| abstract |
PROBLEM TO BE SOLVED: To provide an exhaust gas purifying apparatus for an internal combustion engine which can supply a reducing agent to a NOx catalyst without excess or deficiency while reflecting the consumption of the reducing agent in an upstream catalyst, and which improves exhaust gas characteristics and fuel consumption. SOLUTION: A catalyst 16, a NOx catalyst 17 provided downstream of the catalyst 16, captures NOx in an oxidizing atmosphere, and reduces and purifies NOx in a reducing atmosphere, and performs a NOx reducing operation on the NOx catalyst 17. NOx reduction control means 6, 12, 2 for supplying a reducing agent to the upstream side of the catalyst, oxygen absorption amount calculation means 2 for calculating the oxygen absorption amount S_QO 2 ST of the catalyst, and during execution of the reduction control The reducing agent consumption calculating means 2 for calculating the reducing agent consumption amount QDACO_TWC oxidized and consumed by the catalyst according to the oxygen absorption amount, and the reducing agent supply amount S_QDAL of the NOx catalyst 17 according to the reducing agent consumption amount Is provided with a reducing agent supply amount calculating means 2 and a reduction control ending means 2 for ending the reduction control based on the reducing agent supply amount. [Selection] Figure 8 |