| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technology for accurately determining plugging of an exhaust purifying catalyst based on the output of an air-fuel ratio sensor in an exhaust emission control device for an internal combustion engine supplying unburnt fuel to the exhaust purifying catalyst by post-injection, addition of exhaust system fuel, or the like. <P>SOLUTION: The exhaust emission control device for the internal combustion engine is provided with a downstream side A/F sensor provided in an exhaust passage downstream of the exhaust purifying catalyst, and a fuel addition valve supplying fuel in the internal combustion engine to a particulate filter to which a storage reduction NOx catalyst is held. The exhaust emission control device determines plugging of the particulate filter on condition that the difference between reference output A/Fdsb and the output A/Fd of the downstream side A/F sensor when fuel is added in the high temperature state of the particulate filter, and the difference between reference output A/Fdsb and the output A/Fd of a downstream side A/F sensor when fuel is added in the low temperature state of the particulate filter, are both the specified quantity or more. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
