Study On The Continuously Variable Transmission Tractor Productivity-Economy Comprehensive Optimal Speed Change Law

With the development of the agriculture mechanization and modernization,the requirements of market for the intelligent and high-power tractors continue to increase.The tractor which equipped the hydro-mechanical continuously variable transmission can realize continuous high efficiency power transmission and wide range step-less speed change.The research of automatic speed change law has become an important content in the development of new type of high performance hydro-mechanical continuously variable transmission tractor.The high-power wheeled tractor which equipped the hydro-mechanical continuously variable transmission as the research object,research the limitation of only variable speed tractor economic and productivity control rule to single mode control of tractor.Through analysis of the HMCVT characteristics and the tractor productivity and economy affecting factors proposes the integrated productivityeconomy optimum evaluation index of IEP,and formulated the productivity-economy optimum speed change law by analysis the influence factors of the productivity and economical efficiency of the tractor.The tractor economy related to engine fuel consumption and traction efficiency.Reducing the engine fuel consumption or increasing traction efficiency can improve tractor economy.The productivity is determined by the engine output power and HMCVT efficiency,to adjust the transmission ratio ensure that the engine output effective power can be get better productivity.So the tractor productivity-economy optimum should consider how to better integrate the engine characteristics and transmission efficiency.Considering the HMCVT efficiency and the coupling relationship with the engine,adjust the transmission ratio have a series engine speed to match at any traction and vehicle speed,so the transmission ratio need optimization calculated.Optimization results by the Matlab show that at any traction load and vehicle speed has one best transmission ratio and engine speed,the HMCVT working in the efficient location and the engine speed at fuel consumption low location when the tractor operated in the integrated productivity-economy optimum mode.The consequence also shows that the tractive performance has enhanced 8.5%,and the fuel consumption reduced 5%in the main traction work area compared with the traditional variable method.By establishing the mathematical of the tractor transmission system use the Matlab/Simulink software based on the dynamics principle to verify the productivityeconomy optimal speed change law.In order to ensure the stability of the tractor according to the target speed,the neural network PID control algorithm is used to control the tractor driving speed.The simulation experiment is carried out according to the law of productivity and economy and the law of the optimal speed change and control strategy.The neural network PID controller simulation on the tractor dynamics model and comparison with the PID control simulation.The stronger adaptive ability and robustness of the neural network PID control of tractor.The tractor realizes productivity-economy comprehensive optimum by regulating the HMCVT and the throttle,which provides the reference for developing the tractor automatic transmission.Using the d SPACE simulation platform for real-time interface of the HMCVT transmission grasps the method.The d SPACE platform provides a reliable way to study the development of the control system of the multi range hydromechanical continuously variable transmission.