4. Is set larger.
The intersection of the link axes L1 and L2 of the two lower links 4 and 5 in the top view is, as shown in FIG. 2, on the vertical line S passing through the wheel center W / C or slightly in the vehicle side view. Located behind the vehicle in the longitudinal direction. The intersection of the link axes L1 and L2 of the two lower links 4 and 5 is referred to as a lower virtual rotation center point LP.

On the other hand, the wheel side end of the upper arm 6 is connected to the upper portion of the axle housing 2 by a ball joint 13. The upper arm 6 is composed of an A arm, and the two end portions on the vehicle body side are fixed to the suspension member 3 via bushes and connected to the brackets 14 and 15, respectively.
The center position of the ball joint 13 that connects the wheel side end of the upper arm 6 to the axle housing 2 is referred to as an upper rotation center point UP. The upper rotation center point UP is located on the front side in the vehicle front-rear direction with respect to the wheel center W / C position, that is, on the front side in the vehicle front-rear direction with respect to the lower virtual rotation center point LP. Further, the upper rotation center point UP is located on the inner side in the vehicle width direction with respect to the lower virtual rotation center point LP.

  Thereby, the virtual kingpin axis K passing through the upper rotation center point UP and the lower virtual rotation center point LP is rearward in the vehicle front-rear direction as it goes from the upper side to the lower side with respect to the vertical line S in the vehicle side view. It is inclined to head. Further, the virtual kingpin axis K is inclined with respect to the vertical line S so as to go outward in the vehicle width direction from the upper side to the lower side in the vehicle front view. In the top view, the ground contact point K1 of the virtual kingpin axis K is located outward in the vehicle width direction from the center position in the width direction of the tire 1a.

Furthermore, the ground contact point K1 of the virtual kingpin axis K is adjusted so as to be located within a distribution range in which the tire 1a can be grounded. The distribution range in which the tire 1a can be grounded is determined in advance depending on the rigidity of the target tire 1a, the performance of the vehicle, and the like. In addition, the distribution range in which the tire 1a can be grounded is the same as the distribution range of the pneumatic trail.
In the present embodiment, the grounding point K1 of the virtual kingpin axis K is located at the grounding point position within the distribution range in which the tire 1a can be grounded and the maximum probability density of the distribution of the pneumatic trail in the vehicle side view. Is set to be located. That is, the grounding point K1 of the virtual kingpin axis K in the vehicle side view is located at or near the grounding point position that provides the maximum probability density of the distribution of the pneumatic trail. The distribution of the pneumatic trail is, for example, as shown in FIG. 5, and the position of the maximum probability density N is located slightly behind the tire 1a ground contact point in the vehicle front-rear direction. In the example of FIG. 5, it is located about 20 mm behind the tire ground contact point (vertical line S position).

In addition, the rear portion of the axle housing 2 in the longitudinal direction of the vehicle and the suspension member 3 are connected to each other by a toe control link 7 extending in the vehicle width direction. The link axis of the toe control link 7 is set to have a smaller inclination with respect to the vehicle width direction than the link axes L1 and L2 of the two lower links 4 and 5.
Here, the suspension geometry is set so that the input sharing relationship of the front lower link 4, the rear lower link 5, and the toe control link 7 with respect to the lateral force input to the tire 1a is as follows. is doing.
Rear lower link 5> Front lower link 4> Toe control link 7

As shown in FIG. 1, the suspension member 3 includes a left and right side member 16 extending substantially in the vehicle front-rear direction, and two cross members 17 and 18 that connect the side members 16 in a top view. It is configured in a shape. In FIG. 1, only one side member 16 is shown, but the rear suspension device of the wheel on the opposite side in the vehicle width direction is connected to a side member (not shown). The suspension member 3 is elastically supported on the vehicle body frame via an insulator 19 provided on the side member 16.
In the present embodiment, the vehicle body side end portion of the rear lower link 5 and the vehicle body side end portion of the toe control link 7 are both connected to the rear cross member 18 via a bracket.
Here, the axle housing 2 constitutes a wheel support member. The suspension member 3 constitutes a vehicle body side member.

