US1600435A - Fuse plug - Google Patents

Description

Sgpt. 21, 1926.

H. L. STRONGSON FUSE PLUG Filed Nov. 6, 1922 IN VEN TOR nypo i ATTORNE Y Patented Sept. 21, 1926.

l UNITED STATES unman L. s'rnonosou, or BROOKLYN, NEW Yo n's s xonon "rofsritonoson Urn ITIES CORPORATION, or NEW YORK, N. Y., a conrom 'rron orjnnw you,"

rusn PLUG.

Application filed November 6, 1922. sena1'no.-599,21s.

I v This invention relates to fuse plugs and more particularly to improvements in renewableindicating fuse plugs, and consists in improvements over my patent application Serial Number 582,121 filed August 16,

Primarily the object of the present invention is to provide asimple fuse inexpensive to manufacture, which is positive in its indicating function, and which indicates a blown or burned fuse upon the rupture of the said fuse link caused either by short-circuiting or an over-load current; and an additional object is to improve indicating fuse plugs by ernploying a combined pressure indicator actuated by the heat and pressure liberated by the burned or exploded fuse link together with a means for spring pressing the-said indicator outwardly to visible position.

Though I have, as a mattercof course. certain objects and ends in view which are mainly similar to those of other inventors as expressed in the prior art, I provide a dif ferent structure and it is with my actually improved fuse plug structure embodying a rearrangement and re-organization of parts which enables me'to produce a reloadable indicating fuse plug which, in practice ac complishes and carriesout the purposes and 30 exoelsin function the performance of known fuse: plugs, and commercially functions to meet all requirements which are not met by other patented devices. 4 I

' v The accompanyingdrawings illustrate'an exemplary embodiment of my fuse plug serving to explain the principle ofthe invention which may be adapted to various modifiedstructures to better suit the needs of manufacturers'and users.

Figures 1, 2 and 3 illustrate, respectively,

top, side; and bottom projections of the fuse plug a a 4 ternal structure thereof.

moved from the reload indicating plunger placedin position and made ready tobe pressed down on the terminals prior to inserting the reloaied parts in the cover barrel or fuse'plug body. at

later described, and is provided with a cen- "Fig-ure 4 illustrates an enlarged ilongitudia nal section of the fuse plug showingthe in- Figured is a perspective view ofthe in} dicatingr'eload fuse plug with the cover re and closure cap together with a fuseribbon' 1 Figure 6. shows an enlarged v'iew of the reload cap and plungerremoved from'the'fuse plug body or cover with a new 'fuse. ribbon in position' I,

Referrin now more particularly to the drawings or a detailed explanation of an embodiment of my invention, there is shown a reload plug cap or barrel closure plug comprising a knurled grip 9 with stepped or reduced bosses or portions 10 and 11 which function as sealing shoulders to make a flame tight structure though permitting the clo-- sure cap 9 to be easily removed from the fuse plug body. This reload or closure cap is made with an internal bore or molded core 12 for the reception of the indicator as ter contact 13,'and a fuse terminal 14:; The fuse terminal 14 joins the contact screw 13, or the screw may be omitted inasmuch as the terminal 14 is exposed at the end of the fuse plug. The upper'end of'the fuse terminal 14 is preferably flexible or spring lil re and is adapted to flex inwardlya'g'ainst'the boss portion 1'0-when the fuse plug cover'is applied; and this" part 14 is preferably eI'Iibedded or molded in the cap, as"sho:wn,'to produce a substantial rigid constru'ctionl' The plug cap 9'11 'i's alsoprov'ided with another terminal preferably punched from sheet material consistingof a plate 15 an-" chored to the cap, and the plate has a close 1y spaced fuse terminal 16 and'out side con- I tact 17. The two parts 16 and 17"preferablyii possess springiness or, yieldability so: make effective electrical contactwith parts engaging them'gand the contacts 16 and'17 f are integral withtlie plate '15 'as*observed.; This member 15 is molded or straw-fastened tothe part 10; andthetwo'fus'e terminals 14" and 16 are preferably oppositely {disposed forthe convenient reception of the fus'eribbon ends as will "be-"described; An indicating 'plunger hasamine-mating head 19'withanintegrah res'surpisto' 20} and a sleeve "21. I The indicator-s1 sl'i'dably' confinedin the bore 12bit by any suitable-'mjeans'such "asby pin; 22" anchoredin the upper part of the' ca'p 9 with V its' end projecting'intoa groove E23 in""the sleeve 21 which holds th'e parts together ear-1; ing the. reloading operation while th'' capt" and indicator 19areoutofthefuseplug body cover to be described. A light coil spring 24 is confined in the plunger sleeve .21 with its lower end bearing against the bottom of the bore 12 thereby tending to force the indicator 19 upwardly. The indicator 19 is provided with a fuse receiving hole 25 below the piston through which a fuse ribbon is inserted as shown in Figure 5.

