Title of Invention

A DRY CELL SEAL CLOSURE

Abstract

A dry cell seal closure comprising ring washer with U shaped cross section and a positive terminal circular metal cap, the said closure being fitted airtight at the top of zinc can by crimping and ribbing its upper extended edge and wherein the said washer made of polyethylene having central circular aperture adapted to guide carbon rod and the upper periphery of the washer being projected outwardly and having inward ridge, wherein said peripheral projection adapted to fit tight on the zinc can, also adapted to support the rim of the can while crimping and further the said washer having inward ridge at its upper edge to form a groove inside U shaped cross section adapted to receive flange of metal cap in the groove, also the ridge guide downward crimping edges of the zinc can and wherein the said positive terminal circular metal cap being made of brass having metal coating on it with shape adapted to fit on the carbon rod and its lower flange being snap fitted in the groove provided in the washer.

Full Text

FORM - 2A THE PATENT ACT, 1970 COMPLETE SPECIFICATION SECTION 10 " DRY CELL SEAL CLOSURE MATSUSHITA LAKHANPAL BATTERY INDIA LIMITED. As Indian company incorporated in mdia underthe Companies Act, 1956 of India having its registered office at Makarpura, G.I.D.C, Vadodara390 010 State of Gujarat, India. The following specification partictilarly describes the nature of this invention and the manner in which it is to be performed: - The invention relates to sealing of Leclanche type (typically zinc- carbon) dry cell and a method of assembling it. More particularly, this invention relates to the construction incorporating a seal closure for the open end of a cylindrical container of the zinc- carbon dry cell (referred to merely as "a dry cell" hereafter) on which the closure has peripherally disposed thereby providing a seal for the container. BACKGROUND In developing countries such as India, consumption of dry cell for example, especially AA type is quite high due to miniaturization of portable equipment. The International Electrotechnical Commission (IEC) has classified the AA type dry cells into three categories namely R-6 C (Capacity), R-6P (Power) and R-6S (Standard). Generally R-6C and R-6P type dry cells are used for high or moderate current drain requirement of the equipment whereas R-6S (Standard) is used for moderate to low current drain appliances. Conventionally, R-6S dry cells generally comprises of a cylindrical zinc container, acting as anode with a depolarizer mix extruded/ filled into the container separated by coated paper separator and having a carbon, rod in the center which functions as the current collector for the depolarizer mix. The carbon rod is centered by guiding it through a washer (generally made of wax coated duplex board), just placed over the depolarizer mix, latter also serves as a insulating media for tamping the depolarizer mix for the reaction across the zinc anode and paper lined interface. The cells are generally sealed by inserting supporting washer (generally made of wax coated duplex board) over the cathode mix and then dispensing molten asphalt onto the washer thereby providing an asphalt seal for the cells while also providing an air space above the depolarizer mix and below the asphalt seal to accommodate the discharge gases and exudate of the cell. A metallic terminal cap generally embedded into plastic (generally employs a mixture of high density polyethylene and low density polyethylene, ratio is based on the moldable capacity) making it as one piece moulded cap (referred to as "mould cap" hereafter) components or parts is placed over the carbon rod whereas the rest of moulded plastic material resting on the asphalt sealing which is peripherally crimped at the upper edge of the open end of the cylindrical zinc can and further is ribbed for better sealing. Finally, the entire assembly is encased by an insulating PVC sleeve that cover the sides of the zinc can/or a metal or polymer coated paper jacket that surrounds the cell, with only the positive and negative terminals as bare zinc or with a tenninal plate exposed. The disadvantage of the above-considered mould cap is that it often leads to hair line cracks while manufacturing these moulded component parts or during assembling while nianufacturing the cells due to various reasons, allowing moisture loss from or oxygen ingress into, the battery, both of which- make manufacturing cells incorporating such components less economical. It is the object of the present invention to provide a sufficiently air- tight battery seal wherein the positive terminal metal cap and washer are manufactured separately and is snap fit to give one piece as seal closure with terminal cap (referred to as dry cell seal ciosure hereafter) of its use in dry celL The said dry celt seat closure also prolongs