AIR-FUEL RATIO DETECTOR

摘要

PURPOSE:To make possible the simple execution of air-fuel ratio control in the entire air-fuel ratio range with good accuracy by obtaining the detection signal corresponding to the air-fuel ratio in the entire region from the lean to rich region of the air-fuel ratio and using the detection signal thereof. CONSTITUTION:A detecting element part 2 consists of an oxygen pump element 7 and an oxygen concn. cell element 11 formed with porous electrodes 5 and 6, 9 and 10 respectively on both side faces of solid electrolytes 4, 8 having oxygen ion conductivity. An air-fuel ratio signal detecting circuit 3 controls the voltage generated from the element 11 or the current flowing to the element 7 and outputs the air-fuel ratio signal corresponding to the oxygen concn. in the exhaust gas. An air chamber (b) is provided to the element part 2 in such a manner that the electrode 10 of the element 11 contacts with the atm. and a means for supplying the constant current consisting of an operational amplifier OP1 and a transistor TR1 is provided to the circuit 3 in such a manner that the oxygen in atm. is poured into a diffusion chamber (a) (a space between the element 7 and 11) at a specified amt. by which the current I1 to be passed to the element 1 is made constant. The continuous air-fuel ratio signal from the lean to rich region is thus obtd.