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US 5,969,589 AGranted
Quiet ferrofluid solenoid
AssigneeFerrofluidics Corporation
InventorKuldip Raj
Life of this patent
Estimating the term…
Abstract
A solenoid includes a ferrofluid in gaps between the moving and stationary elements which ferrofluid reduces noise caused by activating a plunger positioned within the solenoid. A permanent magnet can be included as a solenoid element to increase magnetic field strength within the solenoid to retain the ferrofluid within the solenoid.
Claims22
A solenoid comprising:
- coil apparatus for generating a magnetic field along an axis;
- a magnetic plunger positioned within the coil and moveable along the axis;
- a mechanical butt for limiting the axial movement of the plunger;
- a ferrofluid located between the plunger and the butt;
- and
- a gas located between the plunger and the butt that is vented to atmosphere past a magnetic seal formed by the ferrofluid as the plunger moves toward the butt.
3 more elements
A solenoid comprising:
- a casing formed from a magnetic material,
- a pole piece formed from a magnetic composition, said casing and pole piece being joined to form a housing having an internal volume,
- an electrically energizable coil positioned within said internal volume,
- a support means for said coil formed from a nonmagnetic composition, said support means having a core volume,
- a moveable plunger positioned within said core volume and extending through said housing,
- a stop means positioned within said core volume for limiting axial movement of said plunger,
- a ferrofluid positioned within said core volume between said stop means and said plunger and between said plunger and said support means, and
- a gas located between the plunger and the stop means that is vented to atmosphere past a magnetic seal formed by the ferrofluid as the plunger moves toward the butt.
5 more elements
Dependencies are inferred from the claim text.