| 摘要 |
PURPOSE:To increase the service life of a heater by detecting an engine temperature and an engine load when an engine is started and decreasing the repetition of electric conduction and non-electric conduction of a heater. CONSTITUTION:An O2 sensor 17 having a heater 18 is inserted and attached into an exhaust pipe 15 of an engine 1, and oxygen concentration in exhaust gas is detected and supplied to an ECU (electronic control unit) 5. The ECU 5 opens an injection valve 6, and brings an air fuel ratio of an air-fuel mixture supplied to the engine 1 to feedback control. Also, a CPU 5b derives an electric conduction/cut-off time of the heater 18 for such a air fuel ratio control, and the ECU 5 brings the heater 18 to on/off control. As for its control, when an engine load at the time of starting the engine exceeds the first load, the heater 18 is held in a non-electric conduction state, and when an engine temperature is low, the heater 18 is held in an electric conduction state for a prescribed time after the start is ended, and when said temperature is high, only when the engine load is below the second load being smaller than the first load, said heater is held in an electric conduction state. |
