Patent GB-372357-A (GB)
Title: Improvements relating to electromagnetically-operated electric circuit closing and opening devices
IPC: H01H50/70
Filed: 1931-02-05
Abstract: 372,357. Light current relays. SIEMENS BROS. & CO., Ltd., Caxton House, Tothill Street, London, and BRYAN, E. A., Winton Lodge Lane, Blendon, Bexley, Kent. Feb. 5, 1931, No. 3710. [Class 38 (v).] A contact spring set for electromagnetic relays or other electromagnetically-operated circuit-controlling devices has a resilient spring blade which carries a contact positioned at each end and bowed about a straight line between its ends, so as to have alternate bowed stable positions, a transient circuit closure being made when a contact spring is moved by the relay armature into contact with the bowed spring, continued movement of the armature snapping over the spring to its alternative bowed position to break this circuit, the transient circuit closure not being made on the reverse movement of the armature. As shown in Figs. 1 and 3, the bowed spring 11 is supported at its ends across a gap in a rigid bar 1. The spring 11 carries a contact at the mid-point of its lower surface which is normally just out of engagement with a contact carried by a spring blade 2. The blade 2 also carries a stirrup-shaped member 15, Fig. 2, the upper limb of which is fitted with a downwardlyextending insulating projection 16 over the mid-point of the spring 11. When the armature 14 is attracted, it engages the insulating projection 12 attached to the spring 2 causing the contact carried by this spring to engage the contact on the spring 11 and move the centre of the spring 11 upwards until it snaps over into its oppositely bowed position. During the movement of the spring 11 across its midposition a transient circuit closure takes place between blades 1, 2 after which the blade 11 moves away from the spring 2. During the return of the armature the projection 16 engages the upper side of the spring blade 11 and snaps it back, no contact being made between springs 2, 11 on the return movement. By a reversal of the positions of the insulating projection 16 and the contact spring 2, the momentary engagement of springs 2, 11 may take place during the return movement of the armature. In a further alternative arrangement, Fig. 6 (not shown), a second contact may be carried on the upper side of the bowed spring 11 and a co-operating contact may be mounted on a spring blade mounted above the spring 11 this contact being forced by the insulating projection 16 against the upper contact of the blade 11 during the return stroke of the armature, causing the blade to snap back to its former position. Thus a momentary contact with the upper blade is produced during the return movement. In a further modification, Fig. 4 (not shown), the spring 11 bears a second contact on its lower side normally in engagement with a relatively fixed contact carried by a stiff spring. On attraction of the armature the engagement of the contact carried by the spring 2 completes for a very short time a circuit between both pairs of contacts and this circuit is almost immediately broken at the second pair of contacts, contact being subsequently broken between the springs 2, 11 in the manner previously described as the blade 11 moves across its mid-position.