EXHAUST EMISSION CONTROL SYSTEM

摘要

PROBLEM TO BE SOLVED: To prevent deterioration of drivability due to MAF follow-up control.SOLUTION: An exhaust emission control system includes: an NOx reduction type catalyst 32; an intake air amount sensor 40 for acquiring intake air amount; catalyst regeneration control sections 60, 70 for performing catalyst regeneration processing for recovering purification capacity of the NOx reduction type catalyst 32 by switching exhaust gas to a rich state by using both of air system control for reducing intake air amount and injection system control for increasing fuel injection amount; a follow-up control section 80 for performing follow-up control for changing at least one of fuel injection timing and fuel injection amount of an internal combustion engine 10 in accordance with the intake air amount acquired by the intake air amount sensor 40 for a switching period from a lean state to the rich state and a switching period from the rich state to the lean state; and a prohibition section 81 for prohibiting the performance of the follow-up control in the case where the internal combustion engine 10 is in a motoring state when the follow-up control is performed.SELECTED DRAWING: Figure 1