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US3568122A - Protector for electric circuits - Google Patents

Protector for electric circuits Download PDF

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Publication number
US3568122A
US3568122A US864672A US3568122DA US3568122A US 3568122 A US3568122 A US 3568122A US 864672 A US864672 A US 864672A US 3568122D A US3568122D A US 3568122DA US 3568122 A US3568122 A US 3568122A
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United States
Prior art keywords
fusible element
opening
contact areas
electric fuse
support
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US864672A
Inventor
Angelo Urani
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Cooper Industries LLC
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McGraw Edison Co
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Assigned to COOPER INDUSTRIES, INC., A CORP. OF OH. reassignment COOPER INDUSTRIES, INC., A CORP. OF OH. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: MCGRAW-EDISON COMPANY
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H85/00—Protective devices in which the current flows through a part of fusible material and this current is interrupted by displacement of the fusible material when this current becomes excessive
    • H01H85/02—Details
    • H01H85/04—Fuses, i.e. expendable parts of the protective device, e.g. cartridges
    • H01H85/041—Fuses, i.e. expendable parts of the protective device, e.g. cartridges characterised by the type
    • H01H85/0411—Miniature fuses
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H85/00—Protective devices in which the current flows through a part of fusible material and this current is interrupted by displacement of the fusible material when this current becomes excessive
    • H01H85/02—Details
    • H01H85/0241—Structural association of a fuse and another component or apparatus
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H85/00—Protective devices in which the current flows through a part of fusible material and this current is interrupted by displacement of the fusible material when this current becomes excessive
    • H01H85/0013—Means for preventing damage, e.g. by ambient influences to the fuse
    • H01H85/0017—Means for preventing damage, e.g. by ambient influences to the fuse due to vibration or other mechanical forces, e.g. centrifugal forces