A threaded cover barrel or fuse plug body 28 is provided with a knurled hand grip 29 by which it is screwed into the receptacle. The upper end of the plug body 28 is provided with a hole or indicating orifice through which the indicator 19 projects when the fuse is blown or ruptured, and the lower end of the fuse plug body or cover barrel is open to receive the reloaded indicator and cap; and this body comprises a cylinder in which the piston 20 moves upwardly to expose the indicator. ternal threaded surface of the fuse plug body 28 is provided with a longitudinal groove 30 into which slides the outside contact 17 when the parts are assembled. lnternal grooves 31 and 32 are made in the plug body 28 for the sealed reception of the fuse terminals 1e and 16, the said larger groove 31 fitting over and sealing the fuse terminals 15 and 16, and the opposite groove 32 fitting over and sealing the other terminal 14.

The fuse plug is reloaded with, as for example, a standard type fuse link such as shown in the drawings, which usually possesses enlarged contact ends 34; and a centrally reduced fusing thread portion 35; and the fuse ribbon is inserted through the hole 25 while the plunger 19 and cap 9 are pressed together; and thereafter the two fuse ends 34 are folded down over the fuse terminals 14 and 16 such as is shown in Figures 4 and 6. The hole 25 in the indicator plunger acts as a centering means by which, in loadin the plug fuse, one may quickly perceive a bout when the center art of the fuse thread 35 is in position or folding down the ends 34. By gripping the fuse ends 34 onto the terminals between the thumb and finger, the indicating plunger is held downwardly as the fuse plug cover 28 is placed in position over the reloaded element, and the fuse is then ready for'use.

After the plug is assembled it is screwed into a fuse plug receptacle socket, the outside contact blade 17 yielding inwardly in contact with the metal shell of the receptacle thereby establishing positive contact; and the center contact 13 seats against the center receptacle contact into which the fuse plug is screw-inserted. The electric circuit is then completed through the plug by running from the side contact 17 through the fuse terminal 16, through the fuse and thence downwardly through the fuse terminal 14 to the center contact The ex-' When the fuse thread 35 burns or explodes due to a short-circuit in the line, the gases and heat liberated produce a powerful upward thrust under the piston 20 reacting against the upper face of the closure cap portion 11, and quickly projects the indicator 19 into exposed position. In a similar manner when the fuse ruptures under an overload current value, the pressure generated by the heat liberated is largely accentuated by the spring 24 causing the plunger to quickly rise through the head 29 of the fuse plug body producing a positive indication. The piston 20, when it shoots upwardly against the upper end of the cylinder, effects a sealed joint against the inner surface of the cover where the indicator head projects through thereby stifling the arc and flame and preventing a discharge of fire from the plug.

