JP2001039135A - Torsion beam type suspension - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability by smoothing the stress change along the extending direction at both end parts of a torsion beam. SOLUTION: At both end parts of a torsion beam 6, a section changing point P is set at the inward of an end part of a first reinforcement 7 in the vehicle width direction. The sectional shape on a trailing arm 1 side is substantially V-shaped by increasing the curvature of a top part on one side of the changing point P, while the sectional shape on a center part side in the vehicle width direction is formed substantially U-shaped by squeezing the top part 6a to relatively increase the curvature of the top part 6a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a torsion beam suspension for a vehicle.

[0002]

2. Description of the Related Art In a conventional torsion beam type rear suspension, for example, both ends of a torsion beam 6 extending in the vehicle width direction are rigidly connected to side surfaces of a trailing arm 1 as shown in FIG. . In this torsion beam type suspension, since the up and down movement of the wheels in the left and right opposite directions is generated by the torsion of the torsion beam 6, the roll rigidity can be adjusted by the torsion beam 6.

[0003] The torsion beam 6 generally has an open cross-sectional shape having a substantially U-shaped cross-section, and has the same cross-section along the extending direction. Note that the opening direction of the opening cross section is set to be downward, forward of the vehicle, or the like. In general, the reinforcements 7 and 8 (reinforcing members) are arranged at both ends of the torsion beam 6 so as to have high rigidity.

[0004]

When the vehicle body rolls, a torsion is generated in the torsion beam 6, and a required stress is applied to the joint of the torsion beam 6 and the trailing arm 1. In addition, even when the trailing arm 1 receives a longitudinal force, a required stress is applied to the joint.

At this time, since the portions reinforced by the reinforcements 7 and 8 are set to have relatively high torsional rigidity, the stress value increases without being twisted much, but in the direction away from the trailing arm 1. When viewed along, the stress value sharply decreases in a step-like manner at the boundary of the end point of the reinforcement 7 (see the symbol Q in FIG. 7). FIG. 7 illustrates a case where two types of reinforcements 7 and 8 are arranged.

Here, since the torsion of the torsion beam 6 is input in a reciprocating manner, the amount of change in the stress at the position where the stress at the end point Q of the reinforces 7, 8 changes in a stepwise manner. The larger the torsion beam 6, the more disadvantageous in durability at both ends. If the thickness of the entire torsion beam 6 is increased to prevent this, the weight of the torsion beam 6 may become unnecessarily heavy.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an object to improve the durability by smoothing a change in stress along the extending direction at both ends of a torsion beam. .

[0008]

In order to solve the above-mentioned problems, the invention described in claim 1 of the present invention comprises a pair of arms arranged on both sides in the vehicle width direction, and a pair of arms extending in the vehicle width direction. A torsion beam suspension having a torsion beam having an open cross-section having a substantially U-shaped or substantially V-shaped cross-section connecting the pair of arms with each other, wherein both ends of the torsion beam are separated from the joint with the arm. The cross-sectional shape is changed in one stage or in multiple stages.

It is preferable to change the cross-sectional shape in one step or multiple steps by changing the thickness or the like so that the torsional rigidity decreases in the direction away from the joint with the arm. Next, according to a second aspect of the present invention, in the configuration of the first aspect, the change of the cross-sectional shape is such that the curvature of the top in the open cross-section is set smaller as the distance from the joint with the arm increases. It is characterized by the following.

Next, a third aspect of the present invention is a torsion beam type suspension in which a connecting portion between a torsion beam and an arm is reinforced by a reinforcing member with respect to the configuration described in the first or second aspect. The change point of the cross-sectional shape is set on the inner side in the vehicle width direction from the arrangement position of the reinforcing member. Next, according to the invention described in claim 4, in the configuration described in claim 3, the cross-sectional shape is changed in one step, and the cross-sectional shape on the arm side is substantially V-shaped with the change point as a boundary. And a substantially U-shape on the inside in the vehicle width direction.

