US2850558A - Leak-resistant dry cell - Google Patents

Description

swt 2, 1958 L. F. URRY LEM-RESISTANT DRY CELL Filed Sept. l, 1955 ATTORNEY rainer.

LEAK-RESSTANT DRY SELL Lewis l?, Urry, lakewooti, (Ehio, assigner to Union Carbide Canada Limited, a corporation of Canada Application September l, 1955, Serial No. 531,922

9 Claims. (Cl. 13G-133) and although millions of dollars have been spent in 4research in attempts to solve it, there is still need for improvement. One of the principal attacks on the problern has been made from the standpoint of attempting to prevent leal-:age by placing the cell in a closed concontainer, but this suers from the disadvantage that the metal is subject to corrosion by cell exudate and may be destroyed by it, thereby defeating its purpose. On the other hand, non-corrodible containers do not have the mechanical strength of metal containers and suffer from lthe disadvantage that pressure built up within the container is suiicient in many cases to cause the container to yield by bulging, and under extreme conditions, even to burst.

To avoid the disadvantages of the high pressure system l just described, suggestions have been advanced for lowpressure systems in which the attempt is made to restrain liquid leakage while permitting continuous venting of gas from the cell. This venting may take place through l the central carbon electrode and out a perforation in the terminal cap placed thereon or may be expected to `occur through adventitous voids such as those between closure and jacket for instance. .T he principal diihculty -encmlntered in such systems is that the gas-venting paths tend to become obstructed, sometimes during manufacture, sometimes during use of the cell so that` the intended low-pressure system actually becomes a highpressure one, and bulging or rupture of the container and leakage of liquid ensue.

Gne widely used expedient comprises a metal it is the principal object .of this invention to provide W in a leak-resistant cell a continuously operable gasventing path. Y

More specifically, it is an object of the invention to provide a continuously operable venting path suitable 4particularly for use in a type of construction utilizing a noncorrodible container.

These objects are attained by the invention which will vbe described with reference to the accompanying drawing in which:

Fig. l is a vertical elevation partially in section of a dry cell embodying the invention;

Fig. 2 is a similar view of the top portion only of another type of cell construction embodying the invention;

Fig. 3 is similar to Fig. 2 showing another embodiment of the invention;

Fig. 4 is similar showing another embodiment;

Fig. 5 is similar showing yet another embodiment; and

Fig. 6 is a vertical section of the top portion of a cell embodying the invention after use.

Broadly, the invention comprises in combination, a venting washer below the top closure of a leak-resistant dry cell and a yieldable inner sealing member defining a free space above the depolarizer mix of the cell.

Referring to the drawing, there is shown in Fig. l a leak-resistant cell of a particular type of construction for which the invention is well suited. The cell C comprises a zinc cup electrode l0 having therein immobilized electrolyte l2, a depolarizer mix 14 and a carbon electrode lo embeddedin the depolarizer mix 14. Just below the top of the cup l0 and so placed as to dene a lower free space le above the depolarizer mix 14 and an upper free space Z4 is an inner seal comprising a top collar 2l) and a soft seal 22 held in position by the upper end of the cup l@ which is inwardly bent as shown at 23. The top collar ZG is preferably composed of paper or other iibrous material protected against penetration of electrolyte by a coating 2l of plastic such as polyethylene, for example. A bead 25 may be provided in the cup electrode lil to aid in locating the top collar during manufacture of the cell. The sealing layer 22 is preferably composed of a soft wax, a microerystalline wax having a melting point of about 160 C. having been used successfully. A mixture of asphalt and petrolatum may be used for this layer if desired. Spaced somewhat above the soft seal ZZ and in the upper free space 24 is a venting washer 2e having a central aperture through which the carbon electrode lo passes. Preferably the washer 26 fits the electrode 16 rather snugly so as to aid in positioning it during manufacture. The venting washer must provide, in conjunction with the closure of the cell,.a passage for gas and preferably is composed of paper or other fibrous material.

A preferred closure comprises a flanged metal cap 2S supported on the top of the carbon electrode 16 and carrying an insulating washer Sil on which rest the inner peripheral edges of a metal washer 32 whose outer edges are in liquid-tight engagement with a jacket 34. in the construction shown in Fig. l the jacket 34 is noncorrodible, bars the passage of liquid and fits the electrode i9 rather loosely, thereby providing a supple` mentary chamber 36 for receiving cell exudate in the event of perforation of the zinc electrode 10. Also as shown, the jacket 34 is secured to a false bottom 33 which makes contact with the zinc electrode 10.

