US2336903A - Cutout for electric lamps - Google Patents

Description

I. H. VAN HORN C UTOUT FOR ELECTRIC LAMPS Dec. 14-, 1943.

Filed May 24, 1945 Fig; 1.

lnven'tor Irvin H. VanHor'n,

, by His A+Torne9 Patented Dec. 14, 1943 CUTOUT FOR ELECTRIC LAB/[PS Irving H. Van Horn, East Cleveland, Ohio, assigner to General Electric Company, a corporation of New York Application May 24, 1943, Serial No. 488,197

Claims. (01. 315-75) My invention relates in general to series electric incandescent lamps and other similar electrical devices comprising a filament or other electric energy translation element mounted in a glass enclosure such as a bulb. More particularly, my invention relates to cutouts for such series lamps and devices which operate to preserve the electrical circuit through the lamp. or device, upon failure of the filament or other element thereof, so that the other devices in the series circuit will continue to operate.

Cutout constructions for series lamps have been proposed heretofore in which the inner lamp leads are formed with closely spaced portions which are bridged by a film cut out element. With such a cutout construction, when the lamp filament fails during operatioman are usually forms between one end of the broken filament and one of the inner leads. Such arc then melts back the said inner lead in the form of a ball until either the ball contacts the other inner lead so as to short-circuit the lead-in wires, or until the heat of the arc is suificient to break down the insulating film on the cutout element.

Occasionally, however, such cutout constructions fail to operate in the intended manner. Thus, under certain conditions of service which may develop after failure of the lamp filament, an arc may form between the closely spaced portions of the lead-in wires which arc, because of the small arc gap and therefore the small amount of wattage involved, posseses insufiicient heat to effect the breakdown of the insulating film on the cutout element with the result that the arc continues to persist. Because of the inherent tendency of arcs to wander, the persisting arc may then travel past or beyond the cutout element to a point intermediate the cutout and the stem press where the arc gap is of greater length, as a result of which the arc may then possess sufiicient heat to melt away one or the other of the lead-in wires at a point between the stem press and the cut-out and thus render the cutout structure wholly inoperative. The arc may then continue down into the stem press and lamp socket, resulting in extinguishment of the circuit and possibly a damaged socket.

One object of my invention is to provide a cutout for an electric lamp or similar :device which is simple in construction and positive in operation.

Another object of my invention is to provide a cut-out construction for an electric lamp or similar device which will operate to preserve the electrical circuit through the lamp, upon failure of the filament thereof, 'under' practically all conditions which may develop within the lamp.

Still another object of my invention is to provide, for an electric lamp or similar device, a cutout construction of positive operating characteristics which does not require the forming of the inner lamp lead-in wires to a special shape. A further object of my'invention is to provide a cutout construction for an electric lamp or similar device which is capable of supporting an arc, and thus preserving the electrical circuit through the lamp, for an indefinite period of time. I 7

Further objects and advantages of my invention will appear from thefollowing description of a species thereof and from the accompanying drawing in which: i

Fig. 1 is a front elevation of an electric incandescent lamp provided with a cutout structure according to my invention; Fig. 2 is a plan View on an enlarged scale of the cutout structure of the lamp shown in Fig. 1; Fig. -3 is a vertical section on the line 3-3 of Fig. 2; and Fig. 4 is a perspective view of the cutout structure-comprising my invention. i

Referring to the drawing, the electric incandescent lamp there shown comprises a glass bulb it having a base H secured thereto and a mount structure 12 sealed therein. The said mount structure comprises a re-entrant glass stem I3 having-a press portion I4, a pair of lead-in wires l5, l5 sealed in the press portion M of the stem and connected to the terminals of the base H, and an electric energy translation element or filament it connected to'the inner ends of the lead-in wires I5. The inner portions ll of the lead-in wires, immediately inward of the stem press l4, extend more orless parallel to one another and are spaced the usual distance apart (in the lamp shown, around i% or thereabouts). I a 1 Mounted on theinner leads ll, immediately adjacent the stem press I4, is a cutout structure I8 according to theinvention. The said cutout structure comprises a pair of like "metal holder clips or stampings l9formed from suit able strip material andsecurely fastened tothe inner leads IT, at opposite points thereon, with their flat or planar surfaces extending vertically. For this purpose, one-end of each stamping" I9 is formed with" a vertically-extending loop or eye portion 20 which extends the-full "vertical length of the stamping'and which is pinched tightly around the inner lead I! to thereby securely fasten 'the stamping or clip in place on the said inner lead. The other end of each stamping I9 is notched, as indicated at 2|, to provide an extension or ear 22 of reduced vertical extent. The stampings or clips iii are mounted on the inner leads 11, one in aninverted position with respect ,tothe other, so as to vertically space the extensions, oneabove the other, a"slight distance apart such as, for instance, inch or thereabouts.

