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Publication numberUS3778740 A
Publication typeGrant
Publication dateDec 11, 1973
Filing dateMar 17, 1972
Priority dateFeb 19, 1971
Publication numberUS 3778740 A, US 3778740A, US-A-3778740, US3778740 A, US3778740A
InventorsGaia A, Urani A
Original AssigneeMc Graw Edison Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Protectors for electric circuits
US 3778740 A
Abstract  available in
Images(2)
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Claims  available in
Description  (OCR text may contain errors)

United States Patent 1191 Gaia et al.

[ Dec. 11, 1973 PROTECTORS FOR ELECTRIC CIRCUITS Primary ExaminerBernard A. Gilheany [75] Inventors: Aldino J. Gaia; Angelo Urani, both Ass'stam Exammer F' Bell of St. Louis Mo AttorneyEdmund C. Rogers et al.

[73] Assignee: llficGraw-Edison Company, Elgin, 57 ABSTRACT I An electric fuse has a cup-like housing that is subdi- [22] Filed: Mar. 17, 1972 vided into two separate compartments by a partition; I and each compartment has a fusible element therein [21] Appl' 235310 which is embedded within arc-extinguishing material. Related U.S. Application Data A portion of the partition projects beyond the cup-like 2 Division f Set 116,319 19, 1971, pat housing to enter a slot in a fuseholder to automatically 3 739 313 align the terminals of the electric fuse with the fusereceiving terminals of the fuseholder. An indicating [52] U.S. Cl 337/187, 337/189, 337/206, p is Connected in Parallel with One Of the usib e 337/265 elements, and a second indicating lamp is connected [51] Int. Cl. H0111 85/02 in parallel with the other fusible m an t [58] Field of Search 337/187, 188, 189, ductors which connect those n ng l mps to he 337/13 1 6 206 265 load terminals of the fuseholder are spaced far enough apart to prevent arc over" but are close enough to [56] Referen e Cit d each other to capacitively couple those lamps together UNITED STATES PATENTS in the event a transitory fault causes both of those fusible elements to blow and both of those lamps to be- 2,4l7,692 3/1947 Kline 337/188 3,139,499 6/1964 Cosgrove 337/188 mummated 11 Claims, 13 Drawing Figures J, 236 /2# y 1 2, 202 /f6 236 8 /72 2/4 36- 42/4 /20 20 ZZ@ Z20 6* 20? 4 0 lzaz 72 PAIENTEUBEBI 1 I913 5718.140

I SHEET 1 0F 2 FIG' 2 PROTECTORS FOR ELECTRIC CIRCUITS This is a division of application Ser. No. 116,819 filed Feb. 19, 1971, now US. Pat. No. 3,739,313.

This invention relates to improvements in Protectors For Electric Circuits. More particularly, this invention relates to improvements in electric fuses and fuseholders therefor.

It is, therefore, an object of the present invention to provide an improved electric fuse and an improved fuseholder therefor.

The electric fuse provided by the present invention has a cup-like housing that is subdivided into two separate compartments by a partition; and each compartment has a fusible element therein which is embedded within arc-extinguishing material. That partition will keep metal vapors, that may form as one or the other of the fusible elements blows, from passing into the other compartment. A portion of the partition projects beyond the cup-like housing to enter a slot in a fuseholder to automatically align the terminals of the electric fuse with the fuse-receiving terminals of the fuseholder. As a result, the partition of the electric fuse provided by the present invention performs a dual function namely, it subdivides the housing into two separate compartments, and it automatically aligns the terminals of the electric fuse with the fuse-receiving terminals of a fuse-holder. It is, therefore, an object of the present invention to provide an electric fuse with a partition which subdivides the cup-like housing of that electric fuse into two separate compartments and which also acts as an aligning blade.

The cup-like housing of the electric fuse provided by the present invention is closed by a closure which has a slot therein that accommodates that part of the partition which acts as an aligning blade; and portions of that partition underlie portions of that closure. Sealing material seals the joint between the aligning blade and the slot in the closure, and further sealing material seals the periphery of the closure to the cup-like housing. As a result, that cup-like housing can prevent any loss of the arc-extinguishing material therein; and it also can prevent the escape therefrom of any metal vapors that develop as a fusible element, within that cup-like housing, fuses. It is, therefore, an object of the present invention to provide the closure of a cup-like housing of an electric fuse with a slot that accommodates, and that can be sealed to, the aligning blade of that cup-like housing.

The fuseholder of the present invention has L-shaped line terminals and has L-shaped load terminals. The feet of the line terminals confront and extend toward each other, and thus space the remaining portions of those line terminals apart appreciable distances. The feet of the load terminals confront and extend toward each other, and thus space the remaining portions of those load terminals apart appreciable distances. The feet of the line and load terminals are connected to the fuse-receiving terminals of the fuseholder; and hence the remaining portions of those line and load terminals are spaced further apart than are those fuse-receiving terminals. It is, therefore, an object of the present invention to provide a fuseholder with L-shaped line and load terminals that have the feet thereof confronting and extending toward each other and that are connected to the fuse-receiving terminals of the fuseholder.

The fuseholder of the present invention has an externally threaded boss that has fuse-receiving terminals therein, has a second boss that is displaced from that externally threaded boss, has an indicating lamp in register with an opening in that second boss, and has a nut that coacts with the externally threaded boss to hold the fuseholder in assembled relation with a panel. That panel has an opening which accommodates the externally threaded boss and has a second opening which accommodates the second boss. A fuse, at the front side of the panel, will have the terminals thereof held by the fuse-receiving terminals in the externally threaded boss; and the blowing of that fuse will be readily apparcut because light will pass forwardly from the indicating lamp through the opening in the second boss.