The indicator piston 20 seals the upper end of the fuseplug and the cap 911 seals the lower end thereof against escape of fire when the fuse melts, yet the piston and indicator head afford a ventin means in the nature of a tortuous passage by causing the fuse gas to escape around the circumference of the piston and inwardly toward the indicator and finally out of the plug body through the slight clearance afforded for the free movement of the indicator head 19.

It is to be noted that the piston 20 occu pies a position relatively central with respect to the parts 19 and 21 which extend therefrom; and in this arrangement there are accomplished several important func' tions with a single piece of structure. For exam 1e, the piston, so to speak, divides off the plug fuse into a lower portion containing the working parts and an upper portion affording space and volume for dissipating the heat and gases, for it is to be appreciated that, as the piston 20 moves upwardly in the cylinder, the volume or space under the piston in which the fuse burns is increased which allows a natural expansion of the fuse gas thereby more easily spending the force and energy'of the heat liberated by the burning fuse; and while this is not itself broadl new, it is novel in a simple renewable indieating fuse plug capable of quick reloading operation, for I have adapted this useful principle to my new improvements and reorganization of structural arrangements over the prior art. The lower stem 21 projects from the piston and is slidably confined the removable closure cap thereby holding together the plunger and cap as a unit 9-19 when the body 28 is removed for reload purposes which afi'ords convenicLce and eliminates the replacing of loose parts back into the threaded body 28, for it is to be appreciated, as in Figure 5. the devi e only separ a tes lCIIIiZO two parts when reloading is to be cnecte needed to holdthe cap 9 in the cover body because the receptacle into which the plug fuse is screw inserted holds the cap in: place against the most forceful burning of a fuse;

and in the same manner no metal shell is necessary for contact purposes, for the flat broad blade 17 adequately provides for this requirement. Furthermore my contact and terminal arrangements, whereby the contact 17 and terminals 14 and 16 register in grooves of the cover, rigidly holds the cover and reload unit in fixed relation to prevent the cover 28 from turning on the cap 9. In other devices it has been necessary to employ screw shells for this purpose which handicaps reload operations.

The construction of my plug fuse accommodates a fuse ribbon of substantial length and enables the fusible portion to be positioned well up into the body of the device thus segre ating the metal fuse terminals from the f using part of the fuse element. Furthermore, I do not in any way permit the spring 24, which assists the indicator in projecting itself into view, to come in contact withthe, renewable fuse ribbon. for insulating material completely encloses the spring v t I v The flat ends 34 of a conventional fuse link, which myplug fuse receives, very read ily lap down against the terminals, for it is to be appreciated that these fuse ends dc not have to be hooked over or folded under terminal parts. While it may be suggested that renewable flat fuse ends'may be held in place by a metal screw shell or by a metal ring, being extra parts, I cause the plug body itself to perform this function. I explain this feature of my structure because of the extreme difliculty one encounters in trying to fasten a soft delicate fuse link over hooks, prongs or even under a brass screw shell as it shown in\ some patents.

Spring pressed plungers and indicators are known in the. art and largely suggested as a means for quickly separating the burning fuse ends to quickly extinguish the arc;

and in some instances a plunger may be employed to jump between the burning fuse ends to, act as a barrier. In my invention I have other objects in View in the use of my spring 24 for indeed my plug fuse need not have its terminals-separated,,nor its fuse ends jerked apart, for such action sometimes causes a premature rupture oflthe. link and the unnecessary interruptionof the supplyof current. The terminals ofthis fuseplug are sealedin between two pieces of insulation and are never. damaged by the 'arcing of the, fuse. There is not one single piece of metal,

nor fixtures, nora spring part,or-other sub stance, within the fuse burning chamber ex cept the fuse link, andconsequently no dan ger exists as to the'drawing'out or -prolonga-' '70 tion of the fuse burning period.

This fuse plug is easy to reload, possesses few parts, and enables one to quickly locate a blown fuse plug among many others, even in dark places.

