Research On Character And Simulation Of Hydraulic Mechanical Continuously Variable Transmission

Transmission is one of the important components of the forklift power transmission system,the conventional transmission employ the step-variable transmission,but that transmission’s ratio can’t realize is fixed,so it can’t ensure the engine always operates at its optimum working area.Hydro-mechanical Continuously Variable Transmission(HMCVT) is a new type transmission device,that’s transmission consists of a mechanical transmission combined in parallel with a hydraulic transmission.,which make full use of high efficiency of the machinery and hydraulic characteristics of adjustable speed.HMCVT variable transmission can both achieve infinitely variable transmission ratio and ensure the engine works in the best position. So this paper studies the HMCVT.The main contents of this research are introduced as follows:(1)By reading a lot of literature, briefly introduced the history of the development of transmission, described the current situation and application prospect of HMCVT, analyzed the theory of HMCVT transmission system,studied and discussed each of the two forms of transmission:the structure and properties of input coupled hydro-mechanical transmission and output coupled hydro-mechanical transmission.Through comparative analysis, pointed out that input coupled hydro-mechanical transmission is better to apply to vehicle transmission.(2)According to the requirements of actual working condition of forklift,matching the power system for the given target vehicle,after selecting the engine,combined with the analysis of the characteristics of HMCVT,selected the reasonable hydraulic transmission,designed the suitable mechanical transmission parameters and a complete set of HMCVT transmission scheme.(3)In the simulation software Matlab/Simulink,models of all parts of the transmission system were created including the engine model% HMCVT model、 efficiency model.Respectively to engine speed along the best efficiency and best performance curve acceleration process simulation. The simulation results accord with the design requirements.(4)Based on the HMCVT test bench,completed tow kinds of no-load and loading experiment,verified the feasibility and efficiency of HMCVT theory feature.