JPH05105170A - Rear swing arm for motorcycle - Google Patents

Abstract

PURPOSE:To reduce weight and cost by reducing the number of parts of a rear swing arm and to easily carry out the assembly work for the rear swing arm, etc. CONSTITUTION:The left and right arm parts 24 and 25 are connected by a joint part 26, and at a rear swing arm 16 of a motorcycle which is supported in swingable manner on a car body frame by a pivot 27 which is formed at one edge of the left and right arm parts, the left and right arm parts are formed with different side views. Further, the joint part is formed by working a plate member 26a to a U-figure section, and these plate members 26a are joined to form a hollow structure, and the joint part is constituted so that the sectional area gradually increases in the vicinity of the left and right arm parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear swing arm of a motorcycle which is provided with left and right arm portions having different side view shapes.

[0002]

2. Description of the Related Art As shown in FIG. 7, a rear swing arm 1 of a motorcycle, which rotatably supports a rear wheel and is swingably supported by a vehicle body frame, has left and right arm portions 2 and 3. There are different shapes in side view and different cross-sectional areas. That is, the left arm portion 2 may be formed in a linear shape and thin, and the right arm portion 3 may be formed in a V shape and thick.

In such a rear swing arm 1, L
The side arm part 2 and the R side arm part 3 are connected by a joint part 4 made of casting, and the joint part 4 and the L side arm part 2 are further connected by a sub arm part 5.

[0004]

As described above, in the above-mentioned conventional rear swing arm of the motorcycle, since the sub arm portion 5 is present as the connecting member in addition to the joint portion 4, the number of parts is large and the die cost is high. The jig cost is high, and the welding length is also long, which increases the cost. Further, since the number of parts is large and the joint portion 4 is a cast product, the weight also increases.

Further, since the sub-arm portion 5 is provided, when the rear swing arm 1 is attached or detached, or when the transmission chain laid between the drive sprocket on the engine side and the driven sprocket on the rear wheel side is attached or detached. In addition, it is necessary to cut this transmission chain, which lowers the workability of assembling.

The present invention has been made in view of the above circumstances, and provides a rear swing arm for a motorcycle, in which the number of parts can be reduced to reduce the weight and cost, and the assembling work can be easily performed. The purpose is to do.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a motorcycle in which left and right arm portions are connected by a joint portion and which is swingably supported by a body frame by a pivot formed at one end of the left and right arm portions. In the rear swing arm, the left and right arm portions are formed to have different side view shapes, and the joint portion is formed by processing a plate material into a U-shaped cross section and joining these into a middle structure. The joint portion is configured such that the cross-sectional area gradually increases near the left and right arm portions.

[0008]

Therefore, according to the rear swing arm of the motorcycle of the present invention, the sub-arm portion does not intervene between the joint portion and one of the arm portions, and further, it is not necessary to provide the reinforcement portion at the joint portion. So
The number of parts can be reduced. As a result, the cost can be reduced and the weight can be reduced because the joint portion is formed of the plate material.

Further, since the sub-arm portion is not interposed between the joint portion and the arm portion, it is bridged between the rear wheel supported by the tip portion of the rear swing arm and the engine mounted on the body frame. There is no need to cut the transmission chain when attaching or detaching the transmission chain, or when attaching or detaching the rear swing arm. Therefore, the work of assembling the rear swing arm and the transmission chain can be easily performed.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of a rear swing arm of a motorcycle according to the present invention, and FIG. 2 is an overall side view of a motorcycle to which the rear swing arm of FIG. 1 is applied.

As shown in FIG. 2, in a motorcycle, an engine (not shown) is mounted at a central position of a body frame 10, and front wheels 11 and rear wheels 12 are arranged in front of and behind the engine, respectively. A front fork 13 that suspends and suspends the front wheels 11 is steerably supported by a head pipe 14 of the vehicle body frame 10, and a handle 15 is attached to an upper portion of the front fork 13.

Rear swing arm 1 for supporting the rear wheel 12
6 is pivotally supported on the body frame 10 so as to be vertically swingable. The rear swing arm 16 is buffer-suspended on the vehicle body frame 10 by the rear cushion unit 17 via the links 18 and 19. Also, the body frame 1
A seat 21 is arranged on a seat rail 20 of 0, and a fuel tank 22 is installed in front of the seat 21. Reference numeral 23 is a cowling that covers the front part of the vehicle body.

As shown in FIGS. 1, 3 and 5, the rear swing arm 16 connects the L-side arm portion 24 and the R-side arm portion 25, which are different in side view shape and cross-sectional area, by a joint portion 26. Configured.

