Patent Publication Number: US-3876278-A

Title: Fuse holder contact

Description:
United States Patent Battaglia et al.  
 FUSE HOLDER CONTACT Inventors: Dino Battaglia; Guido Vignoli, both of Turin, Italy Assignee: AMP Incorporated, Harrisburg. Pa.  
 Filed: Sept. 27, 1973 Appl. No.: 401,464  
 Foreign Application Priority Data Oct. 11. 1972 Italy 30368/72 U.S. CI. 339/256 R; 337/187; 339/259 F Int. Cl. H01!&#34; 13/16 Field of Search 339/256, 258, 259, 252;  
 References Cited UNITED STATES PATENTS 12/1926 Frasse 339/252 F Apr. 8, 1975 Carter.............. 339/258 C Macha et al 339/259 F Primary Examiner-Joseph H. McGlynn Attorney, Agent, or Firm-William J. Keating; Jay L. Seitchik; Frederick W. Raring 4 Claims, 3 Drawing Figures I I r 1 J6 g w dlm j PZJENTED APR 81975 SHEET 1 BF 2 FUSE HOLDER CONTACT The present invention relates to an electrical contact for a fuse holder.  
  According to the present invention, an electrical contact for a fuse holder is made from resilient electrically conductive material and comprises an elongate spring arm having an identation formed in a first surface adjacent one free end for receiving an end of a fuse, the spring arm being folded adjacent the opposite end to define a receptacle contact part having a platform spaced from and overlying the first surface of a portion of the remainder of the spring arm, the fold having a through aperture to permit entry of a mating male contact between the platform and the portion, the portion having at least one embossment extending towards the platform, the male contact being releasably gripped between the embossment and the platform and at least one ear for limiting flexure of the spring arm away from the platform.  
  Preferably. a pair of ears extend from the platform. one on each side of the portion of the spring arm, each ear having a stop for engaging the spring arm on flexure of the spring arm away from the platform.  
  An embodiment of the present invention will now be described, by way of example, reference being made to the Figures of the accompanying drawings, in which:  
 FIG. 1 is a plan view of an electrical contact;  
  FIG. 2 is a cross-section on the line IIII of FIG. 1; and  
  FIG. 3 is a partial cross-section of a fuse holder including a housing containing a pair of electrical contacts as shown in FIG. I.  
  As shown, an electrical contact 1 for a fuse holder is made from a strip of resilient electrically conductive material.  
  The electrical contact 1 includes an elongate spring arm 3 which is formed on a first surface 7 adjacent an end 4 with a substantially circular identation 5 which surrounds a generally triangular shaped through aperture 6. Between the identation 5 and the end 4, the surface 7 is formed to provide a lead-in to the aperture 6 for a fuse 8. A fold 10 is formed adjacent the opposite end of the spring arm 3 to define a receptacle contact part 11 having a platform 12 spaced from and overlying the surface 7 of a portion 13 of the remainder of the spring arm 3. The fold 10 has a through aperture 14 to permit the entry of a pair of back-to-back tabs 15, 16 between the platform 12 and the portion 13. A pair of cars 17 extend from the platform 12 one on each side of the portion 13 of the spring arm 3. Each ear 17 has a stop 18 for engaging the spring arm 3 to limit flexure of the spring arm 3 away from the platform 12. A pair of spacer lugs 20 extend from each side ofthe platform. Each spacer lug 20 extends laterally outwardly of the platform 12 and is then formed through 90 so that its free end extends beyond the portion 13 of the spring arm 3. A longitudinally extending slot 21 is formed in the portion 13 of the spring arm 3 and an embossment 22 is formed on the first surface 7 on each side of the slot 21. A locking lance 24 is formed from the platform 12 and a pair of spaced ribs 2. (only one shown) extend from the platform 12 towards respective embossments 22.  
  Referring in particular to FIG. 3, the fuse holder includes a housing of insulating material having a pair of passageways 32 each receiving an electrical contact l, and a cap 31 releasably securable to the housing. The electrical contacts 1 are assembled within their respective passageways 32 via an opening 33 in the housing 30 on separation of the cap 31 from the housing 30. On insertion of a contact 1 into a passageway 32, the lance 24 snaps behind a shoulder 35 formed in the passageway 32 to lock the contact 1 in the passageway. The aperture 14 in the fold 10 is in alignment with a hole 34 communicating with the passageway 32 from the outside surface of the housing and the end 4 of the spring arm 3 extends out of the passageway into a space between the housing 30 and the cap 31. The spacer lugs 20 locate the receptacle contact part 11 in the passage way 32 and ensure that the portion 13 ofthe spring arm 3 can flex away from the platform 12 without engaging the walls of the passageway 32.  
