| 摘要 |
PURPOSE:To control combustion in an engine on the basis of estimated result obtained by eliminating influence of an air fuel ratio change and remaining gas, and estimating NOx discharging condition with high accuracy. CONSTITUTION:A combustion temperature T is calculated on the basis of an intake air amount, an internal cylinder pressure, and the capacity of a combustion chamber. The maximum temperature Tmax in a combustion temperature T calculated in a range from a compression top dead point to ATDC 60 deg. is retrieved (step 12). Correction for eliminating influence of remaining gas is carried out to the combustion temperature Tmax on the basis of an engine output torque Trq and a rotational speed Ne (step 15). A correlation formula for converting the combustion temperature Tmax into NOx concentration is selected on the basis of an air fuel ratio (step 17). The combustion temperature Tmax is converted into NOx concentration by using the selected correlation formula (step 18), and an ignition timing is corrected on the basis of comparison between the converted NOx concentration and a prescribed value (step 19 to 23).
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