Patent ID: 7905135

Claim:
A cylinder charged air quantity calculating apparatus for an internal combustion engine which calculates a cylinder charged air quantity by using an equation of an intake system model including a throttle flow rate parameter which represents a flow rate parameter depending on a throttle opening degree, the cylinder charged air quantity calculating apparatus comprising: storage means for staring a map defining a relationship between a throttle opening degree and a throttle flow rate parameter; learning means for determining whether a predetermined learning execution condition is fulfilled and for learning, when the predetermined learning execution condition is fulfilled, a learning correction amount with respect to a map value based on a deviation between an actual value of the throttle flow rate parameter calculated according to a present throttle opening degree by using the equation of the intake system model and the map value of the throttle flow rate parameter read from the storage means; correcting means for correcting the map value of the throttle flow rate parameter corresponding to a present throttle opening degree read from the storage means during an operating state of the internal combustion engine by using the learning correction amount; and cylinder charged air quantity calculating means for calculating a cylinder charged air quantity by using the map value of the throttle flow rate parameter corrected by the correcting means during an operation of the internal combustion engine, wherein the internal combustion engine is provided with a supercharger; and the predetermined learning execution condition is at least: (1) the engine is in a steady operation state in which a change in an intake air quantity is small; (2) the engine is in a low air quantity region in which the intake air quantity is less than or equal to a predetermined value; and (3) a pressure ratio Pm/Pthrup of the throttle downstream pressure Pm to the throttle valve upstream pressure Pthrup is less than or equal to a predetermined value.