Design And Analysis Of Hydraulic Lifting System Of Combine Harvester Cutting Table

With the rapid development of large-scale and high-end agricultural equipment such as combine harvesters in China,the demand for high-performance electro-hydraulic proportional components and systems is increasing.There are few studies on electro-hydraulic basic parts supporting high-end agricultural equipment in China.Most of the domestic combine harvester header lifting control methods adopt manual operation control,and the control precision is low.The hydraulic system adopts the happy quantitative pump,which is laborious and energy-saving.In this paper,the design of the hydraulic system of the combine harvester header is studied.This research has practical application value for the development of the combine harvester.On the basis of the traditional combine harvester hydraulic multi-way valve,an electro-hydraulic proportional multi-way valve is designed and improved,and its performance has large load and subdivided displacement output characteristics.AMESim software is used to simulate and analyze the structure of differential pressure reducing valve,bidirectional balanced hydraulic lock and main valve.The whole simulation model of electro-hydraulic proportional multi-way valve is established.Maxwell software is used to design and analyze the proportional electromagnet,and the data of its horizontal force-displacement characteristics are obtained.It can be seen from the results that the effective stroke of the proportional electromagnet armature is between 2 mm and 5 mm,and the effective current portion is between 0 mA and 1200 mA.In this range,when the proportional electromagnet is working,the result is accurate and reliable.The simulation models of electro-hydraulic proportional multiplex valves and load sensitive pumps are built by AMESim software,and the simulation model of hydraulic lifting system of combine harvester is established.The horizontal force-displacement data of the obtained proportional electromagnet is input into the system simulation model as the pilot signal,and the pressure,flow rate and header motion curve of the hydraulic system are obtained.It is seen from the simulation results that the header lifting hydraulic system responds quickly and the designed electro-hydraulic proportional multi-way valve has a reasonable structure.A header lifting control method based on combination of bit wave integrated control and fuzzy PID control is proposed.Use the header position sensor and the ultrasonic sensor to jointly detect the header height.The obtained data is transmitted to the single-chip microcomputer and compared with the actual cutting height,and the fuzzy PID algorithm is used for the control processing,and the height of the header is automatically adjusted.Based on the control method,the hardware circuit design of the header hydraulic lifting control system is carried out.The electro-hydraulic proportional multi-way valve was trial-produced and tested to test the main performance of the valve.The test results show that when the input current increases from 600 mA to 1200 mA in steps,the output flow of the electro-hydraulic proportional valve increases linearly,and the proportional characteristics are obvious.The prototype electro-hydraulic proportional valve was installed.The header lifting control method combining bit wave integrated control and fuzzy PID control was introduced into the combine harvester control system,and field trials were carried out.The test results are basically consistent with the simulation results,which the high-precision control of the header lifting can be realized,and the working environment of the harvester can be adapted.