US1636182A - Fuse plug, screw type, with indicator - Google Patents

Description

July 19,1927.

- J. B. GLOWACKI FUSE PLUG, SCREW TYPE, WITH INDICATOR Original Filed Mayl5, 1922 :Patented July 19,1927.

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FUSE PLUGQSCBEW TYPE, WITH INDICATOR.

Applicatioh sued m 15, 19212, semi No. 560,916. Renewed December 8, i928.

This invention relates to that type of renewable fuses which are adapted to screw into a socket similar to a lamp socket and are known as fuse plugs.

yet which shall not be likely It is an object of this invention to provide such a fuse plug with an indicator which shall clearly and readily show which of a j collection of fuse plugs'has been blown.

It is a further object of this invention to provide a detachable mounting for a fuse strip of a type that may be easily and quickly inserted in a fuse plug and in which the fuse strip may be very readily renewed without" the need of any special tools. 7 It is a further object of this invention to provide a fuse lug of a type which shall afford an abundant outlet for the products of the explosion when the fuse is blown and i to set fire to the surroundings. I V I Y It is a further object of this invention to provide a tortuous and narrow passage which shall relieve the explosion but shall not permit the flame to emerge.

It is a further object of this invention to provide thetop of the fuse plug with an indicator which shall by its color or condition show when the fuse has been blown.

It is a further object of this invention to make a fuse plug of the type described which shall be simple and compact in structure and neat in appearance.

Other and further important objects of the invention will be apparent from the dis-' closures in the drawings and specification. The invention (in a preferred form) is illustrated on the drawings and hereinafter more fully described. On the drawings: Figure 1 is aside elevation plug.

Figure 2 is a central vertical section through the plug.

of the fuse Figure 3 is a bottom plan. view upon an enlargedscale of the fuse carrier.

Figure 4 is aside elevation of the fuse car I rier. v

Figure .5 is an edge view of the closure plate for the fuse carrier.

Figure 6 is an edge view of the fuse. Figure 7 is a top plan view of the fuse carrier with the fuse and .closure plate in position. I

Figure 8 is a bottom plan view of the head of the plug with the shell and spacing plate in place.

Figure 9 is a bottom pleted' plug.

1Ftiagure 10 is a section through the spacing p a a Figure 1L is a planview of the comsection upon an enlarged scale through the lower end ofthe fuse carrier.

Figure 12 is a section upon the line 12- -12 of Fig. 4..

Figure 13 is a-section upon an enlarged scale of the upper part of the plug in a plane at right angles to the section of 2, the indicator bein removed. i

As shown onthe rawings: The plug comprises a fuse carrier 1 and a head 2, bothm'adeofyinsulating material. The fuse carrier isscrewed into the interior of ascrew-threaded shell"? and the head 2 is screwed onto the exterior "of the same shell, the head being screwed onto; the. shell gure at one end and the carrier screwed into the shell at the other end. K

Thecarrier 1 is made of insulating mate r1al in the shape of a hollow cylinder havin euq a lower end wall 4 which is provided with a circular recess 5 preferably having a beveled edge. The central part of the recess 5 con-. tains a circular depression 6- in which is formed a rectangular depression 7, the core ners of which extend beyond the circumfer-- GDCO'OIET the depression 6; At'the center of the rectangle 7 the depression is crossed by a slot 8 which pierces the wall 4 of the container 1. The interior of the container is a straight cylindrical hollow except that near its upper end it' is provided with a shoulder 9 to afford a seat for a metallic closure plate 10. At two diametrically opposite points the cylindrical wall is cut away down to the level of the shoulder as.

is screw-threaded as shown at 16 to fit the screw thread of the shell 3; and the lower part of the carrier isknurled as shown at 17 to facilitate the screwing of the carrier into the shell.

