JPS59227579A - Shock absorber for rear wheel of motorcycle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a rear wheel suspension system for a motorcycle that can provide an effective auxiliary equipment storage space within a vehicle body frame, as well as achieve a lower center of gravity and progressive characteristics.

The front end of the swing arm, which supports the rear wheel at the rear end, is pivotally connected to the rear of the vehicle body frame so that it can swing up and down, and the swing arm and the shock absorber are connected so that they can rotate through a link and a bell crank. In motorcycles with a so-called progressive characteristic that compresses the shock absorber while gradually increasing the load associated with swinging of the arm, the layout of a single shock absorber is such that it runs vertically through the center of the body frame and is either upright or slightly forward. Because it is tilted or placed along the main frame, it tends to interfere with other auxiliary equipment, such as carburetors, air cleaners, batteries, exhaust pipes, etc., making the installation layout difficult and maintenance difficult. - It is also inconvenient.

Further, the layout of the shock absorber as described above is undesirable because the center of gravity of the vehicle becomes high, resulting in poor steering stability and instability during cornering.

Therefore, the present invention creates a spacious space within the body frame by arranging one shock absorber approximately horizontally in the front-rear direction under the body frame near the center of gravity, and achieves progressive characteristics through a link mechanism. It is an object of the present invention to provide a rear wheel suspension system for a motorcycle having a simple structure.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a side view showing the basic structure of a motorcycle incorporating a device according to the present invention, in which a body frame 1 includes a down frame 3 extending downward and rearward from a head pipe 2, and a fuel tank 4.
It consists of a main frame 5 that supports the main frame 5, a rear upper frame 6 and a rear lower frame 7 that extend further rearward, and these are formed, for example, from an aluminum alloy square section hollow extrusion. It is welded and fixed to a pair of integrally molded left and right center frames 8.

One side of the rear fork 9 is pivoted to the front of the center frame 8 by a pivot shaft 10 so as to be freely movable downward, and a rear wheel 11 is pivotally supported at the rear end.

A shock absorber 12 that absorbs and buffers the load caused by upward movement of the rear wheel 11 is an O-ar frame 13 connected to the down frame 3.
As shown in FIG. 2, the cross member 1 is disposed in a substantially horizontal vertical position in the longitudinal direction below the engine unit 14, and its front end is installed across the left and right lower frames 13, respectively.
It is pivoted to the bracket 16 of No. 5 via a support shaft 17.

By installing the shock absorber 12, which is a heavy object, under the vehicle body frame, the center of gravity can be lowered.
The moment of inertia of the surroundings is reduced, and steering stability is improved.

When a gas pressurized type damper is adopted as the damper of the shock absorber 12, the reservoir tank 18 is placed horizontally at the bottom of the down frame 3 as shown in the figure, connected to the oil passage 20, and facing the opening 20 of the under cowl 19. If the damping force is placed in the same position, the cooling effect of the hydraulic oil is excellent and stable damping force can be obtained.

An end of a lower arm 23a of a bell crank 23 is pivotally attached to the lower protrusion 21 of the center frame 8 together with a support shaft 22, and the bent portion of the bell crank is connected to the buffer via a pivot 24. The rear pivot of the vessel 12 is pivotally connected.

The -1-arm 2'3b extending rearward from the bent portion is divided into left and right U-shapes, and is disposed at the lower part of the left and right arm forks 9, respectively, and has a support shaft at the end of the lower arm 23b. The upper end of the link 9 is pivotally connected to the inner side surface of the rear fork 9 via a support shaft 26 via a support shaft 25 .

In this way, at the rear of the shock absorber 12, the end of the lower arm 23a of the bell crank 23 is rotatably supported on the center frame 8 forming the vehicle body frame, so that the lower movement of the lower arm 23b and the rear fork 9 is damped. Since this is converted into a reciprocating movement in the back and forth direction (horizontal direction) that expands and contracts the container 12, efficient load transmission can be achieved.

In the side view of FIG. 1, the support shaft 17 is taken as point a, and the pivot
4 is the point b, and the support shaft 22 is the 0 point (a, b).

By setting C to an acute angle when no load is applied, when the bell crank 23 rotates due to the upward movement of the rear fork 9, (a,
As b and c approach a right angle, the amount of compression of the shock absorber 12 can be increased in an accelerated manner, thereby increasing the elastic force during full flexion and preventing bottoming.

Therefore, in the small swing range of the rear fork, the elastic force of the shock absorber is soft, and a strong load acts on the rear fork.
A hard elastic force is obtained in the maximum swing range, and this relationship is shown in FIG.

Next, the operation will be explained.

