US2898424A - Multiple fuse and method of manufacture - Google Patents

Description

Aug. 4, 1959 A. VISCHER, JR 2,898,424

MULTIPLE FUSE AND METHOD OF MANUFACTURE Filed Sept. 15, 1956 2 Sheets-Sheet 2 ALFRED VISCHE'R JR.

(W @ZMWJ M J w- I ATTORNEYS.

United States Patent MULTIPLE FUSE AND METHOD OF MANUFACTURE Alfred Vischer, Jr., Park Ridge, 111. Application September 13, 1956, Serial No. 609,752 24 Claims. (Cl. 200-425) The present invention relates to fuses, and more particularly to multiple fuses of the type comprising a plurality of fusible links which are adapted to be selectively connected into operative engagement in an external circuit.

Although the many advantages of multiple fuses have been recognized for a great number of years and such numerous multiple fuses have been designed and developed in that time, the prior art multiple fuses leave much to be desired, particularly in the way of manufacturing cost and ease of operation. In order to provide a good electrical connection between the fuse links and an associated selector contact member, it is usually necessary to resort to high contact pressures between the fuse links and the contact member or members. As a result, a substantial force must be applied to the fuse in order to move the contact member relative to the fuse links in order to change the particular fuse link which is operatively connected in the Work circuit. Consequently, the operation of the prior art type fuses is particularly difficult and this difliculty is accentuated when a fuse link must be changed in a darkened area because of the problem of indexing the selector member and the new fuse link.

Therefore, a principal object of the present invention is to provide a new and improved multiple fuse.

Another object of the present invention is to provide a multiple fuse which may be manufactured at a sufliciently low cost to enable the competitive marketing thereof.

A further object of the present invention is to provide a new and improved fuse which while safe and reliable in use may be operated with a minimum of force.

A still further object of the present invention is to provide a new and improved fuse which may be manufactured at a minimum cost.

A yet further object of the present invention is to provide a multiple fuse plug which may be easily operated so as accurately to connect a new fuse link into the work circuit after another link has been blown.

Another object of the invention is to provide a new and improved method for manufacturing at least parts of multiple fuse plugs.

Briefly, the above and further objects are realized in accordance with the present invention by providing a screw-in type multiple fuse plug in which a plurality of fuse links ofa common fuse element are respectively mounted on a rotatable carrier member which is supported within the fuse body and which may be manually rotated in step-by-step fashion through a a mechanical advantage mechanism for selectively positioning respective ones of the fuse links in operative engagement with a connector member.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following detailed description taken in connection with the accompanying drawing, in which:

Fig. l is a sectioned elevational' view of a multiple fuse plug embodying the present invention;

Fig. 2 is a sectional view of the fuse plug of Fig. 1

:taken along the line 22 thereof, assuming the entire structure to be shown therein;

2,898,424 Patented Aug. 4, 1959.

Fig. 2a is a sectional view of the fuse taken along the line 2a2a thereof;

Fig. 3 is an elevational view of the fuse plug of Fig. l partly broken away and viewed from along the hue 33 thereof, assuming the entire structure to be shown in Fig. 1;

Fig. 4 is an end view of the fuse plug of Fig. 1 taken along the line 44 thereof, assuming the entire structure to be shown in Fig. 1;

Fig. 5 is an isometric view of a fuse element carrier;

Figs. 6-8 are plan and elevational views of a fuse element in the various steps of manufacture prior to the mounting thereof on the fuse element carrier shown in Fig. 5; and

Fig. 9 is a plan view of a combined gasket and name plate.

Referring now to the drawings and particularly to Figs. 14 thereof, there is shown a multiple fuse plug 10 which comprises a generally tubular plug body or housing member 12 in the central cavity of which is disposed a fuse element carrier member 14. The carrier 14 is arranged to be rotated in step-by-step fashion through a mechanical advantage mechanism which includes an eccentric hub 15 on a cover member 16. As best shown in Figs. 2 and 5, the hub 15 loosely extends through a central aperture 19 in the carrier 14 and a plurality of spaced apart teeth 17 protrude radially from the periphery of the carrier 14. The carrier 14 thus constitutes a spur gear which is adapted to be rotated in an internal spur gear 18 formed integrally with the inner wall of the body 12 by means of a plurality of arcuate teeth 20 which are spaced apart by a plurality of recesses 21. The pitch of the gears are the same but the external gear on the carrier 14 has less teeth than the internal gear 18, one less tooth in the illustrated embodiment of the invention, so that the carrier 14 rotates through a predetermined fraction of three-hundred sixty degrees for each complete revolution of the hub 15. In the illustrated embodiment of the invention the external gear has ten teeth, the internal gear 18 has eleven teeth, and therefore, when the cover 16 is rotated clockwise, through one complete revolution for example, the carrier 14 rotates counterclockwise, through thirty-six degrees.

