US2776467A - Method of making a closure and terminal construction for electrolytic devices - Google Patents

Description

Jan. 8, 1957 J. B. BRENNAN 2,776,457

METHOD OF' MAKING A CLOSURE AND TERMINAL CONSTRUCTION FOR ELECTROLYTIC DEVICES Filed Nov. 27, 1951 1N VEN TOR.

Joss/PH 5. BKE/Y/VHN ATTORNEYS nited States METHOD F MAKING A CLOSURE AND TEAL CNSTRUCTION FR ELEC- TROLYTC DEVICES This application is a continuation-impart of my c0- pending application Serial No. 558,864 filed October 16,

i944 now abandoned.

This invention relates to electrolytic devices and more particularly to a method of making a closure and terminal assembly for electrolytic devices such as electrolytic condensers, rectiilers, lightning arrestors and the like.

Such devices frequently comprise two or more elecrodes immersed in an electrolyte disposed within a thin walled metallic container' such as a thin Walled, drawn or extruded aluminum cup or can having one open end. lt is necessary to prevent leakage of the electrolyte from the containers and at the same time to provide for terminal connections of the electrodes. F[be terminals must extend to the exterior of the containers and ordinarily must be insulated from each other and from the container. Heretofore, it has been difficult to provide permanently leak-proof assemblies, for pressure alone has been relied on for sealing :and pressure sealing often is not lealsproof against the capillary action and crystal growth encountered in devices such as electrolytic condensers.

A general object of the present invention, therefore, is to provide a method of making a simple and inexpensive closure and terminal assembly for such devices. Another object is the provision of a closure and terminal assembly which will remain leakproof in service.

Another object is to provide a method of making such an assembly wherein the terminals are spaced from each other and from the container, and supported in their spaced relationship by the closure member.

Still another object is to provide a method of making such an assembly with inexpensive materials and rapidly.

A further object is to provide a method of making a terminal and closure assembly which will be permanently leakproof and in which the terminals and container are positively spaced and electrically insulated from each other.

Further objects and advantages of my invention will become apparent from the following description of preferred forms thereof, reference being made to the accompanying drawings in which: y

Figure l illustrates an electrolytic device such as a condenser or the like embodying one form of my invention, the upper part of the device being shown in section to illustrate my closure and terminal assembly;

Figure 2 is a section as indicated by line 2--2 of Figure l and showing the underside of the closure and terminal assembly;

Figure 3 is an enlarged, fragmentary detail of the seal between the closure member and the container;

Figure 4 is an enlarged sectional detail showing one of the terminal members supported in the closure member;

Figure 5 is a View similar to Figure l but illustrating a slightly modified form of my invention;

Figure 6 is lan enlarged sectional detail through one of the terminal members of Figure 5;

' atent 1 Figure 7 is a similar sectional detail of a modified form of terminal member for the assembly shown in Figure 5;

Figure 8 is a View similar to Figure l, but showing a still further modification or" my invention;

Figure 9 is a plan view of the assembly shown in Figure S as indicated by the line 9-& of Figure 8;

Figure lll is exploded view showing the parts making up the closure and terminal assembly of Figure 8; and

Figure ll is an enlarged sectional detail of the assembly illustrated in Figure 8, showing one of the terminal members.

Briefly, my invention, in its preferred forms, contemplates the provision of a closure and terminal assembly for thin walled metallic containers comprising a closure member preferably in the form of a disc composed of a suitable insulating material, the periphery of the disc being joined or cemented to the container, preferably by a ieakproof plastic bond such as the bond produced by the cycleweld process. rlhe disc is provided with as many openings as there are terminals. These openings in the insulating discs are closed by metallic discs or cups or shoulders which are cemented to the insulating disc in leakproof relationship, and the terminal members are welded, soldered or otherwise suitably secured to the metallic discs. l may provide, for example, an internal terminal member extending from one electrode of the electroyltic device to the inner side of one of the metallic dscs, the exterior of the metallic disc being connected to an external circuit through an external terminal member welded, soldered or otherwise secured to the exterior of the same dis-c. Thus an entirely lealtproof connection is provided, the terminal members are supported in the desired positions by the disc of insulating material to which the metallic discs are secured, and the internal and external terminal members may be made of materials best suited for their respective duties,

