| Transmission is an important part which is to improve the tractor of the control performance, and its development of transmission technology is an important field of the development of tractor technology. Hydro-mechanical continuously variable transmission referred HMCVT can significantly improve the vehicle power performance, fuel economy and the operating comport, this device has been widely used in developed countries tractors. With the strong pull of national subsidies of agricultural machinery and intensification of farm machinery, it’s more and more increasing that the high power and the high performance of wheeled tractor need to the demand, and the research of HMCVT of high power has an important significance.This paper expounds the transmission principle of HMCVT, and researches the high-power wheeled tractors and multi-range HMCVT from the multi-range HMCVT of drive principle to transmission system and control system of mathematical modeling and to the control simulation. To more than400horsepower wheeled tractor period of HMCVT for the study, analyze the transmission principle, and research the transmission characteristics of HMCVT from four aspects such as the transmission ratio and synchronous change period and torque characteristic and power diversion characteristic. According to the composition of the transmission system of HMCVT, having established the model of transmission system dynamics of periods of HMCVT, the model of variable pump and quantitative motor, the model of dual planetary line and the dynamic model of the tractor, as adopting the modular method. In order to reduce the tractor of shifting impact and improve the transmission performance, study the characteristics of clutch switching state when the tractor of HMCVT is in this shift; make use of the quadratic optimal control method, clutch hydraulic control model is established; analysis of the period of logic control condition, make use of the finite state machine theory to determine the exchange segment control strategy; establish the simulation model of periods of HMCVT which achieves the continuously variable transmission and paragraph control. Combine the double planetary line agency through model analysis in the working environment of Adams with the modules of Simulink tool, create a clutch switching characteristics of the model. Together transmission system with control system which having established the HMCVT through Matlab/Simulink tools, and simulate analysis of dynamic characteristics in the process of the clutch switching, it’s showed that design scheme about HMCVT is reasonable, and it’s also verified that the control strategy is feasible. |
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