US1862297A - Capacitor and method forming the same - Google Patents

Description

June 7, 1932. J, BUTLER 1,862,297

CAPACITOR AND METHOD FORMING 'THE SAME Filed March 15. 1929 INVENTOR Bm mh 51466;

ATTORNEY Patented June 7, 1932 UNrrEn STATES PATENT ri-ica BENJAMIN J. BUTLER, OF SOMERVILLE, MASSACHUSETTS, ASSIGNOR, JBY MESNE AS- SIGN MENTS, T GENERAL ELECTRIC CGIMPANY, A CORPORATIUN OF NEW YORK CAPACITOR AND HIETHOD FORMING- THE SAME Application filed March 15, 1929. fierial No. 347,271.

This invention relates to capacitors which include an improved anchor for the terminal tabs such as are used in paper condensers.

Hitherto in the manufacture of rolled paper or series stack condensers comprising alternate sheets of dielectric and foil wound on a mandrel, or assembled in alternate layers, it has been customary to insert strips of foil in contact with the armatures of opposite polarity to serve as terminals for such armatures. In the manufacture of paper condensers of small capacity, the thinness of the roll, i. e., the small number of turns of paper and foil does notgive suflicient pressure to grip the terminal tabs, the result being that the tabs are often disarranged or pulled out of position in the subsequent handling and processing of the unit. An attempt to overcome this diflicultv has been made by providing terminal tabs with a plurality of anchoring lugs or extensions. These members are difficult and costly to make, involving expensive tools to punch out the variegated shapes of terminals, and in addition, the extra metal required for these difi'erent shapes increases the cost very markedly.

It is an object of the present invention to provide an improved terminal tab for paper condensers, which is characterized by its simplicity of structure and ease of manufacture and insertion.

It is a further object of this invention to provide such a terminal tab which is economical to manufacture and permits marked economies in the preparation of the finished condenser.

In the drawing, like numerals refer to similar parts of the several views, of which Fig. 1 'is a plan view of an improved tab terminal of the present invention;

Fig. 2 is a perspective view of a paper condenser showing in dotted lines the location of the tabs when in use; and

Fig. 3 is a section taken on line 33 of Fig. 2 showing the locking of the tab by the condenser foils and dielectrics.

As noted, the terminal tab, designated gencrally by the numeral 1, comprises a generally rectangular strip of metal, the preferred embodiment being tinned brass, although it will be understood that any suitable metal, such as tin foil or the like, may be used. This terminal strip may be made of stock .002 of an inch thick and A of an inch wide, al-

though it will, of course, be fully appreciated that these dimensions are given merely by way of example, and any variation in the size to accommodate the structure to condensers of different capacities, is fully comprehended in the spirit and scope of this invention.

At one end of the terminal, one or more holes 2 of any suitable size and configuration are punched out of the metal. When such a terminal is inserted in a condenser roll between a sheet of flexible dielectric such as paper and an armature, the paper and/or foil can be forced to enter into the holes in the tab thus gripping the tab firmly, and preventing it from being pulled out.

Where capacitors of large dimensions are used, and terminal tab strips of thicker or harder material inserted, the locking aperture or surface break 2 may have its edge or edges suitably beveled, in order to prevent rupture (by shearing) of the juxtaposed foils and dielectrics of the capacitor by the edges of the terminal tab surface breaks or holes.

The tabs are shown in position in the rolled condenser of Fig. 2, the foils being designate generally by the numeral 3 and the paper dielectric by the numeral 4. The foils are shown in dotted lines, the upper and lower boundaries being designated generally by the numerals 5 and 6 respectively. The tabs are inserted in the condenser for a substantial portion of their length, usually one-halt or more of their total overall length, that is, the tabs extend into the capacitor over approximately the total width of the capacitor 90 foil strips 3, the minimum distance being indicated in Fig.1 by the distance between dotted line 7 and the left end of tab 1. Butas shown in ll ig'. 2 a part of that length of tab 1 lies outside capacitor toils 3 and between dielectric sheets i, so that when, as pre- "ferred, and as shown in Fig. 3, a plurality; of holes 2 or depressions are formed in a row along the length oftab 1, said row extends substantially over the entire length of the to!) terminal tab 1 which lies adjacent capacitor foils 3; the useful result being that not only are the tabs 1 heldagainst foils tending to pull them out of the capacitor but are prevented from being shifted into different angular positions inside the capacitor.

