低压腔涡旋压缩机止推轴承润滑特性数值分析
发布时间：2018-09-17 09:39
【摘要】：能源危机的日益加剧,以及全球气候不断变暖的趋势正在深刻改变人们的生活方式,人们越来越意识到节约能源和减少能耗对改善地球生态环境的重要性。涡旋压缩作为一种新型制冷压缩机,以其高效率、低噪音、运转稳定以及关键零部件少等优点而受到空调市场上的广泛关注。自从上世纪80年代涡旋压缩机首先被应用到商用空调上以来的三十多年间,对涡旋压缩机性能的研究日益广泛深入。在涡旋压缩机中,止推轴承主要是用来平衡气体介质在压缩过程中产生的轴向气体力,由于滑动止推轴承具有良好的轴向承载力和低摩擦特性而在生产实际中被广泛采用。低压腔涡旋压缩机止推轴承是由动涡旋盘背面和支架体上表面构成。动涡旋盘公转过程中,动涡旋盘受到的切向气体力、径向气体力以及本身由于偏心旋转运动而产生的离心力并未与动涡旋盘驱动平面共面,由此形成了一个使动涡旋盘发生倾覆的倾覆力矩。动涡旋盘的倾覆可以使止推轴承产生几何楔形,楔形的几何形状有利于润滑油膜因动压效应而产生油膜压力,动压油膜的形成可以有效平衡轴向力,因此对止推轴承润滑性能的理论分析很有必要。本文主要研究动涡旋盘受到倾覆力矩的作用使止推轴承承压面产生倾斜而引起的止推轴承润滑特性产生变化问题。首先通过对止推轴承止推合力以及倾覆力矩的分析以及雷诺方程的建立,并利用数值方法求解了雷诺方程、油膜形成的合力、力矩与止推轴承受到的力、力矩组成的非线性方程组。在一个循环周期内,分析了止推轴承处油膜压力以及油膜厚度分布情况,以及中心油膜厚度、动涡旋盘倾斜角和倾斜方位角的变化情况。在此基础上,研究了主轴转速对止推轴承润滑特性的影响,并分析了止推合力在止推轴承径向的位置变化时对动压油膜形成的影响。研究结果表明:油膜压力主要分布在动涡旋盘倾斜收敛区域,并呈U形形状分布。主轴旋转一周,U形动压油膜随主轴的变化交替出现在止推轴承不同位置处,这预示着动压油膜可以在止推轴承上开设的环形油槽里顺畅流动,减少了润滑油的泄漏,而且最大油膜压力、中心油膜厚度和动涡旋盘倾斜角随主轴改变并不明显。其次,研究表明只有当止推合力处在一定径向范围内时,数值求解过程中才能得到收敛解,而当止推合力超出这一范围时,动压油膜有可能不能正常形成,这会造成止推轴承金属与金属之间的直接接触,磨损或者不稳定现象的发生。最后通过对涡旋压缩机结构参数进行优化设计以此来改善止推轴承的润滑情况。
[Abstract]:With the worsening of the energy crisis and the trend of global warming, people are becoming more and more aware of the importance of energy conservation and energy consumption in improving the ecological environment of the earth. Vortex compression, as a new type of refrigeration compressor, has attracted wide attention in the air conditioning market because of its high efficiency, low noise, stable operation and few key parts. Since the scroll compressor was first applied to commercial air conditioning in the 1980s, the research on the performance of scroll compressor has been more and more extensive. In scroll compressors, thrust bearings are mainly used to balance the axial gas force produced by gas medium during compression. Sliding thrust bearings are widely used in production because of their good axial bearing capacity and low friction characteristics. The thrust bearing of the low-pressure cavity scroll compressor is composed of the back of the moving scroll disk and the upper surface of the bracket. The tangential gas force, the radial gas force and the centrifugal force caused by the eccentric rotating motion are not coplanar with the driving plane of the moving vortex disk. Thus a capsizing moment is formed to overturn the moving vortex disk. The overturning of the dynamic scroll disk can make the thrust bearing produce geometric wedge. The geometric shape of the wedge is favorable to the oil film pressure caused by the dynamic pressure effect. The formation of the dynamic pressure oil film can effectively balance the axial force. Therefore, it is necessary to analyze the lubrication performance of thrust bearing. In this paper, the lubricating characteristics of thrust bearings caused by the tilting of the bearing due to the overturning moment of the dynamic vortex disk are studied. Firstly, through the analysis of thrust force and overturning moment of thrust bearing and the establishment of Reynolds equation, the resultant force of oil film formation, the force of torque and thrust bearing are solved by numerical method. Nonlinear equations of moment composition. The oil film pressure and oil film thickness distribution at the thrust bearing, the variation of the central oil film thickness, the tilt angle and the tilt azimuth angle of the moving vortex disk are analyzed in a cycle. On this basis, the influence of spindle speed on the lubrication characteristics of thrust bearing is studied, and the influence of thrust force on the formation of hydrodynamic oil film is analyzed when the thrust force changes in the radial position of thrust bearing. The results show that the oil film pressure is mainly distributed in the inclined convergent region of the moving vortex disk, and the oil film pressure is distributed in the shape of U shape. The oil film of U-shaped dynamic pressure appears alternately in different positions of thrust bearing with the change of spindle around the spindle, which indicates that the oil film of dynamic pressure can flow smoothly in the annular oil tank set up on the thrust bearing, thus reducing the leakage of lubricating oil. Moreover, the maximum oil film pressure, the thickness of the central oil film and the tilting angle of the moving vortex disk do not change significantly with the spindle. Secondly, it is shown that only when the thrust force is in a certain radial range, the convergence solution can be obtained in the numerical solution process, but when the thrust force exceeds this range, the dynamic pressure oil film may not be formed normally. This can lead to direct contact, wear or instability between thrust bearing metals and metals. Finally, the lubrication of thrust bearing is improved by optimizing the structure parameters of scroll compressor.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB652
