The Influence of the vane on the lubrication characteristics between the vane and the rolling piston of a rotary compressor

The rolling piston type rotary compressor has been widely used for refrigeration and air-conditioning systems due to its compactness and high-speed operation. The present analysis is part of a research program directed toward maximizing the advantages of refrigerant compressors. The study of lubrication characteristics in the critical sliding component is essential for the design of refrigerant compressors. Therefore, theoretical investigation of the lubrication characteristics of a rotary compressor being used for refrigeration and air-conditioning systems was investigated. The Newton-Raphson method was used for a partial elastohydrodynamic lubrication analysis between the vane and the rolling piston of a rotary compressor. The results demonstrated that the vane thickness and the center line position of the vane significantly influenced the friction force and the energy loss between the vane and the rolling piston.     

Lubrication characteristics of a rotary compressor used for refrigeration and air-conditioning systems (the influence of alternative refrigerants)

The rolling piston type rotary compressor has been widely used for refrigeration and air-conditioning systems due to its compactness and high-speed characteristics. However, it is necessary to develop alternative refrigerants that can guarantee environmental protection. In addition, advanced refrigerant compressors must be further developed to overcome the compatibility problems inherent in refrigeration and air-conditioning systems. The refrigerant compressor is the most important mechanical component, which determines the performances of refrigeration and air-conditioning systems. Therefore, we theoretically investigated the lubrication characteristics of the rotary compressor currently used in both refrigeration and air-conditioning systems with an alternative refrigerant. In the theoretical investigation, the Runge-Kutta method is used to analyze the behavior of a rolling piston in the rotary compressor. Subsequently, the Newton-Raphson method is used, which provided good performance in the analysis of the elastohydrodynamic lubrication of the line contacts between a rolling piston and a vane in the rotary compressor. The results demonstrate that the alternative refrigerants influence the friction force and the energy loss between the vane and the rolling piston.     

Friction and Wear Characteristics of TiN Coated Vane for the Rotary Compressor in a R410A Refrigerant©

HFC is a potential alternative refrigerant for CFC, which depletes the ozone layer. The rotary compressor has been widely used for refrigeration and air-conditioning systems due to its compactness and high-speed operation. R410A, an HFC refrigerant, is used in a refrigerator compressor, but its frictional characteristic is not established. In this study, the influence of R410A refrigerant on the roller-vane surfaces was studied, and friction and wear characteristics of the TiN coated vane were investigated. The friction and wear data were obtained with a specially designed high-pressure wear tester. A testing environment charged with HFC refrigerant more closely simulates the operating conditions of a real rotary compressor. In pure oil without R410A, wear of the TiN coated vane was larger than that of the uncoated vane. But when the refrigerant was dissolved in oil, wear of the uncoated vane was larger than that of the TiN coated vane. This showed that a TiN coated vane is good relative to wear resistance in the refrigerant/lubricant mixed environment. As the rotating speed of the frictional motion increased, wear increased. But in the high-velocity region, wear decreased because the boundary lubrication is changed into the mixed lubrication in the lubrication region. As the pressure grew larger, wear volume and coefficient of friction became larger. This is because the amount of the refrigerants dissolved in oil increased and the viscosity of oil dropped as the pressure increased.     

Numerical Analyses of Hydrodynamic Lubrication and Dynamics of the Rolling Piston and Crankshaft in a Rotary Compressor

In this article, numerical analyses of hydrodynamic lubrication and dynamics of the crank, rolling piston, and vane were carried out to study the tribological performance of a rotary compressor. Dimensionless Reynolds equations of journal and thrust bearings in dynamic load condition were derived and solved numerically. To deal with the lubrication of the rolling piston, the effect of the nonuniformity of tangential velocity over the bearing surface on the Reynolds equation was taken into account. In addition, combined with the analyses of dynamics and kinematics of the crank, piston, and vane, the angular velocities of the crank and piston as well as the motion mode between the piston and vane were studied. Analysis results illustrate characteristic oil film pressure distributions of the crank and piston bearings, which are different from that of common journal bearings. Under the influences of dynamic load and eccentricity of the cam, the wedge effect as well as the stretch and squeeze effect contribute greatly to hydrodynamic pressure. The relative motion mode between the piston and vane tip is not always pure sliding but accompanies rolling in some cases, which depends on the magnitude of the friction coefficient between the piston and vane tip. The analysis results are helpful for the improvement of rotary compressor design.     

