GB1311842A - Electromagnetic actuator - Google Patents

Abstract

1311842 Electromagnets W N ELWOOD 28 April 1970 [26 Jan 1969] 58636/68 Heading H1P An electromagnetic actuator comprises cylindrical magnetic members 1, 2, 3 coaxially mounted in a housing 4; fixed members 1, 3 comprising MS pots (Fig. 2, not shown) containing cylindrical permanent magnets of lesser diameter and a solenoid in each annular gap; the open ends being closed by non- magnetic spacers. Movable member 3 comprises two similar pots and magnets mounted backto-back and fixed to a plunger 5 traversing bores of members 1, 3 and slidable in the end walls of the housing. With polarities shown member 2 is attracted by 1 and repelled by 2 in the position of Fig. 3A, and on current pulsing of the coils to reverse the magnetic polarities of members 1, 3 the member 2 moves to the position of Fig. 3C, extending plunger 5. Reversion to the original magnetic polarities restores the position of Fig. 3A. Alternatively the polarities of members 1, 3 may be maintained and that of member 2 reversed. The members whose polarity is maintained may have a coil or coils adapted to sustain polarity against demagnetization by proximity to the members whose field is reversible. The magnetic material of the members may be ferrite.