涡旋压缩机曲轴部件静动态性能研究及优化

发布时间：2019-03-25 14:02

【摘要】：涡旋压缩机以噪音低、效率高、结构紧凑、零件数目少且运转平稳等特点,广泛应用于汽车空调、制冷、发动机增压以及真空泵等行业。涡旋压缩机的主要零件包括动涡旋盘、静涡旋盘、曲轴、平衡铁、机架、轴承和防自转机构等,它们的受力和工作状况将直接或间接地影响压缩机的效率及稳定性。因此对核心零部件力学特性的研究分析和相关优化显得尤为重要,也是确保涡旋压缩机性能和可靠性的前提。针对这种情况,本文以某涡旋压缩机虚拟样机的曲轴和曲轴部件作为研究对象,通过有限元分析ANSYS Workbench平台对曲轴和曲轴部件在工作过程中的静动态力学特性做研究分析,并对曲轴上滑动轴承与角接触球轴承之间的距离、曲轴的轴径和轴长进行优化。具体的研究内容主要包括下面几点:(1)根据涡旋型线的啮合原理和法向等距曲线理论,设计了变截面动涡旋盘的型线,同时根据涡旋盘的型线方程和基本参数计算动涡旋盘在工作过程中所受的气体力(法向气体力rF和切向气体力tF)。(2)建立曲轴-轴承系统的有限元模型,将轴承简化为不同数目的均布弹簧,从而探究分析弹簧的数目及位置对曲轴径向刚度的影响;然后将最大气体力作为静态载荷,施加在曲轴的偏心段中心位置模拟分析曲轴-轴承系统在静态载荷下的应力和变形,并计算曲轴的静刚度,为曲轴-轴承系统的优化结果作对比提供参考依据。(3)对曲轴和曲轴部件的动态特性作仿真研究。首先进行模态分析,得到曲轴和曲轴部件两种结构下的前6阶固有频率、振型及振动特性,发现其前6阶固有频率都较高,从而说明曲轴和曲轴部件在实际的激振频率下都不易发生共振并探究影响曲轴固有频率的因素;同时在模态分析基础之上对曲轴和曲轴部件上的不同位置做谐响应分析,得到应力和位移随频率变化的特性,并对其进行比较分析。(4)通过分别优化轴承之间的跨距l、曲轴的轴径1R、轴长1l,并对跨距l、轴径1R和轴长1l进行多目标参数优化,从而减小曲轴偏心段的最大挠度,使得曲轴的径向静刚度有所提高;通过上述的优化设计使得曲轴部件具有更好的静动态性能,从而减小动涡旋盘与静涡旋盘之间的摩擦使动静涡旋盘的啮合更加平稳有效,并提高轴承的使用寿命。
[Abstract]:Because of its low noise, high efficiency, compact structure, small number of parts and stable operation, scroll compressor is widely used in automotive air conditioning, refrigeration, engine pressurization and vacuum pump industries. The main parts of scroll compressor include moving vortex disk, static vortex disk, crankshaft, balance iron, frame, bearing and anti-rotation mechanism, etc. Their force and working condition will directly or indirectly affect the efficiency and stability of the compressor. Therefore, it is very important to study and analyze the mechanical characteristics of the core parts and optimize them, and it is also the premise to ensure the performance and reliability of the scroll compressor. In view of this situation, the crankshaft and crankshaft parts of a virtual prototype of a scroll compressor are studied in this paper, and the static and dynamic mechanical characteristics of crankshafts and crankshaft components in the working process are studied and analyzed by finite element analysis (ANSYS Workbench) platform. The distance between journal bearing and angular contact ball bearing on crankshaft, shaft diameter and shaft length of crankshaft are optimized. The main contents of the research are as follows: (1) according to the meshing principle of vortex profile and the theory of normal equidistant curve, the profile of dynamic vortex disk with variable cross-section is designed. At the same time, the finite element model of crankshaft-bearing system is established according to the profile equation of the vortex disk and the basic parameters to calculate the gas force (the normal gas force rF and the tangential gas force tF). (2) during the working process of the moving vortex disk, and at the same time, the finite element model of the crankshaft-bearing system is established. The bearing is simplified to different number of uniformly distributed springs, and the influence of the number and position of springs on the radial stiffness of crankshafts is investigated. Then the maximum gas force is taken as static load, and the stress and deformation of crankshaft-bearing system under static load are simulated and analyzed at the center of eccentric section of crankshaft, and the static stiffness of crankshaft is calculated. It provides a reference for the comparison of the optimization results of crankshaft-bearing system. (3) the dynamic characteristics of crankshaft and crankshaft components are simulated. First, the first six natural frequencies, mode shapes and vibration characteristics of crankshaft and crankshaft components are obtained by modal analysis. It is found that the first six natural frequencies of crankshaft and crankshaft components are higher than those of crankshaft components. This shows that the crankshaft and the crankshaft components are not easy to resonate under the actual excitation frequency and explore the factors that affect the natural frequency of the crankshaft. At the same time, on the basis of modal analysis, harmonic response analysis of different positions on crankshaft and crankshaft components is carried out, and the characteristics of stress and displacement varying with frequency are obtained and compared. (4) the span between bearings is optimized respectively. The maximum deflection of eccentric section of crankshaft is reduced, and the radial static stiffness of crankshaft is improved by optimizing the multi-objective parameters of span 1, shaft diameter 1R and shaft length 1l, and the axial diameter 1R and shaft length 1l of crankshaft are optimized in order to reduce the maximum deflection of eccentric section of crankshaft and improve the radial static stiffness of crankshaft. Through the above optimization design, the crankshaft parts have better static and dynamic performance, thus reducing the friction between the dynamic vortex disk and the static vortex disk, making the meshing of the dynamic and dynamic vortex disk more stable and effective, and prolonging the service life of the bearing.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TH45

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