Dual Mode VCS - Variable Compression System
System Integration and vehicle requirements 2019-01-0248
Future legislation scenarios as well as stringent CO2 targets, in particular under real driving conditions, will require the introduction of different powertrain technologies. Beside the increasing electrification of the powertrain, it will be essential to utilize the full potential of the internal combustion engine. There is clearly a competition of different ICE-Technologies. VCR systems are expected to be introduced to a considerable number of next generation turbocharged Spark Ignited (SI) engines in certain vehicle classes. The implementation of Miller or Atkinson cycles is an essential criterion for increased geometric CR. The DUAL MODE VCSTM enables a 2-stage variation of the connecting rod length and thus of the compression ratio. The concept allows a modular integration into existing engine families without significant modifications of the engine architecture and thus represents a cost-attractive solution.
The paper describes the integration of the VCS-system as well as the corresponding adaptation of the hydraulic control system into a 2,0L-TGDI-Engine in the vehicle boundaries of a midsize SUV.
Switching strategies, as well as the importance of short switching duration under WLTP as well as RDE requirements are discussed.
The applied fail safe operation and VCS - position control and detection will be described.
Finally the FC impact of the VCS system is discussed. For the 2,0L-TGDI engine in the actual vehicle class, dependent on the load profile and the specific power and torque a CO2 reduction between 5% and up to 9% in the WLTP is seen achievable.
Wolfgang Schoeffmann, Helfried Sorger, Siegfried Loesch, Alois Fuerhapter, Wolfgang Unzeitig, Thomas Huettner
AVL LIST GmbH, AVL Powertrain Engineering Inc