Research On Automated Transmission Control System Of Hydromechanical Continuously Variable Transmission

There are increasingly high requirements in the power performance, fuel economy and comfort for the tractor, as well as the wheeled tractor with the high performance and the high power. High efficiency and high power transmission can be achieved by the hydro-mechanical continuously variable transmission. As the core parts of the tractor, the performance of the engine and the HMCVT directly affects the tractor, and so does the matching between the engine and the transmission. Therefore, there is an important significance in the research for the vehicle performance.This paper establishes the mathematical model of the engine firstly, which describes clearly the characteristics of the engine. By analyzing the characteristics curve of the engine, it can be obtained the change trend of the dynamic and economy performance of the engine with the change of the rotate speed, as well as the optimal economic and power performance curve. Taking the HMVT of the 400 horsepower wheeled tractor as the research object, the characteristic of the transmission ratio, torque, power dividing and efficiency is analyzed, as well as the calculation principle and the expression method of the traction characteristic of the tractor with the HMCVT drive. According to the characteristics of HMCVT ratio change, matching the engine and the transmission, it can be obtained the target speed ratio corresponding the target zone of the HMCVT economy and power performance under the condition of the best economy and power performance. The control principle of the automatic transmission control system and the function of the hydraulic control unit is analyzed and the component of the electronic control system is determined. For the control system, it can be designed the hardware circuit of the TMS320F2812, including the minimum system, signal input/output module and communication module. The control algorithm of the software is determined and the matlab software is used to establish the control model of pump-motor. It is proved that the superiority of the fuzzy PID is better than the ordinary PID control. The program of the control functions is designed aimed at the automatic transmission control. Finally the control system is verified to be feasible.