JP3106723B2 - Exhaust pipe structure of motorcycle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust pipe structure, and more particularly to an exhaust pipe structure suitable for a motorcycle.

[0002]

2. Description of the Related Art Exhaust gas guided from each cylinder of an engine is exhausted through an exhaust pipe as an exhaust pipe. As shown in FIG. 4, one end 41a of the exhaust pipe 41 is connected to an engine (not shown), and the other end 41b is connected to a muffler (not shown).
In FIG. 6, 45 indicates a front wheel, 46 indicates a frame, and 47 indicates a front fender. The normal positions of the front wheel and the front fender are 45a, 4
7a, the position of the front fork at the maximum pressure is 45
b and 47b.

[0003]

Incidentally, the diameter of the exhaust pipe 41 has a great influence on the performance, and therefore, an optimized design has been made. In this design stage, the radiator 42, the front wheels 45, and the like are laid out with the exhaust pipe 41 and the engine as close as possible to shorten the wheelbase and reduce the weight of the vehicle body. Therefore, it is difficult to change the diameter of the exhaust pipe 41 once it is determined from the clearance with other parts.

However, in testing during development,
In some cases, it is necessary to increase the diameter of the exhaust pipe 41, and in such a case, there is a problem that it is difficult to secure a clearance between the radiator 42 and the exhaust pipe 41. Young radiator 42
If the vehicle is to be moved to the front wheel 45 side, the front wheel 45 must also be moved forward, and the wheelbase is extended, resulting in a significant change in the vehicle body layout.

When it is desired to increase the diameter of the exhaust pipe 41, the clearance between the radiator 42 and the exhaust pipe 41 must be secured as shown in FIG.
As shown in (2), there is a case where the corresponding portion ARa of the radiator 42 of the exhaust pipe 41 is dented to reduce the cross-sectional area. However, when the cross-sectional area of the exhaust pipe 41 is reduced in this way, there is a problem that the engine output is reduced and the performance is reduced.

In order to secure a clearance without reducing the cross-sectional area of the exhaust pipe 41, that is, without lowering the performance, as shown in FIG. 6, a member 49a having an extremely small radius of curvature is provided. One end 41a of the exhaust pipe 41 is also formed by press-forming the 49b and joining the members 49a and 49b by, for example, welding. Or, FIG.
As shown in FIG. 2, members 48a and 48b having irregular cross sections are formed by pressing, and the corresponding portions ARa are formed by joining the members 48a and 48b. However, in these cases, there is a problem that the cost of the press die is increased and the welding must be performed, which increases the cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is possible to minimize the change of the vehicle body layout and use a thick exhaust pipe, in other words, to increase the output of the engine. It is an object to provide a motorcycle exhaust pipe structure that can be made high.

[0008]

According to the present invention, a radiator and an engine are mounted on a frame, the radiator is disposed in front of the frame, and a front wheel and a front fender are disposed in front of the radiator. A motorcycle in which a fender is disposed at a position where the fender does not interfere with the radiator when the front fork is at its maximum pressure, wherein an exhaust pipe is connected to each cylinder of the engine, and the exhaust pipe is disposed between the radiator and a frame. In the exhaust pipe structure of a motorcycle, an engine-side connecting member having a smaller diameter and a smaller radius of curvature than the exhaust pipe is provided between the engine and the exhaust pipe. An exhaust pipe structure of a motorcycle.

[0009]

[Function] The pipe provided between the engine and the exhaust pipe has a smaller diameter and a smaller radius of curvature than the exhaust pipe.
In addition, a thicker exhaust pipe can be used in a state where the clearance between the radiator and the engine is secured, and further improvement in engine output and performance can be realized.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In the configuration of FIG. 1, exhaust gas guided from each cylinder of the engine (not shown) is discharged to the exhaust pipe 1 via the engine-side connecting member 11.
The engine side 1f of the exhaust pipe 1 is connected to an engine (not shown) via an engine side connecting member 11, and the other end 1b is connected to a muffler (not shown).

In FIG. 1, 2 is a radiator, 5a, 5b
Denotes a front wheel, 6 denotes a frame, and 7a and 7b denote front fenders. The normal positions of the front wheel 5 and the front fender 7 are indicated by 5a and 7a, respectively, and the positions of the front fork at the maximum pressure are indicated by 5b and 7b.

