Simulation Study of Advanced Variable Displacement Engine Coupled to Power-Split Hydraulic Hybrid Powertrain

The simulation-based investigation of the variable displacement engine is motivated by a desire to enable unthrottled operation at part load, and hence eliminate pumping losses. The mechanism modeled in this work is derived from a Hefley engine concept. Other salient features of the proposed engine are turbocharging and cylinder deactivation. The cylinder deactivation combined with variable displacement further expands the range of unthrottled operation, while turbocharging increases the power density of the engine and allows downsizing without the loss of performance. While the proposed variable displacement turbocharged engine (VDTCE) concept enables operations in a very wide range, running near idle is impractical. Therefore, the VDTCE is integrated with a hybrid powertrain allowing flexibility in operating the engine, elimination of idling and mitigation of possible issues with engine transients and mode transitions. The engine model is developed in AMESim using physical principles and 1-D gas dynamics. A predictive model of the power-split hydraulic hybrid driveline is created in SIMULINK, thus facilitating integration with the engine. The integrated simulation tool is utilized to address design and control issues, before determining the fuel economy potential of the powertrain comprising a VDTCE engine and a hydraulic hybrid driveline.