JPS6234878A - Frame for 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 frame for a motorcycle, and particularly to improving the joint strength between a head pipe and a main pipe thereof.

[Conventional technology]

There have been various types of motorcycle frames, for example:
A head pipe that pivots the front fork is fixed to the front end of the left and right pair of main pipes, and a rear arm bracket that pivots the rear arm is fixed to the rear end of the pair.Furthermore, this bracket and the front part of the main pipe are connected by a down tube. There is a so-called double cradle type frame that is connected. In order to reduce the weight and increase the rigidity of a frame having such a shape, the applicant has proposed that the main pipe be constructed of a vertically elongated square pipe with a rectangular cross section, and has already filed an application. (Special application 1982-
156868).

[Problem that the invention seeks to solve]

By the way, in a frame for a two-wheeled motor vehicle, due to its structure, the weight of the body, occupants, etc. acts on the joint between the head pipe and the main pipe as a large bending moment.

Therefore, there has been a demand for improving the rigidity of this joint, for example, in the frame related to the above-mentioned earlier application,
In order to improve joint strength, the front end of the main pipe is formed to have approximately the same length in the vertical direction as the head pipe.

The present invention has been made in view of the conventional situation, and it is an object of the present invention to provide a frame for a motorcycle that can further improve the joint strength between the main pipe and the head pipe compared to the frame of the prior application.

[Means for solving problems]

Therefore, in the frame of a motorcycle, the present invention integrally forms a connecting seat at the center of the head pipe in the vehicle width direction, which has approximately the same height as the side wall height of the main pipe and projects a predetermined length toward the rear of the vehicle body. It is characterized in that the inner walls of the left and right main pipes are welded to the left and right end surfaces of the connecting seat, thereby integrally connecting the left and right main pipes via the head pipe and the connecting seat. Here, the protruding dimension of the connecting seat is selected to be larger as the required bonding strength is greater.

[Effect]

In the present invention having the above configuration, the joint between the head pipe and the main pipe is such that the inner walls of the left and right main pipes are connected to each other via a connecting seat, that is, this connecting seat is a cross that connects both main pipes. In addition to acting as a member, since this joint has a box-shaped structure, the strength of this joint is much improved compared to simply welding the front end of the main pipe against the head pipe.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 show one embodiment of the present invention.

In the figure, reference numeral 2 denotes a frame of a motorcycle 1, which is of a so-called double cradle type.

This frame 2 has the front ends of a pair of left and right main pipes 4.4 fixed to the head pipe 3, and a rear arm bracket 5 fixed to the rear end of each main pipe 4. and the lower front surface of the lower part are connected by a down tube 6.

A front fork 8 that supports a front wheel 7 is pivotally supported on the head pipe 3. Also above left.

There are seat rails 9 on the right main pipes 4 and 4, respectively.
The front end of each seat rail 9 is fixed, and a bang stay l is provided between the rear part of each seat rail 9 and each rear arm bracket 5.
O is fixed in place. Furthermore, each of the above seat rails 9
A side member 11 is arranged and fixed between the front part of the rear arm bracket 5 and the outside of the backstay lO of the rear arm bracket 5. A seat 12 is mounted on the seat rail 9, and a fuel tank 13a, an air cleaner 13b, and a cover 13G covering these are mounted on the main pipe 4.

Further, a rear wheel 14 is located in the middle of the rear arm bracket 5.
A rear arm 15 supporting the main pipe 4. An engine 16 is mounted in a space formed by the rear arm bracket 5 and the down tube 6, and the front lower part of the engine 16 is fixed to the down tube 6, and the rear upper part 16a is fixed to the rear arm bracket 5.

As shown in Fig. 1, the left and right main pipes 4.4 have their front portions expanded outward in the vehicle width direction around the head pipe 3, and their central portions are approximately parallel to each other. It is bent, and the rear part extends straight. Each main pipe 4 has an inner wall 4a and an outer wall 4b formed by bending an aluminum alloy plate into a U-shaped cross section.
The opening of the inner wall 4a is inserted into the opening of the outer wall 4b, and the overlapping portions of the two are welded. In other words, this main pipe 4 has a vertically long rectangular shape when viewed in cross section, and its front end is the head pipe 3.
The height is approximately the same as that of the vehicle, but the height at the rear of the vehicle is lower.

