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Publication numberUS2220058 A
Publication typeGrant
Publication dateOct 29, 1940
Filing dateMay 6, 1937
Priority dateMay 6, 1937
Publication numberUS 2220058 A, US 2220058A, US-A-2220058, US2220058 A, US2220058A
InventorsKlein Franklin S
Original AssigneeKlein Franklin S
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electric fuse
US 2220058 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

Oct. 29, 1940. 5, KLElN 2,220,058

ELEGTRI C FUSE Filed May 6, 1937 mmvron Patented Oct. 29, 1940 UNITED STATES PATENT OFFICE 13Chims.

This invention relates to fuses for the protection of electric wiring andapparatus, and relates particularly to enclosed fuses and fuse links. The object is to provide an enclosed fuse by an economical combination and arrangement of convenient and improved parts having particularly well secured electrical connections of the fusible link, said parts having an economical tortuous vent for a fuse cartridge, and having means for interlocking the parts of a fuse against unintentional loosening; and either or all of the aforesaid in an irreducible number of parts.

Fuses of the renewable cartridge type, generally include from five to fifteen separable parts plus the fuse link to arrange in proper alignment, when renewing a fuse link. This improved fuse includes only three separable parts plus the fuse link.

The type of contact used in many renewable fuses, is such that one can only assume there is a good connection with the fuse link, and that a good connection will remain so. In this improved fuse there is an unusually positive connection between the fuse link and the terminals of the fuse case, which is obvious as the fuse case and the fuse link are. assembled, and means are provided to interlock the assembled fuse for safekeeping, other improvements also are disclosed, all with the object of providing a more satisfactory enclosed fuse, which is attained as described and as illustrated in the. accompanying drawing, where,

Fig. 1 is a view of an improved fuse partly sec- F tional.

Fig. 2 is another view of the fuse shown at Fig. 1, but without the fuse case terminals, showing one terminal of the fuse link disconnected, and the channels to vent the fuse combustion chamber.

Fig. 3 is a view of an improved fuse link.

Fig. 4 is an enlarged view of an improvedfuse for small fuse links, this case is broken in two parts to show opposite sides of the ends of the case, at one end is the disconnected terminal of a small fuse link which was smooth before being connected.

Referring in detail to the accompanying drawing, the number N indicates a nonconducting tubular casing composed of vulcanized fiber, number l2 indicates a removable fuse link enclosed in the casing ll, tubular metal ferrules I3 and I! are riveted H or otherwise fixed on the ends of the casing II which including ferrules is fully clear throughout, the ferrules l3 each have an external screw thread I! near that edge of the ferrule which is on the casing, and the remainder of each ferrule I3 toward the outer edge has the shape of a cone frustum I! or is conical in shape II, the ferrules it each have a longitudinally extending depressed space, chase, or path, formed by reducing the screw thread It, which I hereinafter term a groove I1 in the external surface of the ferrule, interrupting the screw thread l6, and the groove I1 continues on and into the case Ii for a very short distance. This groove serves to hold the fuse link against rotary displacement from abrasively established electrical connections.

Tubular metal caps I8 and ll comprise the terminals of the fuse case ll, each cap having a conical formation It on the inside walls toward the closed part of the cap it, this conical formation I! corresponds to the conical formation II of the ferrules l3, and the remainder of the inside walls toward the opening of each cap it is occupied by an internal screw thread 20 having blunt edges 2| to obviate the destructive cutting of sharp edges, because the threads 20 must make a strong abrasive contact with the terminals of a fuse link. The caps 18 each have a rectangular indentation 22 in the edge of the rim. It is to be understood that the external contact surface for the caps I0 is not to be limited to any particular type of fuse connection in a cutout block or fuse panel, for example, at Fig. 1,

' blade contacts are shown at 25, and at Fig. 3, the

contact surface is of the ferrule type.

It is to be noted that this fuse case consists of only three parts, each part substantial and rigid throughout, and the tubular casing fully clear throughout.

