| 摘要 |
PURPOSE:To protect an O2 sensor element and a heater, also to reduce the power consumption of the heater, and to stabilize the temperature of the O2 sensor element by conducting and controlling a heater in accordance with the number of times of a rich/lean inversion at every prescribed time of the output of the O2 sensor. CONSTITUTION:The O2 sensor 9 is provided on an exhaust passage 8. The output of this sensor 9 is supplied to an input/output interface 102 through the first comparing circuit 110 of a control circuit 10. Also, the sensor 9 contains a heater 9a, and the electric conduction control of the heater 9a is executed by the second comparing circuit 109 and the driving circuit 111 of a controlling circuit 10. Also, in the circuit 10, a down counter 106, an FF 107, and a driving circuit 108 control a fuel jet valve 7. The jet valve 7 is energized by a fuel jet quantity, and the fuel of quantity corresponding to the fuel jet quantity is fed into the combustion chamber of an engine body 1. In this way, when the number of times of a rich/lean inversion of an output per a prescribed time of the sensor 9 is smaller than a prescribed value, the heater is conducted electrically, and when it is larger, the electric conduction to the heater is stopped, therefore, the heating of the sensor caused by the heater when it is not required is prevented.
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