(Effect of this embodiment)
(1) The grounding point K1 of the virtual kingpin axis K is positioned within the distribution range where the tire 1a is grounded when viewed from the side of the vehicle. As a result, the moment about the virtual kingpin axis K with respect to the lateral force input to the tire 1a is reduced. This reduces the input to the toe control link 7 and facilitates securing the lateral force compliance steer in the understeer direction. And the stability of the vehicle at the time of turning improves.
Further, when the movable portion of the rear wheel steering device is attached to the axle housing 2 instead of the toe control link 7, the moment around the virtual kingpin axis K is reduced as described above. The required output of the rudder device is reduced. That is, as a result of being able to suppress the driving force of the rear wheel steering device to be small, the rear wheel steering performance is improved. Further, the rear wheel steering device can be reduced in weight.
The straight running performance of the vehicle can be ensured by the front suspension device.

(2) In particular, in the vehicle side view, the ground contact point K1 of the virtual kingpin axis K is set at the ground contact point position having the maximum probability density in the probability density of the distribution of the pneumatic trail. As a result, the moment around the virtual kingpin axis K can be further reduced.
The moment about the virtual kingpin axis K is proportional to the distance between the grounding point K1 of the virtual kingpin axis K and the pneumatic trail. Then, by setting the contact point K1 of the virtual kingpin axis K at the contact point position that is the maximum probability density in the probability density of the distribution of the pneumatic trail that is most likely to become a pneumatic trail, the probability of reducing the distance is increased. I can do it.

(3) Further, by tilting the virtual kingpin axis K so that the upper side is the front side in the vehicle front-rear direction, the grounding point K1 of the virtual kingpin axis K is perpendicular to the wheel line W / C. This makes it easier to set the vehicle rearward in the longitudinal direction. In other words, it is easy to locate the tire 1a within the distribution range where the tire 1a comes into contact with the side view of the vehicle.
(4) Further, in the top view, the inclination of the front lower link 4 is made larger than the rear lower link 5 in the vehicle width direction. Accordingly, the lower virtual rotation center point LP can be easily arranged in the vehicle front-rear direction, and the ground contact point K1 of the virtual kingpin axis K can be easily located in the distribution range where the tire 1a comes into contact with the vehicle side view. It becomes.

(5) The relationship of the input sharing of the front lower link 4, the rear lower link 5, and the toe control link 7 with respect to the lateral force input is as follows: the rear lower link 5> the front lower link 4> the toe control link 7. It is set to be.
By adjusting the mounting position so that it is shared in this way, it is possible to suppress the reduction in camber rigidity by making the lateral force compliance understeer. That is, the input to the toe control link 7 is reduced while ensuring the camber rigidity, and it becomes easy to ensure the lateral force compliance steer in the understeer direction.

At this time, the rear lower link 5 and the toe control link 7 are arranged behind the wheel center W / C in the longitudinal direction of the vehicle. Furthermore, the vehicle body side end portions of the rear lower link 5 and the toe control link 7 are preferably connected to a cross member 18 that extends in the vehicle width direction of the suspension member 3.
With this setting, the way of receiving the force is set so that the rear lower link 5> the front lower link 4> the toe control link 7, so when the suspension undergoes toe deformation, the input at that time is Mainly received by the side lower link 5 and the toe control link 7. As a result, the elastic deformation of the cross member 18 of the suspension member 3 is mainly performed, and the vibration transmission rate of the suspension member 3 to the vehicle body is reduced.

(6) The grounding point K1 of the virtual kingpin axis K is located on the vehicle outer side from the grounding point of the tire 1a in the vehicle plan view. As a result, when a braking force is applied to the tire 1a, a moment around the virtual kingpin axis K acts to deform the tire 1a in the toe-in direction. That is, it becomes easy to make the longitudinal force compliance steer S understeer.
(7) The upper rotation center point UP, which is the attachment point of the upper arm 6 on the vehicle body side, is arranged on the inner side in the vehicle width direction than the lower virtual rotation center point LP. This makes it easier for the grounding point K1 of the virtual kingpin axis K to be positioned on the vehicle outer side than the grounding point of the tire 1a in plan view of the vehicle.

