| 摘要 |
Disclosed is a NOx sensor and a method of measuring NOx capable of obtaining a large change in signal to measure a concentration of low concentration NOx in a measurement gas continuously and accurately with good response over a long period of time. A NOx sensor comprises a first internal space into which the measurement gas is introduced through a first diffusion rate-determining passage, a second internal space arranged with a NOx-reducing catalyst, into which an atmosphere is introduced through a second diffusion rate-determining passage, an electrochemical pumping cell for controlling a partial pressure of oxygen in the internal space by using a first oxygen ion-conductive solid electrolyte and electrochemical cells provided in contact therewith, a partial oxygen pressure-detecting means for detecting the partial pressure of oxygen in the internal space by using the first oxygen ion-conductive solid electrolyte and electro-chemical cells provided in contact therewith, a first electrochemical sensor cell for outputting an electromotive force corresponding to the partial pressure of oxygen in the internal space, and a voltage-detecting means for detecting the electromotive force outputted from the first electrochemical sensor cell. The NOx concentration is determined from a value of the electromotive force of the first electrochemical sensor cell detected by the voltage-detecting means.
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