JP3645447B2 - Trailing arm suspension - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a trailing arm type suspension used as a rear suspension of a vehicle such as an automobile.
[0002]
[Prior art]
Conventionally, an example of this type of trailing arm type suspension is disclosed in Japanese Patent Laid-Open No. 10-315730. As shown in FIG. 7 of the present application, the suspension described in this publication has a front end of a trailing arm 92 rotatably connected to a bracket 91 of a frame 90 that constitutes a vehicle body. A bracket 94 fixedly attached to the end portion in the longitudinal direction is connected to the rear portion of the trailing arm 92 via two rubber bushings 95A and 95B. The two rubber bushes 95A and 95B are disposed in front of the vehicle with respect to the center Pa of the axle beam 93. According to such a configuration, the degree of freedom in setting the interval dimension between the two rubber bushes 95A and 95B is increased, and the vehicle can be easily rolled as the interval dimension is reduced, so that the roll rigidity can be easily adjusted. The advantage that it can be made is obtained.
[0003]
[Problems to be solved by the invention]
However, the conventional suspension has the following problems.
[0004]
First, in the conventional suspension, when there is an input to the suspension, the force is always received by the two rubber bushes 95A and 95B, and the rubber is greatly increased in both of these two rubber bushes 95A and 95B. It is intended to mitigate the impact at the time of input by elastically deforming. Therefore, in the past, due to the presence of the two rubber bushes 95A and 95B, the overall compliance of the suspension tends to be excessive, giving the vehicle occupant the impression that the vehicle suspension is unstable. In some cases, the ride comfort of the vehicle deteriorates. The compliance in the specification of the present application corresponds to the reciprocal of “stiffness (magnitude of resistance to external force)”, and is a concept indicating the degree of softness of the mechanism, the constituent members, and the like.
[0005]
Secondly, conventionally, the characteristics of the axle steer when the vehicle turns may not be set to understeer. That is, the phenomenon of axle steer when the vehicle turns is not only that the longitudinal ends of the axle beam 93 are displaced in the longitudinal direction of the vehicle due to the bounding and rebounding of the two left and right trailing arms 92. It is also caused by the deformation of the rubbers of the rubber bushes 95A and 95B. For example, as shown in FIG. 8, when the trailing arm 92 on the outer ring side when the vehicle turns is bounded above the horizontal line H and the trailing arm 92 on the inner ring side rebounds downward, the axle beam 93 Although a torsional force and a bending force are generated, the rigid axle beam 93 itself is not easily deformed, and these forces are borne by the two rubber bushings 95A and 95B. Then, as a result of the rubbers of these rubber bushes 95A and 95B being deformed in the directions of the arrows Na to Nd in the figure, the centers Pa of the both ends of the axle beam 93 are intermediate points Pb between the two rubber bushes 95A and 95B. Is rotated in the directions of arrows Ne and Nf. In the conventional suspension, as a result of such an action, both ends of the axle beam 93 are displaced rearward of the vehicle on both the bound and rebound sides. However, the phenomenon in which the end of the axle beam 93 on the bounce side (outer wheel side) is displaced rearward of the vehicle makes the rear wheel toe out and causes oversteer.
[0006]
The invention of the present application has been conceived under such circumstances, and the compliance of the entire trailing arm type suspension is prevented from becoming excessive so as to improve the riding comfort of the vehicle, and the roll of the vehicle. The problem is to be able to reliably eliminate or alleviate the phenomenon of oversteering at times.
[0007]
DISCLOSURE OF THE INVENTION
In order to solve the above problems, the present invention takes the following technical means.
[0008]
According to the present invention, a trailing arm suspension is provided. This trailing arm type suspension is provided with a pair of trailing arms arranged at intervals in the vehicle width direction and having a front end connected to the vehicle body so as to be swingable in the vehicle height direction, and an axle beam. A pair of brackets fixedly provided at both ends in the longitudinal direction and a first connecting portion arranged so as to overlap each other in the vehicle width direction and connecting each bracket to the rear portion of each trailing arm And a second connecting portion, a trailing arm suspension, wherein the first connecting portion is formed with a rubber bush, and the second connecting portion is above in conjunction with the compliance is smaller than the first connecting portion is disposed above the center of the first connecting section and the axle beam, each tray Nguamu is characterized in that rotation center axis to allow rotating the respective bracket when the rubber bushing is deformed is configured to extend parallel above the axle beam substantially by bounces or rebounds.
