US2060832A - Dry cell - Google Patents

Description

Nbv.- 17, 1936. R. R. SMITH DRY CELL Filed y 27, 1930 /6 /0 Y am/ HHHIH v my i W A? l in f W, INVENTOR/ I BY Q 63 z3i ATTORNEYS.

Patented Nova l7, 19 36 umreo stares PATENT orrice DRY CELL Ralph E. Smith, Fremont, Ohio, assignor, by

mesne assignments, to Union Carbide and Carhon Corporation, a corporation of New York Application May 27, 1930, Serial No. 456,172

34. Claims. (01. 136-133) This invention relates to dry cells and particularly to improved means for closing and sealing such cells. The present application is a continuation in part of my application Serial No. 432,217

filed on February 28, 1930. g

In the manufacture of dry cells it has been common practice to close the cell by placing a layer of sand over the top of the mix body and then pouring a layer of sealing compound, such as coal tar pitch or a rosin-base sealing wax, over the sand. This type of closure is not altogether satisfactory due to the manufacturing difficulties experienced in handling the compound and in applying it to the cells. The completed closure is also quite brittle when cold and, consequently, is easily broken during handling and shipment; it becomes quite plastic when subjected to relatively high summer temperatures; and bulges or is forced from its proper location by internal gas m pressure.

Another objection to this type of closure is that it must be made comparatively thick in order to obtain the required strength, and this reduces cell space and electrode area which otherwise 5, might be employed to increase the capacity of the cell.

Another objection to this type of closure is that the area of the gas vent is capricious and not subject to manufacturing control. In dry cells having this type of closure the gas generated within the cell is vented through the joint between the sealing compound and the zinc container or electrode. The fact that this joint is not tight and that the cell gas is vented through as it is largely accidental and, as a consequence, the vent varies in size according to variations in conditions not readily controlled. As a result, the size of the vent is too large in some 'cells and too small in others, and in the majority of cases it so is effective for only a limited range of service conditions.

Therefore, some of the objects of this invention are to provide an improved closure or seal for dry cells which takes up very little of the 45 valuable space within the cell; is neat in appearance; low in cost; easy to manufacture and apply; uniform and efiective to vent gas from the cell; and avoids various objections encountered in the use of wax and other types of closures.

50 These and other objects and the novel features of this invention will be apparent from the following description and the accompanying drawing, in which:

Figs. 1- and 2 are enlarged vertical sectional 55 views of the top end of a dry cell showing the improved closure in place before and after the cell is sealed, and

Figs. 3 and 4 are, respectively, enlarged sectional and top views of a dry cell having a modified closure embodying this invention.

The improved closure may have a variety of forms according to the size and shape of the cell, its interior structure, and the use for which it is intended. As shown in Figs. 1 and 2. of the drawing, the improved closure comprises an annular 10 sealing member or cover ill that is relatively hard and resilient in comparison with the annular washer or seat it, formed for example from a relatively thin resilient metal, such as sheet steel from about .010 to .030 inch thick, having an upturned flange 5 l at its outer edge fitting snugly within the upper rim of the zinc container, can or cup l2, which rim is turned down over the flange. The cover preferably has a downturned flange it at its inner edge adapted to press 29 tightly against an annular insulating seat it that is relatively soft and yielding in comparison with the cover It, for example, a washer of paper, rubber, fiber, or similar material, mounted on the upper end of the central carbon electrode i5.

The downturned fiangemay have a sharp edge adapted to embed in the washer I l, as shown in Figure 2. A metal dowel l6, embedded in and extending upward from the center of the electrode l5, projects through an opening in the $0 washer M and serves as the central circuit terminal of the cell.

The-inner and outer surfaces of the cover it are preferably coated with a layer or body of enamel, varnish, lacquer, or similar material 5 which adheres to and insulates such surfaces and protects them from corrosion. The joint between the closure l0 and the container l2 may be further sealed with asphalt paint, rubber cement, or similar plastic composition; and the joint between the g top of the electrode l5 and the bottom of the insulating washer l4 may be sealed with a similar plastic composition. However, a sealing composition in either of these joints is not essential to the successful operation of the improved cell and closure.

