An exhaust purification device of an engine

摘要

An exhaust purification device of an engine having an exhaust passage, comprising: a NOx absorbent arranged in the exhaust passage; air-fuel ratio control means for controlling the air-fuel ratio of the exhaust gas flowing into the NOx absorbent to temporarily change the air-fuel ratio of the exhaust gas flowing into the NOx absorbent from lean to rich at certain time intervals to release NOx from the NOx absorbent; deterioration detecting means for detecting the degree of deterioration of the NOx absorbent; wherein the relationship between the degree of deterioration of the NOx absorbent and a rich time period during which the air-fuel ratio of the exhaust gas flowing into the NOx absorbent is made rich is stored in advance, and said air-fuel ratio control means controls said rich time period on the basis of said stored relationship to shorten said rich time period as the degree of deterioration of the NOx absorbent becomes higher.