Patent ID: 6336320
Filing Date: 2002-01-08
Classification: F01N,F02D,Y02T

Abstract:
An exhaust gas purification device for an internal combustion engine which operates at a lean operating air-fuel ratio and a stoichiometric operating air-fuel ratio or a rich operating air-fuel ratio as required, comprising:an exhaust gas purifying catalyst disposed in an exhaust gas passage of the engine and having an O2 storage capability; and a storage decreasing means for decreasing the amount of oxygen stored in said exhaust gas purifying catalyst by feeding the fuel that does not contribute to the combustion to the engine so that the air-fuel ratio of the exhaust gas flowing into said exhaust gas purifying catalyst is more enriched than the engine operating air-fuel ratio when the engine operating air-fuel ratio is to be changed from a lean air-fuel ratio to the stoichiometric air-fuel ratio or a rich air-fuel ratio.