Engine exhaust gas purification device

摘要

An exhaust gas purification device comprising a three way catalyst, an oxidizing catalyst and a NOx absorbent which are arranged in this order in the exhaust passage. A rich air-fuel mixture is burned in the combustion chamber, and secondary air is supplied upstream of the three way catalyst so as to make the air-fuel ratio of the exhaust gas flowing into the three way catalyst a rich air-fuel ratio greater than the air-fuel ratio of the air-fuel mixture burned in the combustion chamber. Further, secondary air is supplied upstream of the oxidizing catalyst to make the air-fuel ratio of the exhaust gas flowing into the oxidizing catalyst and the NOx absorbent slightly leaner than the stoichiometric air-fuel ratio.