When the coverlfl is secured in place it is pressed into effective sealing contact with the washer M in order to insure a fluid-tight joint between the cover, the washer, and the carbon 5 electrode. This pressure is preferably provided by deforming the cover I!) during the final assembling operation. Prior to this operation the downturned flange I3 is resting on the washer l4 and the upper edge of the upturned flange H is substantially flush with the top of the can l2 as shown in Fig. 1. The final assembling operation consists in rolling or crimping the upper edge of the can i2 inward and then down over the u p turned flange ll, thus rigidly and permanently securing the outer edge of the cover to the container. In performing this operation the outer edge of the cover is preferably depressed so that the cover is dished and exerts some downward pressure 'on the washer [4.

It is obvious that the jointformedbetween the flange i3 and the seat or washer M is of such a nature that, while gas-tight at ordinary pressures, it is adapted to open and allow the escape of any gas that accumulates to produce a pressure suflicient to overcome the resilience of the cover I0; While this method of venting alone serves well in some cases, it is usually desirable that it be supplemented by the provision of. another vent to operate at relatively lower pressure and of a more fixed nature.

The resulting .combination is particularly eflicient from the standpoint of cell quality, since any venting system must be a compromise between excessive loss of moisture from the cell and the accumulation of high gas pressures. In the present case the low pressure vent may be placed at a relatively lower capacity value than otherwise, since it must care only for normal operating conditions. This yields minimum loss of moisture from the cell, since the high pressure vent is normally closed and operates only under abnormal conditions such as, for example, may be introduced by excessive temperatures, or whenever abnormal quantities of gas are produced, causingexcessive pressures within the cell.

It is practical to control the character of the venting valve provided by the washer I4 and the flange I3; and the pressure necessary to open it, by the regulation of several factors. The primary, factor is the nature of the insulating. washer, and the second is control of the pressure that the flange l3 exerts upon the washer by varying the distance that the outer edge of the cover is depressed during the sealing and assembling operation, or by varying the thickness or resiliency of the cover material.

While the washer itself may in some cases form a practical low pressure vent by using suitable material, such as oil-treated pulpboard, that is impervious to moisture but pervious to gas under the mechanical pressure sustained, it usually is preferable to'use a carbon electrode that is sufficiently porous to vent the gas that normally occurs. A particular advantage of the latter procedure is that it facilitates the escape of gas generated in the lower regions of the. cell. In such a case the electrode may be partially impregnated with a watererepellent substance such as lubricating oil or paraflin to yield the desired venting characteristics. It is then preferable to use an impervious seat or washer such as rubber, fiber or more cheaply a washer made from a bibulous material such as pulpboard thoroughly impregnated with a water-repellent mixture composed of 50 per cent rosin and 50 per cent paraflin by weight. I

In six inch cells of the construction shown in Figures 1 and 2 suitable electrode impregnation covers a wide range according to the type of mix and paste used. At least one-tenth of the voids normally occurring in the carbon electrode are ordinarily filled with water-repellent impregnating material. More frequently the electrode impregnation is higher and may be such as to fill half the voids or even more. In this case an impregnated pulpboard washer as described above, and about .04 inch thick is suitable. Under these conditions the normal preferred practice to obtain suitable flange pressure upon the washer is to depress the outer edge of the cover about inch during the assembling and sealing operation.

It is obvious that the conditions for this control' will vary according to the materials selected, the purposes in view, and the type and size of cell, but it has been found that practical control can be readily achieved. This is true over a. practical range oftolerances with respect to relative positions of the top of the can and the top of the electrode. The ability of the construction to accommodate itself to variations of this nature represents a point of very important practical value from a manufacturing viewpoint.

