Magnetic fluid sealing device

A magnetic fluid sealing device, comprising:

• a housing;
• a shaft rotatably penetrating through the housing;
• a first shaft sleeve made of a magnetic conductive material, a volume of the first shaft sleeve being configured to increase with a rise of a temperature in the housing, and the first shaft sleeve being fitted over the shaft;
• a plurality of pole shoes arranged in the housing and fitted over the shaft and the first shaft sleeve, an inner circumferential surface of the pole shoes being provided with a plurality of pole teeth arranged at intervals in an axial direction of the shaft, the shaft and a first part of the plurality of pole teeth being arranged at intervals in a radial direction of the shaft to form a first gap, the first shaft sleeve and a second part of the plurality of pole teeth being arranged at intervals in the radial direction of the shaft to form a second gap, a magnetic fluid having a base fluid with a small molecular weight is arranged in the first gap, a magnetic fluid having a base fluid with a large molecular weight is arranged in the second gap, the second gap being configured to be reduced with an increase of the volume of the first shaft sleeve, the second gap being greater than the first gap when the temperature in the housing is not higher than a preset value, and the plurality of pole shoes being arranged at intervals in the axial direction of the shaft;
• and
• a permanent magnet arranged in the housing and fitted over the shaft, the permanent magnet being arranged between two adjacent pole shoes.