| 摘要 |
PROBLEM TO BE SOLVED: To make accurate measurement by applying a voltage to decompose a nitrogen oxide, moving the dissociated oxygen to obtain a current corresponding the nitrogen oxide concentration, and calculating the nitrogen oxide concentration obtained based on the current in response to the oxygen concentration in the detected gas. SOLUTION: The electromotive force corresponding to the oxygen concentration in the measured gas diffused and introduced into a first measurement chamber 2 is generated between the electrodes 7a, 7b of an oxygen concentration measuring cell 7. The excess oxygen is sucked, the measured gas with the constant oxygen concentration is diffused in a second measurement chamber 4, a voltage is applied to the electrodes 8a, 8b of a second oxygen ion pump cell 8, and the residual oxygen is further moved. NOx is decomposed into N2 and O2 by the catalyst action of the electrodes 8a, 8b, O2 is moved in the solid electrolyte layer of the second oxygen ion pump cell 8 as ions, and a second oxygen pump current corresponding to the decomposed nitrogen oxide concentration flows between the electrodes 8a, 8b. The nitrogen oxide concentration is calculated with the offset and gain of the nitrogen oxide concentration calculated in advance and the measured second oxygen pump current. |