shelf life effectively preventing moisture loss from, or oxygen ingress into the battery similar to dry cell incorporating mould cap for sealing. It is also an object of the present invention to provide a reliable dry cell seal closure, which is more economical to manufacture than the mould cap. It is also an object of the present application to disclose the construction of battery comprising said dry cell seal closure. It is also an object of the present invention to disclose that construction of battery comprising the said dry cell seal closure leads to better safety under foreseeable misuse than its construction comprising mould cap. SUMMARY OF THE INVENTION: In accordance with the present invention, an economically improved dry cell seal closure is disclosed which will effectively prevents the loss of moisture and oxygen ingress into the cell. The dry cell seal closure disclosed in the present invention comprising polyethylene ring washer with U shaped cross section having an outwardly projection at the top upper periphery of the washer to have an airtight placement on the open end of the cylindrical zinc can. The said ring washer has a central circular aperture with its inner lower edge chamfered at predetermined angle adapted to guide carbon rod through it into the metal cap. The positive terminal circular metal cap is snap fitted into the U shaped cross section of the ting washer, loeking-it into the groove to make as one-piece dry cell seal closure, The said dry cell seal closure disclosed in the present invention is more economical to manufacture compared to mould because of being made of separate component parts, requires less plastic material and further less wastage if one of the disclosedcomponent found defective at any stage of manufacturing to total assembly due to reuse of non defective component compared to whole component wastage in case of mould cap. Construction with respect to battery design while incorporating the dry cell seal closure of the present invention is also disclosed through figures. DETAILED DESCRIPTION OF THE INVETIONS This invention is now described with reference to the accompanying drawings. Fig I (a) = Front view of the metal cap A. Fig I (b) = Sectional view of the metal cap A at the XX in Fig I (a). Fig II (a)= Front view of the washer B. Fig II (b) = Sectional view of the washer B at YY in Fig II (b). Fig III (a) = Shows the dry cell seal closure unit with metal cap A and washer B assembled. Fig III (b) = Shows the sectional view of the dry cell seal closure at ZZ in. Fig III (a), being assembly of metal cap A and washer B. Fig IV (a) = Shows the sectional view of the dry cell with seal closure inserted in me zinc can from the top. Fig IV (b) = Shows the sectional view of the dry cell with rim of the zinc can 6 crimped inward supported by outside projection 3 and inward ridge 4 of the outer arm of me washer. The seal closure for dry cell comprises of the metal cap A and washer B assembled by snap fitting the flange 2 of the metal cap A in groove 5 of the washer B. This dry cell seal closure unit A and B is inserted in zinc can 6 from top and made to rest on the asphalt sealant 8. The upper rim 7 then crimped round the outer projection 3 and inner ridge 4 loeking the flange 2 of the metal cap in the groove 5 of the washer B. The dry cell further ribbed at 9 near top of the zinc can 6 as shown in the Fig IV (b). 1 is the positive terminal of the dry cell and 10 shows the negative terminal. The dry cell seal closure of this invention comprises a ring washer with U shaped cross section and a positive terminal circular metal cap, the said seal closure being fitted airtight at the top of zinc can by crimping and ribbing its upper extended edge and wherein the said ring washer being made of polyethylene having central circular aperture to guide the carbon rod through it and having the upper periphery of the outer arm projected outwardly adapted to fit tight in the zinc can which also support the rim of the can while crimping and further the said washer having inward ridge at upper edge of the said outer arm adapted to receive metal cap whose flange being snap fitted in the groove below the said ridge which also guide downward crimping edges of the can wherein the said positive terminal metal cap being made of brass having metal coating on it with shape adapted to fit on the carbon rod, having the lower flange snap fitted in the groove provided in the washer. The dry cell comprising of the seal closure described in this invention is having ring washer with central circular aperture adapted to receive the top of carbon rod making positive terminal with the metal cap wherein lower edge of the aperture is chamfered at predetermined angle. The peripheral flange of the seal closure described in the invention is made to rest air tightly on the asphalt sealant in the ean. The crimping of the upper