JP2574673Y2 - Motorcycle frame - Google Patents

Description

[Detailed description of the invention]

[Purpose of the invention]

[0002]

BACKGROUND OF THE INVENTION The present invention relates to a motorcycle frame.

[0003]

2. Description of the Related Art As shown in FIG. 5, a frame of a motorcycle has a main tube 2 at a rear upper portion of a head pipe 1 for supporting an upper end shaft of a front fork for supporting a front wheel.
However, the down tube 3 is welded to the lower portion, and the lower ends of the main tube 2 and the down tube 3 are connected by two left and right body tubes 4 to form a loop shape. There is a semi-double cradle type frame structure to which ancillary equipment such as an engine is attached. The seat rail 6 is located at the rear of the main tube 2.
And a rear portion thereof is supported by the body tube 4 by a tube 7.

The left and right body tubes 4, 4 are welded to the left and right side surfaces of the rear portion of the down tube 3 as shown in FIG. 6, and the left and right body tubes 4, 4 are welded with reinforcing members 8 to increase rigidity. I have it.

[0005]

[Problems to be solved by the invention] In the above conventional structure,
The rigidity of the down tube 3 is increased and the body tube 4,
The down tube 3 made of a square pipe is used to facilitate the butt welding of 4, but in the case of the square pipe, there is a problem that the stress is easily concentrated on the corner portion, and the driving of the engine is also performed in a round pipe. In the case of a square pipe, it is difficult to disperse, so that cracks are likely to occur, and the reinforcing material 8 blocks the space and makes the appearance unsightly.

According to this invention, the rigidity of the down tube consisting of a square pipe is increased, and at the same time, the torsional rigidity of the body tube is increased, so that the entire frame can have a strong structure.
An object of the present invention is to provide a motorcycle frame that takes up no space and has a clean appearance. [Structure of device]

[0007]

In order to achieve the above-mentioned object, the motorcycle frame according to the present invention has left and right body tube ends on the left and right sides of a rear portion of a down tube made of a square pipe. In a welded semi-double cradle-type frame, a lean hosement having a sealing surface for sealing the entire rear end opening of the down tube is provided. The left and right legs of the lean hosement are welded along the longitudinal axis of the body tube.

[0008]

Since the opening at the rear end of the down tube made of a square pipe is sealed by the sealing surface, intrusion of earth and sand into the pipe is prevented. Further, since the joint between the down tube and the body tube is integrally connected by the lean hosement, the rigidity of the down tube and the body tube is increased, and the strength of the entire frame is increased. And, since the legs of the lean hosement are welded along the inside of the body tube, there are no extra protrusions, and there is no increase in weight and no reduction in appearance.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a motorcycle frame according to the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 and 2, the down tube 10 whose front end is welded to the head pipe is formed of a square pipe, and its rear end is open. End portions of the left and right body tubes 11, 11 are butted and welded to left and right side surfaces 10a, 10a at a rear portion of the down tube 10.

The lean hosement 12 has a sealing surface 13 having an area covering the opening 10b at the rear end of the down tube 10. On both sides of the sealing surface 13, the inner surfaces of the body tubes 11, 11 are provided. The legs 14, 14 having a semicircular cross section are integrally provided. This sealing surface 13
Is provided with a drain hole 15 which also serves to reduce the weight. FIG. 3 shows a case where the body tubes 11, 11 are also square pipes. In this case, the legs 14,
As shown in FIG. 4, reference numeral 14 denotes a flat plate which is in contact with the inner surfaces of the body tubes 11, 11.

Accordingly, the down tube 1 made of a square pipe
Since the opening 10b at the rear end of the zero tube 10 is sealed by the sealing surface portion 13 of the lean hosement 12, earth and sand can be prevented from entering the down tube 10 from the opening 10b. Also, the down tube 10 and the body tubes 11, 1
1 is integrally joined by the lean hosement 12, the rigidity of the down tube 10 and the body tubes 11, 11 is increased, and the strength of the entire frame is increased. Since the leg portions 14, 14 of the lean hosement 12 are welded along the inside of the body tubes 11, 11, the rear end of the down tube 10 and the body tube 11,
No extra protrusions are formed between the wires 11 and the layout of equipment and accessories is not affected, and the weight and appearance are not increased.

[0013]

As described above, in the motorcycle frame according to the present invention, the semi-double cradle is formed by welding the ends of the left and right body tubes to the left and right sides of the rear portion of the down tube formed of a square pipe. In the mold frame, a lean hosement having a sealing surface portion for sealing the entire rear end opening of the down tube is provided, and the lean hosement is provided along the left and right inner surfaces of the body tube from both sides of the sealing surface portion. The left and right legs of the lean hosement are welded along the longitudinal axis of the body tube, so that the lean hosement closes the rear tube opening of the down tube and The tube joint is reinforced, and the torsional rigidity of the body tube can be improved, resulting in a tough frame structure . In addition, the entire rear end opening of the down tube is sealed with the sealing surface of the lean hose so that earth and sand and muddy water can be prevented from entering the down tube,
Rust from inside can be prevented, and durability can be improved. In addition, the lean hosement is welded along the rear end of the down tube and along the left and right body tubes, so there is no extra protrusion and sufficient space for equipment installation can be secured, but there is no obstacle in design, and weight The cost can be reduced without causing an increase.

[Brief description of the drawings]

FIG. 1 is a front view showing a cross section of a right half part showing a main part of the present invention.

FIG. 2 is a view taken in the direction of arrow A in FIG. 1;

FIG. 3 is a perspective view showing a modification of the body tube.

FIG. 4 is a perspective view of a lean hose used in FIG. 3;

FIG. 5 is a side view showing an example of a frame structure to which the present invention is applied.

FIG. 6 shows a conventional technique, and is a view as viewed from B in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Head pipe 2 Main tube 3 Down tube 4 Body tube 6 Seat rail 10 Down tube 11 Body tube 12 Lean hosement 13 Sealing surface part 14 Leg part 15 Drain hole

Claims (1)

(57) [Scope of request for utility model registration] In a semi-double cradle type frame formed by welding ends of left and right body tubes to left and right side surfaces of a rear portion of a down tube formed of a square pipe, a sealing surface portion for sealing an entire rear end opening of the down tube. The lean hosement is provided with the left and right legs connected along the inner surface of the left and right body tubes from both sides of the sealing surface, and the left and right leg side ends of the lean hosement are integrally connected. Is welded along a longitudinal axis of the body tube.