Exhaust emission control apparatus for internal combustion engine

An exhaust emission control apparatus comprising:

• an electrically heatable catalytic converter mounted in an exhaust passage of an internal combustion engine, said catalytic converter having a catalyst for catalytic conversion of exhaust gases from said engine and a heating element for heating said catalyst to accelerate a rate of the catalytic conversion;
• a power supply for applying electric power to said heating element for heating said catalyst;
• time setting means for calculating a time period during which electric power is applied to said heating element, said time period being calculated based on at least a heat capacity of the catalytic converter, a consumption power of the catalytic converter, a preset standard temperature of the heating element and a temperature of cooling water in said engine;
• and
• control means for controlling application of electric power from said power supply to said heating element in accordance with the time period calculated by said time setting means in a way that the application of electric power to the heating element is stopped when said time period since the application of electric power to the heating element is started has elapsed.