There is no doubt that the modern internal combustion engine (ICE) is approaching its theoretical limits in terms of efficiency. Owed to the fact that the conversion of fuel-bound chemical energy into effectively usable power by combustion is largely defined by the fuel properties, the combustion process and the implicit phenomenon of abnormal combustion is a governing factor that limits further efficiency increases.
However, the use of a knock-resistant fuel such as methane is leading to a significant raise in the average combustion pressure and total engine efficiency. In turn this requires a base engine architecture that is specially designed to cater the increased thermal and mechanical requirements so that the positive fuel properties can be fully exploited.
Furthermore, an improvement of the energy balance is achieved by utilizing the kinetic energy stored in the vehicle by means of electrical recovery. In consequence, a positive synergy can be observed when mating this type of internal combustion engine to a hybrid powertrain. This hybrid powertrain consists of a P2 hybrid module containing an offset 48V electrical machine and a disconnecting clutch which permits the vehicle to be driven purely electrical, embedded in a board-net comprising an integrated 12V/48V battery solution to address package and complexity reduction requirements. In the light of fuel economy and cost efficiency, the 48V mHEV approach reveals as the most appropriate approach.
Following this approach, the study presented in this paper reveals that a CO2 improvement of approximately 35% percent (WLTP) can be achieved while in parallel driveability and user experience can be maintained or even be elevated.