US Patent 11174946 Magnetic fluid seal

A magnetic fluid seal includes an outer cylinder member that houses therein a rotating shaft extending from a housing of a fluid machine, magnetic pole members housed in the outer cylinder member, disposed around the rotating shaft and forming a magnetic circuit, and sealing films to be formed from magnetic fluids, in an axial direction, in magnetic connection with the magnetic circuit, and between the magnetic pole members and the rotating shaft. The magnetic fluid seal further includes a gas supply passage that allows a gas to flow from an outside toward the magnetic pole members.