气流辅助高速投种精量播种机压种装置设计与试验

Design and Experiment of Seed Pressing Device for Precision Seeder Based on Air Flow Assisted Seed Delivery

气流辅助高速投种能够减小种子在导种管内因与管壁碰撞而产生的株距变异,但气流作用增大了种子落地的初速度,导致落地后弹跳对株距均匀性产生影响。为此,设计了一种适于气流辅助高速投种的精量播种机压种装置,在种子落地时,利用压种轮与土壤双向挤压作用实现种子精准定位。将压种装置安装在大豆精量播种机上进行了田间试验,结果表明,作业速度、导种管末端与压种轮的水平距离对株距合格指数、变异系数影响均显著,种子投射角对株距合格指数影响不显著、对株距变异系数影响显著。采用压种轮、压种舌和无压种条件下的对比试验表明,压种轮能够显著减少种子落地弹跳,采用压种轮的株距合格指数、变异系数明显优于采用压种舌和无压种条件,压种轮最优工作参数组合为作业速度9.5 km/h、投射角30°、导种管末端与压种轮的水平距离75 mm,在此工作条件下株距合格指数、变异系数分别为95.68%、10.32%。

The high speed operation is the development trend of precision seeding.Air flow assisted seed delivery can reduce the variation of plant spacing caused by the collision of seeds with the pipe wall and meet the requirements of high-speed operation.However,the air flow also accelerates seeds during delivery.Seeds with high speed tend to bounce after landing,which resulting in uneven plant spacing.Aiming at the above problems,a seed pressing device suitable for precision seeder with air flow assisted seed delivery was designed.The seed pressing device was installed behind the seed delivery tube on the seeder unit.When the seed fell to the ground,it was pressed by the squeezing action between the pressing wheel and the soil to avoid the seed jump and realize the accurate plant spacing.The seed pressing device was installed on the soybean precision seeder for field test,and the theoretical plant spacing was set to be 10 cm.The orthogonal test was carried out,and the factors were operating speed,horizontal distance between the end of the seed delivery tube and the pressing wheel,and projection angle of seed at the end of delivery tube.The test indexes were plant spacing qualification index and variation coefficient.The results showed that the operating speed,the horizontal distance between the end of the delivery tube and the pressing wheel had impact on the plant spacing qualification index and variation coefficient,while the projection angle had no significant impact on the plant spacing qualification index and significant impact on the plant spacing variation coefficient.At the same time,the comparison experiment was carried out under the conditions of seed pressing wheel,seed pressing tongue and no seed pressing.The results showed that the uniformity of plant spacing of seed pressing tongue and seed pressing wheel was better than that of no seed pressing operation,while the seed pressing wheel was better than the seed pressing tongue.This showed that the seed pressing wheel can significantly reduce seed bounce and had the ability to obtain the uniform plant spacing.For the seed pressing wheel,the plant spacing qualification index and coefficient of variation were significantly better than those under the conditions of seed pressing tongue and no pressing.The optimal working parameters of the seed pressing wheel were the working speed of 9.5 km/h,the projection angle of 30°,and the horizontal distance between the end of the delivery tube and the pressing wheel of 75 mm.Under these working conditions,the plant spacing qualification index and coefficient of variation were 95.68%and 10.32%,respectively.The research result can provide theoretical basis and technical support for solving the uneven planting space under the condition of air flow assisted seed delivery.