液黏调速器摩擦副油膜特性实验装置研究

为进一步研究液黏调速器摩擦副油膜流场的动力学特性,研制了一台用于模拟摩擦副油膜流场的实验装置,并设计了相应的实验数据采集系统和油膜厚度闭环控制系统。该装置采用液压系统、变频电机以及旋转液压缸机构,使得主动摩擦片转速和油膜厚度均可调,从而可以对不同转速和油膜厚度条件下的流场进行实验研究。采用该实验装置模拟了一定条件下的油膜流场,并采集了该流场中若干点的压力和温度数据。     

混合信号数据采集系统设计

文中描述了具有多路、多类型混合信号采集系统的设计。介绍了采用标记法保证采集的有效数字量与其他数据可靠分离,提供了采用线性光耦对模拟信号进行隔离的电路设计,多路数字量采集的总线复用电路设计和对脉冲量、阶跃量采集电路的设计,并给出了数字量采集的FPGA程序设计。     

基于MSP430F449的自动肺活量测试仪设计

介绍一种医用自动肺活量测试仪的设计方案,描述自动肺活量测试仪各部分电路的设计,给出系统AD转换的子程序。该系统以MSP430F449为控制芯片,采用MPXV7002压力传感器,简化电路设计;同时该设计方案体积小,耗电少,操作方便。     

基于动网格方法的油膜轴承性能的研究

考虑气穴的影响,建立了油膜轴承所支撑转子系统的动力学模型,并利用新的动网格更新方法,编制了求解油膜轴承压力分布、转子静平衡位置以及轴心轨迹的程序,验证了其正确性。利用该程序考察了气穴压力和转速对油膜轴承压力分布和所支撑转子的轴心静平衡位置的影响。计算结果表明,在相同的速度和载荷下,随着气化压力升高,轴承偏心率和最大油膜压力增大,偏位角减小,并且最大油膜压力的周向位置受气化压力的影响较小;而在相同的载荷下,转速对转子静平衡位置影响较大,并随着转速增加,轴承偏心率减小,偏位角增加。     

线阵CCD数据采集与USB2．0传输

介绍了线阵CCD数据采集电路设计和基于ISP1581的USB2.0接口电路设计,并设计了这两部分的DMA接口电路。讨论了USB2.0接口电路里的单片机固件程序,并完成了CCD数据读取和USB2.0传输的实验,传输速度达到近40Mb/s。     

宽厚板轧机油膜轴承润滑系统的优化应用

某钢厂轧机支撑辊采用油膜轴承结构,并用稀油润滑,针对原设计中存在的油压不稳、经常出现压力罐油液冲顶或排空从而造成系统进气或压力罐失去作用等问题,对4300mm宽厚板轧机油膜轴承润滑系统进行了改造。将手动阀门改为电控通断阀,由PLC系统自动检测压力罐的油位和气压,自动实现调整。经优化应用表明,系统运行稳定。     

基于Matlab的动压轴承油膜特性仿真研究

对动压轴承的静特性求解方法进行了理论研究,以Matlab为工具,通过联立Reynolds方程、能量方程、温粘关系及膜厚方程,利用差分法,编制计算程序,对油膜厚度场、温度场、压力场进行了数值求解,分析了油膜厚度、温度及压力分布规律。以某动压轴承为例,计算得出了该轴承下瓦的温度、压力及膜厚的数值,并获得了其三维模型,实现了油膜特性的可视化,使其具有较强的真实视觉感,有助于提高滑动轴承的设计质量,为轴承故障诊断提供了一种可行的途径。     

高频动载轴承内油膜压力特性

传统油膜压力特性研究大多忽略油膜的可压缩性以及轴颈惯性力对油膜压力的影响,但在高频动载荷或瞬态冲击载荷作用下,油膜压力随时间变化剧烈,而油膜密度、粘度等状态参数又是关于压力的函数,油膜不可压缩性假设不再适用.另外,轴颈本身具有很高的加速度,因轴颈高速运动而产生的惯性力也不能被忽略.因此,同时将可压缩性以及轴颈惯性力引入到油膜压力的数值计算,可使计算结果更符合实际物理现象.建立考虑轴颈惯性力的力平衡方程以及考虑油膜可压缩性的雷诺方程,计算轴承在瞬态冲击载荷如矩形脉冲、三角形脉冲以及正弦周期性载荷作用下的油膜压力特性,分析数值计算结果,研究外载荷幅值、脉宽以及相对间隙对油膜压力特性的影响,研究发现,相对间隙越大,轴颈惯性作用越不能被忽略;油膜压力衰减速度并不随外载荷幅值单调变化,外载荷幅值极小或外载荷幅值极大,量纲一油膜压力衰减速度均较快;脉宽变化对量纲一油膜压力衰减速度影响不大.在考虑可压缩性以及轴颈惯性力情况下,油膜压力时历曲线上会出现拍振现象.     

