JPH043919Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention provides a main lower pipe that splits into two toward the rear at the rear end of the down tube, and a support that supports the rear wheel shock absorbing mechanism. The present invention relates to a frame structure of a two-wheeled motor vehicle in which the rear end of the main lower pipe is connected to a cross pipe from which a bracket is projected.

(Prior Art) As shown in FIG. 4, the frame structure generally formed in a motorcycle is such that the front ends of a main tube 2 and a down tube 3 are connected to a head pipe 1, and the rear end of the main tube 2 is connected to a head pipe 1. Sub-pipes 4, 4 which are divided into two branches are extended.

The lower end portions of the sub pipes 4, 4 are connected to a cross pipe 5 facing in the width direction of the vehicle body, while the rear end portions of the main lower pipes 13, 13 are bifurcated rearward from the rear end portion of the down tube 3. The end is connected to the cross pipe 5 mentioned above.

In this case, a support bracket 6 is projected from the cross pipe 5 in the middle thereof in the axial direction, and a support bracket 6, for example,
It connects and supports one end of the rear wheel shock absorbing mechanism disclosed in Japanese Patent Laid-Open No. 53-2839.

Here, although the shock absorber is provided with a shock absorber, the force generated during shock absorption is considerable and is applied to the support bracket 6, and the force is applied to the middle of the cross pipe 5. act.

However, in the conventional frame structure, as shown in FIG. 4, the rear end of the down tube 3 and the cross pipe 5 are connected only by a pair of left and right main lower pipes 13, 13.

For this reason, the cross pipe 5 is only supported at both ends of its axis, and therefore receives a bending moment. Therefore, as the cross pipe 5, a large diameter pipe or a thick wall It was necessary to use thick pipes. In addition, since the down tube 3 and the cross pipe 5 are connected only by the main lower pipes 13, 13, there are only two main lower pipes 13, 13,
13 lacks strength, and for this reason, it was necessary to use large diameter pipes or thick walled pipes as the main lower pipes 13, 13.

(Purpose of the invention) This invention was made in view of the above-mentioned problems, and aims to make the cross pipe and the main lower pipe lightweight and inexpensive.

(Structure of the device) In order to achieve the above object, this device extends the rear end of the down tube to the rear and connects it to the cross pipe, and connects the down tube and the support bracket to the cross pipe. By arranging the down tubes so as to correspond approximately to the middle in the axial direction, bending of the cross pipe is prevented by the down tube.

(Example) Hereinafter, an example of this invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing the body frame of a motorcycle. In the figure, 1 is a head pipe located at the front end of the frame. A down tube 3 is connected to the down tube 3. The main tube 2 is made of one square pipe, and at its rear end there is a pair of sub-pipes 4 divided into left and right sides.
4 is fixed so as to spread backward.

A cylindrical cross pipe 5 is connected between the lower ends of these sub pipes 4,4.

As shown in FIG. 2, the cross pipe 5 has a cylindrical ring located approximately in the middle in its axial direction (vehicle width direction).
Support bracket 6 protruding rearward and diagonally upward
is fixed to this support bracket 6,
One end of the bell crank 7 on the base side is connected.

The bell crank 7 has one end on its distal end side connected to the other end of a shock absorber 8. The upper end of the shock absorber 8 in this case is supported by a mounting bracket 9 protruding from the rear end of the main tube 2.

Further, the front and rear of the bell crank 7 and a swing arm 10 having a rear wheel (not shown) at its rear end are connected by an interlocking link 11. The swing arm 10 in this case is connected to an arm bracket 12 protruding from the sub pipe 4.

Here, a rear wheel shock absorbing mechanism S is composed of the shock absorber 8, the bell crank 7, the interlocking link 11, and the like.

On the other hand, the down tube 3 is formed of a square pipe, and is formed by bending one pipe, thereby providing a front portion 3A and a rear portion 3B.

