Rapid Physics-Based Synthesis of Diesel Engine Models for Hybrid Powertrain Optimization

Concept-phase planning of diesel-engined hybrid vehicles requires rapid engine synthesis, including brake specific fuel consumption (BSFC) estimation, with minimal input data. Fuel savings from hybridization arise partly through engine downsizing and engine-off operation, so trade studies depend on knowing the dependence of BSFC on engine sizing and speed and load conditions. This paper presents a method for synthesizing hypothetical modern diesel engines of any given size for the purpose of trade studies, while matching the performance and efficiency capabilities of commercially available units. Relationships are developed between rated power, rated speed, peak torque, displacement and cylinder count for four vehicle application classes. Together with a BSFC estimation method, these relationships form a complete engine synthesis chain from rated power to a full torque curve and BSFC map, with provision for substituting known data, including minimum BSFC, where available. The method supports continuous scaling.