Muffler for exhaust gas from an internal combustion engine

Details Muffler for exhaust gas from an internal combustion engine Muffler for exhaust gas from an internal combustion engine

1983-07-05

1985-06-18

Fuller, Benjamin R.

Acoustics

Sound-modifying means

Muffler, fluid conducting type

181252, 181256, 181272, F01N 110

Patent

active

045236623

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to a muffler of the absorption type for exhaust gas from an internal combustion engine. The muffler is composed of a cylindrical porous sound-absorbing material having a film of, for example, glass, rock or steel wool, or a porous ceramic or metallic material. It utilizes the basic advantages of the absorption type structure which reside in an improvement in fuel consumption and engine output, while overcoming its drawbacks by preventing the clogging of the cylindrical porous sound-absorbing material and imparting a greater scope of sound-absorbing capacity thereto.


BACKGROUND ART

Glass, rock or steelwool, and a porous ceramic or metallic body are, for example, well known as the sound-absorbing material in a muffler for a machine in general.
FIG. 1(a) shows a conventional muffler for exhaust gas having a cylindrical porous sound-absorbing member 1 composed of, for example, a porour metallic material, a casing 2 which houses the sound-absorbing member 1, and an exhaust gas passage 4 defined within the sound-absorbing member 1. The sound-absorbing member 1 has pores 3.
This muffler, however, has a very short life, since the soot of tarry substance resulting from the composition of gasoline or other fuel, and adhering to the surface and interior of the sound-absorbing member gives rise to its clogging and lowers its sound-absorbing capacity drastically within a relatively short time.
Therefore, the inventor of this invention has made an extensive study of the mechanism which may cause the soot in exhaust gas to adhere to the sound-absorbing member, and found various things as will hereinafter be set forth. As the sound-absorbing member is porous, exhaust gas flows into its interior. The soot in the exhaust gas is composed of fine particles having a diameter of, say, 100 to 1,000 .ANG. which is very small as compared with the diameter of the pores in the porous sound-absorbing member. As the exhaust gas flows into the sound-absorbing member, the soot enters it and adheres to its aggregate. The soot particles become larger by mutual adsorption, and clog the pores in the sound-absorbing material. The adherence of soot is promoted by the presence of, for example, water such as condensed water, or a tarry substance.


DISCLOSURE OF THE INVENTION

This invention provides a muffler for exhaust gas comprising a casing, and a cylindrical porous sound-absorbing member extending through the casing, characterized in that a cylinder formed from a film having a prescribed thickness is provided on the inner surface of the sound-absorbing member. The soot and tar which the exhaust gas passing through the sound-absorbing member contains are prvented by the film from contacting the inner surface of the sound-absorbing member and entering its interior.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(a) is a longitudinal sectional view of a conventional muffler for exhaust gas from an internal combustion engine;
FIG. 1(b) is a sectional view taken along the line A--A of FIG. 1(a);
FIG. 2(a) is a longitudinal sectional view of a muffler embodying this invention;
FIG. 2(b) is a sectional view taken along the line A--A of FIG. 2(a);
FIGS. 3(a), 3(b), 4 and 5 are views showing other embodiments of this invention;
FIGS. 6 and 7 are graphs showing the sound-absorbing capacity of the muffler according to this invention;
FIG. 8 is a longitudinal sectional view of still another muffler embodying this invention;
FIGS. 9(A) to 9(C) are graphs showing the characteristics of the muffler shown in FIG. 8;
FIG. 10 is a fragmentary enlarged longitudinal sectional view of another embodiment of this invention;
FIGS. 11 and 13 are graphs showing the characteristics of the muffler shown in FIG. 10;
FIG. 12 is a view illustrating the construction from which the characteristics shown in FIG. 11 have been obtained;
FIG. 14 is a fragmentary enlarged longitudinal sectional view of another embodiment of this invention;
FIG. 15 is a fragmentary enlarged longitudinal sectional view of still another embodiment of this i

REFERENCES:
patent: 3109511 (1963-11-01), Slayter et al.
patent: 3175640 (1965-03-01), Matsui
patent: 4211303 (1980-07-01), Matthews
patent: 4314621 (1982-02-01), Hansen
patent: 4318720 (1982-03-01), Hoggatt

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