| 摘要 |
PROBLEM TO BE SOLVED: To reduce emission of hazardous gases by maintaining a purification ratio of NOx in lean burn exhaust gas from an internal combustion engine constantly at or above a predetermined level. SOLUTION: Under control where a NOx adsorption catalyst is disposed in an exhaust gas passage, NOx is adsorbed in an oxidization atmosphere of lean burn exhaust gas, and the NOx adsorption catalyst is regenerated in a reduction atmosphere, NOx reduction process is performed according to a calculated NOx adsorption amount. The NOx adsorption amount is calculated excluding an amount of the exhaust gas directly reduced to N2. |
