| 摘要 |
PURPOSE:To surely heat an oxygen sensor so as to hold its activated condition when necessary by a simplified device, by detecting the fully closed, that is, idling condition of a throttle valve by a throttle sensor and operating a heater for heating the oxygen sensor. CONSTITUTION:When a throttle valve 6 (not shown in fig.) in an air-flow meter 2 is not placed in its fully closed condition on the basis of a signal from a throttle sensor 18, an off-signal is output to a driving circuit 58 through an input/output port 44, stopping the electrification of a heater 22A. While in the idling condition of an engine when the throttle valve is placed in the fully closed condition, an on-signal is output to the driving circuit 58, electrifying the heater 22A. In this way, when the throttle valve 6 is fully closed, the heater 22A is operated to heat an oxygen sensor 22, preventing a decrease of its temperature in the idling condition. Then the sensor 22 can hold its activated condition, and the accurate feedback correction of air- fuel ratio can be performed on the basis of accurate detection data of oxygen concentration. |