[0009]
According to the present invention, the following effects can be obtained.
[0010]
First, the first connecting portion and the second connecting portion that connect the brackets at both ends of the axle beam to the respective trailing arms have different compliances, and the first connecting portion is soft. In contrast, the second connecting portion is hard. For example, the second connecting portion can be configured using a ball joint instead of the rubber bush. Therefore, compared to a conventional suspension that uses two soft rubber bushes and the axle beam bracket is connected to the trailing arm, the overall suspension can be made less compliant and the undercarriage of the vehicle is unstable. Can not be given to the passenger. Of course, when there is an input to the suspension, the impact caused by the force can be appropriately mitigated by deformation of the rubber bushing of the first connecting portion. For this reason, according to this invention, the riding comfort of a vehicle can be made favorable rather than the conventional suspension.
[0011]
Second, when the vehicle is turning, when the outer ring side trailing arm bounces and the inner ring side trailing arm rebounds and a torsional force or bending force acts on the axle beam, Due to the difference in compliance with the second connecting portion, the brackets and the axle beam can be rotated around the second connecting portion on the smaller compliance side. Since the second connecting portion is positioned above the center of the first connecting portion and the axle beam, the rotation center when the brackets and the axle beam rotate is always higher than the center of the axle beam. Will also be above. Then, at the time of turning of the vehicle, it is possible to positively displace one end portion of the axle wheel on the outer ring side that is in the bound state toward the front of the vehicle, and the other end portion of the axle beam on the inner ring side that is in the rebound state. Can be positively displaced rearward of the vehicle. Therefore, it is easier and more reliable to set the axle steer characteristics to understeer or understeer.
[0012]
In a preferred embodiment of the present invention, the first connecting portion is disposed in front of or behind the axle beam, and the second connecting portion is disposed immediately above the axle beam. .
[0013]
According to such a configuration, when there is horizontal input to the axle beam, the force can be efficiently received mainly by the first connecting portion, and the impact caused by the input can be reduced. it can. On the other hand, when there is an input in the vehicle height direction to the axle beam, the force is mainly received by the second connecting portion, but this second connecting portion is so-called hard. The second connecting part itself does not exhibit a sufficient buffer function. Therefore, input in the vehicle height direction can be appropriately dealt with by the combined action of the suspension spring and shock absorber functions provided in the suspension and the swinging motion of the trailing arm. It is possible to make the ride comfort of the vehicle better by fully exhibiting the function.
[0014]
In another preferred embodiment of the present invention, a shock absorber is attached to each trailing arm, and the rubber of the rubber bush of the first connecting portion is larger than the spring constant in the vehicle longitudinal direction. The spring constant in the vehicle height direction is increased.
[0015]
According to such a configuration, the first connecting portion exhibits a good buffer function for the force in the vehicle longitudinal direction of the suspension, but has a good buffer function for the force in the vehicle height direction. It can be a non-exhibiting one. Therefore, the effect of the shock absorber with respect to the force in the vehicle height direction can be increased, and the riding comfort of the vehicle can be further improved.
[0016]
Other features and advantages of the present invention will become more apparent from the following description of embodiments of the invention.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be specifically described with reference to the drawings.
[0018]
FIG. 1 is a schematic plan view showing an example of a trailing arm suspension according to the present invention. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is an operation explanatory view of the trailing arm type suspension shown in FIGS. 1 and 2. 1 and the subsequent drawings, arrow Fr indicates the front of the vehicle, arrow W indicates the vehicle width direction, and arrow Up indicates the upper side in the vehicle height direction.
