| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a device for determining an abnormal section of an exhaust emission control system capable of determining even abnormality of each element constructing the exhaust emission control system. <P>SOLUTION: This device for determining the abnormal section of the exhaust emission control system includes a selective reduction type NOx catalyst 34 provided in an exhaust gas passage of an internal combustion engine, an NH<SB>3</SB>oxidation catalyst 36 and an urea water supply means 40 at a downstream thereof. The device is provided with a NOx sensor 52 disposed at a downstream of the NH<SB>3</SB>oxidation catalyst, a NOx concentration increase means increasing NOx concentration of exhaust gas by predetermined quantity during an abnormality determination mode, a first output value change detection means detecting change of output value of the NOx sensor when the NOx concentration is increased by predetermined quantity, an urea water supply quantity increase control means controlling predetermined quantity increase of the urea water supply quantity, a second output value change detection means detecting change of output value of the NOx sensor when urea water supply quantity is controlled to be increased by predetermined quantity, and a first determination means determining if at least the selective reduction type NOx catalyst and the NH<SB>3</SB>oxidation catalyst is normal or abnormal based on change of output value of the NOx sensor. <P>COPYRIGHT: (C)2009,JPO&INPIT |
