US2021758A - Electric lamp - Google Patents

Description

No). 19, 1935. 1. H. VAN HORN ELECTRIC LAMP Filed Dec. 8, 1933 .Z'N YEN TUE TRYING .H'. 'SZAAIH .zazxz',

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Patented Nov. 19, 1935 UNITED STATES ELECTRIC LAMP Irving H. Van

Horn, East Cleveland, Ohio, as-

signor to General Electric Company, a corporation of New York Application December 8, 1933, Serial No. 701,452

5 Claims.

My invention relates to electric lamps and similar devices comprising a bulb having an energy translation element, or filament, sealed therein, and more particularly to fuses therefor. In

some instances the breaking of the filament in an incandescent lamp causes an arc to form therein which may result in the bursting of the bulb and the blowing of the main line fuse. In many cases the arc travels along the leads of the lamp into the base and socket structures, welding them together before the main line fuse breaks, thus causing considerable damage. It is desirable, therefore, to provide some means of cutting off the arc. A fuse in the lamp provides this protection, although, if it is exposed to the atmosphere by disposing it in the base as has been done heretofore, difficulties arise due to deterioration of said fuse. An object of my invention is to provide a fuse within the lamp enclosure which will be sufliciently quick acting to break the electrical circuit before the arc has affected the glass parts of the lamp. Another object of my invention is to provide a fuse structure which will prevent a second arc from forming after the first arc is cut off. My fuse is also applicable to other similar devices having an electrical energy translation element therein.

According to my invention, I provide a fuse which is interposed in the inner portion of a leading-in wire and consists of a wire considerably less in cross-sectional area than said leading-in wire. By disposing the fuse within the sealed glass enclosure of the lamp, allowance for deterioration need not be made, and consequently the fuse may be made more sensitive. This is particularly desirable in the higher wattage lamps from 300 to 1500 watts, as in these cases the fuse wire must be sufficiently large to carry the relatively large currents required and yet have the required sensitiveness. Arcing is more noticeable in this type of lamp, and since these lamps operate at considerably higher temperatures, a fuse which is exposed to the outer atmosphere deteriorates very rapidly. If the fuse wire size is increased to the point where no premature failures occur, then it becomes insensitive and the arc is not cut off before considerable metal has been thrown off onto the bulb, with a resultant possibility of an explosion. I also prefer to surround the fuse wire with a non-conductor so that after the circuit to the arc is once broken it may not start again from this point. The inner end of the leading-in 'wire in which the fuse is built is also preferably supported so it can not drop onto the bulb upon the failure of said fuse.

Other features and advantages of my invention will be apparent from the accompanying drawing and description which follows of species thereof.

In the drawing, Fig. 1 is a. side elevation of an electric incandescent lamp embodying my in- 5 vention; Fig.2 is an enlarged elevation of the fuse thereof; Fig. 3 is an enlarged elevation at right angles to Fig. 1 of a heat shield and adjacent parts of the leading-in wires; and Fig. 4 is a side elevation of a mulitple filament lamp em- 10 bodying my invention.

The incandescent lamp shown in Fig. 1 comprises a bulb l0 into which is sealed a glass stem II in a portion of which are sealed leading-in wires I2 and I3. Each of said wires is composed of a section M, usually of copper, connected to respective sections of the base iii, an intermediate section "5 of a special composition which seals into glass and an inner section l1, usually of nickel. The filament i8 is attached directly to the inner end of lead wire it but the inner portion of leading-in wire I3 is composed of three sections, l1, l9 and 20, the filament [8 being attached to the end of section 20. Sections l1 and 20 are preferably likewise composed of 25 nickel whereas section IS, the fuse, is composed of a wire of much smaller size, nickel or an alloy thereof having more strength being preferred. In order that section l9 will function as desired, the cross sectional area (see Fig. 2) must be considerably smaller than the remainder of the leading-in wire, as for instance, in the 500 watt lamp shown, the fuse section is of 14 mil diameter and the adjacent sections are each of 35 mil diameter. The fuse wire is .709 inch (18 mm.) 35 long.

The intermediate portion of the filament is supported by wires 2| the ends of which are embedded in the end of glass arbor 22 which extends from the stem II. A heat shield 23 is 4 preferably provided to reduce the temperature of the base. Said shield is preferably of mica and is held in place as shown in Fig. 3 by portions 24 of the leading-in wires which are bent into sideward extending Us. The end section 20 of lead- 45 ing-in wire I3 is also engaged by a support wire 25 which extends from arbor 22 and holds said section so securely that after the blowing of fuse IE it is supported thereby. A non-conducting shield comprising a glass tube 26 is preferably 50 located about leading-in wire I3 between the heat shield 23 and support wire 25. The tube 26 serves to quench the are which forms when the fuse is blown and prevents the said are from being transferred to the other leading-in wire. 55

The lamp shown in Fig. 4 differs from that Just described in that it has two filaments II and II,

a common leading-in wire I! and two other leading-in wires l2 and I1. One end of each of the filaments l8. I8 is connected to lead wire i3, while the opposite ends of said filaments are connected respectively to lead wires l2 and II. The fuse I0 is incorporated in the common lead wire It.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. An electric device comprising a bulb, an electric energy translation element in said bulb, a leading-in wire extending into said bulb, the inner end of said leading-in wire being connected to said energy translation element, a fuse disposed between sections of said leading-in wire in said bulb, and a non-conductive shield surrounding said fuse.

2. An electric device comprising 'a bulb, a electric energy translation element in said bulb, a leading-in'wire extending into said bulb, the

, inner end of said leading-in wire being connected to said energy translation element, a fuse disposed between sections of said leading-in wire in said bulb, a non-conductive shield surrounding said fuse, and means for-independently supporting the section of leading-in wire between said fuse and energy translation element.

3. An electric device comprising a bulb, an electric energy translation element in said bulb, a leading-in wire extending into said bulb, the inner end of said leading-in wire being conaoamse nected to said energy translation element, a fuse disposed between sections "of said leading-in wire in said bulb, a non-conductive shield surrounding said fuse, and means for independently supporting the section of leading-in wire'between I said fuse and energy translation element, said means also supporting said shield.

4. An electric device comprising a bulb, a plurality .of electric energy translation elements in said bulb, a leading-in wire extending into said 10 bulb, the inner end of said leading-in wire being connected to said energy translation elements, a fuse disposed between sections of said leadingin wire in said bulb, and a non-conductive shield surrounding said fuse.

5. An electric device comprising a bulb, an electric energy translation element in said bulb, a leading-in wire extending into said bulb from one end thereof, the inner end of said leading-in wire being connected'to said energy translation element, a fuse disposed between sections of said leading-in wire in said bulb, an insulating arbor extending axially into said bulb, a support wire extending from said arbor to the, section of leading-in wire between said fuse and energy translation element, a non-conductive apertured disc surrounding said arbor and attached to the section of leading-in wire between said fuse and the end of the bulb, and a non-conductive tubular shield surrounding said fuse and extending between said support wire and disc.

IRVING H; VAN HORN.

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