Patent Publication Number: US-3879695-A

Title: Rejection type fuseholder

Description:
United States Patent Oakland et al.  
 [ REJECTION TYPE FUSEHOLDER [7S] lnventors: Frederic Oakland. Hales Corners;  
 Elmer M. Kunath. Milwaukee; John A. Rauenbuehler, New Berlin. all of Wis.  
 [73] Assignee: Cutler-Hammer, Inc., Milwaukee.  
 Wis.  
 [22] Filed: Oct. 3, 1973 21 Appl. No.: 403,258  
 [52} US. Cl. 337/225; 200/42; 317/119; 337/209 [51] Int. Cl. H0lh 85/24 [58] Field of Search 337/225. 226. 209; 200/42: 317/119 [56] References Cited FOREIGN PATENTS OR APPLlCATlONS 18.026 1 1914 France 337/225 24,108 3/1931 Netherlands 337/225 27.323 2/1927 Netherlands 337/225 Apr. 22, 1975 767.335 7/1934 France 337/225 Primary l:&#39;.\&#39;aminer.lames D. Trammell Assistant Examiner-Fred E. Bell Attorney, Agent, or Firm-H. R. Rather; Wm. A. Autio [57] ABSTRACT A rejection type fuseholder is disclosed for accommodating specially constructed fuses.  
 The fuseholder dimensionally gages a fuse for fit into a main portion of the fusebody and into a circuit completing compartment also contained therein.&#39;For this purpose the fuseholder includes a generally hollow housing having a plurality of cylindrically shaped cavities of varying diameters to which a fuse must conform in order to be physically acceptable therein. A movable contact is reciprocally mounted within one of such cavities for completing circuit through a fuse only if the fuse has a particular fuse tip configuration to engage the movable contact.  
 9 Claims, 10 Drawing Figures we 10: 3 I34 72 race REJECTION TYPE FUSEI-IOLDER BACKGROUND OF THE INVENTION This invention relates to electric cartridge-type fuseholders and more particularly to fuseholders of special construction for cooperating with specially constructed fuses.  
  Various fuseholders have been devised for preventing installation of standard fuses within a fuseholder in applications where safety demands fuses having particular circuit interruption ratings and characteristics. Although these devices have generally served their purpose, they are not entirely satisfactory because they usually rely on either a rigid or flexible interference member mounted in the fuse clip itself to block insertion of those fuses which do not conform to the interference member. Such devices are sometimes easily defeatable by overstressing the fuseholder during insertion. Moreover, the structural makeup of such devices may still permit a standard fuse to be electrically connected to complete a circuit even though such fuse is not properly seated within the fuseholder.  
  It is believed that such problems can be reduced by use of a fuseholder which not only physically gages the fuse for proper fit within the fuseholder, but also gages a portion of the fuse for fitting into a specially constructed circuit completing compartment of the fuseholder.  
 SUMMARY OF THE INVENTION The general object of the invention is to provide an improved fuseholder which circumvents the problems heretofore noted as well as other disadvantages of the prior art.  
  More specifically it is an object of the present invention to provide a fuseholder of improved construction which ensures rejection of improper fuses.  
  It is a specific object of the present invention to provide a novel construction for fuseholders which is adapted to accommodate fuses having special characteristics and which physically and electrically sizes fuses for such characteristics rejecting and otherwise preventing circuit completion of those which do not conform to a particular configuration within the fuseholder, and hence, prevents insertion of fuses with improper voltage ratings therein.  
  It is a further object of the present invention to provide a specially constructed fuseholder of the rejection type which is of relatively simple construction, is capable of manufacture at low cost, has a minimum number of parts and is so designed to be readily and easily assembled in mass production operation.  
  These and other objects and advantages of the invention will become more apparent in the following specification and claims when read in conjunction with the following drawings.  