Definitions

  • PROTECTOR FOR ELECTRIC CIRCUITS This invention relates to improvements in Protectors For Electric Circuits. More particularly, this invention relates to improvements in low amperage electric fuses.
  • the fusible elements that are used in low amperage electric fuses have such small diameters that those fusible elements tend to be quite fragile. As a result, those fusible elements should be protected against injury during the manufacture, shipment and use of the low amperage electric fuses of which they are component parts.
  • the fusible element of the present invention is protected against injury, during the manufacture, shipment and use of the low amperage electric fuse of which it is a component part, by being mounted adjacent a longitudinally extending central opening within a support and by being made so it is undulatory in configuration.
  • the fusible element of the present invention is resistant to injury,.during the manufacture, shipment and use of the low amperage electric fuse of which it is a component part. It is, therefore, an object of the present invention to provide a low amperage electric fuse which has the fusible element thereof of undulatory configuration and mounted adjacent a longitudinally extending central opening within a support.
  • the present invention fixes the effective length of the fusible element of the low amperage electric fuse thereof by forming precisely spaced contact areas at the ends of the longitudinally extending opening in the support for that fusible element and by forming notches in the ends of that support to fix the positions of the ends of that fusible element relative to those contact areas.
  • the sides of the notches in the ends of the support for the fusible element are inclined relative to each other to make those notches generally V-shaped in configuration;
  • those notches enable moderate forces, applied to the ends of the fusible element, to guide those ends into predetermined positions relative to the contact areas on that support.
  • the use of such moderate forces is important, because such forces will not stretch or distort the fusible element.
  • the overall result is that the effective length of the fusible element of the low amperage electric fuse of the present invention can be easily and accurately fixed. It is, therefore, an object of the present invention to provide a support, for the fusible element of an electric fuse, which has precisely shaped contact areas. at the ends of a longitudinally extending opening therein and which has generally V-shaped notches in the ends thereof to enable moderate fuses to guide the ends of that fusible element into predetermined positions relative to those contact areas.
  • FIG. 1 is an enlarged, longitudinal, sectional view through one preferred embodiment of low amperage electric fuse that is made in accordance with the principles and teachings of the present invention
  • FIG. 2 is an enlarged, longitudinal, sectional view which is similar to that of FIG. 1 but wherein the electric fuse has been rotated about the longitudinally extending axis thereof:
  • FIG. 3 is a sectional view, on a still large scale, through the electric fuse of FIG. 1, and it is taken along the plane indicated by the lines 3-3 in FIG. 1;
  • FIG. 4 is a sectional view, on the scale of FIG. 3, through the electric fuse of FIG. 1, and it is taken along the plane indicated by the line 44 in FIG. 3;
  • FIG. 5 is a perspective view of a second preferred embodiment of low amperage electric fuse that is made in accordance with the principles and teachings of the present invention.
  • FIG. 6 is a broken-away, elevational view of an electromagnetic coil in which the electric fuse of FIG. 5 is embedded;
  • FIG. 7 is a sectional view, on a larger scale, through the electric fuse of FIG. 5, and it is taken along the plane indicated by the line 77 in FIG. 6;
  • FIG. 8 is a sectional view which is similar to that shown in FIG. 7 but wherein part of the insulation for the electromagnetic coil has engaged and moved part of-the fusible element.
  • the numeral 20 denotes a support which is made from an insulating material which can withstand the temperatures used in soldering, which can have an opening and notches formed therein by a punching operation, and which is dimensionally stable. While different materials could be used in making the support 20, phenolic resins have been found to be very useful.
  • the numeral 22 denotes a longitudinally directed, rectangular opening in the support 20, As emphasized by FIGS. 1 and 2, that opening is spaced inwardly from each side of the support 20, and also is spaced inwardly from each end of that support. In actual practice, the geometric center of the opening 22 is coincident with the geometric center of the support 20.
  • the numeral 24 denotes the V-shaped entrance of an aligning notch 26 in the left-hand end of the support 20; and the geometric centers of the notch and of that V-shaped entrance lie on the longitudinally directed center line of that support.
  • the numeral 28 denotes the V-shaped entrance of an aligning notch 30 in the right-hand end of the support 20; and the geometric centers of that notch and of that V-shaped entrance lie on the l0ngitudinally directed center line of that support.
  • the numeral 32 denotes a contact area which overlies the upper surface of the left-hand end of the support 20; and that contact area is made from a metal with which solder can readily alloy.
  • the right-hand edge of the contact area 32 terminates adjacent the left-hand end of the opening 22 in the support 20.
  • the numeral 34 denotes a contact area which overlies the upper surface of the right-hand end of the support 20; and that contact area is made from a metal with which solder can readily alloy.
  • the left-hand edge of the contact area 34 terminates adjacent the right-hand end of the opening 22.
  • the opening 22 will preferably be formed by a punching operation, and thus may have minute burrs or projections at the ends thereof, the confronting edges of the contact areas 32 and 34 are spaced outwardly from the ends of the opening 22.
  • the V- shaped entrances 24 and 28 and the notches 26 and 30 also will preferably be formed by a punching operation; and in actual practice, the opening 22, the V-shaped entrances 24 and 28, and the notches 26 and 30 are all punched at the same time.
  • the numeral 36 denotes a wirelike fusible element of small diameter; and that diameter will vary with the ampere rating of the electric fuse. However, in all cases, the diameter of that fusible element will be very much smaller than that shown in FIGS. 1-4.
  • the numeral 38 denotes a portion of the fusible element 36 which has been bent downwardly through the notch 26 and then bent into engagement with the bottom surface of the support 20.
  • the numeral 40 denotes a portion of the fusible element 36 which has been bent downwardly through the notch 30 and then bent into engagement with the support 20.
  • the fusible element 36 has a series of reverse bends therein; and those bends provide an undulatory configuration for that fusible element.
  • the V-shaped entrances 24 and 28 and the notches 26 and 30 will enable the assembler to use only moderate forces in guiding the ends of the fusible element 36 into registry with the longitudinally directed center line of the support 20.
  • the use of moderate forces is important, because such forces will not stretch or distort that fusible element.
  • the V-shaped entrances 24 and 28' and the notches 26 and 30 will, after the portions 38 and 40 of the fusible element 36 have been bent downwardly through the notches 26 and 30 and then into engagement with the bottom surface of the support 20, help hold that fusible element in registry with the longitudinally directed center line of that support.
  • the V-shaped entrances 24 and 28 and the notches 26 and'30 again will enable moderate forces to be used in guiding the ends of the fusible element 36 into registry with the longitudinally directed center line of the support 20.
  • the V-shaped entrances 24 and 28 and the notches 26 and 30 will, after the portions 38 and 40 of the fusible element 36 have been bent downwardly through the notches 26 and 30 and then into engagement with the bottom surface of the support 20, help hold that fusible element in registry with the longitudinally directed center line of that support.
  • the contact area 32 and the contact area 34 can be made in different ways.
  • One preferred way of making those contact areas is to form spaced layers of copper on the upper surface of the support 20, and then form coatings of tin on those spaced layers of copper. When made in that way, the contact areas 32 and 34 will have upper surfaces with which solder can readily alloy.
  • the numeral 42 denotes solder which bonds the left-hand end of the fusible element 36 to the contact area 32 and the numeral 43 denotes solder which bonds the right-hand end of that fusible element to the contact area 34.
  • the solder 42 and 43 will not only electrically bond, but also will mechanically secure, the fusible element 36 to the contact areas 32 and 34.
  • the numeral 46 denotes a wirelike connecting element which is made from a metal having a low resistivity and a relatively high degree of ductility.
  • the inner end of the connecting element 46 overlies a portion of the contact area 32 and is electrically bonded, and mechanically secured, to that contact area by solder 48.
  • the numeral 50 denotes a wirelike connecting element which is similar to the connecting element 46.
  • the inner end of the connecting element 50 overlies a portion of the contact area 34 and is electrically bonded, and mechanically secured, to that contact area 34 by solder 52. While the connecting elements 46 and 50 could be made of different metals, copper has been found to be very useful.
  • solder 42 is shown as being separate and discrete from the solder 48
  • the solder 48 merges with and becomes almost indistinguishable from the solder 42.
  • solder 43 is shown as being separate and discrete from the solder 52
  • the solder 52 merges with and becomes almost indistinguishable from the solder 43.
  • the source of heat for the soldering operation will be spaced from the left-hand end of the fusible element 36 so that source of heat will not interfere with the positioning of that fusible element in register with the longitudinally directed center line of the support 20.
  • the source of heat for the soldering operation will be spaced from the right-hand end of the fusible element 36 so that source of heat will not interfere with the positioning of that fusible element in register with the longitudinally directed center line of the support 20.
