US1491695A - Fuse - Google Patents

Description

Patented Apr. 22, 18924.

`UNITI-:D STAT-Es 1,491,695 PATENT' ori-fica. v

ARCHBALD GRTEVE, OF WESTPORT, CONNECTICUT, ASSIGNOR TO' CHARLES H. KEMPER, INC., OF WES'ITORT, CONNECTICUT, A CORPORATION OF CONNECTICUT.

'rusia n Y Application tied February 4, 1921. Serial No. 442,516.

To all whom it may concern.'

Be it known that I, ARCHIBALD GRIEVE, a subject of the King of Great Britain, residing at Westport, in the county of Fairfield and State of Connecticut, have invented certain new and useful Improvements in Fuses, of which the following is a specification. i My invention relates to electric fuses, and l particularly' to renewable cartridge fusesof the clip type. Among the objects of my invention may be particularly mentioned-- one, the provision of a construction in which a rated end ofthe fusestrip may be carried with safety te `exposed position on the interior of the fuse casing; two, an end construction in which there is but a single dey tachable member; three, aconstruction using a draw-up screw ferrule having means to prevent the escape of gases to the threaded area of the ferrule and its complementary part of the fuse casing; four, an end lconstruction in which a circuitous gas escape passa is. provided by the detachable ferrule e ement; five, a contact member freely vcarried by the end ferrule to lengage the bent-over end of the fuse strip, but having a swiveling connection with the ferrule so as to protect the fuse strip end "against, which it bears -from ru turing strains, and

at the same time aifor ing by its loose engagement with the ferrule a gas vent; six, various details of improved construction hereinafter'pointed oit or shown in the accompanying drawings2 in which- Fi 1 is a broken side elevation of a fuse in w ich my invention is embodied infone form, the end cap at the left-hand end of the fuse being shown detached' Figs. 2, 3 and 4 are dend elevation and sections, respectively, on the lines 2 2, 3-3 and 4-4,` Fig. 1; and

. Fig.. 5 is a longitudinal section at right lan les to Fig. 1.

n certain res ects the present construction is akin to t at illustrated in my application Ser. No. 442,515 filed herewith on the blade t fuse, although, like man is susceptib e of modification in various pari 5 ticulars, whilestill retaining the underlyin features to which .the invention is directe Asillustratively embodied in the construc- .tion shown in the accompanying drawing, the fuse comprises a tubular -casin 6 of liber, or other insulating material, avingis thus sufficient mechanical strength to withstand the strains imposed upon it on the blowing of the fuse.` At the opposite ends of the casing are metal bushings 7 and 8 having reduced lnecks, which are forced into the ends of the casing and riveted thereto at 9. These necks are `preferably externally serrated, notonly to grip the fiber casing me-v chanically, but also to prevent the escape vof gas through the joint, to the injury of the fiber, on the blowing ofthe fuse strip'.l Adjacent the shoulder 10 of the bushing, which abuts against the end of the casing 6, the bushing is threaded. at 11 to receive the detachable ferrule 12.

The slightly reduced cylindrical outer ends yof the bushing are provided with closure diaphragms 13 and 14, on which at 15 and .16, respectively lare pivoted shutters 17 and 18. The latter substantialll close the end openings 19 in the diap ragms 13 and 14,'-through which the opposite endsv vof thefuse strip 20 are passed to the exterior of the bushings. As will be noted from Figs. 2 and 3, the :portion of the shutter 80 voverlying the opening 19 isprovided with a straight edge 21, which in adjusted position, determined by the stud X, lies parallel to one edge of the opening 19, but spaced slightly therefrom to afford a narrow exit plassage y22', which is substantially filled e 'fuse strip as it passes out therethrough from the yfuse chamber. The shutterfis preferablyso shaped that. its margin 23dconforms to the contour of the bushing en In order to afford a suitable contact area,

vthe projecting ends of the fuse strip are angled over the straight ed es 21 of the shutters and overlie .the outer aces of the latter. At one end of the fuse the shutter is' notched at 24 tolpermit an extension 25 of the fuse strip to be turnedA back therethrough between the skirt of the ferrule 12 and the outer -face of the bushin i7, in which a lshallow groove 26 is forme in re ister with a continuation 27 thereof in the se casing to receive the'end of the fuse strip. The latter bears a ratin indication 28, which exposed on 't e exterior Aofthe fuse casing beyond the edge of the yskirtof the ferrule 12, and is readily observed by an f inspector. v v To prevent escapejof gases through the groove 26, 27, thelatter is of such width 110 not actually seal the passageway. Furthermore, the fit of the reduced end of the bushing with the inner tace of the skirt of the ferrule is as snug as possible, and may be readily made so tight that the escape of gas to the threaded area of the bushing and ferrule is rendered practically impossible.

It will be noted that the gases escape from the fuse chamber principally, if not entirely, at the narrow passage 22, through which the fuse strip emerges and thus has a restricted entry into the expansion chamber 30 formed between the end of the bushings and the end of the ferrule. i From this chamber 30, in which the gases are cooled by expansion, they escape through a circuitous passage in contact with metallic cooling surfaces. To effect this, on the closed end of the ferrule 12 is mounted a gas deliecting washer 32 of slightly less diameter than the internal diameter of the cap. On the outer face of the lwasher are formed channels 33, or other venting passageways, which lead to a central-orifice 34 in the end of the ferrule. not completely, obstructed by the retaining stud 35 on the washer, which passes through the orifice and is sufficiently headed up to secure the washer to the ferrule end while nevertheless affording the play in the orifice necessary to permit the latter to functionas a gas escape passage. This stud may be integral with the washer, as indicated, or it may be an independent member passing therethrough and riveted in position by a suitable spreading operation. Preferably associated withthe washer is an inner bearing boss 36 which overlies and contacts with the bent-over end of the fuse strip when the ferrule is screwed down on the bushing.

