Development Of One-Step Centralized Type Pneumatic Seeding System

At present, most of seedmeters belong to "one seedmeter to one row" type. If increasing the work speed, the seeding environment will be damaged and the seeding quality will be lowered. If enlarging the cultivation breadth, many seedmeters will be demanded, which results in a complicated machine construction and is disadvantageous to develop the breadth cultivation and the cultivation-sowing combination work. The one-step centralized type pneumatic seeding system can realize the "one seedmeter to many rows" precise seeding by the ejection and mix of the ejector and the distribution of the allotor. It can predigest the seedmeter configuration, enhance the work efficiency many times and create the conditions for the precise seeding.The primary issues were researched as follows:(1) The design of the rational seedmeterWe chose a fluted feed as the rational seedmeter. Considering one seedmeter provides seeds to 10 seed tube synchronously, so we could not choose the feed roller's work length according to the traditional theory. In order to satisfy the big planting quantity, we designed the feed roller's work length from 60 mm to 80mm.(2) The design of the ejectorWe utilized the interrelated theories and calculation formulas of the gas ejector, got four speed coefficients, then the calculating result is near to the actual. The optimal section ratio and the optimal distance between the nozzle and the mixing chamber kept the best work state, boosted the energy exchange between the gas and the solid.(3) The design of the allotorTo reduce the pressure loss, a allotor with the compact layout and small cavity area was designed. The leading slices eliminated the seeding blind area and led seeds to enter seed tubes. The diffluence taper was designed according to the conclusion of the angle of reflection is bigger than the angle of incidence when hit, when hit the taper, seeds entered into seed tubes by the rebound. In addition, when calculated the pressure loss, we predigested its configuration, regarding it as a complex unit, which is composed of ten separate slantwise pipelines, and then formulas can be used.(4) The design of the conveying pipelines and its pressure loss calculation By making the aerodynamics analysis of seeds in pipelines, we got itsdifferential equations and its material-air speed ratios, calculated its pressure loss. We choosed the short radius siphon, but its pressure loss and its influence to the seed conveying need to be tested by the tests.Based on the essential calculation, the confirmation of the collectivity scheme, configuration design and parameters decision, the trial-manufacture, assembly, debugging and performance test had been done. The research result showed that:(1) The one-step centralized type pneumatic seeding system can substitute the traditional seedmeters. It can't only improve the work efficiency multiple times, predigest the configuration of the seeder, but also can suit to the high-speed work.(2) If choose the long radius siphon and the allotor without the diffluence taper, we got a aberrance coefficient ï¿¡=7.2%. If choose the short radius siphon and the allotor had the diffluence taper, we got a aberrance coefficientï¿¡=11.4%. In addition, the seeding quantity of the long radius siphon is bigger than that of the short radius siphon, which can prove that the conveying performance of the long radius siphon is better than that of the short radius siphon.(3) Because some parameters of the ejector and the allotor were not able to get its optimal value, the air and seeds could not get even mix, which led to the bigger variance coefficient.(4)The innovation facetsIn the allotor,the leading slices reduced the seeding blind area, the diffulence taper boosted the uniformity of the seeds distribution,was designed.all these measures kept the lower aberrance coefficient.During the test, the ejector is innovated, the mix chamber was substituted by the conveying pipelines, which can enhance the chamber length, advanced its mix capability, and also shortened the conveying distance, reduced the pressure loss.