CLOSED-LOOP EMISSION CONTROL APPARATUS FOR INTERNAL COMBUSTION ENGINE WITH A CIRCUIT FOR GENERATING OFFSET VOLTAGE THAT CANCELS ERROR INTRODUCED DURING USE

摘要

A closed-loop emission control apparatus for internal combustion engines includes an exhaust composition sensor disposed at the upstream side of a catalytic converter which converts the noxious exhaust components into harmless products at the highest efficiency when the air-fuel ratio is controlled at a value in the vicinity of stoichiometry in accordance with a control signal derived from the sensed concentration of the exhaust composition. The output from the exhaust composition sensor is utilized to generate an offset voltage by averaging the instantaneous values of the sensed concentration, the offset voltage being combined with the control signal to cancel an error introduced thereinto during use of the apparatus.