In Figures l to 4 of the drawings I have shown one form of my invention as adapted to an electrolytic device such `as an electrolytic condenser comprising an electrode assembly indicated diagrammatically at itil, immersed in an electrolyte 11 within a thin Walled aluminum container l2. The aluminum container l2 is open at its upper end and is deformed inwardly as shown to provide a shoulder r1.3 adapted to engage the underside of the insulating disc i4. The periphery of the disc i4 ts closely within the wall l5 of the container l2, and the upper edge of the container is pressed, rolled or spun inwardly as at i6 thereby retaining the disc l in position.

The disc i4 may be composed of any suitable insulating material. Hard rubber, ber, glass, porcelain or other ceramic material, various plastics, and other natural or synthetic insulating materials are suitable. For example, l may use discs composed of plastics such as resins of the phenol formaldehyde, urea formaldehyde, styrene, ethyl cellulose and vinyl types. The resins may be used either With or without iiber or fabric reinforcing materials. Hard ber discs coated with a plastic bonding material may be employed. The selection of the particular insulating material will depend upon the service to which the device is put. the nature of the electrolyte and the cost of various materials. For most purposes discs composed of resins of the phenol formaldehyde type are extremely satisfactory. Glass, porcelain or ceramics may be employed where cost lis an important consideration and Where there is little likelihood of shock or rough treatment.

In order to secure the disc in place with a permanently leakproof joint which also has high mechanical strength, l preferably cement the disc to the inner surface of the container 12. This cementing or bonding operation is preferably carried out by the process known as cyclewelding and developed by Chrysler Corporation. According to this process the cementing medium, which is a thermosetting plastic material, is applied to the surfaces to be joined by brushing, spraying or dipping, is permitted partially to dry and then the assembled parts are subjected to heat and pressure to vulcanize or otherwise cure the cementing material, producing a permanent bond which has ample strength and which adheres to both the metal and the plastic or other insulating material so strongly that a permanent bond is produced which is not destroyed by differences in expansion of the parts due to variations in temperature.

Other bonding materials may be used in place of the cycleweld cement. The bonding material selected should adhere strongly to the container and to the insulating disc. This result is ordinarily obtained, i believe, by providing cement that has high penetration, that is, cement which will penetrate and thus adhere to the minute pores of the surfaces to which it is to be joined. Also, after curing, the cement should not react with or be soluble in the electrolyte. Thus, after curing, cements intended for use in electrolytic condensers should not be soluble in or react with water, various alcohols and solutions containing borax and boric acid. Also the material, after curing, should be free from chlorides, or at least should be of such nature that it will not give olf enough chlorides to contaminate the electrolyte. In the case of electrolytic condensers, the cured cement or bonding material should have the ability to stand temperatures of from 80 to 90 C. for long periods of time without substantial deterioration. Preferably, the cured bonding material should be an insulator so that the bonding material itself would not furnish a conductive path in the event some of it should be spilled on the surfaces of the insulating discs.

By such a bonding method, the insulating disc is permanently joined to the aluminum container, and because of the relatively low cost of materials and the rapidity of the operation, the bonding operation can be carried out very economically. The resulting bond is indicated diagrammatically in Figure 3 wherein the plastic bonding material is shown diagrammatically at 17 as extending be- 'tween and bonding together the cylindrical surface and adjacent lower and upper surfaces of the disc 14, and the inner cylindrical surface of the wall 1S, the upper surface of the shoulder 13 and the undersurface of the ange 16 of the container 12. The thickness of the bonding material .is necessarily exaggerated throughout the drawings. In making this assembly, the parts are coated with the bonding material which is then oven dried or permitted to dry in the air to the proper degree. Then the disc 14 is assembled with the container and the flange 16 which originally was of cylindrical form, is rolled or spun into engagement with the upper surface of the disc as shown in the drawing. The spinning operation supplies the required pressure to the bonding material and accordingly with this type of assembly, the final curing or vulcanizing operation can be carried out merely by the application of heat to the bonding material. Thus the equipment necessary to complete the bond is simplied, for the vulcanizing operation may be carried out merely by applying the necessary heat to the exterior surfaces of the container adjacent the bonded areas by means of a simple heated metallic collar, for example.

