MAGNETIC FLUID SEALING DEVICE

摘要

PURPOSE:To reduce the loss of a magnetic fluid due to its evaporation by forming an oil repelling film on the side surface of a yoke and the surface of a shaft in proximity of a minute gap between the yoke and the shaft. CONSTITUTION:An oil repelling film 4 is formed on the side surface of a yoke 1 and the surface of a shaft 2 in proximity of a minute gap between the yoke 1 and the shaft 2, said oil repelling film being more effective when it is made of a fluorocarbon polymer such as Teflon and the like but can be of other material. Thus a magnetic fluid 3 is held only in the minute gap between the yoke 2 and the shaft 2 and the area of the magnetic fluid 3 in contact with the surrounding air is substantially reduced as compared with the conventional magnetic seal. The force which holds the magnetic force also becomes stronger as it is only held in the minute gap between the yoke 1 and the shaft 2 where the magnetic flux density is high.