Affiliations: [a] School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing~100044, China | [b] State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
Correspondence:
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Corresponding author: D. Li, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China and State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China. Tel.: 86 10 51684006; Fax: 86 10 51685265; E-mail: dcli@bjtu.edu.cn
Abstract: The sealing of large diameter rotating shaft in some special applications especially in aerospace and military industry needs to be sealed with magnetic fluids. However, the major problems of restricting the application of large diameter magnetic fluid rotary seal is the decrease of the pressure-resistance capacity of magnetic fluid seal at high temperatures and the bigger breakaway torque at low temperatures. To research effect of the temperature on the pressure-resistance capacity and breakaway torque of large diameter magnetic fluid seal, a sealing device with the diameter size of rotary shaft for 190 mm and the sealing gap for 0.1 mm was designed. Through the experimental test studied on the pressure-resistance capacity at −55 °C–70 °C and the breakaway torque at −55 °C–20 °C, exploring the influence rules of injection volumes of magnetic fluid and the standing time on the breakaway torque under at −55 °C. The experimental results show that the decrease of the saturation magnetization of magnetic fluid at high temperatures result in the pressure-resistance capacity falls, and the increase of the magnetic fluid viscosity at low temperatures is the key factors which causes the bigger breakaway torque. In theory, the analytical expression of between the viscous drag torque and the temperatures were derived, which could qualitatively explain the experimental rules of between the breakaway torque and the temperature at −55 °C–20 °C. In addition, the breakaway torque of magnetic fluid seal increases as the addition of the standing time and eventually becomes stable at −55 °C, and between the breakaway torque and the injection volumes of magnetic fluid showed a linearly change.
Keywords: magnetic fluid seal, high/low temperature, large diameter, breakaway torque, pressure-resistance capacity