  • the numeral 54 denotes a tubular casing of insulating material for the electric fuse of the present invention; and the inner diameter of that casing is large enough to permit the support 20 to be telescoped freely within thatcasing. As shown by FIGS. 1 and 2, the casing 54 is considerably longer than the support 20; and that support has the ends thereof spaced inwardly from the opposite ends of that casing. While the casing a 54 can be made of different materials, glass has been found to be very useful.
  • the outer end of the connecting element 46 is bent around the left-hand end of the casing 54, and then is bent into engagement with a portion of the outer surface of that casing.
  • the outer end of the connecting element 50 is bent around the right-hand end of the casing 54, and then is bent into engagement with a portion of the outer surface of that casing.
  • the numeral 56 denotes a ferrulelike terminal; and the inner diameter of that terminal is large enough to enable that terminal to be telescoped over the left-hand end of the casing -54 and over the bent outer end of the connecting element 46.
  • the numeral 58 denotes a mass of solder which electrically bonds the connecting element 46 to the terminal 56.
  • the numeral 62 denotes a ferrulelike terminal which is similar to the ferrulelike terminal 56.
  • the inner diameter of the terminal 62 is large enough to enable that terminal to be telescoped over the right-hand end of the casing 54 and over the bent outer end of the connecting element 50.
  • the numeral 64 denotes a mass of solder which electrically bonds the connecting element 50 to the terminal 62.
  • the contact areas 32 and 34 are formed on the opposite ends of the upper surface of the support 20. Thereafter, the opening 22, the V-shaped entrances 24 and 28, and the notches 26 and 30 are formed by a punching operation. While the punch and die that are used in forming the opening 22, the V-shaped entrances 24 and 28, and the notches 26 and 30 will be designed to leave the ends of the opening 22 as free from burrs and rough sports as possible, some burrs and some rough spots will be formed at those ends.
  • those burrs and rough spots will have heights less than the thicknesses of the contact areas 32 and 34; and hence those contact areas will space the portions of the fusible element 36, which are in register with the ends of the opening 22, away from those ends. This means that burrs and rough spots on the ends of the opening 22 will be unable to cut or otherwise impair the fusible element 36 as that fusible element is assembled with the support 20.
  • the ampere rating of the electric fuse will be stamped into the bottom surface of the support 20. In the preferred embodiment of electric fuse shown by FIGS. 1-4, the ampere rating is 1 A, and hence a l and a /4 are stamped into the bottom surface of the support 20.
  • the curved inner ends of the notches 26 and 30 will help guide the ends of the fusible element 36 into registry with that longitudinally directed center line; and then the assembler, or the machine which is used in fabricating the electric fuse, will bend the ends of that fusible element downwardly through the notches 26 and 30 into engagement with the bottom surface of the support 20. Once the ends of the fusible element 36 have been bent into engagement with that bottom surface, any excess lengths of those ends can be cut away; and, thereafter, no further handling of the fusible element 36 will be required. This is desirable, because it minimizes the risk of breaking or fatiguing that small diameter, inherently fragile, fusible element.
  • the connecting elements 46 and 50 will then be disposed so the confronting ends thereof overlie the contact areas 32 and 34; and then the solder 42, 43, 48 and 52 will be applied to those contact areas to electrically bond, and mechanically secure, those connecting elements and the fusible element 36 to those contact areas.
  • the solder 42 will flow up to, but will stop at, the right-hand edge of the contact area 32; and the solder 43 will flow up to, but will stop at, the left-handedge of the contact area 34.
  • Theportion of the fusible element 36 which is disposed between the confronting edges of the contact areas 32 and 34 is the effective length of that fusible element; and that effective length will be fixed by the precise spacing between the confronting edges of the contact areas 32 and 34 and by the positioning of that fusible element so it is generally parallel to the longitudinally directed center line of the support 20.
  • the numeral 70 generally denotes a second embodiment of electric fuse that is made in accordance with the principles and teachings of the present invention. That second embodiment can be identical with the embodiment shown in FIGS. 1-4, except for the fact that it isnot enclosed within a casing such as the casing 54.
  • a casing such as the casing 54.
  • the electric fuse 70 will be directly embedded within an of turns thereof; .and two of those layers are denoted by the numerals 74 and 76.
  • the coil 72 has an outer layer 78 of insulation. While the layers 74, 76 and 78 of insulation are shown by FIGS. 7 and 8 as being spaced apart, those layers will usuallybe parts of one continuous strip of insulation.
  • the connecting elements 46 and 50 .of the electric fuse 70 of FlGS.5-8 are connected to portions of the terminal 80 of the coil 72, and thus are connected in series with that terminal, with the coil 72, and with the terminal 82. in the event that coil is subjected to a potentially hurtful overload, the fusible element 36 will fuse and thereby prevent an electrical fire.
  • the bottom surface of the support will be disposed against the layer 76, and then the outer layer 78 will be placed adjacent the upper surface of that support. That outer layer may bear against the upper surface of the fusible element 36, but the reverse bends in that fusible element will space many portions of that fusible element away from that outer layer. This is desirable; because it will keep the outer layer 78 from absorbing undue amounts of heat from those portions of the fusible element 36.
  • the portions of the support 20 which define, and which extend outwardly from, the central opening 22 will tend to protect the fusible element 36 by holding objects away from the sides of that fusible element. As a result, the sides of that fusible element are protected from injury while the electric fuse 70 is being manufactured, shipped and used. Because the fusible element 36 is undulatory in configuration, and because the effective length thereof is in register with the opening 22, that fusible element will be able to yield, rather than break, when a force is applied to the top thereof. Thus, as indicated by FIGS. 7 and 8, the fusible element 36 can respond to a force, which dents the outer layer 78, to move further into the opening 22 rather than to break. The overall result is that the electric fuse 70 of FIGS. 5-8 can safely be used as an open fuse, and can be embedded within the winding of an electromagnetic coil.
  • An electric fuse that comprises:
  • an insulating support which has an opening therein and which has aligning notches therein;
  • said contact areas being spaced apart by said opening
  • said fusible element having reverse bends therein which give said'fusible element an undulatory configuration.
  • An electric fuse as claimed in claim 1 wherein said opening is disposed inwardly of all portions of the periphery of said insulating support, and wherein said portions of the periphery of said insulating support protect said fusible element by hold ing all objects away from the sides of said fusible element.
  • An electric fuse that comprises:
  • an insulating support which has an opening therein and which has portions that define and that extend outwardly from said opening; I contact areas on said insulating support intermediate said opening and the periphery of said insulating support;
  • said contact areas being spaced apart by said opening
  • said fusible element having reverse bends therein which give said fusible element an undulatory configuration
  • said opening in said support and said undulatory configuration of said fusible element enabling said fusible element to respond to a force applied to the top of said fusible element to move into said opening rather than to break.
  • connecting elements have the inner ends thereof overlying, and electrically bonded and mechanically secured to, said contact areas, and wherein said connecting elements have the outer ends thereof extending outwardly from and beyond said contact areas.
  • An electric fuse that comprises:
  • an insulating support which has an elongated, centrally located opening therein and which has aligning notches in the ends thereof;
  • said contact areas being spaced apart by said centrally located opening
  • a fusible element that spans said centrally located opening and that has the ends thereof overlying said contact areas and extending into said alignment notches and bent under the bottom surface of said insulating support;
  • connecting elements having'the inner ends thereof overlying said contact areas and having the outer ends thereof extending outwardly beyond said ends of said support;
  • said alignment notches defining a line which extends longitudinally of said support and of said centrally located opening;
  • said fusible element having reverse bends therein to give said fusible element an undulatoryiconfiguration.
  • the method of making a support-type fuse which comprises forming a thin fusible element so it has an undulatory configuration, forming a support so it has an opening therein and so it has generally V-shaped notches in the ends thereof and so it has contact areas on said ends thereof, moving said fusible element into register with aline between said generally V-shaped notches, moving the ends of said fusible element downwardly into said generally V-shaped notches to move a portion of said fusible element into register with said opening in said support and to move further portions of said fusible element into engagement with said contact areas, said generally V-shaped notches enabling the first said portion of said fusible element to be moved into register with .said opening and enabling said further portions of said fusible element to be moved into engagement with said contact areas without necessitating the use of forces which could elongate or distort said fusible element, and electrically bonding and mechanically securing the ends of said fusible element to said contact areas.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Fuses (AREA)

