阶跃载荷扰动下径向滑动轴承绝热瞬态过程研究

研究了径向滑动轴承在阶跃载荷扰动下的绝热瞬态行为.通过对轴承油膜压力、温度及轴颈的动力学建模,应用数值方法对模型求解.获得了大载荷扰动工况下径向滑动轴承热瞬态运动参数的非线性响应.给出了瞬态过程中轴承最高温度、最小膜厚等其他参数的变化规律.结论认为,瞬态过程中温升、膜厚参数变化很大,并且超出了其要达到的稳态值,有可能造成瞬态过程中轴承由于温升过高而失效.     

柴油机滑动轴承热流体动力润滑仿真研究

根据径向滑动轴承热流体动力润滑理论,基于JFO理论提出的质量守恒边界条件,建立同时包含油膜完整区和空 穴压力变化的单缸柴油机滑动轴承热流体动力润滑模型,采用有限差分法求解模型方程,仿真分析滑动轴承的油膜厚度、油膜压力、润滑油流量和温度等参数对润滑性能的影响,分析内燃机滑动轴承润滑特性,为轴承润滑可靠性设计提供一定的理论依据.     

载荷扰动下滑动推力轴承绝热瞬态过程分析

分析了滑动推力轴承在载荷冲击下的绝热瞬态行为.通过对轴承油膜压力、温度及推力盘动力学建模,应用有限差分法以及Newton-Raphson法对模型求解,获得了大载荷扰动工况下滑动推力轴承热瞬态性能参数的非线性变化规律.讨论了载荷幅值,初始速度等对热瞬态过程的影响.结果表明,载荷冲击会在短时间内造成油膜温度显著升高及最小膜厚减小,从而导致轴承在瞬态过程中失效.     

滑动轴承动力特性系数动态分析方法

采用滑动轴承动力特性系数动态分析方法用以研究滑动轴承动力特性系数瞬态响应.分别采用有限元法与有限差分法分析转子瞬态响应与油膜流场压力分布;数值积分油膜压力关于扰动的偏微分项求解滑动轴承动力特性系数;在每个时刻采用学科间迭代方法实现转子响应分析与滑动轴承动力特性系数分析之间的耦合.以某型涡轮增压器转子系统为例,分别采用动态滑动轴承动力特性系数与定滑动轴承动力特性系数分析转子系统瞬态响应;讨论间隙宽度、轴承长度和润滑油粘度对动态滑动轴承动力特性系数的影响,并与文献中的结论进行比对,验证该方法的有效性.     

多瓦可倾瓦径向滑动轴承热弹流润滑分析

考虑轴瓦弹性变形,建立多瓦可倾瓦径向滑动轴承热弹流润滑(TEHD)分析的数学模型,对比分析多瓦可倾瓦径向滑动轴承热流体动力润滑(THD)与TEHD模型的润滑性能差异,分析轴瓦弹性变形对轴承润滑性能的影响.结果表明,轴瓦弹性变形导致最小油膜厚度减小、流体动压力的梯度下降,但对瓦面温度的影响较小;THD模型高估了轴承的承载能力,在高速重载的场合,这种误差可能导致轴承润滑失效.因此,在滑动轴承设计中有必要考虑轴瓦弹性变形对轴承润滑性能的影响.     

考虑轴颈偏斜的多瓦径向滑动轴承热流体动力润滑分析

建立考虑轴颈偏斜的多瓦可倾瓦径向滑动轴承热弹流润滑(TEHD)分析的数学模型,求解轴瓦表面当量弹性变形,计算得到轴颈偏斜时的瓦块油膜厚度、油膜压力分布和瓦面温度分布等,并对比分析无轴线偏斜和有轴线偏斜情况,得到多瓦可倾瓦径向滑动轴承的热弹流润滑性能差异.结果表明,TEHD模型下,轴颈偏斜会导致轴承油膜厚度、油膜压力和瓦面温度等分布在轴向不对称,并且导致轴承油膜厚度明显减小.     

