JPH0144399Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an exhaust system for a motorcycle equipped with a V-type engine, and particularly to the arrangement of an exhaust pipe and a muffler connected to the rear cylinder of the engine.

The pressure waves generated in the engine's exhaust pipe are reflected at the end of the exhaust pipe and reach the inside of the cylinder, so engine performance is affected in a complex manner by the amplitude and frequency of the waves, so there is an optimal length for the exhaust pipe. do. Particularly in a multi-cylinder engine, it is necessary to set the equivalent pipe length of each exhaust pipe to be equal.

By the way, when the engine mounted on a motorcycle is a V-type engine, consideration is required to set the equivalent pipe lengths of both the exhaust pipe extending from the front cylinder and the exhaust pipe extending from the rear cylinder to be equal. .

This idea was created in view of these circumstances,
The purpose of this is to install the first exhaust pipe extending from the rear cylinder of the engine near the rear fork pivot point of the vehicle body in a roughly U-shape on the side, and also to install the first exhaust pipe extending rearward from the front cylinder of the engine. A second exhaust pipe is installed substantially horizontally with respect to the vehicle body, and the first and second exhaust pipes are connected to a muffler that extends rearward from near the pivot point and is supported by the frame at the rear thereof. Accordingly, there is provided an exhaust system for a motorcycle in which the equivalent pipe length of the first exhaust pipe connected to the rear cylinder can be set equal to that of the second exhaust pipe connected to the front cylinder.

A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an overall side view of a motorcycle having an exhaust system according to the present invention, FIG. 2 is a side view of a body frame of the motorcycle, and FIG. 3 is an exploded perspective view of the exhaust system.

A head pipe 3 is fixed to the front end of the body frame 2 of the motorcycle 1 shown in FIG. 1. A stem shaft is rotatably inserted into the head pipe 3, and a handle 4 is provided at the upper end of the stem shaft as shown in the figure. It is permanently installed. Further, the upper end of a front fork 7 is fixed to the stem shaft via both top and bottom bridges 5 and 6, and a front wheel 8 forming a steering wheel is rotatably supported at the lower end of the front fork 7.

On the other hand, a fuel tank 9 and a seat 10 are arranged behind the head pipe 3, and below the fuel tank 9 are a front cylinder 11a and a rear cylinder 11.
A V-type engine 11 having a V-shape is mounted. The fuel tank 9 has a substantially U-shape in plan as shown in FIG. 4, and the front blinker 51 is positioned above the tank 9 when the handle 4 is tightened.

Further, the front end of a rear fork 12 is pivotally attached to the bent base of the down pipe lower 2a constituting the vehicle body frame 2 by a pivot shaft 13 so as to be able to swing vertically. A ring 14 is rotatably supported. Note that this rear fork 12 is suspended on the vehicle body side via a link mechanism (not shown).

FIG. 2 shows details of the vehicle body frame 2. In the figure, reference numeral 15 denotes a main pipe having the head pipe 3 fixed to its front end.
A down pipe 16 hangs down from the front lower part of the tank, and the down pipe 16 is made of a thick pipe and also serves as an oil tank. Note that 17 in the figure is an oil pipe.

The down pipe lower 18 made of a thin pipe extends rearward from the lower end of the down pipe 16, the rear end of which is bent upward as shown in the figure, and the pivot shaft 13 is attached to the bent end.
A bracket 19 for inserting and supporting is connected. A center pipe 20 is arranged above the bracket 19, and the center pipe 20 is arranged above the bracket 19.
The upper end of the main pipe 15 is connected to the rear end of the main pipe 15.

The engine 11 is mounted on the vehicle body frame 2 by supporting its transmission case 11c on support brackets 16a, 18a, 20a projecting from each of the pipes 16, 18, 20.

On the other hand, a seat rail 21 extends rearward from the upper part of the center pipe 20, and from a position below the seat rail 21 and above the bracket 19, a rear stay 22 tilts upward toward the rear and is fixed. It is set up.

The down pipe 16, lower down pipe 18, center pipe 20, seat rail 21, and rear stay 22 are all made of square pipes.

By the way, the front cylinder 1 of the engine 11
From the front side of 1a, there is an exhaust pipe 23 which is a second exhaust pipe.
The exhaust pipe 23 is bent and extended rearward, and the exhaust pipe 23 is installed substantially horizontally with respect to the vehicle body. A muffler 24 is connected to the rear end of the exhaust pipe 23, and the muffler 24 is arranged so as to face rearward and tilt upward along the rear stay 22.
The rear part of this is supported by the rear part of the rear stay via a bracket 24a provided thereon and a bracket 22a protruding from the rear stay 22. Furthermore, exhaust pipe 2
3 and the muffler 24 are installed on the left side facing the front of the vehicle body.