Abstract

The fragile fusible element of a low amperage electric fuse is protected by being mounted adjacent a longitudinally extending central opening within a support and by being made so it is undulatory in configuration.

Description

United States Patent 1111 3,568,122
[72] Inventor Angelo Urani [56] References Cited Louis, UNITED STATES PATENTS m1 APPLNQ 8644572 2,727,109 12/1955 VonHoorn 337/166 [221 PM 2,828,390 3/1958 McAlister 337/232 [45] Patented Mar.2, 1971 3,246,105 4/1966 Uram 337/183 [73] Assrgnee McGraw-Edlson Company E| i Primary Examiner-G. Harris [54] PROTECTOR FOR ELECTRIC CIRCUITS Assistant Examiner-F. E. Bell Attorney-Kingsland, Rogers, Ezell, Eilers & Robbins ABSTRACT: The fragile fusible element of a low amperage electric fuse is protected by being mounted adjacent a longitudinally extending central opening within a support and by being made so it is undulatory in configuration.
PROTECTOR FOR ELECTRIC CIRCUITS This invention relates to improvements in Protectors For Electric Circuits. More particularly, this invention relates to improvements in low amperage electric fuses.
It is, therefore, an object of the present invention to provide an improved low amperage electric fuse.
The fusible elements that are used in low amperage electric fuses have such small diameters that those fusible elements tend to be quite fragile. As a result, those fusible elements should be protected against injury during the manufacture, shipment and use of the low amperage electric fuses of which they are component parts. The fusible element of the present invention is protected against injury, during the manufacture, shipment and use of the low amperage electric fuse of which it is a component part, by being mounted adjacent a longitudinally extending central opening within a support and by being made so it is undulatory in configuration. The portions of that support which define, and which extend outwardly from, that central opening tend to protect that fusible element by holding objects away from the sides of that fusible element; and the undulatory configuration of that fusible element tends to protect that fusible element by permitting that fusible element to yield if any object engages the top of that fusible element. As a result, the fusible element of the present invention is resistant to injury,.during the manufacture, shipment and use of the low amperage electric fuse of which it is a component part. It is, therefore, an object of the present invention to provide a low amperage electric fuse which has the fusible element thereof of undulatory configuration and mounted adjacent a longitudinally extending central opening within a support.
Because the fusible elements of low amperage electric fuses have very small diameters, the unit-lengthresistances of those fusible elements are relatively high; and hence it is important to fix the effective lengths of those fusible elements. The present invention fixes the effective length of the fusible element of the low amperage electric fuse thereof by forming precisely spaced contact areas at the ends of the longitudinally extending opening in the support for that fusible element and by forming notches in the ends of that support to fix the positions of the ends of that fusible element relative to those contact areas. The sides of the notches in the ends of the support for the fusible element are inclined relative to each other to make those notches generally V-shaped in configuration; and
those notches enable moderate forces, applied to the ends of the fusible element, to guide those ends into predetermined positions relative to the contact areas on that support. The use of such moderate forces is important, because such forces will not stretch or distort the fusible element. The overall result is that the effective length of the fusible element of the low amperage electric fuse of the present invention can be easily and accurately fixed. It is, therefore, an object of the present invention to provide a support, for the fusible element of an electric fuse, which has precisely shaped contact areas. at the ends of a longitudinally extending opening therein and which has generally V-shaped notches in the ends thereof to enable moderate fuses to guide the ends of that fusible element into predetermined positions relative to those contact areas.
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 two preferred embodiments of the present invention are 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 an enlarged, longitudinal, sectional view through one preferred embodiment of low amperage electric fuse that is made in accordance with the principles and teachings of the present invention;
FIG. 2 is an enlarged, longitudinal, sectional view which is similar to that of FIG. 1 but wherein the electric fuse has been rotated about the longitudinally extending axis thereof:
FIG. 3 is a sectional view, on a still large scale, through the electric fuse of FIG. 1, and it is taken along the plane indicated by the lines 3-3 in FIG. 1;
FIG. 4 is a sectional view, on the scale of FIG. 3, through the electric fuse of FIG. 1, and it is taken along the plane indicated by the line 44 in FIG. 3;
FIG. 5 is a perspective view of a second preferred embodiment of low amperage electric fuse that is made in accordance with the principles and teachings of the present invention;
FIG. 6 is a broken-away, elevational view of an electromagnetic coil in which the electric fuse of FIG. 5 is embedded;
FIG. 7 is a sectional view, on a larger scale, through the electric fuse of FIG. 5, and it is taken along the plane indicated by the line 77 in FIG. 6; and
FIG. 8 is a sectional view which is similar to that shown in FIG. 7 but wherein part of the insulation for the electromagnetic coil has engaged and moved part of-the fusible element.
Referring to the drawing in detail, the numeral 20 denotes a support which is made from an insulating material which can withstand the temperatures used in soldering, which can have an opening and notches formed therein by a punching operation, and which is dimensionally stable. While different materials could be used in making the support 20, phenolic resins have been found to be very useful. The numeral 22 denotes a longitudinally directed, rectangular opening in the support 20, As emphasized by FIGS. 1 and 2, that opening is spaced inwardly from each side of the support 20, and also is spaced inwardly from each end of that support. In actual practice, the geometric center of the opening 22 is coincident with the geometric center of the support 20. The numeral 24 denotes the V-shaped entrance of an aligning notch 26 in the left-hand end of the support 20; and the geometric centers of the notch and of that V-shaped entrance lie on the longitudinally directed center line of that support. The numeral 28 denotes the V-shaped entrance of an aligning notch 30 in the right-hand end of the support 20; and the geometric centers of that notch and of that V-shaped entrance lie on the l0ngitudinally directed center line of that support.
The numeral 32 denotes a contact area which overlies the upper surface of the left-hand end of the support 20; and that contact area is made from a metal with which solder can readily alloy. The right-hand edge of the contact area 32 terminates adjacent the left-hand end of the opening 22 in the support 20. The numeral 34 denotes a contact area which overlies the upper surface of the right-hand end of the support 20; and that contact area is made from a metal with which solder can readily alloy. The left-hand edge of the contact area 34 terminates adjacent the right-hand end of the opening 22. Because the opening 22 will preferably be formed by a punching operation, and thus may have minute burrs or projections at the ends thereof, the confronting edges of the contact areas 32 and 34 are spaced outwardly from the ends of the opening 22. The V- shaped entrances 24 and 28 and the notches 26 and 30 also will preferably be formed by a punching operation; and in actual practice, the opening 22, the V- shaped entrances 24 and 28, and the notches 26 and 30 are all punched at the same time.
The numeral 36 denotes a wirelike fusible element of small diameter; and that diameter will vary with the ampere rating of the electric fuse. However, in all cases, the diameter of that fusible element will be very much smaller than that shown in FIGS. 1-4. The numeral 38 denotes a portion of the fusible element 36 which has been bent downwardly through the notch 26 and then bent into engagement with the bottom surface of the support 20. The numeral 40 denotes a portion of the fusible element 36 which has been bent downwardly through the notch 30 and then bent into engagement with the support 20. The fusible element 36 has a series of reverse bends therein; and those bends provide an undulatory configuration for that fusible element.
