JPH07315278A - Swing arm for motorcycle - Google Patents

Abstract

PURPOSE:To provide a swing arm, in which piping space for an engine exhaust system can be secured, for a motorcycle. CONSTITUTION:A swing arm 15 is provided with a pivot part 19, a front arm part 20F extended upward slantingly from the rear part of the pivot part 19, a rear arm part 20R extended downward from the rear end part of the front arm part 20F, and a rear wheel bearing part 21R arranged in the rear end part of the rear arm part 20R.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swing arm for a motorcycle, and more particularly to a swing arm for a motorcycle capable of ensuring a piping space for an engine exhaust system.

[0002]

2. Description of the Related Art For example, a swing arm is pivotally mounted on a pivot shaft installed in the lower center of a body frame of a motorcycle so as to be swingable around the pivot shaft. This swing arm is generally constructed by installing a cross member between the front parts of the left and right bowl parts, and providing a pivot part at the front end of this cross member, and this pivot part is pivotally attached to a pivot shaft. . Rear wheel bearings are provided at the rear ends of the left and right bowls, and the rear wheels are rotatably supported by these rear wheel bearings. Further, a rear shock absorber is attached to the swing arm on the side of the pivot portion, and a rear wheel suspension device is constituted by the swing arm and the rear shock absorber.

By the way, an engine mounted on a motorcycle is connected with an exhaust pipe constituting an engine exhaust system, and this exhaust pipe is arranged from below the engine toward, for example, the rear right side of the vehicle body. The rear part of the exhaust pipe may be led out to the outside of the swing arm.

[0004]

However, in the motorcycle having the exhaust pipe arrangement structure as described above, since the rear portion of the exhaust pipe passes below the swing arm, this portion is outside in the vehicle width direction. Moreover, it is located in a low place, which causes a narrowing of the bank angle of the motorcycle. In particular, in the case of a vehicle equipped with a two-cycle engine, since the chamber located behind the exhaust pipe has a large diameter, the minimum ground clearance is lowered accordingly, and there is a possibility that a sufficient bank angle cannot be secured depending on the layout of the chamber. is there.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a swing arm for a motorcycle capable of ensuring a piping space for an engine exhaust system.

Another object of the present invention is to have high rigidity,
The purpose is to provide a swing arm for a motorcycle having a simple structure.

[0007]

In order to solve the above-mentioned problems, a swing arm for a motorcycle according to the present invention has the following features.
As described in claim 1, the pivot portion, the front bowl portion extending obliquely rearward and upward from the rear portion of the pivot portion, and the substantially downward extending from the rear end portion of the front bowl portion. It is composed of a rear bowl portion and a rear wheel bearing portion provided at a lower end portion of the rear bowl portion.

Further, in order to solve the above-mentioned problems, as described in claim 2, the front bowl portion and the rear bowl portion are formed by pressing a plate material.

[0009]

In the present invention having the above-mentioned structure, the swing arm comprises the pivot portion, the front bowl portion extending obliquely rearward and upward from the rear portion of the pivot portion, and the rear end portion of the front bowl portion. Since it is composed of a rear bowl portion that extends substantially downward and a rear wheel bearing portion provided at the lower end portion of the rear bowl portion,
Piping space for the engine exhaust system can be secured and a sufficient bank angle can be secured.

Further, since the front bowl portion and the rear bowl portion are formed by pressing a plate material, it is possible to provide a swing arm for a motorcycle having a high rigidity and a simple structure.

[0011]

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

FIG. 1 is a right side view showing an example of a motorcycle to which the present invention is applied.

In FIG. 1, the motorcycle 1 has a vehicle body frame 2, and a fuel tank 3 is provided above the vehicle body frame 2. Further, the front portion of the vehicle body frame 2 is covered with a streamlined cowling 4 to reduce air resistance during traveling and protect the rider from traveling wind pressure. Further, the body frame 2 in the cowling 4
A two-cycle engine 5, for example, is mounted in the lower center part.

The front end of the engine 5 is connected to the front end of an exhaust pipe 6 which constitutes an engine exhaust system, and the inside of the downstream side of the exhaust pipe 6 is a chamber 7 (expansion chamber).
Has become. A silencer 8 (silencer) is connected to the rear end of the exhaust pipe 6. The exhaust pipe 6 is arranged from below the engine 5 toward the right rear of the vehicle body, for example.

A head pipe 9 is provided in front of the body frame 2.
The head pipe 9 is provided with a steering mechanism 10. The steering mechanism 10 is provided with a front fork 12 that rotatably supports the front wheels 11, a handlebar 13, and the like, and the handlebars 13 rotatably steer the front wheels 11 left and right.

On the other hand, a swing arm 15 is pivotally attached to a pivot shaft 14 which is provided at the lower center of the body frame 2 so as to swing around the pivot shaft 14, and a rear wheel 16 is rotated at the rear end of the swing arm 15. Freely supported. The lower end of the rear shock absorber 17 is attached to the upper part of the swing arm 15 on the base end side, and the upper end of the rear shock absorber 17 is attached to the vehicle body frame 2. The swing arm 15 and the rear shock absorber 17 constitute a rear wheel suspension device 18.

FIG. 2 is a right side view of the rear wheel suspension device 18, and FIG. 3 is a left side view thereof. Further, FIG. 4 is a top view of the rear wheel suspension device 18, and FIG. 5 is a rear view thereof.