In many installations where electric fuses are used, it is desirable that a neon lamp glow continuously subsequent to the blowing of a fuse; and, in recognition of that fact, fuseholders have been proposed which would illuminate a neon lamp whenever a fuse therein opened a power-supplying circuit. Where a fuse opens a power supplying circuit in response to a fault that is of a continuing nature, that fault can establish and maintain an indicating circuit which includes the neon lamp, and thus can keep that neon lamp glowing continuously. However, if the fault which causes the fuse to open the power-supplying circuit is of a transitory nature, that fault can establish an indicating circuit that will illuminate the neon lamp, but that fault will be incapable of maintaining that indicating circuit and thus will be incapable of making certain that the neon lamp continues to glow. In some cases, the elongated conductors which extend from the fuse panel to the load are long enough, and are in such close proximity to each other, that they can act as the plates of a capacitor; and thus can keep the neon lamp of an indicating circuit flowing even though the fault which blew the fuse and illuminated the neon lamp subsequently clears. In certain installations, however, the lengths and placements of the conductors, which extend between the fuse panel and the load, can not be relied upon to provide sufficient capacitance to keep the neon lamp of an indicating circuit glowing after the fault has cleared. Consequently, it would be desirable to provide a fuseholder which could assure continued energization of a neon lamp even where the fault, that caused the electric fuse in that fuseholder to blow, was of short duration. The present invention provides such a fuseholder; and it does so by mounting within that fuseholder conductors which are interposed between the electric fuse and the load terminals of that fuseholder and which are close enough to each other to act as a capacitor and thereby maintain a neon lamp aglow after a fault, of temporary nature, has blown the electric fuse and has initiated the glowing of that neon lamp. It is, therefore, an object of the present invention to provide a fuseholder which has conductors intermediate the electric fuse and the load terminals and which are so close to each other that they can act as the plates of a capacitor, and can thus keep an indicating neon lamp glowing after a fault of short duration has blown the fuse and has illuminated that neon lamp.

The electric fuse provided by the present invention has a circuit board-on which the conductors between the fuse terminals and the load terminals are formed. As a result, the spacing between those conductors can be precisely determined and continuously maintained.

The circuit board of the fuseholder provided by the present invention also has an indicating lamp thereon; and, in addition, has a pin adjacent that indicating lamp. The fuseholder has a recess which accommodates the indicating lamp, and also has a small-diameter socket which receives the pin adjacent that indicating lamp. The pin on the circuit board and the socket for that pin will align the indicating lamp with the recess therefor in the fuseholder; and the positioning of that pin within that socket will prevent appreciable shifting of that indicating lamp relative to the recess therefor. The lamp-receiving recess has a window therein, and the engagement between the pin on the circuit board and the socket in the fuseholder will hold the indicating lamp in register with the window in that recess.

Other and further objects and advantages of the present invention should become apparent from an examination of the drawing and accompanying description.

In the drawing and accompanying description, a preferred embodiment of the present invention is shown and described, but it is to be understood that the drawing and accompanying description are for the purpose of illustration only and do not limit the invention and that the invention will be defined by the appended claims.

In the drawing, FIG. 1 is a front elevational view of preferred embodiments of a fuseholder and electric fuse that are made in accordance with the principles and teachings of the present invention,

FIG. 2 is a sectional view, on a larger scale, through the fuseholder of FIG. 1, and it is taken along the plane indicated by the line 2-2 in FIG. 1,

FIG. 3 is a sectional view, on the scale of FIG. 2, through the electric fuse and fuseholder of FIG. l, and it is taken along the plane indicated by the line 3-3 in FIG. 1,

FIG. 4 is a sectional view, on the scale of FIG. 2, through the electric fuse and fuseholder of FIG. I, and it is taken along the plane indicated by the line 44 in FIG. 1,

FIG. 5 is a partially broken-away rear view, on the scale of FIG. 1, of the fuseholder shown in FIG. ll,

FIG. 6 isa sectional view, on the scale of FIG. ll, through the fuseholder of FIG. I, and it is taken along the plane indicated by the line 66 in FIG. 5,

FIG. 7 is a sectional view, on the scale of FIG. 2, through the electric fuse and fuseholder of FIG. I, and it is taken along the broken plane indicated by the broken line 7-7 in FIG. 5,

FIG. 8 is an exploded view of the fuseholder of FIG. 1,

FIG. 9 is an exploded view of the electric fuse of FIG.

FIG. 10 is a perspective view of the circuit board for the fuseholder of FIG. 1,

FIG. 11 is a perspective view of part of the electric fuse shown in FIG. 1,

FIG. 12 is an end view of the aligning blade of the electric fuse of FIG. 1, and it shows by dotted lines how that aligning blade could be made with different widths, and

FIG. 13 is an end view of the aligning blade of the electric fuse of FIG. 1, and it shows by dotted lines how that aligning blade could be made with different thicknesses.

Referring to the drawing in detail, the numeral 20 generally denotes a preferred embodiment of fuseholder that is made in accordance with the principles and teachings of the present invention; and that fuseholder has an externally threaded boss 22. Four shouldered recesses 24, 26, 28 and 30 are formed in the boss 22; and each of those shouldered recesses has a relatively large diameter portion that opens to the front surface of that boss and has a smaller-diameter portion that opens to the rear surface of the fuseholder 20. A slot 32 is formed in the boss 22, as shown particularly by FIG. 8; and that slot extends an appreciable distance inwardly of the front surface of that boss, as shown particularly by FIG. 7. An annular recess 34 is formed in the front surface of the boss 22, as shown particularly by FIGS. 7 and 8. The outer diameter of the annular recess 34 is slightly smaller than the root diameter of the external thread on the boss 22.

A generally L-shaped recess 36 is formed in the rear face of the fuseholder 20; and that recess communicates with the shouldered recess 26. A generally L- shaped recess 38 is formed in the rear face of the fuseholder 20; and that recess communicates with the shouldered recess 24. A short, transversely directed recess 40 is formed in the rear face of the fuseholder 20; and that recess communicates with the shouldered recess 28. A short, transversely directed recess 42 is formed in the rear face of the fuseholder 20; and that recess communicates with the shouldered recess 30. A partition 44, which is shown particularly in FIG. 4, is provided between the L-shaped recess 36 and the short, transversely directed recess 40. As shown particularly by FIG. 6, the partition 44 also extends between the L-shaped recess 38 and the short, transversely directed recess 42. A partition 46 is displaced from the partition 44 by and one end of the partition 46 separates portions of the L-shaped recesses 36 and 3:8, as shown by FIG. 7, while the other end of that partition separates portions of the short, transversely directed recesses 40 and 42, as shown by FIG. 5.