Where the electric fuse provided by the present invention is to be assembled by hand, the V- shaped entrances 24 and 28 and the notches 26 and 30 will enable the assembler to use only moderate forces in guiding the ends of the fusible element 36 into registry with the longitudinally directed center line of the support 20. The use of moderate forces is important, because such forces will not stretch or distort that fusible element. The V-shaped entrances 24 and 28' and the notches 26 and 30 will, after the portions 38 and 40 of the fusible element 36 have been bent downwardly through the notches 26 and 30 and then into engagement with the bottom surface of the support 20, help hold that fusible element in registry with the longitudinally directed center line of that support. Where the electric fuse provided by the present invention is to be assembled by a machine, the V- shaped entrances 24 and 28 and the notches 26 and'30 again will enable moderate forces to be used in guiding the ends of the fusible element 36 into registry with the longitudinally directed center line of the support 20. The V- shaped entrances 24 and 28 and the notches 26 and 30 will, after the portions 38 and 40 of the fusible element 36 have been bent downwardly through the notches 26 and 30 and then into engagement with the bottom surface of the support 20, help hold that fusible element in registry with the longitudinally directed center line of that support.
The contact area 32 and the contact area 34 can be made in different ways. One preferred way of making those contact areas is to form spaced layers of copper on the upper surface of the support 20, and then form coatings of tin on those spaced layers of copper. When made in that way, the contact areas 32 and 34 will have upper surfaces with which solder can readily alloy.
The numeral 42 denotes solder which bonds the left-hand end of the fusible element 36 to the contact area 32 and the numeral 43 denotes solder which bonds the right-hand end of that fusible element to the contact area 34. The solder 42 and 43 will not only electrically bond, but also will mechanically secure, the fusible element 36 to the contact areas 32 and 34.
The numeral 46 denotes a wirelike connecting element which is made from a metal having a low resistivity and a relatively high degree of ductility. The inner end of the connecting element 46 overlies a portion of the contact area 32 and is electrically bonded, and mechanically secured, to that contact area by solder 48. The numeral 50 denotes a wirelike connecting element which is similar to the connecting element 46. The inner end of the connecting element 50 overlies a portion of the contact area 34 and is electrically bonded, and mechanically secured, to that contact area 34 by solder 52. While the connecting elements 46 and 50 could be made of different metals, copper has been found to be very useful.
While the solder 42 is shown as being separate and discrete from the solder 48, the solder 48 merges with and becomes almost indistinguishable from the solder 42. Similarly, while the solder 43 is shown as being separate and discrete from the solder 52, the solder 52 merges with and becomes almost indistinguishable from the solder 43. In applying the solder 42 and the solder 48 to the contact area 32, the source of heat for the soldering operation will be spaced from the left-hand end of the fusible element 36 so that source of heat will not interfere with the positioning of that fusible element in register with the longitudinally directed center line of the support 20. Similarly, in applying the solder 43 and the solder 52 to the contact area 34, the source of heat for the soldering operation will be spaced from the right-hand end of the fusible element 36 so that source of heat will not interfere with the positioning of that fusible element in register with the longitudinally directed center line of the support 20.
The numeral 54 denotes a tubular casing of insulating material for the electric fuse of the present invention; and the inner diameter of that casing is large enough to permit the support 20 to be telescoped freely within thatcasing. As shown by FIGS. 1 and 2, the casing 54 is considerably longer than the support 20; and that support has the ends thereof spaced inwardly from the opposite ends of that casing. While the casing a 54 can be made of different materials, glass has been found to be very useful.
The outer end of the connecting element 46 is bent around the left-hand end of the casing 54, and then is bent into engagement with a portion of the outer surface of that casing. Similarly, the outer end of the connecting element 50 is bent around the right-hand end of the casing 54, and then is bent into engagement with a portion of the outer surface of that casing. The numeral 56 denotes a ferrulelike terminal; and the inner diameter of that terminal is large enough to enable that terminal to be telescoped over the left-hand end of the casing -54 and over the bent outer end of the connecting element 46.
The numeral 58 denotes a mass of solder which electrically bonds the connecting element 46 to the terminal 56.
The numeral 62 denotes a ferrulelike terminal which is similar to the ferrulelike terminal 56. The inner diameter of the terminal 62 is large enough to enable that terminal to be telescoped over the right-hand end of the casing 54 and over the bent outer end of the connecting element 50. The numeral 64 denotes a mass of solder which electrically bonds the connecting element 50 to the terminal 62.
In fabricating the electric fuse provided by .the present invention, the contact areas 32 and 34 are formed on the opposite ends of the upper surface of the support 20. Thereafter, the opening 22, the V-shaped entrances 24 and 28, and the notches 26 and 30 are formed by a punching operation. While the punch and die that are used in forming the opening 22, the V-shaped entrances 24 and 28, and the notches 26 and 30 will be designed to leave the ends of the opening 22 as free from burrs and rough sports as possible, some burrs and some rough spots will be formed at those ends. However, those burrs and rough spots will have heights less than the thicknesses of the contact areas 32 and 34; and hence those contact areas will space the portions of the fusible element 36, which are in register with the ends of the opening 22, away from those ends. This means that burrs and rough spots on the ends of the opening 22 will be unable to cut or otherwise impair the fusible element 36 as that fusible element is assembled with the support 20. At the time the opening 22, the V-shaped entrances 24 and 28, and the notches 26 and 30 are punched, or at some subsequent time, the ampere rating of the electric fuse will be stamped into the bottom surface of the support 20. In the preferred embodiment of electric fuse shown by FIGS. 1-4, the ampere rating is 1 A, and hence a l and a /4 are stamped into the bottom surface of the support 20.
In assembling the fusible element 36 with the support 20, that fusible element will be gripped by the assembler, or by the machine which is used in fabricating the electric fuse; and then the ends of that fusible 1 element will be moved downwardly toward the support 20. The V-shaped entrances 24 and 28 will automatically guide the ends of the fusible element 36 into register with the notches 26 and 30, and hence will automatically guide that fusible element into position wherein it is generally parallel to the longitudinally directed center line of that support. The curved inner ends of the notches 26 and 30 will help guide the ends of the fusible element 36 into registry with that longitudinally directed center line; and then the assembler, or the machine which is used in fabricating the electric fuse, will bend the ends of that fusible element downwardly through the notches 26 and 30 into engagement with the bottom surface of the support 20. Once the ends of the fusible element 36 have been bent into engagement with that bottom surface, any excess lengths of those ends can be cut away; and, thereafter, no further handling of the fusible element 36 will be required. This is desirable, because it minimizes the risk of breaking or fatiguing that small diameter, inherently fragile, fusible element.
The connecting elements 46 and 50 will then be disposed so the confronting ends thereof overlie the contact areas 32 and 34; and then the solder 42, 43, 48 and 52 will be applied to those contact areas to electrically bond, and mechanically secure, those connecting elements and the fusible element 36 to those contact areas. The solder 42 will flow up to, but will stop at, the right-hand edge of the contact area 32; and the solder 43 will flow up to, but will stop at, the left-handedge of the contact area 34. Theportion of the fusible element 36 which is disposed between the confronting edges of the contact areas 32 and 34 is the effective length of that fusible element; and that effective length will be fixed by the precise spacing between the confronting edges of the contact areas 32 and 34 and by the positioning of that fusible element so it is generally parallel to the longitudinally directed center line of the support 20.
Referring particularly to FIGS. 5 8, the numeral 70 generally denotes a second embodiment of electric fuse that is made in accordance with the principles and teachings of the present invention. That second embodiment can be identical with the embodiment shown in FIGS. 1-4, except for the fact that it isnot enclosed within a casing such as the casing 54. In