On some types of dry cells, such as the sizes for flashlights, it is advantageous to use the modified form of closure shown in Figs. 3 and 4, which embodies the principles of this invention and differs only in a few details from the construction shown in Figs. 1 and 2. In Figs. 3 and 4, the annular sheet metal closure I!) has a downturned flange 18 at its outer edge and is bent downwardly within this flange, as at l9, so that a groove 20 is formed at the outer edge of the closure. The upper end of the zinc container I2 is crimped into the groove 20 and these parts may be slightly inclined outwardly and upwardly, as shown, the closure being thus permanently secured to the container bya substantially gas-tight joint. The washer I4 is carried by the carbon electrode l5, being supported thereon by an outturned annular flange 2| at the lower edge of a metal cap 22 which fits the upper end of the electrode. The cap projects outwardly..through the central opening in the washer and serves as the central circuit terminal ofthe cell. The top of the cap 22 is preferably provided with one or more openings, such as the slits 23, through which gas may escape after passing through the carbon electrode. A disk 24 of paperboard may snugly fit the outside of the electrode and the inside of the can in the space above the active material, sometimes designated as a cartridge, i. e., the mix body and the electrolyte, to prevent expanding electrolyte from contacting with the metal flange 2|. In all other features the cell and closure shown in'Figs. 3 and 4 may embody the same construction and operation as the one shown in Figs. 1 and 2.

It is also within the scope of this invention to vary the form of the central venting valve by omitting the flange I3, and by providing a. flange or ridge on the upper side of the insulating washer I4 to make contact with a flat surface at the inner edge of the closure l0. Also, the

outer edge of the closure I may be secured to I claim:

1. In a dry cell; the combination of means for venting the amount of gas normally generated therein without loss of a substantial amount of moisture; with means for venting abnormal amounts of gas to prevent the pressure thereof from injuring said cell.

2. In a dry cell; the combination of means for equalizing gas pressure in said cell and for venting the amount of gas normally generated therein without loss of a substantial amount of moisture; with means for. venting abnormal amounts of gas to prevent the pressure thereof from injuring said cell.

3. In adry cell wherein gas is generated at a varying rate during the operation of the cell, the combination of means whereby such gas is vented at a rate materially below the maximum rate of gas generation in the cell, to conserve the cell moisture and limit injurious effects for breathing; and means whereby additional gas is vented when the rate of generation exceeds the venting rate of the first mentioned means.

4. In a dry cell having a can; a carbon electrode in said can; a washer on said electrode having an opening; and a metal cover sealed to said can and having an opening therein with the edge thereof resting on said washer; the combination of means for venting a normal amount of cell gas through said electrode and the opening in said washer, with means for venting an abnormal amount of cell gas around said electrode through the opening in said cover.

5. A dry cell comprising a zinc container, a carbon electrode therein, a relatively soft and yielding insulating washer carried by said electrode, and a relatively hard and resilient'annular closure having its outer edge permanently secured to the upper end of said container and its inner edge contacting with said washer yet free to flex upwardly to vent gas from the cell.

6. A dry cell according to claim 5 in which the carbon electrode is sufliciently porous to vent gas from the cell and has a portion thereof exposed to the outer atmosphere.

'7. A dry cell comprising a container, an electrode therein, a washer of a relatively soft and yielding porous material carried by said electrode with a portion thereof exposed to the outer atmosphere, and a relatively hard and resilient annular impervious closure having its outer edge permanently secured to the upper end of said container and its inner edge contacting with said washer yet free to flex upwardly to vent gas from the cell.

8. A dry cell comprising a zinc container, a carbon rod electrode therein, a relatively soft and yielding insulating washer carried by said electrode, and an annular resilient sheet metal closure having its outer edge permanently secured to the upper end of said container and having its inner edge turned downwardly, said closure being so deformed that its inner edge presses tightly against said washer.

9. A dry cell comprising a container, an electrode therein and having a" portion thereof exposed to the outer atmosphere, said electrode being sufficiently porous to vent gas from the cell at a rate below the maximum rate of gas generation in the cell while preventing the escape of moisture, a seat on said electrode, and a resilient annular closure for said container, said closure having its outer edge permanently secured to the upper end of said container and its inner edge contacting with said seat yet free to flex upwardly to vent gas from the cell at a rate greater than the electrode.