A relatively large, rectangular recess 48 is formed in the rear face of the fuseholder 20; and part of that recess underlies a shallow cylindrical boss 56 that projects forwardly from the front surface of that fuseholder. A smaller but deeper rectangular recess 50 directly underlies the boss 56; and the rear of that recess is in communication with'the recess 48, as shown by FIG. 3. A small diameter, cylindrical socket 52 is provided in the boss 56; and that socket extends from the forward surface of that boss to the recess 48, as shown by FIG. 3. A small diameter, cylindrical socket 54 also is formed in the boss 56; and that socket also extends from the forward surface of that boss to the recess 48, as shown by FIG. 3. Circular openings 58 and 60 are formed in the front surface of the boss 56; and a transparent plate 62 is disposed within the recess 50 immediately adjacent the openings 58 and 60 that transparent plate serving as windows for those openings. A transparent sealing material, now shown, is disposed within the openings 58 and 60 to coact with the transparent plate 62 to provide a water-tight closing of those openings. A raised arrow 64 is formed on the forward face of the boss 56 adjacent the cylindrical socket 54; and a raised arrow 66 is formed on that forward face adjacent the cylindrical socket 52. As indicated particularly by FIGS. 1 and 8, the raised arrow 66 points to the left, and thus generally toward the opening 60; whereas the raised arrow 64 points to the right, and thus generally toward the opening 58. An opening 68 is provided in the fuseholder 20 adjacent one side of that fuseholder, as shown particularly by FIGS. 5 and 7. A similar opening, not shown, is provided in the fuseholder adjacent the opposite side of that fuseholder.

The numeral 69 denotes a notch at one side of the rear face of the fuseholder 20, and the numeral 71 denotes a notch at the opposite side of that rear face; all as indicated by FIG. 5. The numerals 73 and 75 denote notches at one end of the rear face of the fuseholder 20, as indicated by FIG. 8.

The numeral 72 denotes an O-ring which is disposed within the annular recess 34 in the forward surface of the boss 22. That O-ring is circular in cross section; and the normal, unstressed diameter of a circular cross section of that O-ring is greater than the depth of the annular recess 34. As a result, whenever the O-ring 72 is in its unstressed condition, the outer face of that O-ring will project outwardly beyond the outer face of the boss 22 of the fuseholder 20.

The numeral 74 denotes a shouldered conductor which is disposed within the shouldered recess 26 in the fuseholder 20. Thelarge diameter portion of the shouldered recess 26 accommodates a tulip-type socket in the large diameter end of the conductor 74, the smaller diameter portion of the shouldered recess 26 accommodates an intermediate-diameter portion of the conductor 74, and a small diameter end portion of that conductor projects rearwardly beyond the recess 36. The numerals 76, 78 and 80 denote conductors which are identical to the conductor 74; but those conductors are disposed, respectively, within the shouldered recesses 28, 30 and 24 of the fuseholder 20. A generally L- shaped conductor 82 has an opening 84 in the foot thereof which receives the intermediate-diameter portion of the conductor 80, as shown particularly by FIG. 7. The L-shaped conductor 82 has a reduced-width portion 86 adjacent the outer end thereof, and it has an offset 87 intermediate the opening 84 and the reducedwidth portion 86; all as shown by FIG. 8. The outer end of the L-shaped conductor 82 extends through the notch 73 in the rear face of the fuseholder 20. The numeral 88 denotes an L-shaped conductor which is the mirror image of the L-shaped conductor 82. The opening 90 in the foot of the L-shaped conductor 88 receives the intermediate-diameter portion of the conductor 74, as shown by FIG. 7. The L-shaped conductor 88 has a reduced-width portion 92 adjacent the outer end thereof, and it has an offset 93 between that reduced-width portion and the opening 90; all as shown by FIG. 8. The outer end of the L-shaped conductor 88 extends through the notch 75 in the rear face of the fuseholder 20. The numeral 94 denotes a wire-securing connector which is mounted on the reduced-width portion 86 of the L-shaped conductor 82', and the numeral 96 denotes a wire-securing connector which is mounted on the reduced-width portion 92 of the L- shaped conductor 88.

The numeral 98 denotes an L-shaped conductor which has an opening 100 in the foot thereof; and that opening accommodates the intermediate-diameter portion of conductor 78. The outer end of the L-shaped conductor 98 has a threaded opening 102 therein which receives the shank ofa screw 104. A lock washer 106 will be telescoped over the shank of that screw before that shank is threaded into the opening 102. An offset 107 is provided intermediate the openings 100 and 102 in the L-shaped conductor 98. The numeral 108 denotes an L-shaped conductor which is the mirror image of the L-shaped conductor 98. An opening 110 in the foot of the L-shaped conductor 108 accommodates the intermediate-diameter portion of the conductor 76. A threaded opening 111 in the outer end of the L-shaped conductor 108 accommodates the shank of a screw 112; and that shank will pass through a lock washer before it is seated in the threaded opening 111. An offset 113 is provided in the L-shaped conductor 108 intermediate the openings 110 and 111.

The numeral 114 denotes a rivet which is mounted within the opening 68 in the fuseholder 20. A similar rivet, not shown, is disposed within the opening in the opposite side of the fuseholder 20. The numeral 118 denotes a gasket which is generally rectangular in configuration, which has an opening that encircles and closely fits the externally threaded boss 22, and which has a second opening that encircles and closely fits the boss 56. As indicated particularly by FIGS. 1 and 8, the dimensions of the gasket 118 are just slightly smaller than the dimensions of the fuseholder 20.

The numeral 120 denotes a circuit board which is made of insulating material; and that circuit board is provided with openings 122 and 124 to accommodate shouldered pins 154 and 156, respectively, as shown by FIG. 3. The openings 122 and 124, and the shouldered pins 154 and 156 held thereby, are in register with the sockets 52 and 54 in the boss 56. The circuit board 120 also has openings 126 and 128 which accommodate the rear ends of the glass envelopes for neon lamps 158 and 160, respectively, as shown in FIG. 2. The circuit board 120 has openings 130 and 132 for leads of the neon lamps 158 and 160, respectively, as shown by FIG. 8; and the circuit board 120 has openings 134 and 136 for terminals of resistors 166 and 170, as indicated by FIG. 8. The circuit board has oenings 138, 140, 142 and 144 to accommodate the small-diameter ends of conductors 80, 74, 78 and 76, respectively.

