TwinRex – The TwinConcept for a Serial-Parallel Hybrid System With an Excellent Cost-Value Index

The TwinRex concept was developed as a dedicated hybrid system capable of meeting upcoming CO₂ regulation. The simplified transmission consists of a two gear-transmission, with a reduced number of parts, in order to achieve a good compromise between performance, weight and cost. Two Motor-Generators (MGs) are integrated into the transmission, enabling hybrid functionality with three different driving modes (EV-Mode, Series-Mode and Parallel-Mode). Depending on the sizing of the MGs different degrees of hybridization can be achieved. We conducted a design study considering a set of standard use-cases to determine the CO₂ reduction potential for the system, which is up to 19%. Simulation results show that WLTC can be handled even in layouts with low-power ICE and MGs. Moreover a right-sizing of the MGs is discussed under consideration of the possible applications of the transmission system. We show that this new concept provides a good cost-value index, helping to fulfil future CO₂ emission legislation and achieve maximum end-user satisfaction. Additionally an improvement in acceleration and drivability was shown due to a predictive engine start and gear shift strategy.