The head pipe 3 is a cylindrical body made of aluminum alloy casting, and has a support hole 3a formed at its lower end to support the steering shaft of the front fork 8 via a bearing. On the outer surface of the side wall of the hend pipe 3, a connecting seat 3b for welding and fixing the front end of each of the main pipes 4 is integrally formed to protrude. This connecting seat 3b
consists of an inner pressure 3C and an outer seat 3d, diagonally rearward,
That is, when viewed from the connecting direction of the main pipe 4, it has approximately the same shape as the joint end of the main pipe 4, that is, it has a vertically elongated rectangular shape.

The inner pressure 3C extends axially from the center of the head pipe 3 in the vehicle width direction and has a T-shaped cross section projecting toward the rear of the vehicle body, and the outer seat 3d is located above the inner pressure 3C.
It has a U-shape extending outward from the lower end with a gap 3e. The outer surfaces of the inner walls 4a of the left and right main pipes 4 are welded to both ends of the lateral sides of the inner pressure 3C, and the outer walls 4b of the main pipes 4 are fixed to the outer seats 3d.
The inner surface is welded and fixed. In other words, the inner pressure 3C of the connecting seat 3b functions as a cross member that joins the main pipes 4 immediately after the head pipe 3. In this way above left.

The right main pipe 4.4 is integrally fixedly connected to the connecting seat 3b and the side wall of the head pipe 3, and the joints between the head pipe 3 and the left and right main pipes 4, 4 are box-shaped. It has a type structure.

As described above, in the frame 2 of this embodiment, the connecting seat 3b is formed on the head pipe 3 so that the inner pressure 3c of the connecting seat 3b protrudes largely toward the rear of the vehicle body, and the inner wall of the left and right main pipes 4 is connected to this inner pressure 3c. 4a is welded, this inner pressure 3C acts as a cross member, and the inner walls 4a of the left and right main pipes 4 are fixed together by this inner pressure 3C, and this joint has a box-shaped structure. The joint strength is greatly improved compared to the case where the main pipe 4 is simply butted against the head pipe 3 and welded.

In addition, when welding the front end of the main pipe 4 to the head pipe 3, the front end of the main pipe 4 is fitted into the connecting seat 3b and positioned by simply pressing it from the outside in the vehicle width direction. becomes easy and reliable.

〔Effect of the invention〕

As described above, according to the motorcycle frame according to the present invention, the connecting seat is integrally formed with the hend pipe so as to protrude greatly toward the rear of the vehicle body, and the inner wall of the main pipe is welded to the connecting seat. The main pipe can be fixedly joined together through the head pipe and the connecting seat, which has the effect of improving the joint strength between the main pipe and the head pipe.

[Brief explanation of drawings]

FIG. 1 is a plan view of a frame according to an embodiment of the present invention, FIG. 2 is a sectional view showing the state of connection between the head pipe and main pipe, and FIG. 3 is a sectional view taken along the line ■-m in FIG. 1. FIG. 4 shows the hend pipe of the above embodiment, FIG. 4(a) is a half-sectional plan view thereof, FIG. 4(b) is a side view thereof, and FIG.
c) is a rear view thereof, and FIG. 5 is a side view of the motorcycle to which the above embodiment is applied. In the figure, 1 is a motorcycle, 2 is a frame, 3 is a head pipe, 3C is an inner pressure (connection seat), 4 is a main pipe, 4a is an inner wall, 5 is a rear arm bracket, 6 is a down tube, 8 is a front fork , 15 is a rear arm. Figure 1b Figure 4(a)

Claims (1)

[Claims] (1) The front ends of the pair of left and right main pipes are fixed to the steering head pipe (hereinafter referred to as head pipe) that pivotally supports the front fork, and the rear arm bracket that pivotally supports the rear arm is fixed to the rear end of the main pipe. , in a frame of a motorcycle in which the rear arm bracket and the front part of the main pipe are connected by a down tube below the main pipe, the main pipe is formed into a rectangular tube shape with a vertically elongated cross section, and The pipe is made of aluminum alloy casting, and a connecting seat is integrally formed at the center of the head pipe in the vehicle width direction, having approximately the same height as the side wall height of the main pipe, and protruding a predetermined length toward the rear of the vehicle body. A motorcycle frame characterized in that the inner walls of the left and right main pipes are welded to the left and right end surfaces of the seat.