| 摘要 |
PROBLEM TO BE SOLVED: To accurately estimate the air-fuel ratio of each cylinder of an engine even if combustion intervals are unequal to each other or the exhaust pipe length of each cylinder is not equal to each other in the exhaust system of the engine. SOLUTION: In the engine in which the combustion intervals of each cylinder of each bank are not equal to each other or the exhaust pipe length of each cylinder is not equal to each other as in a V-type 8-cylinder engine 11, a relation between the air-fuel ratio of each cylinder and the detected values of air-fuel ratio sensors 16 is modeled for each cylinder by using model parameters different from each other for each cylinder to prepare a plurality of air-fuel ratio estimating models for each cylinder in order to estimate the air-fuel ratio of each cylinder by using the different air-fuel ratio estimating models for each cylinder. The air-fuel ratio estimating models for each cylinder is formed to use, a model input, the combination of the air-fuel ratio of a prescribed cylinder for which the air-fuel ratio is estimated with a disturbance element, and to express the disturbance element by the averaged value of the air-fuel ratios of those cylinders other than the prescribed cylinder for which the air-fuel ratio is estimated. COPYRIGHT: (C)2006,JPO&NCIPI
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