JPS643753Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a front fork, and more particularly to a front fork with an improved fixing structure to a hollow pipe of a stopper that locks the upper end of a rebound shock spring. The upper end of the rebound shock spring installed in the front fork is held under the neck of the hollow pipe that stands up in the inner tube, but in recent years,
In order to reduce the weight of the front fork itself, lightweight materials such as aluminum and hard synthetic resin are sometimes used as the material for the hollow pipe. In this case, as shown in FIG. 2B, a stopper 41 is attached to the lower neck portion 36 of the hollow pipe 30 to increase the contact area between the lower neck portion of the hollow pipe and the upper end of the expansion side buffer spring. It is necessary to distribute the load and improve durability. Therefore, when fixing the stopper to the lower neck portion of the hollow pipe, the stopper is sometimes caulked 44, but this caulking may actually weaken the durability of the lower neck portion of the hollow pipe. There is a risk that the lower neck portion of the hollow pipe may break due to repeated impacts that cannot be controlled even by the extension side buffer spring. Therefore, the object of the present invention is to provide a front fork in which the upper end of the rebound side buffer spring is locked to a stopper fixed by a caulking structure that does not cause unexpected breakage in the lower part of the neck of the hollow pipe. To achieve this purpose, its structure is as follows.
The upper end of the hollow pipe slides into the inner tube, which is inserted into the inner tube from the upper end of the outer tube, and the middle part of the hollow pipe has a smaller diameter than the upper end of the hollow pipe and extends downward. A piston is fixed to the lower end of the tube, and a piston is provided inside the tip of the inner tube to slide on the outer circumferential surface of the intermediate portion of the hollow pipe, and an expansion side buffer spring is interposed between the upper surface of the piston and the lower surface of the upper end of the hollow pipe. In the front fork, a narrow caulking groove is formed along the axial direction of the hollow pipe, and the depth gradually increases downward on the outer periphery of the lower neck part of the hollow pipe, and the stopper is inserted into the lower neck part of the hollow pipe. is fixed in the caulking groove by caulking, and furthermore, the upper end of the expansion side buffer spring is engaged with the stopper. Hereinafter, the present invention will be explained based on the illustrated embodiments. As shown in FIG. 1, the front fork according to the present invention includes an outer tube 10, an inner tube 20 inserted into the outer tube 10, a hollow pipe 30 inserted into the inner tube 20, and a hollow pipe 30 inserted into the inner tube 20. It has an extension side buffer spring 40 interposed between the hollow pipe 30 and the inner tube 20. The outer tube 10 has a sealing member 11 at its upper end and has the inner tube 20 inside.
is slidably inserted. A bracket 12 is provided on the outer periphery slightly above the lower end.
This makes it possible to install the front fork. The inner tube 20 has a piston 21 inside its tip, and the piston 21 forms an upper chamber A in the inner tube 20 and a lower chamber B in the outer tube 10. An oil passage 22 is bored in the piston 21, and a check valve 23 is attached to the piston 21 so as to be openable and closable.
is closed, and the check valve 23 is pushed up during the compression operation, allowing a portion of the oil in the lower chamber B to flow into the opposing upper chamber A. The pipe 30 includes the inner tube 20
The upper end portion 31, which is a large diameter piston, is inserted into the piston in sliding contact with the intermediate portion 32, which has a smaller diameter than the upper end portion 31, and allows the piston 21 to come into sliding contact with the outer peripheral surface of the intermediate portion 32. , and the lower end is fixed inside the lower end of the outer tube 10. An upper orifice 33 is bored near the upper end of the intermediate portion 32 of this hollow pipe 30, and a lower orifice 34 is bored near the lower end. The chamber A and the liquid chamber C are communicated with each other by an upper orifice 33, and the lower chamber B and the liquid chamber C are communicated with each other by a lower orifice 34.
Note that a ring member 35 serving as a seal is fitted to the upper end 31 of the hollow pipe 30, and the upper end 31 is fitted with a ring member 35 serving as a seal.
Care is taken to prevent oil from leaking from the upper chamber A into the inner tube 20, that is, into the liquid chamber C, through the sliding contact between the inner tube 1 and the inner tube 20.
Additionally, an inner tube 20 is provided above the liquid chamber C.
A gas chamber C' is provided to compensate for the intrusion volume. Therefore, during the pressure stroke in which the piston 21, that is, the inner tube 20 descends, most of the oil in the lower chamber B flows into the liquid chamber C through the lower orifice 34 bored in the hollow pipe 30, and at the same time, the oil in the upper chamber B flows into the liquid chamber C. Oil from the liquid chamber C flows into the interior through the orifice 33 above. Furthermore, during the extension stroke in which the inner tube 20 rises, most of the oil in the upper chamber A flows into the liquid chamber C through the upper orifice 33, and at the same time, the oil in the lower chamber B flows through the lower orifice 34 into the liquid chamber C. This will cause oil to flow in. The upper and lower orifices 33, 3
4, a desired rebound or compression damping force is generated. The expansion side buffer spring 40 has its upper end locked by a stopper 41 inserted into and fixed to the outer periphery of the lower neck portion 36 which is a continuous portion between the upper end 31 and the intermediate portion 32 of the hollow pipe 30. and the hollow pipe 30, and when the inner tube 20 moves greatly to its maximum extension, the lower surface of the upper end 31 of the hollow pipe 30 and the upper surface of the piston 21 collide with each other with a large impact. It is placed in order to prevent this from happening. This stopper 41 is fixed to the lower neck portion 36 of the hollow pipe 30, as shown in FIG. A caulking groove 44 is formed on the outer periphery of the cylindrical portion 42 along the axial direction of the hollow pipe 30.
have. The caulking groove 44 is formed so that its depth gradually increases toward the bottom of the hollow pipe 30. In order to ensure this condition, in this embodiment, the groove 44 is formed on the exit side, that is, as shown in the figure. The lower part is sheared. In addition, since the exit side is sheared, the end thereof rises rapidly, and the stopper 41 is prevented from falling off toward the bottom of the hollow pipe 30. When forming the caulking groove 44 as a method of fixing the stopper 41 to the lower neck portion 36 of the hollow pipe 30, as shown in FIG.
A narrow caulking groove 44 is formed in the circumferential direction of the

