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Magnetic fluid rotary vacuum seals have been shown to be effective in machinery operating in a vacuum chamber. Such seals have the advantages of simple design, zero leakage at almost any rotation speed, and low friction. They have no wear and require no maintenance. This paper presents results obtained from experimental investigations of the operation of magnetic fluid rotary seals under vacuum conditions. The paper discusses the test apparatus and the seals used, the test conditions, and the procedure. The experimental results show characteristic phenomena observed in magnetic fluid rotary vacuum seals, including changes in vacuum pressure, temperature, and frictional moment dependent on the rotation speed of the shaft, number of sealing stages, height of the sealing gap, and mean magnetic flux density in the sealing gap. 相似文献
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The magnetic fluid, having an ultra-low vapor pressure property of 7·0×10−10 Pa at 293 K, was prepared. Hexafluoropropylene oxide polymer oil having high molecular weight was used as base oil. Magnetic particles were dispersed by using two types of new designed and synthesized hexafluoropropylene oxide acid derivative surfactants. The obtained magnetic fluid had a saturation magnetization of 35·0 mT, its magnetite particles were dispersed stably and showed a superior resistance to active gasses. It was ascertained that the magnetic fluid vacuum seal using the prepared fluid had the ultra high vacuum performance. 相似文献
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行波磁场的产生、泵体结构的设计、磁性流体的动力学特性是磁性流体行波泵研究的关键技术。本文根据行波磁场产生的形式设计了直线型磁性流体行波泵,采用解耦计算分析和求解了磁性流体内行波磁场和力场的耦合问题,通过仿真和实验研究验证了设计的合理性和可行性。结果表明,行波磁场作用下的磁性流体流量与磁场的强度有直接关系:在磁性流体行波泵结构和磁性流体饱和磁化强度相同的条件下,磁场强度越强,其流量越大;当磁场强度从25 900 A/m增加到40 000 A/m时,单位时间内从行波泵内流出的磁性流体的体积由1.9 ml增加到3.1 ml;随着磁场强度的不断增加,磁性流体流量的变化率由于磁场对其粘度的影响而减小;而磁性流体的饱和磁化强度越大,其流量也越大。 相似文献
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剪切屈服应力是反映磁流变液流变特性的主要参数之一,稳定可控的磁场直接影响磁流变液剪切屈服应力的测量精度,因此磁场设计是否合理对磁流变液的流变性能测试具有重要的影响。针对外置式线圈产生的磁场强度较低且存在漏磁现象、对称式线圈中磁流变液装载不便导致测量过程持续性差等问题,设计了一种凹字型磁路,通过调整线圈位置来改变磁场结构,使磁力线垂直穿过磁流变液流动方向,同时可拆卸的组合式磁路设计在保证磁场强度需要的前提下实现了磁流变液的连续性测量。此外,还分析了不同电流下的磁场强度分布规律,并基于优化的磁路开展了磁流变液剪切屈服应力等力学性能参数的测试。与主流标准测试仪器相比,具有凹字型磁路结构的磁流变液测试系统所测得的剪切屈服应力平均相对偏差值约为10%,重复误差在6.34%以内,说明该磁路结构是磁流变测试中磁场装置设计的一种可行方法。 相似文献
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针对电机轴承高速化载荷高的需求以及磁流体轴承具有的自润滑密封、可靠性高、高速、低摩擦润滑等一系列优点,对磁流体轴承在不同条件下的性能开展了研究。首先从理论上推导了磁流体粘度的相关公式,通过采用Matlab软件在外加磁场的条件下,对磁流体的粘度进行了修正,并给出了磁流体轴承润滑的粘温、粘压特性。其次,采用有限元分析方法设计了外加磁场,并对轴承内部的磁场分布进行了分析。研究结果表明,在外加磁场的作用下,磁流体轴承润滑的粘度发生变化,同时,相较于传统普通轴承,磁流体轴承的承载能力得到提高,能在高温、高速的工况下工作。 相似文献
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可吞式无线磁驱胶囊机器人在胃肠道内的诊疗效果与机器人受到的外部磁驱动力密切相关。本文建立了外部磁驱动力的理论模型,基于等效磁荷模型推导了两径向充磁环形永磁体相互作用的数学表达式,采用自适应递归式计算方法开展了数值计算。此外,发展了环形永磁体间磁力实时测量方法,并开发了磁力-间距同步测量仪器开展实验研究,且建立了3D环形永磁体有限元仿真模型。实验测量磁力-间距关系曲线与理论计算和有限元仿真结果吻合较好,误差小于4%,验证了理论模型和有限元仿真模型的准确性和可靠性。通过参数分析,揭示了胶囊机器人内置永磁体长度、厚度和体积对磁力的影响规律。研究结果为精准驱动胶囊机器人在胃肠道内运动奠定了理论基础。 相似文献
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磁性液体独特的二阶悬浮力可以替代固体弹性元件为倾角传感器的惯性元件提供一个柔性弹性力,能够极大提高倾角传感器的抗冲击性能,已经在石油勘探行业成功应用。为进一步提高磁性液体倾角传感器的灵敏度,基于磁性液体的二阶悬浮特性提出了一种新的结构和检测方法,对传感器中两个永磁体间磁场的空间分布进行了理论计算和仿真,并通过试验对比分析了在选定不同参数条件下传感器的静态性能,最终得到当侧向间隙为3 mm,磁性液体注入量为1.4 g时,传感器量程为0°~50°,线性度误差为1.004 7%,灵敏度为2.3 mV/°,分辨率为0.023°,重复性误差为3.18%,工作性能最佳,且该传感器性价比高,壳体用材环保,具有很好的实用价值。 相似文献
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太钢不锈钢钢管公司成功攻克了一项世界性技术难题,研发出全球第一支使用挤压机生产的W型钢,产品主要用于核电裂变反应堆的管道支架。为全面提高不锈钢管市场占有率和应用范围,W型钢作为AP1000第三代核电站汽轮机发电余热排出换热系统的支撑件用钢,一直是由热轧加焊接工艺最终成W型钢,一方面热轧成本较高,另一方面对厚壁材料也增大了焊接难度,且所承担的风险远远大于无缝件。 相似文献
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Magnetic fluid is first introduced into the traditional cantilever-beam senor. Based on the property of the cantilever-beam
and the novel controllable magviscosity of magnetic fluid, the output of cantilever-beam sensors is under control so that
the controllable output of the sensors can be realized. The mathematical model of the sensors is established and analyzed.
