| 摘要 |
PROBLEM TO BE SOLVED: To enable control of an air ratio and detection of the concentration of an unburned component in exhaust by a single oxygen sensor, by checking the concentration of the unburned component in the exhaust of combustion of a burner on the basis of an output current of the oxygen sensor having a solid electrolyte, in a state wherein a voltage for detecting an unburned state is applied on the oxygen sensor. SOLUTION: When a voltage is applied on a solid electrolyte 21 and a current is made to flow forcedly under the condition of a temperature of a prescribed value (e.g. 650 deg.C) or above in a lean area of fuel gas, migration of O<2-> ions from a cathode to the anode side through the solid electrolyte 21 occurs and a current value is detected by a current detector 3. An applied voltage switchover means 2 switches an applied voltage of an oxygen sensor 20 having the solid electrolyte 21 between a voltage for controlling an air ratio and a voltage for detecting an unburned state in the vicinity of 0V. In the state wherein the applied voltage is the voltage for detecting the unburned state, the concentration of an unburned component in exhaust is checked on the basis of the amplitude of a minus output current of the oxygen sensor. |
