JPH0719979Y2 - Front forks for motorcycles and tricycles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a front fork of a motorcycle,
In particular, the present invention relates to a front fork that supports a front wheel via a link that is swingably supported on a fork pipe.

BACKGROUND ART In a motorcycle or the like, one end of a link is swingably supported at a lower end portion of a fork pipe provided at a lower portion of a steering stem, and an intermediate portion of the link is provided at an upper portion of the fork pipe via a cushion spring. There is known a front fork having a structure in which a front wheel is supported by the other end of the link.

Conventionally, in such a front fork, as shown in FIGS. 1 and 2, a holder 31 for swingably supporting a link is provided.
The fork pipe 32 and the fork pipe 32 are separate bodies and are fixed to each other by welding. Therefore, it is necessary to weld the pivotally supporting hole 33 of the holder 1 to the fork pipe 32 while positioning it in the longitudinal direction at the time of assembling, which is a disadvantage that the processing is very difficult.

SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned drawbacks of the conventional ones, and it is easy to position the pivot hole and improve its position accuracy, and it is very easy to machine. It is intended to provide a front fork of a tricycle.

A front fork of a motorcycle according to the present invention has a fork pipe at a lower portion of a steering stem, and a front fork of a motorcycle for supporting a front wheel through a link pivotally supported on the fork pipe. A front fork, wherein the fork pipe is a round pipe, and a lower end portion of the round pipe extends in a longitudinal direction thereof and is formed by expanding one slit provided at an opening end as desired. The concave wall surface portions surrounding at least three sides, and the wall surface portions facing each other of the concave wall surface portions have flange portions formed substantially flat so as to pivotally support the link. It has a feature.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a perspective view showing a motorcycle equipped with a front fork according to the present invention. In the figure, 1 is a handlebar, 2 is a front cover, 3 is a floor board, 4 is a body center cover, 5 is a seat, 6 is a rear cover, 7 is a transmission, 8 is a front wheel, and 9 is a rear wheel.

Steering stem 10 covered by front cover 2
In the lower part of the fork pipe 11 of a substantially inverted U shape is provided,
A link 12 is pivotally supported at one end of the lower end of the fork pipe 11 so as to be swingable. A middle portion of the link 12 is supported by the cushion spring 13 against the upper portion of the fork pipe 11, and the other end thereof supports the axle 14 of the front wheel 8.

The front fork according to the present invention is shown in FIG.
As shown in (C), the lower end portion of the fork pipe 11, that is, the pivotal support portion 15 (corresponding to the conventional holder 31) pivotably supporting the link 12 is integrally formed with the fork pipe 11. ing. The pivot portion 15 has substantially flat flange portions 16a, 16b facing each other, and each of the flange portions 16a, 16b
Pivot holes 17a and 17b are formed in this. Then, as is apparent from FIG. 4 (C), the link 12 is pivotally supported via the bush 20 by the bolt 18 and the nut 19 attached to the pivot holes 17a and 17b. O-rings 22a, 22b are interposed between the annular grooves 21a, 21b formed on the outer peripheral wall of the bush 20 and the inner peripheral wall of the link 12. 5 (A), (B) and (C) are cross-sectional views taken along line AA, BB and CC in FIG. 4 (A).

Next, a method of forming the pivot portion 15 of the fork pipe 11 will be described with reference to the process diagrams of FIGS. 6 (A) to 6 (D).

First, as shown in FIG. 6 (A), a slit 23 facing the opening end 11a is formed in the longitudinal direction of the fork pipe 11 at the tip (lower part) of the fork pipe 11. Then, as shown in FIG. 6 (B), the slit 23 is expanded and further, as shown in FIG. 6 (C), a substantially rectangular cross section having substantially flat flange portions 16a, 16b facing each other. Mold the pivot 15 of. Then, as shown in FIG. 6D, the corner portions of the flange portions 16a and 16b are rounded. The pivotal support holes 15a thus formed are provided with the aforementioned pivotal support holes 17a and 17b in the flange portions 16a and 16b. Pivot holes 17a, 17b
The peripheral edge portion of is a seat surface having high flatness.

Referring again to FIG. 3, the lower end portion of the fork pipe 11 and the link 11 are covered with a bottom link cover 24 integrally formed of plastic or the like. The bottom link cover 24 is fixed to the fork pipe 11 by screwing or the like. Thus, the fork pipe with the cover 24
By covering the lower end of 11 and the link 11, it is possible to prevent the entry of mud or the like from the bottom of the fork pipe 11, and to form a mud-preventing flange (reference numeral F in FIG. 2) at the bottom of the fork pipe as in the past. You don't have to.

In addition, in the above-described embodiment, the case where the invention is applied to the motorcycle has been described, but the present invention can also be applied to the motorcycle.

Effect of the Invention As described above, in the front fork of the motorcycle according to the present invention, since the pivot supporting portion for pivotally supporting the link is integrally formed with the fork pipe, the welding process and the number of parts required conventionally are required. And the positioning of the pivot hole becomes easy, and the positional accuracy can be greatly improved. Further, since the one slit is expanded to form the flange portion, the material formed by the pipe member can be used without waste, and thus the cost of the product can be reduced by effectively using the material.

[Brief description of drawings]

1 and 2 are perspective views showing a conventional example and a side sectional view thereof, FIG. 3 is a perspective view showing a motorcycle equipped with a front fork according to the present invention, and FIGS. 4 (A), (B) and (C) is a perspective view showing one embodiment of the present invention, its side view and its bottom view, and FIGS. 5 (A), (B) and (C).
Is the line AA, the line BB and the line C- in FIG.
A sectional view taken along the line C and FIGS. 6A to 6D are process drawings showing a method for forming the pivotal support portion of the fork pipe. Explanation of symbols for main parts 10 …… Steering stem 11 …… Fork pipe 12 …… Link 13 …… Cushion spring 15 …… Pivot support 16a, 16b …… Flange 17a, 17b …… Pivot support hole 23 …… Slit

Claims (1)

[Scope of utility model registration request] 1. A front fork of a motorcycle, comprising a fork pipe at a lower portion of a steering stem, and supporting a front wheel through a link pivotally supported on the fork pipe, the front fork of the motorcycle comprising: The fork pipe is composed of a round pipe, and a lower end portion of the round pipe extends in the longitudinal direction thereof and has a concave shape surrounding at least three sides formed by expanding one slit provided at an opening end as desired. A wall surface portion, and among the concave wall surface portions, the wall surface portions facing each other have flange portions formed substantially flat so as to pivotally support the link. Front fork.