Design And Research Of Hydraulica System Of Spray Boom Of Wide Boom Sprayer

With the rapid development of modern agriculture and scale planting,wide boom sprayers are widely used in large farms at domestic and abroad because of their high operational efficiency.Due to the complexity of the farming environment and spatial and temporal variability,wide boom sprayers are susceptible to the impact of the farm ground,even if the spray boom produces a small angle of tilt will lead to large changes in the displacement of the end of the spray boom,resulting in the occurrence of scratching crops,and even the spray boom touch the ground,damage and other phenomena.To avoid this phenomenon,foreign wide boom sprayers are equipped with active balancing and ground profiling systems to improve the boom’s responsiveness to ground changes,maintain a stable height between the spray boom and the crop canopy,improve droplet deposition uniformity and reduce droplet drift during operation.In comparison to foreign countries,few domestic wide boom sprayers are equipped with active balancing and ground profiling systems.The performance of the hydraulic system,as the key actuating component of the active balancing and ground profiling system,directly determines the responsiveness and stability of the active balancing and ground profiling.The performance of the hydraulic system,as the key actuating component of the active balancing and ground profiling system,directly determines the responsiveness and stability of the active balancing and ground profiling.Due to the characteristics of wide boom sprayer with high inertia and sudden changes in load,the hydraulic system’s impact resistance,fast response and stability are demanded.Foreign hydraulic systems are costly and do not match domestic boom sprayers,making it difficult to apply them directly to domestic models.Therefore,it is important to design a spray boom hydraulic system with both active balancing and ground profiling for domestic models.The main research elements are as follows:(1)Hydraulic system design and modification.In order to solve the problems of the research group existing wide boom sprayers,which cannot act in concert with multiple cylinders,the flow rate is not adjustable,and does not have the ground profiling and active balancing function and other issues.Based on the load-sensitive principle,a load-sensitive hydraulic system with a dosing pump using the valve front compensation method is designed.Through Solid works/motion simulation,the maximum load of the hydraulic cylinder is determined and the size of the hydraulic cylinder in the retrofit is calculated according to the actual installation space.Select the hydraulic valve based on the maximum working pressure,working flow rate and minimum stable flow rate,and complete the hydraulic system modification.(2)Hydraulic system modeling and simulation.To study the response stability,speed and accuracy of the spray boom ground profiling system,a mathematical model of a proportional valve-controlled asymmetric cylinder is established.PID control is applied to optimize the system performance so that the ground profiling system can meet the system requirements in terms of response stability,speed and accuracy.(3)Modeling and simulation of dynamic pressure feedback device.To reduce the peak pressure shock in the hydraulic system during spray boom adjustment,thus attenuating the vibration during spray boom adjustment.A theoretical analysis of the pressure shock phenomenon generated during the adjustment of the ground profiling system,and design a dynamic pressure feedback device.The mechanisms of the initial filling volume,initial filling pressure and throttle valve opening diameter on the performance of dynamic pressure feedback device in absorbing pressure shocks are discussed.The simulation model in MATLAB/Simulink is developed to optimize the design of the three main parameters to design a dynamic pressure feedback device with better performance in the existing spray boom space installation position.(4)Hydraulic system performance analysis.To verify the performance of the designed hydraulic system,a simulation model of the wide boom sprayer spray boom hydraulic system is built using Amesim software.Simulation tests on the cooperative action of multiple hydraulic cylinders under different loads,different flow rates and emergency stop conditions are conducted.The results show that the designed hydraulic system has multiple hydraulic cylinders acting simultaneously without affecting each other,and has strong resistance to load change,strong resistance to flow saturation,and strong self-locking performance.(5)Test study.In order to verify the performance of the designed hydraulic system and the dynamic pressure feedback device,the tests of differential pressure at both ends of the valve port of the proportional valve,the test of simultaneous operation of multiple hydraulic cylinders,the test of absorbing pressure shock by dynamic pressure feedback device,and the test of step response are conducted respectively.The test results show that the pressure compensator and constant differential relief valve work stably during the system operation,and the compensation pressure value is 0.9MPa.The hydraulic cylinder flow error is 3.2 % under load variation.Step response test shows that the hydraulic system responds quickly,reaching the set threshold interval within 2 s.However,too small a threshold can affect system stability.Pressure shock tests show that the optimized dynamic pressure feedback device absorbs shock pressure with an insertion loss of 6.86 d B.