In order to connect the electrode assembly to au external circuit, terminal members are required for each separate electrode in the assembly. In the pesent instance, I have shown the electrode assembly as having two terminal members 26 projecting therefrom. Such an arrangement would be used with an ordinary electrolytic condenser having an anode and a cathode. However, it is to be understood that in some instances, it may be necessary to provide more than two terminal members, and in others, only a single terminal member may be required.

In order to connect the internal terminal members 20 with an external circuit, each terminal member 20 is welded, soldered or otherwise suitably secured to a metallic disc 21. Each disc in turn is secured as by the cyclewelding or other suitable process to the insulating disc 14, preferably by bonding or cementing the metallic discs to the interior surface of the insulating disc as shown. The insulating disc is apertured adjacent the discs 21 as indicated at 22, to permit the external terminal members 23, which are welded, soldered or otherv/ise secured to the outer sides of the discs 21, to pass through the disc 14. The assembly is shown on an enlarged scale in Figure Here the internal terminal member 20 and external terminal member 23 have their end portions 24 and 25 bent parallel to the disc 21 and disposed on opposite sides of the disc so that both end portions can be secured to the disc by a single spot welding operation, producing the aligned spot welds indicated diagrammatically at 26 and 27. The cementing material for securing the disc 21 to the disc 14 is shown diagramamtically at 28.

In an electrolytic condenser, the internal terminal members and the metallic discs are preferably composed of aluminum or other film forming metal. inasmuch as it is diflicult to make a soldered connection to aluminum, the external terminal members are preferably composed of a metal which can be soldered easily such as copper or tinned steel. Thus, the internal terminals and discs may be composed of materials which will not contaminate the electrolyte or cause leakage in the condenser, and the welded joint between these parts insures that the connection will be of low resistance and Will not deteriorate. The exterior terminals may be made of material best suited to their particular function, for they do not enter the interior of the condenser in any way, and hence no consideration need be given to any possible reaction with the electrolyte.

By this arrangement, I have provided a simple and -leakproof assembly which can be manufactured economically and rapidly. I prefer to provide the disc 14 with openings 22 before assembly with the other parts. The terminals 20 and 23 are welded to the discs 21, making a sub-assembly, then discs 21 are secured to the disc 14. Thereafter the various elements of the condenser are assembled and finally the operation of securing the disc 14 within the container 12 is carried out. 'Ihis operation can be carried out without subjecting the device to excessive heat and without disturbing the assembled relationship of the parts. In the completed structure, the internal and external terminal members are rigidly spaced from each other by the disc 14 and are insulated from each other and from the container 12 by the disc 14. The bonding material itself is also an insulator. There is no possibility of leakage, for the openings in the disc 14 are completely closed by the discs 21. Obviously, various types of terminal members can be employed. In some types of devices, the terminals may be soldered or brazed to the discs 21 instead of being Welded as shown herein. If desired, the discs 21 may be secured to the exterior of the disc 14 with the inner terminal member 20 extending through the openings 22. In such an arrangement the external terminal members 23 might be omitted, external connections being made directly with the discs 21 by spring contact ngers or other suitable means.

