| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine capable of completing sulfur removing control at appropriate timing when a reducer having a quantity necessary for removing a sulfur component is supplied to a NOx catalyst without an excess and shortage according to an actual sulfur poisoning quantity adhering to the NOx catalyst irrespective of a technique for controlling exhaust gas to a reduction atmosphere. <P>SOLUTION: The exhaust emission control device for the internal combustion engine executes sulfur component removing control for removing the sulfur component adhered to the NOx catalyst 7 by controlling exhaust gas to a reduction atmosphere (step 5). An air fuel ratio delay time TMAFDLY indicating an oxygen storage capacity of the NOx catalyst 7 is calculated based on a downstream side exhaust gas air fuel ratio AEEX2 downstream of the NOx catalyst 7 which is detected during the sulfur removing control (step 37), a sulfur poisoning quantity is calculated based on the air fuel ratio delay time TMAFDLY (step 38, Fig.7), and the completion timing of sulfur removing control is determined according to the sulfur poisoning quantity QS (step 10, 11). <P>COPYRIGHT: (C)2010,JPO&INPIT |
