GB678536A - Improvements in or relating to operating arrangements for electric time switches - Google Patents

Abstract

678,536. Time switches. MIDGLEY, A. H. Dec. 6, 1950. [Aug. 3, 1950 ; Aug. 11, 1950 ; Sept. 4, 1950] Nos. 19446/50, 19983/50 and 21783/50. Class 38 (v). [Also in Group XXIV] An operating arrangement for a time switch for converting regular into intermittent movement comprises driving and driven members mounted on a common shaft and coupled by a helical spring around the shaft and fastened at its ends to projections on the members, the driven member being locked by a spring-loaded catch to stress the spring, the catch being released by the projection on the driving member to which the spring is fastened. In one arrangement, Figs. 1 and 2, the driving member is a gear wheel 2 rotatable about a shaft 3 to which is secured the driven member (a disc 4), the gear 2 and disc 4 having projecting pins 6, 5 on their adjacent faces, the ends of the spring 71 being hooked round said pins. On rotation of gear 2 by a motor (not shown), the spring drives disc 4 round until a spring-loaded pivoted catch 8 engages and holds the pin 5 to stop the disc. Further rotation of the gear stresses the spring until the pin 6 trips the catch so as to allow the spring to rotate the disc rapidly, the pin 6 being larger than pin 5 so that it is not engaged by the catch. The disc has a cut-away portion with a projecting tooth 4a which engages and rotates an eight-toothed Geneva wheel 10 through one step during the rapid movement of the disc, which is then again driven by the spring until locked again, and so on. The wheel 10 is rotatable on a shaft 9 carrying an eight-toothed pinion 12 meshing with a seventy-two toothed gear 16 on a shaft carrying switch-operating cams. Fixed to the pinion 12 is a plate 13 having notches at its ends engaged by parts 14a of a plate having downturned ends 14 engaging slots 11 in the wheel 10 so that rotation of the latter drives the pinion 12, and the gear 16 and pinion 12 may be adjusted in the same direction of rotation in 5 degree steps independently of the wheel 10, backlash of gear 16 being prevented by a spring-loaded member 16a. In a modification, Fig. 3, the catch 8 co-operates with a cut-away stepped portion 4<SP>1</SP>a on the circumference of the disc 4, the tooth 4a being replaced by a pin 18 on the outer face of the disc, which also carries a smaller co-axial disc 19 having a portion 19a cut-away adjacent said pin. The gear 16 carries three spring loaded pawls 23, Fig. 5, spaced apart by 115, 115 and 130 degrees (or 125, 125 and 110 degrees) angles and co-operating with a twenty-four toothed gear 24 fixed to the cam shaft. The gear 24 is thus driven at any time by only one pawl 23, but when the cams are adjusted through 5 degrees steps, there is always one pawl in position to take up the drive. In a further modification, Figs. 6 and 7 (not shown), the pin 18 on the outer face of disc 4 co-operates with an eight-toothed star wheel fixed to the shaft 9.