JPS5929468B2 - Motorcycle rear wheel shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rear wheel shock absorber for a progressive type motorcycle, which is capable of increasing the amount of increase in the buffering force of a shock absorber more than the amount of rocking of a rear wheel support frame that supports the rear wheel.

In motocross and off-road motorcycles that travel on rough terrain, a swingable rear wheel support frame such as a rear fork has a larger amount of vertical swing than in general motorcycles.

In addition, in this type of off-road motorcycle, the buffering force characteristic of the rear wheel shock absorber is not proportional to the upward swinging displacement of the rear wheel support frame, and the increase in the buffer force of the shock absorber is determined by the rear wheel support frame. A progressive type shock absorber is used, which is capable of increasing the amount of rocking.

In this type of shock absorber, the lower end of the shock absorber, whose upper end is connected to the vehicle body frame, is connected to a rotating member pivotally connected to the rear wheel support frame, and the vehicle body frame and this rotating member are connected via a rod member. , The rotating member rotates due to the axial load generated on the rod member due to the swinging of the rear wheel support frame, which increases the amount of compression of the shock absorber and generates a large shock absorbing force, which increases with the curved line. This is done to obtain buffering force characteristics.

According to this, it is possible to effectively absorb the shock load transmitted from the road surface to the vehicle body via the rear wheels, and the riding comfort is improved.
By the way, off-road motorcycles are required to have good maneuverability and stability, and in order to achieve this, it is advantageous to reduce the moment of inertia around the center of gravity of the vehicle, and the shock absorber is relatively large. Because of the weight, even in motorcycles in which a progressive mechanism is configured with the above-mentioned rotating member and rod member, and the shock absorber is retracted and moved by this mechanism, the placement and connection points of the shock absorber should be considered.
It is desirable to reduce the moment of inertia. Also, when the shock absorber is compressed and deformed by upward swinging of the rear wheel support frame at a rate of increase greater than the amount of rocking, the large reaction force due to this shrinkage deformation is Since it acts on the rear wheel support frame, it is desirable to consider the position of the point of application of this reaction force so as to be advantageous in terms of the strength of the rear wheel support frame.

The inventors of the present invention have developed the present invention in view of the above-mentioned demands and to meet these demands.

An object of the present invention is to arrange a rotating member to be located forward of the center portion of the rear wheel support frame in the longitudinal direction, and to
The lower end of a shock absorber whose upper end is pivotally connected to the vehicle body frame is connected to the front part of the upper part of the rotating member in the longitudinal direction of the vehicle body, so that the lower end of the shock absorber is connected as much as possible to the center of gravity of the vehicle that exists around the engine in front of the rear wheel support frame. The maneuverability and stability of the motorcycle can be improved by bringing the shock absorber closer to the vehicle and reducing the moment of inertia around the center of gravity of the vehicle. Provided is a rear wheel shock absorber for a motorcycle, which uses a progressive rock structure consisting of a rotating member and a rod member to ensure a large compression stroke of the shock absorber, thereby achieving the shock absorbing effect required for off-road motorcycles, etc. There is a place to do it.

Another object of the present invention is to connect the lower part of the rotating member and the vehicle body frame side through a rod member, and to connect the upper part of the rotating member at the rear in the longitudinal direction of the vehicle body to the rear wheel support frame. Therefore, even if the rotating member is disposed forward of the longitudinal center of the rear wheel support frame, the point of action where the reaction force due to the shrinkage deformation of the shock absorber acts on the rear wheel supporting frame via this rotating member is reduced. An object of the present invention is to provide a rear wheel shock absorbing device for a motorcycle which can be moved rearward, reduces the load on a rear wheel support frame, and is advantageous in terms of strength.

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 main parts of an off-road motorcycle to which the device according to the present invention is applied, FIG. 2 is a bottom view of FIG. 1, and FIG. 3 is an exploded view.

The engine 1 is mounted and fixed on the bottom part 2a of the vehicle body frame 2, and the rear end of the bottom part 2a is bent approximately vertically to stand up.
b, and a bracket 4 provided with a hole 4a as shown in FIG. 3 is welded to this raised portion 2b.

