Study of traction efficiency on traction type continuously variahle transmission

以牵引式无级变速器为研究对象,推导出了自转角速度、由油膜滑动产生的牵引力和由自转产生的力矩等解析式.通过实例,计算和分析了牵引效率与接触压力、油膜牵引力、输入转速和几何曲率比等因素间的变化规律.     

平行板挤压油膜噪声试验设计

汽车发动机主轴由油膜支承其旋转,随着技术的进步,由发动机活塞与齿轮啮合等引起的噪声水平逐步下降,从而使主轴承油膜产生的类似机械打字声的无规律发动机噪声浮现出来,并引起一些汽车公司的关注。已有该不寻常发动机噪声现象研究工作均认为油膜空穴破裂是产生此噪声的根源,为简化问题,突出主要现象,特在挤压油膜研究的基础上,改进现有平行板挤压油膜力试验机,增加油膜噪声等参数测量;初步试验获得了无规律噪声现象,通过对比分析采集的声音、位移、振动和油膜挤压力四种信号之间的关系,发现四种信号的峰值在同一时刻产生,并用高速CCD拍摄到出现无规律噪声时的清晰空穴图像。     

汽轮机油膜振荡影响因素分析及措施研究

所谓油膜振荡是指旋转轴受到滑动轴承中的油膜作用,所产生旋转轴的自激振荡,能够产生和旋转轴在达到临界的转速时相同的振幅,或者使之变得更加激烈。油膜振荡是中小型汽轮机组在运行过程中常遇见的机械故障之一,中小型汽轮机组,安全的运行受到油膜振荡的影响。影响中小型汽轮机组产生油膜振荡的因素有很多,主要有轴系结构的设计、轴承负载、润滑油粘度以及轴瓦间隙等,针对产生油膜振荡的这些因素要制定相应的措施,防止油膜振荡的产生,使中小型汽轮机组安全的运行。     

现代大型轧机油膜轴承DF密封技术

油膜轴承又称全液体摩擦滑动轴承,由轴颈、轴瓦、密封件、缓冲器等主要部件组成。工作过程中,轴颈和轴瓦之间的油被无限挤压,产生楔形效应,从而形成油膜。油膜将轴颈和轴瓦两个具有高速相对运动的部位分隔开来,形成了液体内摩擦,并具有强大的承载能力,使油膜轴承能够适应现代轧机高速、重载的工况条件,而且具有许多其它类型轴承无法比拟的显著优点,因而在现代大型轧机上得到越来越广泛的应用。     

液压轴承油膜稳定性分析

为了防止液压轴承在高速运行中,动态油膜产生自激振动,论文对油膜失稳机理作了分析和研究,结合工作需要,对防止油膜涡动的检验方法等进行了论述和实际计算,对设计和参数优化提供了有用的参考和指导作用。     

滑动轴承油膜振荡故障诊断及在线消除

阐述滑动轴承油膜涡动和油膜振荡的机制,通过实验运用振动分析软件给出不同间隙时轴承油膜涡动和油膜振荡的特征,找出影响轴承产生油膜涡动和油膜振荡因素,提出了防止油膜涡动及油膜振荡的措施,给出一种油膜涡动和油膜振荡在线消除方法.分析表明,防止油膜涡动及油膜振荡的措施有:提高轴的临界转速,减小轴承长度,增大轴承偏心率以及调节润滑油的供给量等.其中调节润滑油的供给量是一种可尝试的实现油膜振荡在线消除有效方法.     

柴油机滑动轴承的故障的声发射诊断

轴承是影响内燃机安全运行的重要零件,内燃机的主要运动件中,大多采用滑动轴承。滑动轴承采用流体动力润滑,曲轴的旋转作用形成油楔承载,同时零件表面对油膜挤压产生承载力。内燃机的轴承承载油膜压力由旋转油膜压力和挤压油膜压力构成。主轴瓦和连杆轴瓦在交变载荷下工作,轴承载荷的方向、大小都是周期变化的,所以轴承内不能保持均匀、恒定的承载油膜。在高速、高负荷,特别是在润滑状态不良或进入磨料时,轴承中产生较大的摩擦损失,摩擦损失转变成热量使轴承温度升高,降低润滑油粘度,使承载能力下降,再加上轴承座及轴的变形,润滑油流量不足及变质等,使轴承工作条件恶化,造成轴承损坏,如磨     