The dynamic control function and the following educational results, which include the two curves of the displacement ratio
and phase function with the different damping ratio and frequency ratio, are obtained based on the model. The result shows
that it is valid to realize the controllable output of the sensors by controlling the viscosity of the magnetic fluid, and
finally the expanded measurement range can be realized. 相似文献
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传感器是磁性液体的重要应用领域之一。为弥补现有磁性液体微压差传感器的不足,设计了一种新型的磁性液体微压差传感器,该传感器的复合磁芯由磁导率高的1Cr13和永久磁铁构成,磁性液体被吸附在永久磁铁的端部形成环状起到润滑和密封的作用,敏感元件采用1Cr13,转换元件采用对称线圈。当磁芯进入线圈后,使得线圈电感发生变化,电桥电路输出明显的电压信号。在此基础上,提出了回复力的线性程度和磁性液体环的耐压能力决定了磁性液体微压差传感器的量程范围,并通过理论推导、仿真分析和实验研究的手段证明了磁性液体环的密封耐压能力能够满足磁性液体微压差传感器的测量要求。该传感器体积小、成本低、便于安装,具有很强的实用价值。 相似文献
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Wang Zhaoxia Zhang Weimin Liu Hongguang 《Frontiers of Mechanical Engineering in China》2008,3(2):222-225
The magnetic leakage field distribution resulting from linear defects of a tube sample in the geomagnetic field is modeled
according to the magnetic dipole theory. The formula to compute the normal component of the weak magnetic field is deduced
based on the spatial distribution of the magnetic dipole. The shape and characteristics of the zero line (an important criterion
for magnetic memory testing) of the normal field is analyzed under different longitudinal magnetizations. Results show that
the characteristics of the zero line should be considered when the metal magnetic memory testing method is used to find and
locate the defect.
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Translated from Transactions of Beijing Institute of Technology, 2007, 27(147): 395–398 [译自: 北京理工大学学报] 相似文献
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Magnetorheological (MR) fluid is a type of a smart material that can control its mechanical properties under a magnetic field. Iron particles in MR fluid form chain structures in the direction of an applied magnetic field, which is known as MR effect, resulting in variation of stiffness, shear modulus, damping and tribological characteristics of MR fluid. As MR effect depends on the density of particles in the fluid or the strength of a magnetic field, the experiments are conducted to evaluate the friction property under reciprocating motion by changing the types of MR fluid and the strength of a magnetic field. The material of aluminum, brass, and steel are chosen for specimen as they are the most common material in mechanical applications. The surfaces of specimen are also observed by optical microscope before and after experiments to compare the surfaces with test conditions. The comparing results show that the friction coefficient increases as the strength of a magnetic field increases in regardless of types of MR fluid or the material. Also the density of particle in MR fluid affects the friction characteristic. The results from this research can be used to improve the performance of mechanical applications using MR fluid. 相似文献
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为研究磁流体润滑非接触式机械密封的磁场特性,运用Ansoft Maxwell数值模拟磁流体膜和密封环组成的密封系统的磁场强度和磁感应强度,分析磁流体膜厚和电流强度对磁场强度和磁感应强度的影响,用最小二乘法拟合磁流体膜的磁感应强度和电流强度的关系式。结果表明:磁感线在密封系统中形成了完整的“O”形回路,磁流体膜中的磁场强度最大,磁感线在磁流体膜中分布均匀,且垂直穿过磁流体膜;当电流强度恒定时,磁流体膜中的磁感应强度和磁场强度沿厚度方向可视为常数;随着电流强度的增加,磁流体膜的磁感应强度和磁场强度均增加。 相似文献