JPH0684158B2 - Motorcycle frame - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a motorcycle frame, and more particularly to improvement of joint strength between a head pipe and a main pipe thereof.

[Conventional technology]

There are various types of frames for motorcycles, for example,
A head pipe that pivotally supports the front fork 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 main pipes. 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 59-15
See 6868).

[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. For example, in the frame according to the above-mentioned prior application,
In order to improve the joint strength, the longitudinal length of the front end portion of the main pipe is formed to be substantially the same as that of the head pipe.

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 capable of further improving the joint strength between the main pipe and the head pipe as compared with the frame of the above-mentioned prior application.

[Means for solving problems]

The present invention, in a frame of a motorcycle, a main pipe is formed in a rectangular tube shape having a vertically long transverse cross section, the head pipe is made by casting, and a connecting seat is integrally provided at a center portion of the head pipe in a vehicle width direction, Connect the connecting seat to the upper part of the head pipe,
A top wall portion and a bottom wall portion each of which extends from the lower portion so as to project rearward and expands to include the vehicle center line in a plan view,
A vertical wall portion that extends substantially parallel to the head pipe and extends so as to intersect the vehicle center line in a plan view, and integrally connects the rear end portions of the top wall portion and the rear wall portion, The inner wall of the left and right main pipes is welded to the left and right end faces of the vertical wall in the vehicle width direction. Here, the larger the protruding size of the connecting seat, the larger the required joining strength.

[Action]

In the present invention, since the connecting seat is composed of the top wall portion, the bottom wall portion, and the vertical wall portion connecting these rear end portions, as shown in FIG. 3, the connecting seat is a head pipe. Since the box-shaped structure is formed, the rigidity of the connecting seat itself can be significantly improved.

In addition, since the inner wall of the left and right main pipes are welded to the left and right end faces of the vertical wall located at the position rearward from the head pipe, the above vertical wall connects the left and right main pipes to the rear from the head pipe. Since it acts as a cross member that joins at a distance from each other, the strength of the joining portion between the head pipe and the main pipe can be greatly 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. This frame 2
The front ends of a pair of left and right main pipes 4, 4 are fixed to the head pipe 3, a 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 part of the main pipe 4 are fixed. Are connected by a down tube 6.

A front fork 8 supporting a front wheel 7 is pivotally supported on the head pipe 3. Further, the front ends of the seat rails 9 are fixed on the left and right main pipes 4, 4 respectively, and the back stays 10 are arranged and fixed between the rear portions of the seat rails 9 and the rear arm brackets 5, respectively. There is. Further, side members 11 are arranged and fixed between the front portions of the seat rails 9 and the outside of the back stay 10 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 13c for covering them are mounted on the main pipe 4.

In the middle of the rear arm bracket 5, a rear arm 15 supporting a rear wheel 14 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 engine
The lower part of the front side of 16 is fixed to the down tube 6, and the upper part of the rear side 16a is fixed to the rear arm bracket 5.

As shown in FIG. 1, the left and right main pipes 4, 4 are
The front part thereof is widened outward in the vehicle width direction with the head pipe 3 as the center, the central part is bent so as to be substantially parallel, and the rear part is linearly extended. For each main pipe 4, an inner wall 4a and an outer wall 4b formed by bending an aluminum alloy plate into a U-shaped cross section are prepared, and the opening of the inner wall 4a is inserted into the opening of the outer wall 4b. The rectangular tube shape is formed by welding the overlapping portions of both.
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 welding and fixing the front ends of the respective main pipes 4 is integrally formed so as to project. The connecting seat 3b is composed of an inner seat 3c and an outer seat 3d, and has a rectangular shape that is diagonally rearward, that is, substantially the same shape as the joint end of the main pipe 4 when viewed from the connecting direction of the main pipe 4, that is, a vertically long rectangular shape. It has become.

The outer seat 3d extends vertically along the left and right outer peripheral surfaces of the head pipe 3. The inner seat 3c connects the top wall portion 3h extending rearward from the vicinity of the upper end of the head pipe 3, the bottom wall portion 3f extending rearward from the vicinity of the lower end, and the rear end portions of both wall portions 3h, 3f. It is composed of a vertical wall portion 3i.

The top wall portion 3h and the bottom wall portion 3f have a shape that extends in a plane that is substantially orthogonal to the axis of the head pipe 3 and that includes the vehicle center line in plan view. The vertical wall 3c has a shape that extends substantially parallel to the head pipe axis and extends in a plane orthogonal to the vehicle center line in plan view, and is separated rearward from the rear portion of the outer peripheral surface of the head pipe 3. positioned.
Further, the vertical wall 3c and the rear portion of the outer peripheral surface of the head pipe are ribs extending in the vertical direction (head pipe axial direction) at the center in the vehicle width direction.
The ribs 3g and the vertical walls 3c are connected by 3 g, and have a T-shape when viewed in cross section.

