JPH10230723A - Torsion beam type suspension - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the productivity of a torsion beam by preventing the generation of defects such as a crack and a wrinkle at both ends of the torsion beam in a press forming time. SOLUTION: This torsion beam type suspension has a pair of trailing arms 10L and 10R which are provided separating in the lateral direction of a vehicle each other, pivoted to the car body at the front end parts, and support a wheel rotatable at the rear end parts; and a torsion beam 12 extending in the lateral direction of the vehicle, and connected to the trailing arms integrally at the both ends by welding parts 24. The torsion beam has a U-shape cross section opening rearward, the depth of the cross section is increased gradually as going to the both ends, and cuttings 22L and 22R are provided at the bottoms of the U-shape sections of both ends. The cuttings function as a stress releasing part to the drawing process at both ends of the raw material of torsion beam, in the press forming time of the torsion beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a suspension for a vehicle such as an automobile, and more particularly to a torsion beam type suspension.

[0002]

2. Description of the Related Art As one of suspensions for vehicles such as automobiles, for example, as described in Japanese Patent Publication No. 61-41768, the vehicle is laterally spaced apart from each other and pivotally supported by the vehicle body at a front end and a rear end. 2. Description of the Related Art A torsion beam type suspension having a pair of trailing arms for rotatably supporting wheels at a portion and a torsion beam extending in a lateral direction of the vehicle and connected to the pair of trailing arms by welding at both ends is conventionally known. And is used in small cars.

[0003] In a torsion beam suspension, when the left and right wheels bounce and rebound in opposite phases, the left and right trailing arms pivot up and down in opposite directions around the front end, thereby generally providing a cross-section. The U-shaped torsion beam is elastically twisted by the trailing arm and generates a force that suppresses wheel bouncing and rebounding. Therefore, a gusset as a reinforcing material is fixed to the connection part with the trailing arm, and the shape of the U-shaped cross section is set to a shape that gradually increases as the depth goes to both ends so that sufficient strength of the torsion beam is secured Have been.

[0004]

SUMMARY OF THE INVENTION
The structure in which the depth of the cross section is set to a shape that gradually increases toward both ends has the advantage that the number of parts is smaller and the step of fixing the gusset is not required as compared with the structure in which the gusset is used. is there. However, since a torsion beam having a U-shaped cross section is formed by bending a flat steel plate by press molding, the degree of drawing increases toward both ends of the torsion beam, and defects such as cracks and wrinkles occur at both ends of the torsion beam. There is a problem that it is easy and the productivity of the torsion beam is poor.

The present invention has been made in view of the above-mentioned problems in a conventional torsion beam type suspension in which the depth of a U-shaped cross section of a torsion beam is gradually increased toward both ends. The main object of the present invention is to provide a stress release portion for drawing at both ends of the torsion beam coarse material, thereby preventing defects such as cracks and wrinkles from being generated at both ends of the torsion beam during press forming, thereby producing a torsion beam. Is to improve the performance.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a main object as described above is the structure according to the first aspect, that is, a rear end portion which is spaced apart from each other in a lateral direction of a vehicle and is pivotally supported by a vehicle body at a front end portion. In a torsion beam type suspension having a pair of trailing arms for rotatably supporting wheels at a and a torsion beam extending in a vehicle lateral direction and integrally connecting the trailing arms, the torsion beam is substantially A torsion beam type wherein a U-shaped cross section is formed and the depth of the U-shaped cross section gradually increases toward both ends, and a notch is provided at both ends of the torsion beam at the bottom of the U-shaped cross section. Achieved by suspension.

According to the first aspect of the present invention, a notch is provided at both ends of the torsion beam at the bottom of the U-shaped cross section, and the torsion beam coarse material is formed into a substantially U-shaped cross section by press forming. In addition, when the drawing is performed so that the depth of the U-shaped section gradually increases toward the both ends, these notches function as stress releasing portions for the drawing at both ends of the torsion beam coarse material.
The possibility that defects such as cracks and wrinkles occur at both ends of the torsion beam is effectively reduced.

[0008]

According to a preferred aspect of the present invention, in the configuration of the first aspect, the notch is defined by a curve.

According to one preferred aspect of the present invention, in the configuration of the first aspect, both ends of the torsion beam are integrally connected to the trailing arm by welding except for a notch portion, and the edge of the notch is formed. The part is spaced from the trailing arm.

According to one preferred aspect of the present invention, in the configuration of the first aspect, the U-shaped cross section is set to have a shape that is open from the front end to the rear end of the trailing arm.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a plan view showing one embodiment of a torsion beam type suspension according to the present invention. FIG. 2 is a perspective view of the embodiment shown in FIG. FIG. 5 is an enlarged partial perspective view of the connection between the trailing arm and the torsion beam in the embodiment shown, viewed obliquely from above and forward.