 DETAILED DESCRIPTION OF THE DRAWINGS In describing the present invention, reference will be made to the accompanying drawings forming a part of the instant disclosure wherein:  
  FIG. 1 is a plan view of the rejection type fuseholder of the present invention.  
  FIG. 2 is a sectional elevation view of the fuseholder in FIG. 1 taken along line 2-2 illustrating the advantageous constructional features of the present invention which physically and electrically size fuses.  
  FIG. 3 is a side elevation view of the fuseholder in FIG. 1.  
  FIG. 4 is a plan view of the upper terminal plate shown in FIG. 2.  
  FIG. 5 is a plan view of the lower terminal plate, pigtail and movable brass plate assembly shown in FIG. 2.  
  FIG. 6 is a side elevation view of a modification to the fusebody shown in FIG. 2 providing for an alternate circuit completing arrangement for the fuse shown therein.  
  FIG. 7 is a plan view of the contact assembly shown in FIG. 6.  
  FIG. 8 is a plan view of the lower contact terminal plate shown in FIG. 6.  
  FIG. 9 is a side elevation view of a further modification to the fusebody shown in FIG. 2 providing for another alternate circuit completing arrangement for the fuse shown therein.  
  FIG. 10 is a plan view of the one piece contactor and terminal plate subassembly shown in FIG. 9.  
 DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1-3 of the drawings, the rejection type fuseholder of the present invention is shown comprising a generally hollow fuse post body or housing 10 having discriminating means therein to preventing insertion or electrical connection of fuses with improper voltage ratings, the details of which form a major portion of the invention.  
  Housing 10 is a two part molding comprising sections 14 and 15 and is constructed of a durable electrical insulating material such as a phenolic thermoset resin or the like having high heat resistance characteristics and dimensional stability. Each section has integral projections 18-21 and 22-25 respectively, protruding from one side thereof as shown in FIGS. 1 and 2, each of which join together upon assembly of sections 14 and 15 to form an external terminal compartment.  
  Sections 14 and 15 are additionally provided with cavity forming depressions molded therein which, when joined together, form compartments or cavities to accommodate a rejection type fuse element such as a ferrule type cartridge fuse shown in FIG. 2. The cavity thus formed is generally cylindrically shaped being open at its outer end 32 and closed at its inner end 34.  
  Open end 32 is closed by a conductive closure member such as the fuse cap shown in FIG. 2. Fuse cap 40 is a three piece member comprising an overcap 42, conductive tube 44 and a spring steel retainer 46. Overcap 42 is constructed of a durable electrical insulating material such as a phenolic thermoset resin or the like and is press fit onto one end of conductive tube 44 suspending the open exposed end of tube 44 into cavity as shown in FIG. 2. Tube 44 is constructed of a good electrical conducting material such as brass and is adapted to receive and abut with conducting end portion 30a 0f fuse 30. Tube 44 has an aperture 52 in its side wall through which retainer 46 extends to press against fuse tip portion 30a to secure the fuse within tube 44 and thereby facilitate its insertion and extraction from cavity 50. The opposite end of the retainer 46 is secured by press fit between side walls 42a and 44a, respectively, of overcap 42 and tube 44. Tube 44 is externally threaded at its open exposed end and is adapted to be screwed into tapped hole 54 in upper terminal plate 56 seating overcap 40 against shoulder 10a while concurrently securing fuse cap 40 to housing 10.  
  Upper terminal plate 56 is constructed of a good electrical conducting material such as brass and is shaped as shown in FIGS. 2 and 4 as having an octagonal end portion 560 within cavity 50 and an integral elongate portion 56b projecting through a rectangularly shaped channel 58 in housing 10. Plate 56 is secured within channel 58 and octangular recess 60 in cavity 50 by the clamping action of sections 14 and 15 during their assembly. Plate 56 is further provided with a captivated terminal wire clamp and screw assembly 62 at its opposite posterior end for fastening an external lead line (not shown).  