Obviously, the loose attachment of the washer to the end of the cap permits the boss 36 to remain stationary in swiveling engagement with the ferrule as the latter is screwed home on the bushing. This vents injury by the boss to the fusestrip end which might otherwise be torn or ruptured during the screwing down of the ferrule were the washers forced to rotate with the ferrule.

Inassembled position the ferrules 12 are screwed down hard upon the end bushings 7 and 8, thus not only establishing good electrical contact with the bent-over ends of the fuse strips, but also firmly pressing the shutters 17 and 18 against the end diaphragms 13 and 14 of the bushings and positioning the skirt of the ferrule in engagemeut-with the reduced end ofthe bush- This orifice is largely, but

pre-

ing. This renders the closure of the fuse chamber complete, except for the restricted openings between the shutters and the diaphragms at the points at which the ends of the fuse strip pass out of the fuse chamber. On the blowing of the fuse, the gases emerge through this passage tothe expansion chamber 30, where they are cooled by expansion 'and reduced in pressure. From the expansion `chamber the Vgases are constrained to pass outward around the margins of the washers 32 into the channels 33, or the like, through which they flow, in cooling contact with the cap ends 31, to the vents 34. Their heat and pressure are now so reduced or dissipated that no danger attends their escape.

To remove the fuse strip it is merely necessary to. unscrew the ferrules 12, carrying the. washers 32, swing the shutters 17 and 18 outward to the position indicated in dotted lines in Fig. 3, whereupon the burnt fuse 4strip ends may be removed through the openings 19 in the bushing, a new fuse strip inserted therethrough, the shutters swung back to closure position and the ferrules again adjusted. It will be noted that there are no loose washers or parts apt to be lost or misplaced, the Shutters 17 and 18 being permanently -attached to the diaphragms 13 and 14, and the washers 32 Y being -permanently attached to the ferrules 12.

The provision of the exposed indicator 28 on the fuse renders inspection of the latter simple, and insures the use of a fuse strip of proper capacity for the casing. 'While it is intended that within a given range, fuses of diiierent capacity may be used with a single casing construction, the

. variation of the thickness of the fuse strips is not sufiicient to render the seal at the grooves 26, 27 ineffective. Were it4 attempted, however, to insert a fuse strip of greater capacity than that for which the cas- -ing is designed, its greater thickness would skilled in the art, and I do not limit my invention to the precise structure illustrated and above described.

I claim- Y 1. A cartridge fuse having a detachable end closure cap, and permanently secured therein in loose relation a gas-deilecting and heat-absorbing washer.

2. A cartridge fuse having a detachable los iis

izo

end cap, and permanently secured within the same in loose relation ak gas-deflecting and heat-absorbing washer affording a vent passage between the outer face of the washer and the inner` face ofthe end cap, said washer being of less diameter than the internal diameter of the cap.

5. In a cartridge fuse, a detachable `end cap, in combination with a washer carried thereby on its inner face, and a boss on the inner face of the washer for making contact with the end of a fuse strip.

6. In a cartridge fuse, a detachable screw cap, and-carried thereby a fuse contacting member freely swiveling in the cap.

7. A cartridge fuse having a substantially closed fuse chamber, and means for supporting in exposed (position at one end thereof the bent-over en of a fuse strip, in combination with a detachable end cap, and loosely carried thereby a contactfmember adapted to engage the end of the fuse strip.

8. A cartridge fuse having a substantially closed fuse chamber, and means for supporting in exposed position at one end thereof v the bent-over end of a fuse strip, in combina-fe `tion with a detachable fend cap, and freely,

carried thereby a venting contact member 'the latter and the cap.

adapted to engage the end of the fuse strip. 9. A cartridge fuse having a substantially closed fuse chamber, and means for supporting in exposed position at one end thereof,4 the bent-over end of a fuse strip, in combination with a detachable end cap, a washer carried thereby within the cap, and a boss on the inner face of said washer adapted to space the latter from the end 'of the fuse chamber to afford an expansion chamber for gases escaping from the fuse chamber on the blowing of the fuse.

10. A cartridgey fuse having a substany tially closed fuse chamber and means for supporting at one yend thereof the bentfover end of a. fuse strip, in lcombination witha detachable end cap, a washer carried by said cap and lying within the same, and a boss on the inner face of said washer to engage the bent-over end ofthe fusestrip and serving to space the washer from theend of the fuse chamber to yafford a gas expansion chamber, together with means affording a gas escape passage around the periphery of the washer and between -theouter face of 11. A cartridge fuse having a tubular casing of insulating material, a metallic I bushing secured at the end of the casing,

said bushing having an external screw thread and a reduced area at the outer end of said bushing beyond the screw thread, in combination with a detachable screw cap adapted to engage the threaded area of the bushing, and having a snug fit with the reduced end of the bushing to prevent the escape of kgas thereby to the threaded area.

In testimony whereof I have signed my name to this specification.

ARCHIBALD GRIEVE.

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