EXHAUST AND PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

An exhaust and purification device for an internal combustion engine in which an NOx absorbent (19) is disposed in an exhaust passageway of the internal combustion engine, and an NOx oxidizing agent (18) is disposed upstream of the NOx absorbent (19) in the exhaust passageway. The NOx absorbent (19) absorbs NOx when an air-fuel ratio of exhaust gas flowing into the NOx absorbent (19) is lean and emits NOx that it has absorbed when an air-fuel ratio of exhaust gas flowing into the NOx absorbent (19) becomes a theoretical air-fuel ratio or rich. In a case where the temperature of the NOx absorbent (19) is low while a lean mixture is being burnt, NOx oxidized by the NOx oxidizing agent (18) is absorbed by the NOx absorbent (19), while in a case where the temperature of the NOx absorbent (19) is high, NOx is oxidized by the NOx absorbent (19) so as to be absorbed by the NOx absorbent (19).