Acoustics – Sound-modifying means – Housing or enclosure
Reexamination Certificate
1999-12-17
2001-08-14
Dang, Khanh (Department: 2837)
Acoustics
Sound-modifying means
Housing or enclosure
C181S202000, C181S204000
Reexamination Certificate
active
06273213
ABSTRACT:
TECHNICAL FIELD
The present invention relates to improvements in noise suppression apparatus, and more particularly, to an engine enclosure having a louver formed by intersecting horizontal and vertical passive sound absorptive slats.
BACKGROUND ART
Enclosures for internal combustion engines, such as those used on earthmoving machines and mobile power stations, are designed to minimize the sound levels outside the engine compartment. Typically this is accomplished by adding sound insulation to the wall of the enclosure. However, the engine enclosure must allow for sufficient inlet and exit airflow capacity is to support combustion and to provide cooling air for the engine. Air inlets are provided in the enclosure walls, thereby significantly increasing the sound levels outside the compartment.
It is known in the art to cover the enclosure air inlets and exits with a louver formed of sound absorptive material, typically in the shape of straight or V-shaped slats. It should be noted that although the term “louver” may refer both to a slatted opening and to the slats the themselves, this description for the sake of clarity defines it to be limited to the first described usage.
A problem with this type of silencer is that a trade-off must be made between the desired noise attenuation and the air pressure drop across the panel. If the slats are placed in close proximity to one another, substantial broad-band noise reduction can be accomplished, but tending to increase the pressure loss across the panel and thereby reduce the combustion or cooling airflow through the engine compartment. An increase in fan speed to compensate for the lost airflow increases the fan noise, even to the point of eliminating any net gain in noise attenuation. The present invention is directed to methods and apparatus for addressing one or more of the problems set forth above.
DISCLOSURE OF THE INVENTION
A noise suppression louver is provided for an engine enclosure having an air opening. The louver includes a first plurality of slats extending substantially horizontally across the air opening, and a second plurality of slats extending substantially vertically across the air opening and intersecting the first plurality. The first and second plurality of slats include a passive sound absorptive material.
In another embodiment, a plurality of walls form a compartment enclosing an internal combustion engine and provide at least one air opening into the compartment. The engine includes an axial flow fan for moving air within the compartment. A radiator assembly circulates coolant to and from the engine.
A louver is provided having a plurality of intersecting vertical slats and horizontal slats extending across the air opening of the engine compartment, each slat including passive sound absorptive material to attenuate engine noise transmitted through the opening.
Other details and advantages of the invention will become apparent by reference to the following description and illustrative drawings of certain present embodiments thereof and certain present preferred methods of practicing the same proceeds.
REFERENCES:
patent: 2759555 (1956-08-01), Baruch
patent: 3762489 (1973-10-01), Proksch et al.
patent: 3897850 (1975-08-01), Thompson et al.
patent: 3923114 (1975-12-01), Suzuki
patent: 4334588 (1982-06-01), Tezuka et al.
patent: 4335797 (1982-06-01), Simmons
patent: 5625172 (1997-04-01), Blichmann et al.
Callas James J.
Copley David C.
Damotte Emile E.
Stoeckel Kristian M.
Caterpillar Inc.
Dang Khanh
Kibby Steven G.
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