GB162673A - Improvements in or relating to electro-magnetic relays or like devices - Google Patents

Abstract

162,673. Automatic Telephone Manufacturing Co., Ltd., (Assignees of Erickson, J.). May 6,1920, [Convention date]. Electromagnetic and magnetic actuation.-Relates to relays, for use in automatic telephone systems &c., in which the relay is provided with a main armature and an auxiliary member or armature, so arranged as to enable the main armature to take up one of two stable attracted positions, corresponding to comparatively strong and week energizing currents, whereby one or other of two switching operations is performed by the armature. Figs. 1 and 3 show one form of relay comprising a core 2 with a pair of windings, supported by a heel-piece 3, which also carries the contact springs. The main armature 4, which is pivoted at 5, is perforated over the centre of the core to receive a rivet-shaped auxiliary armature 13 of soft iron, having a brass sheath 14. The enlarged head 12 of the auxiliary armature 13 is arranged to move within a housing 8 secured by screws 9, 10 to the main armature. When the core is feebly energized, the main portion of the flux passes through the auxiliary armature, which is attracted to the core, thereby closing a secondary magnetic circuit, which renders the attracted position a stable one, and as the auxiliary armature carries the main armature, the centre contact spring is forced out of engagement with its resting contact. The secondary magnetic circuit through the armature 13 includes the air gap formed by the brass sheath 14, and if the energizing current is steadily increased a critical point is reached at which the leakage from this magnetic circuit between the main armature and the core is sufficient to attract the main armature, thereby completing the second circuit, during which motion the auxiliary armature 13 moves upwards within the casing 8. In order to permit of adjustment of the air gap in the secondary magnetic circuit, the modified form of relay shown in Fig. 5 is employed. The main armature 34 only partially covers the end of the core, an L-shaped auxiliary armature 40 being secured by non-magnetic rivets 45, 46 to a non-magnetic member 42 pivoted coaxially with the main armature 34, the lower end of rivets 45, 46 resting on the main armature 34. An iron screw 41 passes through the auxiliary armature 40, an adjustable gap separating its lower end from the main armature 34, and spring washers 44, 45 retaining the screw 41 in its adjusted position. As the gap Between the auxiliary armature 40 and the core is smaller than that between the main armature 34 and the core, the relay operates in the manner above-described.