本文编号：2245470
[Abstract]:With the worsening of the energy crisis and the trend of global warming, people are becoming more and more aware of the importance of energy conservation and energy consumption in improving the ecological environment of the earth. Vortex compression, as a new type of refrigeration compressor, has attracted wide attention in the air conditioning market because of its high efficiency, low noise, stable operation and few key parts. Since the scroll compressor was first applied to commercial air conditioning in the 1980s, the research on the performance of scroll compressor has been more and more extensive. In scroll compressors, thrust bearings are mainly used to balance the axial gas force produced by gas medium during compression. Sliding thrust bearings are widely used in production because of their good axial bearing capacity and low friction characteristics. The thrust bearing of the low-pressure cavity scroll compressor is composed of the back of the moving scroll disk and the upper surface of the bracket. The tangential gas force, the radial gas force and the centrifugal force caused by the eccentric rotating motion are not coplanar with the driving plane of the moving vortex disk. Thus a capsizing moment is formed to overturn the moving vortex disk. The overturning of the dynamic scroll disk can make the thrust bearing produce geometric wedge. The geometric shape of the wedge is favorable to the oil film pressure caused by the dynamic pressure effect. The formation of the dynamic pressure oil film can effectively balance the axial force. Therefore, it is necessary to analyze the lubrication performance of thrust bearing. In this paper, the lubricating characteristics of thrust bearings caused by the tilting of the bearing due to the overturning moment of the dynamic vortex disk are studied. Firstly, through the analysis of thrust force and overturning moment of thrust bearing and the establishment of Reynolds equation, the resultant force of oil film formation, the force of torque and thrust bearing are solved by numerical method. Nonlinear equations of moment composition. The oil film pressure and oil film thickness distribution at the thrust bearing, the variation of the central oil film thickness, the tilt angle and the tilt azimuth angle of the moving vortex disk are analyzed in a cycle. On this basis, the influence of spindle speed on the lubrication characteristics of thrust bearing is studied, and the influence of thrust force on the formation of hydrodynamic oil film is analyzed when the thrust force changes in the radial position of thrust bearing. The results show that the oil film pressure is mainly distributed in the inclined convergent region of the moving vortex disk, and the oil film pressure is distributed in the shape of U shape. The oil film of U-shaped dynamic pressure appears alternately in different positions of thrust bearing with the change of spindle around the spindle, which indicates that the oil film of dynamic pressure can flow smoothly in the annular oil tank set up on the thrust bearing, thus reducing the leakage of lubricating oil. Moreover, the maximum oil film pressure, the thickness of the central oil film and the tilting angle of the moving vortex disk do not change significantly with the spindle. Secondly, it is shown that only when the thrust force is in a certain radial range, the convergence solution can be obtained in the numerical solution process, but when the thrust force exceeds this range, the dynamic pressure oil film may not be formed normally. This can lead to direct contact, wear or instability between thrust bearing metals and metals. Finally, the lubrication of thrust bearing is improved by optimizing the structure parameters of scroll compressor.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB652
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