10. A'dry cell comprising a container, a porous electrode therein normally adapted to vent gas from said cell and having a portion thereof exposed to the outer atmosphere, a relatively soft and yielding washer carried by said electrode, and a relatively hard and resilient annular closure for said container, said closure having its outer edge permanently secured to the upper end of said container by a substantially gas-tight joint and having its inner edge pressing against said washer but separable therefrom to release excessive gas pressure in said cell.

11. A dry cell comprising a zinc container; a porous carbon electrode therein having a portion thereof exposed to the outer atmosphere and normally adapted to vent gas from said cell; a relatively soft and yielding insulating disk carried by said electrode; and an annular resilient sheet metal cover having its outer edge permanently secured to the upper end of said container by a gas-tight joint and having its inner edge contacting with said disk but free to separate therefrom to release abnormal gas pressure in said cell.

12. A dry cell comprising a container, an electrode therein carrying a metal circuit terminal, a relatively soft and yielding disk mounted on said electrode and having an opening through which said terminal projects, and a relatively hard and resilient annular cover for said container, said cover having its outer edge permanently secured to the upper end of said container and its inner edge contacting with said disk yet free to flex upwardly to vent gas from the cell.

13. A dry cell comprising a metal container, a carbon electrode therein carrying a metal circuit terminal,-an insulating disk mounted on said electrode and having a relatively soft and yielding opening through which said terminal projects, and a relatively hard and resilient annular sheet metal cover for said container, said cover having its outer edge permanently secured to the upper end of said container and its inner edge contacting with said disk yet free to flex upwardly to vent gas from the cell.

14. A dry cell comprising a zinc container, a porous carbon rod electrode adapted to vent gas from said cell, a metal circuit terminal carried by said electrode, an insulating disk mounted on said electrode and having an opening through which said terminal projects, and an annular resilient sheet metal closure for said container, said closure having its outer edge permanently secured to the upper end of said container by a gas-tight joint and its inner edge turned downwardly, said closure being so deformed that said inner edge contacts with said seat but is displaceable therefrom to release abnormal gas pressure in the cell.

15. A dry cell comprising a container, an electrode therein, an annular closure member in contact with said electrode, and an annular closure member having its outer edge secured to the upper end of said container, one of said members being relatively hard and resilient and the other of said members being relatively soft and yielding, said relatively hard and resilient memher having a free edge in contact, with the upper surface of said relatively soft and yielding memher and being free to flex upwardly to vent gas from the cell.

.16. A dry cell as defined in claim 15 in which (iii i with said seat a the closure er a; in a carbon electrode e d or said electrode; etal eof attaches to it, a? langed down-we ti and sure in said cell tovent th- In a dry cell having carbon electrode therein; a A yielding preformer'i o said electrode; relatively container and the ther with a downtorned embedded Washer" 19. In a dry cell having a container with a carbon electrode therein; a seat upon the upper end of said electrode; and an annular resilient metal sealing member having the outer edge thereof rigidly secured to said container and the inner edge thereof flanged downward and termimating in a sharp edge embedded in said seat but adapted for being raised therefrom by gas pressure within said cell for venting the same.

20. In a dry cell having a container with a carbon electrode and an electrolyte therein; a metal dowel extending upward from said electrode; a seat comprising a washer of material impervious to said electrolyte encircling said dowel and forming a joint 'with said electrode through which said electrolyte will not pass; and an annular resilient sealing member having an upturned flange at the outer edge thereof over which the upper edge of said container is crimped, and a downturned flange at the inner edge thereof terminating in a sharp edge embedded in said seat but adapated for being raised therefrom by gas pressure within said cell for venting the same.

21. In a dry cell having a container with a flattopped carbon electrode therein; a preformed fiat annular disc of bibulous material impregnated with waterproofing material on the fiat top of said electrode; and a dished closure of resilient metal having the outer edge thereof rigidly secured to said container so that the inner edge thereof exerts a resilient pressure on said disc, said cover being, free to raise from said disc to vent excessive gases and to return to said disc to form 'a tight seal.

