JPH11115430A - Suspension arm - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension arm which has a desired curbed shape and can be manufactured efficiently at a low cost. SOLUTION: This suspension arm is constituted as a trailing arm of torsion beam type suspension having a pair of trailing arms 10 which are mutually arranged at an interval in the lateral direction of a vehicle, are supported on a car body in a front end part, and support a wheel 22 rotatably in a rear end part and a torsion beam 12 which is extended in the lateral direction of the vehicle and is integrally connected to the trailing arms. The trailing arm is made of one plate material which is curved in substantially S shape due to plastic deformation and is formed like a pipe, and mutually opposing side fringes of the plate material are welded in a welded part. The welded part is positioned on more outboard side than a central axis of the trailing arm.

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 suspension arm.

[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. Conventionally, a torsion beam type suspension having a pair of trailing arms that rotatably support wheels at a section and a torsion beam extending in the lateral direction of the vehicle and connected to the two trailing arms by welding at connecting portions at both ends is conventionally known. It is more known and is used in small cars.

[0003]

In a suspension such as the above-mentioned torsion beam type suspension,
In some cases, the suspension arm must be set in a curved shape for the purpose of avoiding interference with other surrounding components. For example, in a torsion beam suspension, to reduce the rotational moment about the front end pivot received by the trailing arm from the wheel due to the longitudinal force acting on the wheel when the vehicle accelerates or decelerates, the pivot is It is preferably in front of the ground point of the wheel and the trailing arm must not interfere with the tire of the wheel. For this reason, the trailing arm may be configured to bend in an inboard direction of the vehicle at a portion close to the tire and to extend forward and outboard of the vehicle at a front end.

[0004] In general, a curved suspension arm is formed by plastically deforming a steel pipe. However, the amount of plastic deformation of the steel pipe that can be achieved without causing defects such as buckling is limited. Due to the plastic deformation, it is difficult to form the above-mentioned desired curved shape without lowering the strength. In particular, the steel pipe is plastically deformed so that the radius of curvature of the inner edge of the curved portion becomes smaller than the outer diameter of the suspension arm. Can not do.

In order to solve the above-mentioned problem, a structure in which an upper half and a lower half having a desired curved shape and a substantially semicircular cross section are welded in a state of being opposed to each other has been put to practical use. However, in the case of this structure, the two halves must be precisely machined to correspond to each other,
Also, the two halves must be welded along the two right and left welds, which makes it difficult to manufacture the suspension arm efficiently and inexpensively, and furthermore, the suspension arm must be large to ensure strength. There is a problem that does not get.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in a conventional suspension arm such as a trailing arm for a torsion beam type suspension. An object of the present invention is to provide a suspension arm which has a desired curved shape and can be efficiently and inexpensively manufactured by forming the arm.

[0007]

According to the present invention, a main object as described above is to provide a structure according to claim 1, that is, one plate is formed into a curved pipe shape by plastic deformation, and the plate members are opposed to each other. Is achieved by a welded suspension arm.

According to the first aspect of the present invention, the suspension arm is formed by forming one plate into a pipe shape curved by plastic deformation and welding the side edges of the plate facing each other. A desired curved shape is achieved by plastic deformation of the plate material, and the number of welds is reduced to one by welding only opposing side edges of the plate material, whereby the desired curved shape is obtained. The suspension arm can be manufactured efficiently and inexpensively.

According to the present invention, in order to effectively achieve the above-mentioned main object, in the configuration of the first aspect, the suspension arm has an arcuate curved portion, and the suspension arm has a curved portion. The radius of curvature of the inner edge is configured to be smaller than the outer diameter of the suspension arm.

According to the second aspect of the present invention, the suspension arm has an arcuate curved portion, and the radius of curvature of the inner edge of the curved portion is smaller than the outer diameter of the suspension arm. It is possible to increase the degree of freedom in setting the position of the end of the suspension arm on the vehicle body side while avoiding an excessive increase.

[0011]

According to a preferred aspect of the present invention, in the configuration of the first aspect, the suspension arm is configured as a trailing arm of a torsion beam type suspension (preferred aspect 1).

According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 1, the welded portions of the side edges of the plate material facing each other are located on the outboard side with respect to the center axis of the trailing arm. (Preferred mode 2).

