Vee-shaped magnetic/centrifugal seal and method of operation

Abstract

A combined magnetic/centrifugal seal for a rotating shaft rotatably journalled within a housing. The rotating shaft has a generally circular cross section and at least one radially extending generally Vee-shaped cross section circumferential portion formed about its periphery. A plurality of radially extending circumferential teeth are concentrically arrayed around the periphery of the rotating shaft in parallel relationship to the Vee-shaped circumferential portion on the rotating shaft on at least one of its sides and spaced closely adjacent thereto. The housing has a complementary generally Vee-shaped cross section within which the Vee-shaped circumferential portion of the rotating shaft rides and in conjunction with the Vee-shaped cross section portion defines a space within which the concentrically arrayed circumferential teeth extend. A magnetically susceptible ferrofluid is disposed within this space for forming a centrifugal seal during high speed rotation of the shaft and the ferrofluid communicates with the gaps formed between the ends of the concentrically arrayed circumferential teeth and the opposite surfaces of the rotating shaft on each side of the Vee-shaped cross section circumferential teeth. A magnetic field is impressed across the gaps thus defined to form a plurality of magnetic seal stages with the shaft at standstill and at low rotating speeds.