| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an NOx sensor diagnosing device capable of diagnosing the validity of an NOx sensor in consideration of an environmental condition and preventing a wrong diagnosis, and to provide an SCR system with the same. <P>SOLUTION: The NOx sensor diagnosing device is provided in an exhaust pipe 102 of an engine E and diagnoses an NOx sensor 110 for detecting the NOx concentration in exhaust gas, and is provided with a calculated value calculating unit 2 for finding a calculated value of the NOx concentration in the exhaust gas on the basis of the operating state of the engine E, an abnormal condition determining unit 3 for determining that the NOx sensor 110 is abnormal when the difference between the calculated value of the NOx concentration found by the calculated value calculating unit 2 and the detected value of the NOx concentration detected by the NOx sensor 110 exceeds a determination threshold, and a determination threshold setting unit 4 for setting the determination threshold on the basis of the temperature of cooling water for cooling the engine E, atmospheric pressure, and ambient temperature. <P>COPYRIGHT: (C)2012,JPO&INPIT |
