大籽粒作物漏播自补种装置设计与试验

针对大籽粒作物精量播种机普遍存在漏播现象,改进现有排种与补种相互独立的补种位置不准确等问题,提出了一种基于超越离合器的大籽粒作物漏播自补种方法,采用激光光电传感器和霍尔传感器分别监测漏种和排种器速度,依靠排种器自身的超越旋转实现位置无偏差补种并能够故障报警,并设计制作了排种与补种一体化的漏播自补种试验装置。试验结果表明,排种速度2~5 km/h、连续漏播数≤3粒时,补种时间间隔误差≤1.37%,补种粒距合格指数为100%,合格粒距变异系数≤14.48%,平均成功补种率为92.98%,综合漏播率≤0.8%,播种率达到99.2%。该研究可为大籽粒作物精量播种机改进设计提供参考。

Design and experiment of automatic reseeding device for miss-seeding of crops with large grain

Abstract: The loss sowing phenomenon is common for sowers for crops with large grain. Reseeding and seed-metering devices now available are independent of each other. This method has some problems such as reseeding inaccurately. In order to solve these problems, an automatic reseeding method based on an overrunning clutch was proposed in this paper. An automatic reseeding device that was composed of both a reseeding device and a seed-metering device was designed. The device adopted a hall sensor to get the speed of the seed-metering device. The hall sensor got the time interval between every two seed spoons of the seed-metering device to calculate the real-time speed of the seed-metering device. A laser sensor was used to monitor the loss of seeds. Seeds in the plate of the seed-metering device could block the light propagation path of the laser. If the light propagation path of the laser was not blocked, the seed was lost. An overrunning clutch was used to connect a step motor and the axle of the seed-metering device. The step motor was used to drive the seed-metering device to reseed with high speed. The overrunning clutch is a kind of compound function bearing which transmits torque between the inside hub and outside hub in one direction and allows free overrun in the opposite direction. It was used to switch torque source between the wheels of the seed-metering device and the step motor. The torque source came from the wheels of the seed-metering device when seeding but from the step motor when reseeding. When the laser sensor monitored the loss of seeds, the controller calculated the rotational speed and angle of the step motor based on the real-time speed of seeding and position of the missing seeds. The step motor drove the seed-metering device to reseed with a higher speed than seeding speed. The subsequent seed was added to the vacant position quickly. The system of the automatic reseeding device would give failure warnings to the user if the seed-metering device has a breakdown. Experiments show that when the seeding speed is between 2 km/h and 5 km/h and the continuous missing seeds number is less than 3, the error of the reseeding time interval increases as the seeding speed and the continuous missing seeds number increase. However, the maximum relative error of the reseeding time interval is less than 1.37%. The automatic reseeding device has a good performance of reseeding timeliness. The failure warning system of the automatic reseeding device can warn users of the failure of the seed-metering device accurately. The accuracy of the failure warning is 100%. The qualified index of seeding space is 100%. The variation rate of seeding space is 14.48%. Both of the qualified index of seed space and the variation rate of seed space are much better than the performance indicators of precision seeders in Chinese standard. The reseeding accuracy of the automatic reseeding device is high. The average rate of successful reseeding is 92.98%, the comprehensive missing rate decreases to 0.8%, and the sowing rate increases to 99.2%. The automatic reseeding device has a good effect. The study can provide a reference to improve the design of the precise seeder for large grains.