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.

The ability to control engine valve timing has the potential to alter the engine performance over the entire operating range. The outcome of valve timing technology enables the possibility to increase efficiency, lowering emissions, increase engine torque, etc. One of the simplest ways to obtain a variable valve timing is to use cam phasers. The dynamics of a hydraulic cam phaser has been studied, three concepts with the purpose to control such an element has been developed using simulation driven product development. Focus have been on robustness, simplicity and implementation. A final concept using on/off solenoids to control a torque driven cam phaser has been designed and simulated in GT-SUITE which validated its performance and functionality. A dynamic model was built in Simulink which simulated the behaviour of the cam phaser and provided tools for optimizing the rotor design. By combining the knowledge of mechanical- and control engineering at Scania, the development process of such machine elements was effective. The outcome of this thesis has given a new perspective in understanding these components and their potentials.