JP4647279B2 - Rear suspension - Google Patents

Description

  The present invention relates to a rear suspension, and more particularly to a technique for improving riding comfort.

  An example of this type of rear suspension is shown in FIG. 5 (see Patent Document 1). In the accompanying drawings, the direction Fr indicates the front of the vehicle, the direction Up indicates the upper side in the vehicle height direction, and the direction Fr indicates the front of the vehicle.

  The illustrated rear suspension is referred to as a three-link suspension, and has a structure in which both ends of an axle beam (axle housing) 91 are connected to the rear part of a pair of suspension arms 90. Each suspension arm 90 is swingable in the vehicle height direction around this connection location by connecting a rubber bush (not shown) provided at the front thereof to a vehicle body (not shown). . A bracket 93 is attached to each of both ends of the axle beam 91, and the bracket 93 is supported by two rubber bushes 94 and 95 attached to the rear part of each suspension arm 90. The rubber of the rubber bush 94 has a larger spring constant than the rubber of the rubber bush 95. Further, the rubber bush 94 is arranged at a position higher than the rubber bush 95. With such a configuration, it is possible to make the axle steer characteristic look understeer, and the steering stability is improved.

  Further, when the vehicle travels over a small protrusion on the road, the vehicle wheel is allowed to pass through a longer route than when passing through the flat portion. In order to smoothly pass through such a long route, it is necessary to rotate the wheels more than in the case of passing through the flat portion. In the illustrated rear suspension, the rubber bush 95 having a small spring constant has a larger deformation amount than the rubber bush 94 having a large spring constant. For this reason, the bracket 93 is easy to rotate around the axis of the rubber bush 94. Such rotation promotes rotation of the wheels in the traveling direction. Therefore, according to such a structure, the effect which makes it easy to get over the said small protrusion is acquired.

  However, when the speed of the vehicle is relatively high or the protrusion is relatively large, the deformation of the rubber bush 94 may be large, or the rubber bush 95 may be deformed in an unexpected direction, and the bracket 93 is smooth. May not be rotated. In such a case, when overcoming the small protrusion, the rotation of the wheel is insufficient and a drag force to the rear of the vehicle acts, which causes an uncomfortable feeling to the passenger and deteriorates the riding comfort. It was.

Japanese Patent Laying-Open No. 2002-19437 (FIG. 4)

  The present invention has been conceived under the circumstances described above, and it is possible to realize a good ride comfort when the axle steer characteristic is understeered and the small protrusion is overcome. The object is to provide a rear suspension.

  In order to solve the above problems, the present invention takes the following technical means.

  The rear suspension provided by the present invention is separated from each other in the vehicle width direction and extends in the vehicle front-rear direction, and each front part is connected to the vehicle body, so that these front parts are centered. A pair of suspension arms supported so as to be swingable in a vehicle height direction, an axle beam extending in a vehicle width direction, and a first and a rear portion connecting each suspension arm to each end of the axle beam; A rubber constant of the first rubber bush is larger than that of the second rubber bush, and the first rubber bush has the second rubber bush. A rear suspension that is disposed in front of the vehicle with respect to the rubber bush and the axle beam and that is disposed at a position higher than that of the second rubber bush. The second rubber bush includes a shaft center of the first rubber bush arranged on the same side in the vehicle width direction out of the rigidity in a direction orthogonal to the vehicle width direction, and the second rubber bush. It is characterized by the lowest rigidity in the direction orthogonal to the straight line connecting the shaft centers.

  According to such a configuration, the first rubber bush is hardly deformed, and the second rubber bush can be positively deformed in the orthogonal direction. As a result, when the vehicle gets over a small protrusion on the road, the axle beam can be smoothly rotated around the first rubber bush. Since the direction of this rotation is the vehicle traveling direction, it is possible to suppress the vehicle from being dragged backward by the small protrusions. Therefore, it is possible to avoid a steep acceleration in the rear of the vehicle from occurring in the entire vehicle and to further improve the riding comfort.

  In a preferred embodiment of the present invention, the vehicle further includes a third rubber bush that connects the front portion of each suspension arm to the vehicle body, and the first rubber bush includes an axial center and the axle. An arrangement in which a straight line connecting the axis of the beam forms an angle of 0 ° to 20 ° obliquely upward and forward of the vehicle with respect to a line connecting the axis of the third rubber bush and the axis of the axle beam; Has been. According to such a configuration, it is suitable for improving the riding comfort when riding on the small protrusion and for making the axle steer characteristic feel understeer.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

  FIG. 1 shows an example of a rear suspension according to the present invention. The rear suspension A includes an axle beam 1, a pair of suspension arms 2, and a pair of first, second, and third rubber bushes 3A, 3B, 3C.