In these figures, 10L and 10R denote left and right trailing arms, respectively, which are spaced apart from each other in the lateral direction of the vehicle, and 12 denotes a torsion beam extending in the lateral direction of the vehicle. Each of the trailing arms 10L and 10R is formed of a substantially S-shaped steel pipe having a circular cross section, and the torsion beam 12 has a substantially horizontal cross section U.
It is formed from a shaped steel plate.

The trailing arms 10L and 10R are fixed to the front end, respectively, and are pivotally supported on a vehicle body (not shown) by rubber bush devices 16L and 16R having axes 14L and 14R, respectively, and the bracket 1 fixed to the rear end.
Wheels (not shown) are rotatably supported around the rotation axes 20L and 20R via 8L and 18R.

In the illustrated embodiment, the U-shaped cross section of the torsion beam 12 is set so as to open from the front end of the trailing arm toward the rear end, that is, backward. Further, the depth of the U-shaped cross section of the torsion beam 12 gradually increases toward both ends, whereby the curved leading edge 12A of the torsion beam is gradually displaced forward toward both ends. The front edges at both ends of the torsion beam 12, that is, the bottom of the U-shaped cross section, have notches 22L and 2R.
2R is provided. The notches 22L and 22R have a substantially parabolic shape extending in a direction approaching each other from both ends of the torsion beam.

At both ends of the torsion beam 12, the trailing arms 10L and 10L
R are integrally connected to the notches 22L and 22R.
Edge 26 is spaced from the trailing arm.
As shown in FIG. 4, the vertical width Wn of the edges 26 of the notches 22L and 22R at both ends of the torsion beam 12 is substantially reduced because the welding torch 28 must be excessively inclined. Width W that cannot be welded
Substantially the same as w.

As shown in FIG. 5, the torsion beam 12 is a torsion beam coarse member made of a flat steel plate punched into a predetermined shape as shown in FIG. And 22R
Is formed, the torsion beam blank 30 having a notch 22L 'and 22R' corresponding to the cross section U substantially having a cross section U, for example, by hot pressing.
It is formed by forming into a shape and drawing so that the depth of the U-shaped section gradually increases toward both ends. Therefore, the torsion beam coarse material is drawn deepest at both ends.

According to the embodiment configured as described above,
Notches 22L and 22R are provided at the front edges of both ends of the torsion beam 12, and correspondingly, both ends of the torsion beam coarse material 30 which is drawn most deeply when the torsion beam is formed by press molding. Notches 22L 'and 22R' are provided, and these notches function as stress releasing portions during drawing, so that the torsion beam 12 free from defects such as cracks and wrinkles at both ends can be formed. The degree of drawing at both ends and the degree of freedom in setting the U-shaped cross-sectional shape can be increased.

In particular, according to the illustrated embodiment, the notch 22
L and 22R have a substantially parabolic shape extending in a direction approaching each other from both ends of the torsion beam 12, and the edges of the notch are stressed when the torsion beam is twisted by the trailing arms 10L and 10R. Since there are no excessively concentrated points, the strength and durability of the torsion beam 12 can be improved as compared with the case where the notch is defined by, for example, a linear edge.

Further, according to the illustrated embodiment, the notches 22L and 22L at the both edges of the torsion beam 12 are provided.
The vertical width Wn of the edge 26 of the R is substantially the same as the width Ww of the non-weldable range, so that the notches 22L and 2
Due to the fact that the edges at both ends of the torsion beam 12 are not welded to the trailing arm at the 2R portion,
The connection strength of the torsion beam to the trailing arm does not significantly decrease.

When notches 22L and 22R are not provided at both ends of the torsion beam and welding in an unweldable range is omitted, the unwelded portion acts in the same manner as a sharp notch. Since the stress concentration coefficient at the boundary between the welded portion and the unwelded portion becomes very high, and the stress concentration at this portion becomes high, it is difficult to improve the durability of the torsion beam. In contrast, according to the illustrated embodiment, the stress concentration coefficient at the boundary between the welded portion and the non-welded portion is reduced, so that the durability of the torsion beam can be improved.

In the conventional structure in which the notches 22L and 22R are not provided at both ends of the torsion beam, in order to prevent stress concentration and improve the durability of the torsion beam as described above, the All of the edges, including the curved portions at both ends, must be welded, and therefore, a device for welding while rotating the entire suspension so that the welds are in a substantially horizontal position is required. On the other hand, according to the illustrated embodiment, since welding in a range where welding is impossible is unnecessary, a device for performing welding while rotating the entire suspension is unnecessary, and therefore, the step of welding the torsion beam to the trailing arm is omitted. It can be performed inexpensively and efficiently.