  Cavity 50 is a generally cylindrically shaped chamber having two stepped down diameter portions 50a and 50b which are connected through an opening 500 to cavity 64. Both portions 50a and 50b are sized to receive body portion 30b and the two stepped down fuse tip portions 300 and 30d of fuse 30. A shoulder 66 is located at the transition point between cavity portions 50a and 50b to limit inward travel of fuse 30. The outer shoulder of fuse tip portion 30c abuts thereagainst while the reduced fuse tip portion 30d projects into &#39;cavity portion 50b to complete circuit with a movable contact 70 therein.  
  Contact 70 is constructed of a good conducting material such as brass and is secured by an integral rivet 72 to a rigid brass plate 74 as shown in FIGS. 2 and for movement within the bore of cavity portion 50b. Brass plate 74 is movable within cavity 64 which is located immediately below and in line with cavity portion 50b. Brass plate 74 is spring biased against top wall 64a of cavity 64 as shown in FIG. 2 by a pair of conical compression springs 80 which are seated in the recessed portion of cavity bottom wall 64b. Consequently, movable contact 70 is biased into the bore of cavity portion 50b in a position to complete circuit with fuse tip portion 30d. It is to be noted that movable contact 70 is of sufficient length to remain at least partially within the bore of cavity portion 50b even though fully depressed as rivet 72 will abut against the raised shoulder in bottom wall 64b to limit its travel.  
  Moreover, this construction also limits transverse motion of brass plate 74 with depression of movable contact 70. A copper braid 84 is spot welded to an upper inner corner of plate 74 at one end and is routed through a channel 88 and spot welded to the innere end 90a of lower terminal plate 90 as shown in FIGS. 2 and 5.  
  Lower terminal plate 90, like upper plate 56, is constructed of a good electrical conducting material such as brass and is generally elongate projecting through a rectangularly shaped channel 92 in housing and resting on projections and 24. Plate 90 is likewise secured therein by the clamping action of sections 14 and 15 and is provided with a captivated wire clamp and screw assembly 94 at its outer end 90b for fastening an external lead line (not shown).  
  Referring now to FIG. 6 there is shown a modification to the fusebody shown in FIGS. l-3 which provides for an alternate circuit completing arrangement for the rejection type fuse shown therein. As can readily be recognized, the modifications thereto are confined to the contact compartment in the lower housing portion wherein contact 70 is riveted by rivet 72 to a flexible conducting member 100.  
  Conducting member 100 shown in FIGS. 6 and 7 is constructed of a good conducting material such as brass and is movable within modified cavity 102 located immediately below and in line with cavity portion 50b. Conducting member 100 has two pre-sprung legs 100a and 100b which slideably bear against lower terminal plate 104 to bias contact into the bore of cavity portion 50b in a position to complete circuit with fuse tip portion 30d. Rivet 72 projects sufficiently below member to act as a stop member against plate 104 to ensure contact 70 remains at least partially within cavity portion 50b even though fully depressed.  
  Terminal plate 104 is constructed of a good electrical conducting material such as brass and is shown in FIGS. 6 and 8 as being generally elongated projecting through a rectangularly shaped channel 108 in housing 10 and is secured therein by the clamping action of modified sections 14 and 15 (not shown).  
  Referring now to FIG. 9, still another modification to the contact compartment and elements therein is shown for completing circuit with a rejection type fuse shown in FIG. 2.  
  A flexible C-shaped brass contactor shown in FIGS. 9 and 10 is welded to lower terminal plate 122 and seated in recess 124a within modified cavity 124. Terminal plate 122 is shown in detail in FIGS. 9 and 10, and like plate 104 is likewise clamped in a channel 126 in housing 10 by the clamping action of modified sections 14 and 15 (not shown).  
