Patent ID: 7238217

Claim:
A ceramic honeycomb wall flow filter comprising an array of parallel channels separated by porous channel walls running parallel with a central filter axis in a gas flow direction from a gas inlet end to a gas outlet end of the filter, (i) the array comprising a plurality of inlet channels closed at the gas outlet end separated by the porous channel walls from a plurality of outlet channels closed at the gas inlet end, thus to provide a gas flowpath from the inlet channels through the channel walls to the outlet channels, (ii) the channel walls of an axial group of inlet and outlet channels disposed along the central filter axis have at least one of (a) a higher heat capacity and (b) a higher gas flow resistance than the channel walls of a peripheral group of inlet and outlet channels disposed peripherally of the axial group of channels, with the average thickness of the channel walls of the axial group of inlet and outlet channels being greater than the average thickness of the channel walls of the peripheral group of inlet and outlet cells, (iii) the cell density of the axial group of inlet and outlet channels is substantially equivalent to the cell density of the peripheral group of inlet and outlet channels, (iv) the average outlet channel cross-sectional area in the axial group is smaller than the average outlet channel cross-sectional area in the peripheral group, and (v) the average inlet channel cross-sectional area in the axial group is substantially equivalent to the average inlet channel cross-sectional area in the peripheral group.