O2 sensor, apparatus for and method of controlling air-fuel ratio, and recording medium storing air-fuel ratio control program

摘要

A system controls the air-fuel ratio in an exhaust gas supplied from an internal combustion engine to a catalytic converter in order to keep an output voltage Vout of an O2 sensor disposed downstream of the catalytic converter at a predetermined target value Vop. In the system, the temperature of an active element of the O2 sensor is controlled at a predetermined temperature such that the output voltage of the O2 sensor at an inflection point of output characteristics thereof is substantially the same as the target value Vop.