| After years of development,the performance of domestic combine harvesters has been significantly improved,but there are still problems such as relatively low level and unreasonable design of the transmission system.In response to these problems,this research put forward an optimization scheme for the transmission system of the threshing drum,cleaning fan and chopper components of the YF8166 corn grain combine by constructing a test bench,designing a power acquisition system,and carrying out power acquisition experiments.The main content and conclusions of the thesis include the following points:（1）Taking the YF8166 corn grain combine harvester as a reference,a multi-functional grain combine harvesting test bench that can simulate the process of field operations has been constructed.It was composed of feeding assembly,bridge assembly,threshing separation system,cleaning system,chopper assembly,transmission system and control system,etc,and each main components can be driven independently.（2）A power harvesting system was designed based on the multi-functional grain combine harvesting test bench.Taking the threshing drum,sieve box,fan and shredder as objects,a power acquisition system composed of three parts:torque sensor module,data acquisition module,and data analysis module was designed,and the system was tested by the method of theoretical calculation and experiment.The effect has been verified for accuracy and stability.（3）A bench test of threshing,cleaning and choppers with a feed rate of 8/10/12kg·s-1was carried out.The test materials were corn with husks in the moisture content range of 24%～26%and 29%～31%.The test factors were drum speed,fan speed,crank speed,chopper speed and fish scale sieve opening.The test indicators were crushing rate,loss rate,impurity rate and power consumption of each component.Through the analysis of the test data,the optimal parameter combination of each component under different working conditions was obtained,and the regular pattern of the power consumption of the drum,fan,screen box and chopper with its rotation speed and the feed rate of the harvester was explored.（4）Through comparative experiments,the optimized components of the transmission system were determined,and corresponding optimization schemes were proposed.A bench comparison test was carried out with the design speed of the corn grain combine and the better speed obtained from the bench test as the test parameters.Through the analysis of the test results,it was determined that the optimized components of the transmission system were the drum,fan and chopper.For the drive system of the drum,a hydraulic system suitable for PLC-controlled stepless transmission was designed.The piston cylinder’s flow rate is28.36L·min-1,the electromagnetic proportional valve’s flow rate is 40 L·min-1,and the gear pump’s displacement is 40m L·r-1;for the drive system of the fan,the relationship between the fan speed and the displacement of the driving disc of the active variable speed wheel is studied.When the driving disc of the driving wheel axially moves 1mm,the fan speed increases or decreases by 28 r·min-1;for the drive system of the shredder,the pulleys with diameters of200mm and 212mm were designed to optimize the structure of the transmission system by replacing the pulleys. |
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