The strip 18 of fusible metal is provided with narrowed places 19 to localize the heating. One end of the strip 18 is folded at a right angle as shown at 20 and. then folded through 180 degrees so that it projects in the opposite direction as shown at 21. The part beyond the last fold extends beyond the unfolded portion of the strip and is exanded into a circular-member as shown in igure 9 at 22. lVhen inserting the fuse into the fuse carrier the straight portion 18 is passed through the slot 8 so that the portion 20 comes to lie in one half of the rectangle 7, and the )ortion 22 fills the circular depression 6. he closure plate 10 is then inserted in place and the slot 23 therein receives the other end of the strip 18. This end is then bent flat against the outer face of the closure plate 10, asshown at 24 in Figure 13. The fuse carrier andits fuse are then ready to be screwed into the shell 3.

Before the shell receives the fuse carrier its spacing plate 25 is inserted in the shell. As shown most clearly in Figure 13, the shell consists of'a screw-threaded side wall, generally cylindrical in character, and an end 26. This end provided with a central opening 27 opposite the middle of the spacing plate 25, but not in contact therewith be-.

cause theplate 25 has an upstanding flange 28 which provides a distance between the surface of the plate and the surface of the end 26 of the shell. The other side of the plate has a raised middle portion as shown at 29 which contacts with the turned over end 24 of the fuse strip 18. The spacing plate 25 is provided with holes 30 which connect the space into which the hole 27 opens with the space 15 made by reducing the diameter of the fuse carrier 1. This space 15 is connected with the interior of the fuse carrier by orifices 32 shown most clearly in Figure 12.

The head 2 is traversed by a passage leading to the hole 27 and this passage is screwt-hreaded for the reception of an insulating tube 33 which is shown in section in Figure 2. The lower end of the tube is threaded to fit the threads in the passage 27. The screw-threaded portion is separated from the rest of the tube by a flange 34 which fits into a recess 35 in the top of the head 2. The upper end of the tube is closed by an end wall. In the illustration chosen this end wall is shown as dome-shaped, but this is not necessary. A little way below the end the tube has lateral openings 36 and just below the openings 36 is a shoulder so that the upper end of the tube is of slightly smaller diameter than the part just above the flange.

A cover 37, )referably of gelatine or other light and transparent material, is fitted over the tube 33. The lower end of this cover fits the tube 33 and abuts against the flange 34. The part of the cover above the shoulder is spaced away from the smaller part of the tube and so affords a space into which the openings 36 lead. At the upper end of the cover a small perforation is provided as shown at 38. A communication exists between the interior of the fuse carrier 1 and the outside atmosphere. This communication is through the holes 32 into the space 15, through the holes 30 into the upper part of the plate 25 through the hole 27 into the tube 33, and through the holes 36 into the interior of the cover 37; and finally throu h the hole 38 to the outside atmosphere. he cover 37 may of course be omitted and the same venting action attained.

In assembling the device, the plate 25 is first placed inside, of the shell 3 with the flange 28 against the end of the shell. A pin prick or other depression is then made in the side wall of the shell 3, as shown at 40, to retain the plate 25 in position. The closed end of the shell 3 and a portion of the threaded sides of the shell adjacent thereto are then coated with cement and screwed into the head 2. The fuse 18 is then inserted into the container 1 through the slot 8, as already explained. The closure plate 10 is assed over the other end of the fuse 18 wit the ears 12 entering the recesses 13 and the protruding end of the fuse 18 is bent over against the plate 10 as shown-in Figure 7. The fuse carrier 1 with the fuse therein is then screwed into the shell 3 and the end 18 of the fuse contactsv with the raised part 29 of the plate 25. The tube 33 is then screwed or otherwise permanently secured into the opening in the end of a base of the head 2 so that the flange 34 comes into the recess 35. The cover 37 is then placed over the tube 33' and the lower edge of the cover contacts with the flange 34. Preferably the cover is wet just before being laced on the tube so that it will adhere to t e tube around the lower edge of the cover.

The fuse plug is then read for. use. It is screwed into a suitable soc et. similar to a lamp socket. The screw threaded part of the socket contacts with the shell 3 and makes one terminal of the circuit. The central cont-act of the socket contacts with the end 22 and forms the other connection to the fuse strip 18. For this reason, the depression 5 i made no deeper than the height of the central projecting contact in a socket so that contact is always secured between the end 22 and this part of the socket. When the current is turned on it flows through the shell 3 to the plate 25, throu h the elevated' part 29; to the end 24 the fuse, through the fuse to'the end 22, and so to the other terminal in the socket.

