平面四杆机构的运动分析

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平面四杆机构的运动性能研究

摘要：平面四杆机构是主要的常用基本机构之一,应用十分广泛,也是其他多杆机构的基础。由于连杆机构的性能受机构上繁多的几何参数的影响,呈复杂的非线性关系,无论从性能分析上还是性能综合上都是一个比较困难的工作,尚需作进一步深入研究。本文基于平面四杆机构的空间模型,将机构实际尺寸转化为相对尺寸,在有限的空间内表示出无限多的机构尺寸类型,从而建立起全部机构尺寸类型和空间点位的一一对应关系,为深入研究平面四杆机构的运动性能与构件尺寸之间的关系提供了基础。根据曲柄摇杆机构、双曲柄机构、双摇杆机构、单滑块四杆机构的不同特点,详细分析各类机构的运动性能参数与构件尺寸之间的关系,指出构件尺寸的变化对机构运动性能的影响,并绘制相关的运动性能图谱。针对具有急回特性的Ⅰ、Ⅱ型曲柄摇杆机构,通过深入分析极位夹角与构件尺寸之间的内在关系,获得了Ⅰ型曲柄摇杆机构极位夹角分别小于、等于或大于90°的几何条件以及Ⅱ型曲柄摇杆机构极位夹角一定小于90°的结论,揭示了曲柄摇杆机构设计时作为已知条件的极位夹角和摇杆摆角之间应满足的要求。本文得出的图谱和相关结论,为工程应用中机构性能分析和机构综合提供了理论依据。

关键词：平面四杆机构空间模型运动性能

Plane four clubs institutions of Sports performance research Abstract:The planar four-bar linkages are one type of basic mechanisms, and they are applied very extensively. The performances of the linkages depend on their geometrical parameters and present the complicated non-linear relations. It is necessary to make the further research on them for analysis, synthesis and application of linkages.By using of the three-dimensional models of the planar four-bar mechanisms, the actual sizes of mechanisms are transformed relative ones, and all size types of mechanisms can be figured by spatial coordinates. It is the foundation for research on the relations between the link dimensions and kinematic capability parameters.Aimed at the different characteristics of crank-rocker mechanism, double-crank mechanism, double-rocker mechanism and single-slider mechanism, some inherent relations between the link dimensions and the kinematic capability parameters are deeply analyzed, then the relative kinematic capability diagrams are obtained.Based on deeply analysis of inherent relations between the extreme position angle and the link dimensions of typeⅠand typeⅡcrank-rocker mechanisms with quick return characteristics, the geometrical conditions are put forward in this paper, by which we can judge whether the extreme position angle of typeⅠcrank-rocker mechanisms is less than, equal to or lager than 90°. It is proved that the extreme position angle of typeⅡcrank-rocker mechanism is certainly less than 90°. The relations between the extreme position angle and the angular stroke of the rocker are brought to light, which should be satisfied during the kinematic design of crank-rocker mechanisms.The diagrams and conclusions obtained in this paper provide theoretic foundation for the capability analysis and synthesis of mechanisms.

Keyword:Planar four-bar linkage Space model Sports Performance

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目录

1 序言

1.1 连杆机构 (1)

1.2 平面连杆机构运动学分析 (2)

1.3 本论文所作的主要工作 (3)

2 平面四连杆机构的类型

2.1 分类概念 (3)

2.2 分类 (4)

3 平面四杆机构运动分析

3.1.1 连杆上任意点的轨迹分析 (6)

3.1.2 Non-grashof机构的运动分析 (8)

3.2 速度分析 (9)

3.3 加速度分析 (10)

4 平面连杆机构曲线分类基准及分类

4.1 曲率 (11)

4.2 弧长 (12)

4.3 回转数 (12)

4.4 结点 (13)

4.5 变曲点、曲率极大点与极小点 (19)

4.6 机构数据库的建立 (20)

4.7 连杆曲线的分类结果 (20)

5 平面连杆机构的仿真设计

5.1 初始运行界面及程序 (23)

5.2 部分仿真结果 (42)

结论 (49)

参考文献 (51)

致谢 (52)