Full Cycle Cylinder State Estimation in DI Engines with VVA

Abstract: Tougher legal demands on pollutions require a better developed understanding of the processes that take place in the cylinder. The thesis contributes with a cylinder model that uses the same set of equations for intake, compression,expansion/combustion and exhaust. The cylinder model describes the states temperature, pressure and the mass fraction of air.The model is able to simulate the gas exchange with compressible flows over the valves, it handles VVT, CRB and blowby. The combustion is modeled with asingle Vibe function that describes the heat release and the consumption of air.The model is general enough to be able to simulate both SI and CI engines. The calibrations that are needed are the discharge coefficient CD values for intake and exhaust valves, blowby, and heat release/transfer parameters. Furthermore, the engine geometry parameters have to be provided to be able to calculate the instanteneous cylinder volume. The model has shown good agreement for cylinder pressure curves with and without combustion and can handle phasingof the valve lifts. That shows that the model can handle the important casesin combustion engines. It is easy to replace sub models in the cylinder model e.g. single Vibe with double Vibe. In the model, in the cylinder is calculated and the average instantenous torque for the entire engine is calculated from thestates in one cylinder. These two calculations have shown good agreement withthe stationary measurments done in an engine test cell. The model is able to use fixed step lengths for even processor loads, the size of the step lengths are resonable for real time implementation on an ECU.