US2048922A - Electrolytic condenser - Google Patents

Description

July 28, 1936. P. McK. DEELEY ELECTROLYTIC CONDENSER Filed June 24, 1935 R O T m V m ATTORNEY.

Patented July 28, 1936 ELECTROLYTIC CONDENSER,

Paul McKnight Deeley, New York, N. Y., assignor to Cornell-Dubilier Corporation,

New York,

N. Y., a corporation of New York Application June 24,

12 Claims.

This invention relates to electrolytic condensers and methods of making such condensers, more particularly to condensers of the socalled wet or aqueous type in which an electrode having a dielectric film formed thereon by electro-chemical treatment is mounted within a metal container or casing containing a liquid electrolyte.

The primary object of the invention is to provide an improved construction of condensers of this type, in particular an improved construction of the formed electrode or anodic member which can be economically manufactured and is efficient in operation as compared to similar devices hitherto known in the art.

According to a commonly used construction of wet electrolytic condensers, the anode is comprised of a metal sheet wound into a cylindrical spiral and mounted coaxially within a cylindrical-shaped metallic container. This and similar constructions known in the art possess the disadvantage that the electric current passing through the electrolyte has to travel from the inner center of the electrode all the way along its axial path to the outside container usually forming the negative terminal of the condenser. This long average current path through the electrolyte causes high internal resistance losses and a high power factor of the condenser.

It is an object of this invention to provide a construction of the anode or formed electrode member for wet electrolytic condensers insuring a minimum average current path between the anode member and the negative electrode, such as the metallic container of the condenser.

Another object of the invention is the provision of an anodic member adapted for use in wet electrolytic condensers which may be subjected to efficient preparatory treatment, such as to mechanical roughening or chemical etching for increasing the effective anode surface and accordingly the electrical capacity of the condenser.

Another object of the invention is the provision of a rigid anodic member of novel construction adapted for use in wet electrolytic condensers by which corrosion effects due to contact of adjacent portions of the anode surface is substantially prevented. 7

Further objects and novel aspects will appear hereinafter from the detailed description as follows taken with reference to the accompanying drawing in which:

Fig. 1 is a sectional side elevation of one construction of condenser according to the invention, and

1935, Serial No. 28,033

Fig. 2 is a cross-sectional view on a larger scale taken on line 2-2 Fig. 1.

Similar reference numerals identify similar parts in both views.

In the improved condenser according to this 5 invention, the anode consists of a flat electrode such as a metallic sheet or ribbon edgewise wound into a helix and having its ends suitably supported such as by means of a carrier and/or electrode member which passes through one end of the container and is suitably insulated therefrom. The thus obtained helicoidal electrode, while insuring a maximum effective condenser surface and maximum capacity for a condenser structure of given size and bulk, presents the further advantage of minimum length of the current path from the anode surface to the cathode or metal container thus insuring a minimum internal resistance and loss in the condenser. Preferably the carrier member for supporting the helicoidal electrode passes through a plug of a flexible insulating material such'as rubber which is held in position by pressing portions of the end of the container against it so that the plug is deformed and a liquid-tight seal obtained.

Referring to the drawing, the condenser shown comprises a metallic container I preferably of cylindrical shape and consisting of suitable metal, such as aluminum or the like. This container is preferably made in a single unit such as by' a pressing or drawing process from a thin alumlnum tube. The container has an enlarged, preferably screw-threaded neck portion shown at 4 for mounting the condenser on the support or platform in inverted position in accordance with the usual practice and as indicated in the drawing. The anodic member or formed electrode shown at 3 consists of a metallic ribbon of suitable film forming material preferably high purity aluminum being wound edge-wise into a helix to form a helicoidal surface and having its opposite ends connected to a suitable support such as a riser rod or carrier member shown at 2 disposed along the cylindrical axis of the container l. The connection of the anode 3 and the carrier memher 2 may be carried out in any well known manner such as by means of rivets shown at 6 and 'l. The rivets 6 and I should be of the same material as the anode riser rod 2, namely of film forming metal, for example, high purity aluminum. The rod 2 should also be of film forming metal such as aluminum in the example described as it too is a part of the anode member. In this manner, corrosion effects at the joints are prevented. The

carrier member 2 is passed through a resilient 55 plug 3 of relatively flexible insulating material preferably consisting-of rubber and'placed within the extending neck portion 4 of the container. The upper unthreaded part of the neck 4 is deformed such as by pressing a suitable tool against the neck in order to secure a liquid-tight and firm joint between the container, the rubber plug 3 and the carrier member 2. The anode carrier or riser rod 2 has preferably a round cross-section as shown to present a smooth surface with no sharp edges or corners and to secure a tight seal throughout the rubber insulating brushing or plug 3. Thus when the metal neck is swaged or crimped the plug will tighten around the riser rod with equal pressure in all directions, thus affording an eificient liquid tight seal. The round rod is suitably swaged or flattened at the points where the helical anode strip is riveted in place. The upper end of the carrier member 2 projecting through the plug 3 constitutes the terminal of the electrode and may be provided with a suitable connecting means, such as a clamping nut, soldering lug, etc., for connecting the condenser in an electrical circuit.

