| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine shortening the time when an oxygen excess air fuel ratio of exhaust gas flowing into NOx absorbent is realized in accordance with a degree of deterioration NOx absorbent and inhibitting oxygen excess air fuel ratio operation when the degree of deterioration exceeds a predetermined value. SOLUTION: This exhaust emission control device for the internal combustion engine is provided with an NOx absorbent 21 which absorbs NOx when exhaust gas is in an oxygen excess condition, discharges NOx when oxygen concentration is reduce, and is reduced and purified, an ordinary operation control means 27 switching oxygen excess air fuel ratio operation, stoichiometric air fuel ratio operation, and fuel excess air fuel ratio operation in accordance with operation conditions for operation control of the internal combustion engine, an NOx absorbent deterioration judging means 27 judging the deterioration of NOx absorbent based on a degree of NOx absorbed into the NOx absorbent, a means 27 shortening operation time when an air fuel ratio of the exhaust gas flowing into the NOx absorbent is turned into oxygen excess air fuel ratio in accordance with a degree of deterioration, and a means 27 inhibitting oxygen excess air fuel ratio operation when it is judged that the degree of deterioration exceeds a predetermined value. |
