Air-to-fuel ratio detector for engines

摘要

An air-to-fuel ratio detector for detecting the air-to-fuel ratio of the combustible mixture supplied to an engine on the basis of the concentration of oxygen gas in the exhaust gas of the engine, comprising an air-to-fuel ratio sensor provided to detect the oxygen gas concentration in the exhaust gas and consisting of an oxygen pump and an oxygen sensor which are disposed with a minute gap therebetween, and changeover means for simultaneously changing the direction of the pump current supplied to the oxygen pump and the polarity of the detection output signal given by the oxygen sensor; thereby capable of obtaining an air-to-fuel ratio detection signal when the operating air-to-fuel ratio is either in the rich air-to-fuel region or in the lean air-to-fuel region with respect to the stoichiometric air-to-fuel ratio.