JPH11165682A - Vehicle body frame for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle body frame for a motorcycle with light weight, high rigidity and excellent productivity. SOLUTION: A head pipe 1 and a pair of rear arm brackets 2, 2 of the right and left are constituted of die-cast molded products made of an aluminum alloy which involve jointing parts 11, 21 for main frame, respectively. A pair of right and left main pipes 3, 3 are constituted of extrusion-molded products made of an aluminum alloy having a long rectangular cross section and involving reinforcing walls 31 extending over right and left side walls 30, 30 in the inside. At the time of die-cast molding of the head pipe 1 and the rear arm bracket 2, both the right and left end parts of the respective main pipes 3 are cast into the corresponding jointing parts 11, 21. At this time, even if large pressurizing force due to molten metal pressure acts on the right and left side walls of the main pipe 3, it is possible to prevent the main pipe 3 from being collapsed by the reinforcing walls 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a head pipe,
The present invention relates to a body frame for a motorcycle comprising a pair of left and right rear arm brackets pivotally supporting a rear frame, and a pair of left and right main pipes connecting a head pipe and left and right rear arm brackets.

[0002]

2. Description of the Related Art Conventionally, as a body frame of this type, in order to increase rigidity and reduce weight, a main pipe is formed of an aluminum alloy pipe having a vertically long rectangular cross section.
It is known that the head pipe and the rear arm bracket are each formed of an aluminum alloy die-cast product (Japanese Patent Application Laid-Open No. 62-34880, Japanese Patent Publication No. 7-1004).
No. 65). In this case, the front ends of the left and right main pipes are welded to the head pipe, and the rear arm brackets are welded to the rear ends of the main pipes to assemble the body frame.

According to Japanese Utility Model Publication No. 38-9501, a backbone-type body frame in which main pipes are not provided on the left and right sides, but a head pipe and a rear arm bracket are each made of an aluminum alloy having a connecting portion for the main pipe. Is also known in which a front end and a rear end of a main pipe formed of a round pipe are cast into each joint when die-casting a head pipe and a rear arm bracket.

[0004]

When the frame is assembled by welding as in the former prior art, the welding is troublesome and productivity is deteriorated. Therefore, using the latter conventional technique, the front ends of the left and right main pipes are respectively cast into a pair of left and right joints for the main pipe integrally formed with the head pipe, and the left and right rear arm brackets are integrally formed. It is conceivable that the rear ends of the left and right main pipes are respectively cast into the joints for pipes to eliminate welding and improve productivity.

However, in such a cast body frame, if the main pipe is made of an aluminum alloy pipe having a vertically long rectangular cross section for increasing rigidity and reducing the weight, the pressure applied to the molten metal during die casting is reduced. Excessive force acts on the left and right side walls of the main pipe, which are the long sides of the cross section, and the main pipe is crushed in the lateral direction. On the other hand, if the main pipe is made of a round pipe, it will be able to withstand the molten metal pressure. When the main pipe is a round pipe made of aluminum alloy, the bending rigidity of the main pipe in the vertical direction is insufficient, and the rigidity of the body frame cannot be increased.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a body frame of a type in which a main frame is divided into right and left, which is excellent in productivity and lightweight and rigid.

[0007]

Means for Solving the Problems In order to solve the above problems,
The present invention relates to a motorcycle body frame comprising a head pipe, a pair of left and right rear arm brackets pivotally supporting a rear frame, and a pair of left and right main pipes connecting the head pipe and the left and right rear arm brackets. Each main pipe is composed of an extruded aluminum alloy product having a vertically long rectangular cross-section and a reinforcing wall straddling the left and right side walls inside, and the head pipe is composed of an aluminum alloy die-cast molded product. The front ends of the left and right main pipes are cast into a pair of left and right main frame joints that are integrally formed with the head pipe, and each rear arm bracket is made of an aluminum alloy die-cast product. The rear end of each main pipe is cast into a joint for the main frame to be integrally molded.

Since each end of the main pipe is cast into each joint at the time of die-casting the head pipe and the rear arm bracket, welding is not required, and productivity is improved.
Also, even if a large force acts on the left and right side walls of the main pipe due to the pressure applied to the molten metal during die casting,
The reinforcement wall straddling the left and right side walls prevents the main pipe from collapsing in the lateral direction. Therefore, even in a cast-in type vehicle body frame, an aluminum alloy pipe having a vertically long rectangular cross section can be used as the main pipe, and rigidity can be increased and weight can be reduced.

By the way, it is necessary to close both front and rear ends of each main pipe so that molten metal does not flow into each main pipe during die casting. In this case, if the front and rear ends of each main pipe are cast into each joint while the lid plates larger than the cross-sectional shape of the main pipe are fixed to the front and rear ends of each main pipe, the lid plate becomes an anchor and Since the coupling strength of the main pipe is improved, it is advantageous in increasing the strength of the body frame.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A shows a vehicle body frame for a motorcycle.
And a pair of left and right rear arm brackets 2 and 2 for pivotally supporting a rear arm (not shown), and a pair of left and right main pipes 3 and 3 connecting the head pipe 1 and the left and right rear arm brackets 2 and 2. .

