US2966649A - Fuse resistor - Google Patents

Description

Dec. 27, 1960 HAYNMAN 2,966,649

FUSE RESISTOR Filed Nov. 5, 1958 INVENTOR. ALEXANDRE HAYNMAN BY W/f%/ ATTO RNE Y FUSE RESISTOR Alexandre Haynman, Copenhagen-Vanlosa, Denmark,

assignor to International Resistance Company, Philadelphia, Pa., a corporation of Delaware Filed Nov. 3, 1958, Ser. No. 771,533

14 Claims. (Cl. 338-322) This invention relates to the construction of a fuse resistor, and more particularly, to an improved construction for a resistor having a fusible connection between the resistor element and a terminal therefor.

In many electrical circuits, it is often desirable to have a resistor which when heated to a predetermined temperature because of an electrical overload on the resistor, will electrically open up and thereby discontinue the flow of current through the circuit to protect the other components in the circuit. Resistors heretofore used for this purpose comprise either a wire wound resistor element which is constructed to burn out at the predetermined temperature or a resistor including a fusible link which melts at the predetermined temperature to open the resistor. However, such fuse resistors heretofore available have the disadvantages that they are complicated in construction so that they are difiicult and expensive to manufacture, and, more importantly, once they open up they cannot be reused but must be replaced with another resistor.

it is therefore an object of this invention to provide a novel construction of a fuse resistor.

It is another object of this invention to provide a novel construction of a fuse resistor which includes a fusible link which melts at a predetermined temperature to open the resistor.

It is still another object of this invention to provide a novel construction of a fuse resistor which can be applied to any desired type of resistor element.

It is another object of this invention to provide a novel construction of a fuse resistor which permits the resistor to be reused once it has opened up.

It is still a further object of this invention to provide a fuse resistor which is simple in construction so as to be easily and inexpensively manufactured.

Other objects of this invention will appear hereinafter.

For the purpose of illustrating the invention there is shown in. the drawings forms which are presently pre ferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

Figure l is a longitudinal elevational view of one embodiment of the fuse resistor of this invention.

Figure 2 is an end elevational view of the embodiment of the fuse resistor of this invention shown in Figure 1.

Figure 3 is an exploded perspective view of the embodiment of the fuse resistor of this invention shown in Figure 1.

Figure 4 is a longitudinal elevational view of another embodiment of the fuse resistor of this invention.

Figure 5 is an end elevational view of the embodiment of the fuse resistor of this invention shown in Figure 4.

Figure 6 is an exploded perspective view of the embodiment of the fuse resistor of this invention shown inFigure 4.

atent O Figure 7 is a perspective view of still another embodiment of the fuse resistor of the present invention.

Figure 8 is a sectional view taken along line 88. of Figure 7.

Referring to the drawings, Figures 1, 2, and 3 show one embodiment of the fuse resistor of this invention, generally designated by 10. Fuse resistor 10 comprises an electrical resistor element 12 having a pair of conductive wire terminal leads 14 and 16 extending from the ends thereof. Resistor element 12 may be any one of the well known types of resistors; for example, (1) a core of insulating material having awire. of an elece trical resistance metal helically wound thereon and a jacket or casing of an electrical insulating material surrounding the core and wire, or (2) a core of insulating material having a film of an electrical resistance material, such as carbon or a metal, coated on the surface of the core, and a casing or jacket of an electrical insulating material surrounding the core and the film, or (3) a molded body of an electrical insulating plastic having particles of an electrical resistance material, such as carbon, dispersed therein, and a casing or jacket ofan electrical insulating material surrounding said molded body. No matter which of the well known types of electrical resistors is used for resistor element 12 the terminal leads 14 and 16 are electrically connected to the ends of the resistor. and extend through the protective, insulating casing or jacket. A band 13 of an electrically conductive metal fits tightly around resistor ele-.

