GB752489A - Improvements in or relating to spring mechanisms - Google Patents

Abstract

752,489. Springs. ABBEY, A. (Glaser, L. B., and Votta, F. A.). April 22, 1954, No. 11630/54. Class 108 (3). [Also in Group X] A spring mechanism comprises a spring strip 40 (Fig. 7) fixed to one (41) of two relatively movable members 41, 42 which are spaced apart a distance greater than the thickness of the spring but less than the distance required for coiling of the spring, receiving means 45 provided in the other member (42) which allows a free end of the spring to coil (as at 44) when the free end engages the means 45. Thus when the spring 40 is in the position shown in Fig. 7, it can exert no force between the members. When the member 42 is moved to the right relative to the member 41, the end of the spring 40 is able to start coiling up in the recess 45. The action of coiling results in a spring force being exerted between the members 41, 42. In Fig. 7, there are two springs 40 and 43, one 43 being fully coiled when the other 40 is fully retracted, and vice versa. One spring may, however, be mounted on the member 42, its corresponding recess being in the member 41. The two springs may be replaced by a single spring anchored at its mid point to the member 41, the recesses 44, 45 being disposed respectively beyond the free ends of the spring. In Fig. 3, the members 41, 42 are replaced by members 20, 22 which have rotary, instead of rectilinear, relative movement. The spring 29 is anchored at its mid-point to the member 20. Rollers 27, 28 are provided on pins 25, 26 in recesses 23, 24 upon which the spring 29 is adapted to coil. The distance between each free end of the spring and the corresponding recess, determines the degree of free relative movement of the members, the spring action not occurring until one of the free ends picks up its corresponding recess and is so able to start coiling. Alternatively, a predetermined degree of free relative movement may be provided by making the distance between the recesses less than the length of the spring. The spring is thus coiled in both recesses when the centre of the spring is disposed midway between the recesses. The force exerted by each spring is then equal and opposite, until one spring or the other (according to the direction of relative movement) is retracted from its respective recess. The spring may be of duralumin, beryllium copper or phosphor bronze. Where two springs and respective receiving means are provided, one receiving means may be of larger diameter so as to provide a spring force larger than that of the other. The invention may be applied to sliding doors (see Group X), circuit breakers and switches, and to machines having reciprocating or oscillating control elements for changing direction.