Acoustics – Sound-modifying means – Muffler – fluid conducting type
Reexamination Certificate
2002-03-12
2003-12-30
Nappi, Robert E. (Department: 2837)
Acoustics
Sound-modifying means
Muffler, fluid conducting type
C181S264000
Reexamination Certificate
active
06668973
ABSTRACT:
The present invention relates to a transverse partition for separating an exhaust volume into two adjacent chambers, the partition being of the type comprising at least one passage for allowing gas to flow between the two chambers, the gas flow section through the passage being modifiable under drive from the difference between the pressures on the two sides of the partition.
BACKGROUND OF THE INVENTION
In exhaust mufflers, it is known to define two adjacent chambers that are separated by a transverse partition, the chambers being capable of being put into communication with each other automatically at high engine revolutions.
For this purpose, a flap valve is installed on the transverse partition extending across the exhaust muffler and separating the two adjacent chambers.
By way of example, such a valve is described in Japanese patent application JP-08004990. That valve comprises a seat defining a gas flow passage and a flap hinged to an edge of the seat. The flap can be moved between a closed position where it bears against the seat and a position in which it is spaced apart from the seat allowing gas to flow freely. A spring is provided to urge the flap towards its closed position. The flap is moved away from the seat under drive from the difference between the pressures in the two chambers.
The valve structure described in that document is very complex and it incorporates a large number of parts, thereby considerably increasing the cost of manufacturing an exhaust muffler that incorporates it.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the invention is to propose a transverse partition for an exhaust volume that allows gas to pass through in controlled manner and that can be manufactured at very low cost, and also to propose an exhaust muffler incorporating it.
To this end, the invention provides a transverse partition of the above-specified type for separating an exhaust volume into two adjacent chambers, the partition comprising a wall pierced by at least one slit defined between two adjacent edges of the wall, which wall is elastically deformable under drive from the pressure difference between the two sides of the partition, between a rest position in which wall continuity is ensured, the two edges of the slit being substantially touching, and a deformed position in which the two edges of the slit are spaced apart so as to define said gas flow passage between them.
In particular embodiments, the partition includes one or more of the following characteristics:
said wall is generally plane;
said slit is generally spiral-shaped;
said wall is generally cylindrical;
said slit is generally helically shaped;
said generally cylindrical wall is closed at one of its ends;
the partition comprises a generally plane main panel, and said generally cylindrical wall extends perpendicularly to said panel;
one of the surfaces of the generally cylindrical wall is covered by a gas-permeable sheath, in particular a braid;
said slit is wound around at least two turns;
the thickness of the region of the wall in which the slit is defined is greater than the average thickness of said partition; and
the thickness of the wall region where the slit is defined is greater than the average thickness of said partition.
The invention also provides an exhaust muffler defining an enclosure and including at least one transverse partition as defined above, said partition defining two adjacent chambers within the enclosure.
REFERENCES:
patent: 4177875 (1979-12-01), Kurobe et al.
patent: 4580656 (1986-04-01), Fukuda
patent: 08189329 (1996-07-01), None
Grandmougin Michel François Roland
Scanavin Jean-Luc
Faurecia Systemes d'Echappement
McCloud Renata D
Sughrue & Mion, PLLC
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