Research And Design Of HMT Variable Speed System In High-speed Transplanter

The speed variator of high-speed rice transplanter has direct influence on efficiency,dynamic performance, fuel economy and portabilidy of shift control. With the use of hydraulicmechanical stepless variable speed system, the performance of high-speed rice transplantercould be improved. The speed variator combines hydraulic transmission and mechanicaltransmission by using hydraulic mechanical stepless variable speed system，which is suitable forapplying in high-speed rice transplanter. Hydraulic transmission and mechanical transmissionare connected in parallel, partial of the power is undertaken by hydraulic transmission, and theother is afforded by mechanical transmission. High efficiency is ensured by mechanicaltransmission and stepless speed regulating is ensured by hydraulic transmission. Hydraulicmechanical stepless variable speed system contains both high efficiency and stepless speedregulating. Regulating speed by hydraulic mechanical stepless variable speed system, thestructure of power transmission system is able to simplified. Drivers can regulate the speed, goforward or backward with simple operations. Taking high-speed rice transplanter as the researchobject, this paper has designed a hydro-mechanical variable transmission, which is matched withthe transplanter, and the transmission characteristics was researched. Based on the mechanicsanalysis of the gearbox, the optimized design was done. The main research work are shown asfollows:1）This paper summarized the classifications of the transmission, reviewed the researchstatus of variable speed device in high-speed rice transplanter at home and abroad, summarizedthe working principle and characteristics of variable speed device of high-speed rice transplanterabroad.2）According to the research of working principle and characteristics in speed variator ofadvanced transplanter at home and abroad, transmission scheme was determined preliminarily.The details of transmission scheme were designed later. Then the transmission system, shiftsystem, and planting distance of HMT were explained in details.3）Aimming at minimum volume of the gearbox, this paper took structural parameters andforce of gears and shafts as constraint to design planet row. Using the Sequential QuadraticProgramming (SQP method) and the tool box of MATLAB, optimized structure of planetary gear train in transplanter has been designed. Proper optimization results were obtained and the targetof light weight was obtained. The whole weight of the transmission was reduced and themanufacturing cost was lower. Through static force analysis on the designed gearbox, thefoundation of structure analysis and optimization has been laid.4）Using3D software UG NX to make the model of the transmission, through virtuallyassembly, interference detection and motion simulation, the correctness and rationality of themodel was verified. Considering the largest load as example, Importing the transmissionstructure model into ANSYS, combining with finite element theory, statical force of each shaftand gears in high-speed transplanter gearbox was analyzed. The strength and stiffness of shaft,the bending strength of root tooth and the contact strength of transmission were checked.