Patent ID: 6512435
Filing Date: 2003-01-28
Classification: E05B,H01F,H01H

Abstract:
A bistable electromagnetic actuator, comprising:only one electrical coil of wire turns, wound on an annular bobbin of non-magnetic material, forming with the bobbin a coaxial coil assembly, affixed in a first mass portion of said actuator and configured with an open cylindrical coaxial passageway, the first mass portion comprising a generally tubular soft iron shell containing said electrical coil and the bobbin disposed coaxially in the shell extending from an end region to a mid region thereof; only one permanent magnet, producing a magnetic field of flux lines, located coaxially and secured in a second mass portion of said actuator, the second mass portion constituting a generally cylindrical armature comprising a generally cylindrical permanent magnet having poles at first and second opposite ends thereof respectively, the ends being configured coaxially with corresponding first and second soft iron pole plates, each having a circular rim, the second mass portion being made and arranged to be slidingly movable relative to the first mass portion, in a stroke of axial direction and predetermined length; a magnetic yoke system, made and arranged to conduct a preponderance of the flux lines in a flux loop path that traverses said permanent magnet in series with said yoke system, the flux loop path including a primary working magnetic air gap of predetermined separation distance interposed in series in the flux loop path, providing a region of high flux density traversing a portion of said coil, such that an electrical current applied to the coil winding causes a mechanical force to act on the winding portion located in the magnetized gap in a defined direction perpendicular to the wire turns in accordance with well known electromagnetic physics, the defined direction being made to substantially coincide with the designated stroke direction, said magnetic yoke system being made and arranged to cause said coil and said magnet to respond to current of a first polarity and of sufficient amplitude by relative movement between said magnet and said coil, so as to drive a designated driven mechanical payload within the stroke length from a first stroke-end to a second and opposite stroke-end; and conversely, to respond to such current in a second and opposite polarity by moving from the second stroke-end to the first stroke-end; and a guidance sleeve of non-magnetic material secured coaxially within said shell and having a cylindrical-shaped interior surface, made and arranged to confine the relative movement between the two mass portions to a substantially straight line stroke path and to constrain said armature radially while allowing said armature to move relative to the first mass portion of said actuator in an axial direction and over a designated stroke length; said magnet and said yoke system being made and arranged to cooperate in a manner to magnetically hold the first and second mass portions together as a common mass at each of the two stroke-ends with said coil unpowered and thus provide bistability.