Engine control units manage various conditions in an operating engine, including fuel injection, spark ignition and valve timing, in order to achieve the goals of high performance, high fuel efficiency and low emissions. Typically, engine models are necessary for developing engine control systems. Most mean value engine models (MVEM) are based on empirical volumetric efficiency, which contributes to calculating intake air flow rate. Therefore, they are not capable of simulating changes in valve lift and valve timing, and cannot be used for a variable valve train (VVT) engine. A method of calculating intake air flow rate with variable valve lift and valve timing is needed to adapt to the demands on VVT engine models.
An engine model is proposed that focuses on a charging model, developed by using a filling-and-emptying model to simulate the air exchange in an engine, including intake- and exhaust-air flows. Flow through valves is calculated according to the pressure drop between the cylinder and manifold, and the flow area of the valve opening and its flow coefficient. An important feature of the proposed engine model is its capability for real-time simulation. The model is verified with experimental data of volumetric efficiency and indicated mean effective pressure (IMEP). Finally, a hardware-in-the-loop (HIL) simulation is performed to depict the engine model's application.