考虑黏-温及空穴效应的低速滑动轴承润滑性能分析

在低速重载条件下,温度升高导致的润滑油黏度下降以及局部压力过低产生的油膜空穴,严重影响到油膜压力与承载力等润滑性能。为探究考虑黏-温及空穴效应的低速滑动轴承润滑性能,通过编写黏-温方程的UDF程序,建立滑动轴承的Fluent有限元模型,考虑Mixture多相流模型的空穴效应,系统计算轴承油膜在不同工况下的润滑性能,分析对比偏心率、轴系转速以及黏-温效应的影响作用。结果表明：考虑黏-温效应条件下的油膜最大压力、最大温度、承载力以及空穴区域气穴最大体积分数均小于黏度恒定的情况,轴系转速和偏心率的增大会导致空穴区域最大体积分数的增加。     

高速线接触热弹流分析

应用多重网格法和多重网格积分法,开发了线接触弹性流体动力润滑C 计算程序.针对航空领域中无量纲速度为10-9的高速线接触弹流情况,应用该程序求得了高速情况下Newton流体和Ree-Eyring流体的弹流数值等温解及热解,分析了热效应和非牛顿性对润滑的影响,验证了计算程序的可靠性.在相同无量纲速度下,研究了滚滑比和滑油粘度对润滑性能的影响.结果表明:随着滚滑比的增加压力峰逐渐变小,油膜厚度变薄,油膜温度显著增加;高速情况下,粘度大的润滑油可以增加油膜厚度,但是压力峰增大,油膜温度也升高很多.     

波箔动压空气径向轴承实验台设计

现有的波箔动压空气径向轴承实验台存在最大工作转速达不到轴承实际工作转速,无法在不影响轴承正常工作的情况下对轴承施加径向载荷,无法测量轴承的阻力距等缺点.为了全面满足波箔动压空气径向轴承的实验需要,设计一种最高转速为60 000 r/min的波箔动压空气径向轴承实验台,可以在不影响轴承正常工作的情况下对轴承施加径向载荷,可以同时测量转轴转速、轴承阻力距、转轴水平和竖直方向的位移、轴承工作温度、冷却空气的压力.     

A new approach to measure the friction coefficient of micro journal bearings

A new approach and relevant test rig to measure the friction of micro journal bearings are introduced in this paper. The micro bearings under the load of milliNewton scale can be tested to indicate their tribological behavior. The test rig has the following features. (1) The separated bearing halves are attached to the journal with a soft string wrapped around them. The string is strained in a vertical line with the upper end located at a beam and the lower end hanged with a standard weight, which supplies pressure between the bearing and the journal, without bending the spindling journal. (2) The frictional force of the rotating journal on the bearing halves will result in a difference between the forces at the two string ends. (3) This force difference can be sensitively detected by strain gauges on the beam. Therefore, the micro friction between the bearing and the spinning journal can be detected and indicated.     

超临界二氧化碳动静压径向可倾瓦轴承实验台设计与实验研究

针对超临界二氧化碳(S-CO₂)动力机组在启动和停止阶段气体轴承产生非常大的摩擦磨损,以及气体轴承承载力低、刚度低、阻尼小、稳定性较差等问题,设计并改进一种新型动静压S-CO₂润滑径向可倾瓦轴承结构。设计并搭建S-CO₂润滑轴承实验台,针对于实验台转子刚启动和极低转速工况,对新型S-CO₂润滑动静压径向轴承在静压状态下的动态特性进行实验研究,得到轴承的动态刚度和动态阻尼,并分析静压对轴承动态性能的影响。实验结果表明,设计的S-CO₂动静压径向可倾瓦轴承在启停阶段,在轴瓦与轴颈之间产生了足够的静压压力,可将二者完全分隔开,从而能减少启停阶段的摩擦磨损;随着静压压力的增大,轴承X、Y方向上的整体刚度、主阻尼都增大,且2个方向的主刚度系数差别不大,而交叉刚度和交叉阻尼都接近于0。研究结果为进一步揭示S-CO₂润滑径向轴承动压状态特性提供参考。     

Temperature,pressure and film thickness measurements for an offset half bearing

A fluid film journal bearing test rig with a shaft, 70 mm in diameter, was developed and an offset half journal bearing was tested at five vertical loads and two rotational speeds. The bearing had a length-to-diameter ratio of 1.00, a pre-load factor of 0.51 and an offset factor of 1.0. Loads from 0 to 4450 N and speeds of 2250 and 1650 rev min⁻¹ were tested. On-rotor instrumentation and amplification are used to measure continuous fluid film pressures around the bearing, film thicknesses and journal temperatures. Slip ring telemetry is used to transmit the data to a real time data collection system. External instrumentation is used to measure film pressures and temperatures in discrete locations on the bearing surface, thus, allowing comparison with the on-shaft measurements. The eccentricity ratio and attitude angle are pressure measurements obtained indicate agreement within 5% between the results recorded by the on-shaft and the external pressure transducers. The experimental film thickness, temperature and pressure profiles and journal eccentricity agree with the expected behavior for this bearing type and are presented for Sommerfeld numbers from 0.41 to 2.2.     

