Gasoline Engines for Hybrid Powertrains – High Tech or Low Cost?

Authors

Dr.-Ing. J. Scharf, Dipl.-Ing. J. Ogrzewalla, Dipl.-Ing. K. Wolff, Dr.-Ing. T. Uhlmann, Dr.-Ing. M. Thewes, Dr.-Ing. A. Balazs, Dr.-Ing. P. Grzeschik, Dipl.-Ing. M. Görgen, S. Yadla MSc, FEV Europe GmbH, Aachen; Dr.-Ing. H. Baumgarten, FEV Group GmbH, Aachen; Dr.-Ing. M. Wittler, FEV Consulting GmbH, Aachen; C. Nebbia MSc, FEV Italia, S.r.l., Rivoli

Year

2017

Print Info

Fortschritt-Berichte VDI, Series 12, No 802

Summary

Based on a market study for Europe, the USA and China, this publication predicts a shift towards environmentally sustainable drive systems. The main factor for this trend is the electrification of the drive train. Although the majority of all sold vehicles in Europe (75 to 85%) will still have a combustion engine in 2030, a high proportion of these combustion engines will be operated in hybrid power trains. The results presented here illustrate the electrification of the powertrain from a gasoline engine perspective for a D-segment vehicle with a mild-hybrid drive with 48 V belt starter generator, a mild-hybrid drive with integrated 48 V starter generator, a power-split full-hybrid drive and a plug-in hybrid drive. They demonstrate that simplified naturally aspirated 4-cylinder engines as well as turbo-charged 3-cylinder engines with stronger technology are equally suited for a cost- and CO₂-optimised use in hybrid powertrains. The influence of the combustion engine on the CO₂ emissions reduction decreases with an increasing degree of electrification, and the requirement of a compact design becomes more important. Consistently low emissions and low fuel consumptions under real driving conditions speak for a deliberate reduction of the engine technology and a moderate choice of the degree of downsizing. A parametric package evaluation shows that the more compact turbo-charged 3-cylinder engines (especially in a plug-in hybrid) are very favourable. They can be transferred through fairly simply on/off technology packages from mild-hybrid powertrains to strongly electrified powertrains. In combination with uniform displacements it is possible to transfer this concept to various vehicle segments. It is recommended to avoid simplification when designing exhaust gas aftertreatment systems for combustion engines in hybrid powertrains to guarantee lowest emissions even under real driving conditions and variable user behaviour. A corresponding design guideline is presented.