GB677273A - Improvements in and relating to pneumatically driven turbo-electric lamps - Google Patents

Abstract

677,273. Dynamo lamps. DAVIS & SON (DERBY), Ltd., J., DAVIS, W. H., and LUCAS, Ltd., J. Feb. 22, 1951 [Nov. 22, 1949], No. 29814/49. Class 39(ii) A dynamo lamp, of the kind embodying a generator driven by a compressed air turbine, is provided with a cut-out comprising a sealed chamber enclosing a movable contact member and having a flexible wall responsive to the internal pressure within the well glass or similar enclosure surrounding the lamp bulb, so that a reduction in the internal pressure due to the breaking or removal of the well glass produces movement of the cut-out to short circuit the generator. The turbine wheel and the rotor of the generator are mounted in a two-part casing 10, 11, compressed air being admitted through an aperture 12 in the lower part 11. The cutout is enclosed within an annular housing 30 which is held in an airtight manner against a packing disc 31 on the underside of the casing member 11 and has an inturned flange 32 at its lower end. A rubber diaphragm 35 clamped between the flanged end of the member 30 and a cover plate 36 supports, on its upper side, a metal disc 33 with a central stud 38 that bears upon the underside of a resilient contact blade 39 which is clamped at one end by screws 40 and co-operates with a fixed contact pin 41 adjacent to its other end. Normally the diaphragm 35 is distended upwardly by compressed air which is admitted to the interior of the well glass 16 and passes through one or more holes in the cut-out housing, so that the contact blade 39 is held away from contact 41 while the lamp is being supplied with current through contacts 45, 46; the edge of the metal disc 33 is then bearing against the annular flange 32. As soon as the internal pressure falls, due to any circumstances, the diaphragm 35 is relaxed and the contact blade 39 bears against contact pin 41 to short-circuit the generator.