Air fuel ratio detecting arrangement and method therefor for an internal combustion engine

摘要

An air fuel ratio detecting arrangement using a diffusion suppressing type air fuel ratio sensor applicable to an air fuel ratio control unit for an internal combustion engine incorporating an atmospheric air pressure correction circuit in a signal processing and outputting device for correcting an output voltage signal processed therein based on a change in atmospheric air pressure which is detected when a predetermined operating condition of an internal combustion engine is satisfied. A secular change correction circuit included in the signal processing and outputting device detects a change in electromotive force of a concentration cell portion of the air fuel ratio sensor when a predetermined rich air fuel ratio is reached and corrects a reference voltage for the air fuel ratio sensor based on the detected change in electromotive force of the concentration cell portion in addition to an air calibration circuit.