JPS5953288A - Front fork for two-wheel barrow - 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 (A) Field of Industrial Application The present invention relates to a front fork for a two-wheeled vehicle, and particularly to a front fork made of carbon fiber reinforced plastic (hereinafter referred to as CFRP) (1).

(B) Prior art The front fork of a two-wheeled vehicle consists of a fork pipe and a bottom case that is slidably fitted to the fork pipe, and conventionally, both of these have been made of steel.

On the other hand, CFRI', which is made by curing and molding carbon fiber with thermosetting resin such as epoxy resin or polyester resin, has CI characteristics such as high strength and elastic modulus, good vibration reduction properties, and is lightweight. This material is attracting attention as a structural member. For this reason, practical application has been progressing in the aircraft sector, where weight reduction has traditionally been a particular focus.
At present, it has not yet been put to practical use in vehicles, especially passenger cars.

However, in recent years, there has been an increasing need to reduce the weight of passenger cars from the perspective of energy conservation.
Application of FRP is being considered.

(c) Problems to be solved by the invention Conventional front forks for two-wheeled vehicles are made of steel, so machining and surface treatment are easy (2). It has the disadvantage of being.

Furthermore, when CF RP is subjected to mechanical processing such as thread cutting or grooving, the carbon fibers may curl or peel off.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a front fork made of CFRP that has rigidity and strength equivalent to or greater than steel front forks, can be easily machined, and is lightweight.

In order to solve the problem and achieve the purpose of the invention,
In this invention, both the fork pipe and the bottom case constituting the front fork are made of CFRP, and a metal layer is provided on the inner surface of these.

(e) Embodiment FIG. 1 shows a front fork in which a fork pipe 1 is coaxially fitted to a bottom case 2. The fork pipe 1 is fixed to the front part of the vehicle body, and the bottom case 2 is fixed to the axle of the front wheel. Inside the front fork, a vehicle suspension spring 3, a piston 4, etc. are housed, and buffer oil is sealed.

The above-mentioned fork pipe 1 and bottom case 2 each have a metal layer 6 provided on the inner surface of pipes 5, 5 made of CFRP. C forming pipes 5, 5 (see Figure 2)
Since the fiber orientation of FRP can be arbitrarily selected, CFRP pipes with a high longitudinal elastic modulus (axial elastic modulus)5,
5 has a fiber orientation close to the machine direction, e.g. 00 to 2.
This is possible by increasing the number of winding angles of 0°. C
FRI) pipe 5.5 has a longitudinal elastic modulus of 10.000
K2shio is made of steel (longitudinal elastic modulus 21,000
In order to obtain the same bending rigidity as Kfi'/+i), the wall thickness should be increased by about 2.1 times, and in this case, the weight can be reduced by about 50%.

Further, the metal layer 6 may include aluminum, aluminum alloy,
It is formed by inserting and gluing a light metal pipe made of magnesium alloy, titanium, etc. into the entire inner surface or both end portions of the pipes 5, 5, which require machining. in this case,
Since the thermal expansion coefficients of the CFRP pipes 5, 5 and the metal layer 6 are different, the CF
When RP is wrapped and hardened, there is a risk of peeling due to the difference in thermal expansion. Therefore, CFRP pipe 5,
5 and the metal pipe are manufactured separately and then bonded together, or the metal pipe is manufactured with an outer diameter slightly larger than the inner diameter of the CFRP pipes 5, 5, and after applying adhesive, the press-fit adhesive method is used, in which both are press-fitted. It is desirable to integrate the Note that the finishing accuracy of the outer surface may be improved by providing a thin metal layer on all or part of the outer surface of the fork pipe 1 by plating or the like.

(f) Experimental results By winding carbon fiber impregnated with epoxy resin so that the ratio of 10° helical winding to 90° winding (circumferential winding) was 8:2 and hardening it, the inner diameter was 33 mm.
Outer diameter 41+mn, longitudinal elastic modulus 12,000K 9/
I made rrd CFRP pipe. On the other hand, the inner diameter is 29mm, and the outer diameter is 0.0311v from the inner diameter of the above CFRP pipe.
An aluminum alloy pipe machined to a large size was manufactured, and the outer surface was subjected to surface treatment to strengthen the adhesive force with the CFRP pipe. Next, an epoxy adhesive was applied to the inner surface of the CFRP pipe and the outer surface of the aluminum alloy, and both were press-fitted and bonded using a press device. After press-fitting and gluing, machining is performed, and the inner diameter is 29mm, the outer diameter is 41mm, and the length is 6001run.
Manufactured an FRP fork pipe. This fork pipe was approximately 40% lighter in weight than a steel fork pipe with an outer diameter of 41 mm having the same bending rigidity, and was also high in strength.

(G) Effects As described above, this invention uses CFRP for the front fork.
By making the front fork made of steel, it has a rigidity and strength equal to or greater than that of a steel front fork.

It is possible to provide a front fork that is significantly lighter than one made of steel. It is also suitable for mass production because it can be made in large numbers from a long pipe.

Furthermore, by providing a metal layer on the inner surface, machining can be performed without causing the CFRP to turn over or peel, and the same effect as that made of steel can be exhibited.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the front fork, and Fig. 2 is a partially enlarged sectional view thereof. 1...Fork pipe> 2...Bottom case, 5,
5... CFRI' pipe, 6... Metal layer. Patent applicant: Honda Motor Co., Ltd. Sumitomo Electric Industries, Ltd. Agent
Sickle 1) Sentence 2 rings 1 figure - in 1 - 2 figures

Claims (1)

[Claims] (1) In a front fork for a motorcycle consisting of a fork pipe and a bottom case fitted concentrically with the fork pipe, the fork pipe and bottom case described in - are made of carbon fiber reinforced plastic pipes, A front fork for a two-wheeled vehicle characterized by having a metal layer on all or part of the inner surface. +2+ -! - formed by a metal pipe with a metal layer;
A front fork for a two-wheeled vehicle according to claim 1, wherein the metal pipe is adhesively bonded or press-fit adhesively bonded to the inner surface of a carbon fiber reinforced plastic pipe.