Conductors 146, 148, 150 and 152 are provided on the rear surface of the circuit board 120, as shown by FIGS. 5 and 10. A mass of solder 162 connects one lead of the lamp 158 to the conductor 152; and a mass of solder 180 connects the other end of that conductor to the small-diameter end of conductor 78 which is disposed within the opening 142 in the circuit board 120. A mass of solder 164 connects one end of the conductor 146 to one terminal of the lamp 160; and a mass of solder 178 connects the other end of that conductor to the small diameter end of the conductor 76 which is disposed within the opening 144 in the circuit board 120. The conductor 148 extends from the shouldered pin 154 to the small diameter end of the conductor 74, which is disposed within the opening in the circuit board 120; and a mass of solder 176 electrically connects the conductor 148 to the small diameter end of conductor 74 and also to one terminal of resistor 170. The other terminal of that resistor is connected to the other terminal of the lamp 160; and a sleeve 172 of insulation encases and protects that connection. The conductor extends from the shouldered pin 156 to the small diameter end of the conductor 80 which is disposed within the opening 138 in the circuit board 120; and a mass of solder 174 electrically connects the conductor 150 to the small diameter end of conductor 80 and also to one terminal of resistor 166. The other terminal of that resistor is connected to the other termiha] of the lamp 158; and a sleeve 168 of insulation encases and protects that connection.

The circuit board 120 and the conductors 146, 148, 150 and 152 thereon can be made in different ways, as desired. Preferably, however, that circuit board and those conductors are made by use of printed circuit board techniques starting with a metal-clad sheet of insulation, using acid-resistant ink to print a pattern on the metal layer of that sheet which is identical to the conductors 146, 148, 150 and 152, and then etching away the rest of that metal layer. As a result, the circuit board 120 can be considered to be a printed circuit board.

The numeral 182 denotes a closure which is intended to underlie and to close the rear face of the fuseholder 20. That closure has a raised surface 184 which confronts and is close to the rear face of the circuit board 120. Elongated bosses 186 and 188 project forwardly beyond the raised surface 184', and those bosses will be disposed within the notches 69 and 71, respectively, at the sides of the rearface of the fuseholder 20. A shouldered passage 190 is formed in the boss 186; and that passage accommodates one end of the rivet 114. As shown particularly by FIG. 7, the rivet 114 will coact with the shouldered passage 190 to help hold the closure 182 in assembled relation with the fuseholder 20. A shouldered passage 192 is provided in the boss 188; and that shouldered passage will receive one end of a rivet, not shown, which is similar to the rivet 114. A suitable sealing material 193 fills and seals the exposed end of the shouldered passage 192, as shown by FIG. 5. Similar sealing material, shown in FIG. 7, will be used to fill and seal the exposed end of the passage 190. Elongated ribs 194 and 196 are provided at the rear face of the closure 182; and those ribs are parallel to the sides of the fuseholder 20. One end of the closure 182 is cut away to define notches 195 and 197; and the notch 195 will expose the screw 104 while the notch 197 will expose the screw 112, when that closure is assembled with the rear face of the fuseholder 20.

The numeral 198 generally denotes an electric fuse which has a generally cup-like housing 200 with an outwardly extending annular flange 202 adjacent the open end thereof, as shown by FIG. 8. The housing 200 has a shallow cylindrical recess'204 in the outer face of the closed end thereof; and an indicia-bearing disc, not shown, can be disposed and held within that recess. That disc could bear the voltage rating and the ampere rating of that electric fuse. The housing 200 has a partition 206 therein; and that partition subdivides the interior of that housing into two separate compartments. In addition, one portion of the partition 206 projects outwardly beyond the open end of the housing 200, as shown particularly by FIG. 9, to constitute an aligning blade. An annular recess 208 is provided inwardly of the outwardly extending annular flange 202, as shown by FIG. 9. The portion of the partition 206 which extends between the annular recess 208 and the inner end of the housing 200 has a width that is equal to the inner diameter of that housing; but the portion of that partition which projects outwardly through and beyond the annular recess 208 has a reduced width, as shown particularly by FIGS. 3 and 9.

A disc-like support 210 of insulating material has a slot 212 therein which is dimensioned to accommodate the outwardly extending portion of the partition 206 of the housing 200. The support 212 is dimensioned to tit neatly within the annular recess 208 in the housing 200. Shouldered pins 214, 216, 218 and 220 are fixedly mounted within four openings in the support 210; and one end of the pin 216 is dimensioned to extend within and to be tightly gripped by the tulip-type socket in the outer end of the conductor 80. The pins 214, 218, and 220 are dimensioned to have the outer ends thereof extend within and to be tightly gripped by the tulip-type sockets in the outer end of conductors 74, 78 and 76, respectively. An opening 222 is formed in the support 210 intermediate the pins 214 and 220; and an opening 224 is formed in that support intermediate the pins 216 and 218. A fusible element 226 is suitably secured to the inner ends of the pins 216 and 218; and a fusible element 228 is suitably secured to the inner ends of the pins 214 and 220. The inner ends of the pins 214, 216, 218 and 220 are dimensioned to hold the fusible elements 226 and 228 within the two compartments defined within the housing 200 by the partition 206, and to hold those fusible elements in spaced relation to the inner surfaces of those compartments. Arc-quenching material 230 is provided within the two compartments in the housing 200 to quickly quench any arc which forms as either of the fusible elements 226 and 228 fuses.

Sealing material 233 is placed in the openings 222 and 224 to close and seal those openings after the arcquenching material has been introduced into the two compartments of the housing 200 via those openings. In addition, sealing material 231 is used to close and seal the joint between the slot 212 in support 210 and the aligning portion of partition 206; and further sealing material 231 is used to close and seal the joint between the periphery of support 210 and the annular recess 208 in the housing 200. That sealing material will coact with that housing, with that partition, and with that support to prevent any leakage of arc-quenching material and to prevent any escape of vapors which develop as one or both of the fusible elements 226 and 228 fuses.

