Patent Publication Number: US-3878497-A

Title: Fuse link assembly suitable for use in automotive electrical system

Description:
United States Patent [1 1 Spangler [451 Apr. 15, 1975 FUSE LINK ASSEMBLY SUITABLE FOR USE IN AUTOMOTIVE ELECTRICAL SYSTEM [75] Inventor: Paul Joseph Spangler, Novelty, Ohio [73] Assignee: International Telephone and Telegraph Corp., New York, NY.  
 [22] Filed: Feb. 7, 1974 [21] Appl. No.: 440,349  
 [52] US. Cl. 337/295; 337/186; 337/197; 337/201; 337/228; 337/237; 337/246; 337/290 [51] Int. Cl. H0lh 85/08 [58] Field of Search 337/227, 228, 231, 234, 337/236, 237, 186, 187, 197, 198, 201, 246,  
 [56] References Cited UNITED STATES PATENTS 2/1946 Wiard 337/246 7/1955 Swain 337/246 X 6/1960 Sims et al. 337/187 FOREIGN PATENTS OR APPLICATIONS 364,719 11/1922 Germany 337/246 Primary ExaminerR. N. Envall, Jr. Attorney, Agent, or Firm-James B. Raden; William J. Michals [57] ABSTRACT 6 Claims, 9 Drawing Figures PATH-HEB APR 1 5 1975 saw 1 or 2 F|G.i (PRIOR ART) FIG.  
 FIG. 5  
 FIG.  
 PHH HEB AFR I 5 I875 sum a nr 2 FIG. 9  
 L .J J  
 FIG. 6  
 FIG. 7  
 FIG. 8  
 FUSE LINK ASSEMBLY SUITABLE FOR USE IN AUTOMOTIVE ELECTRICAL SYSTEM BACKGROUND OF THE INVENTION This invention relates to a fuse link assembly and, more particularly, to a self-locking fuse link assembly for fusing a conductor such as a conductor in an automotive electrical system.  
  Fuse link assemblies for fusing a conductor by means of an intermediate, smaller diameter conductor are known. For example, a presently known method for fusing a No.8 AWG copper wire conductor ofa 55 ampere automobile electrical system circuit utilizes a No. 12 AWG copper fuse wire of a given length. Each end of the fuse wire is provided with a contact and, in turn, enclosed within an insulated housing, thereby to provide a connector assembly thereat. The adjacent ends of the No. 8 wire are similarly provided with cooperating contacts and enclosed within suitable housings. The connector assemblies of the fuse wire are respectively coupled to the connector assemblies of the No. 8 wire and a fused conductor is thusly provided. This method, however, has several known disadvantages. For example, four separate housings and contacts are required in addition to the fuse wire. Further, substantial labor is required to crimp a total of four contact joints, and to assemble four separate housings. Still further, these prior art devices necessitate using a high-temperature insulation over the fuse wire as the melting temperature of copper is approximately l900 F. Moreover, it has been found that even a high-temperature insulation is not always satisfactory; that is, when the hightemperature insulation does melt, or otherwise fail, an exposed, live conductor or live-conductor end results. Accordingly, it has been found that the exposed conductor occassionally welds itself to the frame of the automobile and otherwise defeats the purpose of the fuse link assembly.  
  These and other disadvantages of the prior art are overcome by the present invention wherein there is provided a fuse link assembly having a minimum number of component parts and therefore, requiring substantially less installation labor than prior art devices. In a preferred embodiment the fuse link assembly of the present invention includes a thermal barrier which functions to thermally insulate the heat generated within the fuse link assembly.  
 SUMMARY OF THE INVENTION Briefly, a fuse link assembly for fusing a conductor is provided. The assembly includes a fuse link member having a reduced cross-section at a given portion thereof, and having first and second terminal portions respectively at opposite ends thereof. First and second cooperating terminals are provided with means for gripping a bare wire, and each cooperating terminal slidably engages one of the first and second terminal portions of the fuse link number. An insulated housing encloses the assembly, and, in a preferred embodiment, provides a thermal barrier about the given portion of the fuse link member.  
 BRIEF DESCRIPTION OF THE DRAWING The advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description when taken in conjunction with the accompanying drawing wherein:  
  FIG. 1 is an assembly view of a fuse link assembly in accordance with the prior art;  
  FIG. 2 is a top view of the internal structure of a fuse link assembly in accordance with the present invention, and illustrating particularly a fuse link member thereof in engagement with cooperating terminals;  
  FIG. 3 is a side view of the structure shown in FIG.  
  FIG. 4 is an end view of the fuse link member of FIG.  