氨压缩机径向可倾瓦轴承性能的试验研究

在倒置式轴承试验台上，对某氨压缩机组径向可倾瓦轴承进行了试验研究，成功地测出了轴承的功耗、流量及最小膜厚等参数。结果表明，在给定工况下、控制进油温度、压力与轴承间隙，可显著改善试验轴承的性能，为该轴承的改良提供了依据。     

Investigation of the tribological properties of silicon containing zinc–aluminum based journal bearings

In this study, frictional behavior of thin-walled journal bearings produced from Zn–Al–Cu–Si alloys was investigated using a purpose-built journal bearing test rig. The alloys were produced by permanent mould casting. Mechanical properties such as ultimate tensile strength, elongation, hardness and microstructure of these alloys were determined. The friction properties of the bearings produced from these alloys were also investigated. In this investigation, the effects of surface roughness and bearing pressure on the frictional properties of the journal bearings were taken into account. The results showed that friction factor decreased with increasing bearing pressure especially in the mixed and full-film lubrication zones. It was found that high surface roughness led to high friction factor. The ZnAl27Cu2Si1 and ZnAl40Cu2Si1 bearings showed full Stribeck curve tendency while ZnAl27Cu2Si2 bearing did not exhibit the typical diagram having no full-film lubrication zone at the pressure of 0.7 and 1.1 MPa.     

Measurement of friction force and effects of oil fortifier in engine journal bearings under dynamic loading conditions

Commercial base oil and oil fortifier added to this oil are used to investigate the frictional behavior of the engine journal bearings using the theoretical Reynolds equation and experimental test rig. In the theoretical part of the study, the Reynolds equation that states the pressure distribution and friction force with finite width was solved by using the finite difference method. In the experimental part of the study, a new design test rig was conducted to measure the friction force, the lubricant film thickness of the engine journal bearing using base oil under dynamical loaded conditions. The effect of oil fortifier was detected measuring the friction force every three minutes in each 360 crank angle during 15 minutes of experiment. As the theoretical friction results showed similar variation with the experimental measurements of engine bearings, adding oil fortifier to the base oil presented a substantial reduction of friction force during the testing period.     

An experimental investigation on frictional behavior of statically loaded micro-grooved journal bearing

Performances of plain and micro-grooved engine journal bearings were investigated in this study. Numerous experiments were performed under different static loads by using the purpose-built journal bearing test rig. Micro-grooves were made by cutting micro-channels both around and across the engine journal bearing surfaces. Stribeck curves for the micro-grooved and the plain journal bearings were then experimentally and theoretically generated while frictional torque versus angular velocity curves were also plotted. The results showed that the highest value of coefficient of friction as well as the frictional torque was obtained on the transversal micro-grooved journal bearings.     

Experimental investigation of the temperature fade in the cavitation zone of full journal bearings

This paper describes an experimental investigation with a rig for measuring the surface temperatures and pressures in single bore journal bearings. The test bearing was equipped with small bores, where the pressure was altered by means of a vacuum pump. The whole bearing arrangement can also be operated at different ambient pressures ranging from atmospheric down to −0.06 MPa. Oil temperatures at inlet and outlet are also measured. Experiments show a considerable drop in the temperature of oil undergoing a drop in pressure. The overall temperature level of the bearing system did not seem to affect the magnitude of the temperature drop. Experiments where the bearing system was operated at sub-ambient pressures revealed an increased temperature drop in the cavitation zone. Pressures higher than ambient were measured within the cavitation zone while the bearing was operated at sub-atmospheric pressure. The higher pressures are believed to be caused by evaporation of oil. It is therefore proposed that the temperature drop observed in the cavitation zone of journal bearings is primarily caused by evaporation of oil. However, isentropic decompression of the gases in the oil is also believed to play a role.     

An experimental investigation on frictional behavior of statically loaded micro-grooved journal bearing

Performances of plain and micro-grooved engine journal bearings were investigated in this study. Numerous experiments were performed under different static loads by using the purpose-built journal bearing test rig. Micro-grooves were made by cutting micro-channels both around and across the engine journal bearing surfaces. Stribeck curves for the micro-grooved and the plain journal bearings were then experimentally and theoretically generated while frictional torque versus angular velocity curves were also plotted. The results showed that the highest value of coefficient of friction as well as the frictional torque was obtained on the transversal micro-grooved journal bearings.