JP3463466B2 - Twist beam suspension - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle suspension, and more particularly to a twist beam type suspension.

[0002]

2. Description of the Related Art Conventionally, as a vehicle suspension, for example, a twist beam type suspension as disclosed in Japanese Utility Model Laid-Open No. 59-109507 is known.
The conventional twist beam suspension described above includes a trailing arm, a twist beam, and a stabilizer. Trailing arms are provided for the left and right wheels respectively. An end of the trailing arm on the vehicle front side is rotatably supported by the vehicle body, and wheels are attached to the other ends.

The twist beam is a member having a U-shaped cross section and extends in the vehicle body width direction to connect the trailing arms to each other. Since the twist beam has a U-shaped cross section, the twist beam is likely to be twisted and deformed. As a result, the trailing arms can rotate in opposite directions, and therefore the left and right wheels can stroke in opposite phases.

The stabilizer is a rod-shaped or tubular member, and is arranged so as to extend linearly inside the twist beam. Both ends of the stabilizer are fixed to a twist beam or a trailing arm by welding or the like. By providing the stabilizer, the torsional rigidity of the twist beam is reinforced. As a result, rolling that occurs in the vehicle is suppressed.

[0005]

When the left and right wheels make strokes of opposite phases and the twist beam is twisted and deformed, a shear strain is generated in the twist beam about the shear center of the twist beam. Rotational displacements in opposite directions centering on the shear center occur at both ends of the.

In the conventional twist beam type suspension described above, the stabilizer linearly extends inside the twist beam as described above, and is fixed to both ends of the twist beam or the trailing arm at both ends thereof. Therefore, the connecting point of the stabilizer to the twist beam or the trailing arm is located inside the U-shaped cross section of the twist beam. Generally, the shear center of a longitudinal member having a U-shaped cross section lies on the closed side (generally outside) of that cross section. Therefore, in the conventional twist beam suspension described above, the connecting portion between the stabilizer and the twist beam is provided at a position apart from the shearing center of the twist beam. For this reason, when the twist beam is twisted and deformed, rotational displacements are generated in the connecting portions with the stabilizers at both ends of the twist beam in different directions about the shear center.
As a result, a load is applied to these connecting portions in the tension direction of the stabilizer, material fatigue or the like occurs at the connecting portions, and the durability of the twist beam suspension is reduced.

The present invention has been made in view of the above points, and suppresses the load generated at the connecting portion between the stabilizer and the twist beam or the trailing arm when the twist beam is twisted and deformed. It is an object of the present invention to provide a twist beam type suspension having improved durability.

[0008]

A twist beam type suspension according to claim 1 of the present invention has a twist beam having an open cross-sectional shape and connecting trailing arms,
In a twist beam type suspension comprising both ends of the twist beam or a stabilizer connected to the trailing arm, the stabilizer has a main body portion along a longitudinal direction of the twist beam.
And arranged so as to extend inside the twist beam, so that the connecting portion of the stabilizer and the twist beam or the trailing arm approaches the shearing central axis of the main part of the twist beam, Both ends are bent toward the central axis of shearing. In this configuration, the “open cross-sectional shape” is, for example, a U-shaped, V-shaped, or U-shaped cross-sectional shape, and the “main body portion” of the stabilizer and the twist beam refers to both end portions of each element. It shall refer to the removed part . Also books
Twist beam type suspension according to claim 2 of the invention
Is a twist beam type suspension according to claim 1.
The front of the vehicle on both ends of the main part of the twist beam
The side surface is curved toward the front of the vehicle, and the curved bay
A configuration is adopted in which a connecting portion of the stabilizer is provided in the curved portion.
According to this configuration, the connecting portion is connected by the shear central axis.
You can get closer.

In the present invention, when the twist beam is twisted and deformed, a relative rotational displacement occurs about each shear beam center in each cross section of the twist beam. Therefore, due to the twisting deformation of the twist beam, a relative rotational displacement around the shearing center is generated between both ends of the twist beam. Such a relative displacement amount is smaller in a region closer to the shear center. In the present invention, both ends of the stabilizer are bent toward the central shear axis of the main part of the twist beam. Therefore, the connecting portion between the stabilizer and the twist beam or the trailing arm is brought close to the shearing center axis of the main body portion of the twist beam, and thereby the relative portion between the connecting portion between the stabilizer and the twist beam or the trailing arm is increased. Displacement is suppressed.
As a result, the load acting on the connecting portion between the stabilizer and the twist beam or the trailing arm due to the twist deformation of the twist beam is reduced.

