| Rapeseed is an important source for the production of vegetable oil while the middle and lower regions of the Yangtze River is one of the main rapeseed production areas in China.The development of rapeseed combine harvester plays a core role in improving harvest efficiency and reducing labor intensity.However,the adaptability of the rapeseed combine harvester remains to be improved.As a solution of the problems like huge structure,long route of materials motion that existed in the conventional combine harvester,a 4LYZ-2.0 type rapeseed combine harvester driven by the hydraulic system was designed based on the special biological characteristics of rape plant.The main structure and working process were determined.As one of the key components of the harvester,the cleaning system directly affected the harvesting performance.The fan and vibrating screen were generally utilized as the cleaning device in the conventional combine harvesters,leading to some issues like complex structure and larger vibration.To provide a solution,a cyclone separation cleaning system was designed.Furthermore,an alternative process route,which combined the rotary sieve and cyclone separation,was put forward.The test-bed and field experiments were carried out to find out the better process route,form of feeding device and rotary sieve.The research could provide a reference for the structural improvement and optimization of cleaning device for rapeseed combine harvester.The research in more detail including:(1)The process route and basic parameters of 4LYZ-2.0 type rapeseed combine harvester were analyzed.The key components of the harvester included the header,shredding and throwing device,longitudinal flow threshing and separating device,cyclone separation cleaning system,etc.The power of the working components was provided by the hydraulic system.The shredding and throwing device was used to achieve the preliminary cutting of the stalks,stabilize the load of threshing and separating process,and achieve the short route migration of the materials.The operating parameters of the harvester were analyzed and determined.Meanwhile,the rationality of the structure layout was verified.The width of the header was determined to be 2000 mm,the feeding rate was 1.5 kg/s-3 kg/s,and the engine power was 72 k W.(2)The basic structure of the cyclone separation cleaning system was designed.The key components included the feeding device,cyclone separator with double cones,pipe,centrifugal fan,etc.Two process routes,one used the cyclone separation cleaning system and the other one added the rotary sieve,were put forward based on the input and output feeding rate of the 4LYZ-2.0 type combine harvester.The forced feeding belt and the blower were determined to be the feeding devices to reduce the damage of the seeds.The conical sieve and cylinder sieve were designed as the rotary sieves to achieve the quick motion of materials inside the sieves.(3)The parameters analysis of the key components was carried out.The parameters of forced feeding belt and the blower were analyzed.The relationship between the belt velocity and the materials initial velocity when entered the cyclone separator was found out based on dynamics analysis.The rotational speed of the blower was not less than 569.6 r/min.The impeller diameter was 300 mm.The lifting height was 0.6 m.The angle of the throwing pipe was 70°.According to the difference between the suspension velocity of different components in the threshing outputs,the value of the diameter of the MOG outlet was calculated as 150 mm.The diameter of the cylinder part of the cyclone separator was 340 mm.The critical rotational speed of the conical sieve and cylinder sieve were 40 r/min-70 r/min and 30 r/min-60 r/min,respectively.(4)The comparison of the two process routes was carried out in the test-bed experiments.The effects of forced feeding belt and blower were compared in the process route that only used the cyclone separation cleaning system.a)The results of the single-factor experiments of the forced feeding belt showed that the cleaning performance was better when the rotational speed of the belt was 500 r/min to 600 r/min.The results of quadratic orthogonal rotating combination experiments showed that the best operation parameters combination of cyclone separation cleaning system was the MOG outlet velocity 15.3 m/s and forced feeding belt velocity 1.57 m/s.The cleaning ratio could reach 96.77% in theory.b)The results of the single-factor experiments of the blower showed that the better velocity and speed ranges of the MOG outlet and the blower were 18 m/s-22 m/s and 500 r/min-700 r/min,respectively.The results of the orthogonal experiment showed that the optimal parameter combination of MOG outlet velocity,blower speed,the upper cone angle,rapeseeds outlet diameter was 22 m/s,600 r/min,30° and 200 mm,respectively.The cleaning ratio and loss ratio were 91.50% and 6.02%,respectively.The influence of conical sieve and cylinder sieve were compared in the process route that combined cyclone separation cleaning system and rotary sieves.c)The results of single-factor experiments of the conical sieve showed that the optimal rotational speed range of conical sieve was 40 r/min-60 r/min,and the appropriate velocity ranges of inlet and MOG outlet were 3 m/s-5 m/s and 24 m/s-28 m/s,respectively.The orthogonal experiments showed that the optimal combination of parameters was the rotational speed of conical sieve 40 r/min,inlet velocity 3m/s and MOG outlet velocity 24m/s.Under the optimal combination of parameters,the cleaning ratio and loss ratio were 88.99% and 4.86%,respectively.d)The orthogonal experiments of cylinder sieve were carried out based on EDEM.The optimal combination of parameters was the rotational speed of promotion device 80 r/min,cylinder sieve rotational speed 35 r/min and the number of sawtooth on promotion device 6.Under the optimal combination of parameters,the total loss ratio and cleaning ratio were 4.83% and 85.7% respectively.(5)The influence of the structure and working parameters of the cyclone separator with double cones on the airflow field was analyzed based on CFD.a)The effects of inlet velocity and MOG outlet velocity on the airflow field were explored.The velocity and pressure of horizontal planes and center axial were defined as the indexes.The mathematical models between the factors and indexes were built.The constraint condition was built based on the different suspension velocity and the optimization objective function was established.The optimization results showed that the optimal combination of inlet and MOG outlet velocities were 4.25 m/s and 29.87 m/s,respectively.b)The single-factor experiments to explore the influence of the upper cone angle,the diameter of the cylinder part,the height of the cylinder part,the lower cone angle,rapeseed outlet diameter on the airflow field was carried out.The symmetry and continuity of the airflow field status inside the cyclone separator were considered to be the indexes.The results showed that the better combination of structure parameters was the upper cone angle 30 °,the diameter of the cylinder part 350 mm,the height of the cylinder part 240 mm,the lower cone angle 75 °,rapeseed outlet diameter 200 mm.(6)The field experiments of two process route were carried out.The cleaning ratio and loss ratio were considered to be the indexes.The results of the field experiment showed that the cleaning ratio of the cyclone separation cleaning system using the forced conveyor belt and blower was 94.45% and 90.21%,respectively.The loss ratio was 7.73% and 6.54%,respectively.On the other hand,the cleaning ratio of the cleaning system with conical sieve and cylinder sieve was 86.8% and 84.4%,respectively.The loss ratio was 6.7% and 5.9%,respectively.The comparison of the two routes showed that the cleaning ratio of the process route using the cyclone separation cleaning system was higher.The loss ratio of the process route combined with the rotary sieves was lower.The difference between the cleaning ratio and loss ratio under different routes were not obvious.The structure of the process route using the cyclone separation cleaning system was more simplified.The research provided a reference for the structural improvement and optimization of cleaning device for rapeseed combine harvester. |
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