  The axle beam 1 is a highly rigid tubular member with a built-in axle for transmitting rotational force to the two wheels W. The axle beam 1 extends in the vehicle width direction, and a housing 12 that houses a final reduction gear (not shown) is provided at the center in the longitudinal direction. A pair of brackets 11 is provided at each of the longitudinal ends of the axle beam 1. The bracket 11 is attached with a pair of first and second rubber bushes 3A, 3B.

  As shown in FIG. 2, the first and second rubber bushes 3A, 3B include metal inner cylinders 30A, 30B, outer cylinders 31A, 31B, and rubbers 32A, 32B interposed therebetween. The center axis is oriented in the vehicle width direction. The rubber 32A has a spring constant about six times larger than that of the rubber 32B. The outer cylinders 31A and 31B are welded to the rear part of the suspension arm 2. The bolts 51 and 52 are supported by the bracket 11 and are inserted through the inner cylinders 30A and 30B. With such a structure, the axle beam 1 and the rear part of each suspension arm 2 are connected to each other via the first and second rubber bushes 3A, 3B and the bracket 11.

  The first rubber bush 3A is disposed in front of and above the axle beam 1 and the second rubber bush 3B. A straight line connecting the axis OA of the first rubber bush 3A and the axis P of the axle beam 1 and a straight line connecting the axis P of the third rubber bush 3C and the axle beam 1 form an angle α. In the present embodiment, the angle α is about 11 °. In order to achieve the effect intended by the present invention described later, the angle α is preferably 0 to 20 °. The second rubber bush 3 </ b> B is disposed behind the vehicle with respect to the first rubber bush 3 </ b> A and is located below the axle beam 1. The positional relationship between the shaft centers OA, OB, and P is that in a normal state where the suspension arms 2 are not bound and rebound.

  Each second rubber bush 3B is formed with a pair of substantially arc-shaped cavities 33B. The pair of cavities 33B are separated from each other across the axis OB of the second rubber bush 3B in a direction N2 perpendicular to a straight line connecting the axes OA, OB of the first and second rubber bushes 3A, 3B. is doing. Accordingly, the second rubber bush 3B has the lowest rigidity in the direction N2 among the rigidity in the direction orthogonal to the vehicle width direction. When an external force is applied to the first and second rubber bushes 3A and 3B, the first rubber bush is hardly deformed, and the second rubber bush is likely to be deformed in the direction N2. That is, the bracket 11 is easy to swing around the axis OA of the first rubber bush 3A.

  As shown in FIG. 1, the pair of suspension arms 2 are spaced apart from each other in the vehicle width direction and extend in the vehicle front-rear direction. A third rubber bush 3 </ b> C is attached to the front end portion of each suspension arm 2. The third rubber bush 3 </ b> C is for connecting the suspension arm 2 to the side member 6. The side member 6 is a strength member of the vehicle body.

  As shown in FIG. 2, the third rubber bush 3 </ b> C includes a metal inner cylinder 30 </ b> C and an outer cylinder 31 </ b> C, and a rubber 32 </ b> C interposed between them. The shaft is oriented in the vehicle width direction. A bolt 53 supported by the bracket 61 is inserted through the inner cylinder 30C. With such a structure, each suspension arm 2 is connected to the side member 6 via the bracket 61 and can swing in the vertical direction in the figure around the axis OC while being elastically deformed by the rubber 30C. It has become.

  A pair of substantially arc-shaped cavities 33C is formed in the third rubber bush 3C. The pair of cavities 33C are separated from each other across the axis OC in a direction N3 that forms an angle β obliquely upward and forward of the vehicle with respect to the vehicle longitudinal direction. Accordingly, the third rubber bush 3C has the lowest rigidity in the direction N3 among the rigidity in the direction orthogonal to the vehicle width direction. In the present embodiment, the angle β is about 40 °.

  As shown in FIG. 1, the rear suspension A is provided with a pair of springs 41 and a pair of shock absorbers 42. Each spring 41 is mounted between a pair of spring receiving members 13 a and 13 b attached to each suspension arm 2 and the side member 6. Each shock absorber 42 has a lower end attached to the rear end of each suspension arm 2 and an upper end attached to the side member 6.