For example, as shown in FIG. 2, the swing arm 15 comprises a pivot part 19, a bowl part 20, and rear wheel bearing parts 21R and 21L.

FIG. 6 is a development view of the bowl portion 20, and FIG. 7 is an assembly view of the swing arm 15.

As shown in FIGS. 2 to 7, the bowl 20 is, for example, an upper plate 22 and a lower plate 23, which are plate materials, which are press-molded in an inverted U-shape. Are formed in the middle.

From the rear part of the pivot part 19, a front bowl part 20F of the bowl part 20 extends obliquely rearward and upward, that is, above the rear wheel 16, and the rear bowl part 20 of the bowl part 20 extends from its rear end.
R extends substantially downward. And the rear bowl 20
Rear wheel bearings 21R and 21L are provided at the left and right lower ends of R, respectively.

Incidentally, although not shown in detail, the engine 5 mounted on the motorcycle 1 has an output shaft arranged on the left side in the traveling direction of the vehicle, and a drive sprocket 24 provided on the output shaft 24 The output of the engine 5 is transmitted via a chain 25 to a driven sprocket 27 that is provided on one side of the rear wheel 26 so as to rotate integrally with the rear wheel 26. On the other side of the rear wheel 26, there is a brake disc 28 for the rear brake.
Is provided integrally with the rear wheel 26 so as to rotate therewith.

As shown in FIGS. 2 and 3, the height dimension of the front bowl 20F is such that the height dimension α of the right front bowl 20F in the vehicle traveling direction is the left front bowl. Part 20
It is configured to be larger than the dimension β of F in the height direction. Further, as shown in FIGS. 4 and 6, the left front bowl 20F has a front bowl 20F so as not to interfere with the chain 25.
Is formed so as to be displaced toward the central axis of the. As shown in FIGS. 3 and 7, a reinforcing member 29 is provided between the left rear portion of the pivot portion 19 and the left rear wheel bearing portion 21L.

A rear shock absorber 17 mounting bracket 30 is fixedly attached to the rear surface of the bowl portion 20, near the pivot portion 19. A brake caliper 31 for a rear brake is provided below the right rear wheel bearing portion 21R.

Next, the operation of this embodiment will be described.

With the structure described above, the swing arm 15
The chamber 7 of the exhaust pipe 6 can be arranged behind the pivot part 19 on the right side of the without lowering the minimum ground clearance.
A sufficient bank angle can be secured.

Further, the swing arm 15 has a simple structure by press-molding the bowl portion 20 into an inverted U-shape and forming the upper plate 22 and the lower plate 23 constituting the bowl portion 20 at the center. It can be molded and high rigidity can be secured.

Further, the dimension α in the height direction of the right front bowl 20F in the traveling direction of the vehicle is defined by the left front bowl 20F.
By making it larger than the dimension β in the height direction of the above, it is sufficient as a whole even if the left front bowl portion 20F is deviated toward the central axis χ of the bowl portion 20 so as not to interfere with the chain 25. It can secure sufficient rigidity. The rigidity can be further increased by installing the reinforcing member 29 between the left rear portion of the pivot portion 19 and the left rear wheel bearing portions 21R and 21L.

[0029]

As described above, according to the swing arm of the motorcycle of the present invention, the swing arm includes the pivot part and the front bowl part extending obliquely rearward and upward from the rear part of the pivot part. And a rear bowl portion extending substantially downward from the rear end portion of the front bowl portion, and a rear wheel bearing portion provided at the lower end portion of the rear bowl portion, so that the engine exhaust system piping space Can be secured, and a sufficient bank angle can be secured.

Further, since the front bowl and the rear bowl are formed by pressing a plate material, it is possible to provide a swing arm for a motorcycle having a high rigidity and a simple structure.

[Brief description of drawings]

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

FIG. 2 is a right side view of the rear wheel suspension device.

FIG. 3 is a left side view of the rear wheel suspension device.

FIG. 4 is a top view of a rear wheel suspension device.

FIG. 5 is a rear view of the rear wheel suspension device.

FIG. 6 is a development view of a bowl portion.

FIG. 7 is an assembly drawing of a swing arm.

[Explanation of symbols]

 1 Motorcycle 2 Body Frame 5 2 Cycle Engine 6 Exhaust Pipe (Engine Exhaust System) 7 Chamber (Engine Exhaust System) 14 Pivot Shaft 15 Swing Arm 16 Rear Wheel 17 Rear Shock Absorber 18 Rear Wheel Suspension System 19 Pivot Section 20 Bowl Section 20F Front bowl 20R Rear bowl 21R, L Rear wheel bearing 29 Reinforcement member 30 Rear shock absorber mounting bracket α Right side front bowl height direction dimension β Left side front bowl height direction dimension χ Center axis of the bowl

Claims (2)

[Claims] 1. A pivot part, a front bowl part extending obliquely rearward and upward from a rear part of the pivot part, and a rear bowl part extending substantially downward from a rear end part of the front bowl part. A swing arm for a motorcycle, comprising: a rear wheel bearing portion provided at a lower end portion of the rear bowl portion. 2. The swing arm for a motorcycle according to claim 1, wherein the front bowl portion and the rear bowl portion are formed by pressing a plate material.