US2297608A

US2297608A - Dry electrolytic condenser

Info

Publication number: US2297608A
Application number: US193671A
Authority: US
Inventors: Blackburn Charles Marvin
Original assignee: PR Mallory and Co Inc
Current assignee: Duracell Inc USA
Priority date: 1938-03-03
Filing date: 1938-03-03
Publication date: 1942-09-29
Anticipated expiration: 1959-09-29
Also published as: GB521963A

Description

Sept' 29, 1942 c. M. BLACKBURN 2,297,608

DRY ELEGTROLYTI C CONDENSER Filed March 5, 1958 51 INVENTOR `electrode assemblies and arrangements for Patented Sept. 29, 1942 DRY ELECTROLYTIC CONDENSER Charles Marvin Blackburn, Jackson Township,

Brown County, Ind., assignor to P. & Co., Inc., Indianapolis, Ind.,

Delaware R. Mallory a corporation ot Application March 3, 19,38, Serial No. 193,671

8 Claims.

This invention relates to electrolytic condensers and particularly to electrolytic condensers of the dry type and electrodes therefor.

The present application is a continuation-inpart of my previously filed co-pending application, Serial Number 163,431, filed September 11, 1937.

An object of the invention is to improve the Udryl) electrolytic condensers.

Another object is to improve Ithe method of making the electrodes and assemblies thereof.

Other objects of the invention will be apparent from the following description and accompanying drawing taken in connection with the appended claims.

The invention comprises the features of construction, combination of elements, arrangement of parts, and method of manufacture and operalion referred to above or which will be brought out and exemplied in the disclosure hereinafter set forth, including the illustrations in the drawlng.

In the drawing:

Figure 1 illustrates diagrammatically a step in the manufacture of the condenser electrodes;

Figure 2 shows an electrode produced thereby;

Figure 3 shows an electrode which has been further processed;

Figure 4 shows a modified form of electrode;

Figure 5 illustrates one way of arranging an electrode for assembly in a condenser;

Figure 6 shows another electrode arrangement;

Figure 7 illustrates a condenser assembly prior to winding;

Figure 8 represents another assembly; and

Figure 9 is a. section through a completed condenser.

A feature of the present invention resides in the novel method of making the electrodes. Another feature is the structural arrangement of the electrodes themselves and a further feature is the method of assembly in a condenser unit.

While a preferred embodiment of the invention is described herein, it is contemplated that considerable variation may be made in the method of procedure and the construction of parts without departing from the spirit of the invention. In the following description and in the claims, parts will be identified by specific n-ames for convenience, but they are intended to be as generic in their application to similar parts as the art will permit.

In the drawing Figure 1 shows the arrangement for producing the electrode of Figure 2,

According to this arrangement a strip of cloth or gauze III or other sheet material of suitable characteristics and purity, and of appropriate width for a condenser electrode, is led over a roller Il along with a second strip I2 of cloth or gauze, or other suitable material, and two parallel narrow strips of aluminum foil I3 and I4 so that the foil strips are sandwiched between the gauze strips in spaced parallel relation.

'l'he sandwich assembly is then led over a second roller I5 and simultaneously a backing layer I6 of paper (brown paper or cheap newsprint is suitable) is led over roller I5 underneath the sandwich assembly. Paper I6 is somewhat wider than the gauze strips so as to protect roller I 5.

As the sandwich assembly led over roller I5 a deposit I8 of film-forming metal (preferably aluminum) sandwich assembly by metal spray gun I'I, commonly known as a Schoop gun, the metal being supplied to the spray gun as wire I9, melted by an Oxy-acetylene flame and sprayed onto the cloth. The gun may be oscillated back and forth across the sandwich strip during spraying, if desired, to give a more uniform deposit. Due to the porosity of the cloth or gauze the sprayed metal penetrates through the top gauze layer I0 and to some extent through the other gauze I2 where it is not protected by the narrow foil strips 3 and I4. The sprayed metal welds the foil strips to gauze I0 and, in so doing, develops a roughened or embossed surface on the back surface of the foil.

The sprayed assembly is then carried forward with all layers in contiguous relation until it cools considerably after which it passes over a roller 20 where the paper backing I6 is carried off and the gauze backing I2 is also stripped away from the front gauze I0 and foil strips i3 and I4. Gauze I2, which has some metal deposited in it. 1s wound up in a roll and can subsequently be used for the front gauze in making another electrode.

