Efficiency evaluation of gearboxes for parallel hybrid vehicles: Theory and applications

In this investigation is presented a systematic approach for the modelling and analysis of power split transmissions which include an epicyclic gear train, in various configurations, as they are used in hybrid vehicles. Emphasis is placed on the efficiency of the epicyclic gear trains and the associated power-flow in the transmission. The approach is based on the graph based representation of the kinematic chains and numerical examples are provided to further illustrate the applicability to hybrid vehicle transmissions with epicyclic gear trains and CVT elements. The graph-theory approach is shown to be a practical way to discern all possible configurations and their associated efficiencies.