  As shown, a pair of tabs 15, 16 arranged back-toback are inserted through the hole 34 and aperture 14 and between the platform 12 and the portion 13 thereby exerting a force on the portion 13 via the embossments 22 which causes the portion 13 to arch flexibly away from the platform 12. The stops 18 on the ears engage the spring arm 3 as it is flexed away from the platform 12 thus causing the end 4 to deflect in a direction towards the platform 12 or as seen in FIG. 3 will cause the ends 4 of the respective contacts 1 to move towards each other. The tabs are gripped releasably by the ribs 23 on the platform 12 and the embossments 22 on the portion 13. The slot 21, in effect causes the portion 13 of the spring arm 3 to act as two spring beams and the embossments 22 provide high contact pressure areas between the portion 13 and the tabs l5, 16.  
  A fuse 8 can be loaded between the two spring arms 3 of the electrical contacts 1, each end of the fuse 8 engaging in an aperture 6 ofa spring arm 3. The generally triangular shape of the aperture enables the sides of the aperture to engage a conical ended fuse at three spaced contact points. These contact points share between them the contact pressure between the fuse and the contact and the provision of three high pressure contact points has been found to give a satisfactory electrical engagement offering a low resistance be tween the fuse and the contact.  
  On engagement of the fuse 8 with a spring arm 3, the spring arm flexes or pivots about the point of engagement of the spring arm 3 with the locking ears 17 and about the points of contact with the embossments 22. The effect of this is to deflect the ends 4 of each contact 1 within a predetermined deflection range in a direction away from each other. The pre-deflection caused by engagement of the tabs 15, 16 in the contact part 11 of each contact permits of a low initial insertion force requirement on the fuse 8 to locate it correctly between the contacts 1.  
  Although, reference has been made to a pair of backto-back tabs l5, 16 being inserted between the platform 12 and the portion 13, clearly the dimensions of the aperture 14 and the spacing between the platform 12 and the portion 13 can be selected to accommodate a single tab of a predetermined width and thickness.  
 What is claimed is:  
  1. An electrical contact for a fuse holder, the contact being made from resilient electrically conductive material and comprising an elongate spring arm having an indentation formed in a first surface adjacent one free end for receiving an end of a fuse, the spring arm being folded adjacent the opposite end to define a receptacle contact part having a platform spaced from and overlying the first surface of a portion of the remainder of the spring arm, the fold having a through aperture to permit entry of a mating male contact between the platform and the portion, the portion having at least one embossment extending towards the platform, the male contact being releasably gripped between the embossment and the platform, at least one ear extending from one of said platform and said portion and overlying the other for limiting flexure of the spring arm away from the platform. said ear being disposed intermediate said through aperture and said free end, and a spacer lug extending from each side of the platform and formed so that a free end extends beyond the portion of the spring arm to permit flexure of the spring arm when the receptacle contact part is housed in a passageway of an insulating housing,  
  2. An electrical contact for a fuse holder, the contact being made from resilient electrically conductive material and comprising an elongate spring arm having an indentation formed in a first surface adjacent one free end for receiving an end of a fuse, the spring arm being folded adjacent the opposite end to define a receptacle contact part having a platform spaced from and overlying the first surface of a portion of the remainder of the spring arm, the fold having a through aperture to permit entry of a mating male contact between the platform and the portion, the portion having an elongate slot extending longitudinally of the spring arm, the portion further having two embossments formed on the first surface of the portion and extending towards the platform, one embossment being on each side of the slot, the male contact being releasably gripped between the embossment and the platform and at least one ear extending from one of said platform and said portion and overlying the other for limiting flexure of the spring arm away from the platform, said ear being disposed intermediate said through aperture and said free end.  
  3. An electrical contact for a fuse holder, the contact being made from resilient electrically conductive material and comprising an elongate spring arm having an indentation formed in a first surface adjacent one free end for receiving an end of a fuse, said indentation including a through aperture, the shape of the through aperture being generally triangular, the spring arm being folded adjacent the opposite end to define a receptacle contact part having a platform spaced from and overlying the first surface of a portion of the remainder of the spring arm, the fold having a through aperture to permit entry of a mating male contact between the platform and the portion, the portion having at least one embossment extending towards the platform, the male contact being releasably gripped between the embossment and the platform and at least one ear extending from one of said platform and said portion and overlying the other for limiting flexure of the spring arm away from the platform, said ear being disposed intermediate said through aperture and said free end.  
  4. An electrical contact as claimed in claim 3, in which a pair of ears extend from the platform, one on each side of the portion of the spring arm, each ear having a stop for engaging the spring arm for limiting flex are of the spring arm away from the platform.