Prior to the spraying operation a plurality of flattened aluminum terminals 2l are fastened to gauze l0. Terminals 2l consist of lengths of wire which have been flattened for part of their The flattened part is laid across the cloth or gauze strip and a plurality of holes are punched in the flattened portion so that the burr raised on the cloth-contacting side by the emergence of the punch projections extends through the layer of cloth. The assembly is then rolled to flatten down the burr onto the cloth and thus rivet the terminal thereto. In spraying the terhaving a spray-deposit A nlm-forming metal) on one side thereof and more minal becomes spray-welded to the gauze along with the foil strips.

The resulting electrode is shown in Figure 2. It comprises a single layer of cloth or gauze Il I8 of aluminum (or other or less distributed through the layer, a pair of parallel foil strips I3 and Il integrally bonded to the cloth layer by the sentng a more or less embossed outer surface, and a iiattened terminal riveted and spray-welded to the cloth.

The terminals 2i can beattached at any desired spaced intervals along the cloth strip prior to spraying and after spraying the nished electrode may be cut to the required length, leaving one or more terminals in each cut electrode strip. The terminals may be at the end or ends of the strip or at an intermediate point. It is also contemplated that the terminals may be attached after spraying, if desired.

The sprayed electrode, preferably before cutting into lengths, may be film-formed by passing through a suitable bath of film-forming electrolyte while applying A. C. or D. C. potential between the electrode and the tank.

Two or more of the electrodes thus formed may then be wound up with interposed porous sheet spacers of paper, cloth, regenerated sheet cellulose or other spacer materials suitable for dry electrolytic condensers and impregnated with a suitable dry electrolytc condenser electrolyte, such as one of those mentioned in my prior-filed co-pending application, above identied. Due to the porosity of the spray-deposit, which is further enhancedby the gauze base, the electric capacity of the condenser is several times that of a similar unit made of aluminum foil of the same dimensions. The electrolyte used for impregnation is absorbed by the electrode gauze as well as by well as the front surface of the spray-deposit, is effective for increased capacity. The foil strips I3 and I4, while serving principally to maintain a good electrical circuit longitudinal to the electrodes, also contribute to the electric capacity, and due to the embossing or roughening of the exposed surface from the spraying operation, the capacity is still further increased. Such a condenser is suitable for A. C. or D. C. uses. When used for D. C., the cathode may be` of foil instead of sprayed gauze, if desired.

spray-deposit and pretageously be used in multiple layers in forming condenser electrodes. That is, instead of using a single electrode strip for an electrode, as has heretofore been the practice, two or more strips are placed face-to-face and their terminals connected together. I have found that the electrode produced from two strips put together in this manner has substantially twice the effective capacitance of a single strip. Three strips give three times the capacitance, etc. This is due to the fact that the layers are porous and when impregnated with electrolyte permit a current path through the electrolyte to all parts of the several layers. The series resistance, due to the longer current path through the electrolyte, is increased somewhat by this arrangement but is Well within acceptable commercial limits.

It will be noted that by this expedient, using a double electrode, only half the length of spacer material is required of what was formerly necessary. And where the condenser is intended for D. C. uses, in which case the cathode plate may be a single thickness of foil or sprayed gauze, the amount of cathode material required is correspondingly reduced.

Figure 5 illustrates a preferred method of producing this construction. This comprises folding the electrode of Figure 2, 3 or 5 back upon itself to form the double layer, the fold preferably being made near the tab 2 I The foil strips I3 and I4 should preferably be on the inside.

Figure 6 illustrates how three electrode strips might be placed face-to-face and attached together by their terminal tabs 2l, which are riveted or punched together at 25.

the spacers and hence the back, as

According to a modication the electrode of y Figure 2 is run through the spraying process a second time with the foil side nearest the spray gun. This applies a spray deposit to the exposed surface of the foil strips and adds further sprayed metal to the gauze, thereby giving a still higher capacity. The modified electrode thus produced is shown in Figure 3. Another advantage in this electrode resides in the fact that the foil is covered on both sides with sprayed aluminum and hence a lower purity foil can satisfactorily be used than would be required where the foil itself is in contact with the electrolyte.

Figure 4 shows another modification in which a pair of narrow strips of

foil

22 and 23 are laid in staggered relation on the two faces of a strip of gauze 24 and the assembly is sprayed on both sides to form an 'integral electrode. The thin aluminum foil is simultaneously embossed by the spray in the design of the cloth backing.

