JPS602071Y2 - Motorcycle rear wheel suspension system - Google Patents

Description

[Detailed description of the invention] The present invention relates to a rear wheel suspension system for a motorcycle, which effectively absorbs and absorbs the impact load applied to the rear wheel of the motorcycle, thereby increasing the cushioning effect and improving the vehicle performance. It is something.

Conventionally, a rear wheel is mounted on a shaft at the rear of a vehicle body frame, and the front end of a swinging arm of a fork or the like is pivotally supported so as to be able to swing up and down, and a cushion spring is installed between the vehicle body frame and the swinging arm.
In a two-wheeled vehicle suspension system in which a rear wheel shock absorber comprising a damper or the like is connected, the rear wheel shock absorber is connected between the body frame and the swing arm at the rear of the body frame, and the rear wheel shock absorber is connected to the rear wheel shock absorber. Since a cushion stroke of sufficient length is required to achieve the desired cushioning effect, it occupies a relatively large space behind the vehicle body frame, and there are some restrictions on the swing range of the swing arm. There are also restrictions on the placement of air cleaners, batteries, and other auxiliary equipment connected to the rear of the engine, and furthermore, the rear wheel shock absorber tends to move away from the center of gravity of the two-wheeled vehicle.

The present invention was proposed in view of the above, and is arranged approximately horizontally along the front-rear direction of the vehicle body in a rear-open dead space formed by the upper surface of the engine crankcase, the rear surface of the cylinder block, and the lower surface of the carburetor. By exposing the front end of the rear wheel shock absorber, and rotatably connecting the front end and the four rear ends of the shock absorber to the engine and the middle part of the swing arm, all of the drawbacks of the conventional shock absorber can be overcome. The purpose of the present invention is to provide a rear wheel suspension system for a motorcycle.

The first embodiment of the present invention will be described below with reference to FIG. is installed upright, and a carburetor 4 is installed on the upper rear surface of the cylinder block 3a.
A concave dead space 5 that is open to the rear is formed by the upper surface of the crankcase 3, the rear surface of the cylinder block 3a, and the lower surface of the carburetor 4.

The front end of a swinging arm 6 such as a carrier fork is pivoted 7 at the bottom of the center tube 2 of the vehicle body frame F or at the rear of the crankcase 3 so as to be able to swing up and down.
A rear wheel Wr is rotatably mounted on a shaft at the rear end, and this rear wheel Wr
is rotationally driven by the engine E via a transmission mechanism (not shown).

The swing arm 6 is formed in a triangular shape when viewed from the side,
The upper end of an arm 8 is pivotally supported 9 at the intermediate top portion thereof so as to be able to swing back and forth, and the rear end of a tension link 10 is pivotally connected 11 to the lower end of this arm 8.

The tension link 10 extends forward, and its front end is pivotally connected 12 to the lower end of the center tube 2 of the vehicle body frame F.

A rear end of a rear wheel shock absorbing device in which a rear cushion coil spring 13 and a damper 14 are arranged concentrically and overlapping each other is pivotally connected 15 to the intermediate portion of the arm 8 .

The rear wheel shock absorber extends approximately horizontally along the longitudinal direction of the vehicle body frame F, and its front end is connected to the engine E.
The front end thereof is rotatably connected 17 to a bracket 16 formed on the engine body 3.

A front fork 19 is steerably connected to a head pipe 1B at the front end of the vehicle body frame F, and a front wheel Wr is rotatably mounted on a shaft below the front fork 19.

Next, the operation of the first embodiment of the present invention will be explained. When the motorcycle is running and the rear wheel Wr is swung up and down with respect to the body frame F, the swiveling arm 6 rotates around the pivot point 7. It swings up and down, and the swing expands and contracts a shock absorber made up of a rear cushion spring 13 and a damper 14 via the arm 8, thereby buffering and absorbing the impact load transmitted to the vehicle body frame F.

In addition, the angle θ formed by the center line 1-1 passing through the center of the shaft support 9 and the pivot connection point 15 and the longitudinal axis 1'-1' of the rear wheel shock absorber during normal operation of the motorcycle is 90° or less. By setting, the following buffering characteristics can be obtained.

Now, when the swinging arm 6 swings upward, the arm 8, which is rotatably supported 9 in the middle thereof, moves upward together with the swinging arm 6. In this case, the arm 8
Since the lower end is pivotally connected 11 to the tension link 10, the pivot point 11 is gradually pulled forward as it moves upward, and in FIG. 1, the arm 8 swings while moving upward. It rotates clockwise around the pivot point 9 relative to the movable arm 6.