In accordance with an important aspect of the invention, an electric contact member 22 is mounted on the body 12 and extends along one side of the cavity therein in place of one of the teeth 20 on the internal gear and is resiliently biased toward the carrier to perform two' necessary functions, one, to connect a selected fuse link to one terminal of the fuse plug 10, and two, to coact with the teeth 17 to provide a detent for accurately positioning and maintaining the carrier 14 in the selected position. Considered in greater detail and as best shown in Fig. l, the contact and detent portion of the member 22 is constituted by an inclined resilient finger 24 which extends Within the cavity of the body 12 through an aperture 25 firmly to engage a selected one of a plurality of radially disposed fuse links 26 which are mounted on the carrier 14 with the individual fuse links 26 being positioned between the teeth 17 and emanating from the central portion of the carrier 14. The fuse links 26 are integral parts of a fuse element 27 which has a tubular portion 29 positioned in the aperture 19 between the carrier 14 and the hub 15. The fusible portion 26b of each fuse link 26 is of reduced width and the contact portion 26a is substantially larger to provide a large contact surface against which the finger 24 is pressed. Since the teeth 17 are cycloidal in shape, when the hub 15 is rotated to a position such that the carrier 14 is positioned adjacent the finger 24, even if the selected fuse link 26 plug of Fig. 1

is not accurately aligned with the finger 24, the force exerted by the finger 24 on one of the other of the adjacent teeth 17 rotates the carrier 14 to the proper position.

Considering the fuse plug 10 in greater detail, the plug body 12, which is preferably molded of porcelain or the like, has an external portion 28 to which is threadedly attached a conductive shell 30. The shell 30 provides one terminal of the fuse plug 10. As best shown in Figs. 3 and 4, the contact member 22 includes a fiat arcuate flange 32 which partially surrounds a tubular boss 33 on the plug body 12 and seats on the face of a shoulder 34 on the plug body 12. The ends 32a of the flange 32 are cut on a radius to coact with an arcuate shoulder 36 which extends outwardly from the shoulder 34 diametrically opposite a groove 37 in which the contact finger 24 is positioned. Consequently, when the shell 30 is threaded onto the body 12, an annular flange 40 of the shell 30 firmly presses against the ring 32 to insure good contact. A good contact between the contact member 22 and the shell 30 is maintained by staking the flange 4% through slots 43 in the flange 32 and into recesses 42 in the shoulder 34 which locks the assembly together.

As best shown in Fig. 1, the groove 37 is aligned with the aperture 25 and the upper extremity of the finger 24 extends beyond the carrier 14 and rides on the periphery of an annular shoulder 46 provided on a circular cap portion 48 of the cover 16. The shoulder 46 is seated in an annular rabbet formed by the flat upper surfaces of the teeth 28 and the cylindrical inner wall of the plug body 12. The radius of the shoulder 46 is substantially greater than the radius of the periphery of the carrier 14 so that when the upper end of the finger 24 is riding on the shoulder 46 its contact portion is held out of engagement with the teeth 17 and the fuse links 26. A notch 49 is provided in the plug body 12 in alignment with the aperture 25 and the groove 37 to provide a space into which the finger 24 is moved while it is riding on the shoulder 46. When the cover 16 is oriented so that a recess or notch 50 in the shoulder 46 is positioned in alignment with the finger 24 the natural resiliency of the finger 24 causes it to move toward the carrier 14 and into engagement with one of the fuse links 26. Since, as best shown in Fig. 2, the width of the finger 24 is only slightly less than the space between adjacent teeth 17, and since the teeth 17 have a curved or cycloidal operative surface, when the cover 16 is rotated to a position where the notch 50 is in alignment with the finger 24, the finger snaps toward the carrier 14 and even if a fuse link 26 is not accurately aligned with the finger 24, the finger acting as a detent snaps into engagement with the fuse link 26, rotating the carrier 14 the necessary amount.

