US2158870A - Fusible material - Google Patents

Description

May 16, 1939. F, E. S TTER 2,158,870 I FUSIBLE MATERIAL Filed April 14-, 1938 lNVENTOR 5 5077727? BY mm ATTORNEY Patented May 16, 1939 OFFICE 2,158,$70 FWSBLE MATERIAL Frederic E. Sutter, West Caldwell, N. .l., asslgnor to Westinghouse Electric a Manufacturing llompany, of Pennsylvania East Pittsburgh,

1%., a corporation application ilpril ll, 193%, Serial lilo. 2ll2,lll

My present invention relates to incandescent electric lamps and particularlyto a fusible section which may be utilized in connection therewith to extinguish the lamp upon the occurrence of abnormal current how, and constitutes a continuation in part of my copending application Serial No. 125,545, filed February 13, 1937, and assigned to the same assignee as the present application.

It has long been the practice in the manufacture of incandescent electric lamps to employ a fuse in the base for the la'mpor preferably to form a fusible section as part of the leading-in conductor which supplies the electrical energy for the filament. Although considerable progress has been made in the manufacture of incandescent electric lamps, especially in the quality of the tungsten filament and the leading-4n conductors, there are, nevertheless, occasions when the filament becomes disrupted. This frequently causes the formation of an are which travels along the filament supporting and leading-in conductors. When this are continues for an appreciable pe rind of time occasionally explosion of the lamp occurs with possible resultingdamage.

in order to obviate such contingency it has been the practice to form a section of the leading-in conductor of a special fusible material having deiinite current carrying characteristics so that upon the occurrence of abnormal current flow disruption of the fusible section follows thus interrupting current flow and preventing the uncle-- sirable formation of an arc with possible detrimental results. liowever, several problems exist in connection with the selection of the proper fusible material as it must not only have the requisite current carrying characteristics but inasmuch as it is disposed in close proximity to the seal where the leading-in conductor passes through the glass envelope, it is preferable that it have a coemcient of expansion approaching that of the class envelope.

Moreover, since the fusible section must be of a material differing from that of the metal forming the leading-in conductor proper it must also be such as to be readily joined thereto by welding or soldering. Heretofore it has been customcry to utilize as a fusible section some alloy, such as that commonly known as fMagno which com prises approximately 95 per cent manganese and 5 per cent of nickel. Suchalloys, however, have been found objectionable, particularly for manu facturing purposes since they oxidize quite readlly necessitating thorough cleaning, before being joined tothe leading-in conductor, otherwise a an incandescent 'velope is ing rod ll (lCl. 2llll-l135) good soldered connection cannot be made. also, these alloys are exceptionally resilient which increases the dlfliculty of jolnlne to the leading-in conductor since they tend to sprint, away from r the leading-in conductor to which it is desired to 5 connect the fusible section.

it is, accordingly, an object of'my present invention to provide a fusible section for an electrical conductor which possesses the requisite current carrying characteristics and which may be readily joined to the remainder of the conductor proper.

Another object of my present invention is the provision of a fusible section particularly adapttable as a fuse for incandescentelectric lamps it and the lilre wherein the fusible section may be readily joined to the illament support and leading-in conductor during the process at manu iacture.

it further object of my present invention is the provision of a fusible section for a leadlne ln conductor for incandescent electric lamps termed oil a material which does not readily oxidise and which is readily cleaned by flour or the lilre thus lacilitatino joining to the leading-an conductor proper by soldering".

Still further objects of my present invention will become apparent to those chilled in the art by reference to the accompanylne draw-vine where in: 3Q Fig. i is an elevational view partly in section oi lamp constructed in accormnce with my present invention showing the fused section disposed interiorly oi the envelope, and

li'ie'. it is a view similar to trip. it but illustrates the fuse section disposed euterlorly oi the on velope.