The rear portion 3B corresponds to a rearwardly extending portion when viewed from the conventional structure shown in FIG.
The rear end portion of B is fixed to correspond to the middle of the cross pipe 5 in the axial direction (vehicle width direction). In this case, the rear portion 3B of the downtube 3 is disposed in substantially corresponding relation to the front side of the support bracket 6, as shown in FIG.

The front end of the rear 3B of such down tube 3,
A pair of main lower pipes 13, 13 are fixed between the cross pipe 5 and the main lower pipes 13, which extend rearward in a bifurcated shape.

In addition, 14 in FIG. 2 is a first engine mount bracket that protrudes from the front portion 3A of the down tube 3, and 15 is a second engine mount bracket that protrudes from each of the main lower pipes 13, 13. . Furthermore, the arm bracket 12 is also used as another engine mount bracket.

Further, 16 is a rear pipe, which consists of an upper rear pipe 16A and a lower rear pipe 16B. Furthermore, 17 is a side bracket that connects the lower end of the sub pipe 4 and the cross pipe 5 by covering them from the outside, and using the outer side of each of these side brackets 17, a step (not shown) is carried out. A step mounting bracket 18 for mounting is protruding.

In the above configuration, the down tube 3 extends rearward as shown in FIG. 1, its rear end is connected to the cross pipe 5, and the connection point is connected to the support bracket 6
are arranged accordingly. Here, as shown in FIG. 2, a load acts on the swing arm 10 counterclockwise in the direction of arrow U, and the interlocking link
While the bell crank 7 is rotated in the same direction through the shock absorber 8, a downward force in the direction of arrow D acts on the support bracket 6 as a reaction force from the shock absorber 8, so that a tensile force in the direction of arrow P is applied to the support bracket 6. act.

In this case, the tensile force P causes the support bracket 6 to
Even if the cross pipe 5 tries to undergo a bending action through the cross pipe 5, the tensile force P is supported by the down tube 3 because the rear part 3B of the down tube 3 is connected to the front side of the cross pipe 5 as shown in FIG. Therefore, the cross pipe 5 is not subjected to bending action. As a result, the cross pipe 5 is thin, and
It becomes possible to use a pipe with a thin wall thickness, and since the main lower pipe 13 mainly provides resistance from the down tube 3 with a large diameter in the center, it is possible to use a pipe with a thin wall thickness, and the main lower pipe 13 is thin enough to support the engine. This makes it possible to use thinner pipes.

As a result, the weight and cost of the cross pipe 5 and the main lower pipe 13 can be reduced.

In the above embodiment, from the perspective of the mechanism shown in FIG. 2, only the tensile force P, not the compressive force, acts on the down tube 3, but the down tube 3 has a strong property against tension. , which is advantageous in terms of strength and allows the use of thinner pipes.

(Effects of the invention) As explained above, according to this invention, the rear end of the down tube is connected to the cross pipe, and the down tube and the support bracket are connected to each other at approximately the center in the axial direction of the cross pipe. Since the cross pipes are arranged in a corresponding relationship, bending of the cross pipe can be prevented by the down tube, and therefore the cross pipe and the main lower pipe can be made of lightweight and low cost materials.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a frame structure showing an embodiment of this invention, Fig. 2 is a left side view thereof, Fig. 3 is a sectional view taken along the - line in Fig. 2, and Fig. 4 shows a conventional frame structure. FIG. 3...Down tube, 5...Cross pipe,
6... Support bracket, 13... Main lower pipe, S... Rear wheel shock absorbing mechanism.

Claims (1)

[Scope of utility model registration request] At the rear end of the down tube, there is a main lower pipe that splits into two toward the rear, and
In a motorcycle frame structure in which a rear end of the main lower pipe is connected to a cross pipe from which a support bracket for supporting a rear wheel shock absorbing mechanism is protruded, the rear end of the down tube is extended rearward. A frame structure for a two-wheeled motor vehicle, characterized in that the frame structure is connected to a cross pipe, and the down tube and the support bracket are arranged in a relationship corresponding to approximately the middle in the axial direction of the cross pipe.