Further, when the entire suspension having the conventional structure is painted by dipping in a paint bath, if the front end of the torsion beam is turned upward, the air inside the U-shaped curved portion of the torsion beam cannot be completely removed, so that the unpainted portion is not removed. When the rear end of the torsion beam is directed upward, a large amount of paint tends to accumulate inside the U-shaped curved portion of the torsion beam,
Therefore, in any case, it is difficult to paint well without rotating the suspension.

On the other hand, according to the illustrated embodiment, even when the torsion beam 12 is immersed in a paint bath with the front end thereof facing upward, the air inside the U-shaped curved portion of the torsion beam surely passes through the notches 22L and 22R. Since the suspension escapes, it is possible to paint the entire suspension satisfactorily and efficiently without requiring a large-scale device for rotating the suspension.

Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments may be included within the scope of the present invention. It will be clear to those skilled in the art that is possible.

For example, in the above-described embodiment, the notches 22L and 22R have a substantially parabolic shape extending in a direction approaching each other from both ends of the torsion beam 12, but the notches are, for example, semi-elliptical. Alternatively, it may be defined by a curve other than a parabola such as a semicircle.

In the above-described embodiment, the cross-sectional shape of the torsion beam 12 is U-shaped, but may be, for example, a semi-ellipse or a semi-circle. Although the cross section is set to have a shape that opens rearward, the opening direction of the U-shaped cross section may be set to a direction other than rearward.

In the above-described embodiment, gussets are not provided at both ends of the torsion beam 12.
For example, as shown in FIGS. 6A and 6B, gussets 32 may be provided at both ends of the torsion beam 12 and fixed to the trailing arm and the torsion beam by, for example, welding. Since the degree to which the depth of the shaped section gradually increases toward both ends may be small, the size of the notch provided at both ends of the torsion beam may be small.

In particular, if the gusset 32 also has a substantially U-shaped cross-sectional shape, the notches defined by the same curves as the notches 22L and 22R are also provided in the curved portion adjacent to the gusset trailing arm. It is preferable that air is evacuated and the paint is circulated through the notch 34 when the suspension is painted by dipping in the paint bath.

Further, when the gusset is provided as described above, the depth of the U-shaped cross section of the torsion beam 12 extends over the entire length as shown by the phantom line in FIGS. 6A and 6B. It may be substantially constant.

[0031]

As is clear from the above description, according to the present invention, notches are provided at the bottom of the U-shaped cross section at both ends of the torsion beam, and these notches are formed at both ends of the torsion beam coarse material. Since it functions as a stress release part for drawing, it is possible to effectively prevent defects such as cracks and wrinkles from occurring at both ends of the torsion beam, and to reduce the strength of connection of the torsion beam to the trailing arm. In addition, the welding of the notched portion can be omitted, and the inner surface of the U-shaped cross section of the torsion beam can be coated well by immersing the entire suspension in a paint bath. In this case, the productivity of the torsion beam can be greatly improved as compared with the case of (1).

[Brief description of the drawings]

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

FIG. 2 is a perspective view of the embodiment shown in FIG.

FIG. 3 is an enlarged partial perspective view of a connecting portion between the trailing arm and the torsion beam in the embodiment shown in FIG.

FIG. 4 is an enlarged partial side view showing a welding area between the trailing arm and the torsion beam in the embodiment shown in FIG. 1;

FIG. 5 is a plan view showing a torsion beam coarse material for forming a torsion beam before press molding.

FIG. 6 is an enlarged partial plan view showing a main part of another embodiment of a torsion beam type suspension in which gussets are provided at both ends of a torsion beam.

[Explanation of symbols]

 10L, 10R: Trailing arm 12: Torsion beam 16L, 16R: Rubber bushing device 18L, 18R: Bracket 22L, 22R: Notch 24: Welded part 30: Torsion beam coarse material 32: Gusset

Claims (1)

[Claims] 1. A pair of trailing arms spaced apart from each other in a lateral direction of a vehicle and pivotally supported by a vehicle body at a front end thereof and rotatably supporting wheels at a rear end thereof; In a torsion beam type suspension having a torsion beam integrally connecting a ring arm,
The torsion beam has a substantially U-shaped cross section, and the depth of the U-shaped cross section gradually increases toward both ends, and a notch is provided at both ends of the torsion beam at the bottom of the U-shaped cross section. A torsion beam suspension.