Extreme downsizing for gasoline engines – fun to drive with extremely low emissions

This paper elaborates different boosting systems for extreme downsizing levels considering the target of optimal transient performance:• Turbocharger for 90 kW/l and 140 kW/l layout• Turbocharger (TC) and electric turbocompressor in three different layouts• Turbocharger supported by electric motor-generator unit (eTC) with and without FEV Dual Fresh Air Bypass (FEV Dual FAB)The performance benefits of the combination (TC+eC) are confirmed by FEV’s new high performance demonstrator vehicle and underline the fun-to-drive of such a concept.The addition of a 48 V eC enables improvement in time to torque between 23 % and 77 % depending on the investigated engine speed. Low-end-torque-speed can be (temporarily) shifted from engine speed of 2500 1/min to 2000 1/min. These outstanding results are based on an optimized matching of the TC and the eC, the performance of the eC unit itself and the model based ECU control. It could also be demonstrated that the favourable dimensions of the eC lead to an optimum package situation resulting in low pressure losses and therefore an optimized airpath concept.The introduction of an eTC yields great transient performance benefit especially at high engines speeds. Transient performance at low engine speeds as well as well lowend-torque is limited due to compressor surge. The addition of FEV’s Dual Fresh Air Bypass solves this drawback of the eTC in these operating conditions.