In the modification of my invention shown in Figures 5 and 6, all of the parts, with the exception of the discs 21, are substantially identical with those previously described and have been marked with the same reference characters. In this modification, however, instead of using flat discs for sealing the openings in the disc 14 and interconnecting the internal and external terminal members 26 and 23, I employ drawn cup-shaped members 21a. The end portions 24 and 25 of the terminals 20 and 23 are spot Welded or otherwise suitably secured to the bottom portions 29 of the cups, and the cups have cylindrical portions 30 which fit closely within the openings 22 in the disc 14. The cups, which can be manufactured economically on cyclist-making machines, are preferably provided with flanges 31 at their closed ends, and are hanged over as at 32 after they have been assembled with the disc 14. The cement or bonding material extends between the cylindrical portions 39 and the cylindrical walls of the openings, and between the anges and the outer surface of the disc 14 immediately surrounding the openings, as indicated diagrammatically at 33. This construction is somewhat stronger than the construction previously described and may locate the terminal members with somewhat greater accuracy, because of the it between the cylindrical portions of the cut member 21a and the walls of the openings in the disc 14. Also in this form, the pressure required in the curing or vulcanizing ot' the bonding material is furnished by the close fit between the cylindrical portions 30 and the walls of the openings 22, and by the pressure exerted by the iiange 32. Thus the curing operation can be carried out merely by the application of heat. As before, the uid tight con nections are made by the bonding or cementing methods previously described.

ln Figure 7 l. have shown a cup-shaped closure member generally similar to the members 21a of Figures 5 and 6 but modified in two particulars, either one of which may be used without the other if desired. Here the member 2lb is shaped generally like the member 21a previously described and is secured in position in the same manner. However, the member is composed of a copper, steel, or brass inner portion 34 having an aluminum coating 34a. By the use of such aluminum clad materials in producing the cups, the portions of the cups exposed to the interior of the container and thus exposed to contact with the electrolyte are composed of aluminum which is satisfactory for electrolytic condensers, while the exterior portions of the cups are composed of a readily solderable metal such as copper, brass or steel.

,ln this form, the inner terminal member is preferably substantially identical with the terminal members previously described, and if desired, terminal members similar to the exterior terminals 23 may also be employed. However, the exterior terminal may be provided by the simple expedient of extending a portion of the exterior flange 32a to provide a terminal tab 23a. The tab 25u may be apertured as shown in the drawing so that if desired an electrical connection can be made to the tab without requiring any soldering. As noted above, either of the modications disclosed in this figure may be used Without the other. Thus for some purposes it may be satisfactory to provide an aluminum clad closure member and use it with a conventional terminal, or solder an external connection, for example, to the flange 32u. ln other instances, it may be satisfactory merely to use the terminal tab 23a, but to make the closure member out of a single metal such as aluminum. For other purposes it may be desirable to use the form shown in the Figure 7.

ln Figures 8 to ll, inclusive, l have shown a further modification of the invention wherein the insulating disc is or". thinner material and is reinforced by another metal disc. Here the electrode assembly iii is immersed in the electrolyte 11 as above. However, the container 12a has a cylindrical portion 35 at the open end thereof, extending beyond the inwardly projecting bead 36. The open end is closed by a disc 37 composed of suitable insulating material such as vulcanized fiber or one of the various materials heretofore mentioned, and having a peripheral ange as at 38. The disc 37 is reinforced by a metallic disc 39 having a flange dit, the discs 37 and 39 being apertured as at di. and 42, respectively, with the apertures aligned to admit the external terminal members 43. The external terminal members are welded to metallic discs 4d corresponding in function to the 4discs 21 heretofore described, and these discs are in tuin Welded to the internal terminal members 45. The assembly is completed by bonding the discs 44 to the underside of the insulating disc 37 as indicated at 46 in Figure l1. Then the reinforcing metallic disc, which is dimensioned to t closely within the insulating disc, is bonded thereto as indicated at 4] throughout substantially the entire contacting area of the two discs, and the flange 38 is bonded as indicated at 48 (Figure 8) to the portion 35 of the container. l preferably employ one of the bonding proc* esses mentioned above, and the operations of bonding the two discs together and of bonding the disc 37 to the conr are preferably carried out simultaneously.