[0019]
The trailing arm suspension shown in FIG. 1 is a so-called three-link suspension, and a pair of trailing arms 1, 1 (1A, 11B), an axle beam 2, and both longitudinal ends of the axle beam 2 It comprises a set of brackets 3 and 3 attached to and parts to be described later.
[0020]
The pair of trailing arms 1, 1 are arranged at an appropriate interval in the vehicle width direction and extend in the vehicle front-rear direction. Each of these front portions 10 is rotatably connected to the vehicle body 5 via a shaft 50, and each trailing arm 1 can swing in the vehicle height direction about the shaft 50. The axle beam 2 has a pipe shape in which a rear wheel axle 20 is internally provided, and extends in the vehicle width direction so that both longitudinal ends thereof intersect the trailing arms 1. The axle 20 may be either a drive shaft or a driven shaft. When the axle 20 is a drive shaft, a housing portion 21 is provided at the center in the longitudinal direction of the axle beam 2 to house a final reduction gear. It is done.
[0021]
As shown in FIG. 2, each bracket 3 is made of a metal plate or a sheet metal member having a shape capable of sandwiching rubber bushes 40 and 41, which will be described later, from both ends thereof, and fixed to the outer peripheral surface of the axle beam 2 by welding, for example. It has been. Each bracket 3 is connected to the rear portion of each trailing arm 1 via a first connecting portion 4A and a second connecting portion 4B configured to include rubber bushes 40, 41 having different rubber spring constants. The trailing arm suspension of this embodiment has the greatest feature in the structure of this portion.
[0022]
The rubber bush 40 constituting the first connecting portion 4A has the same configuration as a general rubber bush, and a rubber 40c is interposed between a metal outer cylinder 40a and an inner cylinder 40b. The basic configuration of such a rubber bush is the same for the rubber bush 41 and a rubber bush 42 described later. However, the rubber 40c of the rubber bush 40 is provided with two screw holes 40d positioned at the front and rear of the inner cylinder 40b, and the spring constant of the rubber 40c in the vehicle height direction is greater than the spring constant in the vehicle front-rear direction. Is getting bigger. The rubber bush 40 is disposed in front of the axle beam 2, and the outer cylinder 40 a is welded to the trailing arm 1. The rubber bush 40 and the bracket 3 are connected using a shaft body 43 such as a bolt inserted through the inner cylinder 40b.
[0023]
In the rubber bush 41 constituting the second connecting portion 4B, the spring constant of the rubber 41c is considerably larger than the spring constant of the rubber 40c of the rubber bush 40 (either in the vehicle height direction or the vehicle height direction). It is a value. Thereby, the compliance of the second connecting portion 4B is smaller than that of the first connecting portion 4A. Further, the thickness of the rubber 41c is considerably thinner than that of the rubber 40c, and a rubber bush 41 having a smaller size than the rubber bush 40 is used. If it does in this way, it will become easy to secure the attachment space of rubber bush 41. The rubber bush 41 is disposed immediately above the axle beam 2 so that the center thereof is located above the center P of the axle beam 2, and the outer cylinder is welded to the trailing arm 1. The rubber bush 41 and the bracket 3 are connected by using a shaft body 44 inserted through the inner cylinder of the rubber bush 41.
[0024]
The above-described connection structure between the bracket 3 and the trailing arm 1 is provided in any of the pair of trailing arms 1 and 1. Further, a rear end portion of each trailing arm 1 is provided with a portion that extends rearward of the vehicle and to which a rubber bush 42 is attached. The rubber bush 42 has a shock absorber having an upper end coupled to the vehicle body 5. The lower end of 59 is connected.
[0025]
Next, the operation of the trailing arm suspension having the above-described configuration will be described.
[0026]
First, as shown by the solid line in FIG. 3, when the trailing arm 1 is set in a substantially horizontal posture, when the vehicle turns and rolls, the tray on the outer ring side is shown as indicated by the phantom line in FIG. Ring arm 1 (1B) bounces in the direction of arrow N1. The trailing arm 1 (1A) on the inner ring side rebounds in the direction of the arrow N2. At that time, a torsional force and a bending force are generated in the axle beam 2, and a force in a direction to return each bracket 3 to the original posture is applied to the first connecting portion 4A and the second connecting portion 4B. work. However, since the rubber of the rubber bush 41 of the second connecting portion 4B is hard and difficult to deform, the rubber of the rubber bush 40 of the first connecting portion 4A is deformed prior to the rubber of the rubber bush 41 by the above force. As a result, the bracket 3 rotates around the shaft body 44 of the second connecting portion 4B.
