US1217289A

US1217289A - Cartridge-fuse.

Info

Publication number: US1217289A
Application number: US84647414A
Authority: US
Inventors: Alfred L Eustice
Original assignee: Economy Fuse & Manufacturing Co
Current assignee: Economy Fuse & Manufacturing Co
Priority date: 1914-06-22
Filing date: 1914-06-22
Publication date: 1917-02-27
Anticipated expiration: 1934-02-27

Description

AfL. EUSTICE.

CARTRIDGE FUSE'. APPLICATION FILEDJUNE22.1914.

Patented Feb.27,1917.

27 26 J9 J9 2g 25 UNITED sTATEs PATENT oEErcE.

ALFRED L. EUS'IICE, OF CHICAGO,

ILLINOIS, ASSIGNOR T ECONOMY FUSE sa MANU-- FACTURING COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF NEW YORK.

CARTRIDGE-FUSE.

Specification of Letters Patent.

Patented Feb. 27, 1917.

Application led .Tune 22, 1914. Serial No. 846,474.

-inclosed fuses, used for the protection of electricv circuits, andv is particularly (although not exclusively) concerned with fuses of the so-called renewable type.

It is one of the objects of my invention to so construct a cartridge fuse that it is unnecessary to employ in said fuse a non-conducting illing material of any kind. Heretofore 1t has been customary to employ within the casing of the fuse a non-conducting filling material either in the form of a powder, such as lime, plaster of Paris, asbestos, or a filler in the form of fibrous material, such as a woven asbestos sleeve, or the like. I have found that in an inclosed fuse having my improved link which is hereinafter described, the use of a filling material of any kind may be avoided by so constructing an inclosed fuse that on blowing the fuse the gases which are generated are restricted in -their passage from the casing. The principle which I employ in restricting the escape of the gases is much the same as that employed in the well-known automobile mufiiers, Maxim silencers, and other similar devices which deaden the noise of an explosion by restricting the path of escape of the generated gases.

In the present application my invention is describedV as applied particularly to fuses of the so-called knife-blade type, in which the terminals project into the ends of the inclosingfcasing of the fuse. These terminals are suitably alined and centered, and a resilient closing member is provided to prevent the escape of gases directly through the ends of the fuse, the restricted paths for the escaping gases being formed between the screw threads on the ends of the, casing and those in the end caps of the fuse.

A further object of my invention consists in reducing to a minimum the amount of metal which is volatilized on blowing of the fuse, and I accomplish this result by prol viding the fuse link (which is preferably flat) of the cartridge or other inclosed fuse with a'plurality of restricted or substantially more quickly melting portions, these restricted portions preferably being formed by notching the sides of the link, and thus substantially reducing the cross-sectional area of the link at these portions. In this manner, on blowing of the link within the inclosed fuse the melting and volatilization of the metal occurs only at the restricted portions of the link, and the portions of the latter between such restricted portions vare instantaneously separated from the balance of the link and are not melted, thus greatly reducing the amount of gases generated by the blowing of the fuse. I ordinarily employ two restricted portions of the link near the ends thereof so that the greater portion of the link is caused to drop and separate itself from the balance of the link on blowing the fuse. In the case of fuses for high voltage circuits I preferably increase the number of restricted portions in the link, thereby correspondingly reducing the voltage at each restricted portion; for example, if a link is provided with two restricted portions, and is blown on a circuit of 500 volts, the voltage at each restricted portion will be 250 voits. If, on the other hand, five restricted portions are used in the link` the voltage at each restricted portion will be decreased to 100 volts, and the number of separate pieces resulting from the blowing of the fuse will, of course. in each case be one less than the number of restricted portions. Thus, in a link with two restricted portiogs a single piece will be separated from theV link; with three restricted portions two pieces will be separated, and so on.

I am aware that fuse links for use in the open air have been heretofore made with a plurality of restricted portions, but I have found that the operation of such links is entirely different from the operation of my im proved inclosed fuses, inasmuch as practical tests have demonstrated that under shortcircuit conditions links of the former type are completely melted or volatilized and sustain an arc for a` considerable period, while under the same conditions my improved inclosed fuses open the circuit instantly and the metal between the restricted portions of the links is separated without appreciable melting from the rest of the link.

Although in the present specification I have described the link ci my inclosed fuse as having a plurality of restricted or more readily melting portions and as being used ployed with hlling material.

A further object'of my invention consists inthe use of a dat fusible link orl only slightly less width than the interior diameter ot the cylindrical fuse casing. By thus using a link of relatively great width, and by increasing this width and the interior diameter of the casing as the capacity of the fuse is increased, means are provided for preventing the use in a fuse casing of a fuse link which 4is 'ot greater capacity than that for which the fuse is rated.

These and other objects of my invention will be more readily understood by reference to the accompanying drawings, in which- Figure 1 is a longitudinal section through my improvedtuse;

Fig. 2 is a longitudinal the line 2-2 ot Fig. 1;

Fig. 3 is a transverse line 3-3 ot Fig. 1;

Fig. t isa perspective of the uselink section taken on the used in my improved fuse; and

Fig. 5 is an enlarged fragmentary longitudinal section of the end ot the fuse casingyshowing a portion of the cap applied thereto. A

The cylindrical fuse casing 10 is preterably of fiber or other suitable non-conducting material, and is provided at its ends with the threads 11. The terminals 12 eX- tend into the ends ot the casing 10, and are alined and centered in position by means of tia the washers 13, which are preferably ot1 the same type as ydescribed in Letters Fatent No. 1,092,498'is'sued to Edward B. Mallory, assignor to lEconomy Fuse & Manufacturing (Company, on April 7 1914. Outside of the washers 13 at'each end of the fuse casing is placed another washer 14:, preferably ot resilient material, such as leather, rubber, or the like. The washers 14 are provided with apertures ot' ysubstantially the same size as the inner ends ot the terminals 12. Just outside of each of the washers 1111 1 preferably employ a metallic washer 15, which is identical in shape with the washers 1li, and is provided with asimilar aperture 16 ot substantially the same size'as the inner portion of the terminal 12. lin assembling the fuse, the washer 15 is rst placed in pos1- tion by slipping over the inner end oi-a the 'terminal'.12 until it is brought into engagement with the shottlder'17 on vsaid terminal. The leather washer 1t is next placed in positionin the same manner, and the washers 13 are then placed on the terminal by passing their tongues through the aperture18 in the terminal in the manner described in the Mallory patent above mentioned.

