US2220887A - Electrolytic condenser - Google Patents

Description

Nov. 12, 1940. A. F. P. J. cLAAssEN ELECTROLYTIC CONDENSER Filed Feb. 10, 1938 Patented Nov. 12, 1940 UNITED- STATES PATENT OFFICE ELECTROLYTIC CONDENSER Application February 10, 1938, Serial No. 189,87d In Germany February 13, 1937 1 Claim.

My invention relates to electrolytic con densers, and moreparticularly to condensers in; which the electrodes are rolled, wound or folded together with the interposition of an electrolyte 5 absorbing material to form a condenser unit which is housed in a container.

So-called dry" electrolytic condensers, i. e. condensers in which a dry or pasty electrolyte is carried by an absorbent layer which acts as a spacer betwen the electrodes, have the advantage that .the series resistance is low because the distance between the electrodes is generally small and of the order of about 0.15 to 0.3 mm. In such condensers the electrolyte cannot freely flow so as to reach a breakdown point, and as a result the self-healing eifect of such condensers is appreciably reduced.

In contradistinction to dry condensers, wet

- electrolytic condensers have the disadvantage that the series resistance is increased at cer tain points of the anode surface, and consequently the power factor of the condenser may become unduly high. More particularly in such condensers the cathode generally forms the container, and as the anode surface, aiter it has been formed, determines the capacity of the con-=- denser this surface is generally made as large as possible, for instance by giving it a star shape, or by forming the anode of a spirally-wound band. As a result the distance from the cathode through the electrolyte to the anode varies for diii'erent'points on the anode. Furthermore, in such condensers the series resistancais more or less dependent upon the temperature. On the other hand, wet electrolytic condensers have th advantage that they are self-healing to a high degree.

The object of my invention is to eliminate the above disadvantages and to producean electrolytic condenser which has all the advantages has none of their disadvantages.

Another object of my invention is to produce an electrolytic condenser, which is self-healing to a high degree, and has a series resistance which is low and independent of temperature to a high degree.

Further objects of my invention will appear as the description progresses.

In accordance with the invention I use peri'orated electrodes, which are wound, rolled or stacked". with the interposition of an absorbent layer, and provide the condenser with a supply of a liquid electrolyte.

with such a construction the condenser not of both dry and'wet electrolytic condensers, but

only has a very low series resistance due to the close spacing of the electrodes, but also is selihealing to a high degree because the liquid elec trolyte can readily reach all portions of the filming surface. This admission of the electrolyte is further improved by the fact that there will be spaces between the electrodes and the spacers as the unit is very loosely wounded.

In this way practically a wet condenser is obtained, however the advantages of the dry condenser are maintained in so far that the unit is obtained by winding electrodes in the form of foils separated by a spacer together to a. unit.

In order that my invention may be clearly un-- derstood and readily carried into effect, I shall describe the same more fully with reference to the accompanying drawing, in which:

Figure 1 is a partly-sectionized view of an elec-= trolytic condenser according to the invention; and

Fig. 2 is an enlarged view along line 22 of Figure 1.

The electrolytic condenser illustrated in the drawing comprises a cup-shaped metal container 8, whose upper end is provided with a pro tuberance H. Secured to the lower end of the container in a liquid-tight manner by means of gasket Ill, for instance of rubber, is a member t oi. insulating material having an externallythreaded projecting portion H which serves to secure the condenser to a panel.

Rlveted to member 4 is a supporting rod I provided with an axial slot IS. The bottom end of rod i is provided with a flange 3 having a corrugated surface bearing upon gasket ID to efiect a liquid-tight. seal. A lug 6 is riveted under the end of pin l at5 and serves as an anode connection for the condenser.

To allow for the escape of gases developed within the container during Operation, a rubber band i3 encircles protuberance II to normally close apertures It provided .therein.

Supported by rod I is a condenser unit or roll B comprising an anode I! and a cathode i8 in the form of metal strips, for instance of alumi- 5 num, provided with a large number of apertures 20. Between anode I! and cathode l8 are strips i6 of liquid absorbent material, such as cotton fabric.

stood to mean that the winding is so eflected that the distance d between the anode l1 and cathode l8 varies generally between the thickness 13 of the spacer l6 and two to about three times the thickness t. Of course there will be places in the unit where the cathode and anode are in direct contact with the spacer, and where the distance between them is therefore equal to t. The winding is eflected however so loosely, that at other places the distance may be even about three timw the thickness t.

The anode i1 is provided with a dielectric film which may be formed either before or after it is wound into the roll. As shown in Fig. 1, the cathode I8 is provided with a lip 1 which is secured to container 8 at A, for instance by spotwelding. The container is filled to a level above the roll B with a suitable liquid electrolyte I9, such as a solution of 20 grams of borax' and 40 grams of boric acid per liter of water.

It will be noted that because of the loose winding of the electrodes and the presence of apertures 20, the electrolyte can readily reach all portions of the filming surface and thus the condenser has high self-healing properties. Furthermore, because of the use of cathode strip is and anode strip I1, and because these strips are spaced apart at distances which are small and substantially constant the series resistance of the condenser is very low and does not vary to a large degree with temperature.

While I have described my invention in conand forming a space between the side of the unit and the wall of the container, said unit comprising two large surface-area members acting as an anode and a cathode respectively and both being provided along substantially their entire length with a large number of perforations, and layers of porous material between said members. said members and layers being loosely wound into a compact unit with the distance between adjacent surfaces of the members varying between one to three times the thickness of the interposed porous layer and with spaces existing between the layers and members at some points of the unit, a liquid electrolyte filling the space between the unit and the container, the perforations and the spaces between the layers and members, a conductor connected to one of said electrode members, and a second conductor connected to the other electrode member and supporting said unit from the container.

ANTHONY FREDERIK PETER JOHANNES CLAASBEN.

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