An electrical generator includes a magnet constrained to move relative to a conductor by a support structure, with a ferrofluid bearing providing an ultra low friction interface between the magnet and support structure. The assembly has a critical angle of displacement from a horizontal static position of less than 1 degree, and preferably less than 10 minutes. An electrical signal is generated in the conductor by the moving magnetic field.

Electrical generator with ferrofluid bearings

A dynamic magnet system, particularly useful for electrical generation, employs multiple magnets in polar opposition to each other and having a critical angle of displacement from a horizontal static position of less than 1 degree, to induce an electrical signal in one or more surrounding coils. The magnets interact with each other to yield multiple modes of oscillation and a greater range of response to applied inputs than is achievable with a single magnet system. A lubricant for the magnets is preferably a ferrofluid that establishes a static coefficient of friction between the magnets and their support structure less than about 0.02, with a viscosity less than 10 centipoise. The magnets can be oriented for movement in a primarily horizontal direction and are adaptable to numerous different kinds of support structures, including ring-shaped.

Multiple magnet transducer

An autonomous power source comprises a power harvester mounted on a movable structure. The power harvester includes a coil, a magnet, and a low-friction ferrofluidic bearing in contact with the magnet, arranged such that the magnet and coil move with respect to each other when the structure is in motion such that an electrical current is produced in the coil. This current is converted to power and stored in an energy storage system and is thus available to power electronic circuitry. The magnet and bearing are preferably enclosed within a closed linear or circular tube, with the coil mounted around the exterior of the tube. The power harvester and battery are combined with one or more sensors and a wireless transmitter to form a tire pressure monitoring system.

Autonomous power source

An electric motor including an integral ferrofluid bearing provides significant reduction in non-repeatable runout, stray flux, and audible noise over conventional motors using ball bearings. The motor includes a hub and a base, with the base attached to a tapered magnetically permeable shaft which defines an inner bearing race, and the hub attached to an internally tapered, magnetically permeable sleeve which defines an outer bearing race. Permanent magnets surround and are rotatable with the sleeve to provide mangetic fields which interact with the stator winding to cause rotation of the hub and sleeve. In addition, the permanent magnets form magnetic flux paths with the shaft and the sleeve to maintain ferrofluid lubricant between the inner and outer bearing races.

Electric motor with ferrofluid bearing

An electrical generator includes one or more magnets that move relative to one or more conductors to generate an electrical signal in each conductor. Each magnet has ferrofluid bearings in the vicinity of its opposite ends to provide a low friction interface between the magnet and a support structure. The ferrofluid bearings establish a field expansion medium that directs at least a portion of the magnetic field so that a greater portion of the field intersects the conductors than in the absence of the medium. The magnet aspect ratio is preferably on the order of unity.

Magnetic transducer with ferrofluid end bearings

A self-contained, full film hydrodynamic bearing is provided having a ferrofluid (colloidal suspension of magnetic particles) with magnetic properties which facilitates retention of the fluid within the bearing where the bearing retains the ferrofluid over a wide temperature range and concomitantly compensates for ferrofluid expansion and contraction.

R Tuffias

Papers

Ferrohydrodynamic low-friction bearing with improved volume compensation and fluid seal