Carried by. the metal holder clips l9 and conwidth with the ears or extensions 22 thereof necting the extensions 22 thereon is a film-type 1 cutout element 23 preferably in the form of a short length of aluminum wire having a coating 24 of aluminum oxide extending over at least a portion of its length, preferably over the upper half or so as shown in the drawing. The insulating film or coating 24 is of such a character as will not break down at or somewhat'above the operatingvoltage. of the individual lamp elements in the series, but. which will. break down at a. voltage appreciably above the operating voltage of .theindividual lamp. elements, such as the; fullline voltage across the. series circuit.

Thus, where. a. group of twenty. lamps designed to operate. atj..30 .volts. are connected in. series acrossa. GOD-volt. current supply, the insulating V .film 24 on the cutout element. 23 is preferably of. such a. character as. will not break down below 40 volts or thereabouts The cutout element 23. may be. fastened in place. on themetal clips. I in any suitable man; ner which will. insure. theinsulation. of the inner leads I"! from one another by the oxide. coating Zionthe. cutoutelement. Preferably, however, the; free. endslofth'e ears. or extensions 22 on theclips I19 are .formedinto. loops. or. .eyes which are verticallyv alignedgwith. one another. -The..wire cutout .elementnZB. extends. through the. eyes. 25,..and. the-saidseyes. arepinched or closed around the wire..element, to. thereby securelyfasten, the. latter in. place within the metal clips. l9. The;-wire .cutout element 23.. is preferably disposedtwithin the. aligned loops. or eyes. 2,5..withthe. coated end portion 24; thereof positioned within one of the. eyes and .thebare 0.1: uncoatedend thereof. positioned ,withi'nthe other of said. eyes... Onlythe eye 25. enclosing theiuncoated end of the. wire .cutout.element is pinchedtightly thereonto to hold the wire. element in place flwithin. themetal clips [9; The other eye 25, enclosing. the. coated end of the wire cutout elementis. merely closed loosely therearoundso. asnot. to. scratch. or otherwise injurezthe oxidecoating 24. and thus cause a premature breakdown 0f...the cutout.

To enable the application. of. the cutout structure l8. to. lamps provided with. a glass arbor. extending inwardly. from the stem press Ht between: the. inner leads I], and further, to

compensate for variations in the spacing. of the inner leads I! of different lamps, those'piortions of. the metal clips-l9. between the inner leads .I'!

are preferablyoffset laterally from the plane of the. inner leads, as by bending. the metalclips or stampings. I9 into. amodifiedJZ-shape as .viewed in plan. (Fig. 2);. Such lateral. offsetting of the clips ,l9 thus provides clearance for the glass arbor with. which. the lamp may be provided.

The metal c1ips,l.9;should;beof such, propor tions and of such; material. as to readilysupport for an indefinite period. of time, without melting, any are that, may ,form therebetweenduring lam seryice. In otlienwords, the. meta1i 1ips around or so in width.

. In operation, the cutout I8 will not function as long as the filament It remains intact, inasmuch as thesoxide film 24 on the cutout element. 23 acts as an insulator at the normal operating voltage of the lamp. However, ifthe filament I6 fails when cold (i. e., when the lamp is notin operation), the cutout element 23 then operates when the circuit switch is subsequently closed. The fullivoltage of the line being then impressed across. the film cutout element 23, the insulatingfilm 24 thereon is punctured and a conductive path thus provided between the leadin' wires l5, 15. This allows the other lamps of the-series to light up and at the same time shows up the defective lamp.