The numeral 232 denotes a nut which has an internal thread that can mate with the external thread on the boss 22. A knurled nut 234 also has an internal thread which can mate with the external thread on the boss 22; and that knurled nut has an inwardly-extending annular flange 236. The inner diameter of the annular flange 236 is larger than the principal diameter of the housing 200 of the electric fuse 198, but is smaller than the outer diameter of the outwardly extending annular .flange 202 on that housing. As a result, the knurled nut 234 can hold the electric fuse 198 in assembled relation with the fuseholder 20.

The feet and the forwardly offset portions of the L- shaped conductors 82, 88, 98 and 108 are disposed within and are quided by the recesses 38, 36, 42 and 40, respectively, in the rear face of the fuseholder 20. The rearwardly-offset outer ends of the L-shaped conductors 82 and 88 constitute the line terminals of the fuseholder 20; and the rearwardly offset portions of the L-shaped conductors 98 and 108 constitute the load terminals of that fuseholder. The mass of solder which surrounds the opening 84 in the foot of the L-shaped conductor 82 electrically bonds and mechanically secures that L-shaped conductor to the conductor 80, and also mechanically secures both of those conductors to the fuseholder 20. Similarly, the masses of solder which surround the openings 90, and 110, respectively, in the L-shaped conductors 88, 98 and 108 electrically bond and mechanically secure those L-shaped conductors to the conductors 74, 78 and 76, respectively. Further, those masses of solder mechanically secure the L-shaped conductors 88, 98, and 108 and the conductors 74, 78 and 76 to the fuseholder 20. The masses of solder 174, 176, 178 and 180 electrically bond conductor 150 to conductor 80, electrically bond conductor 148 to conductor 74, electrically bond conductor 146 to conductor 76, and electrically bond conductor 152 to conductor 78. In addition, the masses of solder 174, 176, 178 and 180 mechanically secure the circuit board 120 to the fuseholder 20. The shouldered pins 154 and 156 will coact with the sockets 52 and 54 in the boss 56 to hold the neon lamps 158 and 160, respectively, in register with the openings 60 and 58 in that boss.

In the preferred embodiments of fuseholder and electric fuse shown in the drawing, the conductors 74, 76, 78 and 80 are oriented and spaced to define a square; and the pins 214, 220, 218 and 216 of the electric fuse 198 are oriented and spaced to define a congruent square. Manufacturing tolerances will, however, keep the orientation and spacing of the pins 214, 220, 218 and 216 from being exactly congruent to the orientation and spacing of the conductors 74, 76, 78 and 80; and this is desirable, because it will increase the contact pressures between those pins and those conductors. Specifically, if manufacturing tolerances cause the axes of the pins 214 and 216 to be spaced further apart than the axes of the conductors 74 and 80, those pins will apply forces to the tulip-type sockets in the forward ends of those conductors which will tend to force the more remotely-located fingers of those tulip-type sockets apart with a force that is greater than normal. The shouldered recesses 26 and 24 closely encircle the fingers of the tulip-type sockets in the forward ends of the conductors 74 and 80; and that close encircling plus the restorative forces within those fingers will enable those fingers to apply substantial contact pressures to the pins 214 and 216. Conversely, if manufacturing tolerances cause the axes of the pins 214 and 216 to be spaced closer together than the axes of the conductors 74 and 80, those pins will apply forces to the tulip-type sockets in the forward ends'of those conductors which will tend to force the more closely located fingers of those tulip-type sockets apart with a force that is greater than normal. The close encircling, by the shouldered recesses 26 and 24, of the fingers of the tuliptype sockets in the forward ends of the conductors 74 and 80 will coact with the restorative forces within the fingers of those conductors to enable those fingers to apply substantial contact pressures to the pins 214 and 216. Similarly, any increases or decreases in the spacings between the axes of the pins 214, 216, 218 and 220, due to manufacturing tolerances, and any increases or decreases in the spacings between the axes of the conductors 74, 80, 78 and 76, due to manufacturing tolerances, will tend to increase the contact pressures between those pins and those conductors. Those increases and decreases in the spacings between the axes of the pins 214, 216, 218 and 220, and those increases and decreases in the spacings between the axes of the conductors 74, 80, 78 and 76, can be along any of the sides ofthe square defined by those pins and also can be along either of the diagonals of that square. Consequently, the manufacturing tolerances of those four pins, of those four conductors, of the support 210, and of the externally threaded boss 22 will make certain that higher-than normal contact pressures will be established and maintained between those pins and those conductors. Such higher than normal contact pressures are desirable, because they increase the current-carrying capability of the combination of fuseholder and electric fuse. All of this means that by providing four fuse terminals on the electric fuse 198 and by providing four complementary fuse-receiving terminals on the fuseholder 20, the present invention enables manufacturing tolerances to effect the development of positive laterally-directed and longitudinally directed forces which develop higher-than normal contact pressures between those terminals.

Whenever the fuse 198 is assembled with the fuseholder 20, the line terminals 82 and 88 are connected to line, and the load terminals 98 and 108 are connected to a load, current will flow via line terminal 82, conductor 80, pin 216, fusible element 226, pin 218, conductor 78, load terminal 98, a conductor, not shown, extending to the load, a further conductor, not shown, extending from the load to load terminal 108, conductor 76, pin 220, fusible element 228, pin 214, and line terminal 88. Essentially no current will flow from conductor via conductor 150, resistor 166, lamp 158, and conductor 152 to conductor 78; because the resistance of the fusible element 226 is so very much smaller than the combined resistances of resistor 166 and lamp 158. Similarly, essentially no current will flow from conductor 74 via conductor 148, resistor 170, lamp 160, and conductor 146 to conductor 76; because the resistance of the fusible element 228 is so very much smaller than the combined resistances of resistor 170 and lamp 160. As a result, the lamps 158 and 160 will normally remain unilluminated, and no light will be visible through the openings 60 and 58 in the boss 56.