The rear part of the engine 1 is connected and supported by a bracket member 5 to the upright part 2b of the vehicle body frame 2, and this bracket member 5 is a partially modified version of the conventional one. It consists of side plates 5a, 5b, and a cylindrical member 5c that traverses and connects these 5a, 5b. Holes 6 and 7 are provided at the top and bottom of each of the side plates 5a and 5b with the cylindrical portion 5c in between, and these holes 6 and 7 are aligned with the holes 1a and 1b provided at the rear of the engine 1, so that a bracket is installed at the rear of the engine. The bracket member 5 is attached to the rear part of the engine 1 by fitting the member 5 and inserting and screwing the bolts 8 and 9 into the holes 6, 1a and 7, 1b. In this embodiment, the rear wheel support frame, ie, the rear fork, on which the rear wheel 3 is pivoted at its rear end, is of a monocoque type.

A pair of protrusions 10a, 10 are provided at the tip of the rear fork 10.
As shown in FIG. 2, a recess 11 is provided to form a recess 11, and while inserting the bracket member 5 into the recess 11 as shown in FIG. The pivot shaft opening 3 is inserted into the hole 4a1 of the bracket 4 of the upright portion 2b, the hole 12 formed in the projections 10a and 10b of the rear fork 10, and the cylindrical portion 5c of the bracket member 5. As a result, the rear part of the engine 1 is coupled and supported to the vehicle body frame 2 by the bracket member 5, and
The front end of the rear fork 10 is pivotally connected to the vehicle body frame 2 about a pivot shaft 13 so as to be able to swing up and down.
A rotating member 14 is disposed on the rear fork 10 at a position forward of the central portion of the rear fork 10 in the longitudinal direction of the vehicle body, and this rotating member 14 is connected to an upper intermediate portion 14c in the longitudinal direction of the vehicle body as shown in FIG. It has a triangular side surface including a rear part 14a1 and a front part 14b, and in this embodiment, the front part 14b projects further forward than the upper middle part 14c and extends downward. The rear part 14a is bifurcated as shown in FIG.
A hole 15 is formed in each branch part, and by aligning the hole 15 with a pair of receiving parts 16, 16 protruding from the upper surface of the rear fork 10, and inserting and screwing bolts 17, 17, the rotating member 14 is rotated. It is pivotally connected to the rear fork 10 at the rear part 14a so as to be vertically rotatable. The lower end of a shock absorber 18 configured as a spilling damper is pivotally connected to the intermediate portion 14c of the rotating member 14 with a bolt 19, and the shock absorber 18 is extendable and retractable. It is pivotally attached to the upper part of the frame 2 so as to be swingable back and forth, and one shock absorber 18 is installed between the vehicle body frame 2 and a rotating member 14 attached to the rear fork 10. Rotating member 14
A front part 14b extending diagonally downward and forward is projected from the lower surface of the rear fork 10 through a hole 20 formed vertically through the rear fork 10, and the rear end of a rod member 21 is pivotally connected to this projecting end with a bolt 22. As shown in FIG. 3, the rod member 21 has threaded rod ends 21a on both ends of the rod body 21c.
21b] - It is constructed by connecting the rod ends 21a and 21b, and when the rod body 21c is rotated with respect to the rod ends 21a and 21b, the rod ends 21a and 21b move forward and backward to adjust the length. Side plate 5 of the bracket member 5 that connects the rear part of the engine to the vehicle body frame 2
a and 5b are extended downward, and this extension partially changes the shape of the conventional bracket member, and extending portions 23 and 24 are integrally formed at the lower part of the hole 7 position.

Cylindrical portions 23a and 24a facing each other with a gap are provided on the inner surfaces of the lower ends of the extension portions 23 and 24, and the front rod end 21b of the rod member 21 is inserted into the gap to form the cylindrical portion 23a.
, 24a, the front end of the rod member 21 is pivotally connected to the lower end of the bracket member 5, which is a side member of the vehicle body frame 2. As described above, the front part 14b of the rotating member 14 is connected to the rod member 21 on the vehicle body frame 2 side.
The front end of the rod member 21 is connected to the vehicle body frame 2 by using a bracket member 5, which is originally prepared as a part of a motorcycle to connect and support the engine 1 to the vehicle body frame 2, and whose shape has been partially changed. Concatenated.