According to another preferred embodiment of the present invention, in the configuration of the above-described preferred embodiment 2, the welded portions of the side edges of the plate material facing each other are located closest to the outboard side of the trailing arm. (Preferred embodiment 3).

According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 1, the central axis of the trailing arm is substantially in one plane, and the side edges of the plate member facing each other. Is configured to be located closest to the outboard side of the trailing arm (preferred embodiment 4).

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention applied to a trailing arm of a torsion beam type suspension will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a plan view showing the right half of an example of a torsion beam type suspension incorporating one embodiment of a suspension arm according to the present invention, and FIG.
3 is a plan view showing only the trailing arm of the embodiment shown in FIG. 3, FIG. 3 is a side view showing only the trailing arm from the outboard side of the vehicle, and FIG. 4 is an enlarged sectional view taken along line IV-IV of FIG. It is.

In these figures, reference numeral 10 denotes a trailing arm 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. The pair of left and right trailing arms 10 extend in the vehicle front-rear direction as a whole so as to be symmetrical with each other.
The torsion beam 12 is formed of a steel plate having a substantially U-shaped cross section opened backward, and a torsion bar 14 is disposed inside the torsion beam 12.

Each trailing arm 10 is pivotally supported at a front end by a toe control link 16 on a vehicle body (not shown), and rotates around a rotation axis 20 via a bracket 18 fixed to the rear end. The wheel 22 is supported as possible. A shaft 26 is fixed to a position close to the bracket 18 by a bracket 24 for mounting a shock absorber, and the shaft 26 supports a lower end of the shock absorber (not shown).

The toe control link 16 is pivotally supported at its front end by a rubber bushing device 28 about an axis 30 extending substantially in the lateral direction of the vehicle, and at its rear end by a rubber bushing device 32. A rubber bush (not shown) is pivotally supported about an axis 34 extending in the vertical direction and between the link between the rubber bushing devices 28 and 32 and the inner surface of the trailing arm. Is arranged. The front end of the trailing arm 10 may be directly connected to the outer cylinder of the rubber bush device such as the rubber bush device 28.

In the example shown, the torsion beam 1
The depth of the U-shaped cross section of the torsion beam gradually increases toward both ends, so that the curved leading edge 1
2A is gradually displaced forward toward both ends.
Both ends of the torsion beam 12 are connected to a middle portion between the front end and the rear end of the trailing arm 10 by welding portions 36 as connecting portions.

In the embodiment shown, the trailing arm 10 has a generally S-shaped curved shape such that its central axis 10A lies in one plane and has a cross-sectional shape close to a rectangle. Except for the front end, it is formed of a steel plate plastically worked into a pipe so as to have a substantially circular cross section, and is closed at the rear end with a circular steel plate. In particular, the trailing arm 10 has a curved portion 10B that is curved in an inboard direction so that it does not interfere with the tires of the wheels 22 and the front end thereof extends forward of the vehicle and in the outboard direction.

In particular, in the illustrated embodiment, as shown in FIG. 2, if the outer diameter of the trailing arm 10 is d and the radius of curvature of the inner edge of the curved portion 10B of the trailing arm is r, The radius of curvature r is set to substantially the same value as the outer diameter d. However, as described later in detail, the ratio of the radius of curvature to the outer diameter r / d may be 1 or more.
Further, it may be less than 1 in a range of 0.5 or more.

As shown in FIGS. 2 and 4, the opposite side edges 10C and 10D of the steel plate constituting the trailing arm 10 are fixed to each other by a welded portion 10E of arc welding. The side edges 10C and 10D, and thus the weld 10E, are located on the most outboard side of the trailing arm 10 and extend substantially straight as viewed from the outboard side of the vehicle.

Next, an example of a preferred manufacturing method for manufacturing the trailing arm 10 of the illustrated embodiment will be described with reference to FIG.

First, as shown in FIG. 5A, a substantially rectangular steel plate 38 having a thickness of 4 mm or less and made of high-strength steel such as JIS standard SPH590-OD is prepared.
Next, as shown in FIG. 5 (B), the steel plate 38 has a substantially U-shaped cross-sectional shape by several stages of cold pressing, and the degree of curvature of the S-shape is smaller than that of FIG. Plastically deformed into shape. In FIG. 5B, 38
A shows an elongation deformation part by press work, and 38B shows a shrinkage deformation part by press work.

