JPH01223092A - Rear arm for motorcycle - Google Patents

Abstract

PURPOSE:To obtain a rear arm with high rigidity by constituting at least the cross member section of the body section of a rear arm with an extruded material or a drawn material in the car width direction, covering the right and left openings with the right and left arm sections, and welding and fixing both of them. CONSTITUTION:A vertically swayable rear arm 8 pivotally supporting a rear wheel at its rear end section is constituted of a pair of the right and left arm sections 10, a body section 11 connecting front ends of both arm sections 10, and a pivot tube 12 fixed to the front end of the body section 11. The arm sections 10 are constituted by facing and welding respective openings of a pair of an outside member 10a and an inside member 10b molded with a plate material made of a light alloy such as an aluminum alloy into a U-shaped cross section area. In the body section 11, a cross member 14 and a pair of reinforcing sections 15a and 15b extended to the front of a car body from the upper and lower edges are formed by the extrusion molding of a light alloy. The arm sections 10 are put so as to block the right and left openings, and both of them are welded and fixed to constitute the rear arm 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rear arm of a motorcycle, and particularly to improving the rigidity of a body portion.

[Conventional technology]

Conventionally, in a motorcycle, a rear arm is pivotally supported by a body frame so as to be able to swing up and down, and a rear wheel is rotatably supported at the rear end of the rear arm. This rear arm has a body part that connects the front ends of a pair of left and right arm parts that pivotally support the rear wheel, and a pivot part that is pivotally supported by the vehicle body frame at the front end of the body part. It is composed of In such a rear arm, since a large load is particularly applied to the body portion, it is important to improve the rigidity around the body portion. Therefore, various structures have been proposed to improve the rigidity of this part. For example, as described in Japanese Utility Model Application Publication No. 60-52194, the left and right arms are pushed out, Some models are constructed from drawn parts, and the body is constructed from an integrally cast part, with both parts welded together.

[Problem that the invention seeks to solve]

In the conventional rear arm described in the above-mentioned publication, the body portion is constructed of an integrally cast product, which is advantageous in terms of improved rigidity, but the mold shape is complicated and productivity is slightly inferior. Furthermore, in general, welding of cast products and extruded or drawn materials requires additional work steps such as pretreatment such as preheating, and there is still room for improvement in terms of welding workability.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a rear arm for a motorcycle that can ensure sufficient rigidity and also improve productivity and weldability.

[Means for solving problems]

The present invention provides a rear arm for a motorcycle, in which a cross member part that connects at least the left and right arm parts of the body part and supports the rear wheel suspension is made of a lightweight material that is extruded or pultruded in the vehicle width direction. The left side is made of an alloy member and is inevitably generated during the molding process of the body part.
The opening at the right end is covered by the left and right arms, and both are fixed by welding.

Here, the body part in the present invention is disposed so as to cover the cross member part, the upper and lower surfaces of the cross member part, the left and right arm parts, and the pivot part, and is inserted through the shock absorber of the rear wheel suspension system. The cross member part and the reinforcing part may be formed integrally or separately, and by the extrusion or pultrusion, at least It is only necessary to form the cross member portion, and of course, the entire body portion may be integrally formed. Furthermore, the body portion and the pivot portion may be integrally formed by the extrusion or pultrusion molding. .

In the present invention, supporting the rear wheel suspension by the cross member means, for example, rotatably supporting one end of the link member that supports the lower end of the shock absorber.

Further, the arm portion in the present invention may be formed by extrusion or pultrusion, or may be formed by sheet metal processing.

[Effect]

According to the rear arm of a motorcycle according to the present invention, at least the cross member portion of the body portion is made of a light alloy member formed by extrusion molding or pultrusion molding in the vehicle width direction.
The fiber direction of the cross member portion is arranged in the vehicle width direction. Therefore, a large load from the rear wheel acts in a direction that bends these fibers, and as a result, the resistance to the bending force of the rear arm increases, and the overall rigidity can be improved.

In addition, in the case of such extruded and drawn materials, openings inevitably occur at the left and right ends, but in the present invention, these openings are closed by the left and right arm sections, so unnecessary members are eliminated. It is not necessary and the structure can be simplified accordingly.

Furthermore, when using extrusion processing or drawing processing, mass production is easier than when using the conventional casting described above, and this is advantageous in terms of productivity. Furthermore, in welding the cross member part made of extruded material of the present invention and the arm part made of extruded material, processed sheet metal material, etc., weldability is better than in the case of welding with conventional cast products. Productivity can also be improved from this point of view.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 6 are diagrams for explaining a rear arm of a motorcycle according to a first embodiment of the present invention.

In the figure, reference numeral 1 denotes a motorcycle in which the rear arm of this embodiment is adopted, and its body frame 2 has a steering shaft cylinder 2b at the front end of a pair of left and right main frames 2a, and a bracket 2C at the rear end. The bracket 2 is fixed by welding, respectively.
The lower end of C and the front lower surface of the main frame 2a are removably connected by a pair of left and right down chapes 2d.