Flach oit the terminals 12 and its assosection taken on narrate ciated washers, which have just been descrlbed, 1s held in position by means of the end cap. 19, which has an interiorly threaded skirt engaging the threads 11 on the end of the casing 10. Each end cap 19 is provided with an inwardly extending flange 20, which engages the washer 15 so that on screwing home the cap 19 the inner washer 13 is brought firmly in contact with the end of the casing 10, while at the same time the washer 14C is pressed firmly against the outer washer 13 and against the terminal 12. At the same time the flange 20 of the cap 19 has a lirm engagement with the washer 15, thus edectually closing the end of the casing 10. A restricted path of escape for the gases which arev generated on blowing of the -`fuse is formed by the clearance between the threads 11 of the casing 10, and the interior threads on the skirt of each end cap 19. This clearance is clearly represented in Fig. 5 by the spaces 21.

The link which is used in my improved fuse is preferably flat, and is preferably of a readily fusible metal, such as zinc. This link, represented in the drawings by 22, is fastened to the inner ends of the terminals 12 by coperative action of the screws 23 and the nuts 24. The link 22 is provided near its ends with the notches 25, thus forming the restricted portions 26 of substantially reduced cross-sectional area and an intermediate portion 27 of substantially greater current-carrying capacity than said restricted portions. This intermediate portion 27 of the link is only slightly narrower than the interior diameter of the cylindrical casing 10, and is correspondingly thin in order to give the requisite cross-sectional area of metal for any given capacity of fuse. By making fuses of dierent capacities of correspondingly diderent widths, it becomes impossible to insert in a given tuse casing a link of greater capacity than that for which the fuse was designed.

1t will be revident from the above descrip tion that on blowing of the fuse the link 22 will melt at the intermediate portion 27 of the link will drop out of or become separated from the latter without volatilization of the metal of said intermediate portion. The `gases which its restrictedy portions 26 and prior open link fuses having a plurality of restricted portions.

After blowing of the fuse the' terminals 12 are readily removed by irst removing the caps 19, a new link is fastened to the inner ends of the terminals, and the fuse is then again assembled, as indicated in Figs. 1 and Q.

It will be apparent to those skilled in the art that'many changes could bemade in the detailed construction of the various parts which I have described without departing from the spirit or scope of my invention.

-lVhat I claim is:

1. In an inclosed fuse, the combination of an inclosing casing, terminals carriedby said casing,land a fusible link extending through said casing and between said terminals, said link being provided along its length with a plurality of portions of substantially less current-carrying capacity than that of an intermediate portion between said first-mentioned portions, whereby on the blowing of said fuse said link will melt at said portions of less current-carrying capacity and said intermediate portion will be separated from the rest of the link without melting said intermediate portion.

2. In an inclosed fuse, the combination of an inclosing casing, the interior of which has' restricted communication with the outer atmosphere, a pair of terminals carried by said casing, and a fusible link extending through said casing and between said terminals, said link being provided along its length with an intermediate portion of substantially greater carrying capacity than that of the portions of said link at the ends of said intermediate portion, whereby on blowing of said -fuse said link will melt at the portions located at the ends of said intermediate portion and said intermediate portion will be separated from the rest of the link without melting said intermediate portion.

3. In an inclosed fuse, the combination of a casing, a pair of terminals carried by said casing, and a fusible link extending through said casing and having its ends electrically connected with said terminals, said link having along its length a plurality of restricted portions of substantially less crosssectional area than that of an intermediate portion of said link between said restricted portions, whereby on blowing of said fuse said link will melt at said restricted portions and the intermediate portion of said link will be separated from the rest of the link Without melting said intermediate portion. l

l. In a cartridge fuse, the combination of a casing, terminals at the ends of said casing, and a flat fusible link extending through said casing and having its ends electrically connected with said terminals, said link being provided along its length with an intermediate portion of substantially greater cross-sectional area than the portions of said link at the ends of said intermediate portion, whereby on blowing said fuse said link will melt at the portions located at the ends of said intermediate portion and said intermediate portion will be separated from the rest of said link without melting said intermediate portion; c

5. In a cartridge fuse, the combination of a cylindrical casing, terminals at the ends of said casing, and a fiat fusible link extending through said casing and between said terminals, said link having along its length a pair of portions of substantially less current-carrying capacity than that of an intermediate portion between said first-mentioned portions, said intermediate portion being of a width only slightly less than the interior diameter of said casing.

6. In a cartridge fuse, 'the combination of a cylindrical casing, terminals carried by the ends of said casing, and a flat zinc link extending through said casing and lbetween said terminals, said link having along its length a plurality of portions of substantially less cross-sectional area than that of an intermediate portion between said firstmentioned portions.

In witness whereof, I hereunto subscribe my name this 16th day of June, A. D. 1914.

ALFRED L. EUSTICE.

Witnesses:

HENRY M. HUXLEY, f .H. C. JACOBS.