US3061660A

US3061660A - Reinforced cell closure

Info

Publication number: US3061660A
Application number: US47407A
Authority: US
Inventors: Jr Raymond L Schenk
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1960-08-04
Filing date: 1960-08-04
Publication date: 1962-10-30
Anticipated expiration: 1979-10-30

Description

Oct. 30, 1962 R. L- cHENK, JR 3,061,660

REINFORCED CELL CLOSURE Filed Aug. 4, 1960 i, & m

N INVENTOR. m mozva 4. JCHDV/f, 1,,

fM (MW/ A rrow/5r ilnited S tates York Filed Aug. 4, 1960, Ser. No. 47,407 4 Claims. (Cl. 136-133) This invention relates to a cell closure for a cylindrical galvanic cell, and more particularly, it relates to a reinforcement ring for use with such a cell closure.

United States patent application, Serial No. 774,931, filed November 19, 1958 in the names of R. Carmichael et al. discloses an excellent closure for cylindrical alkaline galvanic cells which is extremely resistant to caustic creepage. The disclosed cell closure comprises an annular gasket of a hard, di-electric, plastic-like material which is resistant to cold-flow and a metallic container cover, the gasket being interposed between the cell container wall and the edge of the cell cover in supportingrelation with the cell cover. The actual sealing is effected by radially compressing the gasket between the container and the cell cover under a high radial force. After the compressive force is removed from the container, the gasket will exert a radial compressive force outwardly against the container which is substantially equivalent to, but not greater than, the yield strength of the metal of which the container is made.

in the preferred method disclosed to accomplish such radial sealing, that is, by forcing the container with the gasket and cover in place through a reducing or sizing die, a shoulder must be provided at the open end of the container to support the seal gasket during sealing.

Unfortunately, the use of a container with a shoulder at the top presents a number of difficulties during the manufacturing process. Namely, it prevents the cells from being rolled uniformly from station to station during manufacture and such a container is diflicult to produce. Extreme control of the container forming equipment is necessary to provide a sharply defined step and yet not form it so deeply that the container wall is weakened.

Accordingly, the principal object of the invention is to provide a radially sealed galvanic cell wherein a straight sided container may be employed.

The principal object of the invention is accomplished by a galvanic cell wherein the cell closure comprises an annular gasket of a hard di-electric material which is resistant to cold flow interposed and radially sealed between the container wall and a two member cell cover, one member of which is a washer type lid which imparts resiliency to the back up support for the gasket when it is radially sealed; the top of the outside of the container being provided with a reinforcement ring.

The term cold-flow as used herein and in the appended claims, refers to the gradual deformation of a material that occurs when that material is subjected to a constant load at room temperature. Materials which deform very little or only when large forces are applied and which do not continue to deform or creep when the force is applied for a considerable length of time are said to have good cold flow characteristics.

Additionally, the seal gasket used must be made from a material which will not be attacked by the corrosive electrolyte of the cell and which has good di-electric properties as well, the gasket serving to insulate the positively and negatively charged parts of the cell. Of course, the material must be one generally characterized by its high compressive and shear strength and one capable of withstanding large stresses without a tendency to cold flow.

atent ice Nylon, a polymer of hexamethylene diammonium adipate, is a hard plastic composition that has been found to be a suitable material for use in practice of the invention. A nylon plastic sold under the trademark Zytel is the preferred material.

The invention will be more readily understood by reference to the accompanying drawing wherein:

FIG. 1 is a front elevation view, partially in section, of the top portion of a cylindrical galvanic cell which shows the seal assembly of the invention prior to being radially compressed; and

FIG. 2 is a view'of the cell of FIG. 1 after it has been radially sealed.