Next, we will discuss the effect. When the motorcycle is running, the rear wheel 3 moves up and down due to the unevenness of the road surface, and the rear fork 10 moves from the chain line position in FIG. 1 to the solid line position at the pivot shaft opening 3.
Suppose that it is oscillated upward using as a fulcrum.

As the rear fork 10 swings, the rotating member 14 also rises, but the rear part 14a is attached to the rear fork 10 by the bolt 17.
A rod member 21 is connected to the front part 14b of the rotating member 14, which is pivotally attached to the front part 14b, and the rod member 21 swings in an arcuate trajectory centered on the bolt 25, so that it rotates when the rear fork 10 swings. The member 14 rotates clockwise around the bolt 17 in FIG. Therefore, the upper intermediate portion 1 of the rotating member 14
The shock absorber 18 whose lower end is connected to the rear fork 10 is compressed and deformed by the amount of rotation of the rotating member 14 added to the amount of rotation of the rear fork 10, and as a result, the buffering force of the shock absorber 18 is It increases at a larger rate than the dynamic displacement, and can increase the buffering force increase rate more than the amount of rocking of the rear fork 10. FIG. 4 is a graph showing an increase in the slowing force F with respect to the swing angle θ of the rear fork 10. As the swing angle θ increases, the buffer force F increases in a quadratic curve.

In the above, when the rotating member 14 rotates clockwise, an axial load is generated on the rod member 21, and due to the generation of this load, the rotating member 14 rotates, causing the shock absorber 18 to contract and move. Therefore, the axial load is extremely large. However, the bracket member 5 that connects and supports the front end of the rod member 21 is formed into a gate shape consisting of side plates 5a, 5b1 and a cylindrical portion 5c, and has sufficiently high rigidity and strength. This makes it possible to effectively support the axial load generated in the process, resulting in improved strength. Further, as described above, the rotating member 14 is located forward of the central portion of the rear fork 10 in the longitudinal direction of the vehicle body, and
Since the lower end of the buffer 18 is connected to the buffer 1
8 approaches the center of gravity G of the vehicle around engine 1,
By placing the relatively heavy shock absorber 18 on the front side of the rear fork 10, the moment of inertia around the center of gravity G of the motorcycle is reduced, improving the maneuverability and stability of the motorcycle. do.

Furthermore, even when the shock absorber 18 approaches the pivot shaft 13 which is the swinging fulcrum of the rear fork 10, due to the progressive rock structure consisting of the rotating member 14 and the rod member 21, the shock absorber 18 is smaller than the amount of swing of the rear fork 10. The compression stroke can be increased, and the impulse effect required for off-road motorcycles and the like can be obtained. Furthermore, when the shock absorber 18 is greatly compressed and deformed, such as in a fully collapsed state, the large reaction force of the shock absorber 18, which acts as a buffer force against the upward movement of the rear wheel 3 and the rear wheel support frame 10, is exerted by the rotating member 14. The point of action is on the bolt 17 of the rear part 14a of the rotating member 14, so even if the shock absorber 18 is brought closer to the vehicle center of gravity G, the rear wheel support frame 10 is Since the point of reaction force application is shifted rearward from the shock absorber 18, the load on the rear wheel support frame 10 is reduced, which is advantageous in terms of the strength of the rear wheel support frame 10. The rate of increase in the buffering force of the shock absorber 18 is related to the length dimension of the rod member 21.
The buffering force increase rate, etc. can be changed by adjusting the length dimension by moving b forward or backward, but Figures 5, 6, and 7 show examples for changing the buffering force increase rate over a larger range. .

As shown in FIG. 5, FIG. 6, and FIG.
5-1, 5-1, 5-2, 5-3, 5-3, 5-1, 5-2, 5-3, 5-3, 5-1, 5-2, 5-3, 5-3, 5-1, 5-1, 5-2, 5-3, 5-3, 5-1, 5-1, 5-2, 5-2, 5-3, 5-3, 5-1, 5-1, 5-1, 5-2, 5-2, 5-3, 5-3, 5-3, 5-3, 5-3, 5-3, 5-3, 5-3, 5-3, 5-3, 5-3, 5-3, and 50% have slanted forward.

