GB1381654A - Control device for an electric switch or a fluid valve - Google Patents

Abstract

1381654 Linkwork; valves E J WEBER 5 April 1972 [31 May 1971 21 March 1972] 15579/72 Headings F2K and F2V [Also in Division H1] A control device for a microswitch 78, Fig. 1, or fluid pressure valve is operated by a sensing means such as a fluid pressure diaphragm 6, 18 via a rocking plate 42 having first and second axes (A) (B), Fig. 2 (not shown), about which it pivots sequentially against a pair of light and heavy biasing springs 52, 53, at least one of which is adjustable and having their lines of force intersecting a respective one of the axes. The arrangement is such that on operation a microswitch 78 or the like having a very small differential movements between the "on" and "off" positions may be given a large adjustable differential where the springs 52, 53 are respectively "light" and "heavy". The rocking plate 42 engages a fixed stop 50 at its intermediate position corresponding that between the "on" and "off" positions of the switch and at which the rocking plate 42 changes its pivot axis from one (A) on a pair of balls 46 (48), Fig. 2 (not shown), to act against a light spring 52 to another (B) on a pair of balls 47 (48) to act against the heavy spring 53. The balls 46, 47, (48) are in a triangular formation, Fig. 2 (not shown), and have their movements limited between top and bottom plates 20, 50. A resilient connection between the plate 42 and a push rod 84 for the switch 78 is provided by a "U"-shaped leaf spring 86. In a modification Fig. 9, the fluid pressure diaphragm 6 acts at the centre of a double armed lever 150 which initially pivots about one end 160 against the action of an adjustable light tension spring 153 coupled at the other end 173. Movement continues until the end 173 engages a fixed abutment pivot 171 so that further movement of the lever continues by pivoting about the pivot 171 against the action of an adjustable heavy tension spring 152 at the opposite end 160. A large adjustable differential for the force applied to the lever 150 is thereby obtained for the actuation of the switch or valve 78.