GB1002574A - Polarised electromagnetic relays - Google Patents

Abstract

1,002,574. Electromagnetic relays. AMERICAN MACHINE & FOUNDRY CO. Dec. 18, 1961 [Dec. 28, 1960], No. 45355/61. Heading H2B. In a polarized electromagnetic relay having two windings on parallel magnetic cores with a parallel permanent magnet between them, an armature pivoted at one end of the permanent magnet is arranged to be normally biased to only one of the cores. As shown in Fig. 1, the cores 3, 4 and longitudinally polarized permanent magnet 9 are mounted on a magnetic return member 8 and the permanent magnet retains the armature 13 on its knife-edge 11. Fig. 1 shows the armature attracted to the core 3 and engaging a non-magnetic spacer 6 when the coil 1, 2 are energized to assist the permanent magnet flux in core 3 and oppose that in core 4. On de-energization the contact spring 24 moves the armature clockwise to a position where it engages the core 4 which does not project so far from the member 8 as does the core 3 with its spacer 6. The armature is retained in this position by the permanent magnet which then has its face 10 closer to the armature 13 than its face 10 is as shown. The core 4 may be of equal length to the core 3 with its spacer 6 (Fig. 5, not shown) and with this arrangement the knife edge is offset as shown in Fig. 7 to provide the magnetic bias. In Fig. 8 (not shown) the magnet top is flat and the armature pivots on a pin above the flat magnet end. Fig. 9 shows an armature 42 pivoted at 41 and biased by a magnet pole 45 which projects toward one of the cores 44. The non- magnetic spacer 43 is shown mounted on the other core end but in all the arrangements described the spacer can be mounted on the armature end instead of on the core 3.