A vent for heat and expanding gas is formed in each end of the fuse case H, by parallel longitudinally extending open grooves or channels 23 and 24, in the external screw thread l5, and each'channel crosses all but one or two turns of the screw thread, each channel having one end open and one end blocked by unchanneled turns of the screw thread, the channel 23 having one end opening in the combustion chamber of the fuse case, the channel 24 having one end open to the outside of the fuse case and a plurality of such channels would alternate in this manner. Each cap is has a blunt edged internal screw v thread 20 which incompletely nlls the hollows between turns of the screw thread i5, therefore, when a cap I 8 is in place on the end of the case II, the channels 2! and 24 are covered and connected by lateral channels formed by the engagement of incomplete screw threads, and gas can escape through a tortuous network of indirect connecting channels.-

In Fig. 1, one of the above mentioned lateral channels is indicated by the number 2|, and it is to be noted that there are four of those channels in a row, and the diameter of each lateral channel is such as to restrict the passage of flame, yet

the aggregate oflateral passage for gas is about equal to the passage for gas through either of the relatively larger longitudinal passages 23 or 24.

This arrangement permits expanding gas to be vented copiously, thereby materially promoting the extinguishment of an arc when the fuse blows,

5 by promptly dispersing the metallic vapor through which an arc is maintained.

It should be recalled that an object of this invention is a particularly well secured electrical connection of the fuse link, and notice that the same is attained by electrically connecting each electrical terminal of the link by a gripping contact with said internal thread of the caps I8 and by again gripping each terminal between the corresponding conical surfaces I6 and I9. Either of these contacts are good electrical connections, but. by using both of these means for contact, a particularly eflicient electrical connection of the link is secured, the importance of which is scarcely to be belittled; and furthermore, while it is desired to prevent the use of fuse links having a capacity which is excessive for the cartridge,

it is harmless and frequently expedient to use links having a lower capacity and relatively thin electrical terminals which cannot be properly 28 gripped by the internal threads of the-caps I8,

but which will be properly gripped by the corresponding conical surfaces I6 and I9 while the grooves at I1 hold such thin terminals in position.

At Figs. 1 and 2, the caps I8 have the common 80 knife blade type of contact, but in this improved fuse the blade 25 and the terminal cap I8 are inseparable or made in one piece.

The fuse link I2 has the more fusible portion in the middle, and the terminals '26 and 26 which 38 are the electrical terminals of the link, being of insumcient pliability, are each provided with a multiple of parallel ridges and hollows 21 forming the segment 21 of a screw thread, these segments do not precisely correspond to a, screw thread and when engaged as such, will be slightly deformed by abrasion in the making of a good electrical connection, each terminal of the fuse link I2 has a supplemental portion 28 at the very end, and each portion bears marks 29 identifying 45 the electrical capacity of the fuse link. The terminals 26 .are relatively flat yet slightly curved to suit the curved form of the terminal caps I8 and the ferrules I3, and it is to be noted that these improved fuse links are essentially of extra 60 length.

Fuse links of each electrical capacity, will have terminals precisely corresponding in proportions to the groove I! in appropriate fuse cases when the caps I8 are in place, to prevent overfusing 55 exceptwith much difficulty, it is to be noted that this' arrangement makes it impractical to use the groove I! for venting gas, which is not desirable in that it would foul the electrical contacts, hence the vents herein described, but in every 00 instance the fuse link terminals will be proportioned for adequate electrical contacts, and for restricting the fusibility of the link to the combustion chamber, as illustrated.

To install the fuse link I2 in the fuse case II,

65 the straight fuse link is inserted inthe casing and each terminal 26 bent like a hook, to engage the groove I! in each end of the fuse casing, and

' that portion of each terminal which is like the segment 21 of ascrew thread, is held in posi- 70 tion to complete the external screw thread I5, where said screw thread is interrupted by the groove l1, then the caps I6 and I8 are screwed on both the fuse link terminals and the ferrules I3 and I3 of the fuse casing, thereupon 75 the internal screw thread of each terminal cap engages the corresponding ridges and hollows of each segment 21, thereby gripping the fuse terminals, and a portion 3| of each fuse terminal 26 is again gripped by,the conical surface I6 of each ferrule I3 with the cooperating conical sur- 5 face I9 of each cap I8, thereby abrasively establishing an exceptionally positive electrical connection of the link. In renewing these fuses, no

the case II and back against the external side of each caps, engaging each indentation 22 and revealing the marks 29 and 29 which identify the enclosed fuse link, thereby locking the assem- 20 bled fuse against unintentional loosening.

