JPH0643197B2 - Motorcycle frame - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a motorcycle frame, and particularly to facilitating positioning of a head pipe and a main pipe during welding,
As a result, it relates to improvement of the bonding strength.

[Conventional technology]

There are various types of frames for motorcycles, for example,
A head pipe that pivotally supports the front foam is fixed to the front ends of the pair of left and right main pipes, and a rear arm bracket that pivotally supports the rear arm is fixed to the rear ends of the pair of main pipes. Further, 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 a frame having such a shape, the applicant of the present application has proposed to configure the main pipe with a rectangular pipe in cross section and a vertically long square pipe in order to achieve both weight reduction and high rigidity. (Japanese Patent Application Sho 59-
156868).

[Problems to be solved by the invention]

By the way, generally, in a motorcycle frame, the weight of a vehicle body, an occupant and the like acts on the joint between the head pipe and the main pipe as a large bending moment due to its structure.
Therefore, it has been conventionally required to improve the rigidity of this joint portion in the motorcycle frame. In order to improve the joint strength, it is necessary that the head pipe and the main pipe can be easily and reliably positioned during welding.

The present invention has been made in view of such a conventional situation, and an object thereof is to provide a frame of a motorcycle in which the positioning of the main pipe and the head pipe during welding is easy and reliable, and thus the joint strength can be improved. I am trying.

[Means for Solving Problems] Therefore, according to the present invention, in a frame of a motorcycle, the head pipe has substantially the same shape as the joint end of the main pipe,
That is, a vertically elongated rectangular connecting seat is provided 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 come into contact with the inner surface of the inner seat and the outer surface of the outer seat, respectively. It is characterized in that they are fitted together and in this state they are welded and fixed.

[Action]

In the present invention having the above-described configuration, in welding and joining the main pipe and the head pipe, the joining end portion of the main pipe is fitted to the connecting seat of the head pipe, and if pressed from the outside in this state, The main pipe and the head pipe are positioned. Therefore, the positioning becomes easier and more reliable than the conventional one in which the main pipe is simply butted against the head pipe. Further, in this case, the main pipe and the connecting seat overlap each other for a predetermined length, and the fillet welding between them becomes easy, 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 an embodiment of the present invention. In the figure, reference numeral 2 is a frame of the motorcycle 1, which is a so-called double cradle type frame. This frame 2
Is a pair of left and right main pipes 4, 4 on the head pipe 3.
The rear arm bracket 5 is fixed to the rear end of each main pipe 4, and each bracket 5 and the lower surface of the front portion of the main pipe 4 are connected by a down tube 6.

A front fork 8 supporting a front wheel 7 is pivotally supported on the head pipe 3. The front ends of the seat rails 9 are fixed on the left and right main pipes 4 and 4, and the back stays 10 are fixed between the rear portions of the seat rails 9 and the rear arm brackets 5, respectively. There is. Further, a side member 11 is arranged and fixed between the front portion of each seat rail 9 and the outside of the back stay 10 of the rear arm bracket 5. The seat 12 is placed on the seat rail 9 and the main pipe 4
A fuel tank 13a, an air cleaner 13b, and a cover 13c for covering them are attached on the top.

In the middle of the rear arm bracket 5, the rear wheel 14
A rear arm 15 for supporting the engine is pivotally supported, and an engine 16 is mounted in a space formed by the main pipe 4, the rear arm bracket 5 and the down tube 6. The upper portions 16a are fixed to the rear arm brackets 5, respectively.

As shown in FIG. 1, the left and right main pipes 4 and 4 have front portions that are widened toward the outer side in the vehicle width direction with the head pipe 3 as the center, and are bent so that the central portions are substantially parallel. Further, the rear portion extends linearly. Each of the main pipes 4 has an inner wall 4a and an outer wall 4 formed by bending an aluminum alloy plate into a U-shaped cross section.
b is prepared, the opening portion of the inner side wall 4a is inserted into the opening of the outer side wall 4b, and the overlapping portion of the both is welded to form a rectangular tube shape. That is, the main pipe 4 has a vertically long rectangular shape when viewed in cross section, and its front end portion has substantially the same height as the head pipe 3, and the height becomes lower toward the rear of the vehicle body.