低振动低摩擦铰接叶片式旋转压缩机的研究

介绍一种新型铰接叶片式旋转压缩机的结构和工作原理 ,对其运动机构进行了理论分析。研究表明 ,该压缩机比传统的滚动活塞式压缩机具有更低的振动噪声、更小的摩擦损耗以及更少的泄漏损失 ,是一种有实用前景的旋转式压缩机     

Estimation of leakage through radial clearance during compression process of a rolling piston rotary compressor

The leakage characteristics during the compression process in a rolling piston rotary compressor were investigated in this research. The thermodynamic conditions and geometric features during the compression process were determined from the results of a numerical compressor simulation. Refrigerant R410a and lubricant oil PVE-68 were used as working fluids. Leakage models with and without consideration of the lubricant oil effect were used to examine leakage characteristics through the radial clearance. A model for pure refrigerant that included the operating conditions and geometric characteristics of a compressor was developed using the verified results of a CFD (Computational fluid dynamics) simulation. The area ratios for both the refrigerant and lubricant oil at the radial clearance was obtained by numerical analysis during the compression process of the rolling piston rotary compressor. The results showed that the cross sectional area at the radial clearance would be charged with the pure refrigerant up to a maximum of 81.2 % during the compression process.

     

Numerical analysis of the piston secondary dynamics in reciprocating compressors

In this study, a numerical analysis for the piston secondary dynamics of small refrigeration reciprocating compressors is performed. In general, the length of cylinder in this class of compressors is shortened to diminish the frictional losses of the piston-cylinder system. So, the contacting length between piston and cylinder wall is in variable with the rotating crank angle around the BDC of the reciprocating piston. In the problem formulation of the piston dynamics, the variation in bearing length of the piston and all corresponding forces and moments are considered in order to determine the piston trajectory, velocity and acceleration at each step. A Newton-Raphson procedure was employed in solving the secondary dynamic equations of the piston. The developed computer program can be used to calculate the entire piston trajectory and the lubrication characteristics as functions of crank angle under compressor running conditions. The results explored the effects of some design parameters and operating conditions on the stability of the piston, the oil leakage, and friction losses.     

The friction characteristics of the journal bearing in a reciprocating compressor for refrigeration and air conditioning systems

The performance of a reciprocating compressor in refrigeration and air-conditioning systems is influenced by the lubrication characteristics of the critical sliding components. Thus, the lubrication characteristics between the crankshaft and journal bearing have to be researched in order to improve the design and performance of a reciprocating compressor. Therefore, in this study, to enhance the EER (energy efficiency ratio) to reduce power consumption, and to improve the reliability of a reciprocating compressor for refrigeration and air conditioning systems, theoretical analysis of the friction characteristics between the crankshaft and journal bearing in a reciprocating compressor is studied. The results demonstrate that frictional characteristics are significantly influenced by the clearance between the crankshaft and journal bearing and the viscosity of the lubricating oil.     

一种新型回转式制冷压缩机的结构设计

介绍了一种新型回转式制冷压缩机的工作原理及部件结构,它结合了当前部分回转式制冷压缩机的优点,克服了一些使用局限性。此种新型制冷压缩机零部件少、结构简单、制造方便、运行平稳、适用容量范围广。介绍了排气结构、能量调节机构、活塞柔性及密封机构。     

Synthetic and HVI compressor lubricants

This paper reviews the optimum synthetic and semi-synthetic lubricants for various types of compressors and gases being compressed. Several applications are given involving centrifugal, rotary, and reciprocating compressors. Gases include air, refrigerant, natural and other hydrocarbons, chemical processing and industrial. Included also are food grade air compressor applications. In addition, microlube systems for once-through cylinder lubrication of large reciprocating compressors designed to minimize gas contamination are also described.     

滚动转子式压缩机内转子径向间隙泄漏的研究

在滚动转子式压缩机内由于间隙配合造成的制冷剂泄漏中,转子径向间隙的泄漏量最大,它主要是以溶于润滑油的形式泄漏的。考虑到转子径向间隙的动态变化,利用润滑油流动模型来计算它的制冷剂泄漏量,并通过保持其他配合间隙不变只改变转子径向间隙的性能试验来验证泄漏对滚动转子式压缩机性能的影响。合理设计转子径向配合的间隙值,可以有效地降低滚动转子式压缩机的泄漏损失。     

双滑片椭圆转子压缩机径向间隙泄漏研究

建立了双滑片椭圆转子压缩机的径向间隙泄漏模型,对不同径向间隙的泄漏量进行了计算和分析,并和相同规格的滚动转子压缩机进行比较。结果表明:椭圆转子压缩机的径向间隙泄漏量在相同条件下大于滚动转子压缩机,两者的差值随着间隙的增大而增大,在间隙为80μm时,椭圆转子压缩机的径向间隙泄漏量最多可比滚动转子压缩机大2.352 g/s;压比对泄漏量的影响较大,在压比一定时,转速和转子椭圆面短轴和长轴之比对泄漏的影响并不明显。严格控制的径向间隙是提高椭圆转子压缩机容积效率的主要因素。     