stead,-the electric fuse 70 will be directly embedded within an of turns thereof; .and two of those layers are denoted by the numerals 74 and 76. In addition, the coil 72 has an outer layer 78 of insulation. While the layers 74, 76 and 78 of insulation are shown by FIGS. 7 and 8 as being spaced apart, those layers will usuallybe parts of one continuous strip of insulation. The connecting elements 46 and 50 .of the electric fuse 70 of FlGS.5-8 are connected to portions of the terminal 80 of the coil 72, and thus are connected in series with that terminal, with the coil 72, and with the terminal 82. in the event that coil is subjected to a potentially hurtful overload, the fusible element 36 will fuse and thereby prevent an electrical fire.
As shown by FIGS. 7 and 8, the bottom surface of the support will be disposed against the layer 76, and then the outer layer 78 will be placed adjacent the upper surface of that support. That outer layer may bear against the upper surface of the fusible element 36, but the reverse bends in that fusible element will space many portions of that fusible element away from that outer layer. This is desirable; because it will keep the outer layer 78 from absorbing undue amounts of heat from those portions of the fusible element 36.
The portions of the support 20 which define, and which extend outwardly from, the central opening 22 will tend to protect the fusible element 36 by holding objects away from the sides of that fusible element. As a result, the sides of that fusible element are protected from injury while the electric fuse 70 is being manufactured, shipped and used. Because the fusible element 36 is undulatory in configuration, and because the effective length thereof is in register with the opening 22, that fusible element will be able to yield, rather than break, when a force is applied to the top thereof. Thus, as indicated by FIGS. 7 and 8, the fusible element 36 can respond to a force, which dents the outer layer 78, to move further into the opening 22 rather than to break. The overall result is that the electric fuse 70 of FIGS. 5-8 can safely be used as an open fuse, and can be embedded within the winding of an electromagnetic coil.
Whereas the drawing and accompanying description have shown and described two preferred embodiments 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 fuse without affecting the scope thereof.
I claim:
1. An electric fuse that comprises:
an insulating support which has an opening therein and which has aligning notches therein;
contact areas on said insulating support intermediate said opening and said aligning notches;
said contact areas being spaced apart by said opening;
a fusible element that spans said opening and that has the ends thereof overlying said contact areas and extending into said alignment notches;
solder electrically bonding, and mechanically securing, said ends of said fusible element to said contact areas; and
said fusible element having reverse bends therein which give said'fusible element an undulatory configuration.
2. An electric fuse as claimed in claim 1 wherein the confronting edges of said contact areas are spaced outwardly of the adjacent edges of said opening, and thus are spaced outwardly of any burrs and rough spots on said adjacent edges of said opening.
3. An electric fuse as claimed in claim 1 wherein said opening is disposed inwardly of all portions of the periphery of said insulating support, and wherein said portions of the periphery of said insulating support protect said fusible element by hold ing all objects away from the sides of said fusible element.
4. An electric fuse as claimed in claim 1 wherein some of said reverse bends in said fusible element are disposed within said opening, and wherein said opening and the reverse bends in said fusible element coact to enable said fusible element to move inwardly of said opening, rather than to break, in response to the application of a force to the top of said fusible element.
5. An electric fuse as claimed in claim 1 wherein said opening is rectangular in configuration and wherein said fusible element is parallel to the long axis of said opening.
6. An electric fuse as claimed in claim 1 wherein said aligning notches have generally V-shaped entrances and arcuate inner ends.
7. An electric fuse as claimed in claim 1 wherein said ends of said fusible element are bent downwardly to extend through said aligning notches and are then bent to engage the bottom surface of said insulating support.
8. An electric fuse that comprises:
an insulating support which has an opening therein and which has portions that define and that extend outwardly from said opening; I contact areas on said insulating support intermediate said opening and the periphery of said insulating support;
said contact areas being spaced apart by said opening;
a fusible element that spans said opening and that has portions thereof overlying said contact areas;
solder electrically bonding, and mechanically securing, said portions of said fusible element to said contact areas;
said fusible element having reverse bends therein which give said fusible element an undulatory configuration;
said portions of said insulating support that define and that extend outwardly from said opening protecting said fusible element by spacing objects away from the sides of said fusible element; and
said opening in said support and said undulatory configuration of said fusible element enabling said fusible element to respond to a force applied to the top of said fusible element to move into said opening rather than to break.
9. An electric fuse as claimed in claim 8 wherein the confronting edges of said contact areas are spaced outwardly of the adjacent edges of said opening, and thus are spaced outwardly of any burrs and rough spots on said adjacent edges of said opening.
10. An electric fuse as claimed in claim 8 wherein some of said reverse bends in said fusible element are disposed within said opening and wherein other of said reverse bends are disposed above said opening.
11. An electric fuse as claimed in claim 8 wherein said contact areas space said portions of said fusible element above the upper surface of said insulating support and thereby space said portions of said fusible element above burrs and rough spots on the adjacent edges of said opening.
12. An electric fuse as claimed in claim 8 wherein said opening is rectangular in configuration and wherein said fusible element is parallel to the long axis of said opening.
13. An electric fuse as claimed in claim 8 wherein connecting elements have the inner ends thereof overlying, and electrically bonded and mechanically secured to, said contact areas, and wherein said connecting elements have the outer ends thereof extending outwardly from and beyond said contact areas.
14. An electric fuse that comprises:
an insulating support which has an elongated, centrally located opening therein and which has aligning notches in the ends thereof;
contact areas on said support intermediate the ends of said centrally located opening and said aligning notches;
said contact areas being spaced apart by said centrally located opening;
a fusible element that spans said centrally located opening and that has the ends thereof overlying said contact areas and extending into said alignment notches and bent under the bottom surface of said insulating support;
connecting elements having'the inner ends thereof overlying said contact areas and having the outer ends thereof extending outwardly beyond said ends of said support;
solder electrically bonding and mechanically securing said ends of said fusible element and said inner ends of said connecting elements to said contact areas;
said alignment notches defining a line which extends longitudinally of said support and of said centrally located opening; and
said fusible element having reverse bends therein to give said fusible element an undulatoryiconfiguration.
15. The method of making a support-type fuse which comprises forming a thin fusible element so it has an undulatory configuration, forming a support so it has an opening therein and so it has generally V-shaped notches in the ends thereof and so it has contact areas on said ends thereof, moving said fusible element into register with aline between said generally V-shaped notches, moving the ends of said fusible element downwardly into said generally V-shaped notches to move a portion of said fusible element into register with said opening in said support and to move further portions of said fusible element into engagement with said contact areas, said generally V-shaped notches enabling the first said portion of said fusible element to be moved into register with .said opening and enabling said further portions of said fusible element to be moved into engagement with said contact areas without necessitating the use of forces which could elongate or distort said fusible element, and electrically bonding and mechanically securing the ends of said fusible element to said contact areas.

