| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine capable of determining whether or not purification performance of a HC trapping catalyst is deteriorated when rich spike is performed. <P>SOLUTION: This exhaust emission control device for the internal combustion engine is provided with a NOx trapping catalyst arranged in an exhaust system of the engine and capable of trapping nitrogen oxides (NOx) in exhaust gas and with the HC trapping catalyst arranged in the downstream side of the NOx trapping catalyst, trapping hydrocarbon (HC) discharged during cooling-down of the engine and eliminating and purifying trapping HC after the exhaust gas temperature is increased. When trapping amount of the NOx trapping catalyst is increased, the rich spike is performed such that an air fuel ratio of the exhaust gas becomes rich, and the NOx trapping catalyst eliminates and purifies the trapping NOx. The exhaust emission control device is provided with a purification performance determination means for determining whether or not the purification performance of the HC trapping catalyst is deteriorated when rich spike is performed (Step S140). <P>COPYRIGHT: (C)2005,JPO&NCIPI |