I have discovered that the electrodes above described, as well as those disclosed in my above identified copending application, may advan- Figure I shows a D. C. condenser assembly 4made up using the electrode of Figure 5 as an anode with a foil electrode 26 (having terminal 21) as a cathode and spacers 28 of paper, cloth or other suitable material, laminated if desired, between the anode and cathodes. The assembly can be rolled up, impregnated with electrolyte,

and inserted in a suitable can according to weilv known procedure. Due to the multi-layer nature of electrode I0 it is more flexible than a. single thick layer would be and the individual layers will slide on each other during winding. Hence undue bre stresses and resultant cracking are avoided.

In some cases it is desirable to make a condenser having a common cathode and two or more anodes, one of which is required to be of only small capacity and which serves as an audio byfpass condenser in certain circuits. Because of the extremely large capacities per unit area obtained with sprayed electrodes a very small section of electrode strip would be required for this by-pass condenser. While it is feasible to use such a section it introduces some mechanical handling diiiiculties. I have found that it is of advantage to use a piece of plain or etched aluminum foil for the smallcapacity unit. The'- amount of foil required, while greater than the amount of sprayed gauze which would be necessary, is still very little. Moreover the use of foil gives a somewhat better power factor on these smaller units.

Figure 8 illustrates a condenser assembly comprising an anode I0 of sprayed gauze, a second anode 30 of foil, and a common cathode 32 of foil separated from the anodes by spacers 33. Instead of common cathode 32, two foil cathodes can be used, one Opposite each anode.

It is preferred that the assembly be wound by starting at the right-hand end as indicated by the arrow. It will be noted that this rolls electrode I so that its top sprayed surface 34 is on the inside of concave face of the turns. This tends -to press the particles of sprayed metal to.- gether and insure the highest conductivity parallel't'o the sheet. This is of particular advantage with the electrode of Figure 2 wherein only one side is sprayed.

Figure 9 shows a completed condenser comprising a can 39 containing a roll 35 produced by rolling up the assembly of Figure 8. Anode terminals 2| and 29 are brought up through insulating top 36 and provided with lugs 31 and 38, and the cathode terminal is inserted between the top and the can and spun under the edge of the can.

While the present invention, as to its objects and advantages, has been described herein as carried out in specific embodiments thereof, it is not desired to be limited thereby but it is intended to cover the invention broadly within the spirit and scope of the appended claims.

What is claimed is:

1. An electrode for dry electrolytic condensers comprising a layer of brous material, a terminal riveted thereto, and a deposit of hlm-forming metal on and in said fibrous layer, saidfspraydeposit also bonding said terminal thereto.

2. An electrode for dry electrolytic condensers comprising a strip of cloth, a metal terminal strip laid transverse of said-cloth strip and attached thereto .by integral upset metal projections, and a spray-deposit of film-forming metal on and in said cloth and further bonding said terminal thereto.

3. 'I'he method of making an electrode for dry electrolytic condensers which comprises securing a terminal strip across a strip of brous sheet material by punching through said terminal strip and said fibrous strip and flattening the projections thus produced on said terminal once onto said brous sheet surface, and then spraying a deposito! nlm-forming metal onto said fibrous sheet.

4. The method of 'making an electrode for dry electrolytic condensers which comprises running together two strips of cloth with at least one narrower strip of metal sandwiched therebetween, spraying a deposit of film-forming metal into one side of the sandwich assembly whereby said metal strip is bonded to the cloth which is4 directly exposed to the spray and subsequently stripping oil the cloth not directly exposed to the spray, and then spraying the foil side of the cloth strip to which the foil is attached.

6. An electrode for dry electrolytic condensers comprising a pair of layers of open-mesh brous sheet material and a spray-deposit of film-forming metal thereon and therein, said layers being disposed in face-to-face pressure contact and joined by a folded edge, and a terminal connected thereto.

7. 'I'he method of making an electrode for dry electrolytic condensers which comprises placing a thin aluminum foil against a backing having a multiplicity of closely spaced raised portions separated by depressions and spraying the exposed surface of said foil with a deposit of alu minum to simultaneously emboss said foil and attach said deposit thereto.

8. The method of making an electrode for dry electrolytic condensers which comprises placing a thin aluminum foil against a backing having a multiplicity of closely spaced raised portions separated by depressions, placing a layer of cloth over said foil and spraying a deposit of aluminum into said cloth and against said foil to simultaneously emboss said foil and attach said sprayed aluminum to said foil and said cloth.

CHARLES MARVIN BLACKBURN.