ly this arrangement, it is possible to employ a less expensive insulating disc and yet secure ample strength by provision of the metallic reinforcing disc. Here the terminal members are supported and insulated from each other by the disc 37, and the arrangement is such that there is substantially no possibility of the external terminal members coming in contact with the external metallic reinforcing plate. As shown particularly in Figure li, the disc 44 is preferably of greater diameter than the opening 4Z in the metallic plate 39, and this opening is preferably of greater diameter than the opening 41 in the ber disc or insulating disc 37. By this arrangement, the tiber or other insulating material is interposed between two layers of metal in the region surrounding the openings 4l. Thus the liber is reinforced by the metal and has ample strength to withstand any strains imposed upon it, either by the terminal members or by internal pressures developed within the container.

ln the foregoing specification, i have described preferred forms of my invention in considerable detail. it will be understood that various changes and modifications may be made therein Without departing from the spirit and scope of the invention. Accordingly, it is to be understood that my patent is not limited to the preferred forms described herein or in any manner other than by the scope of the appended claims.

l claim:

l. A method of making a leak-proof joint for an electrolytic condenser container closure capable of maintaining the container sealed at temperatures of to 90 C. comprising coating the portions to be joined with a thermosetting material, partially drying said coatings, assembling said coated portions thereafter face to face, pressing and distorting at least one portion to partially embrace the other portion, and applying heat and pressure to said coatings to cure into a unitary leak-proof joint capable `of standing temperatures of 80 to 90 C. over long periods of time.

2. A method of sealing a terminal of an electrolytic device in an opening in an insulating disc through which the terminal extends comprising attaching the terminals to the inner and outer sides of the bottom of a cup-shaped metal element having an outwardly extending radial flange about the bottom portion, inserting the cup-shaped member in the opening of the insulating disc with a layer of a thermosetting plastic bonding material which can be cured under pressure and heat between contacting surfaces of the disc and cup-shaped member, pressing the free edge of the cup-shaped member outwardly and axially towards the bottom thereof to grip the portion of the disc surrounding the opening between the flange and deformed free edge, and pressing the plastic bonding material between the portions of the cup-shaped member and the disc, and thereafter curing the bonding material by applying heat to the assembly.

3. Method of joining a conductive metallic member and a dielectric member, comprising applying a layer of thermosetting bonding material between the portions of the two members to be joined, pressing and permanently deforming the metallic member to embrace with pressure the portion of the insulating member to be joined, and applying heat through the metallic member to react and cure the thermosetting bonding layer.

(References on following page) 2,776,467 7 4 References Cited in the lc of this patent 2,225,758

UNITED STATES PATENTS 1,924,893 Wackman Aug. 29, 1933 @347 2,084,973 `10h11 June 22, 1937 5 376354 2,122,477 Leonard July 5, 1938 8 Stein Dec. 24, 1940 Schnell Dec. 24, 194() Bohn June 3, 1941 Saunders Mar. 20, 1945 Saunders May 22, 1945 iwi ""M-

Claims (1)

1. A METHOD OF MAKING A LEAK-PROOF JOINT FOR AN ELECTROLYTIC CONDENSER CONTAINER CLOSURE CAPABLE OF MAINTAINING THE CONTAINER SEALED AT TEMPERATURES OF 80* TO 90*C. COMPRISING COATING THE PORTIONS TO BE JOINED WITH A THERMOSETTING MATERIAL, PARTIALLY DRYING SAID COATINGS, ASSEMBLING SAID COATED PORTIONS THEREAFTER FACE TO FACE, PRESSING AND DISTORTING AT LEAST ONE PORTION TO PARTIALLY EMBRACE THE OTHER PORTION, AND APPLYING HEAT AND PRESSURE TO SAID COATINGS TO CURE INTO A UNITARY LEAK-PROOF JOINT CAPABLE OF STANDING TEMPERATURES OF 80* TO 90*C. OVER LONG PERIODS OF TIME.

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