气力辅助式对种穴施肥装置设计与试验

Design and Experiment of Pneumatic Assisted Hole Fertilization Targeting Seed Position Device

摘要:

针对玉米播种同步穴施肥过程中存在种-肥施用位置和施肥量不精准、穴施肥装置施肥成穴性较差等问题，设计一种气力辅助式对种穴施肥装置。依据检测的落种信号，气力辅助式间歇排肥装置将从外槽轮式排肥器排出的连续肥料转换为间歇肥团，并施用在距种子一定位置处。阐述该装置结构组成和工作原理，对其中关键结构尺寸进行理论分析，分析气流对挡板的作用，验证该装置的理论可行性。基于STM32单片机开发气力辅助式对种穴施肥控制系统，依据气力辅助式对种穴施肥工作方式，构建适用于高频间歇施肥场景的对种穴施肥控制模型，并设计硬件电路和控制程序。基于EDEM离散元进行仿真试验，结果表明，当前进速度为3~7km/h、穴距为300mm时，平均施肥长度为69.8~169.1mm，施肥长度变异系数为3.9%~11.9%，排肥量误差为1.7%~5.5%。通过观察仿真过程中气力辅助式间歇排肥装置内部肥料运动状态，确定挡板开启持续时间为100ms时排肥效果最佳。台架试验结果表明，单独穴施肥时平均施肥长度为75~187mm，施肥长度变异系数为5.3%~12.4%，排肥量误差为5.6%~12.8%，穴距误差为2.5%~6.5%。对种穴施肥结果，平均种-肥纵向间距为14~113mm。田间试验结果表明，当施肥量为5g/穴时，平均施肥长度为93~189mm，平均种-肥纵向间距为34~119mm，种-肥同步性较好，满足玉米播种同步穴施肥作业要求，试验结果与仿真试验值和台架试验值基本一致，验证了仿真试验和台架试验的可靠性。

Abstract:

Aiming at the maize sowing synchronous hole fertilization process exists in the seed-fertilizer application position and the amount of fertilizer application is not accurate, poor hole formation of fertilizer by hole application devices and other difficult problems, a kind of pneumatic assisted hole fertilization targeting seed position device was designed. Based on the detected seed drop signal, the pneumatic assisted intermittent fertilizer discharge device converted the continuous fertilizer discharged from the outer chute wheel fertilizer discharger into intermittent fertilizer mass and applied it at a certain position from the seed. The structural composition and working principle of the device were described, the key structural dimensions of which were theoretically analyzed, and the role of airflow on the baffle was analyzed to verify the theoretical feasibility of the device. Based on STM32 microcontroller, a pneumatic assisted hole fertilization targeting seed position control system was developed. Based on the working mode of pneumatic assisted hole fertilization targeting seed position, a hole fertilization targeting seed position control model applicable to high frequency intermittent fertilizer application scenario was constructed, and the hardware circuit and control program were designed. In order to study the performance of hole formation and fertilizer discharge stability of pneumatic assisted intermittent fertilizer discharge device, a discrete element simulation test was conducted based on EDEM. When the forward speed was 3~7km/h, the average length of fertilizer application was 69.8~169.1mm, the coefficient of variation of fertilizer application length was 3.9%~11.9%, and the error of fertilizer discharge ranged was 1.7%~5.5%. By observing the movement state of fertilizer inside the pneumatic assisted intermittent fertilizer discharge device during the simulation process, it was determined that the fertilizer discharge effect was the best when the baffle opening duration was 100ms. Bench test was carried out, the average length of fertilizer applied in individual holes was 75~187mm, the coefficient of variation of fertilizer length was 5.3%~12.4%, the error of fertilizer discharge was 5.6%~12.8%, and the error of hole spacing was 2.5%~6.5%. When targeting seed position hole application was carried out, the average seed-fertilizer longitudinal spacing was 14~113mm. The field experiment results showed that the average fertilization length was 93~189mm and the average seed-fertilizer longitudinal spacing was 34~119mm when the fertilizer amount was 5g/hole. Seed-fertilizer synchronization was good, meeting the maize sowing synchronous hole fertilization operation requirements. The test results were basically consistent with the simulation experiment and the bench test, which verified the reliability of the simulation experiment and the bench test.