Design And Simulation Optimization Of Hydraulic System Of Grain Combine Harvester

The hydraulic system of the grain combine harvester is an important power transmission system in the harvester,and its performance determines the reliability and energy saving of the harvester.According to the operation function and performance requirements of the harvester,This paper uses theoretical analysis,simulation optimization and experimental research methods to carry out the dynamic characteristics of the hydraulic system of the harvester,which is of great significance for improving the reliability of the hydraulic system of agricultural machinery and improving the energy utilization rate.The thesis takes 4LZ-8.0 grain combine harvester as the research object,and analyzes its function and structure.The thesis completes the transformation design of the grain combine harvester,the determination of the walking parameters and the technical parameters of each harvesting component.Aiming at the phenomenon that the harvester changes its mass and centroid during the leveling process,the paper introduces the coupling relationship of leveling dynamic load,and uses the motion decoupling operation to establish the car body dynamics modeling.Through the model analysis of the 1/4 car body leveling system,three spring-damping-mass elements are established.A quarter-degree-of-freedom harvester leveling dynamics system model,and finally a vehicle leveling dynamics system model is established.This paper uses ANSYS simulation software to analyze the reliability of the main structure under the extreme load,and it is concluded that the designed frame meets the strengthrequirementsoftheharvesterwhenimplementinglevelinghydrauliccontrol.The paper starts with the composition structure and working principle of the grain combine harvester,and determines that the hydraulic system of the harvester is generally composed of a walking system,a leveling system and a harvesting system.According to the speed and power of the harvester components,the paper draws on the main parameter determination expressions in the hydraulic system and related hydraulic theory to develop the harvester hydraulic system design.The thesis designs a hydraulic system that satisfies the work of the grain combine harvester.The thesis starts with the mathematical model of the hydraulic system components built by the main hydraulic components,and delves into the factors that affect the performance ofthe main components of the hydraulic system.The paper uses AMESim simulation software to analyze the dynamic characteristics of the main hydraulic components of the harvester hydraulic system.The text results show that the displacement of the variable pump will not change with the change of the load;The expansion and contraction time of the hydraulic cylinder increases with the increase of the leakage coefficient.The start-up time of the hydraulic cylinder is related to the load.The larger the load,the longer the start-up time.The time it takes for the hydraulic cylinder to extend to the set position increases as the load increases.The leakage coefficient of the torque value of the hydraulic motor cylinder increases and decreases,and the oil leakage coefficient has a great influence on the torque;it provides a theoretical basis for subsequent hydraulic system design and simulation modeling.The thesis uses AMESim simulation software to model and simulate the designed harvester walking,leveling and header hydraulic system.By analyzing the influence of its dynamic characteristics on the stability of the harvester,the thesis proposes an optimized plan for the hydraulic system,which is verified by simulation software.The results show that the variable motor is used in the walking hydraulic system of the harvester.The motor speed fluctuation trend is relatively smooth,which can produce a large speed value.It has a large speed range,can produce a large torque output range,and can improve energy use rate.The relief throttle valve is used in the header hydraulic system.When the load of the system changes,the hydraulic system keeps the system flow and speed constant under the action of the overflow throttle valve speed regulation,the control element moves smoothly and reliability.In the leveling process,by adding a pressure compensator,the stability of the cylinder movement is effectively improved,the stability of the car body leveling work is improved,and the installation of the accumulator device improves the energy-saving effect of the hydraulic system.The thesis completed the prototype construction,and carried out the experimental research on the hydraulic system of the harvester walking,car body leveling and simulated harvesting respectively.The prototype uses PLC as the system control center,and completes dynamic data collection of various hydraulic components through various sensors and other detection components.The results show that the test results of walking,leveling andharvesting functions of the harvester are in good agreement with the simulation results.The test results are in accordance with the hydraulic system design values,verifying the feasibility and correctness of the hydraulic system design.