JP2566881Y2 - Motorcycle frame headpipe - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The invention relates to improvement of a head pipe of a motorcycle frame.

(Prior art) The motorcycle is provided with a bowl support at the upper and lower ends of a head pipe at a front end of a frame, bearings are inserted, and a steering shaft of a front fork is rotated to be steerable.
It is attached to the head pipe. The head pipe is usually
As shown in FIG. 3, the upper pipe tray receiving portion B is welded to the upper end of the head pipe A, and the lower ball tray receiving portion C is welded to the lower end thereof. The down tube E is welded.
In addition, as shown in FIG. 4, the upper and lower ends of the head pipe F may be expanded to form an upper bowl receiving portion G and a lower bowl receiving portion H. Further, there is also a type in which a bowl receiving portion is formed on the inner periphery of an end, and the bowl receiving portion is fitted at the center with the bowl receiving portion facing up and down and welded. For example, JP-A-55-7797
No. 5, JP-A-63-4887.

(Problems to be Solved by the Invention) As shown in FIG. 3, the upper pipe end of the head pipe A is welded to the upper bowl receiving part B and the lower bowl receiving part C by welding at two places. Therefore, it is difficult to obtain accuracy, and the number of parts is large, which is troublesome. In addition, as shown in FIG. 4, the upper and lower trays G and H are provided above and below the head pipe F by expanding the head pipe F. It is necessary to use a thick one, and it becomes heavy. In addition, when the ball tray receiving part formed at the end is welded by fitting the ball tray receiving part upward and downward at the center, the rigidity of the lower bowl receiving part receiving a large load is insufficient. is there.

In view of the above, the object of the present invention is to provide a motorcycle frame head pipe that can maintain the strength of the lower bowl support portion and can easily weld the upper tube while maintaining the lightweight and rigidity. I do.

(Means for Solving the Problems) In order to achieve the above object, a head pipe of a motorcycle frame according to the present invention is a straight tubular head pipe having a uniform outer diameter d1 through which a steering shaft of a motorcycle is inserted. In the head pipe of the motorcycle frame, which is provided with an upper bowl receiving part 2 at an upper end and a lower bowl receiving part 3 at a lower end with respect to the main body 1, the upper bowl receiving part 2 is It is formed integrally with the upper end of the head pipe main body 1 so as to have the same outer diameter d1 as the head pipe main body 1 and to have a thickness t2, t3 larger than the thickness t1 of the head pipe main body 1, The receiving portion 3 has an outer diameter d2 larger than the upper bowl receiving portion 2 and is separated from the head pipe main body 1 so as to have thicknesses t4 and t5 larger than the thickness t1 of the head pipe main body 1. Formed in the lower bowl support 3 is what was welded to the bottom end of the head pipe body 1.

(Operation) As described above, in the present invention, the head pipe main body 1
The outer diameter can be uniformly increased from the upper end to the lower end, and the thickness can be reduced. The lower bowl counter receiving section 3 which receives a large load from the upper bowl counter receiving section 2 is individually made to have a large thickness and strength, and is welded to the lower end of the head pipe main body 1, so that it is lightweight and rigid as a whole. The precision can be easily obtained with only one welding point. Further, since the upper portion of the head pipe main body 1 has the same diameter, the shape of the abutting surface of the upper tube welded near the upper end is simple, and the welding operation is facilitated.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1 and FIG.

The head pipe main body 1 has an upper bowl support portion 2 formed on the inner surface of the upper end so as to protrude inward by batting. The thicknesses t2 and t3 of the upper bowl receiving portion 2 are set to values (t1 <t3 <t2) larger than the thickness t1 of the head pipe body 1. For this reason, since the head pipe main body 1 can be uniformly thickened in outer diameter including the upper bowl receiving part 2 and can be thinned, it can be thin and light while obtaining rigidity with a thick cross section. The lower bowl receiving portion 3 is formed separately from the head pipe main body 1 and has thicknesses t4 and t5 larger than the thickness t1 and the outer diameter d1 of the head pipe main body 1. Then, the lower bowl receiving portion 3 is welded by abutting against the lower end of the head pipe main body 1. The lower bowl receiving part 3 can be made stronger than the upper bowl receiving part 2, and since there is only one welding point, the accuracy of the head pipe main body 1 can be easily obtained. The head pipe main body 1 is welded by abutting the front end of the upper tube 4 on the upper portion and welding the upper end of the down tube 5 on the lower portion.

As described above, in the head pipe of this embodiment, the upper bowl receiving portion 2 is not larger in diameter than the head pipe main body 1 and has a uniform outer diameter as a whole, so that the front end of the upper tube 4 is connected to the upper end of the head pipe. The shape of the abutment surface can be simplified even in the case of butt welding nearby, and the welding operation can be simplified.

(Effects of the Invention) As described above, since the invention is configured as described above, the head pipe can be made thin and lightweight while maintaining rigidity. The lower bowl receiving portion 3 can be made separately and strong, and the welded portion can be formed with high precision at one location of the head pipe body 1 and the lower bowl receiving portion 3. Further, since the head pipe body 1 has a uniform outer diameter, the shape of the butt portion of the upper tube can be simplified even when the front end of the upper tube is butt welded near the upper end of the head pipe, and the welding operation is also simplified. Become.

[Brief description of the drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is a partially longitudinal front view of a head pipe, FIG. 2 is a perspective view of an entire frame, and FIG. 3 is a conventional head pipe. FIG. 4 is a partial longitudinal front view of a head pipe showing another conventional example. 1 ... Head pipe body, 2 ... Upper bowl receiver, 3 ... Lower bowl receiver, t1 ... Head pipe body thickness, t2, t3 ... Thickness of upper bowl receiver, t4, t5 ... Lower bowl Thickness of pan support, d
1 ... Outer diameter of upper bowl support, d2 ... Outer diameter of lower bowl support

Claims (1)

(57) [Scope of request for utility model registration] 1. A straight tubular head pipe body 1 having a uniform outer diameter d1 through which a steering shaft of a motorcycle is inserted. An upper bowl receiving portion 2 is provided at an upper end and a lower bowl receiving portion is provided at a lower end. In the head pipe of the motorcycle frame provided with the receiving portions 3, the upper bowl receiving portion 2 has the same outer diameter d 1 as the head pipe body 1 and is larger than the thickness t 1 of the head pipe body 1. The lower pipe tray receiving part 3 has an outer diameter d2 larger than that of the upper bowl receiving part 2 and has a thickness t2, t3. Thickness t1 of pipe body 1
A motorcycle characterized in that it is formed separately from the head pipe main body 1 so as to have larger wall thicknesses t4 and t5, and the lower bowl support portion 3 is welded to a lower end portion of the head pipe main body 1. Head pipe for frame.