What I claim is 1. A fuse plug comprising, an externally threaded fuse plug body provided with one end open and an indicatin orifice in the other end, a closure cap i emovably closing the open end of the body, an indicator mounted on the closure cap and projecting into the indicating orifice and adapted to move relatively to said cap parallel to the axis of the fuse plug body and cap, means positively holding the indicator on the cap so that the cap and indicator are removed and replaced as a unit from the body, fuse terminals to engage a renewable fuse link, and plug contacts connecting with the fuse terminals.

2. In fuse plug improvements, a fuse plug body externally screw-threaded and open at one end, a removable closure cap provided with a longitudinal bore and adapted to seal the open end of the plug body, an indicator projectable from the fuse plug body and slidably confined in the bore of the cap, a. spring to exert an'outward thrust on the indicator, fuse terminal and plug contacts, and fuse link reception means to carry aflfuse in a way to engage and hold inwardly the indicator.

ing an open-ended fuse plug b0 y, a removable closure cap to seal up the body, an in-, dicatorrnovably carried on the cap and removable from the body with the cap, a spring 3. Improvements in fuse plu s, compris-Y interposed between the indicator and cap to exert force against the indicator, fuse terminals, a fuse link reception means to carry a fuse engaging the indicator to hold 1t down on the closure cap, and fuse plug contacts connecting with the terminals.

4. Improvements infuse plugs comprisng a threaded plug body knurled on one end for a hand-grip and open at the other end, a.

removable cap adapted to close the plug and provided with a central bore,'an indicatonslidably confined in the cap bore, a spring in the cap bore exerting an indicating force against the indicator, means on the'indicator for receiving a reload fuse link, fuse terminals adapted to engage the fuse link ends and hold the indicator down when assembled, and fuse plug contacts connecting with the fuse terminals.

5. Improvements in fuse plugs comprising a threaded body with one end open and the other end having a restricted indicating opening, a removable closure cap to seal the bodv and close it at one end, an indicator confined in the restricted body opening to close the other end of the body, a plunger made on the indicator and extending into the cap and slidably carried thereby and removable with the cap from the threaded body for reloading purposes, fuse link holding means related with the plunger and the cap which receives a fuse link that holds the indicator in compressed relation upon the cap, fuse terminals to engage the link, and plug contacts connecting with the fuse terminals,

6. Improvements in fuse plugs comprising a plug body having an end thereof made open, a removable closure cap to seal the open end of the body, an indicator projectable from the plug body, means for securing the indicator and cap together in a movable relation to prevent their separation when removed from the body for reload purposes, fuse terminals to engage the link, and fuse plug contacts connecting with the fuse terminals.

7 Improvements in fuse plugs comprising a body open at one end, a removable cap to seal the open end of the body, an indicator movably carried on the removable cap, a spring interposed between the cap and indicator to exert an indicating force, fuse-terminals carried on the removable cap which engage a fuse link to hold down the indicator, and fuse plug contacts which connect with the fuse terminals.

8. Improvements in fuse plugs comprising a body open at one end, a removable cap to seal the open end of the body, an indicator movably carried on the removable cap, a spring interposed between the cap and indicator to exert an indicating force, fuse terminals carried on the removable cap which engage a fuse link to hold down the indicator, a center fuse plug contact on the cap connecting with one of the aforesaid fuse terminals, and a side fuse plug contact integral with the other aforesaid fuse termi nal and extending outwardly from the sealed body and cap.

9. Improvements in fuse plugs comprising a plug body open at each end and externally screw threaded, an indicator slidably retained in one open end to close that end of the body, a removably reloadable closure cap adapted to seal the outer end and provided with a longitudinal bore, a sleeve extending from the indicator into the bore of the cap of to remove it from the opening in the body, an indicating plunger movably carried by the cap, a spring to urge the indicator away from the cap, fuse link receiving means to hold the indicator down when reloaded, fuse terminals forming part of the means, and fuse plugs contacts connecting with the terminals.

