| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust emission control device of an internal combustion engine, in which S purge processing can be performed properly by accurately controlling a temperature or an air-fuel ratio of an NOx trap catalyst during the S purge processing.SOLUTION: During S purge processing, a required time A, a rich duration time B, an excessive rich duration time C and a recovery count D are calculated, respectively, from a behavior of a downstream air-fuel ratio of an NOx trap catalyst (25). An air-fuel ratio of in-cylinder combustion is then determined based on the calculated required time A, rich duration time B, excessive rich duration time C and recovery count D, as well as a required time determination value (normal), a duration time determination value, an excessive rich determination value, a required time determination value (lean) and a recovery count determination value which are determination values. Based on a determination result, an injection amount of fuel post-injection is adjusted to provide the air-fuel ratio of in-cylinder combustion under performance matching of an engine (1). |
