Ferrofluidics Corporation

Philip Stahl

Ronald Moskowitz

Walter R Reed

Dudley D Fuller

Donald F Wilcock

Thomas J Black, Jr

Harry C Rippel

A composite ferrofluid bearing and seal apparatus which comprises a ferrofluid seal apparatus which contains disposed therein a bearing element, to form a ferrofluid-film bearing with the surface of a shaft, the ferrofluid seal apparatus retaining the bearing ferrofluid film within the bearing cavity, by forming a ferrofluid O-ring seal, held by magnetic flux, at each end of the bearing element, the composite ferrofluid bearing and seal apparatus acting to contain the bearing ferrofluid film within the fluid-film bearing cavity and to exclude gases from being entrained in the ferrofluid.

Ferrofluid bearing and seal apparatus

A ferrofluid thrust and radial bearing assembly for a rotatable shaft element, which assembly comprises: a housing characterized by a shaft-receiving space, to define a radial bearing inner surface and a thrust bearing surface at the one end of the shaft-receiving space; a shaft element within the shaft-receiving space, one end of the shaft element disposed to rotate on the thrust bearing surface, and the other end of the shaft extending from the other end of the housing; a ferrolubricant in the shaft-receiving space, to form a lubricant for the thrust bearing and the radial bearing assembly; and a ferrofluid exclusion seal at the other end of the housing and about the other end of the shaft-receiving space, the exclusion seal comprising an annular permanent magnet and at least one annular pole piece, one end of which extends into a close, noncontacting relationship with the exterior surface of the shaft, to form a radial gap, and the ferrofluid within the shaft-receiving space defining a ferrofluid seal at the other end and about the shaft element, so as to retain the ferrofluid within the shaft-receiving space of the housing during the bearing operation.

Ferrofluid thrust and radial bearing assembly

A self-activating ferrofluid seal apparatus and method, which seal apparatus comprises a permanent-magnet ring and a pair of pole pieces which form a cavity therebetween, and which seal apparatus includes magnetically permeable, extending elements in the cavity to form a ferrofluid-retaining gap therebetween, the pole pieces forming a radial gap with the surface of the shaft to be sealed, the ferrofluid-retaining gap having a magnetic-field intensity sufficient to retain the ferrofluid therebetween and sufficiently larger in gap width than the radial gap, whereby, on insertion of the shaft element, the ferrofluid, based on the change in magnetic flux path, will move from the retaining gap to the radial gap to form a ferrofluid seal about the shaft element.

Self-activating ferrofluid seal apparatus and method

A ferrofluid centrifugal seal and method of sealing a rotatable shaft, wherein ferrofluid is retained in an O-ring-seal form at static and low speeds and is moved to a barrier seal in a passageway at high speeds.

Ferrofluid centrifugal seal

A seal for rotatable shafts utilizes a ferrofluid as a sealant and lubricant. As a sealant, the ferrofluid acts to exclude particulate matter from passing through the seal area contaminating internal mechanism elements, while as a lubricant, the ferrofluid forms a film between the shaft and the elastomer-material seal element; thus, cooling and lubricating the contact interface and acting to extend the life of the related components. The seal assembly has permanent magnetic elements which create a magnetic-field gradient, causing magnetic-field maxima at points immediately surrounding the contact point between the seal-elastomer material and the shaft. The ferrofluid is entrained magnetically within the interface region; thus, insuring continual lubrication of the contacting surfaces, while further, the entraining forces prevent leakage of the ferrofluid from the region.

Dynamic lip seal using ferrofluids as sealant/lubricant

A viscous-fluid inertia damper, which damper comprises a housing composed of a nonferromagnetic material and having a chamber therein, a seismic mass containing a permanent magnet disposed in the housing chamber and in a closely spaced-apart relationship with the internal wall surface of the chamber, means to couple the housing to a dynamic element whose energy is to be dampened, and a ferrofluid of selected viscosity in the remaining volume of the chamber, the ferrofluid distributed generally uniformly in the volume, the magnetic saturation of the ferrofluid by the magnetic field of the permanent magnetic levitating the seismic mass in the damper, and the viscosity of the ferrofluid in the magnetic field providing a means to dissipate energy from the dynamic system through viscous shear forces in the ferrofluid disposed between the wall surface of the chamber and the seismic mass.

Growing community of inventors

Holliston, MA, United States of America

Philip Stahl