To correct with high accuracy, the fuel injection amount of each air cylinder per air cylinder on the basis of the detected value of an oxygen concentration sensor, in an internal combustion engine such as a diesel engine.
The fuel injection amount of each air cylinder is corrected per air cylinder on the basis of the detected value of an oxygen concentration sensor 17 during a high load/low rotational period. Hereby, in an operational range having no influences of an EGR device 20 and a turbosupercharger 13 at all, and in a range having a low oxygen concentration that the detecting characteristics of the oxygen concentration sensor 17 is excellent, and besides, in a low rotational range where corresponding relation between fuel injection of each air cylinder and the detected value of the oxygen concentration sensor 17 is easily discriminated, the dispersion of the fuel injection amount of each air cylinder due to difference in individuals when manufactured (dispersion) and secular deterioration and the like are corrected with high accuracy per air cylinder by detecting the oxygen concentration of each air cylinder with high accuracy per air cylinder. As to the discrimination of each air cylinder, a specific air cylinder can be discriminated by temporarily increasing or decreasing the fuel injection amount of the specific air cylinder, and the other air cylinder is discriminated from the order of ignition on the basis of this specific air cylinder.
NAKAMURA KANEHITO
TAKEMOTO HIDETSUGU
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