JPH0222509Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention particularly relates to a variable damping force type front fork having a seat pipe having a double cylindrical structure.

A variable damping force front fork is proposed, in which an inner and an outer cylinder are slidably fitted together, and a sheet pipe is installed at the inner bottom of the outer cylinder, and the inner pipe and outer pipe form a double cylindrical structure.

Incidentally, in this type of front fork, the inner pipe is fixed by press-fitting its upper and lower ends to the inner periphery of the outer pipe, and a seal ring is fitted and held in the press-fitting portion of the lower end. However, if the inner diameter of the outer pipe is the same as the diameter of the press-fitted part at the lower end of the inner pipe, when the inner pipe is assembled into the outer pipe from above, the seal ring held at the press-fitted part at the lower end of the inner pipe will absorb the oil drilled into the outer pipe. This causes problems such as interference with the periphery of the hole and cuts.

The present invention was developed in view of such problems, and its purpose is to protect the seal ring fitted and held in the lower end press-fit portion of the inner pipe, facilitate assembly work, and reduce weight. To provide a front fork with variable damping force.

In order to achieve this purpose, the present invention has an inner and an outer cylinder fitted together slidably, a sheet pipe installed at the bottom of the outer cylinder, and an inner pipe and an outer pipe forming a double cylindrical structure. A variable damping force front fork having upper and lower ends of the pipe press-fitted into the inner periphery of the outer pipe is characterized in that the inner periphery diameter of the outer pipe is larger than the press-fitted diameter of the lower end of the inner pipe.

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

FIG. 1 is a half-cut sectional view of a front fork according to the present invention, and FIG. 2 is an enlarged detailed view of the seat pipe portion of the front fork.

In the front fork 1 shown in FIG.
2 is an outer cylinder whose upper end is open, and an inner cylinder 3 is inserted and fitted into the outer cylinder 2 from above so as to be vertically slidable as shown in the figure.

On the other hand, a seat pipe 4 is provided at the bottom of the outer cylinder 2.
is installed with bolts 5, and an oil lock piece 6 is fitted around the outer periphery of the lower end of the seat pipe 4.

By the way, this seat pipe 4 has a double cylindrical structure with an inner pipe 7 and an outer pipe 8 as shown in the figure, and a gap ΔS is formed between both pipes 7 and 8, so that the upper end of the outer pipe 8 The enlarged diameter portion 8d is in sliding contact with the inner periphery of the inner cylinder 3 as shown. Oil holes 7a are formed in the side wall of the inner pipe 7, and oil holes 8a, 8b, 8c are formed in the side wall of the outer pipe 8 at a predetermined distance from above.

The inner pipe 7 is fixed within the outer pipe 8 by press-fitting the lower end enlarged diameter portions 7b, 7c into the outer pipe 8, as shown in detail in FIG. The lower end enlarged diameter portion 7c of the inner pipe 7 is press-fitted through a seal ring 9.

By the way, the inner circumferential diameter D of the outer pipe 8 excluding the lower end press-fitted portion is set larger than the outer diameter d of the lower end enlarged diameter portion 7c of the inner pipe 7, and therefore the outer pipe 8 excluding the lower end press-fitted portion The side wall of the portion is formed thin as shown in the figure.

On the other hand, the upper end of the inner cylinder 3 is connected to the fork bolt 1.
As shown in the figure, a coil spring 12 is installed between the collar 11 screwed onto the lower part of the fork bolt 10 and the upper end surface of the seat pipe 4.
is strung up. Also, on the inner periphery of the lower end of this inner cylinder 3 is a free valve 1 that slides into contact with the outer periphery of the seat pipe 4.
3 and the oil lock piece 6 during the maximum compression stroke.
An oil lock collar 14 to be fitted is fitted.

Further, an oil seal 15 and a lock guide 16 are fitted on the inner periphery of the upper end of the outer cylinder 2 and are fitted in sliding contact with the outer periphery of the inner cylinder 3, and a dust seal 17 is further provided on the upper end of the outer cylinder 2.

The inside of the front fork 1 is divided into seat pipe inner/outer chambers S ₁ , S ₂ , intermediate chamber S ₃ and upper chamber S ₄ , and inside each chamber S ₁ , S ₂ , S ₃ , S ₄ Hydraulic oil is sealed, and the upper part of the upper chamber _S4 is occupied by gas.

In the above, since the inner circumferential diameter D of the outer pipe 8 was set larger than the outer diameter d of the lower end enlarged diameter part 7c of the inner pipe 7 (D>d), the inner pipe 7 was inserted from above the outer pipe 8. When the upper and lower end enlarged diameter parts 7b, 7c are press-fitted, the seal ring 9 fitted around the outer periphery of the lower end enlarged diameter part 7c opens the oil holes 8a..., 8b... formed in the side wall of the outer pipe 8.
The seal ring 9 is effectively protected from the risk of being cut due to contact with the seal ring 9.

Furthermore, since the inner pipe 7 is easily inserted into the outer pipe 8, the work of assembling the inner pipe 7 into the outer pipe 8 is facilitated.

Furthermore, since the side wall of the outer pipe 8 is made thinner, the weight of the front fork 1 can also be reduced.

As is clear from the above description, according to the present invention, in a front fork in which a seat pipe is constructed by press-fitting an inner pipe into an outer pipe, the inner circumferential diameter of the outer pipe is set to be smaller than the press-fitting diameter of the lower end of the inner pipe. Due to the large diameter, it is possible to retain the seal ring fitted and held in the lower end press-fit portion of the inner pipe, facilitate the work of assembling the inner pipe, and reduce the weight of the front fork.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a half-mounted sectional view of a front fork according to the present invention, and FIG. 2 is an enlarged detailed view of the seat pipe portion of the front fork. In the drawing, 1 is a variable damping force front fork, 2 is an outer cylinder, 3 is an inner cylinder, 4 is a seat pipe, and 7 is a front fork with variable damping force.
8 is an inner pipe, 8 is an outer pipe, and 9 is a seal ring.

Claims (1)

[Scope of utility model registration request] The inner and outer cylinders are slidably fitted together, and a sheet pipe is planted in the inner bottom of the outer cylinder, and the inner pipe and outer pipe form a double cylindrical structure, with the upper end of the inner pipe and the lower end fitted with a sealing member. A variable damping force front fork press-fitted into the inner circumference of an outer pipe, characterized in that the inner circumferential diameter of the outer pipe is larger than the diameter of the lower end press-fitted into the inner pipe.