It is to be noted that in each cap I8, the indentation 22 is located for aligning and locking terminal blades in proper position.

It should be noted that the groove II at each 25 end of the fuse case, is on an opposite side of the case II, and the fuse terminals 26 are formed accordingly, therefore the fuse link I2 must take a diagonal position in the fuse case with the most fusible portion in the center of the com- 30 bustion chamber.

i The renewable fuse shown in Fig. 4, is a modification of the fuse at Fig. 1, and Fig. 2, and is intended for fuses of small capacity, small flat fuse links are composed of soft pliable material, 8 therefore in some of the new fuse links, the screw thread segment 21 is omitted, but the fuse terminal 26 will have the essential length, curved surface and supplemental portion 28, and an excellent contact is made with the terminals of 40 the fuse case by the blunt internal screw thread 20 of each cap I8 impressing and engaging correlative ridges and hollows in the normally smooth and pliable fuse link terminals, as the cap I8 is screwed on both the soft fuse terminal and the ferrule I3 on each end of the fuse case, and to make this grip better, the groove I! at each end of the fuse case II, at Fig. 4, is formed by having reduced screw threads as at 32 in the groove II, thereby providing a serrated bottom in the groove, which cooperates with blunt internal screw thread 20 in deforming and gripping the fuse link terminals 26.

This improved fuse provides, in three simple parts, simple connections, automatically scraped clean, electrically positive, and'eifectively locked.

The fuse links are renewed easily and with confidence. The fuses employing blade contacts are rigid in comparison with prior'fuses. The com- 'bustion chamber is easy to clean. The contacts 0 Y 1. A renewable cartridge fuse comprising, in

combination, a tubular casing having threaded ends and shallow fuse receiving channels extending across the threads, a threaded metal cap on each threaded end, and, extending through [5 the tubular casing, a. fuse link the ends of which constitute electrical terminals and are secured in said shallow channels by being gripped between the threaded faces of the threaded ends of the tubular casing and the threaded faces of the metal caps to provide electrical contact between the caps and the fuse link.

2. A renewable cartridge fuse consisting of a tubular casing, a fuse link having a central fusible portion extending diagonally longitudinally through the tubular casing to position the central fusible portion substantially at the center of the casing and having its end portions hooked over the casing ends, shallow longitudinal channels being formed on the outer surfaces of the tubular casing in which channels the end portions of the fusible link fit closely, and end caps for the tubular casing constituting electrical terminals and gripping the fuse ends in said channels between the outside surface of the sidewall of the tube and the inside surfaces of the sidewall of the end caps to form electrical contact with the fuse ends.

3. A renewable cartridge fuse, as defined in claim 1,. wherein one extreme end of the fuse link extends beyond the end cap and is exposed to view whereby a fuse designation on the end of the fuse link is-exposed to view;

4. In a renewable cartridge fuse having, in combination, a tubular casing with an externally screw-threaded ferrule on each end, two tubular metal members each having an internal thread to. engage said ferrules, and through the casing a fuse link. each end portion thereof being an electrical terminal thereof; means to electrically connect said terminals, comprising, a multiple of transverse ridges formed on said terminals to substantially correspond with said external threads of the ferrules, said ferrules having a longitudinal groove provided in each ferrule by reducing said external threads of the ferrules sufiiciently to contain said ridged terminals of the link hooked therein in complementary relation with the threads, and said metal members screwed on the ferrules thereby forming a gripping connection with said terminals of the link.

