JPS604477A - Car body frame for motorcycle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle body frame having a pivot connection portion for a rear wheel suspension cushion unit near the longitudinal center of the vehicle body frame, that is, near the output shaft of an engine.

Recently, in order to improve the lateral rigidity of the vehicle body frame and to increase the cushion stroke of the cushion unit, and to improve ride comfort, a cushion unit for rear wheel suspension has been installed in the longitudinal center of the vehicle body frame, that is, near the output shaft of the engine. A single-shock type rear wheel suspension system is often used in which the upper end of the unit is pivoted and a swing arm supporting the rear wheel is connected to the lower end of the unit. By the way, in the conventional body frame of such a motorcycle, for example, as shown in FIG.
A pivot connecting portion 09' of the rear wheel suspension cushion unit C' is formed on the bracket B'.

By the way, since a large load from the rear wheel acts on the pivot connection part 09' through the cushion unit C', the connection part 09' needs to have rigidity to withstand the large load. The pivot connection 09' does not require any rigidity, since the load acting on the connection 08'a of the seat rail 08' is relatively small compared to the pivot connection 09'. However, in the conventional vehicle body frame, the bracket B' is integrally formed of a plate material of uniform thickness.
The entire pivot connection part 09, which bears the heaviest load,
As a result, the connecting portion 08'a of the seat rail 08' has more rigidity than necessary, resulting in an increase in the weight of the vehicle body frame.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a body frame for a motorcycle with a simple structure that contributes to reducing the weight of the body frame without impairing its rigidity. It is.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

On the back surface of a head pipe 1 that supports a front fork (not shown) in a steerable manner in FIGS. 1 to 4.

Below, the front end of the main pipe 2 and the front end of the down tube 3 are welded together, and their joint is reinforced by a gusset 4. The main pipe 2 extends rearward, and a bracket B, which will be described in detail later, is welded to the rear end. Further, the down tube 3 is curved into a substantially U-shape when viewed from the side, and the lower ends of the lower pipe 5 and the back stay 6 are integrally welded to the rear end thereof. Also, between the middle of down tube 3 and the rear end of main pipe 2,
Both ends of the reinforcing pipe 70 are welded together.

The front end of a seat rail 8 on which a seat (not shown) is placed is welded to the rear part of the bracket B, and the upper end of the lower pipe 5 is welded to the lower part of the bracket B. Further, the upper end of a rear wheel suspension cushion unit C is pivotally connected to the rear end of the bracket B, as shown by the chain line in FIG. be done.

Next, the specific structure of the bracket B will be explained mainly with reference to FIGS. 2 to 4.

The bracket B has a front half part 11 made of a relatively thin plate material, and a rear part made of a thicker plate material than the first half part 11, which is integrally welded to the rear part of the first half part 11. It consists of part 12.

An insertion receiving part 13 that is open to the front is formed above the front part of the first half part 11, and the rear end of the main pipe 2 is inserted into this insertion receiving part 13, and a reinforcing pipe I is welded thereto.
It is inserted together with the rear end and welded together there. Further, the upper ends of the left and right lower pipes 5 are welded to both sides of the lower portion of the front half portion 11, which has a U-shaped longitudinal section.

The latter half 12 of the bracket B is made of a thicker plate material than the first half 11 and has an inverted U-shape in cross section, and is welded to the rear upper part of the first half 11 so as to straddle it. be done.

Further, a bearing sleeve 14 is horizontally suspended and welded to the rear portion of this front half portion 11, and the front end of the seat rail 8 is connected thereto by a connecting hole 5. On the other hand, the pivot connecting portion 9 of the cushion unit C is formed in the rear half portion 12 .

6 - Since the latter half part 12 is formed of a thicker plate material than the first half part 11, it has higher rigidity than the first half part 11.

By the way, when a motorcycle is running, the rear wheel W receives a large impact from the road surface, especially the uneven road surface.

Vibration is transmitted from the rear wheel W to the pivot connection part 9 of the bracket B via the swing arm 10 and the cushion unit C, and a large load is applied thereto. Since it is provided in the rear half portion 12, it has enough strength to withstand large shocks and vibrations.

On the other hand, since the load applied to the connection part 8a of the seat rail 8 of the bracket B is smaller than the load applied to the pivot connection part 9, the connection part f3a may be provided in the front half part 11 which is thinner than the rear part 12. , the front half portion 11 has sufficient strength to withstand the load from the seat rail 8.

In addition, the front half 11 and rear half 12 of the bracket B mutually reinforce each other, so that high rigidity can be obtained as a whole.

As described above, according to the present invention, the bracket is coupled to the rear end of the main pipe extending rearward from the head pipe,
In a vehicle body frame in which the front end of the seat rail on which the seat is mounted is connected to this bracket, and the pivot connection part of the rear wheel suspension cushion unit is provided, the pivot connection part of the bracket is formed thicker than other parts. Therefore, it is possible to locally increase the rigidity of the pivot connection part, which is subjected to the heaviest load, in the bracket, and the thickness of the entire bracket is increased to correspond to the pivot connection part, which is subjected to the heaviest load, unlike in the past. There is no need to form a bracket, which makes it possible to significantly reduce the weight of the bracket, which contributes to reducing the weight of the vehicle frame as a whole without any loss in strength.

[Brief explanation of the drawing]

Figures 1 to 4 show an embodiment of the vehicle body frame of the present invention. Figure 1 is an overall side view thereof, Figure 2 is an enlarged plan view of Figure 1, and Figure 3 is a diagram of Figures 2 - ■. 4 is a sectional view taken along the line ■--■ in FIG. 2, and FIG. 5 is a partial side view of a conventional vehicle body frame. C... Cushion unit, B... Bracket, 1
...Head pipe, 8...Seat rail, 9...
Patent application for pivot connection part Person Honda Motor Co., Ltd. -9=

Claims (1)

[Claims] A bracket is connected to the rear end of the main pipe that extends rearward from the head pipe, and this bracket is connected to the front end of the seat rail on which the seat is mounted, as well as a pivot connection part for the rear wheel suspension cushion unit. A body frame for a two-wheeled motor vehicle, characterized in that a pivot connecting portion of the cushion unit of the bracket is formed thicker than other parts.