  Thus it will be apparent to those skilled in the art that the present invention provides a substantial improvement towards ensuring rejection of fuses having voltage ratings different from a preferred fuse of special construction. It will also be readily recognized that the unique internal fusebody arrangement and interaction of circuit completing parts therein provide rejection capabilities for fuseholders which are not readily defeatable, and yet which are relatively simple and inexpensive to manufacture.  
  While the fuseholders hereinbefore described are effectively adapted to fulfill the objects stated, it is to be understood that the invention is not intended to be confined solely to the particular embodiments disclosed or for use solely with totally enclosed fuseholders, inasmuch as it is adaptable for use with simple open sided fuseholders or fuseblocks having a plurality of fuse clips therein. It is to be further understood that the present invention is susceptible of even further modifications than those disclosed without departing from the scope of the appended claims.  
 We claim:  
  1. A fuseholder of the rejection type for a fuse having a specially constructed fuse tip configuration, comprismg:  
 an insulating housing having a plurality of communicating compartments including two generally cylindrical shaped concentric bores the first of which is dimensionally sized to block and limit the insertion of the main body portion of a fuse having dimensions exceeding the physical dimensions of said first bore and the second of which is generally smaller than said first bore to further limit and block entry of a fuse that does not have the desired fuse tip configuration and a cavity adjacent to and opening to said second bore; 1 an electrical contact with said cavity;  
 spring biased means within said cavity and biasing said contact for reciprocal movement in said bore for engagement with a tip of a fuse having said special configuration;  
 means for securing a fuse which fits within said bores in said housing and effecting electrical conductive engagement with the end of said fuse opposite that having said special tip configuration, and  
 external terminal means mounted on said housing and having electrical connections with said contact and said securing means.  
  2. A fuseholder according to claim 1 wherein said spring biased means comprises a conductive plate and a pair of conical compression springs; wherein said plate is in circuit with said external terminal means; and wherein said springs are attached to said plate and are seated in one wall of said cavity to resiliently urge said plate against the opposite cavity wall thereto to urge said contact within said second bore.  
  3. A fuseholder according to claim 1 wherein said spring biased means is a resilient conducting member for slidably engaging said external terminal means; and wherein the resiliency of said resilient member causes said member to urge said contact into said second bore.  
  4. A fuseholder according to claim 2 wherein said resilient conducting member is a one-piece member including two resilient legs for conductively engaging said external terminal means.  
  5. A fuseholder according to claim 1 wherein said means for securing said fuse within said housing is a closure member adapted to be releasibly secured to said housing and to receive the fuse tip end opposite said special fuse tip configuration.  
  6. A fuseholder according to claim 5 wherein said closure member comprises an overcap, conducting tube and fuse retainer means; wherein said overcap is constructed of an insulating material encapsulating one end of said tube; wherein said external terminal means includes two terminal plates, the first of which is in circuit with said contact; wherein said tube is adapted at its exposed end to conductively engage the second of said terminal plates; wherein said tube is further adapted to conductively receive the conducting portion of said fuse end opposite the end having the specially constructed fuse tip configuration; and wherein said retainer is attached to said tube and cooperates therewith to releasibly secure said fuse to said tube.  
  7. A fuse holder of the rejection type for a fuse having a specially constructed fuse tip configuration, the fuseholder comprising:  
 an insulating housing having a plurality of communicating compartments at least one of which is adapted to accept a fuse physically conforming thereto;  
 means for securing said fuse within said housing and for conductively engaging one end of said fuse; external terminal means mounted to said housing and in circuit with said securing means; and  
 a movable electric contact also in circuit with said external terminal means and being operable within a second compartment to conductively engage said specially constructed fuse tip configuration when said configuration physically conforms to said one compartment and physically engages said contact.  
  8. A fuseholder according to claim 7 wherein said movable contact is a resilient one piece generally C- shaped conducting member and is operable to engage said special fuse tip configuration within said second compartment.  
  9. A fuseholder according to claim 7 wherein said movable contact is operable to engage said special fuse tip configuration within said one compartment.