The Application of the Milner CVT as a Novel Power Splitting Transmission for Hybrid Vehicles

Hybrid vehicles are becoming an increasingly popular choice for both consumers and manufacturers due to their potential for superior fuel economy and low emissions compared with conventional vehicle power trains. Traditionally there have been two types of hybrid vehicle configurations; the parallel hybrid configuration takes advantage of power regeneration for short periods of zero emissions operation, whilst the series hybrid configuration acts as a continually variable transmission (CVT) so that increased engine efficiency can be obtained. The recent interest in hybrid vehicles has led to a number of non-traditional configurations, most notably the power-splitting hybrid electric vehicle, which uses an epicyclic gear as the power-splitting device, and can operate as either a series or a parallel hybrid. A further improvement to this configuration is proposed with the use of a Milner CVT (MCVT) to replace the epicyclic gear set. This offers greater simplicity, as well as the efficiency advantages of using a mechanical CVT to transmit power from either the internal combustion engine or the energy storage device (or both) to the final drive of the vehicle. The vehicle configuration is discussed in detail, including modelling of the MCVT, power flow analysis of the system, selection of the specific vehicle configuration and potential driving modes.