JPH05105162A - Frame front part structure of motorcycle - Google Patents

Abstract

PURPOSE:To provide the frame front part structure of a motorcycle in which the rigidity can be increased by adding a reinforcing plate having a U figure section on the under-side of the upper tube of a frame, the rigidity can be varied by installing or demounting the reinforcing plate, the fundamental shape of the frame can be used in common, and the cost of a welding jig can be reduced. CONSTITUTION:Each reinforcing plate 6 is attached and welding on the front part of an upper tube 3 extended downward in the rearward direction from the upper part of a head pipe 2 at the front edge and both the sides of a down tube 4 extended downward from the lower part of the head pipe 2, and a reinforcing plate 11 which is formed to a U-figure section is welded on the underside of the upper tube 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame front structure for a motorcycle.

[0002]

2. Description of the Related Art A motorcycle frame is often manufactured by welding steel pipes. As shown in FIG. 4, the front part of the frame is attached to the upper part of the head pipe A at the front end by the upper tube B.
The front end of the down tube C is abutted and welded to the lower end of the head pipe A. The upper tube B requires the most rigidity in the frame, and a thick steel pipe is used. Also, head pipe A
Is a front fork with the front wheel suspended and must be mounted with high rigidity. Therefore, a reinforcement plate D is attached along the front portion of the head pipe A and the upper tube B and both side portions of the down tube C for welding. There is.

[0003]

The frame of a motorcycle may be equipped with engines of different sizes. In such a case, the required rigidity value for the frame changes. The thickness of the steel pipe to be used is changed according to the required value of the rigidity of the frame. However, if you do this, the welding jig will change,
There is an inconvenience that the frame cannot be shared and the manufacturing cost becomes high.

In view of this point, the present invention can increase the rigidity of the frame by adding a reinforcing plate having a U-shaped cross section to the lower side of the upper tube of the frame.
It is an object of the present invention to obtain a frame front structure of a motorcycle in which rigidity can be changed by attaching or removing a reinforcing plate, the basic shape of the frame can be shared, and welding jig costs can be reduced.

[0005]

In order to achieve the above object, a frame front structure of a motorcycle according to the present invention comprises a front part of an upper tube extending from an upper part of a head pipe at a front end to a rear lower part and a lower part of the head pipe. This is because reinforcing plates were attached to both sides of the down tube extending downward and welded, and a reinforcing plate formed in a U-shaped cross section was welded to the lower side of the upper tube.

[0006]

The rigidity of the frame can be increased by welding a reinforcing plate having a U-shaped cross section to the lower side of the upper tube, which requires the most rigidity in the frame. Then, a frame having two kinds of rigidity can be obtained by attaching or removing the reinforcing plate, and the basic shape of the frame can be made common. As a result, it is possible to reduce the cost by reducing the number of welding jigs.

[0007]

Embodiments of the present invention will be described below with reference to FIGS. The frame 1 is made by welding a steel pipe, and the front end of the upper tube 3 is abutted and welded to the upper end of the head pipe 2 at the front end where the front fork is attached, and the front end of the down tube 4 is attached to the lower part of the head pipe 2. Butt and weld. Then, the bridge tube 5 is welded between the rear portions of the down tube 4 and the upper tube 3, and the reinforcing pipes 6 are attached to both sides of the head pipe 2, the upper tube 3, and the down tube 4 to weld them, thereby increasing the rigidity of the head pipe 2. There is. The left and right center tubes 7 are welded to the rear end of the upper tube 3 to connect the center fittings 8, and the front ends of the left and right lower tubes 9 are welded to the lower end of the down tube 4. The rear end 9 is welded to the lower end of the center metal fitting 8. The left and right rear tubes 10 are welded to the rear side of the upper tube 3 and the upper ends of the left and right center fittings 8.

Then, a reinforcing plate 11 having a U-shaped cross section and bulging downward is welded to the lower side of the upper tube 3. The reinforcing plate 11 has a shallow front side and a deep rear side. This is because the connecting pipes 13 of the radiators 12 attached to both sides of the left and right reinforcing plates 6 are passed under the front portion of the reinforcing plate 11.
On the lower side of the reinforcing plate 11, a stay 15 for attaching the ignition coil 14 is welded.

By welding the reinforcing plate 11 to the lower side of the upper tube 3, the rigidity of the front portion of the frame 1 can be increased. Then, depending on whether the reinforcing plate 11 is attached or not, two types of frames 1 having different rigidity can be obtained.

[0010]

As described above, since the present invention is constructed as described above, a reinforcing plate having a U-shaped cross section is welded to the lower side of the upper tube, which is the most rigid frame. There are two types of frames with different rigidity depending on whether they are attached or not. Since the basic shapes of the frames are the same in two types and can be produced by one welding jig, the equipment cost can be reduced and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a side view of a main part showing an embodiment of the present invention.

FIG. 2 is a side view of the entire frame showing an embodiment of the present invention.

FIG. 3 is an enlarged sectional view taken along the line AA of FIG. 1 showing an embodiment of the present invention.

FIG. 4 is a side view of a front portion of a frame showing a conventional example.

[Explanation of symbols]

 1 frame 2 head pipe 3 upper tube 4 down tube 6 reinforcing plate 11 reinforcing plate

Claims (1)

[Claims] 1. A reinforcing plate is attached to both sides of an upper tube front part extending downward from the upper part of the head pipe at the front end and a down tube extending downward from the lower part of the head pipe, and welding is performed by attaching reinforcing plates to the lower part of the upper tube. A frame front structure for a motorcycle, wherein a reinforcing plate having a U-shaped cross section is welded.