| 摘要 |
<P>PROBLEM TO BE SOLVED: To discriminate between recoverable abnormality and unrecoverable abnormality when the abnormality of a filter device is diagnosed. <P>SOLUTION: An exhaust emission control system includes: a urea water tank 21 for storing urea water; a urea water adding valve 15 connected to the urea water tank 21 through a urea water supply pipe 22 and adding the urea water in the urea water tank 21 into an exhaust pipe 11; a urea water pump 23 arranged in the urea water supply pipe 22 and feeding the urea water to the urea water adding valve 15; and a urea water filter 25 provided in the urea water supply pipe 22. In this system, an ECU 40 detects a pressure difference between the upstream side of the urea water filter 25 and the downstream side thereof, and also diagnoses the abnormality of the urea water filter 25 based on a change on a depressurization side in the detected pressure difference during operation of the urea water pump 23. <P>COPYRIGHT: (C)2010,JPO&INPIT |