A front fork 3 is pivotally supported on the steering shaft cylinder 2b so as to be rotatable left and right, a front end 4 is pivotally supported on the lower end of the front fork 3, and a steering handle 5 is fixed to the upper end. There is. Further, a fuel tank 6 and a seat 7 are mounted on the upper part of the vehicle body frame 2, and an engine (not shown) is mounted on the lower part, and the front part of the vehicle is surrounded by a cowling 2e.

The rear arm 8 of this embodiment is pivotally supported on the bracket 2c of the vehicle body frame 2 so as to be able to swing up and down.
A rear wheel 9 is pivotally supported at the rear end of the rear arm 8. This rear arm 8 is composed of a pair of left and right arm sections 10, a body section 11 connecting the front ends of both arm sections 1o, and a pivot tube 12 fixed to the front end of the body section 11.

Each of the arm portions 10 includes a pair of outer member 10a and inner member 10 formed from aluminum alloy plates into a U-shaped cross section.
b are joined together with their respective openings facing each other, and the overlapped portions of both are welded and fixed. When viewed from the side, the left and right arm portions 10 have the largest vertical height near the link support portion of the rear wheel suspension system, which will be described later.
From this part, it gradually becomes smaller in both the front and rear directions.

In addition, at the rear end of each arm 10, there is an axle support plate.
10c is fixed by welding. An axle 9a of the rear wheel 9 is installed between the left and right support brackets 10c.

The body part 11 is formed by extruding aluminum alloy so that its fiber direction is in the vehicle width direction, and consists of a cross member 14 and a pair of reinforcements extending from the upper and lower edges toward the front of the vehicle body. The portions 15a and 15b are integrally formed.

The Talos member section 14 includes a top wall section 11a and a bottom wall section 11.
b, It is formed into a cylindrical shape consisting of a rear wall portion 11c and a reinforcing wall lid, and the left and right ends are open. Further, a support bracket lle is integrally formed on the lower surface of the bottom wall portion 11b, and a rear wheel suspension device 13 is attached to the bracket lie.
One end of the link 13a is pivotally supported. The link 13
The other end of a is pivotally supported near the lower end of the bracket 2c of the vehicle body frame 2, and a shock absorber 13 is located in the middle of the link 13a.
The lower end of b is pivotally supported. Further, the reinforcement portions 15a, 1
5b is formed with a through hole 11f through which the shock absorber 13b of the rear wheel suspension system 13 is inserted, and a reinforcing wall lid is integrally formed between the front portions of both.

The left and right openings of the body portion 11 are the left and right openings.
It is covered by the front end portion 10d of the outer member 10a of the right arm portion 10. The front end 10e of the inner member 10b is in contact with the rear wall 11c of the body 11, and the front ends 10d, 10e and the body 11 are fixed by welding.

The pivot tube 12 is a round pipe made of aluminum alloy, and has the reinforcing portion 15a.

Both plates 15a are disposed between the front ends of the plates 15b.

15b and the outer member 10a of the arm portion 10 by welding.

Next, the effects of this embodiment will be explained.

In the motorcycle 1 as in this embodiment, a large load from the rear wheel 9 is borne by the body frame 2 via the rear arm 8. In this case, the left and right arm portions 10 of the rear arm 2
In this embodiment, a large bending force is applied in the vehicle width direction to the body part 11 that connects the body part 1.
1 is made up of extruded members in the vehicle width direction, the bending force acts in the direction of bending the fibers produced by extrusion molding, and as a result, the resistance force against bending of the body part 11 increases, resulting in The rigidity of the rear arm 8 can be improved. Furthermore, this extruded material is easier to mass produce than conventional cast products, and productivity can be improved.

In addition, when the body part 11 is constructed of extruded members in the vehicle width direction, openings are formed at both ends, but in this embodiment, these openings are formed at the front ends 10 of the left and right arm parts
Since the opening is covered by d, a separate member is not required to close the opening, and the structure is simplified.

Further, since the opening is closed by the arm portion 10, the body portion 11 becomes box-shaped, and the rigidity can be improved from this point as well.

Moreover, since the support bracket lie that supports the link 13a of the rear wheel suspension system 13 is also molded at the same time as the extrusion molding, the structure becomes simpler. Furthermore, regarding the left and right arm sections 10, the maximum bending moment acts near the support bracket ie, but in this embodiment, since the arm section 10 is made of a sheet metal type, this maximum bending moment By increasing the height in the vertical direction of the part where the bending force acts, the section modulus of this part can be adjusted to a size corresponding to the bending moment, and a mechanically rational shape can be manufactured at low cost.