[0010]

FIG. 1 is a perspective view of a twist beam type suspension according to an embodiment of the present invention as seen obliquely from the front of a vehicle. 1, a pair of left and right trailing arms 20 and 22 rotatably support wheels 24 and 26 at their vehicle rear (upper right side in FIG. 1) end portions, respectively. Wheel 24 is the right rear wheel of the vehicle and wheel 26 is the left rear wheel of the vehicle. The other ends of the trailing arms 20 and 22 have rubber bushes 28 and 3 respectively.
It is connected to a vehicle body (not shown) so as to be rotatable in the up-down direction via joints 32 and 34 each including 0. The pivot axes of the trailing arms 20 and 22 are provided so as to be coaxial with each other and in the width direction of the vehicle.

The intermediate portions of the trailing arms 20 and 22 are connected to each other by a twist beam 36.
The twist beam 36 is a longitudinal member having a U-shaped cross-sectional shape that opens toward the rear of the vehicle. Further, the trailing arms 20 and 22 are connected to the vehicle body via shock absorbers 38 and 40 on the inner side of the wheel 24 and 26 mounting portions. Furthermore, the trailing arm 20
Coil springs 42 and 44 are arranged between the connection portions of the twist beam 36 and the connection portions of the shock absorbers 38 and 40 of FIGS. Further, the stabilizer 46 shown by a broken line in FIG. 1 is a tubular member, and extends along the longitudinal direction of the twist beam 36.
6 is arranged so as to extend inside. The stabilizer 46 is connected to both ends of the twist beam 36 at both ends thereof. FIG. 2 shows a trailing arm 2
It is the figure which looked at the connection part of 0 and the twist beam 36 from the vehicle upper part. In FIG. 2, the upper side corresponds to the front of the vehicle. In addition, in FIG. 2, a twist beam 36 described later is shown.
The shear center of is shown by the chain double-dashed line. In addition, FIG.
FIG. 3 is a cross-sectional view taken along line III-III in FIG. The trailing arm 22 and the twist beam 3
The connecting portion with 6 has the same configuration as that in FIG.

As shown in FIG. 2, the twist beam 36 is
Both ends are welded to the trailing arms 20 and 22 with the trailing arms 20 and 22 sandwiched from above and below, so that they are connected to the trailing arms 20 and 22. Further, the twist beam 36 has a surface on the vehicle front side curved at both ends thereof toward the vehicle front. As a result, the area of the welding surface between the twist beam 36 and the trailing arms 20, 22 is increased, and the connection strength of these members is enhanced.

As shown in FIG. 2, both ends of the stabilizer 46 are curved toward the front of the vehicle. Also, FIG.
As shown in FIG. 6, the stabilizer 46 includes sleeves 46a provided at both ends thereof perpendicularly to the longitudinal direction, and the sleeves 46a are provided at the frontmost portions of the vehicle of the curved portions at both ends of the twist beam 36. By being fastened with the nut 50, the twist beam 36 is connected. Since both ends of the stabilizer 46 are curved toward the front of the vehicle, as shown in FIGS. 2 and 3, the main body portion between the both ends of the stabilizer 46 (that is, the vehicle front end and the vehicle rear end of the twist beam 36). The portion where the and are parallel to each other) is located inside the twist beam 36 at the rear portion of the vehicle, whereas the connecting portion of the stabilizer 46 to the twist beam 36 is located at the front side of the twist beam 36. It is located in the part. As will be described later, the shearing center of the twist beam 36 is located ahead of the twist beam 36 itself in the vehicle. Therefore, since the stabilizer 46 is curved toward the front of the vehicle, the stabilizer 46 is
The connection part of the twist beam 36 to the twist beam 3 is
It means that the shear center of 6 is approached. in this case,
As described above, the surfaces on the vehicle front side at both ends of the main body portion of the twist beam 36 are curved toward the vehicle front, and the stabilizer 46 is connected to the curved portion, so that the connecting portions of these members are provided further on the vehicle front side. Thereby, the connecting portion can be brought closer to the shearing center of the twist beam 36.

According to the structure of the twist beam type suspension described above, when the in-phase stroke is generated in the wheels 24 and 26, the shock absorbers 38 and 40,
Also, the strokes of the wheels 24 and 26 are absorbed by the coil springs 42 and 44 expanding and contracting in phase. In this case, the twist beam 36 and the stabilizer 4
When 6 is displaced following the rotation of the trailing arms 20 and 22, the twist beam 36 and the stabilizer 46 are not deformed.

