Intake air quantity calculating apparatus for an internal combustion engine with a variable valve timing control mechanism

Abstract

An intake air quantity calculating apparatus for an internal combustion engine equipped with a variable valve timing control mechanism is provided. By the apparatus, an intake pipe pressure is detected or estimated. An intake air pulsation rate is determined on the basis of the detected or estimated intake pipe pressure and engine speed. An air flow error correction term basic value is determined on the basis of a throttle valve opening degree and engine speed. The air flow error correction term basic value is corrected on the basis of the intake air pulsation rate, whereby to determine an air flow error correction term for correcting an error in detection of an intake air quantity by an air flow meter. By the air flow error correction term, an intake air quantity detected by an air flow meter is corrected, whereby it becomes possible to improve the accuracy in calculation of the intake air quantity. In case the intake pipe pressure is to be estimated, an intake pipe pressure basic value is determined from the throttle valve opening degree and the engine speed. The intake pipe pressure basic value is corrected on the basis of a closing timing of an intake valve, whereby to estimate the intake pipe pressure. A method of calculating an intake air quantity of the engine through correction of an intake air quantity detected by an air flow meter is also provided.