US3524770A

US3524770A - Dry cell seal

Info

Publication number: US3524770A
Application number: US564182A
Authority: US
Inventors: Milton E Wilke
Original assignee: Servel Inc
Current assignee: Servel Inc
Priority date: 1966-07-11
Filing date: 1966-07-11
Publication date: 1970-08-18
Anticipated expiration: 1987-08-18

Description

M. E. WILKE DRY CELL SEAL Filed July 11, 1966 A I I I I/VJl/VIV/ INVENTOR: Ml lfon United States Patent Oflice 3,524,770 Patented Aug. 18, 1970 3,524,770 DRY CELL SEAL Milton E. Wilke, Freeport, Ill., assignor to Servel, Inc., Freeport, 11]., a corporation of Delaware Filed July 11, 1966, Ser. No. 564,182 Int. Cl. H01m 1/02 US. Cl. 136-133 3 Claims ABSTRACT OF THE DISCLOSURE The top of the can of a dry cell is bevelled to support thereon a non-conductive washer having a diameter less than the inside diameter of the non-conductive sleeve which covers and extends beyond the top of the can and greater than the diameter of the bevelled top of the can, a body of sealing composition covering the top surface of the washer and sealingly engaging the external surface of the can at the bevel and the portion of the sleeve which extends beyond the can.

This invention provides an improved sealing arrange ment for electric dry cells of the common cylindrical type.

In closing the tops of the cylindrical cans of zinc or other metal forming the negative electrodes of dry cells and sealing the tops of the assembled cells, the practice for many years has been to pour a sealing composition of wax, pitch, asphalt, etc., into the tops of the cans to prevent the passage of moisture or gases into or out from the interiors of the cells. Except for provision for very limited escape of gases through the porous body of the carbon positive terminal, each individual cell of the common acid electrolyte type is hermetically sealed. In the conventional arrangement, a cardboard washer is arranged inside of the can a short distance below the open top edge to support the sealing material. A shoulder may be provided in the can to support the washer, but more commonly the washer engages the inside of the can and the carbon rod terminal with snug friction fits to support itself in position and to support the sealing material which is poured upon it to close and seal the cell. The sealing material may extend only to the level of the top of the can or may extend somewhat above the top of the can to seal to the cylindrical paper jacket that is usually provided as a sleeve over the can. The direct seal to the paper jacket is desirable, especially if a metal top cover is provided; otherwise, leakage of corrosive battery fluid through a perforation in the can may creep along the paper jacket and escape from the cell either past the periphery of the metal top or through an opening resulting from corrosion of the metal top by the battery fluid.

The principal object of the invention is to provide an improved, more dependable seal for dry cells. Subsidiary objects and advantages include the saving of significant quantities of zinc or other anode metal, some saving in sealing composition, and certain advantages in the cell manufacturing processes, including, particularly, the control of the level of the seal supporting washer and the reduction of air bubbles in the sealing material. These and other advantages of the invention will become apparent to those skilled in the art as the following detailed description proceeds in conjunction with the drawing which is a cross-sectional view of a dry cell embodying the invention.

The cell interior, which is conventional, is not illustrated. A cylindrical can 1 of zinc or other anode metal is surrounded by a sleeve 2 of laminated paper, usually with a moisture barrier between the laminations, and the paper sleeve is surrounded, in turn, by a steel outer jacket 3. A metallic plate 4 extends across the bottom of the can and a top plate 5 covers the top of the cell, receiving the top end of positive terminal rod 6 in a central depression 5a. In known manner, the cell is held tightly together between the top and bottom plates by the ends of steel jacket 3 which is crimped at both ends over the peripheries of the top and bottom plates, the paper jacket 2 serving to electrically insulate the jacket from the plates which serve as the terminals of the cell.

In accordance with the invention, the top marginal portion of can 1 is beveled inwardly to provide a positive support 1a for cardboard washer 7. The can is considerably shorter than would be the cans for conventional seals, resulting in a substantial saving of material. Washer 7 is centered by terminal rod 6 which, in turn, is supported at its axial position by the depolarizing mix of the cell which is not shown because it is conventional. The sealing layer 8 is poured in molten condition into the top of the cell after insertion of washer 7 and before the assembly is completed by placement of top plate 5 in position and crimping of jacket 3. It will be noted that the sealing composition sealingly engages the external surface 1b of the beveled portion 1a of can 1 and a substantial portion of the length of laminated paper sleeve 2. This construction renders it virtually impossible for battery fluid to escape from the cell at its top.

It will be noted that substantially all of the interior surface lb of the anode can is exposed to the interior of the cell for electro-chemical action; that is, no part is wasted by filling with sealing material as in conventional practice heretofore. Nevertheless, the sealing material sealingly engages not only the can, but also a substantial portion of the laminated paper sleevethe portion between the bevel shoulder and the top plate of the cell. This provides a security not heretofore attained, and this desirable objective is attained, not by the use of additional materials or complicated structures, but by the improved construction which uses less anode metal and less sealing composition.

It will also be noted that the level of washer 7 is positively established since it is seated upon the top of the can. With this inherently reproducible condition, it is an easy matter to provide the desired sealing body arrangement in all cells by simply applying a metered amount of molten sealing composition to the top of each cell.

Invention is claimed as follows:

1. In a dry cell having a cylindrical electrode can, a non-conductive sleeve surrounding the can and extending beyond the top thereof and an axial terminal rod, the improvement comprising an inturned bevel in the top of the circumferential side wall of the cylindrical electrode can throughout the circumference thereof, a non-conductive washer seated upon the top of the can and having a diameter less than the inside diameter of the sleeve and greater than the diameter of the beveled top of the can,

. 3 and a body of sealing composition covering the top surface of said washer and sealingly engaging the external surface of the can at said inturned bevel and a portion of the sleeve which extends beyond the can.

2. A dry cell improved in accordance with claim 1 and including a metallic top plate arranged within the sleeve and covering the terminal rod and sealing body.

3. A dry cell in accordance with claim 2 and including a metallic jacket surrounding the sleeve, said jacket being crimped over the periphery of the top plate with the non-conductive sleeve therebetween to hold the top plate securely in position.

4 References Cited UNITED STATES PATENTS 6/1955 Seavey et al. 136-433 8/1957 Anthony et a1 136l33 1/1969 Knight 136133 X 4/ 1940 Anthony 136133 4/1957 Glesner 136-133 X FOREIGN PATENTS 6/ 1955 Italy.

WINSTON A. DOUGLAS, Primary Examiner O. F. CRUTCHFIELD, Assistant Examiner