ment 12. Band 18 has a pair of spaced, substantially parallel arms 2t] and 22 extending outwardly therefrom anda substantially U-shaped trough portion 24. between the arms 2t? and 22 with the open end of the U facingoutwardy. One of the terminal leads, such as lead 14, Is bent back over resistance element 12 and extends into trough 24. Trough 24 is filled with a fusible metal 26- (Figure 2), such as solder, which electrically and mechanically connects terminal lead 14 to band 18. Fusible metal 26 is of a composition which will melt at the predetermined temperature at which it is desired for the resistor to open. The particular composition of a solder which will melt at a desired temperature can be found in any well known handbook or catalog on solders. A terminal member 28 of an electrically conductive metal is secured to band 18 and extends beyond the end of. resistor element 12. Terminal member 28 can either be an integral part of band 18 or secured thereto such as by brazing or welding. Although terminal member 28 can be soldered to band 18, care should be taken to usea solder which will melt at a higher temperature than the melting temperature of fusible metal 26. Although terminal member 28 is shown extending from the same end of resistor element 12 as terminal lead 14 so that the fuse resistor 16} is terminated at each end thereof, terminal member 28 may extend radially from the fuse resistor 10 or from the same end as terminal lead 16. Also, although resistor element 12 is shown to be of circular cross-section with the terminal band 18 being of similar configuration, resistor element 12 can be of any 24 by the fusible metal 26. Thus the fuse resistor 10 can be manufactured easily and quickly so as to be relatively inexpensive.

In use, fuse resistor 10 is connected into the desired circuit through terminal lead 16 and terminal member 28. Thus resistor element 12 is connected in the circuit at one end through terminal lead 16 and at the other end through terminal lead 14, fusable metal 26, band 18, and terminal member 28. During normal operation of the circuit resistor element 12 will heat up slightly but not to the melting point of fusable metal 26. However, if the circuit becomes overloaded, resistor element 12 will become overheated and when it reaches the melting point temperature of fusable metal 26, the fusable metal 26 will melt and the terminal lead 14 through its own resiliency will spring out of trough 24 to open circuit the fuse resistor 10. This in turn cuts off the flow of current through the circuit and thereby protects the other components in the circuit from becoming damaged by the overload of current. When the cause of the overload in the circuit has been corrected, and it is desired to close the circuit, it is only necessary to press terminal lead 14 back into trough 24 and reconnect it to band 18 by additional fusable metal 26. Thus, it is not necessary to replace the fuse resistor 10, as must be done with previously available fuse resistors, but the fuse resistor of this invention can be reused over again.

Figures 4, 5, and 6 show another embodiment of the fuse resistor of this invention, generally designated as 30. Fuse resistor 30 comprises a body 32 of an electrical insulating material, such as a plastic or ceramic, having a pair of spaced holes 34 and 36 extending longitudinally therethrough slightly beneath the surface thereof. Body 32 is also shown to have a central longitudinally extending hole 38 which can be used for mounting the fuse resistor 30. A terminal lead 40 of an electrically conductive metal fits tightly into hole 34 and projects beyond body 32 from only one end thereof. A terminal lead 42 of an electrically conductive metal fits in hole 36 and projects beyond body 32 from both ends thereof. Body 32 is provided adjacent its end from which terminal lead 40 projects with a transverse slot 44 extending from the surface of body 32 to the hole 34 to expose a portion of terminal lead 40. A band 46 of an electrically conductive metal fits tightly around body 32 adjacent the other end of the body. Band 46 has a pair of spaced, substantially parallel arms 48 and 50 extending outwardly therefrom and a substantially U-shaped trough portion 52 between arms 48 and 50 with the open end of the U facing outwardly. A wire 54 of an electrical resistance metal is helically wound around and along body 32. At one end wire 54 extends across and into slot 44 and contacts terminal lead 40. Wire 54 may be welded or soldered to terminal lead 40 to insure good electrical contact thereto. The other end of wire 54 is connected to band 46 such as by welding, soldering, or the like. The portion 42a of terminal lead 42 which projects beyond the end of body 32 opposite the end of the body to which band 46 is secured is bent back over body 32 and extends into trough 52. Trough 52 is filled with a fusable metal 56, such as solder, to electrically and mechanically connect terminal lead 42 to band 46. If desired, body 32 and resistance wire 54 may be provided with a protective, electrical insulating coating or jacket, leaving portion 42a of terminal lead 42 and trough 52 exposed. Although body 32 is shown to be of elliptical cross-sectional configuration, it may be of any desired cross-sectional con figuration, such as rectangular, circular, or the like. Also, although the resistance material is shown to be a metal Wire, it can also be a film of a resistance material, such as carbon or a metal, coated on the surface of body 32 and extending into slot 44 to contact terminal lead 40 as well as contacting band 46. Fuse resistor 39 is used and operates in the same manner as fuse resistor 10 previously described.

