Exhaust purification device of internal combustion engine

摘要

PCT No. PCT/JP92/01279 Sec. 371 Date Jun. 14, 1993 Sec. 102(e) Date Jun. 14, 1993 PCT Filed Oct. 2, 1992 PCT Pub. No. WO93/07363 PCT Pub. Date Apr. 15, 1993.An NOx absorbent (18) is disposed in an exhaust passage of an internal combustion engine and the exhaust gas is constantly made to circulate through the NOx absorbent (18) during the operation of the engine. The NOx absorbent (18) absorbs the NOx when the air-fuel ratio of the exhaust gas flowing into the NOx absorbent (18) is lean and releases the absorbed NOx when the air-fuel ratio of the exhaust gas flowing into the NOx absorbent (18) becomes the stoichiometric air-fuel ratio or rich. In the majority of the engine operation region, the lean air-fuel mixture is burned in the combustion chamber (3), and the NOx generated at this time is absorbed into the NOx absorbent (18). The air-fuel ratio of the exhaust gas flowing into the NOx absorbent (18) is periodically made the stoichiometric air-fuel ratio or rich, and the NOx absorbed in the NOx absorbent (18) is released, and simultaneously reduced.