On the other hand, when the wheels 24 and 26 have strokes in opposite phases to each other, the shock absorbers 38 and 40 and the coil springs 42 and 44 expand and contract in opposite phases, and the trailing arms 20 and 24 are separated from each other. By rotating in the opposite direction, the stroke of the wheels 24, 26 is absorbed. In this case, both ends of the twist beam 36 are rotated in opposite directions, and the twist beam 36 and the stabilizer 46 are twisted and deformed about their longitudinal axes. Since the stabilizer 46 is a tubular member, its torsional rigidity is relatively large. Therefore, the stabilizer 46 twists and deforms together with the twist beam 36, so that the wheel 2
The reverse phase strokes 4 and 26 are suppressed, and thus rolling of the vehicle is suppressed.

By the way, in general, when a longitudinal member having a uniform cross-sectional shape undergoes torsional deformation about the longitudinal axis, shear deformation centering on the shearing center occurs between the cross-sections of the longitudinal member, and Relative rotational displacement of Therefore, a larger relative displacement occurs in a portion having a larger distance from the shear center in the cross section. The shear center of a member having a U-shaped cross-section, such as the twist beam 36, is located on the outer side of the closing side on the axis of symmetry of the U-shaped cross section. Therefore, when the twist beam 36 is twisted and deformed, a larger relative displacement is generated between the both ends of the twist beam 36 in a portion closer to the opening side end of the U-shaped cross section.

FIG. 4 shows how the two end portions are displaced when the longitudinal member having a U-shaped cross section is torsionally deformed. As shown in FIG. 4, a relative rotational displacement about the shearing center O occurs between the both ends of this member. For this reason,
As shown by the reference signs A and A ′ in FIG. 4, at the portion closest to the shear center O, that is, at the bottom of the U-shaped cross section on the closed side, the relative displacement between the two ends is relatively small, while the reference sign B ,
As shown by the addition of B ', at the site away from the shear center O,
The relative displacement between both ends is as large as d2.

As described above, the stabilizer 46 has its both ends fixed to both ends of the twist beam 36. Therefore, if the connecting portion between the stabilizer 46 and the twist beam 36 is provided at a position apart from the shearing center of the twist beam 36, if twisting deformation occurs in the twist beam 36, both end portions of the twist beam 36 Along with the relative displacement between them, large relative displacements in opposite directions occur in these connecting portions. In this case, twist beam 3
Even if the twisting deformation occurs in 6, the distance between both ends of the twist beam 36 does not change. Therefore, the distance in the vehicle body width direction between the connecting portion between the stabilizer 46 and the twist beam 36 does not change. The distance between the connecting portions of the stabilizer 48 and the stabilizer 48 increases. Therefore, as the twist beam 36 is twisted and deformed, the stabilizer 46 is twisted and stretched and deformed, and a twisting load and a tensile load are applied to the connecting portion between the twist beam 36 and the stabilizer 48. Repeated application of such a load causes fatigue and loosening of the bolts at the joint between the twist beam 36 and the stabilizer 46, which is a disadvantageous structure in terms of durability. Also, when the twist beam 36 and the stabilizer 46 are connected by welding,
The repeated load acting on the welded portion has a disadvantageous structure in terms of durability as in the case of bolt tightening.

On the other hand, in the present embodiment, as described above, both ends of the stabilizer 46 are placed in front of the vehicle body, that is,
By bending the twist beam 36 toward the shear center side, the connecting portion between the stabilizer 46 and the twist beam 36 is provided near the shear center of the twist beam 36. Therefore, the amount of relative displacement between these connecting portions is reduced, and thereby the tensile force acting on the connecting portion is suppressed. Therefore, according to this embodiment, it is possible to prevent the bolts from being damaged or loosened in the connecting portion between the stabilizer 46 and the twist beam 36, and it is possible to realize a twist beam suspension having excellent durability. .

When a tensile load due to the torsional deformation of the twist beam 36 acts on the stabilizer 46, a load directed inward of the vehicle acts on the trailing arms 20 and 22. Due to such a load, the trailing arms 20 and 22 are deformed toward the inside of the vehicle body. FIG. 5 shows a state in which the trailing arms 20 and 22 are deformed by broken lines. Note that FIG. 5 shows a state viewed from above the vehicle. As shown in FIG. 5, when a load is applied to the trailing arms 20 and 22, the trailing arms 20 and 22 are connected to the vehicle body at their front end portions. Deflection is generated toward the side. Therefore, the wheel 2
Nos. 4 and 26 tend to toe out, and the running stability of the vehicle may not be desired.

