| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a gas concentration detection apparatus for detecting the concentration of a specific gas in the exhaust gas discharged from an engine, and to determine the deterioration of the gas concentration detector at an early stage, with high accuracy. <P>SOLUTION: In a NOx concentration detector for detecting the concentration of NOx by a Nox sensor cell 4, after excess oxygen has been discharged by an oxygen pump cell 2, it is determined whether a Nox sensor 1 is activated, that is, whether an inflection point appears in the output of the NOx sensor cell of the NOx sensor 1 (step 200). When the NOx sensor 1 has yet not been activated, the output rising speed Vu(t) of the output N of the NOx sensor cell in the rising process of the output of the NOx sensor cell is acquired (steps 202-208). It is determined whether the output rising speed Vu(t) is smaller than a predetermined reference value Vth1 (step 210); and when the establishment of Vu(t)<Vth1 is recognized, the deterioration of the NOx sensor cell 4 is determined (step 212). <P>COPYRIGHT: (C)2010,JPO&INPIT |
