Design And Test Of Paddy Field Caterpillar Wheel Hydraulic Drive Chassis

Rice is one of the major grain crops in China.The planting area is widely distributed and the grain output has always occupied the top three.Plant protection is an indispensable part of rice production,with an annual loss of up to 15 million tons due to pests and diseases.For a long time,manual or motorized backpack sprayers occupies a large part in rice spraying equipment.In recent years,the demand for self-propelled paddy fields has rapidly increased.Some self-propelled sprayers begin to appear in the domestic market which are Japan's imitations or dry field application machines with paddy field wheel.However,the soil characteristics of paddy fields in China,especially the farming methods,are quite different from those in Japan.After 3 to 5 operations,such machines will have slippage and subsidence,and even severely damage the farmland.Tracked wheeled chassis have good maneuverability and strong ability to pass through soft ground.They are suitable for the wet and soft environment of paddy fields.Based on double tracked chassis technology and combined with previous research,the paper designed a four-track wheeled chassis,which can be equipped with spray equipment.However,there are few studies on its performance under paddy field conditions,especially its steering performance.Therefore,based on the analysis of steering performance of the double tracked crawler,a steady driving force model for the tracked wheeled chassis is established and a prototype test was did to prove it.The influence of the parameters of the traveling wheel on steering performance is analyzed by the model,which can provide reference for tracked wheeled chassis design in paddy fields.The specific work is as follows:(1)This paper analyzes the existing problems in the plant protection mechanism of paddy field in China,and according to the rice planting agronomic,the design requirement of crawler wheel chassis is clarified.(2)The design of the chassis frame structure,the key parameters of the crawler wheel,the 3d modeling and the virtual assembly are completed.The hydraulic drive system of the crawler wheel chassis is designed to determine the system scheme of the closed loop,the volume speed regulation and the variable pump quantitative motor,and the main hydraulic components are selected and calculated.(3)The finite element analysis software ANSYS Workbench was used to analyze the stress and strain of the frame under two typical conditions of horizontal bending and limit torsion to ensure that the frame satisfies the strength design requirements;the finite element modal analysis under prestress was used to obtain the first-four frames of the frame.The natural frequency and mode shape of the order can be avoided to generate resonance with the engine.The time domain and frequency spectrum information of the frame under the excitation of the engine can be collected by a vibration tester to verify the correctness of the modal analysis.(4)Taking into account such factors as soil parameters,track slipping,slippage and steering side lateral drag resistance,a calculation model for the steady-state steering drive force of track-wheel-type chassis was established,and the driving force of the chassis under different steering radius was predicted.The simulation results and experiments show that the driving force increases with the decrease of the turning radius.Further calculations also show that when the ratio of the length of the track width is between 0.1 and 0.5,the driving force decreases with the ratio of width to length,Taking into account the soil parameters,track slip,slippage and side-dragging resistance of the steering side,a steady-state steering drive force model of the track-wheel-type chassis was established to predict the driving force of the chassis under different steering radii,and the simulation results were obtained.Tests have shown that the driving force increases with the reduction of the turning radius.Further calculations also show that when the ratio of length to length of the shoe is between 0.1 and 0.5,the drive force decreases with the ratio of width to length.This model can provide a reference for the relevant caterpillar wheel chassis in power matching optimization and structural design of the walking device.(5)A pressure transmitter and a turbine flowmeter were installed on the sample car,and a steering power test system was set up to test the steering power at different steering radius,and compared with the steering driving force model to verify the correctness of the theoretical calculation.