JPS59218322A - Muffler for internal-combustion engine - Google Patents

Abstract

PURPOSE:To reduce the number of parts and reduce cost in a muffler formed by integrally combining two pieces of sheet metal from both sides, by forming expanded chambers at a central portion and an exhaust gas passage around the expanded chamber. CONSTITUTION:In a muffler formed by integrally combining two pieces of sheet metal 10a and 10b from both sides, there are formed recesses 2a and 2b at a central portion to provide an expanded chambers 1 and 2. At an outer peripheral portion of the expanded chambers, there are formed grooves 5a and 5b communicating with the recesses at a part thereof to provide an exhaust gas passage 5. With this arrangement, it is possible to reduce the number of parts when various pipes such as an exhaust pipe and a resonance pipe are mounted to the muffler.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a muffler for an internal combustion engine made of sheet metal, and particularly to a muffler suitable for an engine mounted on a small motorcycle such as a scooter.

At least two sheets of metal molded into four parts are used as a silencer for engines mounted on small motorcycles such as scooters.
・There is one that is integrated into the body and the concave part is formed into an expansion chamber. When connecting a longer exhaust pipe or attaching a resonance pipe to such a muffler, the number of parts and the number of man-hours required for the pipes increase, causing an increase in costs.

The purpose of the present invention is to provide a muffler for an internal combustion engine that can be manufactured at low cost by reducing the number of parts in order to provide exhaust performance and pipes such as a resonance pipe to the above-mentioned sheet metal muffler. This is what we aim to provide.

To achieve the above object, the present invention is a muffler for an internal combustion engine, in which a recess is formed inside the sheet metal, leaving the outer periphery, and the recess is formed into an expansion chamber by combining at least two of the sheet metals from the left and right sides. In this method, a groove is formed in the outer circumferential portion of the metal sheet so that a part thereof communicates with the four parts, and the groove is configured to form an exhaust gas passage by combining the metal sheets.

Hereinafter, the present invention will be explained with reference to embodiments shown in the drawings.

In FIGS. 1 and 2, 1 is the first expansion chamber of the silencer;
Similarly, 2 is a second expansion chamber. First and second expansion chambers1.
2 are separated by a partition plate 3 and communicated with each other by a communication pipe 4. An exhaust gas passage 5 is formed surrounding the outer periphery of the expansion chamber 1.2, and the inlet end of the exhaust gas passage TjPf5 is connected to an exhaust pipe 7 of the engine (not shown), and the outlet end is connected via a pipe 6. It communicates with the first expansion chamber 1. 8 is a tail pipe that releases the muffled exhaust gas into the atmosphere.

The above-mentioned silencer is constructed by integrating two sheet metals 10a and 10b from the left and right sides, and welding the base surfaces thereof. These sheet metals 10a, 10b are formed into four parts 2a, 2b in the part corresponding to the expansion chamber 1.2, and grooves 5a, 5b in the part corresponding to the exhaust gas passage 5, which are combined into one piece. By doing so, the expansion chamber 1.2 and the exhaust gas passage 5
It is designed to be.

FIGS. 3 and 4 show other embodiments. In this embodiment, the exhaust gas passage 5' provided on the outer periphery of the first expansion chamber 1 and the second expansion chamber 2 is a resonance tube with a closed tip. In this case as well, two sheets of metal 108. Recesses 2a, 2b and grooves 5'' formed on IOt+, respectively
+5'', which together form an expansion chamber 1.2 and an exhaust gas passage 5'', respectively.

In this embodiment, a valve 11 is installed 3 at the inlet of the exhaust gas passage 5°, which is a resonance tube. This valve 11 is opened and closed by a control unit 12 which inputs an engine rotational speed signal I) and issues a control signal, and is closed when the engine rotates at high speed and opened when the engine rotates at low speed. ing.

The exhaust gas passage 5', which is a resonance pipe, generates exhaust pulsation by reflected waves of the exhaust gas, which acts on the bleed pipe 7. This exhaust pulsation has the characteristic that it reduces engine output and torque at low speeds, but reduces it at high speeds. Therefore, by opening the valve 11 at low speeds and closing it at high speeds as described above, performance can be improved at both low speeds and iRi speeds compared to an engine without a resonance tube.

Now, in each of the first and second embodiments described above, when attaching exhaust gas pipes such as exhaust pipes and resonance pipes to the muffler, the expansion chambers 1 and 2 are attached to the sheet metals ioa and 10b. In addition to the corresponding four parts 2a and 2b, there is also a groove 5a+ on the outer periphery.
5 b + 5 a'.

5b', and when at least two of them are combined into one body, an exhaust gas passage 5, 5' corresponding to the above-mentioned pipes is formed. Therefore, the above-mentioned pipes can be provided without substantially increasing the number of parts and without increasing the number of installation steps.

In the embodiment, the silencer is assembled by combining two metal sheets, but it is of course possible to use three or more metal sheets.

As described above, the present invention provides a muffler for an internal combustion engine, in which four parts are formed inside a sheet metal, leaving the outer periphery, and the four parts are formed into an expansion chamber by combining at least two of the sheet metals from the left and right sides. A groove is formed in the outer circumference of the sheet metal so that a part of the groove communicates with the recess, and the groove is combined with the sheet metal to form an exhaust gas passage. Or when installing tubing such as a resonance pipe,
It can be manufactured at low cost without increasing the number of parts.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a silencer according to an embodiment of the present invention, and FIG.
3 is a vertical cross-sectional view of a silencer showing another embodiment of the present invention. FIG. 4 is a view taken along the line IV-I in FIG. 3.
It is a V arrow view. 1..First expansion chamber, 2..Second expansion chamber, 5°5”・
・Exhaust gas passage, 2a, 2b... recesses 1.5a, 5b
, 5a'5b' - Concave groove, 10a. iob... Sheet metal. Agent: Patent Attorney Makoto Ogawa − Patent Attorney: Kido Noguchi Teru Patent Attorney: Kazuhiko Saishita

Claims (1)

[Claims] In a silencer for an internal combustion engine, a recess is formed inside the sheet metal while leaving the outer periphery, and at least two of the sheet metals are integrated from the left and right to form the four parts into an expansion chamber. 1. A muffler for an internal combustion engine, characterized in that a groove is formed such that a portion communicates with the recess, and the groove forms an exhaust gas passage by combining sheet metals.