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US 5,007,513 AGranted
Electroactive fluid torque transmission apparatus with ferrofluid seal
AssigneeLord Corporation
InventorJ. David Carlson
Life of this patent
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AssigneeLord Corporation
InventorJ. David Carlson
Estimating the term…
An apparatus for controlling the transmission of torque between drive elements using an electroactive fluid which is sealed within an enclosed chamber. A housing defines the chamber and includes at least one end defining an opening. Spaced electrodes are provided in the chamber in contact with the fluid and are respectively connected to the drive elements. A controllable power source applies a variable electric field to the fluid such that force is transmitted between the electrodes by the fluid according to the strength of the field. A shaft connects one of the electrodes to one of the elements and extends through the opening. A ferrofluid seal assembly prevents leakage of the fluid from the chamber through the opening. The assembly defines with the shaft an annular space in communication with the fluid. A magnetic circuit is provided in the assembly by a permanent magnet for applying a concentrated magnetic field in one or more regions across the annular space. A ferrofluid which is immiscible with the electroactive fluid occupies the regions as though it were a liquid O-ring, thus sealing the fluid within the chamber both when the shaft is stationary and when rotating.
Apparatus for controlling the transmission of force, said apparatus comprising first and second members adapted for relative movement, said first member defining a chamber and having a circular opening, said second member extending within said chamber in a spaced relation to said first member, an electroactive fluid disposed in the space between said members, a shaft extending from said second member and through said opening, the diameter of said shaft being less than the diameter of said opening to define an annular space, means for applying an electric field between said members and to said fluid for transmitting forces between said members by said fluid according to the strength of said electric field, a ferrofluid disposed in said annular space and immiscible with said electroactive fluid, and magnetic circuit means for applying a concentrated magnetic field in said annular space and to said ferrofluid to maintain said ferrofluid in said annular space as a seal.
Apparatus for controlling the transmission of torque, said apparatus comprising a housing defining a chamber and having at least one circular opening, first and second members extending within said chamber in a spaced relation and adapted for relative movement, an electroactive fluid disposed within said chamber, a shaft extending from at least one of said members and through said opening, the diameter of said shaft being less than the diameter of said opening to define an annular space, means for applying an electric field between said members and to said fluid for transmitting torque between said members by said fluid according to the strength of said electric field, a ferrofluid disposed in said annular space and immiscible with said electroactive fluid, and magnetic circuit means for applying a concentrated magnetic field in said annular space and to said ferrofluid to maintain said ferrofluid in said annular space as a seal.
Dependencies are inferred from the claim text.