Referring now to the drawing, and particularly FIG. 1, the cell closure of the invention comprises an annular generally L shaped hard nylon gasket 10 which is provided with a flange 12 to support the gasket 10 on the top of the cylindrical metal cell container 14 and which is interposed between said container 14 and a two member cell cover. One member of the cell cover is an annular generally U shaped ring 16, preferably made of nickel or nickel plated steel, and which has an integral protruding cap 18 which receives the central electrode 19 of the cell and thereby serves as one terminal of the cell. The other member of the cover is a metal washer 20, preferably made of steel or stainless steel, which resides in the U shaped portion of the first cover member 16. The steel washer 20 gives back-up support when the cell is radially sealed, and provides resiliency to keep the seal tight. A metal reinforcing ring 22 provided with an inward facing flange 24 and a dependent flange 26, is provided over the top of the container Wall 14 and adjacent the gasket flange 12 which supports the gasket 10 on the container wall 14.

The actual radial sealing of the cell, as shown in FIG. 2, may be accomplished in a number of ways, a typical way being by pushing or forcing the container 14, with the gasket 10, cover members 16 and 20 and reinforcement ring 22 in place, through a sizing die so that the ring 22 is reduced in diameter to the diameter of the unreinforced portion of the container 14, thereby exerting a maximum radial seal compressive force on the container 14. The deformation of the metal container 14 by the sizing operation is permanent for any spring back of the container 14 after passing through the sizing die is prevented by the reinforcement ring 22.

In order to test the effectiveness of the cell closure of the invention, 29 D size alkaline cells were made with the cell closure. The cells were overcharged, subjected to thermal shock, high humidity and then placed on shelf for a period of two years. Less than 10% of the cells showed any evidence of leakage and this was a minor degree. This test conclusively demonstrates the ability of the closure of the invention to withstand caustic creepage under abusive conditions.

I claim:

l. A closure for sealing a galvanic cell against electrolyte leakage; said galvanic cell comprising a cylindrical cupped metallic container of uniform diameter and an electrolyte therein; said closure comprising an annular hard plastic gasket which is resistant to cold flow having a flange extending over the top of said container and which is interposed between said container and a two member cell cover; the first member of said cover being an annular generally U shaped metal ring having an integral centrally located protruding terminal cap and the second member of said cover being a metal washer which resiliently resides in the U shaped portion of said first cover member, and an external metal reinforcement ring encircling said container at its top which has a depending flange which presents a flush surface with said container wall and an inwardly facing flange adjacent said flange on said gasket; said gasket being in a state of radial compression between said container and said cover and exerting a radial force substantially equivalent to, but not greater than, the yield strength of the metal of which said container is made.

'2. The closure of claim 1 wherein said gasket is gen- 'erally L shaped and made of hard nylon, said generally .U shaped ring is made of a material chosen from the group consisting of nickel and nickel plated steel and said metal washer is made from a'material chosen from the group consisting of steel and stainless steel.

3 A sealed galvanic cell comprising a cylindrical cupped metallic container of uniform diameter, said cell being sealed at the open end of said cupped container by a closurewhich comprises an annular hard plastic gasket which is resistant to cold flow, having a flange extending over the top of said cupped container and which is interposed between said container and a two member cell cover; the first member of said cover being an annular generally U shaped metal ring having an integral centrally located protruding terminal cap and the second member of said cover being a metal washer which resiliently resides in the U shaped portion of said first cover member, and an exterior metal reinforcement ring encircling said container at the top which has a depending flange which presents a flush surface with said container wall and an inwardly facing flange adjacent said flange on said gasket; said gasket being in a state of radial compression between said container and said cover and exerting a radial force substantially equivalent to, but not greater than, the yield strength of the metal of which said container is made.

4. The sealed galvanic cell of claim 3 wherein said gasket is generally L shaped and made of hard nylon, said generally LI shaped ring is made of a material chosen from the group consisting of nickel and nickel plated steel and said metal washer is made of a material chosen from the group consisting of steel and stainless steel.

7 References Citedin the tile of this patent UNITED STATES PATENTS 2,495,247 Friedman Jan. 24, 1950 2,541,931 McEachron Feb. 13, 1951 2,636,062 Colton Apr. 21, 1953