| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device of a compression ignition type internal combustion engine capable of maintaining a sufficient SOx absorbing capacity without discharging SOX and determining whether an NOx trap catalyst is deteriorated or not. <P>SOLUTION: An SOx trap catalyst 11 capable of capturing SOx contained in exhaust gases is disposed in an engine exhaust passage on the upstream side of an NOx storage catalyst 12. When it must be determined whether the SOx trap catalyst 11 is deteriorated or not, the SOx trap catalyst 11 is heated while the air-fuel ratio of the exhaust gases flowing into the SOx trap catalyst 11 is maintained lean. In this case, the concentration of NOx discharged from the SOx trap catalyst 11 is detected by an NOx concentration sensor 24. When the NOx concentration is equal to or less than a set value, the SOx trap catalyst is determined to be deteriorated. <P>COPYRIGHT: (C)2007,JPO&INPIT |
