| Rapeseed is widely grown in China.The main fertilization methods are shallow mixed application of granular fertilizer and artificial spreading fertilizer.Fertilizer application amount is large,on the one hand,resulting in fertilizer waste,on the other hand,resulting in environmental pollution.At the same time,the supporting fertilizer apparatus is single.In order to increase fertilizer efficiency and achieve the goal of green agriculture development,a precise discharge device of granular fertilizer is developed to meet the synchronous fertilization of rapeseed planting.According to the characteristics of granular fertilizer and the agronomic requirements of fertilization,a spiral disturbance cone centrifugal fertilizer apparatus with active anti-blocking function is innovatively designed to achieve smooth,uniform and stable fertilization.A speed-following fertilization control system based on high-precision speed radar is designed.And based on the root growth discipline and fertilizer requirement of rape,a stratified quantitative fertilization apparatus is designed.The contents and conclusions are as follows:(1)According to that requirements of the fertilize application amount of the rapeseed planting,taking the stability,the uniformity and the smoothness of distributing as targets,the design scheme of the fertilizer apparatus is determined,and the design principle and working principle of the spiral disturbance cone centrifugal fertilizer apparatus are described.Combined with the planting mode of rape sowing in line and the growth principle of rape root system,a technology based on the uniform distribution of fertilizer flow collision is proposed,in which the amount of fertilizer in the upper and lower layers is distributed proportionally and the fertilizer in the upper layer is applied separately from left to right.Meanwhile,a ratio-controlled layered quantitative fertilization apparatus is designed,and the dimensions of the components are determined.(2)The design analysis and performance test of the key components of the spiral disturbance cone centrifugal fertilizer apparatus are carried out.Based on the characteristics of fertilizer commonly used in rapeseed planter,the structural parameters of spiral disturbance cup and arc cone disc are determined.Taking Chinese agricultural compound fertilizer,Stanley compound fertilizer and Ezhong compound fertilizer as test materials,through bench test,the performance of fertilizer discharging at 80～130r/min is studied.The results show that the coefficient of variation of fertilizing amount consistency in every row is less than 11.5%,the coefficient of variation of fertilizing amount stability is less than 6.3%,and that of the coefficient of variation of fertilizing amount consistency in same row is less than 7% and 9.82% when the fertilizer apparatus is inclined.The results of the field experiment show that coefficient of variation of fertilizing amount consistency in every row is less than 7.9%,coefficient of variation of fertilizing amount stability is less than 5.3%,and coefficient of variation of fertilizing amount consistency in same row is less than 6.5%,which met the requirements of field fertilizer quality.(3)The motion model of granular fertilizer in the spiral disturbance cup is constructed,and the mechanism of arch breaking and anti-blocking of spiral disturbance blade is clarified.The fertilizer delivery process of the fertilizer apparatus with and without the spiral disturbance cup is simulated and compared by using the EDEM discrete element software.High-speed camera test shows that the granular fertilizer at the joint of the outlet of the bins and the spiral disturbance cup fertilizer apparatus moves to the lower right,and the granular fertilizer moves smoothly without fault falling.On the contrary,the granular fertilizer at the joint of the non-spiral disturbance cup fertilizer apparatus and the fertilizer outlet of the fertilizer box moves slowly downward,and there is a problem of intermittent falling of granular fertilizer during the movement.The results of bench test shows that the stability coefficient of fertilizer frequency is above 96%,and the variation coefficient of fertilizer quantity stability is less than 5.57%.The results meet the requirements of fertilizer quality and the spiral disturbance cup fertilizer apparatus is significantly better than that without spiral disturbance cup.(4)To further improve the comprehensive performance of the fertilizer apparatus,the parameter analysis and optimization of the arc cone and disc of the fertilizer apparatus are carried out.Through theoretical analysis,an arc cone and disk whose generatrix curvature decreases gradually from top to bottom is optimized,and the generatrix equation is determined.In This paper,the influence of different forms of fertilizer apparatus on the performance of fertilizer delivery are explored,and simulation comparison tests of the performance of three different forms of fertilizer apparatus are carried out by using the EDEM.The fertilizer performance of the optimized fertilizer apparatus is clearly superior to the other two types of fertilizer apparatus.The results of bench test shows that coefficient of variation of fertilizing amount consistency in every row is still less than 10.23%,the coefficient of variation of fertilizing amount stability is less than 6.74%,and the coefficient of variation of fertilizing amount consistency in same row is less than 3.52% when the optimized fertilizer dispenser is inclined at a larger angle and at a lower speed.(5)The movement model of granular fertilizer in the fertilizer apparatus is constructed,and the main structural parameters and ranges affecting the performance of the fertilizer apparatus are determined through theoretical analysis.The quadratic regression orthogonal rotation combination test are carried out,and the key parameters of fertilizer apparatus are determined as follows: the horizontal inclination angle is 30.4 °,the radial deflection angle of the push plate is 3.2°,and the rotating speed of the cone plate is 130r/min.Based on the optimal parameter combination of the fertilizer apparatus,the discharge capacity calibration and performance verification tests are carried out.The coefficient of variation of fertilizing amount stability is less than 4.56%,the coefficient of variation of fertilizing amount consistency in every row is less than 6.03%,and the coefficient of variation of fertilizing amount consistency in same row is less than 2.44%.The field experiment shows that the coefficient of variation of fertilizing amount consistency in every row is less than 6.98%,coefficient of variation of fertilizing amount consistency in same row is less than 3.36%,and coefficient of variation of fertilizing amount stability is less than 4.57%,which further improved the fertilizing performance.(6)According to the parameters of high-precision speed radar and the discharge of fertilizer device,combined with the relationship between the speed and discharge of fertilizer device,the control system of rapeseed direct seeding with speed fertilization is designed.The mathematical modeling of the permanent magnet DC motor is established,the transfer function of the control part is obtained,and the PD parameters are determined by using MATLAB-PD regulator.Based on the designed speed following control system,the performance test is carried out.The relative error between the target and the actual amount of fertilizer is less than 2.82% in the constant speed fertilizing performance,less than 2.67% in the road variable speed test,and less than 3.43% in the field test.The quality of the fertilizer discharge is met,indicating that the fertilizer application control system with speed has a high degree of control accuracy.(7)Based on the uniform distribution of granular fertilizer,the technology of proportional distribution of fertilizer in the upper and lower layers and separate application of fertilizer in both sides of the upper layer is proposed.At the same time a stratified quantitative fertilization device with controlled proportion is designed,and the state transition matrix is is constructed to verify the effect of uniform fertilizer distribution.Then,the basic parameters of the device are decided.The fertilizer uniform distribution device are determined as 3mm for the diameter of the stop bar,5 for the number of the stop bar groups,and 8.9mm for the distance between the stop bar groups.On the one hand,the experiment of fertilizing performance under the optimal parameter combination is carried out.The maximum error between the actual fertilization ratio of upper and lower layers and the target fertilization ratio is 4.1 percentage points,and the coefficient of variation of fertilizing stability is less than 3.9%.The error between the actual fertilization ratio and the target fertilization ratio in the upper and left fertilizer tubes is less than 4.1 percentage points,and the coefficient of variation of the stability of fertilizer delivery is less than 4.8%.The results meet the requirements of fertilizer application in proportion.On the other hand,the field experiment shows that the average depth of fertilizer application is 141.2mm in the lower layer,81.9mm in the left side of the upper layer,81.6mm in the right side,and the average distance between the left and right sides of the upper layer is 67.8mm,which meet the design requirements of rape layered fertilization. |
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