In the assembly of the condenser, the condenser elements are wound loose with the terminal tabs inserted at the proper places in the roll. The wound roll is then sent to the clamping room where it is pressed in a clamp by applying a pressure of substantially 25 to 50 pounds per square inch. During this process of applying pressure, the dielectric sheets and the foils enter the holes in the terminal tab, as can be appreciated from an inspection of Fig. 3, thereby firmly anchoring the tab in its position in the roll. The tabs so anchored are so firmly held in position that they cannot be pulled out without disrupting the condenser structure proper, or being themselves torn, if made of soft metal. After compression, the compressed unit is subjected to the usual impregnating and finishing steps and then provided with suitable terminal leads, the whole structure subsequently being inserted in a casing or canister and embedded in pot head or other insulating composition, if desired. The impregnating material, for cooling and solidifying aids in holding in interlocking relations, the portions ofthe capacitor sheets which have been forced into the holes or depressions 2, even after the clamps have been removed.

It will be appreciated that the basic concept of this invention comprehends the idea of forcing the condenser body itself, i. e., the foils and dielectrics into a depression in the tab so as to provide a combination of a frictional and a positive lock.

Since the total positive locking effect is a function of the contacting surface of the depressed portions of the dielectric or foil or (as shown) both the dielectric and foil, it will be appreciated that the shape of the depressions in the tabs may be varied to suit the exigencies of any particular construction.

While the improved condenser is shown as comprising a tab having an aperture or hole, it will readily be appreciated that the advantages of the invention may be secured, in part, by forming the tab with a dished portion or portions constituting a break on one or both sides of the flat surface of the tab in the same general sense in which the hole constitutes such breaks inboth surfaces of the strip tab. Likewise it will be understood that although a roll condenser has been described as a preferred embodiment the principles herein set forth are applicable to paper stack condensers.

The simplicity of the tab of the present invention permits a'marked saving in manufacturing cost, due to the fact that a mere punching operation is required to provide a firm anchor, and the percentage of rejections of finished condensers due to disarranged or torn terminals is reduced to a minimum.

I claim: I j

1. A method of forming a capacitor, which consists in laying a terminal tab having flat surface broken in one part,between a continuous foil and a continuous dielectric to form part of a capacitor, and subjecting the capacitor to sufficient pressure to cause the said foil anddielectric to be displaced into close engagement with the interior of the break in the surface, and impregnating the displaced parts to hold them in position to lock the tab.

2. A'capacitor including a flat tab terminal having-a break in its fiat surface, and continuous flexible foil and continuous flexible dielectric extending over the flat surface of the terminal and bending into and out of the break, said bends holding the tab against sliding on the foil and dielectric.

3. A capacitor including a. flat tab terminal having a hole in its flat surface, and continuous flexible foil and continuous paper dielectric extending over the flat surface of the terminal and bending into and out of the hole to hold the tab against sliding on the foil and paper.

4. A capacitor including a flat tab terminal having a hole in its flat surface, and layers of foil wound between a continuous sheet of paper, one of said layers extending across and lying in contact with said tab and bend ing into and out of the hole to hold the tab against sliding on the foil and paper.

5. A capacitor including a pair of flat tab terminals each having a hole in its flat surface, a pair of continuous layers of foil, a

- sheet of continuous paper between said layers of foil, one of said layers extending across and lying in contact with one tab and bending into and out of the hole therein to hold the tab against sliding on the foil and paper,

the other of said layers extending across and lying in contact with the other tab and bending into and out of thehole therein to hold the tab against sliding on the foil and paper.

6. A capacitor including a flat tab terminal having a hole in its flat surface, a continuous flexible foil and continuous paper dielectric extending over the flat surface of the terminal and bending into and out of the hole to hold the tab against sliding on the foil and paper, and a casing holding the foil and paper down on the tab.

7. In the art of making capacitors including adjacent sheets of dielectric paper and of metal armature foil, the method of anchoring terminal strips in the interior of such a capacitor, which consists in winding such sheets in a relatively loose roll. and placing a portion of a terminal strip of which a relatively small portion is perforated. in such position inside such capacitor that the perforated portion lies between and adjacent the paper and foil capacitor sheets"; then compressing the loosely wound sheets and interposed terminal strip together under substantial mechanical pressure thereby establishing good electrical. contact'between the surface of the foil-sheet armature and the relatively large non-perforated surface of the terminal strip, and by said compression also forcing into the perforation in the terminal strip, the portions of the sheets of paper and foil lying on opposite faces of the terminal. strip adjacent the perforation thereby holding the portion of the terminal strip inside the capacitor in its position adjacent the armature foil; and then impregnating the capacitor including the interior of the paper sheet thereby tending to maintain said mechanical and electrical relations of the paper dielectric and armature foil respectively with the perforated andnon-perforated portions of the terminal strip inside the capacitor.