As a result, the amount of deflection of the shock absorber is determined by the amount of forward movement of the pivot connection point 15 along the vertical axis of the rear wheel shock absorber due to the upward swing of the swing arm 6, and the amount of forward movement of the arm 8 in the clockwise direction. This is the sum of the amount of forward movement of the pivot connection point 15 due to individual rotation, and as the amount of upward swing of the swing arm 6 increases, the forward movement rate of the pivot connection point 15 and the rotation rate of the arm 8 gradually increase. Therefore, the rate of increase in the amount of deflection of the rear wheel shock absorber increases, and if the amount of deflection δ of the rear wheel shock absorber relative to the upward movement of the rear wheel Wr is plotted on a graph, it will be as shown in Figure 3, and the rear wheel The deflection characteristics of the shock absorber are non-curved.

This means that if the amount of upward movement of the rear wheel Wr relative to the vehicle body frame F increases with an increase in the load on the vehicle body frame F or the external force acting on the rear wheel Wr, the rate of increase in the amount of deflection of the rear wheel shock absorber increases each time. As a result, the rear wheel shock absorber increases its spring rigidity, increases the amount of shock energy absorbed by the rear wheel Wr, and improves riding comfort regardless of the magnitude of the load on the vehicle body frame F. can do well.

Furthermore, by housing the front end of the rear wheel shock absorber in the dead space 5 formed in the engine E, this device can be brought closer to the center of gravity G of the motorcycle, and the weight of the motorcycle is concentrated at the center of gravity. Vehicle performance can be improved.

FIG. 4 shows a second embodiment of the invention.

In this second embodiment, the rear end of a rear wheel shock absorber whose front end is pivotally connected 17 to the engine E is directly pivotally connected 20 to the middle top of the swing arm 6 having a triangular side surface. Compared to the first embodiment, the structure of the rear wheel suspension system can be simplified.

As described above, according to the present invention, the front end of the swinging arm 6, such as a rear fork, which pivots the rear wheel Wr, is supported on the vehicle body frame F so as to be able to swing up and down, and the rear wheel Wr is In a motorcycle equipped with an engine E for driving, a cylinder block 3a is installed upright on the front upper surface of a crankcase 3, and a carburetor 4 is connected to the rear surface of the cylinder block 3a. In the rear open dead space 5 surrounded by the upper surface of the crankcase 3, the rear surface of the cylinder block 3a, and the lower surface of the carburetor 4 of E, there is a front end of a rear wheel shock absorber arranged approximately horizontally along the longitudinal direction of the vehicle body. The front end of this rear wheel shock absorber is rotatably connected to the engine E, and the rear end is rotatably connected to the intermediate portion of the swing arm 6, so that the front end of the rear wheel shock absorber By extending it into the dead space 5 of the engine E, the damping stroke of the device can be ensured to be long enough in the longitudinal direction, and its damping effect can be maximized.

Moreover, the rear wheel shock absorber itself is arranged almost horizontally, minimizing the amount of overhang above the vehicle body space.In addition, the engine E
Since the dead space 5 formed by the above can be effectively used as a storage space for the rear wheel shock absorber, a spacious vehicle body space can be formed above the rear wheel shock absorber.
The engine E's battery, air cleaner, and other auxiliary equipment can be placed relatively freely there, and the vertical swing stroke of the swing arm 6 can be secured largely, and the seat position on the body frame F can be lowered to make the motorcycle more compact. It is also possible to aim for

Furthermore, since the rear wheel shock absorber is located close to the center of gravity G of the two-wheeled vehicle, it helps to concentrate the weight of the two-wheeled vehicle near the center of gravity G, thereby improving vehicle performance.

[Brief explanation of drawings]

Figures 1 to 3 show the first embodiment of the present invention, Figure 1 is a side view thereof, Figure 2 is a view taken along the line ■-■ in Figure 1, and Figure 3 shows the amount of upward movement of the rear wheel. A graph showing the relationship between the amount of deflection of the rear wheel shock absorber and FIG. 4 is a side view of the second embodiment of the present invention. D: Rear wheel shock absorber, E: Engine, F: Body frame, Wr: Rear wheel, 3: Crank case , 3a... cylinder block, 4... carburetor, 5...
・Dead space, 6... Swinging arm, 7...
Pivot support, 15. 17.20...Concatenation.

Claims (1)

[Scope of utility model registration request] On the vehicle body frame F, the front end of a swinging arm 6 such as a rear fork that pivots on the rear wheel Wr is supported so as to be able to swing vertically, and an engine E for driving the rear wheel Wr is mounted, The engine E has a cylinder block 3a erected on the front upper surface of the crankcase 3.
In a motorcycle in which a carburetor 4 is connected to the rear surface of a,
In the rear open dead space 5 surrounded by the upper surface of the crankcase 3, the rear surface of the cylinder block 3a, and the lower surface of the carburetor 4 of the engine E, there is a rear wheel shock absorber arranged substantially horizontally along the longitudinal direction of the vehicle body. The front end of the rear wheel shock absorber is rotatably connected to the engine E, and the rear end is rotatably connected to the intermediate portion of the swing arm 6. Suspension system.