| 摘要 |
Provided is a urea water consumption amount diagnostic device for urea SCR which calculates an appropriate urea water consumption amount taking into account the quantization error of a urea water sensor due to replenishment, and on this basis performs a comparison with the cumulative injection amount injected by the dosing valve to detect anomalies in the dosing valve. This urea water consumption diagnostic device for urea SCR is provided with a urea water sensor (22) which detects the level of urea water inside of a urea water tank (15), a consumed amount calculation means (32) which calculates the cumulative consumed amount (D) by calculating the cumulative consumed amount (D) from the detection value inputted from the urea water sensor (22) and calculating the replenishment amount (R) from the change in level of the urea water sensor (22) after replenishment of the urea water, and an anomaly diagnostic means (33) which, when the command cumulative injection amount (P) of the urea water injected from the dosing valve (12) has become greater than or equal to a determined amount L, determines whether or not there is clogging of the urea water by comparing the cumulative consumed amount (D) and the command cumulative injection amount (P). For the changed level value of the urea water sensor when the urea water tank (15) has been replenished, the consumed amount calculation means (32) stores the level value reduced by 1 level as the replenishment amount. |