[Table] As a result, sufficient holding force cannot be obtained with the structure of the caulking groove 44 shown in FIG. It has been found that the durability of the lower neck portion 36 of 30 is further reduced. Therefore, when the hollow pipe 30 is made of a lightweight material such as aluminum or hard synthetic resin, a stopper 4 is provided at the lower neck portion 36 of the hollow pipe 30.
1, a caulking groove 44 that is narrow and gradually deepens along the axial direction of the hollow pipe 30.
If the hollow pipe 3 is to be formed,
The inner tube 2 is made so large that it cannot be controlled by the repulsive force of the extension side buffer spring 40 that is locked to the stopper 41, without creating a thin part that would reduce the durability of the lower neck part 36 of the inner tube 2.
0 moves and a large impact due to the collision acts on the lower neck portion 36 of the hollow pipe 30, the load is distributed and there is no possibility of the lower neck portion 36 breaking. In addition, the extension side buffer spring 4 which is stopped by the stopper 41
The upper end of 0 is connected to the cylindrical portion 42 of the stopper 41.
It is fitted into the flange 43 and abuts against the flange 43. Further, a suspension spring 24 is disposed inside the inner tube 20, and its upper end is locked inside the upper end of the inner tube 20, and its lower end is locked to the upper end of the upper end 31 of the hollow pipe 30. The lowered inner tube 20 is urged to rise by its repulsive force. As described above, according to the front fork of the present invention, the stopper fixed to the outer periphery of the lower neck portion of the hollow pipe is located in the caulking groove that is formed along the axial direction of the hollow pipe and gradually deepens. Since it is caulked and fixed, the durability of the lower neck portion of the hollow pipe can be improved and the stopper can be prevented from falling off. Furthermore, even if the hollow pipe is made of lightweight material such as aluminum or hard synthetic resin, the stopper can be fixed to the lower part of the neck via the caulking groove with a small caulking load. This has the advantage of eliminating the risk of reducing the durability of the lower neck area. As a result, even if the repeated load caused by the rise of the inner tube which is so large that it cannot be controlled by the extension side buffer spring is applied to the lower part of the neck, there is a risk of the lower part of the neck breaking. This has the effect of improving the durability of motorcycles that use this front fork.

[Brief explanation of the drawing]

Figure 1 is a partially cutaway front view of the front fork according to the present invention, and Figure 2A is a partially cutaway and enlarged view of the stopper fixed to the lower neck of the pipe. Figure 2B is a partially cutaway front view of a conventional front fork. DESCRIPTION OF SYMBOLS 10... Outer tube, 20... Inner tube, 21... Piston, 30... Hollow pipe, 31... Upper end part, 32... Middle part, 36...
Lower neck portion, 40... extension side buffer spring, 41... stopper, 44... caulking groove.

Claims (1)

[Scope of utility model registration request] The upper end of the hollow pipe is slid into contact with the inner tube, which is inserted into and out of the upper end of the outer tube, and the middle part of the hollow pipe has a smaller diameter than the upper end of the hollow pipe and extends downward. A piston is fixed to the lower end of the tube, and a piston is provided inside the tip of the inner tube to slide on the outer circumferential surface of the intermediate portion of the hollow pipe, and an expansion side buffer spring is interposed between the upper surface of the piston and the lower surface of the upper end of the hollow pipe. In this front fork, a narrow caulking groove that gradually increases in depth downward is formed on the outer periphery of the lower part of the neck of the hollow pipe along the axial direction of the hollow pipe, and the stopper inserted into the lower part of the neck of the hollow pipe is A front fork is caulked and fixed in the caulking groove, and further has an upper end of an extension side buffer spring locked to the stopper.