阶跃载荷扰动条件下推力轴承热瞬态过程研究

用一维绝热模型研究了滑动推力轴承在阶跃载荷冲击下的热瞬态行为.通过对轴承油膜压力、温度和推力盘的动力学参数进行建模,应用有限差分以及Runge-Kutta法等对模型求解,获得了大载荷阶跃冲击条件下推力轴承热瞬态过程中性能参数的非线性响应曲线,给出了瞬态过程中轴承最高温度、最小膜厚等参数的变化规律.结论认为如果轴承设计和运行不当,轴承有可能因为瞬态过程中温升过高或膜厚的突然减小而失效.     

EMP径向滑动轴承热弹变形对润滑特性的影响

ＥＭＰ径向滑动轴承特殊的轴瓦材料特性使得其热弹变形对轴承的润滑特性,如油膜的最小间隙、油膜压力和温度分布影响较大。为此本文建立了完整的热弹变形模型,采用有限差分的方法,通过在不同载荷的情况下,对ＥＭＰ径向滑动轴承在计入和未计入热弹复合变形的两种情形进行对比,从而揭示了热弹变形影响轴承工作性能参数的内在规律。     

水介质液压泵锥形轴配流副轴承间隙的计算

以水介质轴向柱塞液压泵的锥形轴配流副为研究对象,对其在稳定工作状态下形成的滑动轴承的径向间隙计算方法进行了研究。采用等效结构参数法将配流副滑动轴承化为轴向推力轴承,根据柱塞轴向液压交变作用力引起轴承内水膜的变化特征推导出水膜厚度变化的速度,再依据锥顶体薄膜挤压效应公式计算出了轴承的径向间隙,结果表明径向间隙是柱塞泵工作压力和配流副结构参数的函数。     

弹性金属塑料瓦径向滑动轴承启动过程热弹流分析

研究了采用弹性金属塑料轴瓦时径向滑动轴承的瞬态润滑特性。建立了该轴承的三维热弹流模型，通过数值求解对比了启动过程中采用弹性金属塑料轴瓦和金属材料轴瓦时油膜和轴瓦的瞬态温度场分布、轴瓦的热弹变形量，以及转子轴心轨迹。结果表明，在启动初期弹性金属塑料瓦径向滑动轴承的瓦体温度要高于金属瓦，转子偏心率也要大于采用金属瓦时的偏心率；因润滑油在弹性金属塑料瓦径向滑动轴承轴瓦表面存在一定的滑移速度，随着油膜边界滑移作用的出现，采用弹性金属塑料瓦径向滑动轴承时的油膜温度最终低于采用金属瓦时的温度，且转子的偏心率也最终小于采用余属瓦的偏心率。     

Thermal Resistance of a Tapered Roller Bearing

An apparatus to simulate the thermal behavior of a tapered roller bearing was constructed and used to determine tapered roller bearing thermal behavior. Bearing specimens can be loaded axially and/or radially while rotating. Shaft heating is also provided and mechanical losses measured. An infrared scanner and thermocouples allow for temperature measurement. An analytical model of the bearing and bearing/housing system was also developed and is presented. The model is capable of considering various modes of bearing operation. Experimental and theoretical resistances are compared. Typical thermal resistances from shaft to housing were found to be of the order of 1 K/W.     

Effect of thermal deformation on machine tool slide guide motion

This paper describes the effects on machine slide-guide contact conditions caused by thermal deformation. Since a slide guide has a large friction surface, the motion is greatly influenced by thermal distortion caused by heat generation in the ball nut and the bearing support, during machining processes. This study investigated the typical behavior of the friction coefficient in response to both the external load and the linear speed. This then led to investigating the thermal effects on the slide motion. The thermal deformation of the slide table was measured with respect to the running time and the linear motion and the frictional power were monitored and compared directly with the thermal distortion.     

Study on thermal induced preload of ball bearing with temperature compensation based on state observer approach

The internal contact feature and thermal induced dynamic preload is essential for ball bearing, which is one of the key issues for thermal instability and stuck problems at high rotation speed. This paper presented a thermo-mechanical coupling model for angular contact ball bearing with preload and temperature compensation, for the purpose of dynamic preload monitoring. Based on the verified thermal balance equations, thermal deformation and thermal induced preload were achieved and feedback to the original local approach of heat generation calculation. Then, the nonlinearity and uncertainty heat transfer characteristic was considered via a state observer to verify the calculation process. The state variable of bearing’s temperature rise was defined and a state observer with proportional-integral term was designed. The difference between experimental data and calculation result was feedback by the observer to control the heat transfer and preload solving process. Thus, the real-time temperature rise, thermal deformation, and dynamic preload of bearing’s internal assemblies were obtained.     

