GB920292A - Improvements in and relating to magnetic circuits - Google Patents

Abstract

920,292. Electromagnetic relays. R. E. H. CARPENTER. April 6, 1961 [April 11, 1960], No. 12886/60. Class 38 (5). In a magnetic circuit including a winding on a ferromagnetic bobbin the end plates of the bobbin have outer surfaces of part-spherical form which engage corresponding surfaces of polepieces of a relay. The polarized relay shown has its winding on a ferromagnetic bobbin (Fig. 4) comprising a stem 23 and cheeks 24, 25 having part-spherical outer surfaces which engage co-operating recesses in limbs 13, 17 of respective ferromagnetic polar brackets 12, 16. The other limbs 14, 18 of the brackets 12, 16 are located and secured in spaced relation by screws 19 and non-magnetic spacers 20, 21. The screws 19 pass through elongated holes in the limb 18 so that during assembly the limbs 13, 17 can be pressed against the cheeks whilst the screws 19 are tightened ensuring good magnetic joints irrespective of manufacturing differences in the brackets or bobbin. The radius lines 27, 28 of the cheek faces extend from different centres allowing offset of the bobbin due to manufacturing tolerances. A flat armature 33, 34, 35 between opposed faces of the polar brackets 12, 16 has a permanent magnet 33 and two polepieces 34, 35. The armature is pivoted on its end shafts 38, 39 which pass through the spacers 20, 21. A moving changeover contact is carried on an arm 47 secured to an extension 42 of the shaft 38. Specifications 809,441 and 920,293 are referred to.