Appeal No. 1999-0551 Page 2
Application No. 08/636,431
BACKGROUND
Appellant’s invention relates to a filter element. Claims 1 and 5, the only independent claims,
and 6 are illustrative:
1. A filter element comprising:
a filter member, said filter member having an open end, a closed end, and a porous sidewall,
said side wall defining a bore which extends from a location begining at said open end and terminates at
the closed end allowing a gas to flow, said sidewall having an outer surface and an inner surface which
allow a gas to flow through;
a first membrane in communication with said outer surface for preventing particulate matter
from penetrating into said sidewall from the outer surface;
a second membrane in communication with said inner surface for preventing particulate matter
from penetrating into said side wall from the inner surface; and
wherein said first and second membranes have a finer porous structure than the sidewall.
5. A filter element comprising:
a filter member, said filter member having a porous sidewall, said sidewall having an outer
surface and an inner surface which allow a gas to flow through;
a first membrane in communication with said outer surface for preventing particulate matter
from penetrating into said sidewall from the outer surface;
a second membrane in communication with said inner surface for preventing particulate matter
from penetrating into said sidewall from the inner surface; and
wherein said first and second membranes have a finer porous structure than the sidewall.
6. The filter element of claim 5 wherein said first and second membranes are made of any one
of the group consisting of a finer porous ceramic grained material similar to the underlying support
matrix, sintered metal, a finer fibrous chopped matrix layer, a finer fibrous continuous matrix layer, a
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