Claims (15)

1. An electric fuse that comprises: an insulating support which has an opening therein and which has aligning notches therein; contact areas on said insulating support intermediate said opening and said aligning notches; said contact areas being spaced apart by said opening; a fusible element that spans said opening and that has the ends thereof overlying said contact areas and extending into said alignment notches; solder electrically bonding, and mechanically securing, said ends of said fusible element to said contact areas; and said fusible element having reverse bends therein which give said fusible element an undulatory configuration.
2. An electric fuse as claimed in claim 1 wherein the confronting edges of said contact areas are spaced outwardly of the adjacent edges of said opening, and thus are spaced outwardly of any burrs and rough spots on said adjacent edges of said opening.
3. An electric fuse as claimed in claim 1 wherein said opening is disposed inwardly of all portions of the periphery of said insulating support, and wherein said portions of the periphery of said insulating support protect said fusible element by holding all objects away from the sides of said fusible element.
4. An electric fuse as claimed in claim 1 wherein some of said reverse bends in said fusible element are disposed within said opening, and wherein said opening and the reverse bends in said fusible element coact to enable said fusible element to move inwardly of said opening, rather than to break, in response to the application of a force to the top of said fusible element.
5. An electric fuse as claimed in claim 1 wherein said opening is rectangular in configuration and wherein said fusible element is parallel to the long axis of said opening.
6. An electric fuse as claimed in claim 1 wherein said aligning notches have generally V-shaped entrances and arcuate inner ends.
7. An electric fuse as claimed in claim 1 wherein said ends of said fusible element are bent downwardly to extend through said aligning notches and are then bent to engage the bottom surface of said insulating support.
8. An electric fuse that comprises: an insulating support which has an opening therein and which has portions that define and that extend outwardly from said opening; contact areas on said insulating suppOrt intermediate said opening and the periphery of said insulating support; said contact areas being spaced apart by said opening; a fusible element that spans said opening and that has portions thereof overlying said contact areas; solder electrically bonding, and mechanically securing, said portions of said fusible element to said contact areas; said fusible element having reverse bends therein which give said fusible element an undulatory configuration; said portions of said insulating support that define and that extend outwardly from said opening protecting said fusible element by spacing objects away from the sides of said fusible element; and said opening in said support and said undulatory configuration of said fusible element enabling said fusible element to respond to a force applied to the top of said fusible element to move into said opening rather than to break.
9. An electric fuse as claimed in claim 8 wherein the confronting edges of said contact areas are spaced outwardly of the adjacent edges of said opening, and thus are spaced outwardly of any burrs and rough spots on said adjacent edges of said opening.
10. An electric fuse as claimed in claim 8 wherein some of said reverse bends in said fusible element are disposed within said opening and wherein other of said reverse bends are disposed above said opening.
11. An electric fuse as claimed in claim 8 wherein said contact areas space said portions of said fusible element above the upper surface of said insulating support and thereby space said portions of said fusible element above burrs and rough spots on the adjacent edges of said opening.
12. An electric fuse as claimed in claim 8 wherein said opening is rectangular in configuration and wherein said fusible element is parallel to the long axis of said opening.
13. An electric fuse as claimed in claim 8 wherein connecting elements have the inner ends thereof overlying, and electrically bonded and mechanically secured to, said contact areas, and wherein said connecting elements have the outer ends thereof extending outwardly from and beyond said contact areas.
14. An electric fuse that comprises: an insulating support which has an elongated, centrally located opening therein and which has aligning notches in the ends thereof; contact areas on said support intermediate the ends of said centrally located opening and said aligning notches; said contact areas being spaced apart by said centrally located opening; a fusible element that spans said centrally located opening and that has the ends thereof overlying said contact areas and extending into said alignment notches and bent under the bottom surface of said insulating support; connecting elements having the inner ends thereof overlying said contact areas and having the outer ends thereof extending outwardly beyond said ends of said support; solder electrically bonding and mechanically securing said ends of said fusible element and said inner ends of said connecting elements to said contact areas; said alignment notches defining a line which extends longitudinally of said support and of said centrally located opening; and said fusible element having reverse bends therein to give said fusible element an undulatory configuration.
15. The method of making a support-type fuse which comprises forming a thin fusible element so it has an undulatory configuration, forming a support so it has an opening therein and so it has generally V-shaped notches in the ends thereof and so it has contact areas on said ends thereof, moving said fusible element into register with a line between said generally V-shaped notches, moving the ends of said fusible element downwardly into said generally V-shaped notches to move a portion of said fusible element into register with said opening in said support and to move further portions of said fusible element into engagement with said contact areas, said generally V-shaped notches enabling the fIrst said portion of said fusible element to be moved into register with said opening and enabling said further portions of said fusible element to be moved into engagement with said contact areas without necessitating the use of forces which could elongate or distort said fusible element, and electrically bonding and mechanically securing the ends of said fusible element to said contact areas.
US864672A 1969-10-08 1969-10-08 Protector for electric circuits Expired - Lifetime US3568122A (en)

