| 摘要 |
PURPOSE:To detect an air fuel ratio accurately from a rich region to a lean region by supplying a current to an oxygen partial pressure control part so that the output of the oxygen partial pressure ratio detection part of an oxygen sensor attains to a command, and switching the command to positive and negative. CONSTITUTION:Exhaust gas produced by the combustion of mixed gas is admitted into a gas introduction part 15, and the ratio of the oxygen partial pressure of this gas introduction part 15 and the oxygen partial pressure of the exhaust gas is detected by an oxygen partial pressure ratio detecting part SC. The oxygen partial pressure control part PC controls the oxygen partial pressure of the gas introduction part 15 according to the amount of the supplied current. This current is supplied to the control part PC so that the output of the oxygen partial pressure ratio detection part SC attains to the preset command, which is switched to a positive and a negative command according to the output of the oxygen partial pressure detection part SC or the value of the current supplied to the control part PC. Further, the value of the current supplied to the oxygen partial pressure control part PC is detected to obtain a detection output indicating the air fuel ratio. |
