JP6887150B2 - Torsion beam suspension - Google Patents

Description

The present invention relates to a torsion beam suspension.

The torsion beam suspension is mainly used on the rear wheel side of a front-wheel drive vehicle. A torsion beam, which is a long member, is suspended between a pair of left and right trailing arms. Wheels are supported by the trailing arm, and when the left and right wheels are displaced independently due to unevenness of the road surface, the torsion beam is twisted and the left and right wheels and the trailing arm are allowed to be displaced vertically independently. To do. When the road surface becomes flat, the torsion beam returns to its original shape and returns the trailing arm and wheels to their original positions. On the other hand, when the left and right wheels are displaced in the same phase, the left and right wheels and the trailing arm swing up and down integrally.

When the torsion beam is twisted, there is a point at the center of the twist. That point is called the shear center. It is known that the position of the shear center of the torsion beam affects the steerability of the vehicle.

For example, in [0007] of Patent Document 1, when the shear center line is close to the torsion beam in the plan view of the vehicle, the fixed point at the time of torsional deformation (center point of the torsional deformation) and the trailing arm are supported with respect to the vehicle. It is described that the angle between the axis connecting the support center points and the shear axis increases. Further, it is described that when the vehicle body rolls, the camber angle of the wheel on the outer ring side of the turning motion increases in the negative direction. In addition, when the angle between the axis and the shear center line is downward in the rear view of the vehicle, the toe angle of the wheels on the outer ring side of the turning motion changes to the understeer side when the vehicle body rolls. Are listed. Then, it is described that the toe angle changes on the oversteer side when the above angle rises outward.

Further, Patent Document 2 describes that a first end section and a second end section are provided at both ends of the trailing arm. Then, it is described that the shear center line in the intermediate section of the trailing arm is lowered or raised so as not to affect the welding to the trailing arm in the first end section and the second end section. Has been done.

Japanese Patent No. 362540 Japanese Patent No. 4448540

In the torsion beam in the rear suspension device of Patent Document 1, the boundary between the left and right end portions and the central portion is bent. Therefore, when the torsion beam is formed, the work is compressed or stretched at the bent portion, and the thickness of the work tends to be uneven.

In the twisted axle suspension device of Patent Document 2, the work is stretched at an inclined portion where the twisted axle is transferred from the left and right end sections to the straight central section. Therefore, the thickness of the work tends to be uneven in the inclined portion.

If the work is leaned or stretched when forming the torsion beam, the torsion beam may be damaged by the load when using the torsion beam type suspension.

By lowering or raising the position of the shear center in the central part of the torsion beam, the desired alignment characteristics can be obtained, and the thickness of the work can be prevented from becoming excessively uneven when the torsion beam is formed. It is an object of the present invention to provide a possible torsion beam type suspension.

A trailing arm that is paired on the left and right, has a support portion for a vehicle body side member on one end side thereof, and has a wheel support portion on the other end side, and a torsion beam in which both ends thereof are supported by the trailing arm. The torsion beam type suspension is configured so that the position of the shear center in the central portion thereof is lower or higher than the position of the shear center in both end portions in the front view or the rear view of the vehicle. The shape of the torsion beam on the plane side solves the above-mentioned problems by the torsion beam type suspension, which is configured as a curved surface whose entire shape from one end side to the other end side is curved in a bow shape. Since the torsion beam is configured as a curved surface that is curved in a bow shape from one end side to the other end side, it is possible to prevent the work from being excessively thin or excessively thick. .. Therefore, when the torsion beam type suspension is used, it is possible to prevent the torsion beam from being damaged due to the difference in the thickness of the workpiece.

By lowering or raising the position of the shear center in the central part of the torsion beam, the desired alignment characteristics can be obtained, and the thickness of the work can be prevented from becoming excessively uneven when the torsion beam is formed. A possible torsion beam type suspension can be provided.

It is a top view which shows one Embodiment of a torsion beam type suspension. It is a bottom view of the torsion beam type suspension of FIG. It is a rear view of the torsion beam type suspension of FIG. It is a right side view of the torsion beam type suspension of FIG. It is sectional drawing in the AA part of FIG. It is sectional drawing in the CC part of FIG. It is a figure which shows the position of each of the cross section of the torsion beam in the BB portion in FIG. 1 and the cross section of the torsion beam in the CC portion in FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The embodiments shown below are merely examples of the embodiments of the present invention.

As shown in FIGS. 1 to 4, the torsion beam type suspension 1 of the present embodiment includes a pair of left and right trailing arms 11 and a torsion beam 12 in which both ends are fixed to the trailing arms 11. It includes a pair of reinforcement members 13 (see FIG. 5) fixed to the bottom surface side of the trailing arm 11 and the bottom surface side of the torsion beam 12. As shown in FIG. 1, the left and right trailing arms 11 and the reinforcement member 13 have a symmetrical shape with the central portion of the torsion beam 12 as a boundary.