On the other hand, in this embodiment, since the tensile load acting on the stabilizer 46 is suppressed as described above, the deformation of the trailing arms 20 and 22 is suppressed. Therefore, according to this embodiment, the wheels 24 and 26 are prevented from having a toe-out tendency even when the strokes of the opposite phases occur in the wheels 24 and 26,
The desired running stability is obtained.

When the twist beam 36 is twisted and deformed, the shear strain generated in the cross section of the twist beam 36 becomes maximum at the portion farthest from the shear center, that is, at the open end of the U-shaped cross section. It becomes the minimum at the portion closest to the shear center, that is, at the bottom on the closed side of the U-shaped cross section. Therefore, the stress caused by the twisting deformation of the twist beam 36 is also U
It becomes maximum at the open side end of the U-shaped cross section and becomes minimum at the closed side bottom of the U-shaped cross section. Therefore, if the stabilizer 46 is fixed near the open end of the twist beam 36, the stress due to the torsional deformation of the twist beam 36 and the stabilizer 4 may be increased.
6 and the stress caused by the load acting on the connecting portion between the twist beam 36 are superposed and the stress becomes excessive, which is a disadvantageous structure in terms of durability of the twist beam 36.

On the other hand, in this embodiment, as described above, the twist beam 36 has the U of the stabilizer 46.
It is connected to the closed bottom part of the V-shaped cross section, that is, in the vicinity of the site where the stress due to the torsional deformation is minimum. For this reason, the stress is prevented from becoming excessive as described above, and thus the durability of the twist beam 36 is improved.

In the above embodiment, the stabilizer 46 is arranged inside the twist beam 36 over the entire length thereof, but the present invention is not limited to this, and the space between both ends of the stabilizer 46 is not limited to this. It is also possible to dispose the intermediate portion of the outside of the twist beam 36 and to provide only the connecting portion to the twist beam 36 near the shearing center of the twist beam 36. In this case, even if the position of the intermediate portion of the stabilizer 46 is changed, the torsional rigidity of the entire stabilizer 46 does not change significantly, and therefore,
It does not affect the suspension characteristics.

Further, the stabilizer 46 may have a shape which is not arranged inside the twist beam depending on the positional relationship between the arrangement position and the shearing center of the twist beam 36. That is, both ends (on the side of the connecting point) may be bent toward the shearing central axis of the main body of the twist beam.

Further, the stabilizer 46 does not have to be tubular and may be rod-shaped. In addition, the stabilizer 46
May be connected to the trailing arms 20 and 22 instead of being connected to the twist beam 36. In that case, a configuration in which a bracket protruding from the trailing arms 20 and 22 to the twist beam 36 is arranged can be considered.

In the present embodiment, the twist beam 36 having a cross section that opens toward the rear of the vehicle has been described, but the present invention is not limited to this, and may have a cross section that opens in the vertical direction or the front. That is, as long as the connecting point of the stabilizer is arranged near the cross-section closing side of the twist beam (that is, near the shearing center of the main body portion), the vertical direction or the front-back direction does not matter.

[0028]

As described above, according to the present invention, it is possible to suppress the load acting on the connecting portion between the stabilizer and the twist beam or the trailing arm when the twist beam is twisted and deformed. As a result, the durability of the twist beam type suspension can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a twist beam type suspension, which is an embodiment of the present invention, seen obliquely from the front of a vehicle.

FIG. 2 is a view of a connecting portion between a stabilizer and a twist beam of the twist beam type suspension according to the present embodiment, as viewed from above the vehicle.

FIG. 3 is a cross-sectional view taken along a line III-III shown in FIG.

FIG. 4 is a diagram showing displacement of both ends when a longitudinal member having a U-shaped cross section is twisted and deformed.

FIG. 5 is a diagram showing a state in which a wheel has a toe-out tendency due to a tensile load acting on a stabilizer.

[Explanation of symbols]

20,22 Trailing arm 36 twist beam 46 Stabilizer

Claims (2)

(57) [Claims] 1. A twist beam suspension having an open cross-sectional shape, comprising a twist beam for connecting a trailing arm, and a stabilizer connected at both ends to the twist beam or the trailing arm, wherein the stabilizer is , Its body portion extends inside the twist beam along the longitudinal direction of the twist beam
In such a manner that the connecting portion between the stabilizer and the twist beam or the trailing arm approaches the shearing central axis of the main body portion of the twisting beam, both ends of the stabilizer are set to the shearing central axis. A twist beam type suspension characterized by being bent toward. 2.The twist beam type suspe according to claim 1.
Option, Surfaces on the vehicle front side at both ends of the main part of the twist beam
Is curved toward the front of the vehicle, The stabilizer connecting portion is provided on the curved portion.
Twist beam type suspension characterized by that.