[0027]
More specifically, in the trailing arm 1 (1B) on the bounce side, the shaft body 43 of the first connecting portion 4A is accompanied by deformation of the rubber of the rubber bush 40 and the shaft of the second connecting portion 4B. It rotates in the direction of arrow N3 about the body 44. For this reason, the bracket 3 and one end of the axle beam 2 also rotate in the same direction around the shaft body 44, and the center P ′ of the one end of the axle beam 2 is displaced toward the vehicle front indicated by the arrow N4. In the trailing arm 1 (1A) on the rebound side, the shaft body 43 of the first connecting portion 4A and the bracket 3 are in the direction of arrow N5 with the shaft body 44 of the second connecting portion 4B as the center, based on the same principle as described above. And the center P ″ of the other end of the axle beam 2 is displaced toward the rear of the vehicle indicated by an arrow N6. As a result, as shown in FIGS. 4 (a) and 4 (b), the vehicle 8 is When turning in the direction of the arrow N7, the end 20b on the outer ring side (bound side) of the axle beam 2 can be arranged in front of the end 20a on the inner ring side (rebound side). The wheels Wa and Wb can be toe-in to make understeer, and the stability and maneuverability of the vehicle can be improved.
[0028]
The above-described understeer characteristic is obtained because the shaft body 44 serving as the rotation center of the bracket 3 and the axle beam 2 is always positioned above the axle beam 2 regardless of whether the trailing arm 1 is bound or rebound. Because it does. In the suspension shown in FIG. 8 as the prior art, the position Pb, which is the rotation center of the axle beam when the trailing arm bounces, is located slightly below the center of the axle beam, and the end of the axle beam is an arrow Ne. In the suspension according to the present embodiment, the end of the bounding axle beam can be displaced toward the front side of the vehicle. Therefore, the suspension of the present embodiment can make the axle steer characteristics more reliably understeer than the conventional suspension. The characteristics of the axle steer described above can be obtained not only when each trailing arm 1 is set in a horizontal posture but also when the trailing arm 1 is set in a downward-lowering posture.
[0029]
In addition, the trailing arm suspension also exhibits the effect of improving the riding comfort of the vehicle during normal traveling as described below. That is, in the trailing arm type suspension, the rubber bushing 41 is hard, whereas the rubber bushing 40 is soft. Therefore, most of the horizontal force acting on the axle beam 2 is rubber. It is possible to relieve the impact in the horizontal direction by causing the bush 41 to bear and the deformation action of the rubber. Therefore, unlike the case where the two rubber bushes 40 and 41 are both soft rubber bushes, the compliance of the entire suspension can be prevented from becoming unduly large, and the operability of the vehicle can be improved. .
[0030]
The rubber bush 40 has a small spring constant in the vehicle front-rear direction and exhibits a buffering function with respect to the force in that direction. On the other hand, the spring constant in the vehicle height direction is large. Does not demonstrate the buffer function. Of course, the rubber bush 41 which is harder than the rubber bush 40 does not exhibit a sufficient buffer function against the force in the vehicle height direction. Therefore, when a force in the vehicle height direction acts on the axle beam 2, the force can be input almost directly to the shock absorber 59, and the performance of the shock absorber 59 can be fully exploited. Therefore, the ride quality of the vehicle can be improved even when the vehicle height direction is input. When the wheel gets over the convex part of the road surface, the horizontal force and the vehicle height force are simultaneously input to the wheel and the axle beam 2, but as described above, in the trailing arm type suspension, In addition, since the appropriate cushioning function can be exhibited for both the horizontal force and the vehicle height direction force, the ride comfort of the vehicle can be improved.
