| 摘要 |
PROBLEM TO BE SOLVED: To provide a urea water consumption amount diagnosis device for urea SCR which can detect an abnormality of a dosing valve or the like by obtaining a proper urea water consumption amount by taking into consideration a quantization error of a urea water sensor caused by replenishment and by comparing the urea water consumption amount with an integrated spray amount which is sprayed by the dosing valve on the basis of the urea water consumption amount.SOLUTION: A urea water consumption amount diagnosis device for urea SCR comprises: a urea water sensor 22 which detects a level of urea water in a urea water tank 15; consumption amount calculation means 32 which calculates an integrated consumption amount D from a detection value inputted from the urea water sensor 22, calculates a replenishment amount R from a change of the level of the urea water sensor 22 after the replenishment of urea water, and calculates the integrated consumption amount D; and abnormality diagnosis means 33 which determines the presence or absence of the clogging of the urea water by comparing the integrate consumption amount D and an integrated command spray amount P when the integrated command spray amount P of the urea water sprayed from a dosing valve 12 reaches a determination amount L or larger. The consumption calculation means 32 stores, as the replenishment amount, a level value which is subtracted by one level with respect to the change of the level of the urea water sensor when the replenishment is performed. |
