Exhaust gas purification filter

An exhaust gas purification filter, having external dimensions, disposed in an exhaust passage of a gasoline engine, comprising:

• a cell assembly having an outer surface and including:
• a plurality of cells each disposed to extend in an axial direction of the filter, each of the cells having opposing first and second ends in the axial direction, and
• a partition wall configured to have a porous structure and define the plurality of cells partitioned from each other in a grid pattern;
• a plurality of seal members disposed alternately in the first and second ends of the respective cells, each of the seal members being configured to seal a corresponding one of the first end and the second end of a corresponding one of the cells of the cell assembly;
• and
• a skin member configured to have a tubular shape and be mounted on the outer surface of the cell assembly, wherein:
• the partition wall has a porosity of 50% to 70%,
• the skin member has a thickness T of 0.3 mm to 1.0 mm,
• the partition wall includes a plurality of crossing portions,
• each of the cells has at least one part of an outer periphery defined by a corresponding one of the crossing portions,
• the at least one part of the outer periphery of each of the cells is rounded to have a value of radius of curvature R being 0.02 mm to 0.6 mm,
• a degree of distortion δ, which is a degree of change in the external dimensions of the exhaust gas purification filter in the axial direction, is greater than 0 and is 1.5 mm or less, and
• a value of a structural variable X, expressed by Equation 1 below, is 0.05 to 6,
• X=T×R/δ Equation 1.