In the above embodiment, the left and right arm portions 10 were formed by sheet metal processing, but as shown in FIG. 7, the left and right arm portions 20 may be formed by extrusion molding or pultrusion molding. good.

In this way, fewer welding locations are required than when the arm portion is formed by sheet metal processing, and manufacturing costs can be reduced accordingly.

Further, in the above embodiment, the body portion 11 and the pivot tube 12
However, as shown in FIG. 8, the body portion 21a and the pivot portion 21b may be formed integrally by extrusion molding or pultrusion molding in the vehicle width direction. This will further reduce the number of welding points and further reduce costs.

Next, a second embodiment of the present invention will be described.

9 to 11 are for explaining the second embodiment, and in the figures, the same reference numerals as in FIGS. 1 to 5 indicate the same or corresponding parts.

This example is an example in which only the cross member portion 14 of the body portion 11 is extruded from aluminum alloy,
A diagonal rib 14b is integrally formed inside the cross member portion 14. As shown in FIG. The substantially central portion of the top wall portion 11a of the cross member portion 14 and the reinforcing wall lid
A step-shaped positioning part 14a is formed in the vehicle width direction at the lower end edge, and the rear end edges of sheet metal mold reinforcing parts 15a, 15b are welded and fixed to the positioning part 14a. A section 11 is configured. In addition, the reinforcement part 1
A pivot tube 12 is welded and fixed between the front ends of 5a and 15b.

Also, the top wall portion 11a of the cross member portion 14.

The front end portion 10a of the inner member 10b of the arm portion 1o is fitted so as to sandwich the bottom wall portion 11b.
The upper and lower surfaces of the reinforcing parts 15a, 15b and the inner member 10b are located on the same plane as shown in FIG. 11(a). Further, left and right arm portions 1 are arranged so as to sandwich the front end loe of the inner member lob and the left and right end surfaces of the reinforcing portions 15a and 15b, and to cover the left and right openings of the body portion 11.
0 outer members 10a are arranged, and these body parts 11. Pivot tube 12. The left and right arm portions 10 are welded and fixed to each other.

According to this embodiment, since the cross member portion 14 is constructed of an extruded member in the vehicle width direction, the rigidity can be improved, productivity can be improved, and substantially the same effects as in the first embodiment can be obtained.

Further, in this embodiment, the cross member portion 14 is connected to the inner member 1.
Since it was sandwiched between the front end toe of 0b and fixed by welding,
The rigidity of the joint can be improved accordingly. Furthermore, since the reinforcing portions 15a, 15b and the upper and lower surfaces of the inner member 10b are located on the same plane, there is no need to bend the contact surface of the outer member 10a, and welding becomes reliable.
From this point as well, the joint rigidity can be improved.

〔Effect of the invention〕

As described above, according to the rear arm of a motorcycle according to the present invention, at least the cross member portion of the body portion is made of extruded material or drawn material in the vehicle width direction, and the left side of this
The right opening is covered by the left and right arms, and both are fixed by welding, which improves the rigidity of the rear arm and improves productivity. The structure can be simplified by not requiring separate members.

[Brief explanation of the drawing]

1 to 6 are diagrams for explaining a rear arm of a motorcycle according to a first embodiment of the present invention, and FIG.
2 and 3 are a plan view, a side view, and a front view of the rear arm, respectively, FIG. 4 is a cross-sectional side view of the body, FIG. 5 is an exploded perspective view of the rear arm, and FIG. 6 is a rear arm of the embodiment. A side view of the adopted motorcycle, FIGS. 7 and 8 are exploded perspective views showing modifications of the above embodiment, respectively, and FIGS. 9 to 11 are diagrams for explaining a second embodiment of the present invention. FIG. 9 and FIG. 1O are respectively a perspective view and an exploded perspective view of the rear arm, FIG.
Figure 1 (al cross-sectional side view taken along line XI b - XI b. In the figure, 1 is a motorcycle, 2 is a body frame, 8 is a rear arm, 9 is a rear wheel, 10 is a left and right arm part, 10d
11 is a front end of the arm portion, 11 is a body portion, 12 is a pivot tube (pivot portion), 13 is a rear wheel suspension device, and 14 is a cross member portion. Patent Applicant Yamaha Motor Co., Ltd. Agent Patent Attorney Tsutomu Figure 5 Figure 7 Figure 8 n Figure 9 Figure 11 (a)

Claims (1)

[Claims] (1) In a rear arm of a motorcycle in which the front ends of a pair of left and right arm parts that pivotally support the rear wheel are connected by a body part, and a pivot part that is pivotally supported on the body frame is formed at the front end of the body part. , at least a cross member portion of the body portion that connects the arm portion and supports the rear wheel suspension is formed by extruding or drawing a light alloy material in the vehicle width direction; A rear arm for a motorcycle, characterized in that the left and right openings are covered by the front end portions of the left and right arm portions, and the arm portions and the body portion are fixed by welding.