The notch 50 has a tapered side 50a which provides a cam surface for elevating the finger 24 onto the shoulder 46 when the cover 16 is rotated in a clockwise direction to change the fuse element. Moreover, the extremity of the finger 24 has a rounded edge portion 24a which cooperates with the tapered side or cam surface 50a to facilitate starting the rotation of the cover 16. Obviously, turning of the cover in a counterclockwise direction is prevented by the engagement of the flat edge 24b of the finger 24 with the flat side of the notch 50. If desired, however, both sides of the notch 50 and finger 24 may be tapered to permit rotation of the cover 16 in either direction. However, in order to insure that a fresh fuse link 26 will be moved into operative position each time that the cover 16 is rotated, it is preferable to permit rotation of the cover 16 in only one direction.

The second terminal of the fuse plug is a conductive plug 53 which is positioned in a hole 54 in the center of the boss 33, and a contact member 55 connects the mounted plug 53 to the fuse element 27. As shown, the plug 53 has a head 69 which engages the outer face of the boss 33 and has an inner end 62 of reduced cross section around which is positioned, and preferably staked, a flat ring portion 64 of the contact member 55. The contact member 55 also includes a resilient finger 66 positioned in a groove 70 in the hub 15 and the end portion 66a of the finger 66 is offset resiliently to engage the common annular portion 29 of the fuse element 27.

The hub 15, which has a cylindrical outer surface, is mounted for eccentric rotation within the plug body 12, by means of a suitable machine screw 74 which extends through a central bore 75 in the plug 53 and is threaded into a bore 72 in the hub 15. The bore 72 is displaced from the central axis of the hub 15 to provide the neces sary eccentricity, so that, as described above, rotation of the hub 15 causes reverse rotation of the carrier 14. As shown, the plug 53 may be counterbored as indicated at 76 to receive the head of the machine screw 74 and provide a flush outer contact surface. Also, the bore 72 in the hub 15 is counterbored as indicated at 78 to facilitate positioning of the machine screw 74 in the bore 72 during assembly since it is preferable that the bore 72 be tapped by the thread of the screw 74 at the time the fuse plug 10 is initially assembled. To this end, the cover 16 may be molded of a suitable plastic such as, for example, Lucite. It is desirable to tap the thread in the bore 72 at the time of assembly so that the axial position of the cover 16 in the plug body 12 is adjustable and remains in the adjusted position. An important function of the screw 74 is to provide an adjustment for the proper venting of gases which are released when a fuse blows. These gases can, therefore, escape between the body 12 and the underside of a suitable annular gasket 82, which is positioned between the cover 16 and the body 12.

In order to facilitate rotation of the cover 16 so as to move a different fuse link 26 into engagement with the finger 24, the external sides 80 of the cap 48 are knurled. Furthermore, a smooth action between the cover 16 and the plug body 12 is provided by means of the gasket 82 which is positioned between the upper face of the body 12 and the inner face of the cap 48. If the cap 48 is formed of a transparent material such as Lucite, the gasket 82 may, as shown in Fig. 9, have a printed outer surface for identifying the size of the fuse, the manufacturer and any other suitable information or advertising.

As shown, the upper end of the cover member 16 has a concave outer surface 84 to reduce the amount of material between the user of the fuse and the fuse links thereby to facilitate the observance of the links 26.

Referring now to Figs. 5-8, for a detailed consideration of the manufacture of the fuse element 27 and its assembly to the carrier 14. In Figs. 6a and 6b, there is shown a fuse element blank which may be suitably stamped from a sheet of fuse material. As best shown in Fig. 6a, the fuse links 26 are alternately spaced on opposite sides of a central rectangular body portion 85 which has its opposite ends 85a and 85b cut on an angle so that a number of the fuse elements 27 may be continuously stamped from a single strip of sheet metal. If desired, the enlarged head portions 26a of the fuse links 26 may correspond in size to the spaces defined by adjacent fuse links 26 so that a number of the elements 27 may be punched from a single sheet with adjacent elements 27 having interfitting links 26. In this manner, a minimum of the fuse material is wasted. Ordinarily, however, the fuse elements 27 are cut from a continuous strip since the cost of the material which is thus wasted is negligible, and the stamping machinery is less complex.

