Patent GB-197445-A (GB)
Title: Improvements in or relating to automatic electric commutators or switches
IPC: G04F1/00
Filed: 1922-02-24
Abstract: 197,445. Dufour, M. Y. L. Feb. 24, 1922. Switches, quick-break; switches, latching and unlatching; retarding-devices. - A short-time lighting switch which on operation closes a circuit for a predetermined time comprises a rotary member 20 of insulating material which carries metallic bridging pieces 24 adapted to bridge adjacent pairs of fixed contacts 15 which are disposed in four recesses in an insulating base 1. Each fixed contact, Fig. 4, comprises two plates 14, 15, secured by a screw 16 to a pillar 17, thus forming contact jaws at both sides of the contact, each contact also serving as a stop to limit the rotation of the member 20. A hole 18 and securing screw are provided for the incoming lead. The member 20 carries a drum 21 attached thereto by lugs 30 and screws 31, the drum 21 containing a spring 34 having its ends secured to a hook 33 inside the drum 21 and a hook 35 on a fixed spindle 6 around which the members 20, 21 rotate. A handle 60 is adapted to rotate a sleeve 62 which has projections 63 engaging recesses 29 in the central perforation 30 of the drum 21. In a recess between the members 20, 21 is secured a dish-shaped member 36, Fig. 6, a spring 41 being connected between a hook 40 on the member 36 and a hook 32 on the outer rim cf the drum 21. The member 36 has two radially projecting arms 39 carrying curved pistons 45 working in cylinders 49. The cylinders 49 are secured in pillars 53, 54 fitting in recesses 3 in the base 1. The closed ends of the cylinders are provided with adjustable air leak valves 51. The pistons 45 have cup-leathers 47 at their ends and longitudinal channels 46 to facilitate the readmission of air on the return stroke. The switch member 20 has two projecting cam portions 25 and the tripping member 36 has two similar projections 37 with bent-over ends 38. Normally the member 20 is held by the lightly stressed spring 34 in a position in which the projections 24 of the contacts 22 bridge the upper and left-hand and lower and right-hand fixed contacts respectively, the slightly stressed spring 40 holding the hocked ends 37 of the member 36 against the projections 25, and the pistons 45 being at the outer end of their stroke. If the handle 60 is now turned 90‹ in a clockwise direction the switch member 20 is moved against theaction of the spring 34 until its projections 25 are held by fixed spring pawls 56. The members 24 now bridge the upper and left-hand and lower and right-hand pairs of contacts thus closing the controlled circuit. The member 20 in its rotation stresses the spring 40 but the member 36 can only follow at a speed determined by the leakage of air from the cylinders 49. When the member 36 has completed its retarded following motion its cam projections 37 disengage the pawls 56 from the projections 25, Fig. 9. and the spring 34 breaks the lighting circuit. The member 20 in its return engages the projections 38 and carries with it the tripping member 36, but as little resistance is offered to the outward stroke of the pistons 45, the return stroke takes place rapidly until arrested by the contacts 24 engaging pairs of fixed contacts corresponding to the open circuit position.