A design approach for multi-configuration hybrid transmission mechanisms

Several hybrid architectures have been widely used in hybrid electric vehicles. For example, power-split architecture brings seamless operation, while parallel architecture makes the internal combustion engine directly drive the wheel. To combine the advantages of various architectures, this study aims to develop a design approach to create a transmission mechanism that has multiple configurations and uses these configurations to achieve several hybrid architectures. First, this study standardized hybrid transmission mechanisms using the Function Power Graph; this powerful and intuitive tool inspired several elements and an element layout for the new mechanisms. Then, several configurations with up to five elements were enumerated and organized into the databases. Next, the mechanisms with multiple configurations and a limited number of clutching units (clutches or brakes) were evaluated, 10 of which were identified as the best group that provided five parallel configurations, two 2-motor electric vehicle configurations, and a power-split configuration. At the end of this paper, a novel hybrid transmission mechanism was developed as a demonstration. It provides higher power and torque at the output but there is no need to use the larger internal combustion engine or motor-generators. This mechanism also enables the internal combustion engine to drive in overdrive parallel architectures to avoid the loss in energy conversion when the power-split architecture is not required. As a result, after a designer specifies the desired hybrid configurations, follows the procedure, and uses the configuration databases built in this study, a novel hybrid transmission mechanism will be created.