Structural design and parameter analysis of a modular magnetic fluid rotary seal for robot joints

The magnetic fluid rotary seal plays an extremely important role for robot joints working in special environments. In this work, a novel modular magnetic fluid rotary sealing structure is proposed, which has the characteristic of small width and inner and outer diameters that can be adjusted according to actual requirements. It can be used as an independent module to seal robot joints, showing great application potential for robots working in extreme environments. Firstly, according to the calculation of the critical pressure difference of the magnetic fluid seal (MFS) and the magnetic field simulation analysis, the selected position of the extreme value of the magnetic flux density was determined, and its accuracy was proven through experiments. Next, the magnetic field simulation analysis was carried out on the size parameters of the conventional MFS structure to obtain the selection range of relevant parameters. Finally, a new MFS structure was developed according to the selected parameters. The critical sealing pressure difference (CSPD) was compared with the conventional sealing structure through experiments, showing its advantages of small size, strong sealing capability, and excellent modularity.