Effect of Bearing Surroundings on the High-Speed Spindle-Bearing Compliance

This paper investigates the effect of bearing assembly tolerance on spindle-bearing compliance. In a high-speed spindle system, the bearing characteristics are influenced significantly by the initial assembly tolerances and the thermal deformation of the bearing surroundings. In the very early stage of spindle operation, spindle bearings could be under hazardous conditions owing to the rapid change of the internal pressure resulting from thermal deformation or centrifugal force-oriented deformation. The bearing’s internal clearance also may be changed by the operating conditions such as external load, rotational speed, and operating cycle time. To determine the initial tolerance and the optimal cooling regimen, a comprehensive dynamic modelling and analysis of a high-speed spindle system in terms of bearing pressure, bearing compliance, and heat generation is required with consideration of those effects. Moreover, in order to predict spindle characteristics in operation, all of these parameters should be monitored and recalculated in real-time. For this purpose, very simple and effective equations are suggested, representing the bearing stiffness in accordance with the thermal deformation. Most former bearing analyses were based on the Hertzian contact model, without considering the radial elastic defor-mation of the races. In this paper, analytical and experimental investigations of the bearing compliance are conducted with consideration of both the elastic deformation of the race and the thermal deformation of the housing in terms of the bearing stiffness. The experimental results show the effectiveness of the proposed equations, which are simple and useful for fast calculation of the bearing stiffness by dynamic simulation.     

航空发动机轴承腔热状态参数的分析模型

本文分析了影响轴承腔热状态的主要热源,建立了轴承及石墨密封摩擦热的计算模型、密封热泄漏量的计算模型、对流换热系数的计算模型及轴承腔温度场计算模型。这些模型的建立为轴承腔温度场和发动机最佳滑油量的计算奠定了基础。     

内燃机滑动轴承性能正交试验方法研究

针对内燃机滑动轴承性能影响因素的复杂性，结合CAE技术和正交试验设计法来分析内燃机滑动轴承润滑性能，确定了关键影响因素分别是转速、间隙、宽度、润滑油粘度，得到了适合该轴承润滑性能关键因素的最佳组合。仿真计算结果表明，该组合是最优的。最后检验了正交试验法在分析内燃机滑动轴承润滑性能方面的正确性。     

Steady state characteristics of a tilting pad journal bearing with controllable lubrication: Comparison between theoretical and experimental results

This paper is aimed at presenting results regarding the static and thermal behavior of a tilting-pad journal bearing operating under controllable regime. The bearing is rendered controllable by injecting high pressure oil into the clearance using holes drilled across the bearing pads in the radial direction. The modification of the injection pressure enables to modify the bearing static and dynamic properties according to the operational needs. The results presented are obtained using a theoretical model, which considers all the effects that determine the bearing behavior (controllable elastothermohydrodynamic lubrication regime), as well as using a test rig designed and built to this effect. The comparison between experimental and theoretical results provides solid ground to determine the accuracy of the available model for the the prediction of the steady-state behavior of the tilting-pad bearing with controllable lubrication. Among the parameters considered for the study are: oil film temperature field, resulting forces over rotor and pads, and rotor equilibrium position. The results obtained show good agreement between theory and experiment, as long as the assumptions on which the model is based are respected. Also, it is shown that some improvements are possible when it comes to model the steady-state behavior of the controllable bearing with the injection system turned off.     

计入套圈变形和润滑影响的球轴承动刚度研究

针对传统拟静力学分析方法未考虑轴承套圈热变形、离心力变形和弹流润滑作用引起轴承内部沟道曲率中心与滚动体中心几何位置关系的变化,难以准确反映轴承动刚度不足的现状,建立了计入套圈变形和弹流润滑影响的轴承拟静力学修正模型。采用所建立的模型研究了轴承不同工作转速和预紧力条件下轴承热变形、离心力变形和润滑油膜对动刚度的影响规律,通过与Gupta等典型算例及实验的对比验证,证实了所建立模型及分析结果的有效性。