The L-side arm portion 24 is formed in a linear shape with a square pipe. On the other hand, the R-side arm portion 25 is formed into a middle structure by joining the inner arm plate 25a and the outer arm plate 25b, which have a U-shaped cross section, so as to close the mutual opening portions. Moreover, the R-side arm portion 25 is formed in a dogleg shape whose side view projects upward.

A pivot 27 is fixed to one end of each of the L-side arm portion 24 and the R-side arm portion 25, and the rear swing arm 16 is fixed by the pivot 27.
Is swingably supported by the body frame 10. The vicinity of the pivot 27 of the L-side arm portion 24 and the R-side arm portion 25 is connected by a connecting pipe 28. Further, a rear wheel support portion 29 is provided at the other ends of the L-side arm portion 24 and the R-side arm portion 25, and the rear wheel 12 is rotatably attached to the rear wheel support portion 29 via a chain adjuster (not shown). Supported.

This chain adjuster adjusts the slack of the transmission chain 32 that is bridged between the drive sprocket 30 (see FIG. 2) installed on the engine and the driven sprocket 31 mounted on the rear wheel 12. Is.

Further, as shown in FIGS. 3 and 5, the joint portion 26 is joined so as to close the mutual opening portions of the upper plate 26a and the lower plate 26b, which are pressed into a substantially U-shaped cross section. , The middle structure. The joining position is, as shown in FIG.
It is made at the center position in the height direction of the joint portion 26. As shown in FIG. 4, the joint portion 26 includes the L-side arm portion 24 and the R-side arm portion 2 from the central portion in the longitudinal direction.
The cross-sectional area is gradually increased toward 5.

A link pipe 34 is fixed to the joint portion 26 via a bracket 33. The link 19 shown in FIG. 2 is supported by the link pipe 34, and the rear swing arm 16 is buffer-suspended by the rear cushion unit 17.

According to the above-described embodiment, the conventional sub-arm portion 5 (see FIG. 7) is not interposed between the joint portion 26 and the L-side and R-side arm portions 24 and 25, and the joint portion 26 is also provided. Since the cross-sectional area of is gradually increased toward the L-side arm portion 24 and the R-side arm portion 25, it is not necessary to provide lean reinforcement. Since it is not necessary to install a sub arm part or a lean force like this,
Since the number of parts is reduced and the welding length is shortened, the cost can be reduced.

Further, since the joint portion 26 is constituted by joining the pressed upper plate 26a and the pressed lower plate 26b, the weight can be reduced.

Further, as described above, the joint portion 26 and L
Since the sub-arm portion is not interposed between the side and R side arm portions 24 and 25, the drive sprocket 3 on the engine side
0 and the driven sprocket 31 on the side of the rear wheel 12 are attached or detached when the transmission chain 32 is attached or detached, or when the rear swing arm 16 is attached or detached.
No need to disconnect As a result, the work of assembling the rear swing arm 16 and the transmission chain 32 can be easily performed.

[0023]

As described above, according to the rear swing arm of the motorcycle of the present invention, the left and right arm portions forming the rear swing arm are formed to have different side view shapes, and the left and right arms are formed. Since the joint part that connects the parts is constructed by processing the plate material into a U-shaped cross-section and joining them to the middle structure, the cross-sectional area is gradually increased near the left and right arm parts. The number of parts of the arm can be reduced to reduce the weight and cost, and the work for assembling the rear swing arm and the like can be easily performed.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a rear swing arm of a motorcycle according to the present invention.

2 is an overall side view of a motorcycle to which the rear swing arm of FIG. 1 is applied.

FIG. 3 is a side view of the rear swing arm shown in FIG.

FIG. 4 is a plan view of the rear swing arm shown in FIG.

5 is a cross-sectional view taken along the line VV of FIG.

6 is a sectional view taken along line VI-VI of FIG.

FIG. 7 is a perspective view showing a rear swing arm of a conventional motorcycle.

8 is a perspective view showing a joint portion of FIG. 7. FIG.

[Explanation of symbols]

 10 Body Frame 12 Rear Wheel 16 Rear Swing Arm 24 L-side Arm Part 25 R-side Arm Part 26 Joint Part 26a Upper Plate 26b Lower Plate 27 Pivot

Claims (1)

[Claims] 1. A rear swing arm of a motorcycle, wherein left and right arm portions are connected by a joint portion and is pivotally supported by a body frame by a pivot formed at one end of the left and right arm portions. The arms are formed to have different side view shapes, and the joint portion is formed by processing a plate material into a U-shaped cross-section and joining these to the middle structure. A rear swing arm for a motorcycle characterized in that the cross-sectional area is gradually increased in the vicinity of the arm part of the.