In the event a fault develops in the load, not shown, or between the conductors, not shown, which are connected to the load terminals 98 and 108, either or both of the fusible elements 226 and 228 may fuse. If the fusible element 226 fuses, but the fusible element 228 remains intact, current will flow from line terminal 82 via conductor 80, conductor 150, resistor 166, lamp 158, conductor 152, and conductor 78 to the load terminal 98; and that flow of current will illuminate that lamp. As long as the fusible element 228 remains intact, essentially no current will flow through resistor and lamp 160; and hence that lamp will remain unilluminated. The light passing outwardly through the opening 60 in the boss 56 will pass through the opening in the panel, not shown, in which that boss is mounted; and that light will plainly indicate to the maintenance man that the fusible element 226 has blown. The maintenance man will, thereupon, rotate the knurled nut 234 in the counter-clockwise direction in FIG. 8, and

thereby remove that nut from the externally threaded boss 22 which extends through a second opening in the panel, not shown. At such time, the maintenance man can apply an outwardly directed pull to the housing 200 of the electric fuse 198, and thereby separate that electric fuse from the fuseholder 20. A replacement fuse can then have the terminals 214, 216, 218 and 220 thereof aligned, respectively, with the conductors 74, 80, 78 and 76 of the fuseholder 20; and the aligning portion of the partition 206 of that replacement fuse will coact with the slot 32 in the externally threaded boss 22 to insure that alignment. Specifically, the portion of the partition 206 which projects outwardly beyond the annular recess 208 in the housing 200 of the replacement fuse will be longer than the portions of the pins 214, 216, 218 and 220 which project outwardly from the support 210 of that fuse; and hence that portion of that partition will have to be aligned with, and will have to enter, the slot 32 before any of those pins can begin to enter. the tulip-type sockets therefor. As the replacement electric fuse is pressed into engagement with the fuseholder 20, it will apply force to that fuseholder which will tend to move that fuseholder rearwardly and away from the panel, not shown. However, the nut 232 will be solidly seated on the externally threaded boss 22 of that fuseholder, and will thus prevent any such rearward movement. Once the terminals 214, 216, 218 and 220 of the replacement electric fuse have been seated, respectively, within the tulip-type sockets in the forward ends of the conductors 74, 80, 78 and 76, the knurled nut 234 will again be threaded onto the externally threaded boss 22. The annular flange 236 of that knurled nut will overlie the outwardly extending flange 202 on the housing 200 of the replacement electric fuse; and thus will thereby positively prevent accidental separation of that replacement electric fuse from the fuseholder 20.

At the time the fusible element 236 fused, flame and metal vapors may have been evolved; but that flame and those metal vapors could not escape from the housing 200 of the electric fuse 198. Specifically, the sealing material within the opening 224, the sealing material 231 in the joint between the projecting portion of the partition 206 and the slot 212 in the support 210, and the sealing material 231 which seals the circular joint between the periphery of the support 210 and the annular recess 208 in the housing 200 will effectively prevent any escape of flame or metal vapors. The user of the electric fuse and fuseholder provided by the present invention can be assured that the sealing material in the opening 224 and the sealing material 233 in the opening 222 will not be broken by nearby objects; because those openings are disposed, respectively, between the pins 216 and 218 and between the pins 214 and 220. Those pins will project outwardly from the support 210, and will thereby keep any nearby objects from contacting and injuring the sealing material within the openings 224 and 222. The close proximity of the support 210 to the forward face of the externally threaded boss 22, whenever the electric fuse 198 is assembled with the fuseholder 20, and the fact that the O-ring 72 is disposed outwardly of and surrounds the circular joint between the support 210 and the annular recess 208 in the housing 200, will make certain that the said circular joint is protected from nearby objects whenever the electric fuse 198 is in assembled relation with the fuseholder 20. In addition, the knurled nut 234 will provide additional protection for the sealing material in the circular joint between the support 210 and the annular recess 208 in the housing 200, whenever the electric fuse 198 is assembled with the fuseholder and that knurled nut is holding that electric fuse and that fuseholder in such relation.

If the fusible element 228, rather than the fusible element 226, had blown in response to the fault which developed in the load, or in one or both of the conductors connected to the load terminals 98 and 108, the lamp 160, rather than the lamp 158, would have become illuminated. Light from the lamp would then pass 0utwardly through the opening 58 in the boss 56 and would pass through the opening in the panel, not shown, in which that boss is mounted. That light would plainly indicate to the maintenance man that the fusible element 228 had blown. The maintenance man would then replace the electric fuse 198.

If the fault in the load, or in the conductors connected to the load terminals 98 and 108, had caused both of the fusible elements 226 and 228 to blow, both of the lamps 158 and 160 would have become illuminated. As long as that fault persisted, current would flow from line terminal 82 via conductor 80, conductor 150, resistor 166, lamp 158, conductor 152, conductor 78, load terminal 98, the conductor connected between that load terminal and the fault, through the fault to the conductor connected to the load terminal 108, and then via conductor 76, conductor 146, lamp 160, resistor 170, conductor 148, conductor 74, and line terminal 88. The values of the resistors 166 and 170 are high enough so those resistors will protect the lamps 158 and 160 in the event only one of those lamps becomes illuminated; but those values are low enough to enable both of those lamps to become illuminated whenever both of the fusible elements 226 and 228 blow.

In the event a fault which causes both of the fusible elements 226 and 228 to blow is of a transitory nature, and disappears after it has blown those fusible elements and has caused both of the lamps 158 and 160 to become illuminated, that fault will be unable to maintain the circuit which illuminated those lamps. However, those lamps will continue to remain illuminated because of a capacitive effect which is provided by the closely spaced upper ends of conductors 146 and 152, as those conductors are viewed in FIGS. 5 and 10. The spacing between those ends is great enough to prevent arcing over, but is small enough to provide a capacitance which will keep the lamps 158 and 160 illuminated after a transitory fault has caused both of the fusible elements 226 and 228 to blow and hascaused those lamps to become illuminated. This is highly desirable; because it makes certain that the lamps 158 and 160 will remain illuminated, and will thus indicate that a fault occurred, even if that fault subsequently disappearsv It will be noted that the outer ends of the line terminals 82 and 88 are spaced further apart than are the conductors 80 and 74; and it also will be noted that the outer ends of the load terminals 98 and 108 are spaced further apart than are the conductors 78 and 76. This is desirable because it will minimize the likelihood of any arcing over between conductors connected to the line terminals 82 and 88, and also will minimize the likelihood of any arcing over between conductors connected to the load terminals 98 and 108.

