US2199446A - Electrolytic condenser - Google Patents

Description

Filed Oct. 26, 1937 INVENTQR f 'amuei 15915211 ATTORNEY Patented May 7, 1940 UNITED STATES PATENT OFFICE 10 Claims.

This invention relates to electrolytic condensers. A general object is the provision of electrolytic condensers of both dry and wet type which are of new, novel and simpledesign, which can be produced-at a low cost, which provide maximum capacitance for a given volume and which to a large extent may be manufactured by machine with a minimum of labor.

An object of the invention is the provision of an electrolyticcondenser in which the anode, cathode and spacer are combined in a unitary structure.

A further object is the provision of an electrolytic condenser in which both electrodes. and the spacer are united in a single .woven cloth.

Another object is the provision of a unitary electrolytic cell structure composed of a woven cloth, the shoot of which is insulated from the warp.

Still another object is to provide a unitary cathode-anode spacer structure by weaving together two metal strands insulated from each other by a porous spacer wound around at least one of said strands.

5 Another object is the provision of an electrolytic device having two or more capacitances in a single unit.

A further object is to provide a multi-capacitance condenser in the form of woven cloth having a plurality of separated warps serving as anodes in relation to and electrically insulated from the shoot strands, serving as a common cathode.

Further objects will be apparent from the disclosure and from the drawing, in which,

Fig. 1 is a face view of a unitary cathode-anode spacer construction made according to this invention;

Fig. 2 is a view showing in detail the arrange- 40 ment of cathode, anode and spacer;

Fig. 3 is a face view of a structure which comprises two capacitances'in a single unit;

Fig. 4 is a view ofthe structure shown in Fig. 1 in semi-rolled form, and

Fig. 5 shows a condenser mounted within a container.

Dry electrolytic condensers as heretofore commercially. manufactured comprise two cooperating electrodes of film forming metal such as -5o aluminum or tantalum, at least one of the electrodes having electrolytically formed on its surface an immeasurably thin film of oxide which serves as the dielectric. The electrodes are separated by absorbent spacers such as gauze, paper, 55 non-fibrous sheet cellulose or combinations of these spacers, and the electrolyte employed is a viscid film maintaining composition which may be a heavy paste, or only slightly viscous. As the condensers are usually constructed in roll form, at least two spacers are required in order to prevent short-circuiting of the electrodes. Thus, the manufacture of the condenser requires the handling of two rolls of foil and two or more rolls of spacer, such as Cellophane, paper, gauze, et cetcra. If the condensers are wet Wound, 10 that is, if the foils and spacers are drawn through the viscid electrolyte in the winding process, difiiculty is sometimes encountered in lining up the rolls and in preventing telescoping. If the condensers are dry wound and thereafter im- 5 pregnated with the electrolyte, the tight winding of the foils and spacers retards the absorption of the viscid electrolyte by the spacer and makes necessary a long immersion period and in some cases, a centrifuging operation. 20

In my co-pending application bearing Serial Number 162,401, filed September 4, 1937, of which this application is acontinuation in part, I describe the use of woven metal cloth as an electrode in order to obtain a high capacitance in a small area. I also describe in that case, a structure comprising a cloth woven from cotton-covered aluminum wire, the cotton winding allowing an increased effective area and capacity and eliminating the use of separate spacer elements. 30

In the present invention I utilize-cloth having a weave somewhat similar to that shown in my aforesaid co-pending application, but go a step further and provide cathode, anode and spacer in a single woven structure. In this new condenser 35 the shoot may be composed of electrolytically oxidized aluminum wire which serves as the anode and the warp may be composed of double cottoncovered aluminum wire, or the warp may be the anode and the shoot the cathode. The two strands are woven into a close mesh cloth, preferably in ribbon form, about two inches wide with a selvage edge. The anode threads should be very closely spaced in order to aiford the maximum eifective area.

The warp may to advantage be composed of large diameter wire when the unit is used on direct current. For example, I have used as warp strands .010 inch diameter cotton-covered aluminum wire, which strands serve as the cathode, and for the anode or shoot wire I have used .005 inch diameter aluminum with a 200 x24 twill weave. In some cases a plain weave is desirable, while in other cases a twill weave is of advantage.

If the condenser is to be used on alternating combination of paper and Cellophane",

current, the warp and the shoot are both electrolytically oxidized or formed and are 0! equal area so as to avoid assymetrical conductive effects.

The manufacture of the condenser section is exceedingly simple, the woven ribbon being merely wound into roll form and immersed in the electrolyte.

While aluminum wire is considered the most suitable film-forming material, other metals, such as tantalum, magnesium or alloys of these metals with aluminum, may be utilized. I prefer to form oroxidize the wire prior to the time it is woven into the cloth, but the forming may, of course, take place after the weaving. To increase the capacitance of the unit the wire prior to forming, may be etched in a manner well known to the art, for instance, by immersing in a bath of copper-chloride or in a mixture of hydrofluoric and hydrochloric acids.

Cotton is the preferred material for use as a spacer element and as an electrolyte-absorbing material but other spacers capable of being wound or wrapped upon the wire may be used, for example, Cellophane, paper, rayon or a cemented together with a. conductive cement. The cotton-covered wire may, i-fdesirable, be sized with methyl cellulose plasticized with a glycol, thus providing a film between the cotton fibres, having properties somewhat akin to Cellophane.

While in most cases it will be desirable to cotton-cover only one of the electrodes, namely, the warp, both the warp and shoot may be advantageously covered for some purposes. Where both electrodes are covered, the maximum quantity of electrolyte is held in contactwith the electrodes. are cotton-covered, plain thin aluminum foil can with advantage be used in contact with each side of the cloth in order to reduce the current path length and thus maintain a low power factor. Such a sheet of foil can also be used to advantage on direct current condensers where the anode is a cotton-covered shoot and the cathode is the plain aluminum wire warp. In the latter structure the foil would be connected to the warp.