8. In the art of making capacitors including adjacent sheets of dielectric paper and L of metal armature foil, the method of anchoring terminal strips in the interior of such a capacitor, which consists in winding said' sheets in a relatively loose roll and placing a. terminal strip of which a relatively small portion is formed with a perforation, in such position inside such, capacitor that the perforated portion lies between and adjacent the paper and foil 35 capacitor sheets; and then compressing the loosely wound sheets and interposed terminal strip together under substantial mechanical pressure thereby establishin good electrical contact between the sur ace of the armature foil and the relatively large nonperforated surface of the terminal strip, and by said compression also forcing into the perforation in the terminal strip, portions of the sheets of paper and foil lying on opposite faces of the terminal strip and adjacent the perforation thereof, thereby holding the portion of the terminal strip inside the capacitor in its position adjacent the armature foil.

9. In the art of making capacitors containingadjacent sheets of dielectric paper and metal armature foil, the method of anchoring terminal strips in the interior of such a capacitor, which consists in winding such sheets in a relatively loose roll and placing a portion of a terminal strip of which a relatively small portion is formed with a break in its surface, in such position inside such capacitor that the surface-broken'porlion lies between and adjacent the paper and foil sheets; and then compressing the loosely wound sheets and interposed terminal strip together under substantial mechanical pressure thereby establishing good electrical contact between the surface of the armaturefoil and the relatively large non-broken surface of the terminal strip, and by said compression also forcing into the break in the terminal strip, the portion of the surface of the capacitor sheet which faces the surfacebreak in the terminal strip and thereby holding the portion of the terminal strip inside the capacitor ,in its position adjacent the armature-foil.

10. In the art of making capacitors including adjacent dielectric and conducting armature sheets, of which at least one is yieldable, the method of anchoring a terminal strip in the interior of such a capacitor, which consists in placing a portion of a terminal strip which is formed with a break in its surface, in such position inside such capacitor that its surface break lies adjacent said yieldable capacitor sheet; and then compressing the capacitor sheets and interposed terminal strip together under substantial mechanical pressure thereby establishing good electrical contact between the surface of the armature sheet and the terminal strip, and by said compression also forcing into the break of the terminal-strip, the portion of the yielding capacitor sheet which lies adj acent the surface-break of the terminal strip, thereby holding the portion of the terminal strip inside the capacitor in its positon adjacent the armature sheet.

11. In the art of making capacitors including adjacent dielectric and conducting armature sheets of which at least one is yieldable, the method of anchoring a terminal strip in the interior of such a capacitor, which consists in placing a portion of a terminal strip which is formed with a plurality of surface breaks located in succession in the direction of its length, in such position inside such capacitor between the dielectric and armature sheets, that the broken surface portions of the terminal strip lie adjacent at least one yieldable sheet of the capacitor; and then compressing the capacitor and inserted terminal strip together under substantial mechanical pressure thereby establishing good electrical contact between the armature sheet and the terminal strip, and by said compression also forcing the yieldable capacitor sheet into the succession of surface breaks in the terminal strip, holding the terminal strip in ing good electrical contact between the armai ture surface and the non-broken surface of the terminal strip, and by such compression also forcing into the surface-break in the terminal strip, the portion of the aper sheet 5 lying adjacent said-break, there y holding the terminal strip in place adjacent the armatime sheet against forces tending .to pull the terminal strip out of place adjacent the armature sheet.

13. In the art of making capacitors including a metal foil armature, the method of anchoring a terminal strip in the interior of such a capacitor, which consists in placing a portion of a terminal strip formed with a surface break, in such position between the armature foil and-adjacent dielectric sheet that the surface break in the terminal strip lies adjacent the armature foil; and compressing the capacitor and inserted terminal strip together under substantial mechanical pressure establishing good contact between the surface of the armaturefoil and the nonbroken portion of the surface of the terminal strip, and by such compression also forcing into the surface break in the terminal strip, that portion of the armature foil which lies adjacent said break, thereby holding the terminal strip in place against forces tending to pull it out of place adjacent the armature foil.

In testimony whereof I hereunto aflix my signature.

' BENJAMIN J. BUTLER.

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