JPH01226484A - Frame member for motorcycle - Google Patents

Abstract

PURPOSE:To reduce degradation of rigidity and deformation when benmding work is made by employing a rectangular pipe having one sideface formed with projecting or recessed curved face as a frame member. CONSTITUTION:Upper right and left pipes 3 are made of light alloy to have elongated rectangular cross-section, and drawn out into pipes having longitudinal ribs 8 at the inside. Projecting curved face 10 is formmed between the rib 8 and one upper/lower sides 9, while recessed curved face 11 is formed between two ribs 8. When bending work is made such that the sections formed with the projecting and recessed curved faces come to the outside, the deformation is not conspicuous and concentration of stress can be avoided.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a frame material for a motorcycle.

(Prior art and its problems) Generally, a motorcycle frame is made by selecting a steel pipe with a rigidity suitable for the place of use, bending it at appropriate places, and
It is made by welding and joining. However, in sports-type motorcycles, there is a need to improve heavy-duty performance by reducing the weight of the vehicle, so instead of steel pipes, light alloy pipes are used to reduce weight. In the case of light alloy, the material itself lacks rigidity compared to steel, so the pipe material is made thicker or ribs are provided on the inside to strengthen it. Figure 5 shows pipe material A with a rectangular cross section.
In this case, the bending process results in deformation as shown by the two-dot chain line, which not only results in insufficient rigidity, but also makes it noticeably unsightly. Figure 6 shows a vertically long rectangular pipe 1.
In the case where rib B is provided horizontally and integrally between 4A,
In this case as well, when the material is bent, it can be deformed as shown by the two-dot chain line. In order to prevent this, as shown in Fig. 7, a groove C is provided on the outside of the rectangular pipe material to fit inside the pipe B, and the groove C absorbs the deformation when bent. There are some attempts to reduce deformation. For example, Jitsukai 61
See Publication No.-98690.

However, in this case, although the appearance is improved, stress is concentrated in the groove C, making it weaker, and the groove C gets clogged with dust during use, making it unsightly.

(Objective of the Invention) The present invention provides a motorcycle frame material that has a vertically elongated rectangular cross section and has horizontal ribs on the inside, and that exhibits less decrease in rigidity and less noticeable deformation when bent. The purpose is to

(Structure of the Invention) The present invention will be described below with reference to embodiments shown in FIGS. 1 to 4.

1 to 3 show one embodiment of the present invention.

The head pipe 1 at the front end of the frame and the left and right central metal fittings 2 in the center of the frame are welded together using an upper vibe 3 made of pipe material, and the rear pipe 4 of thin pipe material is further welded to the left and right central metal fittings 2. Combine to form a frame. In addition, the front fork 5 is attached to the head pipe, and the left and right center metal fittings 2 are attached.
The front end of the rear hook is pivoted to the front end, and an engine 7 is mounted on the front side of the left and right upper pipes 3 and the left and right center metal fittings 2.

Therefore, the pipe material for the left and right upper pipes 3 is made of J: sea urchin, a light alloy, and has a rectangular cross section with ill length, as shown in Fig. 3.
It has horizontal ribs 8 on the inside and is pulled out into a pipe shape.
A curved surface of a convex arc 10 is formed between the upper edge of one side and the edge 9 and the rib 8, and a curved surface of a concave arc 11 is formed between the two ribs 8.

FIG. 4 shows another embodiment of the invention. In this case, the pipe material for the left and right upper pipes 3 is made of light alloy and has a vertically elongated rectangular cross section, with a rib 8 installed horizontally on the inside, and ribs on the upper and lower sides 9 of one side. 8 is formed into a curved surface of a convex arc 10. The other parts are the same as those shown in FIGS. 1 to 3.

(Operation of the invention) The left and right upper pipes 3 are welded to the head pipe 1 with their front ends centered, made 11 wide so that the engine 7 can fit in the center, and their rear ends welded to the left and right center fittings 2. , bending is required. The bending process is performed so that the portion formed by the curved surfaces of the convex arc 10 and the concave arc 11 on one side is on the outside. The bent part can be deformed, and the curvature of the curved surface of the convex arc 10 and concave arc 11 changes, but since the curved surface has been formed from the beginning, the deformation is not noticeable, and stress is concentrated due to the bending process. Since it is possible to avoid the parts where the parts are bent, there is less decrease in rigidity.

〔Effect of the invention〕

As explained above, the present invention is a pipe having a vertically elongated rectangular cross section and integrally provided with one or two ribs on the inside. Since the space between the ribs is formed into a convex or concave curved surface and used as a frame material for a motorcycle, the curvature changes and deforms when it is bent, making the deformation less noticeable.

In addition, it is possible to avoid areas where stress is concentrated during bending, resulting in less reduction in rigidity and increased durability.

[Brief explanation of the drawing]

1 to 3 show one embodiment of the present invention, FIG. 1 is a side view of a motorcycle frame using the frame material of the present invention, FIG. 2 is a plan view of the same, and FIG. 4 is a sectional view of a frame material showing another embodiment of the present invention, and FIGS. 5 to 7 are sectional views of a frame material showing conventional examples. 3... Pipe, 8... Rib, 9... Upper side and lower side, 10... Convex circular arc, 11... Concave circular arc.

Claims (1)

[Claims] A pipe with a vertically elongated rectangular cross section and one or two horizontal ribs on the inside, with one side between the top and bottom sides and the ribs, or between the two ribs with a convex or concave arc. A motorcycle frame material formed into a curved surface and used as a motorcycle frame material.