Study On The Internal-Stage Control Strategy Of Hydro-Mechanical Continuously Variable Transmission

There are a series of problems exist in the engineering vehicles. First, the engineering vehicles with complex working conditions and variable job object often work under changing load conditions. This requires not only vehicles with high reliability and adaptability, but also greatly increased the difficulty of the operation. Second, with the energy crisis and the growing problem of environmental pollution, construction machinery industry is also faced with severe energy-saving emission reduction obligations and responsibilities. Therefore, it is necessary to use continuously variable transmission technology to improve the quality of construction vehicles.Hydro-Mechanical Continuously Variable Transmission which is referred to as HMCVT, is one of the continuously variable transmission. It is composed by the hydraulic governor institutions, mechanical speed change mechanism, power split and confluence device.HMCVT combines the advantages of hydraulic step less and flexible features and mechanical characteristics of high transmission efficiency. It has extensive application prospects in many field such as high-power tractors, construction vehicles, tanks and many other areas. The development of rational control strategies for the performance of HMCVT plays an important part.The principle of HMCVT was analyzed, and the characteristics of HMCVT such as speed, torque, efficiency, features and power cycling phenomenon was studied. According to the characteristics of HMCVT ratio adjustment, the match between HMCVT and tractor was carried out. A mathematical model of the engine is set up. According to the above analysis, an intelligent control strategy was proposed, whose aim is to achieve the maximum power output of engine and high efficiency of the HMCVT. A model of loaders was established based on the bond graph theory, A simulation model was built up on the Platforms of Matlab/M-File, Matlab/Simulink and Matlab/Stateflow. Simulation study verifies the above outcomes. It is useful to improve power and economic capabilities of vehicles.