' 11. Improvements in fuse plugs comprismg a plug body with an indicating opening and internal cylinder bore and external screw threads and being open at one end and having a knurled hand portion, a closure cap knurled for the convenient gripping thereof to remove it from the opening in the body, an indicating plunger movably carried by the cap, a spring to urge the indicator away from the cap, fuse link receiving means to hold the indicator down when reloaded, fuse terminals forming part of the means, fuse plug contacts connecting with the terminals, and a piston carried by the indicator reciprocable in the aforesaid cylinder to accentuate the spring urged indicator and to seal the indicating opening.

12, Improvements in fuse plugs comprismg a fuse plug body made with an internal cylindrical bore and being open at one end, a. removable reloadable closure cap fitted into the open end of the body, a piston slidably confined in the bore, an indicator carried by the piston and projectable from the plug body, a part integral with the piston and projecting down into the reloadable closure cap, means for movably securing the said part onto the cap to prevent separation thereof, reload fuse terminals and fuse plug contacts carried on the cap.

13. In fuse plug improvements, a hollow plug body with one end open and an indicating orifice in the other end, a removable reload closure cap fitted in the open end of the body, an indicating plunger carried on the inner end of the closure cap being slidably related therewith and fixed against detachment from said cap, a resilient means for urging the plunger to an indicating position,

fuse terminals and plug contacts carried on the cap.

14. In plug fuse improvements, a hollow body for insertion into a receptacle base and to contain plug fuse parts, said body being open on one end and having an indicating orifice at the other end, a removable reloar closure cap designed to close the open end of the body, an indicating plunger movable in the body with one end thereof slidably rctained against detachment withinthe closure cap and the other plunger end shdably con- 1 fined in the indicating orifice, fuse terminals and plug contacts carried on the cap.

15. In plug fuse improvements, a hollow body for insertion into a receptacle base and to contain plug fuse parts, said body be ng open on one end and having an indicating orifice at the other end, a removable reload closure cap designed to close the open end of the body, an indicating plunger movable in the bodywith one end thereof s'lidably' retained against detachment within the closure cap and the other plunger end slid' of the body, an indicating plunger movable in the body with one end thereof slidably retained against detachment within the closure cap and. the other plunger end slidably ably confined in theindicating orifice, a'piston carried in the hollow body and designed to produce an upward thrust upon the indicator when a fuse burns, and fuse terminals and plug contacts carried on the cap.

17. In lug fuse improvements, a hollow body for msertion into a receptacle base and to contain plug fuse. parts, said bod being open on one end and having an in icatin orifice at the other end, a removable reloa closure ca designed to close the open end of the bot? an indicating plunger movable in the bo y with one end thereof slidably retained against detachment within the closure cap and the other plunger end slidably confined in the indicating orifice, a piston carried by the indicator, said indicator provided with a fuse receiving holeadj acent the piston, and fuse terminals and plug contacts carried on the cap. a

18. In plug fuse improvements, a hollow body for lnsertion into a receptacle base and to contain plug fuse parts, said bod being open on one end and having an in icating orifice at the other end, a removable reload closure cap designed to close the open end of the bod an indicating plunger movable in the ho y with one end thereof slidably retained against detachment within the closure cap and the other plunger end slidably confined in the indicating orifice, a piston carried in the hollow body and designed to produce an upward thrust upon the indicator when a fuse burns, and fuse terminals and plug contacts carried on said cap, and a spring to accentuate the upward thrust of the piston to urge the plunger to indicating position.