  The operation of the rear suspension A will be described below.

  First, a case where a vehicle using the rear suspension A travels over a small protrusion on the road will be described. FIG. 3 is a schematic diagram showing the operation at that time. As shown in the figure, a steep lifting force Fu acts on the wheel. The lifting force Fu acts on the first and second rubber bushes 3A and 3B via the axle beam 1 and the bracket 11. As described above, the first rubber bush 3A hardly deforms, and the second rubber bush 3B tends to deform along the direction N2. Therefore, when the lifting force Fu is applied, the second rubber bush 3B is deformed so that the axis OA moves obliquely upward in the rearward direction of the vehicle along the direction N2. Therefore, the bracket 11 is swung upward by an angle θ about the axis OA. As a result, the wheel is rotated by an angle θ. The direction of this rotation coincides with the direction in which the vehicle travels.

  When getting over the small protrusion, the wheel needs to rotate more by that amount because the wheel is allowed to pass through a longer route than when passing through the flat portion. When the amount of rotation of the wheel is insufficient, the wheel is dragged rearward of the vehicle. However, in the present embodiment, the wheel can be prevented from being dragged by being further rotated by an angle θ in the traveling direction. Therefore, it is possible to avoid a steep acceleration in the rear of the vehicle from occurring in the entire vehicle and improve the riding comfort. In addition, according to this embodiment, even when only one wheel W of the pair of wheels W shown in FIG. 1 gets over the small protrusion on the road, the wheel W is auxiliary rotated in the traveling direction. It is possible to improve the ride comfort.

  Further, in the present embodiment, since the angle α is a relatively small angle of about 11 °, when the wheel W is rotated upward about the axis OA, the moving direction of the wheel W is: Almost upwards. For this reason, when riding on the small protrusion on the road, it is possible to give the wheel W rotation in the traveling direction and move the wheel W so as to escape upward. Therefore, it is suitable for weakening the impact force acting on the wheel W from the small protrusion. In order to achieve such an effect, the angle α is preferably in the range of 0 to 20 °.

  Next, the case where the vehicle using the rear suspension A turns will be described. FIG. 4 is a schematic diagram showing the operation at that time. When the vehicle turns and rolls, one suspension arm 2 on the outer ring side bounces and the other suspension arm 2 on the inner ring side rebounds.

  When the outer ring-side suspension arm 2 bounces in the direction Rb, the first and second rubber bushes 3A, 3B on the outer ring side and one end of the axle beam 1 are moved upward in the figure. As a result, the axial centers OA, OB of the first and second rubber bushes 3A, 3B and the axial center P at one end of the axle beam 1 move to the axial centers OAb, OBb, Pb, respectively. Due to this bounce, the axle beam 1 is twisted counterclockwise in the figure. However, the axle beam 1 has higher rigidity than the first and second rubber bushes 3A and 3B. For this reason, a force for returning the twist of the axle beam 1 is generated. This force acts on the first and second rubber bushes 3A and 3B as a moment in the direction Rb '. As described above, since the first and second rubber bushes 3A and 3B have greatly different rigidity, the first rubber bush 3A hardly deforms and the second rubber bush 3B greatly deforms in the direction N2. Cheap. For this reason, the axial center OBb moves to the axial center OBb '. As a result, the bracket 11 is rotated in the direction Rb ′ about the axis OAb. With this rotation, the axis Pb also moves to the axis Pb ′. As a result, the outer ring is moved forward by a dimension Sb1.

  Further, the moment in the direction Rb ′ in which the twist of the axle beam 1 is to be restored also acts on the suspension arm 2 via the first and second rubber bushes 3A and 3B. Due to this moment, an upward force in the figure acts on the third rubber bush 3C. The third rubber bush 3C has the lowest rigidity in the direction N3 and is easily deformed in the direction N3. For this reason, the axial center OC of the third rubber bush 3C is displaced by the dimension Lb obliquely upward and forward of the vehicle along the direction N3 and moves to the axial center Octb ″. Since the support position of the suspension arm 2 is moved by this movement, the suspension arm 2 is also moved by the dimension Lb obliquely upward and forward of the vehicle along the direction N3. As a result, the axis Pb 'of the axle beam 1 moves to the axis Pb' '. As a result, the outer ring is further moved forward by a dimension Sb2. From the above, the outer ring is moved forward by the dimension Sb.

