Exhaust gas purifier for internal combustion engine

An exhaust gas purifier, comprising:

• a particulate filter disposed in an engine exhaust system for collecting particulates;
• a reversing device that reverses an exhaust upstream side and an exhaust downstream side of the particulate filter;
• and
• a catalyst device arranged adjacent to the particulate filter at a position always being at the exhaust gas downstream side of the particulate filter,
• wherein the collected particulates at the particulate filter are oxidized, the particulate filter includes a collecting wall for collecting the particulates, the collecting wall has a first collecting surface and a second collecting surface, and wherein the first and the second collecting surfaces are alternately used for collecting particulates by reversing the exhaust gas upstream side and the exhaust gas downstream side of the particulate filter by the reversing device.