| 摘要 |
PROBLEM TO BE SOLVED: To obtain a gas sensor in which the concentration of a gas component is controlled precisely without being affected by a heater current by feeding back and controlling the voltage across an inside pumping electrode at a main pumping cell and a reference electrode at a reference-gas introduction part and connecting an outside pumping electrode to a ground-side lead wire at a heater used to heat the main pumping cell. SOLUTION: The outside pumping electrode 64 at a main pumping cell 66 is connected to a negative-side lead wire at a heater 94, and oxygen is not moved to the side of the heater 94 from an inside pumping electrode 62. In addition, since the inside pumping electrode 62 is not connected to the lead wire at the heater 94, a phenomenon by which a resistance R at the lead wire and an electromotive force due to a heater current are superposed on a detection voltage V0 is not generated. Thereby, a control apparatus at a feedback control system 74 in which the concentration of oxygen in a gas to be measured is controlled to be constant by a pumping operation is not influenced by the leak current of the heater, by the length of the lead wire and by the heater current (heater output), and the concentration of oxygen can be controlled precisely. |
