GB1504873A - Electromagnetic devices - Google Patents

Abstract

1504873 Electromagnets SIMMS GROUP RESEARCH & DEVELOPMENT Ltd 18 Feb 1975 [26 Feb 1974] 8606/74 Heading H1P An electromagnetic device comprises a pair of relatively movable magnetizable members, and a winding or windings carrying an energizing current to produce relative movement of the members; a magnetizable core member 10 (Fig. 1) being secured by a threaded stud to a support 11, and a cup-shaped member 12 retained by the stud locating a magnetizable annulus 13 about the core while permitting limited relative axial movement between the members which are mutually located by a sleeve 12a at the opposite end. Slots are provided exteriorly of core 10 and interiorly of annulus 13 in the form of, e.g. 2 start interengageable threads permitting mutual axial movement and defining helical slots 14, 15 of the core and interengaging helical projections 16, 17 of the annulus. Continuous insulated windings 18, 19 are disposed in one slot from the stud end to the sleeve end, through aperture 20, and back in a reverse direction along the other slot. The projections of the core and the annulus have respective radial side faces 21, 22 and inclined side faces 23, 24 which on de-energization are disposed adjacently in parallel to leave gaps therebetween. Energization of the windings generates an additive flux operative to urge the members together and to reduce the gaps between faces 21, 22; thereby producing a mechanical force. The windings may comprise two distinct turns in series or parallel (Fig. 3, not shown) or four turns (Fig. 6, not shown). The annular member may be lightened by machining off surplus material (Fig. 4, not shown) and the slots may be reduced in size and filled with copper (Fig. 5, not shown). A pair of multiple windings may be provided in each slot (Fig. 7, not shown) of which one is continuously energized to provide base flux and the other is selectively energized for operation. The windings may be disposed in the internal slots of the annulus as well as in the external slots of the core, with an annular member movable therebetween having projections positioned in the slots of the annulus and the core respectively (Fig. 8, not shown); the windings being energizable together for single action or separately for double action. The peripheral surfaces of the core and the annulus may be axially slotted to increase flux penetration. Two electromagnetic devices as described may be connected back to back for double action, and to reduce rotational torque two devices with helical threads in opposed directions may be connected to operate in the same sense.