| 摘要 |
PROBLEM TO BE SOLVED: To accurately estimate the concentration (an equivalent value) of an air-fuel mixture formed by mixing fuel and cylinder gas injected into a combustion chamber of an internal combustion engine, by taking into consideration influence from a squish flow. SOLUTION: This air-fuel mixture concentration estimating method determines a diffusion speed V of the air-fuel mixture forefront part from a predetermined empirical formula when assuming that there is no squish flow in the cylinder gas, and determines a squish flow speed S from a predetermined theoretical formula, and determines a speed change rateγ= (V + S)/V for expressing a degree that the squish flow has influence on an air-fuel mixture concentration equivalent value (an air excessive rate) of the air-fuel mixture forefront part from these values. The method determines an air excessive rateλof the air-fuel mixture forefront part of taking into consideration influence of the squish flow (the squish flow speed S) on the basis of a formula of correcting the empirical formula for determining the air excessive rate of the air-fuel mixture forefront part by the speed change rateγwhen assuming that there is no squish flow in the cylinder gas, to thereby accurately estimate the air excessive rate (an air-fuel mixture concentration equivalent value)λof the air-fuel mixture (the forefront part) largely influenced by the squish flow. COPYRIGHT: (C)2005,JPO&NCIPI
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