Recent Patents in Magnetic Fluid Seals and Applications

Magnetic fluid seal is a special kind of hermetical device. It seals gas or liquid by the sealing ring which is formed when magnetic fluid is placed in the designed strong magnetic field. Such seal has the advantages of simple design, low friction and zero leakage at almost any rotation speed. For better understanding the principle of magnetic fluid seal, some related knowledge of magnetic fluid is presented. On the basis of that, the principle and structure of typical magnetic fluid seal are introduced. Then, a review of the various types of magnetic fluid seals is presented. Its brief history is also reviewed. This is followed by retrospection of some latest patents and applications in magnetic fluid seals. The patents and applications concern a period extending from the years 2003 up to date. The patents principally concern innovative designs of magnetic fluid seal's structure and arrangement. The applications mentioned in this paper mainly focus on areas of high-tech, such as wafer treatment equipment, weber processing apparatus, immersion lithography, Xray apparatus, and so on. At last, a description of the future developments expected in magnetic fluid seal is concluded.