Gas separation: apparatus – With sound damping means – Sound attenuating gas flow path
Reexamination Certificate
2000-05-31
2001-12-04
Smith, Duane S. (Department: 1724)
Gas separation: apparatus
With sound damping means
Sound attenuating gas flow path
C096S385000, C055S467000, C055SDIG003
Reexamination Certificate
active
06325844
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a filter for mechanisms which vacuum, and more particularly to a filter and muffler device which is externally attached to an outlet port of a vacuum mechanism to reduce particulates or duct particles escaping from the outlet port and additionally to reduce noise emanating from the outlet port.
BACKGROUND OF THE INVENTION
The use of HEPA filters in a vacuum device, such as wet/dry vacuums, is known in the art. In addition, the use of separately attachable filter to an exhaust of a vacuum is also known. However, while such separately attachable filters may act to muffle sound, they do not do so efficiently or effectively.
BRIEF SUMMARY OF THE INVENTION
In accordance with the present invention, a filter and muffler device for use with a vacuum mechanism having an outlet port is provided. The filter and muffler device is particularly designed to muffle sound exiting from the outlet port as well as to filter the exhaust of the vacuum mechanism. The device includes a filter element which is generally rectangular in plan view and which has opposed lateral sides and opposed longitudinal sides. The filter element has a direction of filtration from a planar inlet side or bottom to a planar outlet side or top thereof, and is preferably a HEPA type filter.
The device also includes a housing in which the filter element is located. This housing includes a generally flat upper wall parallel to and spaced from the top of the filter element; respective lateral and longitudinal side walls connected to the upper wall and extending generally parallel to the respective lateral and longitudinal sides of the filter element; and a lower wall spaced from the upper wall, extending between the lateral and longitudinal side walls of the housing, and located opposite the bottom of the filter element. This lower wall has a lateral peak which produces a trochoidal shape so that the lower wall includes a major surface and a minor surface. The housing also includes an inlet port extending outwardly from the minor surface of the lower wall which is adapted to be mounted to the outlet port of the vacuum device, a mounting means for mounting the filter element sealingly between the upper wall and the lower wall, and spaced exhaust ports located adjacent the upper wall.
In a preferred embodiment, the filter and muffler device further includes a middle baffle provided between the longitudinal side walls of the housing and between the planar top of the filter element and the upper wall of the housing. The middle baffle preferably contacts the top of the filter element at a lateral center thereof and extends to the longitudinal sides of the housing from the lateral center at an acute angle to the upper all so that a small passage underneath the middle baffle is provided. The middle baffle also preferably includes a lateral passage therethrough adjacent one of the longitudinal sides of the housing.
In the preferred embodiment, the exhaust ports of the housing include (a) a first lateral exhaust opening located adjacent an intersection of the upper wall and the lateral side wall which is adjacent the minor surface of the lower wall, (b) a second lateral exhaust opening located adjacent an intersection of the upper wall and the lateral side wall which is adjacent the major surface of the lower wall, and (c) third and fourth exhaust openings located adjacent an intersection of the upper wall and a first one of the longitudinal side walls. Preferably, the respective intersections of the upper wall and the lateral side walls are curved, and the device further includes respective first and second end baffles extending inwardly from each respective lateral wall underneath of the respective first and second openings. In addition, an intersection of the upper wall and a second one of the longitudinal side walls is unbroken with any openings. For best sound muffling, the inlet port of the housing is located offset from a lateral center of the minor surface and towards the second one of the longitudinal side walls of the housing, such as being offset by about 12-20% of a width of the housing. The inlet port is also tapered inwardly toward a distal end thereof so as to be adapted to provide a friction fit with outlet ports of vacuum devices of various sizes.
Also in the preferred embodiment, the major surface of the lower wall extends at an angle of 14-18° to the upper wall, and the minor surface of the lower wall extends at an angle of 6-10° to the upper wall. In addition, the longitudinal side walls include respective lower ledges extending inwardly therefrom which respectively engage the planar bottom of the filter element to locate the filter element thereon.
It is an advantage of the present invention that an effective filtering and muffling is achieved in a single device.
It is also an advantage of the present invention that the device is usable on a variety of vacuum devices as an easily installed add-on.
It is another advantage of the present invention that the device is specifically designed to reduce acoustic levels in the 2,000-8,000 Hz range which is the most audible to the human ear.
Other features and advantages of the present invention are stated in or apparent from a detailed description of a presently preferred embodiment of the invention found hereinbelow.
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Lindsay William S.
Mead Donald R.
Florida Pneumatic Manufacturing Corporation
Larson & Taylor PLC
Smith Duane S.
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