Research And Design Of Universal Crawler Based On HST In Hilly Areas

Mountainous and hilly terrain accounts for more than 43% of China’s land area,but there is still a lack of suitable agricultural machinery in mountainous and hilly areas,which brings inconvenience to agricultural production and management.At present,the power machinery in mountainous and hilly areas has problems such as large turning radius and difficult turning in small blocks.This topic designs a crawler general power chassis based on Hydrostatic Transmission(HST)in mountainous and hilly areas.It adopts full hydraulic drive and can realize in-situ steering of chassis by remote control.And through supporting small agricultural machinery and tools,can realize rotary tillage,sowing,plant protection and field transportation and other functions.Firstly,this paper analyzes the development status of walking chassis in agricultural machinery at home and abroad,and determines the research content and technical route.The research work mainly includes:(1)According to the terrain characteristics of mountainous and hilly areas,determine the working principle and overall structure scheme of crawler general power chassis in mountainous and hilly areas.According to the working environment and operation requirements of the chassis,the crawler walking mechanism is selected,and the "four wheel belt" of the crawler chassis is designed.The driving power of tracked chassis was estimated by analyzing the steering performance and dynamic performance of tracked chassis,and the parking stability of tracked chassis on ramps was analyzed.(2)According to the requirements of the crawler chassis drive,complete the design of the hydraulic system principle,and then to the hydraulic system of the main hydraulic components such as hydraulic motor,hydraulic pump and hydraulic system of auxiliary components such as hydraulic oil tank,hydraulic tubing and the cooling system into the design calculation and selection,according to the request of caterpillar chassis movement control,remote control system scheme is established,It realizes the remote control of crawler chassis forward,backward,steering and field operation.The hydraulic system is modeled and simulated based on AMESim software,and the speed changes of the tracks on both sides of the chassis are analyzed under different loads.The quality attribute evaluation function of Solid Works software is used to evaluate the centroid position of the chassis,and the working characteristics of the chassis under different center of gravity offsets are studied,which verifies the feasibility of the hydraulic system.(3)Through ANSYS Workbench software,the finite element analysis of the frame of the general tracked chassis in mountain and hill was carried out,and the material attributes were added to the model and the grid was divided.Then the frame of the tracked chassis was subjected to the load under full bending condition,and the statics analysis was carried out,and the maximum stress of the frame was 91.30 mpa.The maximum deformation is0.54 mm,and the stiffness and strength of tracked chassis meet the statics design requirements.According to the simulation results,the natural frequency of the frame avoids the excitation frequency imposed by the engine on the tracked chassis frame and the vibration frequency imposed by the ground surface on the walking machinery,so the resonance can be avoided.(4)The trial-production work of the prototype was completed,and the linear walking characteristics,steering performance and field rotary tillage operation were tested by integrating the small rotary cultivator.The test results show that the speed range of chassis is 0～3.5 km/h,and the deviation degree of straight-line driving is 5.14%.The average radius of no-load unilateral braking steering on cement road is 0.961 m,and the average radius of in-situ steering is 0.096 m.Through the test,it can be seen that the track chassis can realize forward steering on one side and reverse steering on the other side,and the steering radius is small,which can realize the small radius steering on mountain and hilly land.The field experiment showed that the depth of rotary tillage was 0.083 m,the width of rotary tillage was 0.92 m,and the soil fragmentation rate was 92.5 %,which could meet the expected requirements of rotary tillage operation.