| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine, certainly raising the catalyst temperature of a NOx storage reduction catalyst to desorption temperature of a sulfur compound when performing sulfur poisoning recovery control. <P>SOLUTION: In this exhaust emission control device, as the sulfur poisoning recovery control over the NOx storage reduction catalyst 10, temperature rise control is performed so that exhaust gas of a rich air-fuel ratio is discharged from first cylinder groups #1, #4, exhaust gas of a lean air-fuel ratio is discharged from second cylinder groups #2, #3, exhaust gas of the rich air-fuel ratio and exhaust gas of the lean air-fuel ratio are reacted in the NOx storage reduction catalyst after being mixed in one common exhaust pipe, and the temperature of the Nox storage reduction catalyst is raised to the desorption temperature of the sulfur compound with the sulfur compound desorbed from the NOx storage reduction catalyst, by heat of reaction obtained according to a difference between the air fuel ratios of exhaust gas. When the temperature of the Nox storage reduction catalyst is determined not be raised to the desorption temperature of the sulfur compound within a predetermined time, air-fuel ratio difference increasing control is performed for increasing the difference between the air-fuel ratio. <P>COPYRIGHT: (C)2009,JPO&INPIT |
