正负气压组合槽孔轮式小麦排种器设计与试验

Design and Experiment of Positive and Negative Air Pressure Combined Grooved Hole Wheel Metering Device for Wheat

摘要:

针对传统小麦排种器能耗高、卸种不畅及充种稳定性不足等问题，设计了一种正负气压组合槽孔轮式小麦排种器。该排种器以"负压吸种+槽轮辅助充种+正压卸种"为核心工作原理，通过在排种轮表面设置凸包槽孔结构以增强种群扰动，提高充种稳定性，并在投种区引入正压气流实现辅助卸种。通过理论分析构建了吸种、携种、投种阶段种子力学模型，明确了排种轮转速、负压、型孔尺寸等关键参数对排种性能的影响机制;基于EDEM软件分析了槽孔轮、凸包槽孔轮和窝眼轮对种群扰动的效果，确定凸包槽孔轮为最优选择，其种群平均动能达6.6×10^-9 J，较窝眼轮提升4.4倍;利用CFD软件优化型孔直径组合，当排种轮1型孔直径为1.6 mm、排种轮2型孔直径为1.8 mm时，型孔气流速度变异系数最低（2.13%），气流分布最均匀。台架试验结果表明，在最优参数组合为转速30 r/min、负压2.5 kPa时，平均排量为157.47 g/min，各行排量一致性变异系数（RCV）为2.46%，总排量稳定性变异系数（TCV）为1.09%，满足精量播种标准。田间试验测得各行株数一致性变异系数为11.22%，排种均匀性良好。研究结果可为小麦低能耗高稳定性精量排种装置设计提供参考。

Abstract:

Aiming to address the problems of high energy consumption, poor seed discharge, and insufficient seed-filling stability in traditional wheat seed metering devices, a positive and negative air pressure combined grooved hole wheel metering device was designed.The device operated based on the principle of "negative-pressure seed suction+auxiliary seed filling by a slotted wheel+positive-pressure seed discharge".A convex slotted-hole structure was arranged on the surface of the seed metering wheel to enhance seed group disturbance and improve seed-filling stability, while positive airflow was introduced in the seed release zone to assist seed discharge.A mechanical model of seed motion during the seed suction, seed carrying, and seed release stages was established through theoretical analysis, and the influence mechanisms of key parameters, including seed metering wheel rotational speed, negative pressure level, and hole size on seeding performance were clarified.Based on EDEM simulation, the disturbance effects of a slotted-hole wheel, convex slotted-hole wheel, and cell wheel on the seed population were compared.The results showed that the convex slotted-hole wheel was the optimal structure, with an average seed-group kinetic energy of 6.6×10^-9 J, which was 4.4 times higher than that of the cell wheel.CFD simulation was used to optimize the hole diameter combination.When the diameter of type-Ⅰ holes on seed metering wheel 1 was 1.6 mm and that of type-Ⅱ holes on seed metering wheel 2 was 1.8 mm, the airflow velocity coefficient of variation reached the minimum value of 2.13%, indicating the most uniform airflow distribution.Bench test results showed that under the optimal parameter combination of a rotational speed of 30 r/min and a negative pressure of 2.5 kPa, the average seeding rate was 157.47 g/min, the row coefficient of variation of seeding rate (RCV) was 2.46%, and the total coefficient of variation of seeding rate (TCV) was 1.09%, meeting the requirements of precision seeding standards.Field test results indicated that the consistency variation coefficients of the number of plants per row was 11.22%, demonstrating good seeding uniformity.The results can provide a reference for the design of low-energy-consumption and high-stability precision seed metering devices for wheat.