Method and system for calculating Atkinson cycle intake flowrate of internal combustion engine

A system for calculating Atkinson cycle intake flowrate of an internal combustion engine, characterized in that it comprises:

• an intake stopping point determination module, which is employed to determine an intake stopping point and an engine crank angle corresponding to a piston position of the internal combustion engine at the intake stopping point;
• a mass and partial pressure determination module, which is employed to calculate mass and partial pressure of an exhaust gas as well as mass and partial pressure of a fresh gas within a cylinder from the engine crank angle when the piston position of the internal combustion engine is at the intake stopping point;
• a mass ratio determination module, which is employed to obtain a mass ratio of a quantity of gas pushed out of the cylinder by a piston to a total quantity of gas within the cylinder at the intake stopping point during a period of time starting from the intake stopping point until intake valve closure according to the mass and the partial pressure of the exhaust gas as well as the mass and the partial pressure of the fresh gas within the cylinder calculated;
• and
• an intake flowrate acquisition module, which is employed to calculate intake flowrate of the fresh gas within the cylinder at the intake valve closure from the mass ratio obtained.