The main objective of active downsizing is to increase the power train efficiency. In order to consistently enhance an approach of active downsizing, it is inevitable to disable and additionally to disengage part of the overall engine displacement volume. The disengagement avoids the friction loss of the piston group as well as its crank- and valve-train section. Therefore, this beneficial approach, the Split-Crankshaft Engine (SCE) is currently under development at the Chair of Internal Combustion Engines in cooperation with the Gear Research Centre (FZG), at the Technical University of Munich.
The SCE concept consists of two partial internal combustion engines, which are arranged inline. The Primary Engine (PE) is permanently running while the Secondary Engine (SE) can be switched on and off load-dependently during driving operation. Within the switching process, the electromechanically actuated Split-Clutch Unit (SCU) realizes the run-up of the SE as well as the angular synchronization of both partial engines. Hence, the fuel saving potential of the SCE rests upon raising the load points and additionally saving the whole friction losses of the non-fired cylinders. A detailed full vehicle simulation determines the SCE’s fuel saving potential. All fundamental investigations concerning the whole concepts functionality are based on testing rig and simulative studies.
This paper gives a precise description of the mechanical structure of the SCU itself and its mode of operation, followed by the detailed modelling specifications of the whole SCU mechanism. The integration of the Simulink® based SCU’s simulation model into the GT-Suite® based full vehicle simulation via co-simulation is shown subsequently. The SCU’s system performance is discussed according to the results of exclusive preliminary investigations within the full vehicle environment using standardized driving cycles.
