Patent ID: 7059122

Claim:
An exhaust gas purification apparatus for an engine, comprising: a catalytic converter provided in an exhaust path of said engine and including a carrier, an HC absorbent provided on said carrier for absorbing HC in exhaust gas of said engine, a three way catalyst, containing a transition metal as a main element for absorbing CO in an exhaust gas, provided on said HC absorbent; and a control apparatus for controlling operation of said engine, said control apparatus including HC desorption timing estimation means for estimating a timing at which HC is desorbed from said HC absorbent and control means for controlling an air fuel ratio upon starting of said engine to a ratio richer than a stoichiometric air fuel ratio to start operation of said engine, changing over the air fuel ratio to a ratio leaner than the stoichiometric air fuel ratio at the timing at which the HC is desorbed based on an output of said HC desorption timing estimation means to heat the three way catalyst by making the absorbed CO react with oxygen contained in the exhaust gas, and maintaining the air fuel ratio at the ratio leaner than the stoichiometric air fuel ratio for a period of time determined based on an actual temperature of the HC absorbent.