  In the present embodiment, the angle β shown in FIG. 2 is 40 °, so that when the third rubber bush 3C receives an upward force in FIG. 4, this force is used. It is easy to displace axial center OC also in the vehicle longitudinal direction. Therefore, it is suitable for increasing the dimension Sb. Thus, in order to displace the axial center OC in the vehicle front-rear direction, the angle β is preferably in the range of 30 to 60 °.

  On the other hand, when the suspension arm 2 on the inner ring side rebounds in the direction Rr, a behavior opposite to the behavior in the case of the bouncing described above occurs. That is, the axes OA, OB, and P move to the axes OAr, OBr, and Pr along the direction Rr, respectively. Also in this case, a force for returning the twist of the axle beam 1 is generated, and a moment in the direction Rr ′ acts on the first and second rubber bushes 3A and 3B. As a result, the axis OBr moves to OBr ', and the axis Pr moves to the axis Pr'. At this time, the inner ring is moved to the rear of the vehicle by the dimension Sr1. Further, when the moment in the direction Rr ′ acts on the third rubber bush 3C, the axis OC is displaced by the dimension Lr obliquely downward in the rearward direction of the vehicle along the direction N3 and moves to the axis OCr ″. As a result, the axis Pr ′ of the axle beam is moved to the axis Pr ″. As a result, the inner ring is further moved by the dimension Sr2 toward the rear of the vehicle. As described above, the inner ring is moved rearward by the dimension Sr.

  Thus, according to this embodiment, when the vehicle turns, the outer ring is moved forward by the dimension Sb, and the inner ring is moved backward by the dimension Sr. Therefore, the axle steer characteristic of the vehicle can be set to understeer, and the operability of the vehicle can be improved.

  The rear suspension according to the present invention is not limited to the above-described embodiment. The specific configuration of the rear suspension according to the present invention can be modified in various ways.

  As a means for reducing the rigidity of the second and third rubber bushes in a certain direction, a pair of cavities are formed in each, but the present invention is not limited to such a configuration. It is good also as a structure by which the one cavity part was formed only in one with respect to the axial center of 2nd and 3rd rubber bush. Further, instead of the hollow portion, for example, a liquid sealing portion may be provided, or means such as making the spring constant of the rubber corresponding to the hollow portion smaller than the surroundings may be adopted.

1 is an overall perspective view showing an example of a rear suspension according to the present invention. It is sectional drawing which follows the II-II line | wire of FIG. It is a schematic diagram for demonstrating the effect | action of the rear suspension which concerns on this invention. It is a schematic diagram for demonstrating the effect | action of the rear suspension which concerns on this invention. It is sectional drawing which shows an example of the conventional rear suspension.

Explanation of symbols

A Rear suspension OA First rubber bush axis OB Second rubber bush axis OC Third rubber bush axis α A straight line connecting the axis of the first rubber bush and the axis of the axle beam and the first axis Angle W with the straight line connecting the axis of the rubber bush 3 and the axis of the axle beam W Wheel 1 Axle beam 11 Bracket 2 Suspension arm 3A First rubber bush 3B Second rubber bush 3C Third rubber bush 6 Side Member 32A Rubber (first rubber bush)
32B rubber (second rubber bush)
32C rubber (third rubber bush)

Claims (2)

Separated from each other in the vehicle width direction, each extends in the vehicle front-rear direction, and each front part is connected to the vehicle body so that it can swing around the front part in the vehicle height direction. A pair of suspension arms,
An axle beam extending in the vehicle width direction,
First and second rubber bushes for connecting a rear portion of each suspension arm to each end portion of the axle beam,
The rubber of the first rubber bush has a larger spring constant than the rubber of the second rubber bush,
The first rubber bush is a rear suspension that is disposed in front of the second rubber bush and the axle beam, and is disposed at a position higher than the second rubber bush. ,
The second rubber bush includes a shaft center of the first rubber bush and a shaft center of the second rubber bush arranged on the same side in the vehicle width direction out of the rigidity in a direction orthogonal to the vehicle width direction. A rear suspension characterized by having the lowest rigidity in a direction perpendicular to a straight line connecting the two. A third rubber bush for connecting the front portion of each suspension arm to the vehicle body;
The first rubber bush has a straight line connecting the axis of the axle beam and the axis of the axle beam with respect to a straight line connecting the axis of the third rubber bush and the axis of the axle beam. The rear suspension according to claim 1, wherein the rear suspension is disposed at an angle of 0 ° to 20 ° obliquely upward.

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