采用油膜密封的转子压缩机内间隙泄漏研究

在转子压缩机内转子和气缸之间采用间隙配合，其泄漏通道通过油膜来密封的。考虑到转子径向间隙的动态变化，利用润滑油流动模型来计算它的制冷剂泄漏量，通过保持其它配合间隙不变，只改变转子径向间隙的性能试验来检验油膜的密封效果。结果表明，合理地设计转子径向配合的间隙值，可以有效地降低转子压缩机的泄漏损失。     

转缸驱动转子滑片压缩机运动分析

介绍了一种新型结构滑片压缩机的结构特点和工作原理，该新结构压缩机与传统滑片压缩机相比。改善了低速性能，具有更低的振动噪声和摩擦损失等优势。建立了机构模型，并分析了该压缩机的运动规律。     

滚动转子式压缩机泵体输入功率的计算

在确立的假设条件下,对叶片、滚套、曲轴等滚动转子式压缩机各关键运动部件进行了动力学分析,得出了压缩机泵体的输入功率表达式。为压缩机设计提供了理论基础。     

VRV空调系统压缩机-冷凝器联合调节特性与控制策略研究

通过对影响VRV空调系统压缩机-冷凝器模块换热量的压缩机频率、室外空气温度、冷凝温度、冷凝器风量的模拟分析，得出了不同参数对系统的影响和调节特性，提出了压缩机频率控制制冷剂流量，室外机风量控过冷度的新的控制原理和方法。     

制冷用新型双级压缩机设计及样机运行分析

提出了低温（-50℃）制冷专用双级压缩新方法,分析了以螺杆式压缩机做低压机,以活塞式压缩机做高压机的科学合理性。论证了新型机组与双级螺杆压缩机组、双级活塞压缩机组的性能比较与分析,浅析了复叠式制冷技术的特点与用途。样机运行结果显示各项技术指标达到甚至超过设计要求,是-45℃～-60℃制冷工况的最新技术。     

两级旋叶式膨胀机动力特性的理论研究

两级旋叶式膨胀机与传统旋叶式膨胀机在结构上有着明显的差别,能够实现更高的容积膨胀比,适合用于R410A等具有较高膨胀比的制冷系统。本文通过对两级旋叶式膨胀机运动和受力特征的分析,建立了滑片的受力模型,并应用该模型对拟开发的两级旋叶式膨胀机进行动力计算,分析比较了滑片的运动和所受各种力的计算结果,重点讨论了背压对滑片顶部与气缸壁面间接触力的影响,得出将滑片两侧工作腔中高压腔内工质引入背压腔的方法更适合于两级旋叶式膨胀机。     

THD Analysis of Rolling Piston and Journal Bearings in Rotary Compressors

A numerical analysis of the thermohydrodynamic lubrication of a rolling piston and two misaligned journal bearings in a rotary compressor has been carried out. The temperature rise of the oil film was calculated according to the transient energy equation of viscous fluid, and coupled analysis with the hydrodynamic lubrication of the rolling piston and journal bearings was conducted by using the finite element method and finite difference method. The distributions of the pressure and temperature rise of the oil film for several cycles were calculated. The analysis results show that for the journal bearings, the temperature of the oil film rises with the increase in pressure, the highest temperature appears around the region of the maximum pressure, whereas for the rolling piston bearing, there is a sharp peak in the temperature distribution. The maximum temperature in the oil film varies periodically with the rotation of the crankshaft, and after several cycles the balance between viscous heating and heat dissipation is achieved. The thermal analysis results were compared with those of the isothermal analysis. It is found that the difference in lubrication performance between the thermal and isothermal cases is relative small, due to the mild temperature rise in the bearing system.     

一种低摩擦低泄漏新型旋转式空调压缩机的设计与分析

针对目前滚动活塞式压缩机存在内部泄漏损失多和运动件摩擦损失大的缺陷,提出一种新型全封闭旋转式空调压缩机,该机采用新颖的减摩技术和密封结构,将叶片、端盖与旋转式的缸套紧固连接在一起并同步旋转,消除了这些部件之间的配合间隙,改善了它们之间的摩擦与泄漏状况。介绍了该类压缩机的工作原理和结构特点,探讨了将其作为房间空调器压缩机的设计思路。与传统滚动活塞式压缩机相比,新型旋转式压缩机在减摩、密封、消振、制造以及装配等方面确有其独特之处。