Configuration of the Power Reflux Hydro-Mechanical Transmission System

Abstract

The hydro-mechanical transmission system (HMTS) operates either in power split transmission mode (PSTM) or power reflux transmission mode (PRTM). Although PRTM is often ignored as a transition mode, this study reveals that the HMTS operating in the PRTM can accumulate the power input from the power source in the form of reflux power (in some references, scholars also refer to the reflux power as circulating power), thereby enabling the HMTS to exhibit a similar transmission performance as hydrodynamic transmission systems. Accordingly, this study applies the PRTM to the starting of construction vehicles and refers to the HMTS operating only in the PRTM as the power reflux hydro-mechanical transmission system (PHTS). By analyzing the internal relationship between the configuration and the power flow, transmission characteristics, energy storage mechanism, and energy loss mechanism of the PHTS, the optimal PHTS configuration suitable for construction vehicles was explored. The results indicate that reasonable configurations can enable the PHTS to significantly improve the efficiency of the construction vehicle transmission system, reducing energy consumption while ensuring power performance. Expanding the displacement ratio control range of the hydraulic speed regulation mechanism and combining the PRTM with the PSTM in an orderly manner can widen the high-efficiency range of the vehicle transmission system without increasing the number of vehicle gears.