| Potatoes are high in dietary fiber and low in fat,and can adapt to a variety of geographical conditions.In hilly areas,potato planting is mainly artificial and semi-mechanical due to the problems of small plot,scattered planting,narrow road surface and large slope.Therefore,it is urgent to solve the problem of potato mechanization in hilly areas.In this paper,according to the ground conditions and planting agronomic requirements in hilly areas,and combined with the potato and soil separation device developed in the early stage,the optimized design of a crawler self-walking potato harvester chassis suitable for hilly areas,small space steering,climbing ability,good stability.The main research contents of this topic are as follows:(1)Combined with the existing problems of potato harvester in the research group,the chassis optimization design scheme of crawler self-walking potato harvester was determined.The optimization design of chassis frame,mechanical-hydraulic transmission system and the spatial layout of parts is completed.The mechanical-hydraulic transmission system is divided into mechanical transmission system of engine-hydraulic pump and hydraulic transmission system of hydraulic pump-hydraulic actuator.The optimized mechanical transmission system has the advantages of simple transmission structure,safety and reliability,and small space for parts,which reduces the transverse size of crawler potato harvester chassis and improves the passability of crawler chassis on narrow roads.Hydraulic transmission system adopts open hydraulic circulation oil circuit,the design uses gear hydraulic triple pump to provide hydraulic oil to the implementation of the branch hydraulic components,the transmission system has the advantages of a pump multi-purpose,hydraulic oil circuit simple,low cost.The high speed hydraulic motor and reduction box are used in the chassis,which improves the effective utilization rate of the hydraulic motor and increases the walking torque.(2)Statics analysis of crawler harvester chassis frame was carried out based on ANSYS Workbench software.According to the real situation,the load of each stress point of chassis frame and the loading constraints were analyzed,and the chassis frame structure was optimized by combining the simulation data.The optimized chassis has no obvious deformation,and the equivalent stress is far less than the yield strength of the material,which meets the application requirements.(3)The centroid analysis and static slope stability theory analysis of crawler harvester chassis are carried out.The 3d model of the crawler harvester chassis was established by using Creo drawing software,and the centroid position was obtained after material definition of each component in Creo software.The center of mass of track harvester chassis loaded with the weight of potato and soil separation device is 18.07 mm,709.53 mm,and 544.01 mm in vertical direction;Compared with the original harvester,the position of centroid moved forward and the height of centroid decreased obviously,the main weight was concentrated in the middle position,and the stability of chassis was greatly improved.According to the data of centroid position,the static stability of crawler harvester chassis in longitudinal and transverse ramps was analyzed.Without considering the adhesion coefficient of crawler and ground,the maximum inclination Angle of longitudinal climbing was 52.5°,and the maximum inclination Angle of longitudinal descending was 54°;When the control platform is above the ramp,the maximum lateral inclination is 46.2°;When the control table is below the ramp,the maximum lateral inclination is 31.3°.(4)The Recur Dyn multibody dynamics simulation software was used to establish the virtual prototype of track harvester chassis,and the simulation tests of 100 meter running deviation and dynamic stability of ramp were simulated.In the simulation test of deviation of 100-meter running,the tensioning spring was set to be equivalent to the tensioning bolt of the prototype.When the right tensioning bolt maintained a normal elongation of 25 mm and the left tensioning bolt maintained a normal elongation of 31 mm,the deviation of 100-meter running was the minimum,and the minimum value was 0.9m.In the dynamic stability simulation test of the ramp,the maximum inclination Angle of the virtual prototype is 45° in longitudinal climbing and 50° in longitudinal downhill driving without considering the adhesion coefficient of ground and track;When the control platform is above the ramp,the maximum lateral driving inclination is 35 °;When the control table is under the ramp,the maximum roll Angle of lateral driving is31°.(5)The trial-manufacture and performance parameter test of crawler self-propelled potato harvester chassis were completed.The total weight of crawler harvester chassis was 1000kg;The measured track grounding length is 1250 mm,track chassis gauge is900 mm.In the in-situ turning radius measurement test,the turning radius of bilateral reverse differential is 0.74 m,and the turning radius of unilateral motor is 1.2m;Low gear driving speed is 3.5km/h,high gear speed is 5.3km/h;Test the temperature of hydraulic oil tank,hydraulic oil cooler,gear hydraulic pump,hydraulic motor and engine after different working hours of the trial-produced prototype;When the engine is idle,the speed of the gear pump is 936r/min,and when the engine is at its maximum speed,the speed of the gear pump is 2605r/min.Through the test of basic performance,the mechanical and hydraulic transmission system can meet the expected design requirements;The driving speed,weight,gauge and grounding length are consistent with the technical indicators;Hydraulic tubing without oil leakage,chassis frame without deformation.To sum up,the chassis design of crawler potato harvester is reasonable,and the trial-produced prototype meets the design requirements. |