基于周期性挤压条件下弹流油膜的研究

球体周期性冲击弹流问题已得到解决,以前的实验研究也已被数学模拟论证。在载荷持续期间,中心油膜厚度和频率在对数坐标下呈线性关系,数值模拟结果表明,中心油膜厚度随时间逐渐减小和试验结果相似,数值模拟结果是一个涡状油膜形状,它是由接触区域较高的压力产生,频率和静载对油膜厚度和压力的影响也得到了论证。     

超声切削加工中的动压油膜模型建立及其试验研究

根据超声切削过程的运动特性和冷却液作用特征,基于流体动压理论,建立刀具与工件之间动压油膜的模型。分析前刀面油膜压力的变化规律、分布状态和试验的工艺效果,证明超声切削过程可以产生高冲击动压的油膜,油膜压力的作用可使切屑产生弹性变形甚至是挤压变形和剪切滑移。超声振动切削过程会形成油膜作用和刀具接触切削两个阶段,油膜的作用可以增大剪切角,使刀具锐化并改变刀具前刀面与切屑的接触状态,提高加工的表面质量。讨论了油膜状态和切削液粘度对加工效果的影响。     

石油化工滑动轴承油膜振荡的故障诊断综述

介绍了石油化工行业中滑动轴承油膜振动的产生原因;经对Reynolds方程求解,比较了三种动态油膜力解析模型,得到反映油膜运动规律的函数关系式及油膜力分布;再从油膜振荡特征着手对油膜振荡作了比较系统论述,并在前人的基础上总结了油膜振动的预防和处理措施。     

Experimental and computational investigation of the traction coefficient of a ball traction drive device

Traction drive is a new kind of drive manner in which the power is transmitted by a thin oil film between transmission elements. This paper describes a ball traction drive device. The quasi-dynamics analysis was carried out for the transmission components of the ball traction drive device. The traction coefficients of oils Ub2 and HH-20 were calculated respectively with different rheological models. The elastohydrodynamic lubrication (EHL) film thickness and the traction coefficient between traction drive elements were measured. The results of the calculations are consistent with experiments.     

Experimental measuring set‐up and procedure for the traction coefficient on roller‐on‐disc contact

A pin‐on‐disc machine was modified to measure traction coefficient and the potential of contact difference under controlled conditions of slide‐to‐roll ratio, temperature, contact pressure and entrainment speed; oil, grease, grease's base oil and bleed‐oil were tested. This new arrangement proved to be efficient to characterise lubricants traction behaviour, film separation and tribofilm generation. Copyright © 2016 John Wiley & Sons, Ltd.     

用T-J模型分析新型高速航空润滑油的拖动特性

在自行研制的高速润滑油拖动特性试验台上对新型高速航空润滑油进行拖动特性的试验；根据试验数据推导出润滑油的流变参数；基于T-J弹塑模型，求出拖动力的大小。结果表明：T-J模型具有一定的局限性，适用的试验每件比较窄。     

Simulating angular ball bearing lubricated elliptical contacts Film thickness and traction measurements

A high performance barrel and plate apparatus was built to study film formation and traction by simulating the real situation of a lubricated elliptical contact in an angular ball bearing under general kinematic conditions. Simultaneous measurements of load, speed of each surface, traction, and film thickness by optical interferometry can be performed. The sapphire disc plate and the steel barrel are driven independently at constant controlled speeds. Small relative sliding, lateral sliding and spinning near pure rolling conditions can be imposed by controlling barrel shaft angle contact location. Tests were performed at ambient temperature for a small barrel whose principal radii are 1.34 mm and 9.7 mm, for applied loads which generate Hertzian pressures up to 2 × 10⁹ N/m², and for a low viscosity mineral oil. Typical experimental results show that under elasto-hydrodynamic conditions, the centre film thickness is slightly below the values calculated from classical elastohydrodynamic theories and that oil starvation occurs at high speeds. Traction curves versus slide/roll ratio are presented for different loads and under spinning and lateral sliding conditions.     

