Systematic Synthesis of Dedicated Hybrid Transmission

The great diversity of dedicated hybrid transmissions (DHTs) requires a method to identify solutions among all potential concepts involved in each structure. Therefore, a DHT synthesis tool is developed on the basis of general transmission synthesis. In the first synthesis step, transmission structures are generated with only conventional functions such as driving with only the internal combustion engine. Electric machines are then installed in the transmissions to achieve further hybrid functions, including boosting, eCVT and electric driving modes. The number of generated transmission concepts increases exponentially with each synthesis step. Various evaluations are carried out successively to identify the most suitable DHT concepts among the many possible solutions. The generated DHT concepts are evaluated in terms of structural feasibility, driving modes, drivability and load factors on transmission components. An example of DHT synthesis involving planetary gear sets is explained in detail. The best five DHT structures are identified out of more than 120 billion solutions.