Basic Performance Studies On A Power-cycling Hydro-mechanical Transmission

This paper mainly introduces a new type of power-cycling hydro-mechanical variable transmission system?PCHMCVT?consisting of hydraulic pump-motor and planetary row.This structure has the properties of improving transmission efficiency and increasing transmission speed and torque.After expounding the working principle of the power-cycling hydro-mechanical transmission structure,the formulas of basic characteristics such as speed ratio,efficiency and torque ratio are derived.,and then the structural parameters are optimized.And analyzing the influence of the gear shifting on the new power-cycling structure on the different place.The transmission characteristics of the power-cycling hydro-mechanical transmission structure are compared with the transmission characteristics of the split hydraulic mechanical transmission structure and the pure hydraulic structure commonly used in engineering vehicles.At last,I built the dynamic model of PCHMCVT system and analyzed its dynamic characteristics.And we can get the conclusion from whole analysis.This paper granted No.51875055 is part study content of the National Natural Science Foundation in China project—Design Theory and Control Method for a new PCHMCVT system.The research content is as follows:?1?A new type transmission structure of PCHMCVT system put forward.And working principle of this structure is studied.The mathematical expressions of the basic characteristics such as speed ratio,efficiency and torque ratio of the system are derived,which are provided a theoretical reference for the following parameters optimize and design of the power-cycling transmission system.?2?The basic parameters of the hydraulic pump-motor and its efficiency characteristic curve are obtained through calculation and analysis.Then,the influence of planetary gear structure parameter,hydraulic pump displacement ratio and hydraulic pump-motor efficiency of the PCHMCVT system on the transmission performance of the system is analyzed,and the regular pattern are obtained and the multi-objective genetic algorithm is used to optimize and design the system.Under the premise of ensuring the system's speed regulation performance,economic performance and torque performance,the Pareto solution set of the planetary gear structure parameters is obtained by establishing the multi-objective optimization mathematical model of the system and the NAGA-II multi-objective genetic algorithm.When??29?0,the planetary gear structure parameter is ₁k?28?2.361,and when??27?0 the planetary gear structure parameter is ₂k?28?3.122.?3?Three kinds of structures of the power-cycling hydro-mechanical transmission system gear shifting in different positions are introduced,and the basic characteristics are compared and analyzed to obtain suitable working conditions for different structures.Then compare and analyze the basic characteristics of the power-cycling hydro-mechanical transmission and the split hydro-mechanical transmission,and obtain the advantages of low-speed and torque-increasing of the power-cycling transmission structure.Finally,the efficiency characteristics of the power-cycling and pure hydraulic transmissions are compared and analyzed,and the transmission characteristics of the power-cycling structure are excellent.?4?The dynamic model of the hydraulic pump-motor system and the planetary gear are built respectively.Based on those models,the dynamic model of the power-cycling hydro-mechanical transmission is established.Then based on the model of the power-cycling hydro-mechanical transmission,the output torque of the power-cycling hydro-mechanical transmission is analyzed in depth when the system inputs the fluctuating torque.It is verified that the power-cycling hydro-mechanical transmission has good shock absorption performance and low speed and increased-torque effect.