GB874386A - Rotary solenoid - Google Patents

Abstract

874,386. Electromagnets. OAK MANUFACTURING CO. Dec. 1, 1959 [Dec. 1, 1958], No. 40759/59. Class 35. In a D.C. electromagnet whose armature is arranged to have a " corkscrew " motion, a short-circuited winding is disposed adjacent the energizing winding to delay the return movement of the armature. The device comprises a ferromagnetic core 15 and housing 10, and an armature 21 on a ferromagnetic shaft 20. Attached to the armature is a disc 26 between which and housing 10 are balls 29 in arcuate, inclined grooves, which translate axial armature movement into rotation. Also attached to the shaft is a return spring 30. Enclosed within the housing is an energizing winding 17 and a short-circuited single or multi-turn winding 31. This delays the decay of flux when the energizing winding is switched off, and its effect is to compensate for supply voltage variations by providing a longer delay when the voltage (and hence the initial flux) is high; under these conditions the " pull-in " time is less but the return time will be greater so that a uniform time for the whole on-off cycle may be obtained. To provide a fine adjustment a variable resistor 33 with or without a rectifier 34 is connected across either one of the windings. If across the energizing winding an automatic switch may be provided to switch it in during the return stroke only. Specification 602,812 is referred to.