(Modification)
(1) In the above embodiment, the grounding point K1 of the virtual kingpin axis K is set at or near the grounding point position where the maximum probability density of the distribution of the pneumatic trail is within the distribution range where the tire 1a can ground. Yes.
Instead, the ground contact point K1 of the virtual kingpin axis K is within the distribution range where the tire 1a can be grounded, the ground contact point position having the maximum probability density of the distribution of the pneumatic trail, and the vehicle longitudinal direction from the ground contact point It may be set backward. As can be seen from FIG. 5, since the area of the distribution after the maximum probability density position is large, it is easy to set the moment about the virtual kingpin axis K smaller than the front side of the position of the maximum probability density.

It is a perspective view which shows the rear suspension apparatus which concerns on embodiment based on this invention. It is a vehicle side view which shows the rear suspension apparatus which concerns on embodiment based on this invention. It is a top view which shows the rear suspension apparatus which concerns on embodiment based on this invention. It is a vehicle front view which shows the rear suspension apparatus which concerns on embodiment based on this invention. It is a figure which shows the example of probability density distribution of a pneumatic trail.

Explanation of symbols

1 Wheel 1a Tire 2 Axle housing (wheel support member)
3 Suspension member (vehicle body side member)
4 Front-side lower link 4a Wheel-side end 5 Rear-side lower link 5a Wheel-side end 6 Upper arm 7 Toe control link K Virtual kingpin axis K1 Virtual kingpin axis grounding point UP Upper rotation center point LP Lower virtual rotation center point L1 Link axis L2 of the front lower link Link axis W / C wheel center of the rear lower link

Claims (7)

In a rear suspension device in which a wheel support member for supporting a wheel and a vehicle body side member are connected by a suspension arm,
A rear suspension apparatus, wherein the suspension arm is set so that a grounding point of a virtual kingpin shaft is located within a distribution range in which a target tire can be grounded in a side view of the vehicle.   2. The rear suspension according to claim 1, wherein a grounding point of a virtual kingpin shaft in a side view of the vehicle is set at or near a grounding point position that provides a maximum probability density of a pneumatic trail distribution in a target tire. apparatus.   In the target tire, the grounding point position that is the maximum probability density of the distribution of the pneumatic trail, and the grounding point of the virtual kingpin shaft in the vehicle front-rear direction from the grounding point that is the maximum probability density in the vehicle front-rear direction The rear suspension device according to claim 1, wherein the rear suspension device is set. The suspension arm includes two lower links and an upper arm,
By adjusting the setting of the two lower links, the grounding point of the virtual kingpin shaft in the vehicle side view is positioned within a distribution range where the tire can ground. Item 4. The rear suspension device according to any one of items 3 to 3.   For each link axis passing through the attachment point to the wheel support member and the attachment point to the vehicle body side member in the two lower links, the link axis of the lower link on the front side in the vehicle front-rear direction in the vehicle top view is: The vehicle is inclined to the rear in the vehicle longitudinal direction as it goes from the inner side to the outer side in the vehicle width direction. The link axis of the lower link on the front side in the vehicle front-rear direction is larger than the link axis of the lower link on the rear side in the vehicle front-rear direction with respect to the vehicle width direction. The rear suspension apparatus according to claim 4, wherein   The ground contact point of the virtual kingpin shaft is set on the vehicle width direction outer side than the ground contact point in the vehicle width direction center of the tire when viewed from the top of the vehicle. Rear suspension device.   The wheel-side attachment point of the upper arm is set inward in the vehicle width direction with respect to the virtual rotation center point below the virtual kingpin shaft determined by two lower links in the vehicle top view. The rear suspension device according to any one of claims 6 to 6.

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