[0011]

According to the first aspect of the present invention, the cross-sectional shape of the torsion beam is changed in one step or in multiple steps along the extending direction, so that the torsion beam has one step in the extending direction. Alternatively, the torsional rigidity changes in multiple stages, the stress change points along the extending direction increase by the amount of the shape change in one stage or multiple stages, and the stress changes are dispersed, and the stress at each stress change point The amount of change can be kept small.

In this case, when the invention according to claim 2 is adopted, the curvature of the top portion in the open cross section is set to be smaller as the distance from the joint with the arm increases, so that the torsional rigidity increases as the distance from the joint with the arm increases. It is set so as to be gradually lowered gradually, and there is an effect that the change in stress at each cross-sectional shape change point is gradually reduced stepwise, that is, the change in stress value is smooth.

Moreover, since the curvature of the top of the cross section is merely changed, the processing is easy. Next, in the invention according to claim 3, there is an effect that the change in stress is the largest, that is, the change in stress at the end point of the reinforcing member farthest from the arm can be set to be small. At this time,
When the invention according to claim 4 is adopted, the curvature of the top of the cross section on the arm side is set to be large at a point where the cross-sectional shape is changed, thereby providing the effect of the invention according to claim 3. In addition, since only the shape of the top of the torsion beam is changed, the processing is easy.

[0014]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a torsion beam type rear suspension according to the present embodiment,
FIG. 2 is a side view as viewed from the outside in the vehicle width direction. In the suspension according to the present embodiment, as shown in FIG. 1, trailing arms 1 are arranged on both sides in the vehicle width direction.
Each trailing arm 1 extends in the front-rear direction of the vehicle, has a front end connected to a vehicle body-side member (not shown) via a bush 2 so as to be able to swing up and down, and has a wheel support member at the rear end. 3 and a lower portion of the shock absorber 4 are arranged. Reference numeral 5 denotes a bracket on which a lower portion of the suspension coil is arranged.

The pair of trailing arms 1
Are connected by a torsion beam 6 extending in the vehicle width direction. The torsion beam 6 has an open cross-sectional shape having a substantially U-shaped cross-section, and is open downward.
Both ends of the torsion beam 6 are, as shown in FIG.
Each is welded to the trailing arm 1 in a state where it is abutted against the inner surface. Both ends of the torsion beam 6 are reinforced by a first reinforcement 7 disposed inside the torsion beam 6 and a second reinforcement 8 disposed on the side surface of the torsion beam 6. In addition, although the case where the end of the first reinforce is located more distally than the trailing arm 1 compared to the end of the second reinforce is illustrated, the present invention is not limited to this. Further, the shape and arrangement of the reinforcement are not limited thereto, and may be any of other known shapes.

Then, the torsion beam 6 of the present embodiment
In such a case, the cross-section change point P is set at a position inside the end of the first reinforcement 7 in the vehicle width direction, and the cross-sectional shape along the extension direction of the torsion beam 6 is changed by one step. You have set. That is, the cross-sectional shape of the trailing arm 1 side with the change point P as a boundary is substantially V-shaped by reducing the curvature of the top 6a as shown in FIG.
As shown in FIG. 5, the cross-sectional shape of the central portion in the vehicle width direction is processed into a substantially U-shape by relatively increasing the curvature of the top portion 6a by crushing the top portion 6a.

The cross-sectional shape of the torsion beam 6 in the middle in the extending direction is set to the same shape as that of FIG.
In the suspension having the above-described configuration, the torsional rigidity of both ends of the torsion beam 6 connected to the trailing arm 1 is equal to the above-mentioned 2 along the extending direction of the torsion beam 6.
Position where there are two reinforces 7 and 8, position where only the first reinforce 7 is present, position where there is no reinforce 7 and 8 and the cross-sectional shape is substantially V-shaped, and there is no reinforce 7 and 8 and the cross-sectional shape is substantially U It gradually decreases in the order of the letter-shaped position.