Next, as shown in FIG. 5 (C), the steel sheet 38 'having an intermediate shape is deformed into a shape substantially the same as the product shape shown in FIG. 1 by several stages of cold pressing. Then, as shown in FIG. 5 (D), the opposed side edges 38C and 38D of the substantially product-shaped steel plate 38 ″ are welded by, for example, a MIG welding device 40, and furthermore, the trailing end of the trailing arm. A circular steel plate is welded to a portion corresponding to.

Table 1 below shows a case where a steel pipe is bent by plastic working, and an upper half and a lower half are formed from a steel plate by plastic working and they are integrally welded to each other (two-part system). With respect to the above-described preferred manufacturing method for forming the trailing arm having the structure described in the above, the ratio of the radius of curvature of the inner edge of the curved portion to the outer diameter of the trailing arm, r /
The relation between d and the processing limit is shown. In Table 1 below, ○ means that normal processing is possible, and × means that normal processing is impossible due to occurrence of defects such as buckling.

[0028]

[Table 1]

As can be seen from Table 1 above, when the steel pipe is bent and deformed, the ratio r / d of the radius of curvature of the inner edge of the curved portion to the outer diameter of the trailing arm is set to 1 without causing defects such as buckling. Can not be smaller. On the other hand, according to the above-described preferred manufacturing method of forming the trailing arm having the illustrated structure, the degree of freedom of the ratio of the radius of curvature to the outer diameter r / d is high, and there is no need to cause defects such as buckling. Accordingly, the ratio r / d can be made smaller than 1, so that the degree of freedom in setting the position of the front end of the trailing arm can be increased without causing a problem such as a decrease in the strength of the trailing arm. Thereby, the degree of freedom in setting the torsion beam type suspension can be increased.

In the case of the two-split system, the ratio r / d is set to 1
As shown in FIG. 6A, the upper half 50A and the lower half 50A are substantially mirror images of each other and accurately engage with each other at left and right side edges. The body 50B must be accurately formed by plastic working from an S-shaped steel plate. As shown in FIG. 6B, the upper half 50A and the lower half 50B are left and right by a welding device 52. Must be welded along the two side edges. Therefore, it is difficult to efficiently manufacture the trailing arm at low cost, and it is difficult to reduce the size and weight of the trailing arm, such as reducing the diameter of the trailing arm, due to the fatigue strength of the welded portion.

On the other hand, according to the preferred manufacturing method described above, the steel sheet may have a substantially rectangular simple shape,
Since there is only one weld, the trailing arm can be manufactured efficiently and inexpensively, and the possibility of lowering the fatigue strength is lower than in the case of the two-part system in which the weld is two places. Therefore, it is possible to reduce the size and weight of the trailing arm by reducing its thickness and diameter.

In particular, according to the illustrated embodiment, the weld 10
Since E is located closest to the outboard side of the trailing arm 10, a stress applying direction for bending the steel sheet into a pipe shape and a stress applying direction for bending the steel sheet into an S shape when pressing the steel sheet. Is at a right angle, which makes it easier and more accurate to press the steel sheet than when the weld is set at a position other than the most outboard side or the most inboard side of the trailing arm. it can.

For the above-described reason, the welded portion 10E may be set at the most inboard side of the trailing arm. In this case, the welded portion of the bracket 24 for attaching the shaft 26 for connecting the shock absorber is provided. Because of the necessity of securing the same, a non-welded portion must be set at the welding portion 10E of the trailing arm at the position of the bracket 24, and the strength of the trailing arm tends to be locally reduced.

On the other hand, according to the illustrated embodiment, both side edges of the steel plate can be welded without interruption over the entire length of the trailing arm, and good strength of the trailing arm can be secured. Since the bracket 18 for supporting the wheel 22 is much larger than the bracket 24, even if the welding for fixing the bracket 24 to the trailing arm 10 is omitted at the welded portion 10E, the mounting of the bracket 24 is performed. There is no significant decrease in strength.