[0031]
5 and 6 are explanatory views showing another example of a trailing arm type suspension according to the present invention. In these drawings, the same or similar elements as those of the previous embodiment are denoted by the same reference numerals as those of the previous embodiment.
[0032]
In the configuration shown in FIG. 5, the rear end portion of the trailing arm 1 extends to the rear of the vehicle with respect to the axle beam 2, and the first connecting portion 4 </ b> A is disposed behind the axle beam 2. The second connecting portion 4B is disposed immediately above the axle beam 2. According to such a configuration, although the position of the first connecting portion 4A is different from the suspension of the previous embodiment, a horizontal force can be appropriately applied to the first connecting portion 4A. The same effect as the suspension of the embodiment can be obtained. Further, since an appropriate space can be secured in front of the axle beam 2, it is possible to provide a suspension spring, for example, in this portion. Thus, the first connecting portion 4 </ b> A may be disposed either in front of or behind the axle beam 2.
[0033]
In the configuration shown in FIG. 6, both the first and second connecting portions 4A and 4B are arranged in front of the axle beam 2, and the axle beam 2 is placed between the first and second connecting portions 4A and 4B. The height is set. Even in such a configuration, the object of the present invention can be achieved as long as the second connecting portion 4B positioned above the center of the axle beam 2 has a smaller compliance than the first connecting portion 4A. An effect is obtained. Thus, in the present invention, in short, the axle beam bracket is connected to the rear portion of the trailing arm via the two connecting portions having different compliances, and one of the connecting portions on the side where the compliance is small (hard). However, it is only necessary to be positioned above the center of the axle beam and the other connecting portion on the side where the compliance is large (soft). Therefore, as already described, a ball joint can be used instead of the rubber bush as the second connecting portion in the present invention.
[0034]
The present invention is not limited to the above-described embodiment, and the specific configuration of each part can be varied in design in various ways.
[Brief description of the drawings]
FIG. 1 is a schematic plan view showing an example of a trailing arm suspension according to the present invention.
FIG. 2 is a cross-sectional view taken along the line II-II in FIG.
3 is an operation explanatory view of the trailing arm type suspension shown in FIGS. 1 and 2. FIG.
4A is a schematic side view showing a rolled state of a vehicle equipped with a trailing arm suspension according to the present invention, and FIG. 4B is a schematic plan view thereof.
FIG. 5 is an explanatory view showing another example of a trailing arm type suspension according to the present invention.
FIG. 6 is an explanatory view showing another example of a trailing arm type suspension according to the present invention.
FIG. 7 is an explanatory diagram showing a conventional example.
FIG. 8 is an operation explanatory diagram of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Trailing arm 2 Axle beam 3 Bracket 4A 1st connection part 4B 2nd connection part 5 Car body 10 Front part (of a trailing arm)
40 Rubber bush 41 Rubber bush 59 Shock absorber

Claims (3)

A pair of trailing arms arranged at intervals in the vehicle width direction and having a front end connected to the vehicle body so as to be swingable in the vehicle height direction;
A set of brackets fixedly provided at both longitudinal ends of the axle beam;
A first connecting portion and a second connecting portion that are arranged to overlap each other in the vehicle width direction and connect the brackets to the rear portions of the trailing arms;
A trailing arm suspension,
The first connecting portion is formed with a rubber bush, and
The second connecting portion has a smaller compliance than the first connecting portion, is disposed above the center of the first connecting portion and the axle beam, and each trailing arm is bounded. Alternatively , a trailing arm suspension characterized in that a rotation center shaft capable of rotating each bracket when the rubber bush is deformed by rebounding extends substantially in parallel with the axle beam. . 2. The trailing arm according to claim 1, wherein the first connecting portion is disposed in front of or behind the axle beam, and the second connecting portion is disposed immediately above the axle beam. Suspension. A shock absorber is attached to each trailing arm, and the rubber constant of the rubber bush of the first connecting portion is greater in the spring constant in the vehicle height direction than in the vehicle longitudinal direction. The trailing arm type suspension according to claim 1 or 2.

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