The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 09, 1985
Filed:
May. 03, 1984
Hanumaiah L Gowda, Nashua, NH (US);
Kuldip Raj, Merrimack, NH (US);
Ferrofluidics Corporation, Nashua, NH (US);
Abstract
A high-pressure rotary seal apparatus with a radially-polarized permanent magnet, which seal apparatus comprises: a housing; a magnetically-permeable shaft to be sealed extending through the housing, the shaft characterized by a plurality of separate grooves or stages on the shaft; a radially-polarized permanent magnet extending about the shaft, at least one pole piece adjacent to and in a magnetic flux relationship with the radially-polarized permanent magnet and extending about the shaft, one polarized end of the polarized magnet and one end of the pole piece extending into a close, noncontacting relationship with the grooves on the surface of the shaft to form a plurality of separate radial gaps; ferrofluid disposed in the radial gaps to define a plurality of separate, spaced-apart ferrofluid O-ring seals about the surface of the shaft; and a generally cylindrical, magnetically-permeable keeper element extending about the other polarized end of the magnet and the other end of the pole piece in order to provide a magnetic flux circuit which extends between the radially-polarized magnet, the keeper element, the shaft, and the ferrofluid in the radial gaps.