GB1468978A - Electromagnetic relays - Google Patents

Abstract

1468978 Electromagnetic relays SIEMENS AG 1 Aug 1974 [20 Sept 1973] 34026/74 Heading H1N A polarized electromagnetic relay has an armature contact changeover switching action with mono- or bi-stable positions depending on the relative reluctance of various magnetic flux paths. In Fig. 1 the armature 1 is elongate with one end freely rolling on a polepiece 2 attached to one pole of a permanent magnet 5 and the other end is electrically and magnetically engageable into a stable switched position with a first mating polepiece 3, there being a second mating polepiece 4 for armature engagement which extends from a core 8 of a winding 10 and a fluxguide element 9. Contact bounce is minimised by magnetically saturating the polepieces which have reduced cross-section at points such as 3a, 4a. In the monostable from flux # 53 from the permanent magnet 5 predominates to bias the armature 1 to the 2, 3 position unless it is overcome by the flux # 54 acting conjointly with energizing flux # 10 from the winding 10. In the bi-stable form a polarized pulse applied to the winding 10 is sufficient to switch the armature from one position to the other, in each of which it is then held by flux from the permanent magnet 5. In a bi-stable embodiment, Fig. 2, the same principle is followed, the armature being U-shaped for mechanical damping and sealed within a switching chamber 33 created by fusing the polepieces 12, 13 and 14 into a glass envelope, the contact components being mercury wetted. To diminish the reluctance of the flux path through the coil 18 a second permanent magnet 22 is provided and a flux guide plate 20 is shaped to lead in to a ferromagnetic cover 21 which has an insulating lining 31 as well as creating a shunt air gap control 23. For further control of the magnetic circuitry a shunt gap 25 for the main magnet 15 is provided by a temperature dependent shunt plate 24, a double diode 34 is provided to suppress voltage surges, and terminals such as 27, 28, 29, 35, 36 anchored through an insulating base 30 serve for making electrical connections. In another bi-stable embodiment (Fig. 3, not shown), but similar to Fig. 2 the second permanent magnet (38) is located outside the coil (18). Both the Fig. 2 and Fig. 3 embodiments can be converted to mono-stable form by reversing the magnetic polarity of the second permanent magnet from that shown.