In the manufacture, the edge-wise wound ribbon 3 is first suitably treated and formed with an anodic. film and then riveted onto thecarrier member 2 as shown in the drawing. The plug 3 is then placed in position and the whole assembly mounted in the container l in a'manner a'sdescribed before. The container is then inverted and filled with suilicient electrolyte to cover the electrode but to leave space above the electrolyte level. The cover In is then placed over the open end and spun on so as to seal this end'in a liquidtight manner. If desired, a washer I I may be included in the joint between the container I and the cover i 0 so as to insure that this joint is liquidproof. This washer may consist of rubber, var-' nishes, cambric or a piece of gauze impregnated with a wax compound. Inthe latter case, the

operation of spinning over the edge of the cover will produce sufiicient heat to melt the wax so that when it cools it will seal the joint. If during operation excess heat is generated in the condenser the wax will melt or soften sufliciently to relieve any excess gas pressure and when the condenser cools the wax will harden again to re-seal is arranged'between the anode 3 and the walls of the container. To insure free access of the electrolyte to both the container and the anode surface, spacer 9 is provided with perforations of suitable size and spacing as shown in the drawing.

If the anode 3 is subjected to a preparatory toughening or chemical etching process prior to the film forming operation, such treatment should be carried out prior to the mounting or riveting of the electrode to the carrier member 2 inorder to prevent corrosion at the connecting joints and insure a tight mechanical joint.

As is obvious, the screw-like shape of the anode surface as described insures a minimum average length of the current path between the anode and the cathode members, resulting in a minimum of internal resistance and heat losses in the concontainer and being insulated therefrom, and a denser. In addition, the anode may have a sumcient thickness to allow of a sumciently deep and eflicient etching or similar surface treatment such as mechanical roughening (sand-blasting or the like) preparatory to the forming of the dielectric 5 film thereon in such a manner as to insure a maximum capacity of the condenser and a dielectric film of high electrical and mechanical properties. In addition, this construction presents a semi-rigid structure practically eliminating the 10 possibility of accidental contacts of adjacent portions of theanode surface and resultant undesirable corrosion effects during the use of the condenser. Furthermore, the construction of the invention is simple and economical in manufacture as compared with known methods and designs requiring elaborate and expensive machinery and manufacturing processes.

While I have described my invention with reference to the specific embodiment as illustrated in the drawing, I do not wish to be limited to the details thereof except as set forth in the appended claims.

I claim:

1. An electrolytic condenser having a metallic container, an electrolyte and a film forming electrode within said container, said electrode consisting of an edge-wise wound flat metallic ribbon helix, and a support for said electrode comprising a rod freely passing through the windings of said helix, the opposite ends of said helix being rigidly connected to said rod.

2. An electrolytic condenser having a metallic container, an electrolyte therein, a carrier member passing through one end of said container, and a film forming electrode consisting of an edge-wise wound ribbon helix concentrically and v freely surrounding said carrier member and having its opposite ends supported by said carrier member. 0

3. An electrolytic condenser having a cylindrical metallic container, an electrolyte therein, a carrier member disposed coaxially within said container and passing through one end of said film forming helicoidally wound flat ribbon electrode freely surrounding said carrier member and having its opposite ends supported by said carrier member. 7

4. An electrolytic condenser having a cylindrical metallic container, an electrolyte therein, a carrier member disposed coaxially within said container and passing through one end of said container and beinginsulated therefrom, and a film forming helicoidally wound flat ribbon electrode concentrically and freely surrounding said carrier member and having its opposite ends rigidly connected to said carrier member.

5. An electrolytic condenser. having a metallic container, an electrolyte therein, a film forming electrode immersed in said electrolyte consisting of a flat edgewise wound metallic ribbon helix, and a rigid carrier rod passing through an insulating bushing in a wall of said container and supporting the opposite ends of said helix.

.6. An electrolytic condenser having a cylindrical metallic container, an electrolyte therein,

a carrier-member disposed along the axis of said container and a film forming electrode consisting of a fiat metallic ribbon wound into a helicoidal 70 member, said electrode concentrically and freely surrounding said carrier member and having its opposite ends rigidly connected to said carrier member.

7. An electrolytic condenser having a metallic 75 container, an electrolyte therein, a film forming electrode immersed in said electrolyte consisting of an edge-wise wound metallic ribbon helix, and a rigid carrier member passing through and sup ported by a liquid-tight insulating bushing in a wall of said container and supporting the. opposite ends of said helix.

8. An electrolytic condenser having a metallic container, an electrolyte therein, and a filmi'orming electrode immersed in the electrolyte, comprising a carrier member disposed along the axis of said container and an edge-wise wound metallic ribbon helix concentrically and freely surrounding said carrier member and having its opposite ends rigidly connected to said carrier member.

9. An electrolytic condenser having a cathode container, an electrolyte therein, a film-forming electrode immersed in the electrolyte, comprising a carrier member disposed along the axis of said container and an edge-wise wound metallic ribbon helix concentrically and freely surrounding said carrier member and having its opposite ends rigidly connected to said carrier member, and a liquid-tight insulating bushing in a wall of said container, said carrier member being passed through and projecting outwardly from said bushing.

10. An electrolytic condenser having a cathode container, an electrolyte therein, and a filmforming electrode immersed in the electrolyte comprising a metal rod disposed along the axis of said container and an edge-wise wound flat ribbon helix of film-forming metal substantially the same as said rod, said helix freely surrounding said rod, said rod having flattened portions adjacent andconnected to the opposite ends of said helix.

11. In an electrolytic condenser as claimed in claim 10, including an insulating bushing in a wall of the container, said rod being passed through and supported by said bushing to serve as a terminal for said electrode.

12. In an electrolytic condenser in combination with a cathode container and an electrolyte therein, an anode comprising a rod supported in an upright position and centrally located relative to the container, and a continuous strip of sheetlike metal being edge-wise wound about said rod and having its opposite ends rigidly connected to said rod.

PAUL McKNIGHT DEELEY.

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