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3875542A (en) * 1971-02-10 1975-04-01 Tektronix Inc High frequency fuse
US3913051A (en) * 1974-05-22 1975-10-14 Mc Graw Edison Co Protector for electric circuits
EP0030157A1 (en) * 1979-12-03 1981-06-10 Dubilier plc Electrical cartridge fuselinks and method of manufacturing such fuselinks
US4414528A (en) * 1980-03-24 1983-11-08 Bel Fuse, Inc. Crimp fuse
DE3401368A1 (en) * 1984-01-17 1985-10-03 AEG-Telefunken Kabelwerke AG, Rheydt, 4050 Mönchengladbach Electrical melting fuse element
US4929921A (en) * 1989-03-16 1990-05-29 Cooper Industries, Inc. Automatable fuse
NL9100617A (en) * 1990-05-10 1991-12-02 Soc Corp CHIP MELTING SAFETY WITH VARIABLE TIME FLOW CHARACTERISTICS.
US6665415B1 (en) * 1999-09-09 2003-12-16 Harman International Industries, Incorporated Loudspeaker overcurrent protection
US20050083167A1 (en) * 1999-04-29 2005-04-21 Cooper Technologies Company Fuse with fuse link coating
US20080297301A1 (en) * 2007-06-04 2008-12-04 Littelfuse, Inc. High voltage fuse

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US2727109A (en) * 1953-01-19 1955-12-13 Gen Electric Time lag fuse link
US2828390A (en) * 1953-09-24 1958-03-25 Mc Graw Edison Co Protectors for electric circuits
US3246105A (en) * 1963-02-06 1966-04-12 Mc Graw Edison Co Protector for electric circuits

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2727109A (en) * 1953-01-19 1955-12-13 Gen Electric Time lag fuse link
US2828390A (en) * 1953-09-24 1958-03-25 Mc Graw Edison Co Protectors for electric circuits
US3246105A (en) * 1963-02-06 1966-04-12 Mc Graw Edison Co Protector for electric circuits

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3875542A (en) * 1971-02-10 1975-04-01 Tektronix Inc High frequency fuse
US3913051A (en) * 1974-05-22 1975-10-14 Mc Graw Edison Co Protector for electric circuits
EP0030157A1 (en) * 1979-12-03 1981-06-10 Dubilier plc Electrical cartridge fuselinks and method of manufacturing such fuselinks
US4414528A (en) * 1980-03-24 1983-11-08 Bel Fuse, Inc. Crimp fuse
DE3401368A1 (en) * 1984-01-17 1985-10-03 AEG-Telefunken Kabelwerke AG, Rheydt, 4050 Mönchengladbach Electrical melting fuse element
US4929921A (en) * 1989-03-16 1990-05-29 Cooper Industries, Inc. Automatable fuse
NL9100617A (en) * 1990-05-10 1991-12-02 Soc Corp CHIP MELTING SAFETY WITH VARIABLE TIME FLOW CHARACTERISTICS.
US20050083167A1 (en) * 1999-04-29 2005-04-21 Cooper Technologies Company Fuse with fuse link coating
US6903649B2 (en) * 1999-04-29 2005-06-07 Cooper Technologies Company Fuse with fuse link coating
US6665415B1 (en) * 1999-09-09 2003-12-16 Harman International Industries, Incorporated Loudspeaker overcurrent protection
US20080297301A1 (en) * 2007-06-04 2008-12-04 Littelfuse, Inc. High voltage fuse

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