AIR-FUEL RATIO CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an air-fuel ratio control device performing air-fuel ratio feedback control based on at least a deviation integral value updated by integration of deviations between output values of an air-fuel sensor downstream of a catalyst and a target value corresponding to a target air-fuel ratio and capable of inhibiting erroneous learning of the deviation integral value toward a rich side even when executing learning of the deviation integral value after return from fuel-cut control (FC).

SOLUTION: A feedback correction value is calculated through PID processing about [a deviation between the output value of the air-fuel sensor downstream of the catalyst and an output value Voxsref (constant) corresponding to the target air-fuel ratio] and an air-fuel ratio is controlled to agree with the target air-fuel ratio (= theoretical air-fuel ratio). Only in a predetermined period (flag ORE =1) after the time of FC return, an I processing in the PID processing is exerted with use of [the deviation between the output value of the air-fuel ratio sensor and the target value Voxsrefi (< Voxsref) corresponding to an air-fuel ratio more lean than the target air-fuel ratio] in place of [the deviation between the output value of the air-fuel ratio sensor and Voxsref].

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