As shown in FIG. 1 and the like, the torsion beam type suspension 1 of the present embodiment includes a wheel support portion 16 on one end side of the trailing arm 11. The support portion 16 includes a member called an end plate 17 and an axle (not shown), and the axle projects from the central portion of the end plate 17 to the left or right of the vehicle. The wheel is brought into contact with the end plate 17 in a state where the shaft hole on the wheel side is inserted into the axle to support the wheel.

As shown in FIG. 1 and the like, the other end side of the trailing arm 11 is provided with a mounting portion 18 for a vehicle body side member. In the torsion beam type suspension 1 of the present embodiment, the attachment portion 18 to the vehicle body side member is configured by incorporating a bush (not shown) made of an elastic body such as rubber in a hollow annular member 19. The trailing arm 11 and the hollow tube-shaped member 19 are joined by welding. When the torsion beam type suspension 1 is attached to the vehicle body, the shaft on the vehicle side is inserted into the hole of the bush to swingably support the trailing arm 11 with respect to the vehicle body. When a load is input to the trailing arm 11 via the wheels, the trailing arm 11 moves with respect to the vertical direction of the vehicle together with the wheels rotatably supported on the other end side around the axis on the vehicle side passed through the bush. And displace. In FIG. 7, the height of the shaft when the trailing arm 11 swings with respect to the vehicle body, that is, the height of the shaft on the vehicle side inserted through the bush is defined as “D”. Although details will be described later, in FIG. 7, the height of the shear center (shear center line) at the left and right ends of the torsion beam 12 is set to “E” in FIG. 7, and the shear center (shear center line) in the central portion of the torsion beam 12 is defined as “E”. Let the height of be "F".

As shown in FIG. 1 and the like, the trailing arm 11 has a curved shape in which the central portion is recessed in a bow shape toward the center of the vehicle in a plan view or a bottom view. As shown in FIG. 5, the trailing arm 11 has a substantially circular cross-sectional shape from one end to the other end, and is hollow from one end side to the other end side of the trailing arm 11. ing. The trailing arm 11 on the right side of the vehicle and the trailing arm 11 on the left side of the vehicle have a symmetrical shape. Since the trailing arm 11 is hollow, the torsion beam suspension 1 can be made lighter.

As shown in FIG. 7, the torsion beam 12 includes a flat plate material 121, a vehicle front side plate material 122, a vehicle rear side plate material 123, a front side plate material 121, and a rear side plate material 123, respectively. It is provided with a flange 124 projecting from the edge of the surface to the front side or the back side, and the cross section thereof is in the shape of a hat. The plate member 121 on the flat side of the torsion beam 12 is brought into contact with the protrusion of the trailing arm 11, and the opening on the bottom surface side of the torsion beam 12 is directed toward the bottom surface side of the vehicle. Is fixed. As shown in FIG. 7, the cross-sectional shape of the torsion beam 12 is smaller in the central portion of the torsion beam 12 than in both end portions. In the central portion, the plate member 122 on the front side is longer than both ends.

In the torsion beam type suspension 1 of the present embodiment, as shown in FIG. 1 and the like, a damper support portion 23 is provided inside the trailing arm 11 on one end side. The support portion 23 of the damper is a groove composed of a plate material on the bottom surface side, a plate material on the left side, and a plate material on the right side, and this groove extends toward the back surface side of the vehicle. The damper support portion 23 is provided with a total of two through holes in the left and right plate materials for supporting the shaft arranged at the end portion of the damper, and the flat side thereof is opened to receive the end portion of the damper. ..

In the torsion beam type suspension 1 of the present embodiment, the support portion 25 of the coil spring is provided between the support portion 23 of the damper and the protrusion portion arranged at the central portion of the trailing arm 11. The support portion 25 of the coil spring is composed of a plate material on the bottom surface side and a wall surface composed of a plate material protruding from the plate material on the flat surface side, and is a dish extending from the inside of the trailing arm 11 toward the center of the torsion beam 12. It is a shaped member.

In the torsion beam type suspension 1 of the present embodiment, as shown in the cross-sectional view of FIG. 6, the support portion 25 of the coil spring and the reinforcement member 13 are continuous and integrated members. This eliminates the complexity of joining the support portion 25 and the reinforcement member 13 by welding, and prevents a decrease in rigidity due to the division of the member into a plurality of parts.

In the torsion beam type suspension 1 of the present embodiment, the reinforcement member 13 is fixed so as to straddle the joint portion between the trailing arm 11 and the torsion beam 12. As shown in FIGS. 2 and 5, in the present embodiment, the base end side of the reinforcement member 13 is fixed to the bottom surface side of the trailing arm 11, and the tip end side thereof is the flat plate member 121 constituting the torsion beam 12. It is fixed to the back side of.