22. In a dry cell having a container;.a gaspervious waterproof carbon electrode in said container with a portion exposed to the outer atmosphere so that gas normally generated in said cell may escape therethrough; an impervious bibu- .lous washer 0n the upper end of said electrode;

and a sealing member oi resilient metal secured under stress between the upper surface of said washer and the upper edge of said container so that the pressure oi? '"iore gas than can escape through said electrode till raise the sealing mem her and permit escape of gas between the inner edge thereof and said washer.

23. A dry cell comprising a zinc container, a carbon electrode therein having a metal dowel projecting centrally from its upper end, a relatively soft and yielding dish mounted on said elec trode and having an opening through which said dowel protects, and a relatively hard and resilient annular cover for said container, said cover having its outer edge permanently secured to claim nsl of ihe ilating sis-ts metal,

said

the cell, and projecting pa is slitted to expose a portion of said electrode to the outer atmosphere.

2?. in a dry cell, a metal cup, a cartridge within said cup, an electrode arranged centrally or said cartridge, a resilient metal cover having a rigid gas-tight connection with said cup and having a central opening, a metal cap mounted on said electrode and projecting through said opening and having an annular shoulder, and an annular insulator resting on said shoulder and underlying said cover, the inner edge of said cover being turned at an angleto the remainder and pressed into sealing relation with said insulator by tension exerted solely by said cover.

28. A dry cell comprising a container electrode; an electrode member within and spaced from said container electrode; active material in the space between such electrodes; a closure for the cell comprising a metal cover member supported by said electrode member and havirm a marginal portion secured to said container electrode; said container electrode and said cover member consisting of dissimilar metals; and a coating of insulating material upon the interior surface of said cover member. g

29. A dry cell comprising a container electrode; an electrode member within and spaced from said container electrode; active material in the space between said' electrodes; a closure for the cell comprising an annular metal cover member hflV'? ing one margin thereof secured to said container electrode and having another margin thereof sup-: ported by said electrode member; said container electrode and said cover member consisting of dissimilar metals; and a layer of insulating material adhering to and coating the interior surface of said cover member.

30. A dry cell comprising a metal container electrode; an electrode member within spaced from said container electrode; active material between said electrodes leaving a free space above said active material; a metal terminal can carried by said electrode member, said having a portion thereof within said freespace; an annular metal cover having its inner ma? jacent to but insulated from said cap and "having its outer margin permanently secured to said con tainer electrode; and a coating of-insulating material upon the interior surface of said cover.

Bl. A dry cell comprising a container electrode; an electrode member within and spaced from said container electrode; active material in the space between said electrodes; a closure for the cell com prising a metal cover member supported by said electrode member and having a marginal portion secured to said container electrode; said container electrode and said cover member consisting of dissimilar metals; and plastic material sealing the joint between said cover member and said container electrode.

32. A dry cell comprising a container electrode; an electrode member within and spaced'from said container electrode; active material in the space between said electrodes; a closure for the cell comprising a metal cover member having a portion supported by said electrode member and having a marginal portion secured to said'container electrode; said container electrode and said cover member consisting of dissimilar metals; a surface coating of insulating and protective material upon the interior surface of said cover member; and plastic. material sealing the joint betweensaid cover member and said container electrode.

33. A dry cell comprising a container; an electrode therein; a washer of a relatively soft and yielding porous material carried by said electrode with a portion thereof exposed to the outer atmosphere, the said washer being impervious to moisture but pervious to gas under the pressures developed in the cell; and a relatively hard and resilient annular impervious closure having its outer edge rigidly secured to the upper end of said container and its inner edge contacting the said washer yetfree to flex upwardly to vent gas from the cell.

34. A dry cell comprising a metal container; a carbon electrode therein; a metal cap mounted on the upper end of said 'electrode and having an out-turned flange; a relatively soft and yielding washer mounted on said flange and having an opening through which said cap projects, the said washer being impervious to moisture but pervious to gas under pressures developed within the cell; and a relatively hard and resilient annular cover for said container, said cover having its outer edge permanently secured to the upper end of said container and its free inner edge contacting with said washer yet free to flex upwardly to vent gas from the cell.

RALPH B. SMITH.

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