JPS6329083B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust system for a motorcycle. More specifically, the present invention relates to an improved exhaust system for a motorcycle equipped with a multi-cylinder engine.

Conventionally, in motorcycles equipped with multi-cylinder engines, multiple exhaust pipes extending from each cylinder are centrally connected to a large-capacity shell-structured muffling chamber, and this muffling chamber is communicated with the atmosphere through multiple muffling pipes. There is something like this. This type of exhaust system has a large-capacity silencing chamber, which improves the silencing effect, and multiple exhaust pipes are centrally connected to the silencing chamber, resulting in a suction effect (hereinafter simply referred to as pulsating effect) caused by exhaust pulsating waves. By mutually affecting each cylinder, it is possible to further improve the output.

However, the above-mentioned pulsation effect changes as the valve overlap time changes depending on the engine speed, and depending on a certain engine speed, the exhaust gas coming out of one exhaust pipe may flow into the other exhaust pipe. In some cases, the pulsation effect entered the cylinder and flowed back into the cylinder, thereby reducing the original output improvement effect due to the pulsation effect.

In addition, the noise reduction effect of the above-mentioned shell-structured sound-muffling chamber increases as the internal volume increases, but this increases the flat surface area of the wall surface, resulting in a decrease in rigidity and the problem of generation of shell noise due to vibration. It was hot.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust system for a motorcycle that eliminates the above-mentioned problems and reduces the generation of screeching noise without reducing the output improvement achieved by utilizing the pulsation effect.

To achieve the above object, the present invention includes an exhaust system in which a plurality of exhaust pipes extending from each cylinder of a multi-cylinder engine are connected to a muffling chamber made of a hollow shell structure, and a plurality of muffling pipes are further connected to the muffling chamber. In the motorcycle, the inside of the muffling chamber is partitioned into left and right chambers by a partition plate in the front and rear direction, and a communication hole is provided in the partition plate to communicate the left and right chambers, and the hole extends from each cylinder to a front wall side of each chamber. The exhaust pipe is characterized in that a plurality of exhaust pipes are divided into two parts, each having a connecting opening, and the muffling pipe is connected to the rear wall side of each chamber.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Details will be explained below with reference to embodiments of the present invention shown in the drawings.

FIG. 1 is a diagram showing an exhaust system for a motorcycle equipped with a four-cylinder engine according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 indicates four exhaust pipes extending from four cylinders, respectively. These four exhaust pipes 1, 1, 1, 1 are divided into two parts each and connected to the front wall of one muffling chamber 2. As will be described later, the interior of the silencing chamber 2 is divided into two left and right chambers by a partition plate 5 in the front and rear directions, and the two exhaust pipes 1, 1 and 1, 1 are connected to each of these chambers. . Further, muffling pipes 3, 3 are connected to the rear wall side of each of the left and right halves of the chamber, respectively, and are provided so as to extend along the side portions of the vehicle body. Reference numeral 2a denotes an attachment part fixed to the rear part of the muffling chamber 2, and 3a denotes an attachment part fixed to the muffler pipe 3, which are adapted to be attached to the vehicle body via the attachment parts 2a and 3a.

As shown in FIGS. 2 and 3, the silencing chamber 2 is constructed so that its outer periphery is surrounded by a sealed shell 4, and a partition plate 5 is provided by spot welding or the like in the front-rear direction approximately at the center of the shell 4. It is fixedly installed and divides the inside of the sound deadening chamber 2 into left and right. The partition plate 5 is provided with a communication hole 5a that communicates the left and right sides, and
A convex portion 5b is provided so as to protrude from one side surface to the other side surface. The convex portion 5b is provided to increase the rigidity of the partition plate 5, and may have any shape other than the cross shape shown in the figure. Reference numeral 6 denotes a wire mesh fixed to the inner wall surface of the shell 4, which increases the rigidity of the shell 4 and also increases the sound-damping effect by sound absorption. Reference numeral 7 denotes a protective cover fixed to cover the outside of the muffling chamber 2 and muffling tube 3 with a space therebetween, and is intended to protect the driver from the heated muffling chamber 2 and muffling tube 3.

In the device described above, four exhaust pipes 1, 1,
Exhaust gas alternately exhausted from 1 and 1 is transferred to silencing chamber 2.
The silencing chamber 2 is fed with a partition plate 5 that is fixed to the shell 4 of the silencing chamber 2, which increases the rigidity of the silencing chamber itself. does not vibrate significantly due to fluctuations in exhaust pressure, and therefore the shell noise is reduced.

In addition, the exhaust pipes 1, 1 are divided into two parts each;
The exhaust gases 1 and 1 are respectively discharged into the left and right chambers of the muffling chamber 2, expanded and muffled, and further muffled by the muffling pipe 3 connected to each chamber, before being discharged into the atmosphere. When exhaust gas is discharged from the exhaust pipe 1 to each chamber of the silencing chamber 2 in this way, the pulsating waves of the exhaust gas freely enter the chamber on the opposite side through the communication hole 5a of the partition plate 5, so that the pulsating waves of the exhaust gas are connected to that chamber. By reaching other exhaust pipes 1, a pulsating effect is produced, but on the other hand, the amount of the exhaust itself entering is limited by the flow resistance of the communication hole 5a. Therefore, the exhaust gas is less likely to flow back into the exhaust pipe 1 of the opposite chamber, so that the output improvement effect by utilizing the pulsation effect is not inhibited.

As described above, the exhaust system for a motorcycle according to the present invention divides the interior of the shell-structured noise reduction chamber into left and right chambers by a partition plate in the front and rear direction, and a communication hole is provided in the partition plate to communicate the left and right chambers. Since the chamber is configured to have a plurality of exhaust pipes extending from each cylinder of a multi-cylinder engine divided into two and each connected to the opening, the amount of exhaust gas discharged into one chamber that enters the other chamber through the communication hole can be reduced. Although it becomes limited,
The penetration of pulsating waves will be freely allowed. Therefore, the exhaust gas discharged into one chamber is less likely to flow back into the exhaust pipe of the other chamber, so that the original improvement in output by utilizing the pulsation effect is not inhibited.

In addition, since the wall rigidity of the shell-structured sound deadening chamber is increased by the internal installation of the partition plate, it is possible to reduce the occurrence of shell noise due to vibration.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an exhaust system according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of FIG. 1, and FIG. 3 is a cross-sectional view of FIG. 1. 1... Exhaust pipe, 2... Silence chamber, 3... Silence pipe, 4... Ciel, 5... Partition plate, 5a... Communication hole.

Claims (1)

[Claims] 1. In a motorcycle having an exhaust system in which a plurality of exhaust pipes extending from each cylinder of a multi-cylinder engine are connected to a silencing chamber made of a hollow shell structure, and a plurality of silencing pipes are further connected to the silencing chamber, the interior of the silencing chamber is is divided into left and right chambers by a partition plate in the front and rear direction, and a communication hole is provided in the partition plate to communicate the left and right chambers, and a plurality of exhaust pipes extending from each cylinder are bisected on the front wall side of each chamber. An exhaust system for a motorcycle, characterized in that each chamber has a connection opening and the muffler pipe is connected to a rear wall side of each chamber.