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To investigate the failure mechanism of the magnetic fluid seal (MFS) with opposite pole teeth (OPT) in gas and vacuum environments, a sealing device was designed to directly observe the surface shape of the magnetic fluid film. The failure mechanism and sealing performance of the MFS-OPT in different environments were investigated and discussed with the ordinary MFS. Numerical analysis was conducted to study the magnetic field distribution of the sealing device. The self-healing ability of the MFS-OPT in different environments was investigated. The results indicate that the pressure transfer process of sealing device occurs in a step-by-step manner. When the sealing device fails, it will go through two consecutive stages of microleakage and complete leakage. On the other hand, when the ordinary MFS fails, it first goes through a bubble stage. The magnetic fluid in the sealing device leaks from the middle location of the opposing pole teeth. The sealing device exhibits higher pressure resistance in a gas environment than that in a vacuum environment. Both gas and vacuum environments have a higher pressure resistance for MFS-OPT compared to ordinary MFSs. • The MFS-OPT device can visualize the change of MF film shape. • In the MFS-OPT, the leakage channel occurs in the middle of the opposing PT. • In a gas environment, the gas bubbles are not produced by MF film during failure. • Pressure resistance and self-healing ability of the MFS-OPT are superior to the ordinary MFS. [ABSTRACT FROM AUTHOR]

To solve the problems of high leakage rate and short service life in vacuum equipment, a magnetic fluid reciprocating seal (MFRS) device was designed. A MFRS vacuum test bench was constructed for testing the leakage rate of seals. The effect of the magnetic fluid (MF) injection volume on the pressure resistance of the seals and the effects of reciprocating speed and reciprocating stroke on the leakage rate and the vacuum resistance of the seals were studied by experimental method. The results show that the optimum MF injection volume should be 2.5 ml, and the ratio of functioning MF injected to seal gap volume is 4.596. When the reciprocating shaft moves at a speed of less than 2.85 mm/s, the leakage rate varies in the order of 10−11 Pa m3/s. With the increase of the reciprocating speed, the vacuum of the sealing chamber first remains unchanged and then increases. With the increase of the reciprocating stroke, the vacuum of the sealing chamber first remains unchanged and then increases. The results of the study are of great significance for the design of reciprocating seals to meet the requirements of vacuum environment. • The magnetic fluid reciprocating sealing device is designed for vacuum equipment. • Design and construct the magnetic fluid reciprocating seal experimental bench for testing the leakage rate of seals. • The effects of reciprocating speed and reciprocating stroke on the leakage rate and vacuum tolerance of the seals were also experimentally investigated. [ABSTRACT FROM AUTHOR]

In order to enhance the pressure resistance of the ordinary magnetic fluid (MF) seal (MFS) with a large diameter shaft and large sealing gap, the converging embedded MFS (EMFS) device with a large diameter shaft and large sealing gap is designed in accordance with the principle of EMFS. A combination of numerical simulations and experimental studies is used to examine the effect of important factors such as the size of the sealing gap and the pole teeth (PT) number on the ability of the converging EMFS to pressure resistance. The findings indicate that the experimental pressure resistance of the converging EMFS with a large diameter shaft and large sealing gap is basically consistent with the theoretical pressure resistance. As the radial and axial sealing gaps increase, the pressure resistance of the converging EMFS decreases. With the increase of the number of radial PT, the pressure resistance of the converging EMFS first increases and then decreases. With the increase of the number of axial PT, the pressure resistance of the converging EMFS first increases, then decreases and then increases. The pressure resistance of the converging EMFS remains unchanged with the increase of the speed. • The converging embedded magnetic fluid sealing device with a large diameter shaft and large sealing gap is designed. • The effect of the size of sealing gap on the pressure resistance of the seal is studied. • The effect of the number of pole teeth on the pressure resistance of the seal is studied. • The designed sealing device has little effect on the pressure resistance of the seal at low speed. • This sealing device provides certain technical support for solving the problem of engineering machinery sealing. [ABSTRACT FROM AUTHOR]