Referring now to the drawing in detail it have shown in Fig. i an incandescent lamp of the usual till construction which comprises an evacuated en- 40 velope ii having" the customary screw base i ce mented or otherwise attached thereto. The enprovidedwith a reentrant press l and extending upwardly from this press is a supportto the extremity of which is secured a plurality of suitable wires ll ior resiliently sup porting a filament it so as to allow for contraction and expansion of the latter when heated to incandescence by the passage of an electrical current therethrough. Connected to the ends of the filament are a pair of leading-in conductors one of which it extends through the press 'l and is connected to the center contact point of the base Ii. The other leading-in conductor I3 is likewise connected to such as what is known as the opposite end of the filament and extends through the press I whereit is connected to the shell of the base 6. In order to prevent the heat from the filament affecting the seal at the point where the leading-in conductors l2 and I: pass through the press I, particularly in high wattage lamps, an insulated baffle or the like H is provided which is supported by small lugs attached to the leading-in conductors; The leading-in conductor l3 has a fusible section formed integral therewith which comprises a short length of wire or ribbon l5 formed of an alloy as hereinafter more fully described, which may be soldered to the remainder of the leading-in conductor. For the purpose of preventing hot metal from falling in the vicinity of the seal upon disruption of the fuse l5 it is surrounded by a sleeve of.insulating material IS.

The construction thus far described constitutes essentially an incandescent lamp provided with what is termed an inner fuse which has long been known to the art.- However, in accordance with my present invention I make the fuse of an alloy Lohm comprising approximately 93 per cent copper and 7 per cent nickel, or. "Monel which comprises approximately 60 per cent nickel, 33 per cent copper and 6.5 per cent iron with traces of other metals. Owing to the relatively high percentage of copper in combination with the nickel an alloy is formed which has the requisite electrical current carrying characteristics so as to be fused upon the passage of abnormal current flow. Moreover, these alloys become oxidized to a very slight extent thus facilitating soldering to the remainder of the easily cleaned by flux or the like, and inasmuch as these alloys are relatively soft they can be shaped and retained adjacent the surface which it is desired to contact thus making automatic machine manufacture of the-leading-in wire together with the fusible section practical.

In Fig. 2 I have shown a lamp similar in all respects to that shown inFig. 1 with the exception that it is of smaller wattage, being less than Fig. 2, so that it will become disrupted thus preleading-in conductor, since any oxidation is.

venting the energy from passing interiorly of the lamp which, because of the high wattage energy supplied might otherwise have a tendency to sustain the are rather than extinguish it.

It thus becomes obvious to those skilled in the art that I have provided a fusible section which can be readily employed as an integral part of a leading-1n conductor for an incandescent electric lamp. Inasmuch as the alloy which I employ not only has the requisite electrical current carrying characteristics but oxidizes very slightly and is thus easily cleaned by flux, or the like, and is sufficiently pliable as to be shaped as desired, it can be readily joined to the leading-in conductor proper which is naturally of a metal having a different coefficient of expansion.

Although I have shown and described one specific embodiment of my present invention I do not desire to be limited thereto as various other modifications thereof may be made without departing from the spirit and scope of the appended claims.

What is claimed is:

1. A fuse adapted to disurpt upon the passage of abnormal flow of electric current therethrough consisting of a slightly oxidizable, readily cleanable alloyincluding copper and nickel with each metal being present in excess of 25% of the total percentage of said alloy to render said fuse readily solderable to metals or alloys of a composition differing from said fuse.

2. A fuse adapted to disrupt upon the passage of abnormal flow of electric current therethrough consisting of a readily cleanable, slightly oxidizable alloy including copper in the proportion of 33% to 93% and nicke in the proportion of 60% to 70%, respectively, of the total percentage of said alloy to render said fuse readily solderable to metals or alloys of a composition differing from said fuse.

3. A fuse adapted to disrupt upon the passage of abnormal flow of electric current therethrough consisting of a readily cleanable, slightly oxidizable alloy including approximately 60% nickel, 33% copper and 6.5% iron and readily solderable to metals or alloys of a composition differing from said fuse.

4. A fuse adapted to disrupt'upon the passage of abnormal flow of electric current therethrough consisting of a readily cleanab1e,slightly oxidizable and pliable alloy including approximately 93% copper and 7% nickel readily solderable to metals or alloys of a composition differing from said fuse.

FREDERIC E. SUTTER.

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