| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a NOx detector for suppressing the lowering of NOx detection accuracy even if the concentration of oxygen in measuring object gas varies. <P>SOLUTION: This NOx detector 1 starts a NOx pumping motion (pumping-out motion) from a gas detection chamber 19 (S470) when the electromotive force Vs of a gas detection cell 30 comes to an oxygen criterion value (positive determination at S450). In short, as to this NOx detector 1, oxygen concentration in the detection chamber 19 becomes a constant concentration at the time point when NOx discharge by a gas pump cell 11 is started even if oxygen concentration in exhaust gas varies. The NOx detector 1 can accurately detect NOx concentration even if the oxygen concentration in exhaust gas varies, since the NOx detector 1 thus starts NOx discharge under the condition that the oxygen concentration in the detection chamber 19 becomes a constant concentration and detects NOx concentration based on the time (first elapsed time T<SB>LR</SB>) required for the NOx discharge. <P>COPYRIGHT: (C)2007,JPO&INPIT |
