Urea spray selective catalytic reduction control system

摘要

A urea spray selective catalytic reduction (“SCR”) control system includes an SCR catalyst provided in a discharge pipe of an engine, a dosing valve for injecting urea water at an upstream side of the SCR catalyst, and NOx sensors, wherein the system controls injection of the urea water from the dosing valve. The system includes a plurality of NOx model maps corresponding to an atmospheric pressure condition, an outdoor air temperature, and an engine water temperature, and determines an amount of NOx from each NOx model map on a basis of detection values of an atmospheric pressure detector, an outdoor air temperature detector, and an engine water temperature detector, and controls an amount of injection of the urea water from the dosing valve on a basis of the amount of NOx thus determined.

主权项

1. A urea spray selective catalytic reduction control system comprising:
a selective catalytic reduction catalyst in a discharge pipe of an engine, a dosing valve for injecting urea water at an upstream side of the selective catalytic reduction catalyst, and an electronic controller which is configured to control injection of the urea water from the dosing valve by— referring to a plurality of NOx model maps which correspond to an atmospheric pressure condition, an outdoor air temperature and an engine water temperature, determining an amount of NOx on a basis of detection values of an atmospheric pressure detector, an outdoor air temperature detector, and an engine water temperature detector, and controlling the amount of the injection of the urea water from the dosing valve on a basis of the amount of NOx thus determined, wherein each of the plurality of NOx model maps is stored to the electronic controller, which includes a base map including a plurality of outdoor air temperature-dependent NOx maps in which the amount of NOx is set in accordance with an engine rotation, and an amount of injection commanded on the basis of an outdoor air temperature under an atmospheric pressure condition at a ground level is provided, and an outdoor air temperature map selection factor for selecting an outdoor air temperature-dependent NOx map from the outdoor air temperature-dependent NOx maps using an actual outdoor air temperature, and interpolating the NOx value using the outdoor air temperature-dependent NOx map, and a correction map for correcting the NOx value given by the base map under an atmospheric pressure condition at a height, and further includes an engine water temperature correction map for correcting, with an engine water temperature, the NOx value determined by an atmospheric pressure condition and an outdoor air temperature condition.