Exhaust purification device of an engine

摘要

An exhaust purification device of an engine providing a NOx absorbent arranged in the exhaust passage. An O2 sensor generating a current proportional to the air-fuel ratio is arranged in the engine exhaust passage downstream of the NOx absorbent. The amount of NOx actually absorbed in the NOx absorbent at the time of release of the NOx is calculated on the basis of the output signal of this O2 sensor. On the basis of this calculated amount of NOx, correction is made so that the estimated amount of NOx represents the actual amount of absorption of NOx. When this corrected estimated amount of NOx reaches a set value, the action of releasing the NOx from the NOx absorbent is carried out.