Should the filament l-fi fail when hot (i. e., during operationof the lamp), an are forms between the broken filament and one or the other of the inner leads [1. This are then melts the said inner lead back in the-formof a molten ball as aresult of which the arc travels down to the cutout structure it and effects, in the great majority of cases, the breakdown of the insulating film 24 on the cutout element 23. In the event the arc should. fail to so break down the insulating film 24' on the cutout element 23, the arc will. then persist between the metal clips I9, particularly between. the closely adjacent loops or eyes 25 of the said clips. Because of the adequate heat-dissipating capacity of the metal clips, however, the-said clips. will therefore support the arctherebetweeh for an indefinite period of time without melting or becoming otherwise damaged. Furthermorebecause of the. relative closeness to one another of tlie'eyes 25 on the metal clips. IS, the. arc: will. tendto persist therebetween rather than travel. down or past the 'cutout. structure i8. and: onto: those exposed portions of th inner leads I? intermediate the stem press M. and. the metal. clips. H]: where itmight melt. away one or the. other of the inner leads Hat such point and thus render the cutout structure 18:.who1ly inoperative. To further gu'ardagainst such. acondition arising,the metal clips. I9 are; mounted, 'onthe inner leads [-1 as close. as. possible to. the stem press I 4 so. as to leave as. little as: possible of. the inner leads ex:- posed between the stem press! landl the. metal clips.,|9.. The; lateral oifsettin'glof the metal clips l9 between the. inner leads l'l: is of particular utility in. this connection inasmuch as it: per mits the meta-lv clips. to be mounted on the inner leads below the top or crown: 26- (Fig; 3) ofthe stem press l4: and immediately adjacent the point on thefstem press where the said: leads extend therefrom. so that thereare very little, i'f a'ny, exposed sections of the inner leads intermediate the stein press and. the metal? clips ill to which sectionsthe arccan strike. 7 .What Iclaim as new and desire to secureby Letters Patent of the United States is: 1'. An electric. incandescent lamp comprising a bulb;:a:.fi1ament.disposed within said bulb, a p'air of lead-in wires extending into said bulb and connected to said filament, a pair of metal holders secured one to each of said lead-in wires and having portions closely spaced from one another, and a film cutout element carried by said holders and in contact therewith, said holders being constructed and arranged to support, for an indefinite period of time without melting, any are that may form within the lamp during service upon failure of the filament thereof.

2. An electric incandescent lamp comprising bulb having a re-entrant stem provided with press portion, a filament disposed within sai bulb, a pair of lead-in wires sealed in the stem press and having inner lead portions extending into th bulb from the said stem press and connected to said filament, a pair of metal holders secured one to each of said inner leads at points thereon as close as possible to said stem press and having portions closely spaced from one another, and a film cutout element carried by said holders and in contact therewith, said holders being constructed and arranged to support, for an indefinite period of time without melting, any are that may form Within the lamp during service upon failure of the filament thereof.

3. An electric incandescent lamp comprising a bulb having a re-entrant stern provided with a press portion, a filament disposed within said bulb, a pair of lead-in Wires sealed in the stem press and having inner lead portions extending into the bulb from the said stem press and connected to said filament, a pair of metal holders secured to and enclosing appreciable lengths of said inner leads immediately adjacent said stem press and having portions closely spaced from one another, and a film cutout element carried by said holders and in contact therewith, said holders being constructed and arranged to support, for an indefinite period of time without melting, any are that may form within the lamp during service upon failure of the filament thereof.

4. An electric incandescent lamp comprising a bulb, a filament disposed within said bulb, a pair of lead-in wires extending into said bulb and having inner lead portions connected to said filament, a pair of strip-like metal holders of appreciable width secured one to each of and along said inner leads and having extensions closely spaced from one another and provided with aligned loops, and a film cutout element extending through and in contact with said loops, at least one of said loops being pinched tightly around said cutout element to thereby support said cutout element in place within said loops.

5. An electric incandescent lamp comprising a bulb, a filament disposed within said bulb, a pair of lead-in wires extending into said bulb and having inner lead portions connected to said filament, a pair of strip-like metal holders of appreciable width secured one to each of and along said inner leads and having extensions closely spaced from one another and provided with aligned loops, and a film cutout element carried by and in contact with said holders, said cutout element comprising an elongated body of aluminum extending through and in contact with said loops, the portion of said cutout element within one of said loops having a coating of aluminum oxide thereon and the portion of said cutout element within the other of said loops being free of such coating, said one loop being only loosely clamped and said other loop being tightly clamped around the cutout element.

IRVING H. VAN HORN.

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