GB172935A - - Google Patents

Abstract

172,935. Siemens & Halske Akt.-Ges. Dec. 11, 1920, [Convention date]. Electromagnetic switches; relays.-Closed circuit relays with a spring or gravity control are made sensitive to very short interruptions of the maintaining current by arranging that such interruptions cause a movement which brings about a disappearance or reversal of the holding- torque. The lozengeshaped armature 2 is pivoted at 3 between the shaped poles of an electromagnet 1, a spring 6 tending to rotate the armature in an anti-clookwise direction, Fig. 1. The magnetic flux normally passes longitudinally along the armature, traversing the low reluctance air gaps between the adjacent co-operating surfaces 4, 5, thereby ensuring a stable position which is unaffected by mechanical vibration. On a momentary current interruption any motion of the armature caused by the spring 6 increases the air gaps at 4, 5 and diverts the flux transversely across the armature, Fig. 2, destroying the magnetic holding torque. A stop 2 arrests the armature in this position. In a modified form, Fig. 3, motion of the armature on interruption of the current causes a diversion of the flux producing a reversal of magnetic torque, the torque in the second position, Fig. 5, assisting the controlling spring 6. The armature and core are arranged to work at comparatively low values of magnetic saturation so that the shifting of all the lines of force in the pole-pieces at a determined place can be more easily effected. A bridging contact 7 carried by the armature joins pairs of stationary contacts 8, 9 in the two stable positions of the armature. The spring 6 may be replaced by an equivalent gravity control.