Dual Stage Input Coupled Split Power Transmission Efficiency Optimization

Split power continuously variable transmissions can offer clutchless transitions from reverse through park and into the forward driving mode. The advantages of these transmissions can include elimination of a launch device while maintaining the continuous variability and fuel economy benefits of conventional CVTs. This paper offers further improvements to the transmission by providing an efficiency optimization methodology. Models for the transmission are constructed. A genetic algorithm is developed for the optimization routine. The effects of the gear material strength, gear module, gear tooth width, and shaft offset on the efficiency are determined. The bearing diameters and gear parameters are calculated and reviewed. Power loss contributions are presented in conjunction with their effect on the overall transmission efficiency. Recommendation for further improvements to the methodology is made.