As shown in Figs. 2 to 5 inclusive, the invention is applicable to other constructions. For example, referring to Fig. 2 the venting washer di) may be of a diameter somewhat greater than that of the zinc cup electrode lll and rest upon its top edges. Or, as shown in Fig. 3, a one-piece cover 42 which may be provided with a vent ed may be used instead of the three-piece closure shown in Figs. l and 2. It will be observed that the venting washer 40 used in this Vconstruction is of the larger diameter as shown in Fig. 2. This servess to insulate the cover 42 from the cup electrode llt) as well as to serve its venting function. In Fig. 4 an alternative construction is shown in which the outer peripheral edges of the metal washer 46 of a three-piece closure are attached to the upper edges of the zinc cup 10, the internal construction otherwise being the same as that shown in Fig. 1. With this type of construction any jacket (not shown) may be provided for the cell and secured thereto in conventional manner. As shown in Fig. 5 a tube 50 of cardboard or other gas-permeable material may be provided about the carbon electrode 16 in the free space 1S to prevent cell exudate from coming into contact with the electrode and thereby blocking it Y 3 to the passage of gas. Of course such a Ytube can be used .in any of the Vconstructions shown.

Having described the construction of cells incorporating theV invention, itsoperation may now be visualized. During use of 'a dry cell, and `especially under severe conditions, gas is released.` This gas may be-vented through r around the carbon electrode 16, into the upperfree 4space 24 and eventually out through Vthe closure `orjacket side wall without eect on the inner seal.

Y yAt the sarne time,'1iquid may be exuded from the dep'olarizerV mix and accumulated in the free space 18.v

Under thepressure Aof such liquid and entrapped'gas, the inner `seal made up of the top collar and sealing layer 22,'being yieldable, is displaced upwardly in theV directionlof the top closure. ByY such displacement, the

member 32 and 'the jacket 34. In the cases of Figs.'2

and 3, VAthis function is performed by 'the venting washer It will be seen, however, that'despite the displacemen joftheinner seal, a venting path for ,gas still remains.V

ThisY path leads'from theY free vspace 18, up through the electrode 16,- or between it and the displaced edges of `the inner seal, to the venting washer 26 and to the insulating washer 30 andV eventually out of the cell and its container. Thus, gas is continuously ventedand no substantial gas pressure is ever built up in theV cell Yor, its

container. VIn a cell vconstruction Vhaving ja Vone-piece metal cover, as 'shown in Fig. 3, the venting path may be throughfthe vent VMor Vthrough thejoint between the .cover-42 and thejacket ,34' or'Y through the side wall Vof the jacket 34. It will be noted that Vthe venting Washer 4G overlies Vthe top edges ofV the container electrode10 and extendsl substantiallyto the inner walls of the jacket 34. Y .Y Y

. A` number of 4test cells embodying the invention have been Ymade :and Vsubjected to tests ranging from normalk usageV .toseve reV abuse. These tests demonstrated the eiectivenessof the invention, for cells otherwise identical inrconstruction but Vh avin'gno ventingwasher failed by: bursting under ,the-pressures developed .therein while those. cells Vembodying theinvention consistently showed Vno evidence of pressure'build-up-and did not leak-under breakdown tests. Y One of the vadvantages of the tvinvention'derives from the elimination of theV conventional ventin the cap lon the central electrode. In prior constructions-.suchvents have been used to'permitfgas to escape, but some liquid frequently'escaped'.therefrom as well, damaging the contacting surface. 4In the construction of the invention the cap isjpreferably'not vented,rand-a moretortuous venting path is.n provided. Such moisture -as 1may be 4entrained with the Vgas is entrapped under theV closure or' absorbed in -theventing or insulating washer. j

Although specitiostruetural,details vhave been--given Vherein by way ofY illustration, Vit will be -apparentthatethe in the cell; and in said free space between said inner seal Y and said closure a substantiallyrflat venting washer adaptabove said depolarizer mix Yanda free spaee'below said ed to provide a path for venting gas from said cell in association with said gas venting means Vin said Vclosure Yregardless of the position of said'displaceable inner seal.

2. The combination defined byclaim 1 in which said inner seal comprises a non-absorbent collar extending fromsaid cup electrode to said secondjelectrode'and a soft, tacky sealing material overlying said collar and adapted to adhere to said cup electrode and to exposed portions of the underside of said closure when said seal is V displaced.