5. In a renewable cartridge fuse of the character described having, in combination, a tubular casing which includes two externally threaded ferrules each fixed to an end of the casing, two tubular metal closure caps each having an interna1 screw thread to engage the ferrules, and a fuse lin keach end portion thereof being an elec-- trical *I'er minal thereof; means to electrically connect said link, comprising said caps and an internal conical surface formed-on the inside wall of each cap adjacent to the internal threadthereof, said ferrules and an external conical surface formed on the outside of each ferrule to correspond to said conical surface oftthe caps, and each of said ferrules alsoprovided with a longitudinal groove by reducing said external screw thread sumciently to contain a terminal of said link hooked against said external conical surface and into said groove in combination with said caps, each cap closing an end of the casing, and gripping a portion of a terminal of the link between said corresponding conical surfaces, a portion of each terminal being also tripp d in the groove by the internal screw threads of said p 6. In a renewable cartridge fuse having, in combination, a tubularca'singwith an externally threaded ferrule on each end, two tubular metal members each havingan internal screw thread to engage the ferrules, and through the casing a fuse link each end portion thereof being an electrical terminal; means to electrically connect said fuse link, comprising, said metal member. and blunt edges formed on the internal screw threads thereof, said ferrules and a groove pro vided longitudinally in each ferrule by reducing the external threads thereof sufficiently to form serrations corresponding with the threads, and

space to contain said terminals of the link hooked therein incombiriation with said tubular members screwed on said ferrules, said blunt edged threads of the members thereby contributing to said space at the groove for the terminals and also deforming and gripping said terminals against said serrations and in complementary relation to the threads;

7. In a renewable cartridge fuse having, in combination, a tubular casing, two externally screw threaded ferrules each fixed to an end of the casing, two tubular metal members each having an internal screw thread to engage the ferrules, and through the casing a fuse link each end portion thereof being an electrical terminal thereof; means to electrically connect said link, comprising, said tubular members and a conical formation provided on the internal side wall ad- Jacent to and tapering from the internal thread, also blunt edges formed on said internal threads, said ferrules and a cone frustum formed externally on each ferrule to correspond with said conical formations of the tubular members, and each ferrule also provided with a longitudinal groove by reducing said external thread sufficiently to form serrations corresponding therewith and space to contain said terminal of the link when hooked against said frustum and into said grooves with said tubular members screwed on said ferrules, whereby portions of said terminals of the link are gripped between said frustums and said conical formations with said grooves holding the terminals in position. and said blunt edged threads contribute to said grooves and space for said terminals, and also deform and grip said terminals on said serrations in complementary relation with said threads.

8. In a renewable cartridge fuse having, in combination, a tubular casing which includes two externally screw threaded ferrules each fixed to an end of the casing, two tubular metal members having internal screw threads to engage the ferrules, and through the casing a fuse link each end portion thereof being an electrical terminal thereof; means provided in said elements to elecmeans to interlock said elements when assembled, and means to vent said casing when the I fuse link blows, said means comprising, said tubular members and blunt edges provided on the internal threads thereof, also an indentation provided in the rim of each tubular member, said ferrules and parallel channels formed longitudinally in each ferrule by reducing the external threads, one of said channels having an and open to the interior of said casing and the opposite end blocked, another of said channels having an end open to the exterior and the opposite end blocked, the hollows between said external threads forming lateral channels connecting said parallel channels, and each of said ferrules also provided with a longitudinal groove by reducing the external thread thereof sufilciently to form serrations and space to substantially contain said of the link hooked throughout said sroovewith said tubular members screwed on said ferrules, thereby, said blunt edged threads contribute. to said space in the groove for the, terminals and also deform and grip said terminals against said serrations and in complementary relation to said threads, said indentation in each tubular member engages with a bent up end of said terminal to interlock all, said tubular members also complete the formation of said channels into a tortuous passage to vent gas, which includes a multiple of lateral gas passages of flame restricting diameter formed by said blunt edged threads incompletely filling said hollows of the external screw threads, connecting the longitudinal channels.

9. In a renewable cartridge fuse having, in combination, a fuse link each end portion thereof being an electrical terminal, a casing consisting of a tube having two externally screw threaded ferrules each fixed toan end of the tube, and'two tubular metal closure caps each having an internal screw thread to engage the ferrules;

