JPS6234879A - 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] [Industrial Application Field] The present invention relates to a frame for a motorcycle, and in particular, to facilitate positioning of a head pipe and a main pipe during welding;
This also relates to improving the bonding strength.

[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 general, in a frame for a motorcycle, due to its structure, the weight of the body, occupants, etc. acts as a large bending moment at the joint between the head pipe and the main pipe.

Therefore, it has been conventionally required to improve the rigidity of this joint in frames for motorcycles. In order to improve this joint strength, it is necessary to easily and reliably position the head pipe and the main pipe during welding.

The present invention has been made in view of the conventional situation, and an object of the present invention is to provide a frame for a motorcycle in which positioning of a main pipe and a hend pipe during welding is easy and reliable, and the joint strength can be improved. There is.

[Means for solving problems]

Therefore, in the frame of a motorcycle, the present invention includes a head pipe having a shape that is substantially the same as the joint end of the main pipe.
In other words, a vertically elongated rectangular connecting seat is provided, and the main pipe and the connecting seat are connected so that the outer surface of the inner wall of the main pipe and the inner surface of the outer wall of the main pipe contact the inner surface of the inner seat and the outer surface of the outer seat of the connecting seat, respectively. The feature is that they are fitted together and then welded and fixed together in this state.

[Effect]

In the present invention having the above structure, when welding the main pipe and the head pipe, the joining end of the main pipe is fitted into the connecting seat of the head pipe, and in this state, the joint end is pressed from the outside. The main pipe and head pipe are positioned. Therefore, positioning is easier and more reliable than in the conventional case where the main pipe is simply butted against the head pipe. Further, in this case, the main pipe and the connecting seat overlap each other by a predetermined length, making it easy to fillet weld the two, and as a result, the joint strength is improved.

〔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, 2 is a frame of the motorcycle 1, which is a so-called double cradle type frame. 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 vibe 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 hend pipe 3. Also above left.

There are seat rails 9 on the right main pipe 4 and 4 respectively.
The front end of each seat rail 9 is fixed, and a back stay 1 is provided between the rear part of each seat rail 9 and each rear arm bracket 5.
0 is fixed in position. 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 10. A seat 12 is mounted on the seat rail 9, and a fuel tank 13a, an air cleaner 13b, and a cover 13c 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 bent so as to be approximately parallel to each other. The rear part extends in a straight line. 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 previous model, 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. A connecting seat 3b for welding and fixing the front end of each of the main pipes 4 is integrally formed on the outer surface of the side wall of the head pipe 3 to protrude. This connecting seat 3b
consists of an inner seat 3c and an outer seat 3d, diagonally rearward,
That is, when viewed from the connection direction of the main pipe 4, it has substantially the same shape as the joint end of the main pipe 4, that is, it has a vertically elongated rectangular shape.

The inner seat 3C extends axially from the center of the hedopipe 30 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 seat 3C.
- It has a U-shape extending outward with a gap 3e from the lower end, and the gap 3e between the outer seat 3d and the inner seat 3C prevents interference between the two when fitting the connecting seat 3b and the main pipe 4. It is an escape to avoid.

Here, the procedure for welding and joining the head pipe 3 and main pipe 4 will be explained.

First, the front end joint portion of the main pipe 4 is inserted and fitted into the connecting seat 3b. That is, the main pipe 4 is connected to the connecting seat 3 so that the inner wall 4a and the outer wall 4b of the main pipe 4 are respectively located inside the inner seat 3c of the connecting seat 3b and outside the outer seat 3d.
Fit with b. If the main pipe 4 is pressed inward in the vehicle width direction in this state, the main pipe 4 and the head pipe 3 are positioned so as to overlap by a predetermined dimension in the longitudinal direction of the vehicle body. Next, in this state, main pipe 4
By fillet welding the connecting seat 3b and the connecting seat 3b, the welding connection between the two is completed.

As described above, in the frame 2 of this embodiment, the head pipe 3 has a connecting seat 3 which has substantially the same shape as the joint end of the main pipe 4.
b is formed, positioning can be performed simply by fitting the two and pressing from the outside, and positioning can be performed more easily and reliably than in the conventional method in which the main pipe is butted against the head pipe for positioning. In addition, in this case, since the two parts are positioned so that they are overlapped by a predetermined dimension, fillet welding can be easily performed, resulting in a stronger joint than the conventional welding where the main pipe is simply butted against the head pipe. will improve.

In the above embodiment, in order to enable the connection seat 3b and the main pipe 4 to fit together, a relief, that is, a gap 3e, is provided in the connection seat 3b, but this relief is conversely provided at the joint end of the main pipe 4. It may be formed into

〔Effect of the invention〕

As described above, according to the frame of the motorcycle according to the present invention, the connecting seat having substantially the same shape as the joint end of the main pipe is formed on the head pipe, and the two are fitted together.
This has the effect that positioning during welding can be performed easily and reliably, and as a result, the joint strength can be improved.

[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 head 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, l is a motorcycle, 2 is a frame, 3 is a head pipe, 3b is a connecting seat, 3c is an inside seat, 3d is an outside seat, 4 is a main pipe, 4a is an inside wall, 4b is an outside wall, 5
is a rear arm bracket, 6 is a down tube, 8 is a front fork, and 15 is a rear arm.

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 cast aluminum alloy, and the head pipe is provided with a protruding connecting seat having approximately the same shape as the joint end of the main pipe, and the outer surface of the inner wall of the main pipe and the inner surface of the outer wall are respectively connected to the connecting seat. A frame for a motorcycle, characterized in that a main pipe and a connecting seat are fitted together so as to come into contact with the inner surface of an inner seat and the outer surface of an outer seat, and the two are fixed by welding.