And to the connecting seat 3b consisting of the inner seat 3c and the outer seat 3d,
The tip of the main pipe 4 is welded and connected. In this case, the outer surfaces of the inner walls 4a of the left and right main pipes 4, 4 are welded and fixed to the left and right end surfaces of the vertical wall 3i of the inner seat 3c, and the ceiling wall 3
h, the inner surfaces of the top wall and the bottom wall of the main pipe 4 are welded and fixed to the bottom wall portion 3f, and the inner surface of the outer wall 4b is welded and fixed to the outer seat 3d. 3e is a vertical wall 3i, a top wall 3h, and a bottom wall 3f.
It is a gap provided in the boundary portion between and, and the tip portion of the main pipe 4 is inserted into this gap. In other words, the inner seat 3c of the connecting seat 3b connects the main pipe 4 to the head pipe 3
It acts as a cross member that joins immediately after. In this way, the left and right main pipes 4, 4 above
Are integrally fixedly connected to each other through the connecting seat 3b and the side wall of the head pipe 3, and the joint between the head pipe 3 and the left and right main pipes 4, 4 has a box-type structure.

As described above, in the frame 2 of the present embodiment, the head pipe 3 is formed with the connecting seat 3b, and the inner seat 3c thereof is made to project largely toward the rear of the vehicle body.
Since the inner side wall 4a of the inner wall 3a is welded, the inner seat 3c acts as a cross member, and the left and right main pipes 4 are
4a comrades are integrally fixed by this inner seat 3c, and this joint has a box-shaped structure, and the joint strength is greatly improved as compared with the case where the main pipe 4 is simply abutted against the head pipe 3 and welded. ing.

In addition, the connecting seat 3b is composed of an inner seat 3c and an outer seat 3d.
3c is a flat top wall portion 3h and a bottom wall portion 3f that extend rearward from the vicinity of the upper end and the lower end of the head pipe 3 and a vertical wall portion that joins the rear ends of the both wall portions 3h, 3f. Since the vertical wall portion 3i and the head pipe outer peripheral rear portion are joined by the rib 3g, the rigidity of the connecting seat 3b itself can be significantly improved. Further, since the vertical wall portion 3i is located rearward of the head pipe 3, the main pipe 4 having a width as wide as the head pipe diameter can be joined to the head pipe 3 without any trouble.

When welding the front end of the main pipe 4 to the head pipe 3, connect the front end of the main pipe 4 to the connecting seat.
It is positioned by simply fitting it in 3b and pressing it from the outside in the vehicle width direction, so that the welding operation becomes easy and reliable.

〔The invention's effect〕

As described above, according to the frame of the motorcycle according to the present invention, the connecting seat is formed integrally with the head pipe by projecting it to the rear of the vehicle body, and the inner side wall of the main pipe is welded to the connecting seat. The main pipe can be firmly fixed and coupled through the head pipe and the connecting seat, and the joint strength between the main pipe and the head pipe can be improved, and the connecting seat can be connected to the top wall portion, the bottom wall portion, and both walls. Since it is composed of a vertical wall part that integrally joins the rear ends of the parts, there is an effect that the rigidity of the connecting seat itself can be improved. Furthermore, since the vertical wall part is located rearward from the head pipe, it is wide. It has the effect of joining the main pipe without any problems.

[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, FIG. 4 (a) is a half sectional plan view thereof, FIG. 4 (b) is a side view thereof, FIG. 4 (c) is a rear view thereof, and FIG. It is a side view of a motorcycle to which the above-mentioned embodiment is applied. In the figure, 1 is a motorcycle, 2 is a frame, 3 is a head pipe, 3c is an inner seat (connecting 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, 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 frame of a fixed motorcycle, the main pipe is formed in a rectangular tube shape having a vertically long transverse cross section, the head pipe is made of cast metal, and a connecting seat is integrally provided at a center portion of the head pipe in a vehicle width direction, The seat extends from the upper part and the lower part of the head pipe so as to project rearward, and extends in parallel with the head pipe and the bottom wall part that expands to include the vehicle center line in a plan view, and It extends so as to intersect the vehicle center line in a plan view, and is constituted by a vertical wall portion that integrally connects the rear end portions of the top wall portion and the bottom wall portion, and the vertical wall portion has a vehicle width direction left, On the right edge Kihidari, motorcycle frame, characterized in that welding the inner wall of the right main pipes.