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High combustion pressure in combination with high pressure gradient, as they e.g. can be evoked by high efficient combustion systems and e.g. by alternative fuels, acts as broadband excitation force which stimulates natural vibrations of piston, connecting rod and crankshaft during engine operation. Starting from the combustion chamber the assembly of piston, connecting rod and crankshaft and the main bearings represent the system of internal vibration transfer. To generate exact input and validation values for simulation models of structural dynamic and elasto-hydrodynamic coupled multi-body systems, experimental investigations are done. These are carried out on a 1.5-l inline four cylinder Euro 6 Diesel engine. The modal behaviour of the system was examined in detail in simulation and test as a basis for the investigations. In an anechoic test bench airborne and structure-borne noises and combustion pressure are measured to identify the engine´s vibrational behaviour.

The application of a turbocharger, having an electric motor/generator on the rotor was studied focusing on the electric energy recuperation on a downsized gasoline internal combustion engine (turbocharged, direct injection) using 1D-calculation approaches. Using state-of-the art optimization techniques, the settings of the valve timing was optimized to cater for a targeted pre-turbine pressure and certain level of residual gases in the combustion chamber to avoid abnormal combustion events. Subsequently, a steady-state map of the potential of electric energy recuperation was performed while considering in parallel different efficiency maps of the potential generator and a certain waste-gate actuation strategy. Moreover, the results were taken as input to a WLTP cycle simulation in order to identify any synergies with regard to fuel economy.