Patent ID: 7553442

Claim:
A method of manufacturing an exhaust gas purifying filter, made of a ceramic material in a honeycomb structure, comprising introduction passages for introducing exhaust gas that includes particulate matter emitted from an internal combustion engine, porous walls that collect said particulate matter and exhaust passages for exhausting the exhaust gas after the particulate matter has been removed therefrom, with said porous walls supporting a catalyst for oxidizing and removing said particulate matter, the porosity of the porous walls being in a range from 55 to 80%, and mean pore size being in a range from 30 to 50 μm, while the total volume X of the pores included in said exhaust gas purifying filter and the volume Y of the pores that are not smaller than 100 μm satisfy the relation of inequality Y/X≦0.05 wherein said exhaust gas purifying filter is made by firing a preform that is formed in honeycomb structure from a mixture of ceramic powder and a foaming material so that the foaming material expands during the firing process, and adding the catalyst to be supported thereon, and said foaming material is a mixture of a material of which 5 to 80% has been already expanded and an unexpanded material that expands at a temperature not higher than 100° C.