| Hydro-mechanical continuously variable transmission is a new type of transmission,which divides the input power of the engine through the hydraulic circuit and the mechanical circuit.It is mainly used in engineering vehicles and special vehicles,combining the characteristics of the high efficiency of mechanical transmission and the characteristics of continuously speed regulation of hydraulic transmission,and can keep the engine working in a highly efficient area all the time.Therefore,the study of the hydro-mechanical continuously transmission system is of great significance.The form of hydro-mechanical continuously variable transmission system structure is numerous,choosing the ideal structure is the key of the design.The characteristic of all kinds of the structure of the system is analysed based on the theoretical calculation of the transmission ratio,torque characteristics,power split characteristics and power cycle characteristics in this paper.According to the models of the appliable forklift,complete HMCVT transmission system was designed.Working principle of the system was analyzed combined with the parameters and engine steady speed control model of the forklift.And the hydraulic control system of displacement ratio control equation was provided.modeling and simulation of the vehicle was established by using the AMESim software.Accuracy of the HMCVT system was verified through the simulation of typical operating conditions analysis.Design of components of hydraulic speed control system was Completed.the power control valve for flow field was analyzed by using Fluent software.The flow and pressure with the change of valve opening curve was achieved and the system efficiency has been calculated.On the basis of theoretical analysis,hydro-mechanical transmission system experiment platform was built.Based on the experimental methods,the efficiency curve of the system was achieved,and the feasibility of hydraulic mechanical transmission system was verified. |