rim of the zinc can round the upper projection and the inner ridge of the seal closure as described in the invention helps the terminal metal cap to get interlocked into the groove of the ring washer of the seal closure. The ribbing done at the top of the zinc can adapted to hold the seal closure airtight in it. The dry cell comprised of the seal closure as described in the invention is encased by an insulating PVC sleeve covering the sides of the zinc can in such that with only positive and negative terminal remain exposed, wherein the negative terminal may be either a bare zinc can bottom or with additional metal sheet adapted to fit on the bottom of the can. EXAMPLES Dry cells were constructed incorporating the seal closure and necessary design, changes as disclosed in the present invention and was compared against cells incorporating mould cap for its service life and safety test. The service life and safety under unforeseeable circumstances are very much a factor of active material composition and depolarizer mix weight in the cell. The dry cells constructed incorporating seal closure of the present invention and cells incorporating mould cap where in both depolarizer mix weight in the range of 7.5 gto 8.2 g having 3.5 g to 4.5 g active material with depolarizer mix moisture of 25 % to 30 % were used. The service life of the cells using seal closure of present invention found to be at par with the cells using mould cap; The test result of safety test has been listed in the table 1. WE CLAIM; 1. A dry cell seal closure comprising ring washer with U shaped cross section and a positive terminal circular metal cap, the said closure being fitted airtight at the top of zinc can by crimping and ribbing its upper extended edge and wherein the said washer made of polyethylene having central circular aperture adapted to guide carbon rod and the upper periphery of the washer being projected outwardly and having inward ridge, wherein said peripheral projection adapted to fit tight on the zinc can, also adapted to support the rim of the can while crimping and further the said washer having inward ridge at its upper edge to form a groove inside U shaped cross section adapted to receive flange of metal cap in the groove, also the ridge guide downward crimping edges of the zinc can and wherein the said positive terminal circular metal cap being made of brass having metal coating on it with shape adapted to fit on the carbon rod and its lower flange being snap fitted in the groove provided in the washer. 2. A dry cell seal closure as claimed in claim 1 wherein the ring washer having central circular aperture with lower edge being chamfered at predetermined angle adapted to receive the top of the carbon rod forming positive terminal with the metal cap. 3. A dry cell seal closure as claimed in any of claims 1 or 2 wherein the ring washer being made to rest on the asphalt sealant in the zinc can. 4. A dry cell seal closure as claimed in any of claims 1, 2 or 3 wherein the crimping of the can helps the terminal metal cap to get interlocked into the grooves provided in the ring washer of the seal closure. 5. A dry cell seal closure as claimed in any of claims 1,2,3 or 4 wherein the ribbing done on the zinc can adapted to hold the seal closure in airtight position. 6. A dry cell seal closure as claimed in any of claims 1,2,3,4 or 5 wherein the cell is encased by an insulating PVC sleeve covering the sides of the zinc can such that with only positive and negative terminal remain exposed, wherein the negative terminal may be either bare zinc can bottom or with terminal metal component adapted to fit at the bottom. 7. A dry cell having a seal closure as claimed in any of claims 1,2,3,4,5 or 6 where in the depolarizer mix weight shall be in the range of 7,5 g to 8,2 g having 3.5 % to 4.5 g active material with depolarizer mix moisture of 25 % to 30 % for optimum service life and safety under unforeseeable circumstances. 8. A dry cell seal closure as claimed in any of claims 1 to 7 and substantially similar to what is described in the complete specification here above with reference to the accompanying drawings. Dated this 26th day of June, 2003 For Matsushita Lakhanpal Battery India Ltd., A. C. Shah Dy. GM-Co. Secretary

Documents:

668-mum-2003-cancelled pages(09-11-2004).pdf

668-mum-2003-claims(granted)-(09-11-2004).doc

668-mum-2003-claims(granted)-(09-11-2004).pdf

668-mum-2003-correspondence(19-11-2004).pdf

668-mum-2003-correspondence(ipo)-(17-11-2003).pdf

668-mum-2003-declaration(27-06-2003).pdf

668-mum-2003-drawing(09-11-2004).pdf

668-mum-2003-form 1(04-02-2004).pdf

668-mum-2003-form 19(28-07-2003).pdf

668-mum-2003-form 2(granted)-(09-11-2004).doc

668-mum-2003-form 2(granted)-(09-11-2004).pdf

668-mum-2003-form 3(27-06-2003).pdf

668-mum-2003-form 5(28-07-2003).pdf

668-mum-2003-petition under rule 137(04-02-2004).pdf

abstract1.jpg