| 摘要 |
PROBLEM TO BE SOLVED: To improve the purifying rate of a NOX selecting/deoxidizing catalyst, by executing a first auxiliary injection as an auxiliary injection in an expansion stroke so as to generate an HC thermal decomposition, and executing a second auxiliary injection in an expansion stroke or an exhaust stroke after the first auxiliary injection so as to increase an HC amount in exhaust gas. SOLUTION: When an engine is operated, the temperature of an NOX selecting/ deoxidizing catalyst 10 is detected by a temperature sensor 12 in an ECU 40, and it is discriminated whether or not the temperature of the NOX selecting/deoxidizing catalyst 10 is at the optimal temperature To or more, and when judged YES, fuel injection control is executed. Namely, main injection A is executed from a fuel injection valve 6 to the inside of a cylinder just after a top dead center(TDC) that a compression stroke is completed, and auxiliary injection C (a second auxiliary injection) is executed in the latter period of the subsequent expansion stroke. While, in the case that the catalyst temperature is at To or below, the main injection A is executed just after TDC that the compression stroke is completed, and after that, auxiliary injection B (a first auxiliary injection) is executed in the middle period of the expansion stroke, and next, the second auxiliary injection C is executed in the latter period of the expansion stroke. |
