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目录
摘 要 1
ABSTRACT 2
第一章 绪论 3
1.1 研究小颗粒种子精播技术的目的和意义 3
1.2 国内外气力式精密排种器的发展概况 3
1.2.1 国外气力式排种器的发展概况 4
1.2.2 国内气力式排种器的发展概况 4
1.3 本文研究的内容 5
第二章 气吸滚筒式精密排种器的优化设计 6
2.1 排种器结构及工作原理 6
2.1.1 总体结构 6
2.1.2 工作原理 7
2.2.1 排种滚筒上吸孔的设计 8
2.2.2 排种滚简内部正负压腔的设计 8
2.3 排种装置的优化设计 10
2.4 本章小结 11
第三章 气吸滚筒式精密排种器的理论分析 12
3.1 种子所受吸附力及吸种高度的确定 12
3.1.1 吸附力及其影响因素 12
3.1.2 吸种高度及影响因素 13
3.2 气吸滚筒式精密排种器吸种过程及其影响因素的分析 16
3.2.1种子从种箱到被吸孔吸附过程分析 17
3.2.2 种子被吸附到滚筒上并随之运动的条件 19
3.3 气吸滚筒式精密排种器的排种过程分析 20
3.3.1 排种误差 20
3.3.2 种子落地碰撞角和碰撞速度 23
3.3.3 排种过程影响因素分析 24
3.4 本章小结 24
第四章 气吸滚筒式精密排种器气流场的计算机仿真 25
4.2  ANSYS仿真初始边界条件的设定 26
4.2.1 吸孔的结构形状及初始化条件 26
4.3 仿真结果 28
4.3.1 吸孔形状对吸种性能的影响 28
4.3.2 吸孔导程对吸种性能的影响 31
4.3.3 吸孔孔径大小对吸种性能的影响 32
4.3.4 吸种滚筒内部负压区气流场仿真 34
4.3.5 吸种滚筒内部正压区气流场仿真 36
4.4 本章小结 38
第五章 总结与展望 39
参考文献 41
致 谢 43

摘 要
世界各国都很重视精量播种技术，精密播种可以节约大量的种子，节省田间间苗定苗用工，增加作物产量。本文在对国内外现有的气吸滚筒式精密排种器深入研究的基础上，对原有的设计进行了改进并制造了一种新型的气吸滚筒式精密排种器。该排种器具有以下的特点:首先，对主轴结构进行了优化设计，采用了一根主轴形成两个压腔的设计方法，既保证了同轴度又减少了轴承的磨损，大大延长了轴承的使用寿命。其次，由于采用了弹簧结构，在隔气板与滚筒内壁接触转动的过程中，减少了因摩擦而导致的磨损漏气的问题。第三，对种箱进行了激振，使种子在种箱中形成“沸腾”状态，更有利于滚筒的吸种。
结合该气吸滚筒式精密排种器，本文主要开展了以下几个方面的研究工作:
1.对气吸滚筒式精密排种器的吸种及排种过程进行了理论分析，得到了吸附力、吸种高度、排种误差、碰撞角和碰撞速度等数学模型，并对影响吸排种效果的因素进行了分析。
2.运用ANSYS有限元分析软件对吸孔及正负压腔的气流场进行了建模与仿真试验，结果表明:直孔的吸种性能比锥形孔和沉孔好:孔径越大，吸种能力越强;吸孔导程对吸种性能无显著影响;滚筒壁上的吸孔靠近正负压腔气流大的地方，受到气流的影响也较大。
通过对气吸滚筒式精密排种器的理论分析和计算机仿真，得到了一些规律，为其实际应用奠定了基础。

关键词:精密播种;气吸滚筒式精密排种器;有限元分析;理论分析;

ABSTRACT
Precision seeding is attached importance to by all over the world,for it can save a lot of seeds and much time to plant them and increase the output.Basing on researching domestic and foreign air-suction cylinder precision seeder,a new type of air-suction cylinder precision seeder was designed and manufactured.There are some merits of the seeder:First,the main shaft with two cavums was optimized which reduced the abrasion and prolonged the life of the bearings.Second,the spring structure was adopted,so the gas leakage between the plastic board and the seeder's wall was eliminated because of friction.Third,the seeds box was vibrated that availed picking up seeds.
Basing on the air-suction cylinder precision seeder,the research was done as follows:
1. Seed pick up and seed ejection were theoretically analyzed and mathematical models of pick up force,pick up distance,release error,impact angle and impact velocity were deduced.
2. ANSYS finite element analysis software was used to develop the model and simulate the air flow distribution of the sucking holes,positive and negative cavums.The results showed that the performance of straight holes were better than conical holes and countersunk holes; the bigger of the diameter of the holes ,the better of their sucking effect, but the distance of air traveling had nearly no influence to sucking effect; the holes which were close to the air flow in the wall of the drum-seeder were influenced notably.
Through computer simulation and theoretical analysis,some laws useful for practical application were found.

KEY WORDS:Precision seeding; Air-suction cylinder precision seeder; Finite element analysis; Theoretical analysis;