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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]

A novel symmetrical embedded magnetic fluid seal (SEMFS) structure was designed with the aim of enhancing the pressure resistance of the magnetic fluid (MF) seal with small gap under vacuum condition. The magnetic field distribution in the sealing gap (SG) was studied by numerical simulation, and the theoretical pressure resistant-withstanding of the SEMFS was obtained by combining the pressure resistance theories of stepped MFS. An experimental study was conducted to investigate the effects of magnetic fluid injection volume (MFIV), number of pole teeth, SG, and rotational speed of the rotating shaft on the seal's pressure resistance. The pressure resistant-withstanding values obtained were compared with those theoretically projected for the (SEMFS) and the ordinary magnetic fluid seal (OMFS), based on numerical analysis. The results indicate that the measured pressure value for the SEMFS matches well with the calculated pressure value. Furthermore, the SEMFS exhibits superior pressure resistance capabilities compared to the OMFS when subjected to the same parameters, which fully reflects the superiority of SEMFS structure. With an augment in the injection volume of MF, the pressure-withstanding performance of the SEMFS exhibits an initial upward trend followed by a gradual stabilization. Moreover, the pressure-withstanding performance of the SEMFS demonstrates a progressive enhancement with an increase in the number of radial pole teeth (RPT) and a corresponding increment in the number of axial pole teeth (APT). The ability to resist pressure of SEMFS decreases as the radial sealing gap (RSG) and axial sealing gap (ASG) increase. At low shaft speeds, the SEMFS's pressure resistance capability is not impacted by rotational speed and can be considered similar to a static seal. • A novel symmetrical embedded magnetic fluid seal structure was designed. • A sealing test bench was designed to conduct experimental studies on the sealing performance. • The symmetrical embedded magnetic fluid seal structure exhibits superior pressure resistance capabilities compared to the traditional sealing structure. • The increase of the magnetic fluid volume will cause the sealing pressure resistance to rise first and then stabilize. • The more the teeth, the smaller the seal gap and the greater the pressure value. The low speed has almost no effect on the pressure resistance. [ABSTRACT FROM AUTHOR]