Experimental Investigation of Lubrication Film Starvation of Polyalphaolefin Oil at High Speeds

The lubrication behavior of starved elastohydrodynamic contacts at high speeds was investigated in this study. A new ball-on-disc test rig with the ability to measure traction force at high speeds up to 100 m/s and lubrication film thickness at speeds up to 42 m/s was built. The relative optical interference intensity technique was used to measure the film thickness. The experimental results show that the film thickness decreased rapidly and asymmetrically when the speed exceeded a critical speed under the starved lubrication condition. Starvation is governed by the amount of lubricant available both in the inlet region and on the side of the oil reservoir. The shape of the oil reservoir becomes asymmetric and the amount of oil gradually reduces against the speed at high speeds because of the centrifugal effects, under which the oil on the outer side of the oil reservoir will be thrown away and the oil on the inner side of the oil reservoir will be compressed. The balance of oil supply and oil loss due to centrifugal force determines the starvation behavior.     

航空润滑油拖动特性动态数据库的建立

建立的润滑油拖动特性动态数据库具有查询、计算、绘图、比较、维护和设置步长等多项功能.通过该数据库,可以查到多种航空润滑油在多种工况条件下的拖动系数及拖动系数计算公式中的系数值,可以对不同润滑油的拖动系数进行比较及同一种油的计算值和试验值进行比较.     

Molecular interaction originating from polar functional group in lubricants and its relationship with their traction property under elastohydrodynamic lubrication

The correlation between molecular interaction and traction properties was investigated using a traction tester and in situ observation of elastohydrodynamic lubrication film with a micro‐Fourier transform infrared spectrometer. The sample oils used were polypropylene glycols (PPGs) with the end‐group of alcohol or ether and a synthetic hydrocarbon oil, poly‐α‐olefin. From the traction tests, it was found that the traction coefficient of PPG was sensitive to the end‐group. PPG with alcohol as the end‐group showed a higher traction coefficient than that with the ether group. In situ observation with a micro‐Fourier transform infrared was performed in order to investigate the molecular interaction of the lubricant oil. It was found that the hydrogen bonding of hydroxyl groups in PPG was strengthened by high pressure in the Hertzian contact region. These results suggest that the rheological properties in the elastohydrodynamic lubrication contact region were affected by the strengthened hydrogen bonding. Copyright © 2014 John Wiley & Sons, Ltd.     

汽车/护栏碰撞试验室牵引动力系统的设计

通过对汽车/护栏碰撞试验室的牵引系统结构进行分析,提出了电力牵引动力系统的设计思路和方法。以18 t的碰撞车辆在80 km/h的速度为前提条件,建立了碰撞车辆的动力学模型和电动机的牵引模型,并基于牵引系统的结构和模型对牵引系统的各参数进行了可行性优化设计。将理论分析计算结果和汽车/护栏碰撞试验室的实际建设情况进行了对比分析。结果表明,该牵引动力系统设计合理,说明了这种设计方法在设计碰撞牵引动力系统时的可行性及有效性。     

A non-averaging method of determining the rheological properties of traction fluids

Traction machines have been frequently used to study the rheological responses of lubricants in elastohydrodynamic lubrication (EHL) contacts. Fundamental properties are inferred from EHL traction measurements based on the average pressures and temperatures in the contact. This average approach leads to uncertainty in the accuracy of the results due to the highly nonlinear resonse of the fluid such as viscosity to both pressure and temperature. A non-averaging method is developed in this paper to study the elastic and plastic properties of traction fluids operating in EHL contacts at small slide-to-roll ratios. A precision line-contact traction rig is used to measure the EHL traction at a given oil temperature and Hertz pressure. By choosing a sensible pressure-property expression, the parameters of the expression can be determined through the initial slope and peak traction coefficient of the traction measurements. The elastic shear modulus and the limiting shear stress of the lubricant corresponding to a single pressure can then be calculated for a range of pressures and temperatures of practical interest. Two high-traction fluids are studied, and their elastic moduli and limiting shear stresses presented.     

Friction and film‐forming behaviour of five traction fluids

There is growing interest in the use of toroidal‐type traction drives to provide continuously variable transmissions for use in medium‐ to high‐power automotive engines. These transmissions require the use of specially designed traction fluids to provide high friction in full‐film elastohydrodynamic lubricated contacts. This study has measured the film‐forming and traction properties of five commercially available and developmental traction fluids to provide data needed to predict their performance in traction drives. Some differences in performance between the fluids have been noted.