| 摘要 |
PROBLEM TO BE SOLVED: To effectively prevent combustion of an engine from becoming unstable when starting and after finishing catalyst regeneration.SOLUTION: An exhaust emission control system comprises an NOx reduction type catalyst 32 provided in an exhaust passage of an internal combustion engine 10, an intake air quantity sensor 40 and a control unitt 50 for executing regeneration processing of the NOx reduction type catalyst 32 by switching exhaust gas to a rich state from a lean state by simultaneously using air system control for reducing an intake air quantity and injection system control for increasing a fuel injection quantity, and the control unit 50 executes first follow-up control for changing the fuel injection timing of the internal combustion engine in response to a detection value of the intake air quantity sensor 40 in a switching period to the rich state from the lean state, and stops the first follow-up control by advancing the fuel injection timing of the internal combustion engine 10 to the target fuel injection timing corresponding to the rich state when the intake air quantity detected in the switching period is separated by a predetermined threshold value or more from a target intake air quantity in the switching period.SELECTED DRAWING: Figure 1 |