Where it is desired to provide diiferent values of capacitance in the same unitary condenser structure, the warp or the shoot may be utilized as a common cathode. mon cathode, the selvaged edge with the shoot or bare wire is cut and several strands of the shoot wire pulled out, thus electrically-separating the shoot weave. Contact is made with the shoot wires brought out from the various separated sections, thus allowing a simple and economical method of obtaining multi-capacitance units.

The structure may also be used for polarized cells ofthe iron or nickel type, employing alka- If the warp is the com-.

Where both warp and shoot wires line electrolytes which operate below the decom-' position potentials of the electrolyte.

In order to more fully describe certain forms of the invention, reference is made to the attached drawing. In Fig. 1, the unitary structure I, comprising the anode, cathode and spacer, has been partly cutaway at one end section to provide anode tab 2, and at the opposite section cathode terminal post I, which serves as the common cathode for anodes I. and 'b.

While the invention is especially useful in connection with dry or plastic-type electrolytes of the type described in my United States Letters Patent 1,710,073; 1,714,191; 1,891,207; 1,918,716; 1,918,717, et al., the structures shown or modifications thereof may be advantageously used in wet electrolytic condensers, especially where it is desired to provide two or more capacitances in a single unit. For instance, the structure shown in Fig. 3 may be modified to substitute enameled copper wire for the cotton-covered aluminum cathode 3, the enameled insulation being removed at the terminal of the wire to provide contact with terminal member 4 and the electrolyte.

Fig. 4 shows the condenser structure of Fig. 1 in semi-rolled form.

InFig. 5' a condenser section III, comprising the structure illustrated in Fig. 1 in roll form has been impregnated and wrapped with varnished paper II, and mounted in container l2, from which it is insulated by pitch l3. The container' is sealed by Bakelite top l6, through which are brought out terminals l4 and I5.

The structure of the condenser lends itself readily to a simple impregnation process. Due to the unitary structure, no difflculty is experienced in thoroughly impregnating every part of the condenser, and due to the close association of the spacer element with the film-forming electrodes a maximum quantity of electrolyte is always in contact with both cathode and anode. This is, of course, particularly true when a viscous fluid electrolyte of the glycol-ammonium .borate type is used. As not only is this type of electrolyte thoroughly absorbed .in the cotton spacer, 'but due to its viscous character and the woven surface of the cathode-anode structure, it tends to adhere to all parts of the condenser unit.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. An electrolytic 'condenser comprising an aluminum cloth, the shoot constituting one electrode and the warp the other electrode, a spacer around' at least one of said electrodes so as to insulate it from the other electrode, and an electrolyte.

2. An electrolytic condenser comprising a metal cloth, said cloth comprising metal wires at least one of which is a film forming metal, the shoot constituting one electrode and the warp the other electrode, a spacer around at least one of said electrodes so as to insulate it from the other electrode, and an electrolyte in said spacer and in contact with both electrodes.

3. An electrolytic condenser comprising a metal cloth, the shoot constituting one electrode and the warp constituting the other electrode, an electrolyte permeable cellulose spacer around at least one of said electrodes so as to insulate it from metallic contact with the other electrode,

and an electrolyte in said spacer in contact with both electrodes.

4. An electrolytic condenser comprising a metal cloth, the shoot constituting one electrode and the warp constituting the other electrode, an electrolyte permeable cellulose spacer around at least one of said electrodes so as to insulate it.

forming metal wire being chemically etched so as to increase its capacity and having a dielectric oxide film formed on said etched surface, a spacer around at least one of said electrodes so as to insulate it from metallic contact with the other, and an electrolyte in said spacer and in contact with both electrodes.

6. An electrolytic condenser comprising an aluminum cloth, the'shoot constituting one electrode and the warp the other electrode, at least one of said electrodes comprising film forming metal, an electrolyte permeable cellulose spacer spirally wound around at least one of said electrodes so as to insulate it from metallic contact with the other, and an electrolyte in said spacer and in contact with both electrodes.

7. An electrolytic condenser comprising a metal cloth, the shoot constituting one electrode and the warp the other electrode, atleast one of said electrodes comprising a film forming metal etched to increase the eflective surface area I thereof, a dielectric oxide film formed on said etched electrodes, an electrolyte permeable cellulose spacer wound spirally around at least one of said electrodes so as to insulate it from the other electrode, and a viscous film forming electrolyte impregnating said condenser structure. 8. An electrolytic condenser comprising a woven metal cloth immersed in an electrolyte, one set of parallel strands of said cloth comprising the cathode, and a plurality of sets of parallel strands transverse to said first set comprising anodes, an insulating spacer directly spirally wound around at least one set of parallel strands so as to insulate it from metallic contact with the said transverse strands, an electrolyte in said spacer and in contact with said cathode and anodes.

9. An electrolytic condenser comprising a woven metal cloth immersed in an electrolyte, one set of parallel strands of said cloth comprising the cathode, and a plurality of sets of parallel strands transverse to said first set constituting anodes, a coating on said cathode strands to insulate said cathode from the anodes, and an uninsulated portion of said cathode not in contact with said anodes but in direct contact with said electrolyte. 10. A dry electrolytic condenser comprising a container having therewithin an aluminum cloth, the shoot constituting one electrode and the warp anotherelectrode, a spacer around at least one of said electrodes so as to insulate-it from said other electrode, and a viscous electrolyte.

SAMUEL RUBEN.

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