Figure 7 shows still another embodiment of the fuse resistor of the present invention, generally designated as 58. Fuse resistor 58 comprises a body 60 of an electrical insulating material, such as a plastic or ceramic, having a pair of spaced holes 62 and 64 extending longitudinally therethrough slightly beneath the surface thereof, and a central longitudinally extending hole 66. A terminal lead 68 of an electrically conductive metal fits tightly into hole 62 and projects beyond one end of body 60. A wire member 70 of an electrically conductive metal fits into hole 64 and projects beyond the other end of body 60, with the projecting end of the wire member 70 being bent back over the outer surface of the body 60. Body 60 is provided adjacent its end from which terminal lead 68 projects with a transverse slot 72 extending from the surface of body 60 to the hole 62 to expose a portion of the terminal lead 68. Body 60 is also provided adjacent its end fro-m which wire member 70 projects with a transverse slot 74 extending from the surface of the body 60 to the hole 64 to expose a portion of the wire member 74 A wire 76 of an electrical resistance metal is helically wound around and along body 60. At one end wire 76 extends across and into slot 72 and contacts terminal lead 68. At the other end wire 76 extends across and into slot 74 and contacts wire member 70. Wire 76 may be welded or soldered to terminal lead 68 and wire member 70 to insure good electrical contact thereto. A second terminal lead 78 of an electrical conducting metal extends through central hole 66 and projects beyond both ends of the body 69. The end 78a of the second terminal lead 78 which projects from the same end of body 60 as the first terminal lead 68 is bent back over the outer surface of body 6-0 and extends over the end of wire member 70. As shown in Figure 8, the end of wire member 70 is provided with a substantially V-shaped trough portion into which the end 73a of second terminal lead 78 extends. Trough 80 is filled with a fusable metal 82, such as solder, to electrically and mechanically connect second terminal lead 78 to wire member 743.

If desired, body 60 and resistance wire 76 may be provided with a protective, electrical insulating coating or jacket, leaving the portions of terminal leads 68 and 78 and wire member 70 which project beyond body 60 exposed. Although body 60 is shown to be of elliptical cross-sectional configuration, it may be of any desired cross-sectional configuration, such as rectangular, circular, or the like. Also, although the resistance material is shown to be a metal wire, it can also be a film of a resistance material, such as carbon or a metal, coated on the surface of body 60 and extending into slots 72 and 74 to contact terminal lead 68 and wire member 70. Fuse resistor 58 is used and operates in the same manner as fuse resistor 10 previously described.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specificatio-n as indicating the scope of the invention.

I claim:

1. A fuse resistor comprising an electrical resistance element, a band of an electrically conductive metal secured around said resistance element, means electrically connecting one end of said resistance element to said band, a terminal member of electrically conductive metal, means connecting said terminal member to said band, one of said connecting means comprising a wire of electrically conductive metal bent back over and extending along said resistance element and releasably secured to said band by a fusable metal, and a terminal member of an electrically conductive metal secured to the other end of said resistance element.

2. The fuse resistor as set forth in claim 1 in which said band is provided with a substantially U-shaped trough, the open end of which faces outwardly away from the resistance element, and the connecting wire extends into said trough and is releasably secured therein by the fusable metal.

3. The fuse resistor as set forth in claim 1 in which said band is provided with a pair of spaced, substantially parallel arms extending outwardly therefrom and a substantially U-shaped trough portion between said arms with the open end of the U facing outwardly away from the resistance element, and the connecting wire extends into said trough and is releasably secured therein by the fusable metal.