Therefore, when the torsion beam 6 is twisted by the rolling of the vehicle body, the stress at both ends of the torsion beam 6 is as shown in FIG.
As shown in the figure, the end position R of the second reinforce 8, the end position Q of the first reinforce 7, and the cross-sectional shape change point P from the trailing arm 1 side along the extending direction.
Gradually become smaller in three stages, and each stress change point R, Q,
The stress change at P is alleviated, and particularly the stress change at the end Q of the reinforce where the stress change is large is alleviated, and the durability of the torsion beam 6 is improved without taking measures such as increasing the wall thickness.

Here, in the above-described embodiment, only one point of change in the cross-sectional shape of the torsion beam 6 along the extending direction is set, and the stress change point due to the change in the cross-sectional shape is set to one stage. Two or more steps of changing the cross-sectional shape may be set along the direction. In this case, as the distance from the trailing arm 1 increases, the curvature of the top portion 6a of the cross section at the center portion in the vehicle width direction may be set to be larger at each change point. By setting in this way, the stress change points due to the cross-sectional shape are set in a stepped manner by the number of change points, and the stress change along the extending direction of the torsion beam 6 can be set more smoothly. At this time, the cross-sectional shape change point may be set at a position where the reinforces 7 and 8 are located.
8, the rigidity is set high, so that it is not very effective.

Further, in the above embodiment, the case where the reinforcement is provided by the reinforcements 7 and 8 is described as an example. However, both ends of the torsion beam 6 not reinforced by the reinforcements 7 and 8 are provided. Is also applicable. Also,
In the above embodiment, the case where the opening direction of the open section of the torsion beam 6 is directed downward is illustrated, but the opening direction of the open section may not be downward, such as in the vehicle front-rear direction.

Further, in the suspension of the above embodiment, the torsion beam 6 is connected to a position halfway in the direction in which the trailing arm 1 extends. However, the present invention is not limited to this. May be connected to the torsion beam 6.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a torsion beam type suspension according to an embodiment of the present invention.

FIG. 2 is a side view showing a torsion beam type suspension according to an embodiment of the present invention.

FIG. 3 is a plan view showing a structure of a coupling portion to a trailing arm in a torsion beam according to an embodiment according to the present invention.

FIG. 4 is a sectional view taken along the line AA in FIG. 3, showing a sectional shape on the trailing arm side according to the embodiment according to the present invention.

5 is a sectional view taken along the line BB in FIG. 3, showing a sectional shape on the trailing arm side according to the embodiment according to the present invention.

FIG. 6 is a diagram showing a stress distribution at an end of a torsion beam according to an embodiment according to the present invention.

FIG. 7 is a diagram showing a stress distribution at an end of a torsion beam in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Trailing arm 6 Torsion beam 6a Top 7, 8 Reinforce P Section change point

Claims (4)

[Claims] 1. A pair of arms arranged on both sides in the vehicle width direction, and extending in the vehicle width direction to connect the pair of arms to form an open section having a substantially U-shaped or substantially V-shaped cross section. A torsion beam type suspension including a torsion beam, wherein a cross-sectional shape of each end of the torsion beam is changed in one step or in multiple steps in a direction away from a joint with an arm. 2. The torsion beam type suspension according to claim 1, wherein the change in the cross-sectional shape is such that the curvature of the top in the open cross-section is set to be smaller as the distance from the joint with the arm increases. 3. A torsion beam type suspension in which both end portions of a torsion beam are reinforced by reinforcing members, respectively, wherein a change point of the cross-sectional shape is set inside a vehicle width direction from an arrangement position of the reinforcing member. The torsion beam type suspension according to claim 1 or 2, wherein 4. The method according to claim 1, wherein the cross-sectional shape is changed in one step, and the cross-sectional shape on the arm side is substantially V-shaped and the inside in the vehicle width direction is substantially U-shaped at the change point. The torsion beam suspension according to claim 3.