On the other hand, from the rear side of the rear cylinder 11b, the other first exhaust pipe 25 extends obliquely downward to the right side and toward the front of the vehicle body, opposite to the exhaust pipe 23. It is bent into a roughly U-shape as shown in the diagram, surrounding the
The front part is supported by a bracket 31 protruding from the transmission case 11c, and a muffler 26 is connected to the rear end of the bracket 31. And this muffler 2
6 is arranged along the rear stay 22 similarly to the muffler 24, and the rear part of this is supported by the rear stay 22. Note that the U-shaped portion 25a of the exhaust pipe 25
are connected by occluded bands 32 and 33.

The base of the bracket 31 is connected to the transmission case 11c with a screw 34, and the front part 25 of the exhaust pipe 35 is connected to the transmission case 11c with a screw 34.
b is fastened and supported by a screw 35 at the occluded band portion. The front portion 25b of the exhaust pipe 25 is connected to a cylinder head which is detachable from the rear cylinder 11b with screws 36, 36.

As shown in FIG. 5, the inside of the main pipe 15 constitutes an air cleaner chamber S, and a patch 41 is interposed between the main pipe 15 and the center pipe 20 connected to the left and right side surfaces of the rear end of the main pipe 15. is first welded to the side surface of the main pipe 15, and later the center pipe 20 is welded to the patch 41 to connect both pipes 15 and 20. By employing such a patch 41, the influence on the air cleaner chamber S caused by the welded joint can be prevented.

In the above, it is necessary to set the equivalent pipe lengths of both exhaust pipes 23 and 25 to be equal, but the cylinder 11
Due to the fact that a and 11b are installed in a V-shaped side,
If no consideration is given to the installation of the exhaust pipe, the exhaust pipe 23 connected to the front cylinder 11a will inevitably be longer than the exhaust pipe 25 connected to the rear cylinder 11b.

However, in this embodiment, the front cylinder 11a
The exhaust pipe 23 connected to the rear cylinder 11b is installed approximately horizontally to the vehicle body, and the exhaust pipe 25 connected to the rear cylinder 11b is installed in a U-shape so as to surround the pivot shaft 13, so as to increase the length of the exhaust pipe. Therefore, the equivalent pipe lengths of both exhaust pipes 23 and 25 can be set to be equal.

Also, move both mufflers 24 and 26 to pivot shaft 1.
Since it is installed along the rear stay 22 which is fixedly installed at a position above 3 and tilted upward toward the rear, rational installation is possible especially for motorcycles where installation space is limited.

As is clear from the above explanation, according to the present invention, the first exhaust pipe extending from the rear cylinder of the engine is installed near the rear fork pivot point of the vehicle body in a substantially U-shape on the side, and A second exhaust pipe extending rearward from the cylinder is installed approximately horizontally with respect to the vehicle body, and the first and second exhaust pipes extend rearward from near the pivot point and are supported by the frame at their rear portions. By connecting to the muffler, the equivalent pipe length of the first exhaust pipe connected to the rear cylinder can be set equal to that of the second exhaust pipe connected to the front cylinder.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is an overall side view of a motorcycle, Fig. 2 is a side view of the body frame of the motorcycle, and Fig. 3 is an exploded perspective view of an exhaust system. Figure 4 is a plan view of the fuel tank.
FIG. 5 is a sectional view taken along the line 5--5 in FIG. In the drawings, 1 is a motorcycle, 2 is a body frame, 3 is a head pipe, 11 is a V-type engine, 1
1a is the front cylinder, 11b is the rear cylinder, 1
3 is the pivot shaft, 15 is the main pipe, 1
6 is down pipe, 18 is down pipe lower, 2
0 is the center pipe, 21 is the seat rail, 22
is rear star, 23, 25 are exhaust pipes, 24, 26
is the exhaust muffler.

Claims (1)

[Scope of utility model registration request] This is an exhaust system for a motorcycle equipped with a V-type engine, in which a first exhaust pipe extending from the rear cylinder of the engine is installed near the rear fork pivot point of the vehicle body in a substantially U-shape on the side. A second exhaust pipe extending rearward from the front cylinder is installed approximately horizontally with respect to the vehicle body, and the first and second exhaust pipes extend rearward from near the pivot point and are supported on the frame side at the rear part thereof. An exhaust system for a motorcycle, characterized in that it is connected to a muffler.