  FIG. 5 is a cross sectional view of the fuse link member taken along the. line 5-5 of FIG. 2;  
  FIGS. 6 and 7 respectively show side and top views of the fuse link housing in accordance with the present invention;  
  FIG. 8 is an end view of the fuse link assembly housing of FIGS. 6 and 7, and further illustrating the hinge member in its alternate positions; and,  
  FIG. 9 is a side view of the housing of FIGS. 6-8 showing the position of the fuse link member structure of FIG. 2 therein.  
 DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to FIG. I there is shown generally at 10 a fuse link assembly in accordance with the prior art. Fuse link assembly 10 functions to fuse a conductor 12 between its adjacent ends 12a and 1212. Assembly 10 includes a fuse wire 14 which typically exhibits a size which is four AWG wire sizes smaller than that of conductor 12. The ends of fuse wire 14 are provided with male contacts 16 and 18 which are crimped, soldered or suitably fastened onto fuse wire 14. Contacts 16 and 18 are respectively enclosed within housings 16a and 18a. The adjacent ends of conductor 12 are provided with suitable female contacts 20 and 22. Similarly, contacts 20 and 22 are respectively enclosed within housings 20a and 22a. Contacts 20 and 22 are also crimped, soldered or suitably fastened to the adjacent ends of conductor 12.  
  It can be seen that fuse link assembly 10 necessitates four housings, four contacts and a fuse wire. Moreover, it will be appreciated by those skilled in the art that utilization of assembly 10 of FIG. 1 necessitates substantial labor in that four crimped joints must be provided and that four housings must be assembled. As will be discussed more fully hereinafter, the fuse link assembly in accordance with the present invention substantially reduces the component count and, accordingly, simplities the labor requirements as compared to the numerous elements and associated labor requirements of assembly 10 of FIG. 1.  
  Referring now to FIGS. 2 and 3 there is shown generally at 30 a metallic fuse link member 32 in engagement with cooperating male connector terminals 34 and 36. As best illustrated in FIG. 4, fuse link member 32 is provided with curls 38a and 38b (and 38a and 38b), thereby to provide integral, female-connector-terminal end portions. Accordingly, the end portions of fuse link member 32 cooperate with and function to accept the spade portions of connector terminals 34 and 36. Terminals 34 and 36 are respectively provided with wire barrel portions 34a and 36a. As is well known in the art, these wire barrel portions are adapted to accept a bare wire for crimping therein.  
  The central portion of fuse link member 32 is provided with a suitable aperture 32a such that the current carrying cross section of the central portion (as best illustrated in FIG. 5) is of an area which is substantially less than the current carrying cross-sectional area of the associated conductor. For example, in one embodiment, the cross section of the central portion of fuse link member 32 is approximately four AWG wire sizes smaller than the cross-sectional area of the bare wire conductor which has its ends crimped into male terminals 34 and 36. It can also be seen that fuse link member 32 is provided with side rails 32b, which are readily formed by turning a portion of the edge of member 32 through a right angle. As will be discussed more fully hereinafter, rails 32b afford sufficient structural strength to member 32, thereby to prevent bending or kinking of member 32 particularly at the central portion thereof.  
  Hence, it should now be appreciated that fuse link member 32, in a preferred embodiment of the present invention, comprises a substantially rigid and generally rectangular unitary metallic member, having a reduced cross section at an integral portion thereof, and having first and second integral terminal portions respectively at opposite ends thereof.  
  Referring now to FIG. 6, there is shown a side view of an insulated housing 40. The composition of housing 40 preferably comprises nylon, vinyl or any other suitable insulating material. Housing 40 includes a top portion 40a which is hinged about lower portion 40b.  
 Upper portion 40a includes a ring 42 which engages a clasp 44 of lower portion 40b. Ring 42 and clasp 44 function to snap-lock housing 40 in its closed position. Lower portion 40b also includes raised portions or pads 46.  
  Turning now to FIG. 7 there is shown a top view of housing 40 wherein top portion 400 is shown in its open position. The end portions of housing 40, as illustrated in FIGS. 6 and 7, is preferably reduced to a circular cross section having a diameter which approximates that of the outside diameter of the insulation portion of the associated conductor to be fused.  
  In FIG. 8 there is shown an end view of housing 40 and further illustrating upper portion 40a in both the closed and open positions. FIG. 8 also illustrates an integral hinge 48 which results when housing 40 is suitably molded in a mold housing as is well known in the art.  