19. A plug fuse comprising a body made of insulation with one end open and threaded to screw into a fuse receptacle base, a knurled hand grip on one end of the body, a closure cap designed to seal the open body end and removable for inserting a renew fuse, an indicating plunger slidably carried upon carri thej c p and fixedagainst eas ment "was,

lug contacts 7 the; ca", fuse terminals and I on' the cap, and a'knur ed grip made on the cap .by which'the plug fuse may be,

gripped'by the two aforesaid knurledparts and opened, forf'reloading operation. I 20. Aplug fuse comprising a body made of insulation with one, end open and threaded to screw into a fuse receptacle base, a

knurled hand grip on one end of the body, a. closure cap designed to seal the open body end and removable for inserting a renew fuse, an indicating plunger slidably carried upon the cap and fixed against detach- 'ment with the cap, a spring urging outwardly on the indicator, fuse terminals and plug contacts carried on the cap, and a knurled grip made on thecap by which the plug fuse is gripped for separation thereof.

21. A plu fuse comprising an externally threaded ody open at one end and having a cylindrical bore, a removable reloadab e cap fitting into the open end of the body, said cap made with a bore, an indicator plunger extending through the cylindrical ore of the body, a tubular stem made on the lower end of the plunger and slidably mounted in thebore of the cap, a spring confined in the cap bore and tubular stem to urge outwardly on the indicator, fuseterminals and lug contacts carried on the ca 22. AP u fuse comprising an externally threaded y open at one end and having a cylindrical bore, a removable reloadable cap fitting into the open end of the body, said cap made.with, a bore, an indicator lunger extending through the cylindrical ore of the body, a tubular stem made on the lower end of the plunger and slidably mounted in the bore of the cap, a sprin confined in the cap more to urge outwar y on the indicator, a iston carried b the plunger and reciproca le in the cylind er bore, and fuse terminals and plug contacts carried on the cap.

23. A plu fuse comprising an externally threaded b y open at one end'and having a cylindrical bore, a removable reloadable cap fitting into the open end of the body, said cap made with a bore," an indicator plunger extending through the cylindrical bore of the body, a tubular stem made on the lower end of the plunger and slidably mounted in the bore of the cap,'a spring confined in the cap bore to urge outwardly on the indicator, a piston carried b the lunger and reciprocable in the cy inder ore, andfuse terminals and plug contacts carried on the cap.

24. A plug fuse comprising a threaded bod with inside cylindrical bore, said'body ma e open on one end and a groove formed through the threads of said body, a ca to seal the open plug end, a side contact b ade the aforesaid groove, a fuse terminal integral with the contact blade and sealed between the body and cap, another fuse terminal located substantially opposite to the first named fuse terminal and similarly sealed, a center contact on the cap making connection with the last named fuse terminal, an indicating plunger slidably carried by the cap, and means related with the plunger to receive a renew fuse link engaging and holding down on the indicator.

25. A plug fuse comprising a threaded body with inside cylindrical bore, said body made open on one end and a groove formed through the threads of said body, a cap to seal the open plug end, a side contact blade carried by the cap and adapted to slide into the aforesaid groove, a fuse terminal inte gral with the contact blade and sealed between the body and cap, another fuse terminal located substantially opposite to the first named fuse terminal and similarly sealed, a center contact on the cap making connection with the last named fuse terminal, an indicating plunger slidably carried by the cap,

means related with the plunger to receive a renew fuse link engaging and holding down on the indicator, and a spring urging outwardly on the indicator.

26. A plug fuse comprising a threaded body with inside cylindrical bore, said body made open on one end and a groove formed through the threads of said body, a cap to seal the open plug end, a side contact blade carried by the cap and adapted to slide into the aforesaid groove, a fuse terminal integral with the contact blade and sealed between the body and cap, another fuse terminal located substantially opposite to the first named fuse terminal and similarly sealed, a center contact on the cap making connection with the last named fuse terminal, an indicating plunger slidably carried by the cap, means related with the plunger to receive a renew fuse link engaging and holding down on the indicator, a spring urging outwardly on the indicator, and a piston carried by the indicator.

In testimony whereof I affix my signature this 4th day of Nov., 1922; in the county of New York, city of New York, and State of New York.

HERMAN L. STRONGSON.

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