After the fuse element 27 has been stamped from either a strip or a sheet, it is folded over along its center line to the configuration shown in Figs. 7a and 7b. As shown, the fuse links 26 lying on opposite sides of the element 27 are alternately spaced, the contact portions 26a partially overlapping. The folded over unit 27 of Figs. 7a and 7b is then formed into a cylinder as shown in Figs. 8a and 8b and inserted into the central aperture 19 in the carrier 14 with the fuse links 26 extending toward the top of the carrier (toward the left as viewed in Fig. 5). The individual fuse links 26 are then folded back over a ring portion 88 of the carrier 14 between the teeth 17 thereof and the extremities 90 of the links 26 are bent over the undercut shoulders 92 on the ring 88 to hold them in place after the fuse has blown and separated this part from the main body. The common contact portion 29 of the fuse element 27 is thus positioned for continuous contact with the resilient finger 66 of the contact member 55. A transparent disk 92a, suitably formed of mica, is provided for holding the ends of the links 26 in place on the carrier after the portions 26b have blown. The disk 92a has a plurality of radial slots 93 extending from a central aperture for tightly receiving a plurality of upwardly extending radial protrusions 94 provided on the carrier 14, thereby to attach the disk 92a to the carrier 14.

In operation, the fuse plug 10 is threaded in a suitable receptacle or socket in the usual manner, contact with the external work circuit being established by the head 60 of the sleeve 53 and by the shell 30. The carrier 14 is in conducting relationship with the contact member 22 and current is thus transmitted from the shell 30 to the finger 24 and through a fuse link 26 to the common contact member 55 and to the plug 53. Since the finger 24 is resilient and biased toward the carrier 14, it presses firmly against the contact portion 26a of the selected fuse link 26. Similarly, the finger 66 resiliently engages the portion 29 of the fuse ele ment 27.

After the operatively positioned fuse link 26 has blown and it is desired to connect a new fuse link 26 in the circuit, the operator rotates the cover 16 clockwise as viewed in Fig. 2 through one complete revolution. During the initial portion of this rotating movement of the cover 16, the cam surface 24a at the extremity of the finger 24 rides on the cam surface 50a at the side of the notch 50 to lift the finger 24 radially outward into the notch 49 and onto the periphery of the shoulder 46. During the remaining portion of the revolution of the cover 16 the extremity of the finger 24 rides on the shoulder 46 and the finger 24 is thereby kept in the notch 49 and out of engagement with the carrier 14. Consequently, contact between the finger 24 and the fuse links 26 is prevented and, in addition, the finger 24 does not interfere with the easy rotation of the carrier 14.

Since the carrier 14 has one less tooth than the internal gear 18, when the eccentrically mounted hub 15 is rotated through one complete revolution, the fuse carrier 14 is rotated through an angle equal to the spacing between the teeth thereof. Since in a preferred embodiment of the invention ten teeth 17 are provided on the carrier and eleven teeth 20 are provided on the internal gear 18, the carrier 14 rotates through 36 degrees for each complete 360-degree rotation of the cover 16. Consequently, when the cover 16 is rotated through one complete turn, a new fuse link 26 is brought into operative position and engaged by the 'finger 24 as it snaps into place. During the rotation of the fuse carrier 14, the mica disk 92a will likewise be rotated because as discussed above it is secured to the carrier 14.

It will thus be seen that there is provided in accordance with the present invention a multiple fuse element which, while'being reliable in use from an operational standpoint, may be operated by the application of a minimum external'force in order to change the fuse links. An important feature of the fuse 10 is that each of the fuse links 26 has a separate enclosure or nest which restricts the blown fuse particles from ,splattering jg g the mec an sm .11 10 other fuse compartments,

6 While the invention has been described in connection with particular embodiments of the invention, it will be understood that various modifications may be made thereon which are within the true spirit and scope of the invention as defined in the appended claims.

