GB514264A - Improvements in and relating to electric lamps and the like - Google Patents

Abstract

514,264. Two-part couplings ; fusible cut-outs. BRITISH THOMSON-HOUSTON CO., Ltd. April 28, 1938, No. 12725. Convention date, April 30, 1937. [Class 38 (i)] [Also in Group XI] An electric cut-out comprises a glass bulb or envelope 11 having metallic terminal contact members 12, 13 sealed directly within apertures in different portions thereof and an electric energy translation element 16 directly or indirectly connected at its ends to the contact members 12, 13. The filament 16 is secured to support wires 14, 15 spot welded to the contacts or thimbles 12, 13 which may be formed of chrome iron and are sealed in the bulb 11. The bulb 11 is evacuated through an orifice 17 in the thimble 13, a small quantity of solder, soft melting glass, Khotinsky wax or cement or like fusible material 20 arranged inside or outside thimble 13 being subsequently heated to seal orifice 17. The inside, diameters of the neck portions 21 are made large enough to permit the thimbles 12, 13 to slide freely into position and are fused thereto by heating, pressure being applied to the plastic glass if desired, to effect a tight seal. In another arrangement, Fig. 10, the thimble 13 is first sealed to the lower neck of bulb 11, the filament being attached to the support wire on the thimble 12 and carrying a support wire 15 at its other end. A bead of solder 26 or other conducting fusible material is provided on the wire 15 so that when thimble 12 has been fused to neck 21 and the bulb evacuated the thimble 13 is heated and the bead 26 melts to close orifice 17 and connect wire 15 to thimble 13. Fig. 12 shows a thimble provided with a tongue 28, 29 to eliminate the use of filament support wires. In a further arrangement, Fig. 14, the thimbles 12, 13 are arranged in the bulb 11 with the openings outwards as shown. Thimble 12 is sealed to bulb 11 which is evacuated through the space in neck 21 around thimble 13. The neck 21 may be originally formed as a tube 31 which is used as an exhausting tube and is finally cut or cracked off at the outer end of the thimble. Fig. 16 shows a vacuum chamber 32 exhausted througb tube 35, leads 36 being arranged to supply heating coil 38 which is energized to effect sealing of the orifice in the thimble when evacuation is complete.