As the engine-side connecting member 11, a pipe having a smaller diameter than the exhaust pipe 1 and having a minimum radius of curvature that can be processed is used. The connection state of the engine side connection member 11 and the exhaust pipe 1 is shown in FIG.
Is shown in In FIG. 2, the engine side connecting member 1
A state in which the exhaust pipe 1 is connected to the exhaust pipe 1 is indicated by a solid line, and a state in which the exhaust pipe 1 is directly connected to the engine is indicated by a chain line.

Referring to FIG. 2, an example of the diameter size and the radius of curvature of the engine side connection member 11 will be described. The diameter size of the engine side connection member 11 is 35 mm, and the radius of curvature is 70 mm. On the other hand, the diameter of the exhaust pipe 1 is 38.1 mm, and the radius of curvature is 80 mm. And one end side 11a of the engine side connection member 11
Is connected to the engine.

In FIG. 2, the exhaust pipe 1 is connected to the engine via an engine-side connecting member 11 which has a smaller diameter than the exhaust pipe 1 and has a minimum radius of curvature which can be machined, as shown by a solid line. Radiator 2
Interference with the exhaust pipe 1 is eliminated and clearance can be secured. Accordingly, it is possible to use a thicker exhaust pipe 1 correspondingly, and it is possible to improve the engine output and the performance.

FIG. 3 shows a state in which the engine output is improved. In FIG. 3, the solid line La indicates the engine-side connecting member 1.
1, the relationship between the engine speed and the output when the exhaust pipe 1 is thickened is shown. In FIG. 3, a broken line Lb shows the relationship between the engine speed and the output in the prior art. ing. As is apparent from FIG. 3, the use of the engine-side connecting member 11 allows the use of the thicker exhaust pipe 1 while ensuring the clearance between the radiator 2 and the exhaust pipe 1, thereby further improving the engine output. Becomes possible.

The exhaust gas from each cylinder of the engine is
Engine-side connecting member 11 and exhaust pipe 1
And is discharged to a muffler (not shown) after being merged at the merging portion 1e of the exhaust pipe 1 through the pipe.

In this embodiment, the exhaust pipe 1
The engine side portion 1f of the exhaust pipe 1 is connected to the engine via an engine side connection member 11 which is a pipe having a smaller diameter and a minimum radius of curvature that can be machined.

Therefore, the interference between the radiator 2 and the exhaust pipe 1 can be eliminated while minimizing the change in the vehicle body layout. In addition, it is possible to use a thicker exhaust pipe 1 while securing a clearance between the radiator 2, the exhaust pipe 1 and the engine-side connecting member 11. As a result, the engine output and the performance can be further improved. Also, the engine side connection member 1
As 1, a pipe can be used, and a step such as press molding or welding is not required, and the cost does not increase.

[0019]

According to the present invention, the interference between the radiator and the exhaust pipe can be eliminated while minimizing the change of the vehicle body layout. Further, a thicker exhaust pipe can be used while securing clearance between the radiator and the exhaust pipe and the pipe. Further, it is possible to further improve the engine output and the performance. Further, when the pipe is provided, steps such as press molding and welding are not required, and there is an effect that the cost is not increased.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a connection state between an exhaust pipe and an engine-side connection member.

FIG. 3 is a diagram showing a relationship between an output of an engine and a rotation speed.

FIG. 4 is a view showing an exhaust pipe according to the related art.

FIG. 5 is an explanatory diagram showing an example of a conventional technique.

FIG. 6 is an explanatory diagram showing another example of the related art.

FIG. 7 is an explanatory diagram showing still another example of the related art.

FIG. 8 is a partially enlarged cross-sectional view taken along line Xa-Xa in FIG.

[Explanation of symbols]

 1, 41 exhaust pipe 11 engine side connection member 48, 48a, 48b member 49, 49a, 49b member

Claims (1)

(57) [Claims] 1. A radiator and an engine are mounted on a frame, the radiator is disposed in front of the frame, and a front wheel and a front fender are disposed in front of the radiator. An exhaust pipe structure for a motorcycle, wherein the exhaust pipe is connected to each cylinder of the engine, and the exhaust pipe is disposed between the radiator and a frame. An exhaust pipe structure for a motorcycle, wherein an engine-side connecting member having a smaller diameter and a smaller radius of curvature than the exhaust pipe is provided between the engine and the exhaust pipe.