| 摘要 |
PROBLEM TO BE SOLVED: To quickly raise the catalist temperature while a large quantity of unburned HC, CO is prevented from being discharged from a catalyst. SOLUTION: A three-way catalyst 13 is arranged in an exhaust path of an internal combustion engine having four cylinders. When the catalyst temperature is high, fuel is supplied to all the cylinders to operate all the cylinders. When the catalyst temperature is low, the fuel supply to some of the cylinders is stopped so that the air discharged from the stopped cylinders flows into the three-way catalyst 13 together with the exhaust gas discharged from the remaining operating cylinders. At this time, the quantity of fuel supplied to the operating cylinders is controlled so that an average air fuel ratio of the exhaust gas flowing in the three-way catalyst 13 is a stoichiometric air fuel ratio, or slightly lean.
|
