GB772036A - Improvements in electromotors - Google Patents

Abstract

772,036. Electric motors. ANTHONY, J. March 3, 1955 [March 4, 1954], No. 6330/55. Class 35. [Also in Group XXXVII] An electric motor has two fixed field coils and an oscillating or rotating member carrying two permanent magnets arranged to co-operate with the coils and to actuate a magneticallyoperated switch to close the coil circuit as the magnets move past the switch. Figs. 1, 2 show a motor having two coils 7 and a pivoted rotating arm 6 carrying magnets 9 which actuate a magnetically operated switch 11. The latter, which is inserted in the coil circuit, has a rocking arm 12 carrying at one end a permanent magnet 13 and at the other end a counterweight 14 which normally keeps the switch open. The switch magnet 13 has its N pole uppermost so that as the N pole of the magnets 9 is near the magnet, the switch is closed, thus 3 completing the field coil circuit. The interaction of the fields of the coils 7 and the magnets 9 causes the latter to be repelled in the direction of rotation. As the magnets 9 move away from the coils, the switch 11 opens under the action of the counterweight. The rotor speed may be adjusted by altering the position of the switch 11 relative to the path of motion of the magnets 9 and to the fixed coils 7. In a modification, the rotating member is weighted so as to follow an oscillatory movement. In a further modification shown in Fig. 3, only one permanent magnet 18 and one field coil 23 are used, the magnet 18 being mounted at the lower rear part of a display disc 19 which rests upon a fixed fulcrum bar 21.