Vehicle body frame for motorcycle

• US 20040154852A1
• Filed: 04/05/2004
• Published: 08/12/2004
• Est. Priority Date: 12/28/2001
• Status: Active Grant

• Current Assignee: Yamaha Hatsudoki Kabushiki Kaisha (Yamaha Corporation)
• Original Assignee: Yamaha Hatsudoki Kabushiki Kaisha (Yamaha Corporation)
• Inventors: Yamaoka, Hiroshi, Miyashiro, Shidehiko, Katsura, Takehisa, Fukuda, Takayoshi, Shiraishi, Takushiro, Yokomizo, Sin, Unno, Norikazu
• Granted Patent: US 7,073,617 B2
• Time in Patent Office: Days
• US Class Current: 180/219
• CPC Class Codes: B62K 11/04 characterised by the engine being between front and rear wheels
• CPC Class Codes: B62K 19/12 having cast members

Abstract

In a body frame for a motorcycle mounted with an engine unit 11 and provided with a main frame 2a by which a front fork 4 and rear arms 7 are supported, the main frame 2a includes: a head pipe unit 20 which extends obliquely downward to a rear of a vehicle from a head pipe 3 and so as to expand in a vertical direction; a down frame 21 which is connected to a front part at lower end of the head pipe unit 20; and left and right rear arm brackets 10 which are stretched and connected to a rear end of the down frame 21 and a rear part at lower end of the head pipe unit 20, and the head pipe unit 20 is an aluminum die-cast molded product, and the down frame 21 and the left and right rear arm brackets 10 are aluminum forged molded products.

Claims

1. A body frame for a motorcycle mounted with an engine unit and provided with a main frame by which a front fork and rear arms are supported, characterized in that the main frame comprises:

a head pipe unit which extends obliquely downward to a rear of a vehicle from a head pipe and so as to expand in a vertical direction;

a down frame which is connected to a front part at lower end of the head pipe unit to extend downward and further extends to the rear of the vehicle; and

rear arm brackets which are stretched and connected to a rear end of the down frame and a rear part at lower end of the head pipe unit, at least one of which is an aluminum die-cast molded product and the rest are aluminum forged molded products, or all of which are aluminum forged molded products.

2. A body frame for a motorcycle according to claim 1, characterized in that the head pipe unit is an aluminum die-cast molded product or an aluminum forged molded product, and the down frame and the rear arm brackets are aluminum forged molded product.

3. A body frame for a motorcycle according to claim 1 or 2, characterized in that a sectional shape of the head pipe unit, the down frame, and the rear arm brackets is an opened section.

4. A body frame for a motorcycle according to any one of claims 1 to 3, characterized in that the head pipe unit is a head pipe unit generally I-shaped in a cross section thereof which is constituted by integrally forming an upper main frame section with a rectangular shape in a section thereof extending obliquely downward to the rear of the vehicle from the upper end of the head pipe, a lower main frame section with a rectangular shape in a section thereof extending downward to the rear of the vehicle from the lower end of the head pipe, and gusset sections of a vertical wall shape which closes a space surrounded by the head pipe and the upper and lower main frame sections and whose vehicle width dimension is set smaller than a vehicle width dimension of the respective main frame sections.

5. A body frame for a motorcycle according to any one of claims 1 to 4, characterized in that the down frame is constituted by integrally forming left and right down frame sections and upper and lower cross member sections, which connect the left and right down frame sections each other, with mold forging.

7. A body frame for a motorcycle according to claim 4 or 6, characterized in that the head pipe unit comprises an aluminum die-cast molded product or an aluminum forged molded product constituted by setting a direction for die cutting of a mold to a vehicle width direction.

8. A body frame for a motorcycle according to any one of claims 4, 6, and 7, characterized in that dimensions in a vehicle width direction and a height direction of the lower main frame section are set larger than dimensions in a vehicle width direction and a height direction of the upper main frame section.

9. A body frame for a motorcycle according to any one of claims 4 and 6 to 8, characterized in that vehicle-mounted components or body components are attached to a recessed portion formed by the upper and lower main frame sections and the gusset sections.

10. A body frame for a motorcycle according to any one of claims 4 and 6 to 9, characterized in that through-holes for passing an operation cable or electric wiring from one side to the other side in the vehicle width direction are formed in the gusset sections.

11. A body frame for a motorcycle according to any one of claims 4, 6, and 7 to 10, characterized in that an engine suspending bracket section is integrally formed with the gusset sections.

6. A body frame for a motorcycle, characterized by comprising a head pipe unit generally I-shaped in a cross section thereof which is constituted by integrally forming an upper main frame section with a rectangular shape in a section thereof extending obliquely downward to the rear of the vehicle from the upper end of the head pipe, a lower main frame section with a rectangular shape in a section thereof extending downward to the rear of the vehicle from the lower end of the head pipe, and gusset sections of a vertical wall shape which closes a space surrounded by the head pipe and the upper and lower main frame sections and whose vehicle width dimension is set smaller than a vehicle width dimension of the respective main frame sections.

12. A body frame for a motorcycle comprising:

a head pipe unit constituted by joining a frame member to a head pipe;

a down frame extending downward to a rear of a vehicle from a front part at lower end of the head pipe unit; and

rear arm brackets connecting the down frame and a rear part at lower end of the head pipe unit, characterized in that the down frame is constituted by integrally forming left and right down frame sections and upper and lower cross member sections, which connect the left and right down frame sections each other, with mold forging.

13. A body frame for a motorcycle according to claim 5 or 12, characterized in that the lower cross member section connects rear ends of the left and right down frame sections each other, and a pair of left and right link bracket sections supporting a rear wheel suspending device are integrally formed in the cross member section so as to protrude to the rear of the vehicle.

14. A body frame for a motorcycle according to any one of claims 5, 12, and 13, characterized in that a maintenance opening for change pedal opening in a vertical direction is formed in a connecting portion of rear ends of the left and right down frame sections and the lower cross member section or in a connecting portion of the rear ends, the lower cross member section, and lower ends of the rear arm brackets.

15. A body frame for a motorcycle according to any one of claims 5 and 12 to 14, characterized in that an engine bracket section is integrally formed with the left and right down frame sections.

16. A body frame for a motorcycle according to any one of claims 5 and 12 to 15, characterized in that the left and right down frame sections have a sectional shape of a generally downward C shape and are formed such that a lower surface of a vertical wall on an outer side of the vehicle is placed higher than a lower surface of a vertical wall on an inner side of the vehicle.

17. A body frame for a motorcycle according to claim 16, characterized in that a cover is disposed in a recessed portion opening downward of the left and right down frame sections so as to cover the recessed portion or foaming resin is filled in the recessed portion.