Author: Dr. Stefan Lauer
Friedrich Graf (Dipl.-Ing.), Continental, Regensburg;
Dipl.-Ing. Moritz Springer, Ford Werke GmbH, Cologne;
Dipl.-Ing. (FH) Stefan Wechler, Schaeffler Technologies AG & Co.KG, Herzogenaurach
The presented propulsion concept targets the market between the 48 volt starter generator systems and high voltage hybrid systems. The demonstrator vehicle has an attractive cost/benefit ratio and increases its significance by the usage of a manual gearbox. In order to enable both CO2 savings and good drivability, in a holistic approach, a high power density gasoline engine has been combined with a 48 volt P2-hybrid system. The low end torque of the internal combustion engine is enhanced by an electric torque support allowing for an effective downspeeding. The central component of the P2 system is a hybrid module that provides an increased regeneration potential and an optimized operating strategy which enables a decrease in CO2 emission. The P2 system is in particular characterized by an axial-parallel arranged e-machine that is connected with the powertrain and an air conditioning compressor via a belt drive. Other ingredients include an automated drive clutch “K1” and another clutch “K0” for the decoupling of the combustion engine from the powertrain. The opportunity to offer an electric air conditioning without additional costs and moreover purely electric driving at low speeds are two of the most attractive functions of this P2 hybrid electric vehicle. With the e-drive option in particular the basis for automated parking is set also with manual transmissions. Finally the possibility of a comfortable engine start with the 48 volt e-machine, similar to a starter generator system, is maintained. Various maneuvers are considered and compared in a standard drive cycle with regards to functionality and drivability. Especially the experience of electric driving is assessed for this 48 volt P2 hybrid vehicle. Crucial for the success of this new concept is a completely new 48 volt P2-focused drive strategy and an energy management system that provides the foundation for the discussed 48 volt based functionalities.