| 摘要 |
PROBLEM TO BE SOLVED: To improve accuracy of detecting deterioration of a whole system in the system mounted with a plurality of serially connected SCR catalysts.SOLUTION: An exhaust purification system of an internal combustion engine comprises: a first SCR catalyst which is installed on an exhaust passage of the internal combustion engine and is a selective reduction type NOx catalyst to selectively reduce NOx in exhaust with ammonia as a reducing agent; a second SCR catalyst which is installed on the exhaust passage downstream of the first SCR catalyst and is the selective reduction type NOx catalyst to selectively reduce the NOx in the exhaust with the ammonia as the reducing agent; and purification rate calculation means which estimates or calculates respective NOx purification rates of the first SCR catalyst and the second SCR catalyst. The exhaust purification system of the internal combustion engine also has determination means which determines that the first SCR catalyst and the second SCR catalyst are deteriorated when an amount of the ammonia flowing out of the first SCR catalyst is equal to or larger than a threshold and the NOx purification rate of the second SCR catalyst is equal to or lower than the threshold. |
