JPS6027766Y2 - Internal combustion engine exhaust silencer - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a device for muffling the exhaust noise of an internal combustion engine such as an engine mounted on a motorcycle.

A conventional exhaust muffling device in which exhaust gas is guided in the circumferential direction of the muffler body by a spiral plate to cause expansion is known, for example, from Japanese Patent Application Laid-Open No. 48-67635. In a shaped muffler, swirl is given to the exhaust flow coming out of the swirl plate, so if a wall is placed around the outer circumference of the swirl plate to prevent the swirl of the air flow, the flow resistance of the exhaust gas will increase and the engine output will decrease. .

This idea was devised based on the above-mentioned circumstances, and its purpose is to easily create a swirling flow of exhaust gas at the outer circumferential portion of the spiral plate, and to make it possible to easily create a swirling flow of exhaust gas at the outer circumferential portion of the spiral plate. An object of the present invention is to provide an exhaust muffler for an internal combustion engine in which the flow resistance of the engine is reduced as much as possible.

An embodiment of this invention will be described below regarding an exhaust muffling device for a motorcycle, which is shown in the drawings.

Reference numeral 1 in FIG. 1 denotes a first muffler serving as a first-stage expansion chamber whose inlet is connected to an exhaust pipe 2. The inlet side portion of a connecting pipe 3 is inserted and fixed into the outlet of this muffler. A side branch 4 is provided protruding from the intermediate portion via a fixture 5.

Then, the insertion dimension A of the connecting pipe 3 into the first muffler 1
and the dimension B of the side branch 4 are different,
These are the wavelengths of certain low sound waves in the exhaust sound that you want to muffle.
The length is set to 174.

Further, the outlet of the connecting pipe 3 is connected to the inlet of the second muffler 6.

To explain this second muffler 6 in detail, reference numeral 7 in FIGS. 1 and 2 is a muffler main body, on one end of which an inlet end plate 8 connected to the connecting pipe 3 is attached, and on the other end. The diameter is reduced using a spatula diaphragm, etc., and the outlet is used.

Inside this main body 7, two partition walls 10 and 11 each having a fine communication pipe 9 are attached, and a sound deadening unit 1
2 is installation.

The unit 12 has a shape formed by a first end plate 13 and a second end plate 14 facing each other, a spiral plate 15 installed between these, and a discharge pipe 16 protruding from the center of the rear surface of the second end plate 14. It is.

The first end plate 13 is provided with its outer peripheral edge in contact with the inner peripheral surface of the muffler main body 7, and an inlet hole 17 is provided in the center thereof.

Further, the second end plate 14 is provided with an annular gap 19 on its outer periphery, and its peripheral edge is preferably bent horizontally toward the rear to form a U-shaped cross section.

That is, the peripheral edge portion 18 is spaced apart from the inner circumferential surface of the muffler main body 7, and an annular outlet is formed therebetween.

The second end plate 14 also has a rear end of the discharge pipe 16 connected to the muffler main body 7.
is supported by fixing it to the outlet of the

Note that this discharge pipe 16 is provided with a large number of holes 20.

Further, the spiral plate 15 is formed of a fairly wide metal plate, has a large number of small holes 21, and has its center facing the inflow hole 17, and both ends thereof. are fixed to the first and second end plates 13,14.

According to this exhaust muffler, the exhaust gas introduced from the exhaust pipe 2 is transmitted through the first muffler 1, the inlet end plate 8 in the second muffler 6, the partition walls 10 and 11, and the first end plate 13. The connection pipe 3, the communication pipes 9, 9, the inlet hole 17, the gap 1
9 and the discharge pipe 16.

In other words, the exhaust gas expands and contracts repeatedly in this way, and is discharged with its temperature and pressure reduced to almost atmospheric conditions.

In addition, since the discharge pipe 16 is disposed at the center of the rear end of the muffler main body 7, the outlet is located at the center of the rear face of the second muffler 6, which has a favorable effect in terms of design.

Furthermore, in this exhaust silencer, the insertion part of the connecting pipe 3 into the first muffler 1 and the side branch 4 can muffle the sound in the low frequency range of the exhaust sound, and the sound muffler in the second muffler 6 can muffle the sound in the low frequency range of the exhaust sound. The unit 12 can muffle sounds in the middle to high frequency range of the exhaust sound, thus making it possible to muffle the entire sound range.

Further, the flow of exhaust gas after the muffling unit 12 is as explained below.

That is, the exhaust gas that has been throttled through the inflow hole 17 and entered the center of the spiral plate 15 expands while flowing along the spiral plate 15, and during this time, the exhaust gas flows through the small holes 21...
The sound is interfered with through the annular gap 19, and then flows out through the annular gap 19.

In this case, since the gap 19 diverts the exhaust gas in the axial direction without blocking the flow in the circumferential direction, the vortex flow of the exhaust gas can flow through the gap 19 without significantly reducing its momentum.

Moreover, when the exhaust gas passes through the gap 19, the flow is rectified by the inner circumferential surface of the muffler main body 7 and the peripheral edge portion 18 of the second end plate 14.

The exhaust gas flowing through the gap 19 is reflected by the rear end wall of the muffler main body 7, but in this case, the flows are separated by the peripheral edge of the second end plate 14 so that they do not interfere with each other.
Exhaust gas is quickly distributed.

Further, according to the structure of this noise reduction unit 12, since the spiral plate 15 is supported at both ends by the first end plate 13 and the second end plate 14, the spiral plate 15 is prevented from vibrating due to the pulsation of exhaust gas pressure. It is possible to prevent this, and to extend the life of the silencing unit 12.

In addition, since the member supporting the second end plate 14 is the exhaust pipe 16, a noise reduction effect can also be obtained by the exhaust pipe 16.

As explained above, this device forms an annular air gap as an outlet between the spiral plate and the second end plate provided at its rear end and the inner circumferential surface of the muffler body. This does not create a large resistance to the flow of exhaust gas flowing out.

Therefore, it is easy for the exhaust gas to expand in the swirl plate portion, which has the practical effect of reducing back pressure, effectively muffling exhaust noise, and minimizing a decrease in engine output.

[Brief explanation of the drawing]

The drawings show an embodiment of this invention, and FIG. 1 is a longitudinal sectional view;
FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1. 6... Second silencer, 7... Silencer main body, 12... Sound deadening unit, 13... First end plate, 14... ...Second end plate, 15...
Swirl plate, 16...Discharge pipe, 17...
Inflow port, 18...Periphery of second end plate, 19...
...Void, 20...hole.

Claims (1)

[Scope of utility model registration request] A first end plate 13 whose outer peripheral edge is in contact with the inner peripheral surface of the muffler body and has an inflow hole in the center;
A second end plate 14 provided within the silencer main body to face and be spaced from the end plate.
In addition, a spiral plate 15 is installed to guide the exhaust gas flowing from the inlet hole along the circumferential direction of the muffler body.
An exhaust muffler for an internal combustion engine, in which an annular gap 19 is provided between the outer peripheral edges of the end plate and the spiral plate and the inner peripheral surface of the muffler main body.