JPS6220783A - Rear fork of cantilever structure 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 (Field of Industrial Application) The present invention relates to a cantilevered rear fork for a motorcycle.

(Technical background) Motorcycles use double-supported rear forks that hold the rear wheel with high rigidity, but from the standpoint of promoting weight reduction and cost reduction of vehicles, it is difficult to A fixed rear fork is preferable. However, in the case of a rear fork with a cantilevered structure, there is a problem in that it is difficult to obtain the necessary rigidity without increasing the size of the structure.

(Objective of the Invention) Therefore, in view of the above-mentioned problems, an object of the present invention is to provide a rear fork with a cantilevered structure for a motorcycle that can obtain necessary rigidity without increasing the size of the structure.

(Summary of the Invention) In order to achieve the above-mentioned object, the present invention has a longitudinal section between the base of the rear fork and the axle holding part of the rear fork. The shape is such that the pitch circle of the driven sprocket, which is arranged at

(Example) An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a racing motorcycle using a rear fork with a cantilevered structure according to the present invention, in which 1 is a body frame, 2 is
is an engine, 3 is a front wheel, 4 is a rear wheel, 5 is a handle, 6 is a fuel tank, 7 is a rear suspension, 8 is a rear fork, 9 is a drive sprocket attached to the engine 2 side (output shaft of the transmission), 10 is a driven sprocket attached to the axle 11 of the eight rear forks, and 12 is a chain that transmits rotational power from the engine 2 to the axle 11.

FIG. 2 shows the rear fork 8.
The base 8a is connected to the bracket 14 by the pivot shaft 13.
The upper end surface 8C of the rear fork 8 is pivotably supported on the frame 14 and is thus attached to the frame 14.
The chain 12 is arranged so as to run under the upper and lower end surfaces 8d.

The longitudinal section between the base 8a of the rear fork 8 and the axle holding part 8b of the rear fork 8 is tangent to the pitch circle of the drive sprocket 9 and the driven sprocket 10,
The shape gradually approaches the base portion 8a. The upper end surface 8C and lower end surface 8d portions are closest to the tangent at a substantially central portion 8e between the base portion 8a and the axle holding portion 8b. Further, the cross section of the rear fork 8 in the direction perpendicular to the longitudinal direction has a rectangular shape as a whole including the central portion 8e closest to the tangent.

The upper end surface 8C5 of the rear fork 8 has a base 8a on the lower end surface 8d.
A chain slider 15.16 made of resin or rubber located from the central part 8e closest to the tangential direction is the third chain slider 15.16.
As shown in the figure, they are fixed in a staggered manner with a plurality of screws 17 and 18. During running, the chain 12 is normally installed at a distance where the chain sliders 15 and 16 do not interfere, so they do not come into contact with each other. Also, chain 12
Even if the rear fork 8 becomes loose, the part (the central part 8e) of the rear fork 8 is close to the chain 12, so the slack will not become large and will not interfere with power transmission. The influence on the chain slider 15, 16 is also reduced, and wear on the chain slider 15, 16 is also reduced.

The rear fork 8 constructed in this way is in a normal state when it is not receiving shocks from the road surface, etc. while driving, when it is in the state shown by the solid line (substantially parallel to the road surface). The upper side of the chain 12 is the tension side, and the lower side is the slack side. Also,
In this normal state, when receiving a shock from the road surface, the rear fork 8 rotates upward about the pivot shaft as shown by an imaginary line, but in this case, the chain 12 The upper side □ is the slack side, and the lower side is the tension side. In this way, when the rear fork 8 is in the state shown by the solid line and in the state shown by the imaginary line, the tension side of the chain 12 retreats from the upper side to the lower side. It does not cause any hindrance to the running of the vehicle.

In addition, torque rods 1°9 of the rear brake are arranged on the outer surfaces of both side walls of the rear fork 8, arms 20 and 21 are respectively provided on the torque rods 19, and a torque 1J link 22 is provided on the arm 20. 21 has torque link 23
are spherically connected to each other to transmit braking force to the rear wheel 4 (shown in FIG. 1).

(Effects of the Invention) As explained above, according to the cantilever structure rear fork of the motorcycle according to the present invention, the longitudinal cross section between the base of the rear fork and the axle holding portion of the rear fork is arranged on the transmission side. gradually approaching from the base to the tangent of the pitch circle of the drive sprocket located on the axle of the rear fork and the driven sprocket located on the axle of the rear fork,
Since the shape is such that they are closest to each other at the approximate center, there is no problem in running the chain under conditions where the chain connecting the drive sprocket on the engine side and the driven sprocket on the axle side is placed on the upper end side and the lower end side. It is possible to increase the cross-sectional area of the approximately central portion in the length direction without causing any problems.

Therefore, the entire rear fork has high rigidity and can sufficiently cope with the load received from the rear wheels and the bending force acting on the axle due to braking.

In addition, the lengthwise cross section gradually approaches the tangent line between the drive sprocket and the driven sprocket from the base, and is closest in the center, so a large amount of slack in the chain is absorbed and there is no unnecessary slack in the chain. This has the advantage of eliminating the possibility of bouncing.

[Brief explanation of the drawing]

FIG. 1 is a side view of a racing motorcycle to which a cantilevered rear fork according to the present invention is applied, FIG. 2 is a side view of a cantilevered rear fork according to the present invention, and FIG. 3 is a side view of a racing motorcycle to which a cantilevered rear fork according to the invention is applied. FIG. 3 shows a plan view of such a rear fork having a cantilevered structure. 8... Rear fork, 8a... Base, 8b... Axle holding part, 8e... Center part, 9... Drive sprocket, 10... Driven sprocket, 11...
...Axle.

Claims (1)

[Claims] 1. The longitudinal section between the base of the rear fork and the axle holding part of the rear fork is aligned from the base to the tangent to the pitch circle of the drive sprocket located on the transmission side and the driven sprocket located on the axle of the rear fork. A cantilever structure rear fork for a motorcycle, characterized in that the rear fork approaches each other gradually and approaches the maximum at approximately the center.