4. A fuse resistor comprising a resistor element having an electrically conducting metal wire terminal lead extending from each end thereof, a band of electrically conducting metal secured around said resistor element, one of said terminal leads being bent back over and extending along said resistor element and releasably secured to said band by a fusable metal, and a terminal member secured to said band and extending beyond said resistor element.

5. A fuse resistor as set forth in claim 4 in which said band is provided with a substantially U-shaped trough, the open end of which faces outwardly away from the resistor element and the terminal lead extends into said trough and is releasably secured therein by the fusable metal.

6. A fuse resistor as set forth in claim 4 in which said band is provided with a pair of spaced, substantially parallel arms extending outwardly therefrom and a substantially U-shaped trough portion between said arms with the open end of the U facing outwardly away from the resistor element, and the terminal lead extends into said trough and is releasably secured therein by the fusable metal.

7. A fuse resistor comprising a body of electrical insulating material having a pair of spaced holes extending longitudinally therethrough and slightly beneath the surface thereof, a first terminal member of electrically conducting metal fitting into one of said holes and projecting beyond one end of said body, a transverse slot in said body extending from the surface thereof to said one hole to expose a portion of said first terminal member, a second terminal member of electrically conducting metal fitting into said other hole and projecting beyond both ends of said body, a band of electrically conducting metal secured around said body, an electrical resistance material on the surface of said body, said resistance material at one end extending into said slot and electrically contacting said first terminal member and at the other end contacting said band, and one end of said second terminal member being bent back over said body and releasably secured to said band by a fusable metal.

8. The fuse resistor as set forth in claim 7 in which said slot is located adjacent the end of said body from which said first terminal member extends and the band is located adjacent the other end of said body.

9. The fuse resistor as set forth in claim 8 in which said band is provided with a substantially U-shaped trough, the open end of which faces outwardl away from said body and the one end of said second terminal member extends into said trough and is releasably secured therein by the fusable metal.

10. The fuse resistor as set forth in claim 8 in which said band is provided with a pair of spaced, substantially parallel arms extending outwardly therefrom and a substantially U-shaped trough portion between said arms with the open end of the U facing outwardly away from said body, and the one end of said second terminal member extends into said trough and is releasably secured therein by the fusable metal.

11. A fuse resistor comprising an electrical resistance element, a pair of terminal members of electrical conducting metal extending from said resistance element, one of said terminals being connected to one end of said resistance element, and means connecting the other terminal to the other end of said resistance element, said means including a substantially resilient member of electrical conductive metal extending from an end of said resistance element and bent back over and extending along said resistance element, and a junction of fusable metal at the end of said member over said resistance element.

12. A fuse resistor comprising a body of electrical insulating material having three spaced holes extending longitudinally therethrough, a first terminal member of electrically conductive metal fitting into one of said holes and projecting beyond an end of said body, a transverse slot in said body extending from the surface of said body to said one hole to expose a portion of said first terminal member, a member of electrically conductive metal fitting into a second of said holes and projecting beyond an end of said body, the projecting end of said metal member being bent back over the body, a second transverse slot in said body extending from the surface of said body to said second hole to expose a portion of said metal member, an electrical resistance material on the surface of said body, said resistance material extending into said slots and electrically contacting said first terminal member and said metal member, and a second terminal member of electrically conductive metal extending through the third hole and projecting beyond both ends of said body, one of the projecting ends of said second terminal member being bent back over said body and connected to the end of said metal member by a fusable metal.

13. The fuse resistor as set forth in claim 12 in which said first and second holes in said body are slightly beneath the surface of said body and the slots are longitudinally spaced from each other.

14. The fuse resistor as set forth in claim 12 in which the end of said metal member which is over the surface of the body has a substantially V-shaped trough portion and the end of said second terminal member which is connected to said metal member fits into said trough portion.

References Cited in the file of this patent UNITED STATES PATENTS 1,238,124 Frickey Aug. 28, 1917 FOREIGN PATENTS 931,560 France Feb. 26, 1948

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