Also, according to the illustrated embodiment, the central axis 10A of the trailing arm 10 lies in one plane, and the welded portion 10E is located closest to the outboard side of the trailing arm 10, thereby allowing the vehicle to move out of the vehicle. Since it extends substantially linearly when viewed from the board side, when the weld is set at a position other than the most outboard side or the most inboard side of the trailing arm or when the weld is three-dimensionally The welding process can be performed easily and well as compared with a case where the welding process is set along the displaced line.

In the illustrated suspension, when the left and right wheels 22 bounce and rebound in opposite phases to each other, the trailing arm 10 moves the center line 42 in the front-rear direction of the vehicle and the shearing center axes of the torsion beam 12 and the torsion bar 14. 44, and pivots up and down around an axis 46 connecting the intersection O1 with the center 44 of the rubber bushing device 28,
As a result, the torsion beam 12 receives a torsional moment from the trailing arm 10 at both ends, so that the trailing arm receives a force in the direction of suppressing wheel bounce and rebound due to the reaction force of the elastic deformation of the torsion beam. Is suppressed.

According to the illustrated embodiment, the welding portion 10E of the trailing arm 10 is located farthest from the welding portion 36 of the torsion beam 12, so that the welding portion 10E is formed.
Reduces the stress acting on the welded portion 10E near the torsion beam due to the reaction force of the elastic deformation of the torsion beam, thereby improving the durability of the trailing arm, as compared with the case where the torsion beam is close to the welded portion 36. Can be done.

In the above, the present invention has been described in detail with respect to a specific embodiment. However, the present invention is not limited to the above embodiment, and various other embodiments are included in 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 suspension arm is a trailing arm of a torsion beam type suspension. However, the present invention is applicable to a suspension arm of a type other than a torsion beam type suspension such as a double wishbone type suspension. May be applied.

In the above embodiment, the welded portion 1
Although 0E is set at the most outboard side of the trailing arm 10, the welded portion 10E may be set at the most inboard side of the trailing arm or at a position other than these.

In the above-described embodiment, the trailing arm 10 has a circular cross section except for the front end, but the cross section of the trailing arm may have any cross section such as an ellipse or a polygon. May be set.

[0042]

As is apparent from the above description, according to the structure of the first aspect of the present invention, a desired curved shape is achieved by plastically deforming one plate material, and the plate materials are opposed to each other. Since only the side edges are welded, the number of welds is reduced to one place, so that a suspension arm having a desired curved shape can be manufactured efficiently and at low cost, and the fatigue strength of the suspension arm can be improved. Thus, the size and weight of the suspension arm can be reduced.

According to the second aspect of the present invention, since the radius of curvature of the inner edge of the bow-shaped curved portion of the suspension arm is smaller than the outer diameter of the suspension arm, it is possible to prevent the length of the suspension arm from becoming excessively large. In addition, the degree of freedom in setting the position of the end of the suspension arm on the vehicle body side can be increased, thereby increasing the degree of freedom in designing the suspension.

[Brief description of the drawings]

FIG. 1 is a plan view showing a right half of an example of a torsion beam type suspension incorporating one embodiment of a suspension arm according to the present invention.

FIG. 2 is a plan view showing only the trailing arm of the embodiment shown in FIG. 1;

FIG. 3 is a side view of the trailing arm viewed from the outboard side of the vehicle.

FIG. 4 is an enlarged sectional view taken along line IV-IV in FIG. 2;

FIG. 5 is a process chart showing an example of a method for manufacturing the trailing arm of the embodiment.

FIG. 6 is a perspective view (A) showing an upper half and a lower half for manufacturing a trailing arm by a conventional two-piece method, and a cross-sectional view showing a welding process of the two halves.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Trailing arm 10B ... Bending part 10C, 10D ... Side edge 10E ... Welding part 12 ... Torsion beam 16 ... Toe control link 18 ... Bracket 22 ... Wheel 36 ... Welding part

Claims (2)

[Claims] 1. A suspension arm in which one plate is formed into a pipe shape curved by plastic deformation, and opposite side edges of said plate are welded. 2. The suspension arm according to claim 1, wherein the suspension arm has an arcuate curved portion, and a radius of curvature of an inner edge of the curved portion is smaller than an outer diameter of the suspension arm.