As shown in FIGS. 1 and 3, when a load is applied to the rear wheel 11 in the direction of arrow F, the rear fork 9 moves from the pivot shaft 1.
The link 27 rotates counterclockwise around 0, thereby also moving the link 27 in the "Y" direction.

Therefore, the bell crank 23 connected to the link 27
is rotated around the support shaft 22 in the same direction as the rear fork 9, and the pivot 24 is rotated forward (to the left in the figure) in the direction of arrow F2.
Move the buffer 12 in an arcuate path as shown in the arrow F.
3, it is compressed in a substantially horizontal direction to absorb and attenuate the impact load.

When the load decreases, the bell crank 23 is pushed back by the elastic force of the shock absorber 12, and rotates clockwise around the support shaft 22, so the link 27 indexes the rear fork 9 downward, for example, 1G. The situation will be restored.

Figure 4 shows the buffer 1 placed along the down frame 3.
The lower end of 2 and the negative side of a rotatable bell crank 4° are pivotally connected to each other by a support shaft 43, and the other side of this bell crank 40 and the support shaft 4
1 to the bell crank 23 on the rear fork 9 side.
The rear wheel is connected to the pivot shaft 24 by a connecting rod 42 to transmit the rear wheel load, and each arrow indicates the direction in which the load applied to the rear wheel is applied.

In this way, in the embodiment shown in FIG. 4, the shock absorber 12 is compressed by the connecting rod 42 running vertically under the vehicle body frame, so that the engine unit can be compressed as described in Japanese Patent Publication No. 56-131474. Since there are no load transmission rods interposed between the front and side parts, the external design is favorable and the transmission efficiency is also favorable.

As is clear from the explanation below, according to the present invention, one shock absorber is disposed at the bottom of the vehicle body frame in the longitudinal direction, and the downward movement of the rear fork is directed to the bell crank in a substantially horizontal direction via a link. Since the structure is configured so that the shock absorber is compressed by swinging the rear fork, there is no shock absorber on the pivot shaft of the rear fork, and a wide effective space can be secured within the vehicle body frame. , air cleaner, battery, etc., and is particularly effective in the layout of a plurality of exhaust pipes in a two-stroke multi-cylinder engine. In addition, desired progressive characteristics can be easily set, and
It requires fewer components, makes it possible to lower the center of gravity of the vehicle as much as possible, and thereby improves steering stability, making it ideal as a rear wheel suspension system for motorcycles. . Of course, this can also be applied to three-wheeled buggies with one front wheel and two rear wheels.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a side view of a motorcycle to which the rear wheel suspension system of the present invention is applied, and FIG.
3 is a perspective view showing the operation of the main parts of FIG. 1 and the load transmission direction, FIG. 4 is a side view of the motorcycle showing another embodiment, and FIG. FIG. 4 is a front view, and FIG. 6 is a graph showing the buffer characteristics. In addition, in the drawing, 1 is the body frame, 3 is the down frame, 8 is the center frame, 11
12 is a rear wheel, 12 is a shock absorber, 15 is a cross member, 23 is a bell crank, and 27 is a link. Patent applicant Yoshi 1) Akira Teru

Claims (2)

[Claims] (1) The front end of the rear fork, which supports the rear wheel at its rear end, is pivoted to the rear of the vehicle so that it can swing upwards, and a member for transmitting the load caused by the vertical movement of the rear wheel is pivoted to the rear fork. , a rear wheel suspension system for a motorcycle comprising one end supported in the front-rear direction at the bottom of the vehicle body frame and connected to the other end of a shock absorber disposed approximately horizontally, in which one end of the link is pivotally suspended below the rear fork. , and connects the other end of the link to the upper arm end of the bell crank via a support shaft, pivotally connecting the other end of the shock absorber to the bent portion l of the bell crank, and connecting the lower arm end extending downward. It is characterized in that it is pivotally connected to a projecting part of the center frame so as to be able to swing freely, and the load applied to the rear wheel is transmitted to the shock absorber via the link and the bell crank, and the load is absorbed by the shock absorber. Rear wheel suspension system for motorcycles. (2) One end of a rear wheel shock absorber arranged along the down frame is pivotally supported on the down frame extending downward from the head pipe of the vehicle body frame, and the lower end of the shock absorber and one end of the bell crank are supported. In the rear wheel suspension system, both ends of a suspension rod, which is disposed approximately horizontally in the front-rear direction at the bottom of the vehicle body frame, are swingably connected to the other end of the bell crank and the bent portion of the bell crank on the rear fork side. A rear wheel suspension system for a motorcycle, characterized in that the rear wheel suspension system for a motorcycle is configured to be pivotally supported on the rear wheel, transmit the load applied to the rear wheel to the shock absorber via the connecting rod, and absorb the shock.