CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

This control device for an internal combustion engine equipped with an exhaust purification catalyst (20), which is disposed in an exhaust passage of the internal combustion engine and capable of storing oxygen, includes: a downstream air-fuel ratio detection means that is disposed downstream of the exhaust purification catalyst in the exhaust flow direction; and an inflow air-fuel ratio control means that controls the air-fuel ratio of exhaust gas flowing into the exhaust purification catalyst. If the outflow air-fuel ratio detected by the downstream air-fuel ratio detection means is equal to or less than a rich-determination air-fuel ratio, which is richer than the stoichiometric air-fuel ratio, the inflow air-fuel ratio control means sets the target air-fuel ratio of exhaust gas flowing into the exhaust purification catalyst continuously or intermittently leaner than the stoichiometric air-fuel ratio until the oxygen storage amount of the exhaust purification catalyst reaches a prescribed storage amount. If the oxygen storage amount of the exhaust purification catalyst is equal to or greater than the prescribed storage amount, the inflow air-fuel ratio control means sets the target air-fuel ratio continuously or intermittently richer than the stoichiometric air-fuel ratio until the oxygen storage amount decreases toward zero without reaching the maximum oxygen storage amount.