| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a NOx sensor diagnostic device and an exhaust emission control system using the same accurately diagnosing abnormality of the NOx sensor with reducing fluctuation of an engine operation state due to abnormality diagnosis as much as possible. <P>SOLUTION: The NOx sensor diagnostic device calculates change injection quantity (DELQFIN) reducing injection quantity command value from target injection quantity command values 200, 210 based on the engine operation state. The NOx sensor diagnostic device detects an average value (RENOxAVE) of concentration of NOx emitted from an engine before changing the injection quantity command value by the change injection quantity (DELQFIN), and the minimum value (RENOx1) of NOx concentration dropped by changing the injection quantity command value by the change injection quantity (DELQFIN) from output values of the NOx sensor. The NOx sensor diagnostic device diagnoses that the NOx sensor is abnormal if difference which is change quantity of the average value (RENOxAVE) of the concentration of NOx and the minimum value (RENOx1) of the concentration of NOx slips from a designated range. <P>COPYRIGHT: (C)2009,JPO&INPIT |