The head pipe 3 is a tubular body made of cast aluminum alloy, and a support hole 3a for supporting the steering shaft of the front fork 8 via a bearing is formed in the upper and lower ends thereof. On the outer surface of the side wall of the head pipe 3, a connecting seat 3b for integrally welding and fixing the front ends of the main pipes 4 is integrally formed. This connecting seat 3
b is composed of an inner seat 3c and an outer seat 3d, and has a substantially rectangular shape that is substantially the same as the joint end of the main pipe 4 when viewed obliquely rearward, that is, when viewed from the connecting direction of the main pipe 4, that is, a vertically long rectangular shape. There is.

The inner seat 3c has a T-shaped cross section that extends in the axial direction at the center of the head pipe 3 in the vehicle width direction and projects rearward of the vehicle body. The outer seat 3d is on the inner seat 3c.
When the connecting seat 3b and the main pipe 4 are fitted to each other, the gap 3e between the outer seat 3d and the inner seat 3c prevents interference between them when the outer seat 3d and the inner seat 3c are fitted to each other. It is an escape to avoid.

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

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 so that the inner wall 4a and the outer wall 4b of the main pipe 4 are located inside the inner seat 3c and outside the outer seat 3d of the connecting seat 3b, respectively.
Fit with b. When 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 in the vehicle longitudinal direction so as to overlap each other by a predetermined dimension. Next, in this state, main pipe 4
If the fillet welding is performed on the connection seat 3b and the connecting seat 3b, the welding of the two is completed.

As described above, in the frame 2 of the present embodiment, the head pipe 3 has the connecting seat 3 having substantially the same shape as the joint end of the main pipe 4.
Since b is formed, the two can be positioned by fitting them together and pressing from the outside, and the positioning can be performed easily and surely as compared with the conventional one in which the main pipe is butted against the head pipe. Also, in this case, the two are positioned in a state where they overlap each other by a predetermined size, so fillet welding can be easily performed, and as a result, the joining strength is higher than that of the conventional one in which the main pipe is simply butted against the head pipe. Is improved.

In addition, in the above-mentioned embodiment, in order to enable the fitting of the connecting seat 3b and the main pipe 4, the escape, that is, the gap 3e is provided in the connecting seat 3b. You may form in.

[Advantages of the Invention] As described above, according to the frame of the motorcycle of the present invention, the head pipe is formed with the connecting seat having substantially the same shape as the joint end of the main pipe, and both are fitted together. ,
There is an effect that positioning at the time of welding can be performed easily and surely, and as a result, there is an effect that the joint strength can be improved.

[Brief description 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 a joined state of a head pipe and a main pipe thereof, and FIG. 3 is a sectional view taken along line III-III of FIG. Fourth
The figure shows the head pipe of the above-mentioned embodiment, and FIG. 4 (a) is a half sectional plan view thereof, FIG. 4 (b) is a side view thereof, and FIG. 4 (c).
Is a rear view thereof, and FIG. 5 is a side view of a motorcycle to which the above embodiment is applied. In the figure, 1 is a motorcycle, 2 is a frame, 3 is a head pipe, 3b is a connecting seat, 3c is an inner seat, 3d is an outer seat, 4 is a main pipe, 4a is an inner wall, 4b is an outer 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. A rear arm bracket for pivotally supporting a rear arm at a rear end of the main pipe by fixing front ends of a pair of left and right main pipes to a steering head pipe (hereinafter referred to as a head pipe) pivotally supporting a front fork. In a motorcycle frame in which the rear arm bracket and the front portion of the main pipe are fixedly connected to each other by a down tube below the main pipe, the main pipe is formed in a rectangular tube shape having a vertical cross section, The head pipe is made of an aluminum alloy casting, and a connecting seat having substantially the same shape as the joint end of the main pipe is provided on the head pipe 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 are connected to each other. The main pipe and the connecting seat are fitted so that they come into contact with the inner surface of the inner seat and the outer surface of the outer seat, and both are welded and fixed. Motorcycle frames.