The electric fuse 198 andthe fuseholder 20 provided by the present invention can be arranged to prevent the substitution of an electric fuse of an undesired ampere rating for an electric fuse of a desired ampere rating. Specifically, as shown by FIG. 12, the portion of the partition 206 which acts as an aligning blade can be made in different widths; and the slot 32 in the externally threaded boss 22 can be made in different lengths. To prevent over fusing, the smallest ampere-rating fuse to be used with the fuseholder 20 should have the narrowest aligning blade, the largest ampere-rating fuse should have the widest aligning blade, and electric fuses with intermediate ampere ratings should have aligning blades of widths intermediate those of the widest and narrowest aligning blades. The externallythreaded boss 22 should have a slot 32 with a width that would correspond to the width of the aligning blade of the fuse having the desired ampere rating; and no fuse having a larger ampere rating could then be inserted in that Slot.

As indicated particularly by FIG. 13, the aligning portion of the partition 206 of the electric fuse 198 can be given different thicknesses, and the slot 32 in the externally threaded boss 22 of the fuseholder can be provided with corresponding thicknesses. Specifically, the smallest ampere-rating electric fuse to be used with the fuseholder 20 should have the thinnest partition 206, and progressively larger ampere-rating fuses should have progressively thicker aligning blades. The externally threaded boss 22 should have a slot 32 with a thickness that would correspond to the thickness of the aligning blade of the fuse having the desired ampere rating; and no fuse having a larger ampere rating could then be inserted in that slot.

By varying thediameters and the orientations of the pins 214, 216, 218 and 220 of the electric fuse 198, and by correspondingly varying the dimensions and orientations of the conductors 74, 80, 78 and 76, the present invention also can prevent over fusing. As a result, the present invention makes it possible to provide a highly desirable, rating-regulated, combination of electric fuse and fuseholder therefor.

The electric fuse 198 and the fuseholder 20 can be used successfully in a location where moisture and dripping water can be anticipated. Specifically, in such an installation, the nut 232 will hold the front face of the gasket 118 in intimate engagement with the rear face of a panel, such as the panel indicated by dotted lines in FIG. 3; and that intimate engagement will enable that gasket to seal the openings in that panel which accommodate the bosses 22 and 56. As a result, moisture or dripping water will be unable to pass through those openings. Also in such an installation, the O-ring 72 will engage the exposed face of the support 210 of the electric fuse 198, and will coact with that exposed face to form a moisture-resistant and waterproof seal. The overall result is that the electric fuse 198 and the fuseholder 20 can be used successfully in a location where moisture and dripping water can be anticipated.

The lamps 158 and 160, that are mounted within the recess 50 in the boss 56, will preferably be neon lamps: because such lamps can be kept illuminated by the capacitance between the conductors 146 and 152 after a fault has illuminated those lamps and then disappeared. However, in any installation where the anticipated circuit voltage is too low to illuminate a neon lamp, incandescent lamps will be substituted for the neon lamps 158 and 160 while those incandescent lamps will respond to the fusing of the fusible element 226 and 228 to become illuminated, and while those incandescent lamps will remain illuminated as long as the fault which blew those fusible elements persists, those incandescent lamps will darken if that fault disappears. Consequently, the lamps 158 and 160 will preferably be neon lam ps.

Whereas the drawing and accompanying description have shown and described a preferred embodiment of the present invention it should be apparent to those skilled in the art that various changes may be made in the form of the invention without affecting the scope thereof.

What we claim is:

1. A fuseholder which has a housing, a line terminal which is accessible at one side of said housing, a load terminal which is accessible at a second side of said housing, a second line terminal which is accessible at said one side of said housing, a second load terminal which is accessible at said second side of said housing, fuse-receiving terminals which are disposed within said housing and which are intermediate the first said line terminal and the first said load terminal and which are spaced away from said first said line terminal and also are spaced away from said first said load terminal, and further fuse-receiving terminals which are disposed within said housing and which are intermediate said second line terminal and said second load terminal and which are spaced away from said second line terminal and also are spaced away from said second load terminal, the accessibility of said line terminals at said one side of said fuseholder and the accessibility of said load terminals at said other side of said fuseholder minimizing the likelihood of any arcing between one of said line terminals and one of said load terminals, the spacing between the first said and said second line terminals being substantially greater than the spacing between the fuse-receiving terminal connected to the first said line terminal and the further fuse-receiving terminal connected to said second line terminal, whereby the likelihood of any arcing between said line terminals and any line conductors connected thereto is minimized, the spacing between the first said and said second load terminals being substantially greater than the spacing between the fuse-receiving terminal connected to the first said load terminal and the further fuse-receiving terminal connected to said second load terminal, whereby the likelihood of any arcing between said load terminals and any load conductors connected thereto is minimized.

2. A fuseholder as claimed in claim 1 wherein said line terminals are the exteriorly-located ends of conductors which are substantially L-shaped in configuration, wherein the feet of said L-shaped conductors confront and'extend toward each other and space the remaining portions of said L-shaped conductors apart appreciable distances, wherein said feet of said L-shaped conductors are connected to two of said fuse-receiving terminals, wherein said load terminals are the exteriorly-located ends of further conductors which are substantially L-shaped in configuration, wherein the feet of said further L-shaped conductors confront and extend toward each other and space the remaining portions of said further L-shaped conductorsapart appreciable distances, wherein said feet of said further L-shaped conductors are connected to two of said fuse-receiving terminals, and wherein said feet of the first said L-shaped conductors and of said further L-shaped conductors space said remaining portions of said first said L- shaped conductors and of said further L-shaped conductors further apart than the spacing between the first said two fuse-receiving terminals.

