GB1393608A - Bistable mechanism - Google Patents

Abstract

1393608 Spring units; spring power-storing mechanism INTERNATIONAL BUSINESS MACHINES CORP 3 Aug 1972 [27 Aug 1971] 36206/72 Heading F2S A mechanism consists of a rod, such as an armature 10, rigidly secured, as by nuts 16 on threaded rods 11 connected to its ends, to an inner edge of each of a pair of annular spring discs 12, 13, each with curved slots in the zone between its inner and outer edges (and arranged so that the slots of one disc are directed in the opposite sense to those of the other disc), the outer edges being secured to a fixed support (e.g. housing 14, by pole shoes 17, 18 and clamping pieces 19, 20), so that the rod can adopt either of two stable positions along its axis, e.g. against either of two adjustable end stops 24, 25. The springs 12, 13 are first clamped to the armature 10 at their inner edges and the outer edge of one spring, say 13, is clamped against the adjacent pole shoe 18 by the raised edge of the adjacent piece 20. The rod is then moved axially and is caused by spring 13 to rotate about its axis and thus rotate the spring 12 clamped to it. The outer edge of spring 12 is then clamped to the pole shoe 17 by the disc 19 by tightening of screws 23. Arcuate slots 21 in the spring 12 permit its rotation before the tightening of the screws. On removal of the axial force moving the rod, the latter returns to one of the stable end positions with a biasing and change in shape of the springs 12, 13. Now, upon axial force being applied to the rod (armature 10), e.g. by exciting a field coil 29, the rod is moved axially against the spring tension until it reaches a midposition and then rapidly passes the position because of spring force in the same direction; it moves to an end position against one of the adjustable stops 24, 25.