ENGINE EXHAUST PURIFICATION DEVICE

摘要

The NOx purification efficiency of a NOx reduction catalyst will be kept high even when the amount of NOx exhaust from an engine changes abruptly. The exhaust purification device purifies by reduction of NOx in exhaust using ammonia generated from an aqueous urea solution supplied by spraying. After the engine starts up, when the exhaust temperature exceeds a prescribed temperature T (S1), a quantity of the aqueous urea solution corresponding to the operating status of the engine is supplied by spraying (S3-S5). On the other hand, when the speed changes due to shifting by the driver, the operating status of the engine after the speed change is predicted (S2, S6), and before the speed change is completed a quantity of the aqueous urea solution corresponding to the predicted operating status after the speed change is supplied by spraying (S7, S8).