Research On Automatic Gearbox Transmission System Of High-power Corn Harvester

Corn harvester,a high power agricultural harvesting machinery,has a complex working condition and constantly changing external loads,also the performance of engine cannot be brought into full play.So the gearbox need to change rotate speed and torque timely to adapt the complex conditions,thus ensuring the fuel economy of the corn harvester.Because of the limitation of the gears number,the gearbox of our traditional mechanical corn harvester is difficult to fit the complicated and changing work condition and then reduce the transmission performance of the machine.By reason of the low transmission efficiency of the pure hydraulic and the high cost of the hydraulic components which suit the high power condition,the fledgling hydrostatic transmission system can't be used in the gearbox of high power corn harvester.So it is significant to design a gearbox of high-power corn harvester with high efficiency and can realize continuously variable transmission within a certain range.This paper analyzes the researches at home and abroad based on the working condition and operating requirements of the gearbox of high power corn harvester,the parameters of corn harvester is determined.Based on the principle of modular design,the module decomposition of the transmission system of the corn harvester automatic gearbox is conducted.Through the design of the hydraulic transmission,the mechanical transmission and the branch and bus module transmission scheme,the whole transmission scheme of the automatic gearbox of high power corn harvester is determined and the basic parameters of hydraulic system and mechanical system of the gearbox is solved.Analytic method is used to verify the existence of circulation power load of the automatic gearbox of corn harvester and with the changes of displacement ratio,pressure and rotate speed,the characteristics of the transmission efficiency of planetary gear,the efficiency of hydraulic system and the whole transmission efficiency of the gearbox are analyzed.Based on the Amesim platform,the mathematical model of hydraulic transmission system of the gearbox,planetary gear train and ordinary gear train are established and corrected.According to the revised result,the transmission efficiency model is set up and the simulation of efficiency characteristic is conducted.Contrast the result obtained by simulation and theoretical analysis,the transmission scheme is verified to meet the design requirement.According to the relevant industry standards,the test bed of the automatic gearbox of high power corn harvester is designed and the main modules such as power unit,loading device,measurement and control system,software control system,etc are designed and the parameter are selected.Based on the test bed,the testing scheme of full load transmission efficiency is determined and the test process of the efficiency characteristic is design and specified.