Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – Work or object holding type
Reexamination Certificate
1999-11-22
2001-05-08
Donovan, Lincoln (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
Work or object holding type
C335S291000, C335S285000
Reexamination Certificate
active
06229422
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a switchable holding magnet system and more particularly to a system which employs permanent magnets but can be switched from a holding state from a non-holding state.
While various systems have been proposed in which a holding magnet system powered by permanent magnets can be switched from a holding to a non-holding state, these prior art systems have been relatively complex and difficult to assemble and or energized. Typically, these prior art systems have involved magnets of different types with coils around only the magnets of one type.
Among the several objects of the present invention may be noted the provision of a novel holding magnetic system which is switchable between holding and non-holding states; the provision of such a system which can be electrically switched between the holding and non-holding states; the provision of such a system which is simple to construct and to energize; the provision of such a system which is easy to assemble; the provision of such a system which is highly reliable and which is of relatively simple and inexpensive construction. Other objects and features will be in part apparent and in part pointed out hereinafter.
SUMMARY OF THE INVENTION
In the switchable holding magnet system of the present invention, a central pole piece provides a central pole face. A magnetically permeable frame provides a peripheral pole face at least on either side of the central pole face together with a backing plate bridging the central pole piece. Between the backing plate and the central pole piece are provided a first, switchable permanent magnet and a second permanent magnet, the second permanent magnet having an energy (H
c
) which is substantially higher than that of the first permanent magnet. A coil surrounds the first and second permanent magnets inside of the peripheral pole face. Accordingly, energization of the coil in one direction can reverse the polarization of the first magnet and thereby effectively short circuit flux produced by the second magnet and terminate holding. Correspondingly, energization of the coil in the opposite direction can polarize the first magnet in parallel with the second magnet thereby to effect holding.
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Dike Bronstein, Roberts & Cushman LLP
Donovan Lincoln
Manus Peter J.
Walker Magnetics Group, Inc.
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