JPH0115588Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a rear swing arm for a motorcycle that reduces the number of parts and costs.

In a motorcycle, a suspension unit is installed approximately in the center of the vehicle body frame, the lower end of which is attached near the front end of the rear swing arm, and the upper end is connected to the rear swing arm via an arm called a bell crank and a suspension rod. There is one that is connected approximately to the center of the arm. FIG. 1 is for explaining the load values applied to each part of the rear swing arm in this type of motorcycle.

In this figure, 1 is the rear swing arm, 2 is the front end that becomes the pivot center to the vehicle body frame (not shown), and 3 is the rear end that becomes the support part (axle center) of the rear axle (not shown). . A bracket 4 is attached to a position near the front end of the rear swing arm 1 facing downward.
A suspension unit 7 is attached by shafts 8 and 9 to the front end of a bell crank 6 whose central portion is supported by a shaft 5 on the vehicle body frame. A suspension rod 11 is attached by shafts 12 and 13 between the rear end of the bell crank 6 and a bracket 10 provided approximately at the center of the rear swing arm 1.

The loads applied to each part of the rear swing arm 1 with such a configuration are as shown in the upper part of Fig. 1.
This will be shown by the BMD curve. As is clear from this figure, the bending moment due to the load applied to the rear swing arm 1 is zero at the front end 2 and rear end 3, and is maximum at the shaft 10. For this reason, it is necessary to reinforce the rear swing arm 1 at the portion where the bending moment is maximum (the front and rear portions of the joint pipe 14, which will be described later).

Therefore, as shown in FIG. 2, two left and right arm pipes 15, 15 forming the rear swing arm 1
It has been considered to attach reinforcements 16, 16 by welding to the front and back of the joint pipe 14 that connects the joint pipes, but this structure requires a large number of parts and is related to this. There was a problem that the welding length became long and the cost increased.

The present invention has been made to solve this problem. Therefore, in the present invention, two joint pipes bent in an arc shape are joined together with their protruding sides either not facing each other or partially overlapping to obtain a combined joint pipe, and this combined body is made such that the front end is It is pivoted to the vehicle body frame and connected between two arm pipes that support the rear axle at the rear end.

Hereinafter, one embodiment of the present invention will be explained with reference to FIG. 3. The rear swing arm 1 of this embodiment is as follows:
Two joint pipes 14, 14 bent into an arc shape
, with their protruding sides placed back to back to obtain a combined body of joint pipes, and this combined body is connected to two arm pipes 15, 15 whose front ends are pivotally connected to the vehicle body frame and whose rear ends support the rear axle. It is connected to the part where the bending moment is large. Thereby, the front and rear portions of the arm pipe 15 can be reinforced. What is shown in FIG. 4 is an embodiment of the present invention, which is a modification of the one shown in FIG. In this case, the two joint pipes 14 are not placed back to back, but are partially polymerized to obtain a combined body. It is desirable that this overlapping portion be flattened by being crushed by an external force.

By configuring the present invention as described above, it is possible to obtain a rear swing arm having sufficient strength with a simple structure including a small number of parts.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the load values applied to each part of the rear swing arm, Fig. 2 is a plan view of the rear swing arm in the process leading up to the present invention, Fig. 3 is a plan view of an embodiment of the present invention, FIG. 4 is a plan view of another embodiment of the present invention. 1... Rear swing arm, 2... Front end, 3...
...Rear end, 14...Joint pipe, 15...Arm pipe.

Claims (1)

[Scope of utility model registration request] Two joint pipes bent into an arc shape are joined together with their protruding sides not facing each other or partially polymerized to obtain a joint pipe joint, and the joint pipe is made of
A rear swing arm for a motorcycle, characterized in that a front end is pivotally connected to a vehicle body frame, and a rear end is connected between two arm pipes that support a rear axle.