GAS CONCENTRATION DETECTING DEVICE

摘要

A gas concentration detecting apparatus comprises a gas concentration detecting device and an electron control unit. The gas concentration detecting device includes a first electrochemical cell and a second electrochemical cell. The electron control unit detects concentration of sulfur oxide included in a gas to be detected based on a first detected value corresponding to a current flowing in the first electrochemical cell obtained when a first removing voltage is applied to the second electrochemical cell and a measuring voltage is applied to the first electrochemical cell. The first removing voltage is a voltage that the second electrochemical cell initiates decomposition of nitrogen oxide or a higher voltage; a voltage equal to or higher than the lowest limit of a voltage range showing the limit current properties of nitrogen oxide in the second electrochemical cell; and a voltage lower than a voltage initiating decomposition of sulfur oxide. Provided in the present invention is a gas concentration detecting apparatus capable of accurately detecting concentration of sulfur oxide included in exhaust as a gas to be detected by using a limit current-type gas sensor.