Patent ID: 8001765

Claim:
An exhaust gas purifying apparatus for an internal combustion engine, comprising: a catalyst provided in an exhaust gas passage of the internal combustion engine; an upstream side exhaust gas air-fuel ratio detector provided in an upstream side of the catalyst, a downstream side exhaust gas air-fuel ratio detector provided in a downstream side of the catalyst, a fuel cutter that temporally stops a fuel supply to the internal combustion engine; a rich change executor that executes changing of an air-fuel ratio of the internal combustion engine to a rich air-fuel ratio after the fuel supply is once stopped by the fuel cutter and then resumed; a setter that sets up a correlation value correlated to a degree of the changing to the rich air-fuel ratio by the rich change executor in accordance with a driving condition of the internal combustion engine; a corrector that corrects the correlation value set by the setter, on the basis of a period from a time point that the upstream side exhaust gas air-fuel ratio detector detects that the exhaust gas air-fuel ratio converges on the stoichiometric ratio until a time point that the downstream side exhaust gas air-fuel ratio detector detects that the exhaust gas air-fuel ratio is the rich air-fuel ratio; and a controller that controls the rich change executor to execute the next changing in accordance with a correction result of the corrector.