The head pipe 1 is made of an aluminum alloy die-cast product, and extends laterally outward from the main body having a hole 10 through which a steering shaft of a front fork (not shown) is inserted. A pair of left and right joints 11 for the main pipe 3, a plurality of ribs 12 for reinforcing the joints 11, 11, and an engine hanger 13 extending downward from each joint 11 are integrally formed. I have.

Each of the rear arm brackets 2 is also formed of a die-cast product made of aluminum alloy, and has a connecting portion 21 for the main pipe 3 extending forward from the upper end of the main body having a pivot mounting hole 20 for the rear arm. A mounting part 22 of the suspension member for the rear arm extending inward in the horizontal direction from the upper part of the main body, and a mounting part 23 of the main stand extending inward in the horizontal direction from the lower part of the main body are integrally formed.

Each of the main pipes 3 is formed of an extruded product made of an aluminum alloy, and the front portions of the left and right main pipes 3 are curved inward in the horizontal direction as shown in FIG. Then, the left and right main pipes 3 and 3 are attached to the mold having the cavity for the head pipe 1 and the cavities for the left and right rear arm brackets 2 and 2 at the front and rear ends thereof for the joints 11 and 21 of each cavity. The head pipe 1 and the rear arm brackets 2 and 2 are die-cast with molten aluminum alloy being injected into each cavity at a high pressure (for example, 700 kg / cm ² ). According to this, the left and right main pipes 3, 3 are connected to the pair of left and right joints 11, 11 of the head pipe 1.
3, the rear ends of the left and right main pipes 3, 3 are cast into the joints 21, 21 of the left and right rear arm brackets 2, 2, and the vehicle body frame is assembled only by die casting.

As shown in FIG. 1B, the cross-sectional shape of each main pipe 3 is a vertically long rectangle as shown in FIG. 1 (B). Will be crushed. Therefore,
In the present embodiment, when extruding the main pipe 3,
A pair of upper and lower reinforcing walls 31, 31 straddling the left and right side walls 30, 30 are integrally formed inside the main pipe 3 so that the main pipe 3 can be prevented from being crushed by the molten metal pressure by the reinforcing walls 31, 31. . The number of the reinforcing walls 31 is 2
It is not limited to individual pieces, and may be set appropriately according to the vertical dimension of the main pipe 3 and the molten metal pressure.

In order to prevent the molten metal from flowing into the main pipe 3 during die casting, the front and rear ends of each main pipe 3 are closed with the lid plate 4 at each end. Are cast into the joints 11 and 21. In the present embodiment, a cover plate 4 larger than the cross-sectional shape of the main pipe 3 is used, and this is fixed to each of the front and rear ends of the main pipe 3 by welding or the like. According to this, the front and rear ends of the main pipe 3 are connected to the respective connecting portions 1.
When cast into 1,21, lid plate 4 becomes an anchor,
The connection strength of the main pipe 3 to the connection portions 11 and 21 is increased, and the strength of the body frame can be further increased.

[0016]

As is apparent from the above description, according to the present invention, a cast-in type vehicle body frame can be obtained using aluminum alloy pipes having a rectangular cross section as the left and right main pipes. The weight can be reduced and the rigidity can be increased, and productivity can be improved.

[Brief description of the drawings]

FIG. 1A is a perspective view of an example of the frame of the present invention,
(B) Sectional view taken along the line IB-IB of FIG.

FIG. 2 is a plan view seen from the direction of arrow II in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Head pipe 11 Connection part 2 Rear arm bracket 21 Connection part 3 Main pipe 30 Side wall 31 Reinforcement wall

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Miyamoto 1-10-1 Shinsayama, Sayama City, Saitama Prefecture Inside Honda Engineering Co., Ltd. (72) Inventor Takeshi Akutsu 1-10-1 Shinsayama, Sayama City, Saitama Honda Engineering Incorporated (72) Inventor Hiroshige Iwase 1-4-1 Chuo, Wako-shi, Saitama Pref., Ltd.In Honda R & D Co., Ltd. Honda Technical Research Institute

Claims (2)

[Claims] 1. A body frame for a motorcycle comprising a head pipe, a pair of left and right rear arm brackets pivotally supporting a rear frame, and a pair of left and right main pipes connecting the head pipe and the left and right rear arm brackets. Each of the main pipes is made of an aluminum alloy extruded product having a vertically long rectangular cross section and a reinforcing wall extending between the left and right side walls inside, and the head pipe is made of an aluminum alloy die cast product. The front ends of the left and right main pipes are cast into a pair of left and right joints for the main frame integrally formed with the head pipe, and each rear arm bracket is made of an aluminum alloy die-cast product. Wherein the rear end of each main pipe is cast into a joint for the main frame that is integrally molded with the main frame. The vehicle body frame for a wheel vehicles. 2. The front and rear ends of each main pipe are cast into respective joints with lid plates larger than the cross section of the main pipe fixed to the front and rear ends of each main pipe. Body frame for motorcycles.