EXHAUST PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

An internal combustion engine in which a front end catalyst (12) and rear end catalyst (14) comprising NO x storing catalysts are arranged in an engine exhaust passage. When these catalysts (12, 14) should recover from SO x poisoning, SO x poisoning recovery proceeding is performed in which the temperatures of the corresponding catalysts (12, 14) are raised to the SO x release temperature and the air-fuel ratio of the exhaust gas flowing into the corresponding catalysts (12, 14) is made rich. In this case, the frequency of performing the SO x poisoning recovery proceeding of the rear end catalyst (14) is made higher than the frequency of performing the SO x poisoning recovery proceeding of the front end catalyst (12).