| 摘要 |
PROBLEM TO BE SOLVED: To provide a honeycomb filter which can prevent the nonuniform closure of cells in the filter caused by a filtration residue, etc., and give a uniform reverse cleaning pressure to each cell. SOLUTION: In the honeycomb filter, a porous body of honeycomb structure having numbers of the cells is made a base material, and at least one layer of a filter membrane whose pore diameter is smaller than that of the porous body is provided. In the flow resistance indexλof each cell in the filter defined by formula (1):λ=(λC×TC/LC)+[(λB×LB/TB)×(LB/P)/2]+[(λB×LD/TB)×(LB/P)] (1) (wherein,λis the flow resistance index of an object cell;λC is the basic resistance of the filter membrane; TC is the thickness of the filter membrane; LC is the inner circumference length of the filter membrane;λB is the basic resistance of the base material; LB is the shortest distance from the object cell to an external space; TB is the rib thickness of the base material; P is the cell forming pitch of the filter; LD is the outer wall part thickness of the base material), the ratio between the minimum valueλmin and the maximum valueλmax is made 1/1-1/50.
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