Upcoming, increasingly stringent greenhouse gas (GHG) as well as emission limits demand for powertrain electrification throughout all vehicle applications. Increasing complexity of electrified powertrain architectures require an overall system approach combining component technology with integration and industrialization requirements when heading for further significant efficiency optimization of the subsystem internal combustion engine.
The requirements on the combustion engine in hybrid powertrains are quite different to those in a conventional powertrain solution. Next-generation hybrid engines, with brake thermal efficiency (BTE) targets starting from 42-43% and aiming for 45% and above within the product lifecycle, require a re-thinking of the base engine architecture of current modular engine platforms.
At the same time focus on the product cost and minimized additional investment demand reuse of current production, machining and assembly facilities as far as possible.
A modular powertrain technology platform, including different combinations of engine power ratings, e-drive, battery, transmission and hybrid variants, with the ability to integrate different technology packages, is a proven solution. The electrification variants, from mild hybrids up to serial hybrids, allow gradually increasing adaption of the ICE towards a tailored dedicated hybrid engine.
The increasingly requested compatibility for future sustainable fuels and E-fuels, in particular Ethanol, Methanol and especially Hydrogen is an additional dimension of modularity in the engine platforms. Different fuel injection and combustion concepts, thermal and chemical impact, the demand for nearly oil-free combustion with impact on piston-Bore interface and engine ventilation, aftertreatment requirements as well as safety requirements are topics to be considered.
Focus of the paper is on the approach to balance overall complexity of the powertrain and the combustion engine, while simultaneously minimizing the trade-offs between technology and investment cost impact and efficiency and emission optimization.