3. The combination defined by'claim ly in which said closure comprises a anged -metal terminal member carried by the central electrode of said cell, an insulating washer carried on the ange of said member and a metal washer, the innerperipheraledges of which rest upon said insulating washer, said insulating `washer constituting said gas venting means. i

l4. rhevcombination defined by claim 1 in which there,

closure, saidrinner sealbeing displaceable Vin the direction'of said top closure in response to pressure within lthe cell; and a substantially flat venting lwasher in said free Y space between said inner sealy and "Said closure, said venting washer-providingfa venting pathfforygas in associationwith said top closure ventingmeans'regar'dless of'the position of-said inner seal. Y

`6. A Yleak-resistantl dry cell comprising a; consumable metall cup anode having therein electrolyte; depolarizer mix and acentral non-consumable electrode, a rigid top` closure for said cell secured to saidY cup anode and hav- Ving gas ventingmeans therein;V an inner `seal positioned 'in said cupy anode between saiddepolarizer-mix *and* said closure and out of contact-with either, 'thus deninga -free space above said-depolarizer-mixanda free Vspace below said closure, -said inner seal beingdisplaceable in the direction olf-'said top closure in response to pressure" within said-cell; and a substantially atventingwasher'in said free space between'said inner seal-and'said closure, said venting washer providing a ventingpath `for gas in as-` sociation with said'top Yclosure ventingmeans regardless of the -position of said inner seal. Y

7. A leak-resistant dry cell comprising'a consumable `metalcup Vanode having therein electrolyte, depolarizer mix and a central non-consumable electrode,an electro-Y lyte-proof jacket for Said cup anode longer thansaid anode andY extending Vbeyond it, a rigid top closurefor said cell secured to said 'jacket and having gas venting means therein, an inner seal in said cup anode positioned Vprinciples of the invention may be appliedto other con- `structions-than those shown.`

Iclaim: fr Y g; Y1,. In asleak-'resistant cell comprising -a cupelec- Y f trode `containing electrolyte'nvetV depolarizer jmix, and a s second. electrode embedded therein, the combination of a rigid' closure for Vsaid cell; `-said' closure having, gas-,ventfing meanstherein; an yinnersealrpositioned between 'said depolarizer mix and said closure'fand out of; contact depolarizer mix, Vsaidinnerseal being displaeeable in the direction offsaid closure in Yresponse to pressure with` Ybetween said depolarizer mix and said closure Yand out of contact with either, thereby lde ining a free spacegabove saiddepolarizergmix and a're'e space below said closure, said inner seal being displaeeable in the direction ofgsaid top Vclosure in response to pressure within said'cell; kand asubstantiallylat ventingwasher in Ysaid free spacebetween said innersealjand said top closure, said venting `washer providing aventing pathfor gas in association with said Vtop closure venting meansy regardless oflthe posif tion of s aid inner seal.

I l 8. Ina Vleak-reslstant dry cell Vcomprising a consumable metal cup anode containing therein, a depolarizer mix 1 and Ya central electrode embedded thereimthe combina- Y tion of a jacket and a rigid top closure for said cell, said closure being secured to said jacket and having gas venting means therein; a displaceable inner seal positioned between said top closure and said depolarizer mix and out of contact with either, thus @dem'ng a free space above said depolarizer mix and a free space below said top closure, said inner seal being displaceable in the direction of said top closure 'in response to pressure within said cell; and in said free space between said cell and said top closure a substantially at venting Washer adapted to provide a path for venting gas from said cell in association with said gas venting means in said closure regardless of the position of said displaceable inner seal, said washer being of a diameter greater than the diameter of said cup anode,

e 9. The combination defined by claim 8 in which said closure is of metal in one piece.

References Cited in the le of this patent UNITED STATES PATENTS 1,866,016 Deibel July 5, 1932 2,060,796 Cahoon Nov. 17, 1936 2,060,818 Marsal Nov. 17, 1936 2,060,832 Smith Nov. 17, 1936 2,505,014 Terlizzi et al Apr. 25, 1950 2,707,200 Urry et al Apr. 26, 1955 2,773,926 Glover Dec. 11, 1956 2,790,022

Glesner Apr. 23, 1957

Claims (1)

1. IN A LEAK-RESISTANT DRY CELL COMPRISING A CUP ELECTRODE CONTAINING ELECTROLYTE-WET DEPOLARIZER MIX, AND A SECOND ELECTRODE EMBEDDED THEREIN, THE COMBINATION OF A RIGID CLOSURE FOR SAID CELL, SAID CLOSURE HAVING GAS VENTING MEANS THEREIN, AN INNER SEAL POSITIONED BETWEEN SAID DEPOLARIZER MIX AND SAID CLOSURE AND OUT OF CONTACT WITH EITHER, THUS DEFINING A FREE SPACE BETWEEN SAID SEAL AND SAID CLOSURE AND A FREE SPACE BETWEEN SAID SEAL AND SAID

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