  Referring now to FIG. 9 there is shown a side view of housing 40 in its closed position with fuse link member 32 and male connector terminals 34 and 36 disposed therein in engaged relation. It can be seen that the length of fuse link member 32 is selected such that the gussets or transitional portions of terminals 34 and 36 respectively rest upon pads 46. Further, it can be seen that the relative dimensions of housing 40 and the thickness of fuse link member 32 are selected such that an air barrier results between the surface of fuse link member 32 and the inner chamber of housing 40. Accordingly, an air-insulated barrier is provided therein. It will be appreciated&#34; by those skilled in the art that the conductor to be fused with the fuse link assembly of the present invention is suitably crimped or fastened at its adjacent ends to the fuse link assembly within the wire barrel portions of terminals 34 and 36.  
  The operation of the fuse link assembly in accordance with the present invention is described as follows. It is assumed that the fuse link assembly is suitably connected between the adjacent ends of the conductor to be fused by way of the wire gripping means provided at the ends of terminals 34 and 36. In response to an overload or high-current fault, fuse link member 32 melts at the central portion thereof. Since the central portion of fuse link member 32 has a reduced cross section, the heat generated is localized thereat. Since there is no direct contact between fuse link member 32 and housing 40, the generated heat is isolated within the housing by virtue of the thermallyisolating air barrier established therein.  
  It should now be appreciated that once the fuse does melt or blow, it can be readily replaced with a new fuse link member 32. It should be noted that terminals 34 and 36 are preferably provided as male members in that they are thereby virtually impervious to the generated heat. That is, there is essentially no chance of damaging the male tabs, as the resulting temperatures thereat are insufficient to anneal the material of the tab. Further, any damage that does result to the female connector portions offuse link member 32 is of no consequence, as this part is replaced after the fuse melts or blows.  
  It should be appreciated, however, that in a given application, terminals 34 and 36 can advantageously be provided in the form of female connector terminals. It should also be noted that aperature 32a can be provided in any given geometric pattern other than the preferred circular aperture shown in the relevant figures of the present specification. As previously discussed, fuse link member 32 is preferably provided with means for increasing its bending strength such as, for example, side rails 32b. This feature provides for a more rugged member which therefore will not deform during the installation operation when the cooperating male tab terminals are inserted therein. Hence, the dimensional requirements for an air-insulated barrier within housing 40, in accordance with the present invention, are maintained.  
  It will be appreciated by those skilled in the art that the preferred fuse link assembly in accordance with the present invention merely requires two crimp joints for installation. Whereas, however, the prior art devices require four crimp joints and, in many cases, additional soldering.  
  What has been taught, then, is a fuse link assembly facilitating, notably, a fuse link for fusing a conductor such as a conductor in an automotive electrical system. The form of the invention illustrated and described herein is a preferred embodiment of these teachings. It is shown as an illustration of the inventive concept, however, rather than by way of limitation, and it is pointed out that various modifications and alterations may be indulged in within the scope of the appended claims.  
 What is claimed is:  
  l. A fuse link assembly for fusing a conductor, said assembly comprising, in combination: I  
 a substantially rigid unitary metallic fuse link member having a reduced cross section at a given generally central integral portion thereof which melts in response to a given current level in said conductor, said fuse link member having structural means at said given portion formed from the meltable material of said fuse link member for increasing the structural strength of said fuse link member, wherein said structural means comprises at least one turned portion extending through said reduced cross section and projecting away from at least one plane of said fuse link member thereby to resist bending or kinking of said fuse link member at said given portion, and said fuse link member having first and second integral terminal portions respectively at opposite ends thereof;  
 first and second cooperating terminals each cooperating terminal having means for gripping a bare wire and each cooperating terminal slidably engaging one of said first and second terminal portions of said fuse link member; and,  
 an insulating housing enclosing said assembly.  
  2. The assembly according to claim 1, wherein said housing comprises a removable enclosure of insulating material having first and second projections for respectively engaging said first and second cooperating terminals and having a central portion spaced apart from said given portion of said fuse link member, whereby a thermal barrier is provided between said given portion and said insulating enclosure.  
  3. The assembly according to claim 2, wherein said housing includes upper and lower portions, and further including means for removably locking said upper portion to said lower portion.  
  4. The assembly according to claim 1, wherein said first and second terminal portions of said fuse link member each comprise a female connector and wherein said first and second cooperating terminals each comprise a male connector.  
  5. The assembly according to claim 1, wherein said reduced cross section is formed by providing at least one aperture in said fuse link member at said given portion thereof.  
  6. The assembly according to claim 1, wherein said structural means comprises at least one side rail wherein at least one edge portion of said fuse link is turned through a right angle to form said side rail.