What is claimed as new and is desired to be secured by Letters Patent of the United States is:

1. In a multiple fuse plug, the combination of a body member having an internal gear therein, a fuse element carrier in the form of an external gear, said external gear having less teeth than said internal gear, means for mounting said external gearwithin saidbody in operative engagement with said internal gear, and means ineluding an eccentric structure for actuating the internal gear to drive it relative to said external gear.

2. In a multiple fuse plug, the combination of a housing member formed of an insulating material, carrier means for supporting a plurality of spaced apart fuse links, said carrier means being disposed within a cavity in said housing, cover means for covering said cavity to enclose said carrier means, and means responsive to rotation of said cover means with respect to said housing means for causing said carrier means to rotate with respect to said housing means through an angle less than that through which said cover means is rotated.

3. In a multiple fuse plug, the combination ofa housing including an internal gear, a fuse link carrier including an external gear operatively disposed within said internal gear, said external gear having one less tooth than said internal gear, a plurality of fuse links each respectively mounted on said carrier between the teeth thereof, contact means mounted on said housing at a position corresponding to a tooth of said external gear and resiliently biased toward said carrier, and rotatable eccentric means including structure disposed within said housing for manually actuating said carrier to drive said external gear in said internal gear, whereby for each complete revolution of said eccentric means a new fuse link is operatively connected to said contact means.

4. The combination set forth in claim 3 in which said gears-are spur gears.

5. The combination set forth in claim 4 in which said contact means includes a contact member having a width which is slightly less than the spacing between the teeth of said gears and the teeth of said external gear are bevelled toward the extremities thereof, whereby said contact means provides a detent for properly locating said internal gear.

6. In a multiple fuse plug, a body member having an open cavity therein, a cover for enclosing said cavity,

said cover being rotatably supported by said housing, a fuse element carrier disposed within said cavity, said carrier including an external gear which mates with an internal gear in said body member, and a hub on said cover which loosely engages a portion of said carrier, said hub and said portion of said carrier providing an eccentric connection for driving said external gear in said internal gear.

7. The combination set forth in claim 6 in which the number of teeth on said internal gear differs from the number of teeth on said external gear. 7

8. In a multiple fuse plug, the combination of a housing, a fuse element carrier rotatably mounted in said housing, a plurality of fuse links having portions spaced apart about the periphery of said carrier,resilient contact means mounted at a fixed position in said housing and biased toward said carrier to make contact with a selected one of said fuse links, and rotatable means for rotating said carrier with respect to said contact means to change the fuse link which is in operative engagement with said contact means, said rotatable means including a cam surface for forcing said contact means out of engagement with said fuse links and said carrier.

9. The combination set forth in claim 8 wherein said carrier includes peripheral protruding portions which separate said fuse links and which coact with said contact means to provide a detent.

10. In a multiple fuse plug, the combination of a tubular body formed of an insulating material and having an internal spur gear therein, a fuse element carrier in the form of an external spur gear, said external gear having less teeth than said internal gear, a plurality of fuse links spatially arranged on said carrier, said links being connected together at the central portion of said carrier and having fusible portions extending radially outwardly between said teeth, a contact member mounted in said housing at the position of a tooth in said internal gear and being resiliently biased toward the edge of said carrier, a cover rotatably mounted on said body over the cavity to at least partially enclose said carrier, said cover having a hub portion eccentrically connected to said carrier for driving said carrier in said internal gear when said cover is rotated, and means on said cover for coacting with said contact means for moving and maintaining said contact means away from said carrier while the cover is being rotated to change the selected fuse link.

11. The combination set forth in claim 10 wherein said last claimed means is a cylindrical shoulder having a notch therein.

12. In a multiple fuse plug, the combination of a cavitied housing, a fuse element carrier rotatably mounted in said housing, a plurality of fuse links spatially arranged on said carrier, contact means mounted in said housing and resiliently biased toward said carrier, a cover for enclosing the cavity in said housing, and a circular shoulder on said cover, the periphery of said shoulder engaging a portion of said contact means to move it out of engagement with said carrier, and a notch in said shoulder to receive said contact means and enable connection thereof to a selected one of said links.

13. The combination set forth in claim 12 in which said notched portion includes a tapered surface on only one side thereof for camming said contact means onto said shoulder as said cover is rotated in a particular direction relative to said housing.

