A Numerical Modeling Study of a New Type of Hydraulic Mechanical Continuously Variable Transmission (HMCVT) with Optimized Transmission Efficiency

Hydraulic mechanical continuously variable transmission (HMCVT) is widely used in powerful tractors due to its excellent performance. This paper aims to find universal methods for analyzing and optimizing the transmission efficiency of HMCVT. The energy efficiency improvement of HMCVT is important for the economy of powerful tractors. Firstly, by correctly analyzing the transmission efficiency of HMCVT, the transmission efficiency during the operation of HMCVT can be accurately calculated. Secondly, an improved NSGA-II genetic algorithm was adopted to achieve dynamic optimization of shifting points through transmission parameter combination optimization, ensuring smooth shifting while improving overall transmission efficiency. According to the transmission efficiency simulation platform, the accuracy of the transmission efficiency calculation was verified. Adopting an improved NSGA-II genetic algorithm to continuously optimize the design of HMCVT configurations achieves dynamic optimization of HMCVT parameters without being limited by shifting speed. The specific HMCVT structure proposed in this study can meet the requirements of a three-speed continuously variable transmission at speeds of 0–50 km/h. Meanwhile, the improved NSGA-II genetic algorithm can effectively provide support for the design of various HMCVT powertrain systems.