| 摘要 |
Provided is a urea spray SCR control system with which the amount of urea sprayed can be controlled appropriately in accordance with the discharged amount of engine-out NOx during the period when preliminary heating control is performed. This urea spray SCR control system, which is equipped with an SCR catalyst (23) provided on the exhaust pipe (14) of an engine (10), a dosing valve (41) that sprays aqueous urea water upstream from the SCR catalyst (23), and NOx sensors (46, 47) that measure the amount of NOx in the exhaust gas, and which controls the spraying of the urea water from the dosing valve (41), is further equipped with multiple NOx model maps (60) corresponding to the atmospheric pressure conditions, the outside air temperature, and the engine water temperature. The NOx amount is determined from each NOx model map (60) on the basis of the detection values from the atmospheric pressure sensor, the outside air temperature sensor, and the engine water temperature sensor, and the amount of urea water sprayed from the dosing valve (41) is controlled on the basis of the NOx amount that has been determined. |
