| 摘要 |
PROBLEM TO BE SOLVED: To carry out a sulfur poisoning restoring process of a NOx storage reduction catalyst having an oxide storage function without deteriorating a catalyst function.SOLUTION: The NOx storage reduction catalyst 22 is arranged in an engine exhaust passage, and a reducing agent supplying means 24 is arranged in the engine exhaust passage 21 upstream of the NOx storage reduction catalyst 22, The NOx storage reduction catalyst 22 further includes the oxide storage function. The exhaust emission control device of an internal combustion engine includes a sulfur poisoning restoring processing means for carrying out the sulfur poisoning restoring process when SOx, which is stored in the NOx storage reduction catalyst, is to be discharged. When the sulfur poisoning restoring processing means is to execute the sulfur poisoning restoring process, a reducing agent is supplied from the reducing agent supplying means during a lean combustion period for making an air-fuel ratio of gas in a cylinder lean, and control for making the air-fuel ratio of the gas in the cylinder rich is conducted after the lean combustion period passes. The lean combustion period is set longer, the smaller an exhaust gas amount is. |