14. In a multiple fuse plug, the combination of a housing including an internal gear, a fuse link carrier including an external gear operatively disposed within said internal gear, said external gear having less teeth than said internal gear, a plurality of fuse links spatially arranged on said carrier, contact means mounted at a fixed position on said housing and biased toward said carrier to engage one of said links, and manually rotatable eccentric means disposed within said housing for driving said external gear in said internal gear.

15. In a multiple fuse plug, a body member having an open cavity therein, a cover for enclosing said cavity, said cover being rotatably mounted on said housing, a fuse element carrier disposed within said cavity, said carrier including an external gear which mates with an internal gear in said body member, and means on said cover for driving said external gear in said internal gear.

16. The combination set forth in claim 15 in which the number of teeth on said internal gear differs from the number of teeth on said external gear by one.

17. A plugin type multiple fuse comprising a housing member formed of an insulating material and having a threaded outer portion formed of a conductive material, said housing having a central cavity surrounded by an internal gear integral with said housing, a fuse element support member mounted within said cavity, said support member having radially protruding portions to provide an external gear, said gears having the same pitch, said external gear having one less tooth than said internal gear, a rotatable hub mounted within said cavity, said hub being mounted for eccentric rotation in said housing and being received within an aperture in said support member so that rotation of said hub causes said support member to travel around said internal gear, a plurality of fuse links each respectively disposed between said protruding portions on said support member, detent means fixedly positioned in said cavity for engaging and holding said support member when it occupies a predetermined relative position with respect to said internal gear, conductive means engaging one side of each of said fuse elements, and a contact member fixedly positioned in said cavity for engaging the other side of a selected one of said fuse elements when said detent means is in engagement with said support member.

18. The fuse set forth in claim 17 wherein said detent means includes said contact member.

19. A plug-in type fuse comprising a generally cylindrical insulating housing having a threaded outer portion and internal gear integral therewith, a fuse element support disposed Within said housing and having externally extending portions forming a gear having one less tooth than the spaces between the teeth of said internal gear, said support being mounted within said housing for eccentric rotation in said internal gear, a plurality of fuse elements each being respectively positioned on said support between said extending portions, means connected to said support and extending outwardly from said housing to facilitate manual rotation of said support, and a plurality of mutually insulated contact means mounted on said housing, one of said contact means engaging one side of all of said fuse elements and another of said contact means being mounted in said housing between said internal gear and said support for engaging a selected one of said fuse elements at a location spaced from the location at which said first contact engages the selected fuse element.

20. A fuse element comprising a hollow cylindrical central portion formed of a folded-over and circularized metal sheet and a plurality of spatially arranged fuse links extending from the marginal edges of the foldedover sheet, the adjacent ones of said links extending from opposite sides of said folded over sheet.

21. In a multiple fuse, the combination of a plurality of spaced apart fuse links, contact means for contacting a selected one of said links, said fuse links and said contact means being relatively rotatable, and rotatable selector means rotatable through an angle different from the spacing between said fuse links for causing rotation of said contact means relative to said fuse links to change the one of said fuse links selected, and said selector means and said fuse links being rotatable about a common axis.

22. A fuse element comprising a tubular portion formed of a folded-over and circularized metal sheet, and a plurality of spatially arranged fuse links extending from the marginal edges of the folded-over sheet, the adjacent ones of said links extending from opposite sides of said folded-over sheet.

23. The combination set forth in claim 2 wherein said angle of rotation of said carrier means is equal to the spacing between adjacent fuse links when said cover is rotated through an angle of three hundred and sixty degrees.

24. A multiple fuse element comprising a folded-over metal sheet having a plurality of spatially arranged fuse links extending from the marginal edges of the folded over sheet, the adjacent ones of said links extending from opposite sides of said folded-over sheet.

References Cited in the file of this patent UNITED STATES PATENTS 1,485,636 Skinner Mar. 4, 1924 1,555,638 Davis Sept. 29, 1925 1,848,792 Moss Mar. 8, 1932 1,848,924 Ammerman Mar. 8, 1932 1,914,871 Siarnpos June 20, 1933 2,106,109 Prendergast Jan. 18, 1938 2,498,124 Holmes Feb. 21, 1950 2,579,624 Stanley Dec. 25, 1951

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