Abnormality diagnosis apparatus for a gas concentration measuring apparatus and abnormality diagnosis method for a gas concentration measuring device

摘要

PROBLEM TO BE SOLVED: To identify the details and occurrence positions of abnormality, without making a sensor element damaged, when an abnormality occurs in a gas concentration measuring device employing a gas sensor such as a whole region air-fuel ratio sensor, an NOx sensor or the like.;SOLUTION: At the voltage value of a connection point connecting the sensor element 10 to a sensor element control circuit 50 becoming an abnormal voltage value being previously set, when the gas concentration measuring device 1 is in its operation state, the sensor element control circuit 50 is shut off from each connection point. Accordingly, abnormal current flowing in the sensor element 10 is blocked at an abnormality occurrence timing, thereby preventing the sensor element 10 from damaging. Then, the sensor element control circuit 50 supplies the sensor element 10 with current, whose level will not cause the sensor element 10 to damage, and detects voltage values of respective connection points. The details and occurrence locations of the abnormality in the sensor element 10 are identified, based on respective terminal voltage values detected at the connection points.;COPYRIGHT: (C)2006,JPO&NCIPI