Patent ID: 6789534
Filing Date: 2004-09-14
Classification: F02D,G05B

Abstract:
An air-fuel ratio control system for an internal combustion engine including a plurality of cylinders and an exhaust passage through which exhaust gases from the cylinders flow, the air fuel ratio control system controlling an amount of fuel to be supplied to each of the cylinders, on a cylinder-by-cylinder basis, to thereby control an air fuel ratio of a mixture supplied to each cylinder, the air-fuel ratio control system comprising:fuel amount-determining means for determining an amount of fuel to be supplied to each cylinder; correction parameter-determining means for determining a correction parameter for correcting the amount of fuel to be supplied to each cylinder; first fuel amount-correcting means for correcting the determined amount of fuel to be supplied to each cylinder, according to the determined correction parameter; air-fuel ratio parameter-detecting means for detecting an air-fuel ratio parameter indicative of an air-fuel ratio of the exhaust gases flowing through the exhaust passage; variation parameter-calculating means for calculating a variation parameter indicative of a variation in air-fuel ratio between the plurality of parameters, on a cylinder-by-cylinder basis, based on a model parameter of a model formed by modeling each cylinder and having an input of the correction parameter and an output of the air-fuel ratio parameter; identification means for identifying the model parameter of the model based on the determined correction parameter and the detected air-fuel ratio parameter; and second fuel amount-correcting means for further correcting the amount of fuel to be supplied to the plurality of cylinders on a cylinder-by-cylinder basis such that the variation parameter calculated on a cylinder-by-cylinder basis converges to a predetermined target value.