| 摘要 |
PROBLEM TO BE SOLVED: To provide an oxygen sensor controller which can accurately detect impedance of an oxygen sensor and perform precise air-fuel ratio control by the oxygen sensor at the same time with a simple configuration, and which can further contribute to maintaining a high purification rate for each gas component of an exhaust gas.SOLUTION: Oxygen sensor controllers 100 and 110 each comprise: a shunt resistor Rs connected in series to an oxygen sensor 10; an impedance measurement switching circuit 20 connected to a high potential side of the shunt resistor Rs and switching current flowing through the shunt resistor Rs between an impedance detection period and an air-fuel ratio control period; and a constant current circuit 40 setting current to be drawn from or to be flown to the oxygen sensor 10 at a predetermined value, in order to control the air-fuel ratio at which electromotive force of the oxygen sensor 10 suddenly changes by transition to a rich or lean side. The constant current circuit 40 is connected between the high potential side of the oxygen sensor 10 and the impedance measurement switching circuit 20. |
