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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]

To solve the problem of low pressure resistance of the conventional ferrofluid seal (FFS) under the condition of single magnetic source with large gap, which is difficult to meet the demand of vacuum sealing, the convergent FFS with stepped pole piece structure was designed. The designed structure is also compared with the conventional FFS structure. The effects of radial and axial sealing gaps (SGs), number of steps, step height on the pressure resistance and self-repairing ability of the seal were experimentally investigated. The results show that the new FFS structure can withstand 1 atm when the number of steps is 4 and the radial SG is 0.4 mm, which can provide a reference for vacuum sealing. The innovative FFS has a maximum pressure resistance 23 times higher than the conventional FFS for the same size. The self-repairing ability of the seal is negatively correlated with the radial and axial SG, the number of steps, and the height of the steps. The results of this study are important for the design of the FFS structure with single magnetic source that meets the requirements of a vacuum environment. • The ferrofluid seal with the stepped pole piece is designed. • The maximum pressure resistance of the new ferrofluid seal is 23 times higher than the conventional ferrofluid seal under the same size. • The purpose of this study is to provide a reference for the design of vacuum seals that can withstand 1 atm. [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]