When the current becomes excessive the fuse melts and if the excess is sudden and large the fuse may even vaporize suddenly enough to produce an explosion. The products ofthe explosion pass out of the interior of the container 1 through the holes 32 into the space 15. Emerging from the com paratively small holes 32 into the roomier space 15 checks the velocity of these products. They then pass through the holes 30 which emerge into the space above the plate 25. Here again the emerging'from a hole into a larger space, accompanied by. change of direction, checks the velocity of these products. The products then pass u the tube 33, sufier another change of direction to emerge through the hole 36, and finally come out into the interior of the cap 37. If there was butli'ttle force to the explosion the velocity of the products of the explosion will have largely disappeared by the time this travel is accomplished and they will emerge through the hole 38 in the form of a slow line of smoke. If however the velocity is greater there may be force enough to break or displace the; cap 37. Even when the cap is not broken or-displaced the fumes from the I explosion will discolor it so that the presence of the fumes is readily recognized.

Even with explosions of considerable vio-' lence the many changes of direction and the frequent emerging from hol'es into roomier spaces check the outflow so effectively that no actual flame reaches the outside of the plug.

When the failure of light in the house or other occurrence makes the user of the device aware that a fuse has blown and he goes to the fuse box toeinspect the same, the thin thread of smoke emerging through the hole 38 in the case of the fusg that has blown enables him to quickly ldcate said fuse; or if the observer arrives at the fuse box too late to see this he can observe which cap 37 is discolored ,or broken, or displaced, and

thus readily identify the fuse that. was blown. He then unscrews the fuse from the plug, unscrews'the fuse container from the cap 2, removes the remaining portions of the strip 18 and inserts a new strip in the way described, then screws the container back into the shell 3 and the plug back into the socket. The whole of this operation takes but a few seconds as compared. with the many minutes usually used to replace a fuse wire.

struction may be varied through a wide range without departing from the principles of this invention, and I therefore do not purpose limiting the patent granted otherwise than necessitated by the prior art.

I claim as m invention:

1. A screw-h secured in one end thereof, said plate having holes therethrough, a fuse container screwed in said shell, a fuse in said container,said container having holes communicating with the interior of said shell on one side of said plate, and a head screwed on,said shell, said ead having a passage therethrou h communicating with the other side of said late.

2. In 'a fuse plug, a hollow cylin er, a closure plate at one end of said cylinder, said plate having a slot therethrough, a wallintegral with said cylinder situated at the opposite end of said closure plate, said wall aving a central slot therethrough and a depression on the exterior immediately surrounding said slot, a fuse in said plug extending through said cylinder with one end projecting through said slot in said closure plate and the other end projectingthrough said slotin said wall, and a head on said fuse occupying said depression.

3. In -a 'fuse plug, a hollow cylinder, 9.

fusible element mounted in said cylinder, a'

shell on the outside of said cylinder, a head removably secured jon one end of said shell, a tortuous outlet from the interior of said cylinder to the outside 'of said head, and a transparent apertured cap positioned over .said outlet.

4. In a fuse lug, a hollow linden a screw-threaded s ell on the outsi e of said cyhnder to engage within a socket, a head screwed on one end of said shell, a dishedreaded shell, a dished plate.

plate secured in one end of said shell and having a plurality of holes therethrough, a closure late removably securedto one end of said cy lnder, said plate having a slot there through, a wall integral with said cylinder oppositely positione to said closure plate, said wall having a slot therethrough and a depression immediately surrounding the exterior of said last mentioned slot, a fuse extending through said last mentioned slot, the interior of said cylinderyand the slot in said closure plate, saidfuse being bent over after extending through said last mentioned slot and frictionally held between said closure.

plate and said dished plate, a head on said fuse occupying said depression, said cylinder having ap urality of holes therethrough, said head having ahole therethrough, a transparent apertured cap centrally positioned over said head comprising an insulating tube closed at one end, said tube being threaded .to fit said hole and having lateral openings,

J s a transparent cover for said tube. I am aware that numerous details of con- J OHN B. GLOWACKI.

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