means to electrically connect said terminals of I the link, alsomeans to interlock said elements when assembled, and means to vent expanding gas, comprising, said terminals anda multiple of transverse ridges formed on a portion of each terminal to substantially correspond with said threads of the ferrules, said caps and blunt edges provided on said internal screw thread of each cap, also an'internal conical surface formed on the inside wall at the closed end of each cap, and anindentation provided in the rim of each cap, said ferrules and an external conical surface provided on the end of each ferrule to correspond to said conical surface in the caps, also parallel vent channels formed longitudinally in each ferrule by reducing the external threads, one of said channels having an end open to the interior of the .casing and the opposite end blocked, another of said external threads forming lateral channels connecting said parallel channels, and each ferrule also provided with a longitudinal groove formed by reducing said external thread sufficiently to form serrations which correspond with the threads, and space to contain a terminal of said link hooked against said external conical surface and throughout said groove with said caps screwed on the ferrules, thereby; said caps close the casing; and electrically connect said terminals by gripping portions thereof between said corresponding conical surfaces, with said blunt'edged threads of the caps, which also contribute to said space in the grooves for the ridged portion of said terminal, also gripping said ridged portions of the terminals against said serrations and in complementary relation to said threads; said caps also form said channels into a tortuous vent passage for gas, which includes a multiple of lateral passages of flame restricting diameter formed by said blunt edged threads incompletely filling the hollows between said threads of the ferrules; and an end portion of each terminal of the link bent up from the groove engages said indentations of the caps to interlock all.

10..In a renewable cartridge fuse having, in combination, a fuse link, a casing therefore provided with an opening and screw threads adjacent the opening to engage a closure member for the opening, a closure member for the opening having screw threads to engage the threads of the casing, and means to promptly vent expanded gas from said casing when a fuse therein blows; said means comprising, one of said parts and blunt edges provided on the screw threads thereof, the other of said parts and parallel channels formed longitudinally and across the screw threads thereof, one of said channels having'an end open to the interior of said casing and the opposite end'blocked, another of said channels having an end open to the exterior of said casing and the.

opposite end blocked, said parts screwed together thereby forming a multiple of lateral gas passages of flame restricting diameter, by said blunt edged threads incompletely filling the hollows between the cooperating threads, said lateral passages being preceded by a relatively larger passage from the interior of said casing and succeeded by another relatively larger passage to the exterior, whereby expanding gas may be "copiously vented and are conducting vapor promptly dispersed when the fuse blows.

11. In a renewable cartridge fuse having, in combination, a tubular casing, two externally screw threaded metal ferrules each attached to an end of the casing, and two tubular metal terminal members each having an internal screw thread to engage said ferrules; means to promptly vent expanded gas from the casing without the exit of fiame when said link blows, comprising,

said tubular members and blunt edges formed on the internal screw threads thereof, said ferrules and parallel channels formed longitudinally in each ferrule oy reducing the external screw threads thereof, one of said channels having an end open to the interior of said casing and the opposite end blocked, another of said channels having an end open to the exterior of the casing and the opposite endblocked, the hollows between the external threads of the ferrules forming lateral channels connecting said longitudinal channels, and said tubular members screwed on said ferrules, thereby covering all channels and forming a passage for promptly venting gas, part of the passage including a multiple of gas passages of flame restricting diameter formed by said blunt edged internal threads incompletely filling the hollows between said external threads of the ferrules.

12. In a renewable cartridge fuse having, *in combination, a fusible element with an end portion, a casing for the fusible element, the casing being provided with means to rotatably engage a terminal member, a terminal member adapted to rotatably engage said casing, one of said parts of the casing being provided'with means to expose said end portion of the fusible element on the exteriorof the cartridge, and, an indentation provided in the cooperating part, to engage said end portion of the fusible element and thereby interlock said elements.

13. In a renewable cartridge fuse having, in combination, a nonconducting casing having at each end an externally screw threaded ferrule, each of said ferrule provided .with longitudinal groove, a fuse link through the casing with ends thereof hooked throughout said grooves, and internally screw threaded tubular terminals engaging said ferrule, each of said tubular terminal members provided with an indentation in the rim thereof to engage with portions of said ends of the link bent from the grooves to interlock said elements and keep the fuse assembled.

FRANKLIN S. KLEIN.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2680173 *Aug 6, 1951Jun 1, 1954Chase Shawmut CoElectric fuse
US5187008 *Mar 20, 1991Feb 16, 1993The United States Of America As Represented By The Secretary Of CommerceProcess for the preparation of fiber-reinforced ceramic matrix composites
Classifications
U.S. Classification337/234, 337/237
International ClassificationH01H85/00, H01H85/045
Cooperative ClassificationH01H85/0456, H01H85/0458
European ClassificationH01H85/045G, H01H85/045E