3. An electric fuse which comprises a housing, a partition that subdivides said housing into two compartments and that projects outwardly beyond said compartments to constitute an aligning blade, a closure for said housing which has a slot therein that telescopes over said aligning blade, said closure having spaced fuse terminals at one side of said slot that have portions thereof disposable within one of said compartments within said housing and having further spaced fuse terminals at the other side of said slot that have portions thereof disposable within the other of said compartments within said housing, a fusible element that spans the space between said portions of the first said fuse terminals and that is disposable within the first said compartment within said housing, a second fusible element that spans the space between said portions of said further fuse terminals and that is disposable within said second compartment within said housing, said partition keeping any metallic vapors evolved during the fusing of either of said fusible elements from passing into the other compartment within said housing, said aligning blade being disposable within a slot in a fuseholder to automatically align the first said fuse terminals with fuse-receiving terminals therefor in said fuseholder and to align said further fuse terminals with fuse-receiving terminals therefor in said fuseholder.

4. An electric fuse as claimed in claim 3 wherein said housing has an outwardly-extending annular recess therein adjacent the open end thereof and wherein the periphery of said closure is disposed within said outwardly extending annular recess, said partition having portions thereof at the level of and merging smoothly into said outwardly extending annular recess and underlying portions of said closure which are between the ends of said slot and said periphery of said closure, and sealing material that seals the joint between said slot and said aligning blade and seals the joint between said periphery of said closure and said outwardly-extending annular recess.

5. An electric fuse as claimed in claim 3 wherein arcextinguishing material substantially fills said one compartment in said housing and engages and surrounds the first said fusible element, wherein further arcextinguishing material substantially fills said second compartment in said housing and engages and surrounds said second fusible element, wherein sealing material closes an opening in said closure which is in register with said one compartment in said housing and through which the first said arc-extinguishing material was introduced into said one compartment, wherein sealing material closes a second opening in said closure which is in register with said second compartment and through which said further arc-extinguishing material was introduced into said second compartment, and wherein said closed openings in said closure are disposed between said fuse terminals, whereby said fuse terminals will protect the sealing material within said openings from nearby objects.

6. An electric fuse as claimed in claim 3 wherein said fuse terminals project outwardly beyond said closure and are engageable with fuse-receiving terminals in a fuseholder, and wherein said fuse terminals coact with said fuse-receiving terminals in said fuseholder to hold said closure immediately adjacent the surface of said fuseholder, whereby said fuseholder will act to protect said closure from injury whenever said electric fuse is in assembled relation with said fuseholder.

7. A fuseholder which has a plurality of fusereceiving terminals therein, each of said fuse-receiving terminals having a generally-cylindrical end with a tulip-type socket therein, having a small-diameter end, and having an intermediate portion with a diameter smaller than the diameter of said generally cylindrical end but larger than the diameter of said small-diameter end, connecting terminals that have portions thereof disposed externally of said fuseholder and that have portions thereof disposed within said fuseholder and that have openings in the internally disposed portions thereof, said openings in said internally disposed portions of said connecting terminals accommodating and encircling said intermediate portions of said fusereceiving terminals, and solder engaging and electrically bonding together said internally disposed portions of said connecting terminals and said intermediate portions of said fuse-receiving terminals.

8. A fuseholder as claimed in claim 7 wherein a circuit board has openings which telescope over said small-diameter ends of said fuse-receiving terminals, said circuit board having conductors thereon which are soldered to said small-diameter ends of said fusereceiving terminals.

9. A fuseholder as claimed in claim 7 wherein said connecting terminals are generally L-sahped and have said openings therein, which receive said intermediate portions of said fuse-receiving terminals, in the feet thereof, said feet of said connecting terminals confronting and extending toward each other to displace the remaining portions of said conducting terminals from each other by distances greater than the distances between said fuse-receiving terminals.

10. A fuseholder as claimed in claim 7 wherein said connecting terminals have offsets intermediate the ends thereof, said offsets disposing said externally disposed portions of said connecting terminals adjacent the rear of said fuseholder and thereby displacing said externally disposed portions of said connecting terminals rearwardly of any panel with which the front of said fuseholder is associated.

11. A fuseholder which has a body of insulating material with a plurality of passages extending therethrough, fuse-receiving terminals disposed within said passages through said body of insulating material and having the rear ends thereof projecting into a recess adjacent the rear of said body of insulating material, a line terminal extending into said recess in said body of insulating material, a load terminal extending into said recess in said body of insulating material, a circuit board disposed within said recess in said body of insulating material, said line terminal having an opening therein which is disposed within said recess in said body of insulating material and which encircles the rear end of one of said fuse-receiving terminals, a conductor on said circuit board which has an opening therein that encircles said rear end of said one fuse-receiving terminal, said load terminal having an opening therein which is disposed within said recess in said body of insulating material and which encircles the rear end of another of said fuse-receiving terminals, a second conductor on said circuit board which has a second opening therein that encircles said rear end of said second fuse-receiving terminal, solder which electrically connects said line terminal and the first said conductor on said circuit board to said rear end of said one fuse-receiving terminal, and further solder which electrically connects said load terminal and said second connector on said circuit board to said rear end of said second fuse-receiving terminal.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4834664 *Dec 11, 1987May 30, 1989Lin Mei MeiSafety end-connector used for extension cord
US6617974 *May 24, 2001Sep 9, 2003Dan StanekMultiple pole fused disconnect
US6700768 *Oct 17, 2002Mar 2, 2004Patent-Treuhand-Gesellschaft Fur Elektrische Gluhlampen MbhFuse housing
Classifications
U.S. Classification337/187, 337/265, 337/206, 337/189
International ClassificationH01H85/045, H01H85/20, H01H85/00, H01H85/32
Cooperative ClassificationH01H85/0452, H01H85/32, H01H85/205
European ClassificationH01H85/32, H01H85/20L, H01H85/045B
Legal Events
DateCodeEventDescription
Feb 3, 1986ASAssignment
Owner name: COOPER INDUSTRIES, INC., 1001 FANNIN, HOUSTON, TEX
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:MCGRAW-EDISON COMPANY;REEL/FRAME:004510/0810
Effective date: 19860130