Research On Traction Performance Of Hydra-mechanical Transmission Of Loader

The loader operating conditions are complex and changes drastically.In order to enable the loader to achieve stepless adjustment during operation,the Hydra-mechanical compound transmission scheme is proposed to replace the traditional hydraulic transmission scheme.Hydra-mechanical compound transmission makes full use of the high power density characteristics of the hydraulic transmission,the stepless speed regulation characteristics,and the high efficiency of the mechanical transmission to ensure that the loader can achieve variable speed and high transmission efficiency.However the traction performance of the loader has a direct impact on its production efficiency.The study of its traction performance on the premise of Hydra-mechanical compound transmission lays a theoretical foundation for the design and improvement of the rear.This paper takes the wheel loader as the research object,which applies the Hydra-mecha--nical compound transmission to the loader transmission process and mainly studies:(1)The principle and structure of hydraulic mechanical compound drive are analyzed,and the two schemes of output shunt and input shunt are compared respectively.Compared and analyzed the variable speed characteristic,the efficiency characteristic,the hydraulic power shunt ratio characteristic,the torque characteristic,the speed performance and the steady change section condition under the two kinds of transmission modes.Finally,it is concluded that the input shunt is better than the output shunt in the loader transmission system,and the input shunt is chosen as the final transmission scheme.(2)The traction performance of construction machinery is analyzed and calculated.According to the traction balance and traction power balance equations of construction machinery,the traction dynamics model of loader is established,and the relevant performance index of loader traction characteristic is analyzed.(3)The relevant performance parameters of loader are matched and calculated.On the basis of Hydra-mechanical compound transmission,the matching conditions of loader parameters are analyzed,and the parameters of loader hydraulic and mechanical system are obtained according to the relevant constraint conditions.(4)The system is simulated and analyzed.The simulation model of Hydra-mechanical compound transmission is established in MATLAB/Simulink,and its tractive force,driving speed,output torque and so on are analyzed under the condition of load change.It is concluded that the traction characteristic of Hydra-mechanical transmission is better than that of hydraulic mechanical transmission,which lays a theoretical foundation for the further design of hydraulic mechanical stepless transmission.