As shown in FIGS. 3 and 5, in the torsion beam type suspension 1 of the present embodiment, the shape of the torsion beam 12 on the flat side, in other words, the shape of the plate member 121 on the flat side is one end side thereof in front view or rear view. The entire surface from to the other end is configured as a curved surface that is curved like a bow. Then, there is no straight portion on the plane side of the torsion beam 12. Therefore, except for the contact portion 125 with respect to the trailing arm 11, which will be described later, the entire region from one end to the other end of the torsion beam 12 is curved in a bow shape toward the bottom surface side of the vehicle. Then, the central portion of the torsion beam 12 is curved so as to be closest to the bottom surface side.

As described above, since the torsion beam 12 is curved in a bow shape as a whole, it is possible to prevent a part of the work from being excessively stretched or excessively compressed when the torsion beam is formed from the work by press molding or the like. Will be done. As a result, the plate thickness of the torsion beam 12 becomes substantially uniform from one end side to the other end side. The torsion beam 12 is repeatedly twisted during use. Since the torsion beam 12 of the present embodiment has a substantially uniform plate thickness from one end side to the other end side, damage such as cracking or breaking of the torsion beam 12 is unlikely to occur.

The torsion beam 12 is formed by press-molding a flat steel plate into a shape in which the entire beam from one end side to the other end side is curved in a bow shape. When this beam shape is used, the shape of the steel plate before molding can be made substantially rectangular. If the shape of the steel sheet before forming is substantially rectangular, it is possible to suppress the generation of scraps of the steel sheet and improve the yield. On the other hand, when the torsion beam is provided with an extremely bent portion or an inclined portion, the shape of the steel plate before forming cannot be made substantially rectangular. In such a case, a large amount of scraps of the steel sheet will be generated, and the yield will decrease.

In the torsion beam type suspension 1 of the present embodiment, as shown in FIG. 7, the shear center (F) at the central portion of the torsion beam 12 is higher than the height of the shear center (E) at the left and right ends of the torsion beam 12. The height is low. The heights of the shear center (E) at the left and right ends and the shear center (F) at the central portion (fixed point) are higher than the bush shaft (D). This makes it easier to change the toe angle on the turning outer ring side in the toe-out direction compared to the case where the shear center (F) in the central portion is not lowered with respect to the shear center (E) at the left and right ends, resulting in oversteer. The tendency is relatively high to realize good steering characteristics.

In the torsion beam type suspension 1 of the present embodiment, the contact portion 125 with respect to the trailing arm 11 is not configured to be curved in a bow shape together with the torsion beam 12. However, the contact portion 125 may also be configured to be curved in a bow shape together with the torsion beam 12 according to the depth at which the torsion beam 12 is curved.

The contact portion 125 is a projecting piece having a shape along the outer shape of the trailing arm 11. By arranging the abutting portions 125 at both ends of the torsion beam, the torsion beam 12 can be firmly fixed to the trailing arm 11 without rattling.

In the torsion beam type suspension 1 according to the above embodiment, the shape of the torsion beam 12 on the plane side is curved in a bow shape toward the bottom surface side of the vehicle in the entire region from one end to the other end of the torsion beam 12 in front view or rear view. I tried to do it. This embodiment is modified so that the shape of the torsion beam on the flat side is curved in a bow shape from one end to the other end of the torsion beam in front view or rear view. You may. In this case, the position of the shear center at the center of the torsion beam is higher than the position of the shear center at both ends of the torsion beam. By doing so, the toe angle on the turning outer ring side can be easily changed in the toe-in direction as compared with the case where the shear center of the central portion is not raised, the understeer tendency is relatively high, and good steering characteristics are obtained. It can be realized.

1 Torsion beam suspension 11 Trailing arm 12 Torsion beam 16 Wheel support 18 Support for vehicle body side member F Shear center at the center E Shear center at both ends

Claims (1)

A trailing arm that is paired on the left and right, has a support for the vehicle body side member on one end side, and has a wheel support on the other end side.
A torsion beam type suspension having a trailing arm with a torsion beam whose both ends are supported.
The torsion beam is configured such that the position of the shear center in the central portion thereof is lower or higher than the position of the shear center in both end portions thereof in the front view or the rear view of the vehicle.
Planar side of the shape of the torsion beam state, and are not whole leading to the other end from the one end is configured as a curved surface which is curved in a bow shape,
In the torsion beam, a flat side plate having a flat portion, a front plate, a back plate, and a flange protruding from the edge of the front plate and the back plate to the front or back side are continuous. However, the torsion beam type suspension has an arcuate cross-sectional shape in which the flat side plate material and the back side plate material are continuous and the flat side plate material and the front side plate material are continuous.

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