| 摘要 |
PROBLEM TO BE SOLVED: To provide an SCR system capable of discriminating whether the adhesion of a float results from an urea water level sensor or an urea water injector.SOLUTION: An exhaust emission control device 200 comprising: an SCR catalyst 33, NOx sensors 46, 47; an injection injector 55; and a tank 50, comprises: a level sensor 120 which is provided in the tank 50 and detects a liquid level height of a liquid reducer within the tank 50; a determination unit 71 which calculates a change in the liquid level height detected by the level sensor 120 and determining whether the change in the liquid level height is normal or abnormal; a calculation unit 72 which calculates a NOx purification rate on the basis of detection values of the NOx sensors 46, 47; and a discrimination unit 73 which discriminates whether the level sensor 120 is abnormal or the injection injector 55 is abnormal on the basis of the liquid level height and the NOx purification rate.SELECTED DRAWING: Figure 2 |