The bracket member 5 is appropriately connected to these 5-1, 5-2, 5-
3, the shock absorbing characteristics of the shock absorber 18 can be changed, and by combining the exchange of the bracket member 5 and the length adjustment of the rod member 21 by moving the rod ends 21a and 21b back and forth, it is possible to change the shock absorbing characteristics of the shock absorber 18 over a wide range. You can fine-tune the buffer characteristics of the device. To replace the bracket member 5, use the bolt 8.
, 9, 13, 25 and the pivot shaft 13, and the work can be completed in a short time. 8 and 9 show another embodiment of the present invention, in which the rotating member 114 is changed.

The rotating member 114 is pivotally connected to the rear fork 110 at the upper rear part 114a, the lower end of the shock absorber 118 is connected to the upper middle part 114c, and the front part 114b is connected to the rod member 121.
The engine 101 is connected to the vehicle body frame side by a bracket member 105 for connecting the engine 101 to the vehicle body frame 102 via the bracket member 105, and unlike the previous embodiment, this front portion 114b protrudes further rearward than the front portion 114c and extends downward. The triangular side surface of the rotating member 114 with the intermediate portion 114c as its bending apex is more acute than in the previous embodiment. Further, as shown in FIG. 9, this rotating member 114 is composed of two parallel play holes 30, 130, and a spacer 132 is interposed between brackets 131a, 131a protruding from a cross member 131 of the rear fork 110. The rotating member 114 is attached to the rear fork 110 by pivotally connecting the plates 130, 130 with bolts 117. In the above example, the rear wheel support frame is rear wheel support frame. However, a swing arm that cantilever-supports the rear wheel may also be used. As is clear from the above description, according to the present invention,
Since the shock absorber can be moved closer to the center of gravity of the vehicle, the moment of inertia around the center of gravity of the motorcycle can be reduced, improving the maneuverability and stability of the motorcycle.
In addition, even though the shock absorber has been moved to the front of the vehicle body compared to conventional models, a large compression stroke of the shock absorber can be ensured by the progressive mechanism consisting of the rotating member and the rod member, and the connection between the rotating member and the rear wheel support frame is Since the connecting part is at the rear of the rotating member, the point of action of the shock absorber's shrinkage reaction force is shifted to the rear of the shock absorber, which provides advantages in terms of the strength of the rear wheel support frame. do.

[Brief explanation of drawings]

Fig. 1 is a side view of main parts of a motorcycle to which the shock absorber according to the present invention is applied, Fig. 2 is a bottom view of Fig. 1, Fig. 3 is an exploded view of the shock absorber, and Fig. 4 is a rear wheel support frame. Graphs showing the rate of increase in buffering force with respect to the swing angle of FIGS. 5, 6, and 7
The figure is a side view showing the case where the extension direction of the extension part of the engine bracket member is changed in order to change the shock absorbing characteristics. Figures 8 and 9 show another embodiment, and Figure 8 is the same as Figure 1. , and FIG. 9 are similar to FIG. 3. In the drawing, 1,101 is an engine, 2,102 is a body frame, 3 is a rear wheel, 10,110 is a rear fork that is a rear wheel support frame, 14,114 is a rotating member, 18,
118 is a shock absorber, 21 and 121 are rod members, and G is the center of gravity of the vehicle.

Claims (1)

[Claims] 1 The front end of a rear wheel support frame, which has a rear wheel mounted on the rear end thereof, is pivotally connected to the vehicle body frame so as to be able to swing vertically, and the rotating member is positioned forward of the central portion of the rear wheel support frame in the longitudinal direction of the vehicle body. At the same time, the rear part of the upper part of the rotating member in the longitudinal direction of the vehicle body is pivotally connected to the rear wheel support frame so as to be vertically rotatable, and the upper end of the upper part of the rotating member is pivotally connected to the vehicle body frame. A rear wheel shock absorber for a motorcycle, characterized in that the shock absorber is brought closer to the center of gravity of the vehicle by connecting the lower end of the shock absorber, and the lower part of the rotating member and the vehicle body frame are connected via a rod member.