ELECTRIC STORAGE BATTERY

Abstract: Electric storage battery where the battery has an electrically insulating plastics material cup-shaped outer casing and an electrically conductive cup-shaped anode electrode easing part received within the plastics part to form a closed battery casing. The provision of the outer plastics material cup-shaped outer casing simplifies the assembly and reduces the number of manufacturing steps needed during the production of manganese dioxide electric storage batteries.

Description: ELECTRIC STORAGE BATTERY Technical Field This invention is concerned with improvements in and relating to electric storage batteries and more particularly with improvements in and relating to the casings of such batteries. Background Art It is known to manufactur alkaline manganese electric storage batteries by cold drawing a cup-shaped - steel container having an annular longitudinally extending wall and a closed end. The closed end may have a contact nipple integrally formed therein or secured to the exterior of the closed end and constituting the positive terminal. Within the container is an annulus of electrolytic material of manganese dioxide. This may be a single annular body or a plurality of such bodies stacked one on top of each other. Within the annulus is a paper separator which extends over the closed end of the container. A mass of a further electrolytic material of electrolyte is placed within the space defined by the separator. The open end of the container is closed by a disc having a central aperture, and a pressure relief aperture therein is closed by a body of wax. The pressure relief aperture is offset relative to the central aperture. A 'nail' is positioned with its stem extending through the aperture in the disc and into the electrolyte, the head of the nail overlying and nade fast with the battery casing and constituting the negative terminal. The container may be crimped to mechanically engage the disc and the whole assembly is peripherally shrink wrapped in a suitable synthetic plastic material, the edges of which, at the ends of the container extend radially inwardly. The shrink wrap material is itself encompassed by a sheet of suitably lithographed r^etal sheet, the ends of which are once again turned radially inwardly. If desired an insulating disc may be provided on the external surface of the closed end of the container, that disc having a central aperture through which the contact nipp-le extends and that disc being clamped against the closed end by the lithographed metal outer. Such a battery has proved to be successful. However, a substantial part of the cost therein lies in the complicated assembly procedures for all the necessary components. It is therefore an object of this invention to provide a battery of this type in which the cost is reduced and wherein assembly of the components will be able to be adopted to mass production techniques- Disclosure of the Invention Therefore according to the present invention there is provided an electric storage battery having a plastics material cup shaped outer casing part and a metal cup shaped anode electrode casing part received within the plastics part to form a closed battery casing, an annular body of electrolytic material and a further electrolytic material retained therein, said annular body of electrolytic material being in electrical contact with the inside walls of said metal part, and the further electrolytic material being in electrolytical contact with the inside walls of said annular body of electrolytic material; the closed end of said metal part forming an electrical conductor of one battery terminal and the electrode forming an electrical conductor of the other battery terminal. In one embodiment the plastics part is a preform. In an alternative arrangement the plastics part may be an extruded synthetic plastics sleeve, the closed end of which may be formed by radially deforming one end of the side walls or by providing a disc like member at one end of the sleeve. Brief Description of Drawings In order that the invention may be better understood there will now be described some embodiments thereof, given by way of example only wherein:- Figure 1 is a side cross-sectional view of a known alkaline manganese storage battery. Figure 2 is a side cross-sectional view of an outer casing part of one preferred embodiment of the invention. Figure 3 is a side view in part cross-section of a prior art 'chemicalpack' used in the preferred embodiment of Figure 2. Figure 4 is a side view in part cross-section showing how the 'chemical pack' of Figure 3 is fitted within the outer casing part of Figure 2. Figure 5 is a side view in part cross-section showing an alternative embodiment to that in Figures 2 to 4. Figure 6(a) is a side view in part cross-section of the negative end of an even further embodiment. Figure β(b) is a close-up side view in cross- section of an end edge of the outer casing part of Figure 6(a). Figure 7 is a side cross sectional view of an even further alternative embodiment and Figure 8 is a sectional view taken along line 8-8 of Figure 7. Best Mode of Carrying Out Invention The known alkaline manganese dioxide electric storage batteries as shown in Figure 1 have a cold drawn cup-shaped steel casing part 1 having an annular long¬ itudinally extending wall 3 and a closed end 5. The closed end 5 has a contact nipple 7 secured to the exterior of the closed end 5. This constitutes the positive term¬ inal. Within the cup-shaped casing part 1 is an annulus of electrolytic material of manganise dioxide 9 comprising a pluraltiy of bodies one on top of each other. Within the annulus 9 is a paper separator 11 which extends over O PI the closed end of the casing part 1. A mass of a further electrolytic material of electrolyte 13 is placed within the space defined by the separator 11. The open end of the casing part 1 is closed by a plastics material disc 15 having a central aperture 17, and a pressure relief aperture 19 therein is closed by a body of wax 21. The pressure relief aperture 19 is offset relative to the central aperture 17. A 'nail' 23 is positioned with its stem extending through the aperture 17 in the disc 15 and into the electro¬ lyte 13, the head 25 of the nail 23 made fast with the outer casing 27. The head 25 constitutes the negative terminal of the battery. The casing 1 is crimped to mechanically engage the disc 15 and the whole assembly is peripherally shrink wrapped in a suitable electrically insulating synthetic plastics material 28, the edges of which, at the ends of the casing 1 extend radially inwardly. The shrink wrap material- 28 is itself en¬ compassed by the outer casing 27 which is a metal which is suitably lithographed with the Trade Mark of the battery manufacturer. The ends of the outer casing 27 are turned radially inwardly to hold the head 25 in position. An electrically insulating annular disc 29 may be provided on the external surface of the closed end 5 of the casing 1, that disc 29 having a central aperture through which the contact nipple 7 extends and that disc 29 being clamped against the closed end by ■the outer casing 27. A further electrically insulating disc 33 is provided at the negative end of the battery to electrically insulate the head 25 of the nail 23 from the casing 1. The shrink wrap plastics material 28 electrically isolates the outer casing 27 from the negative and positive terminals. A space 35 is provided between the disc 15 and the head 25 of the nail 23. This space 35 is used to store electrolytic materials and/or gases which may generate within the battery during excessive use of PI the battery and cause a pressure temperature build-up within the battery sufficient to displace the body of wax 21. The disc 33 is of.'a suitable material 35 to absorb any electro¬ lyte material that may seep through the aperture 19. A first embodiment of the invention is shown in Figures 2, 3 ,ancl 4. Figure 3 shows a chemical pack which comprises, the cup-shaped steel casing part 1 as shown in Figure ' 1 with the contact nipple 7 thereon and the disc 15.. It also contains the manganese dioxide electrolytic material 9, the paper separator 11 and the electrolyte 13.. The materials within the casing 1 have not been shown -as they are identical with that shown in Figure 1. In the present embodiment the outer casing of the battery' is provided by a cup-shaped synthetic plastics material outer casing part 50. The casing 50 may be made by injection moulding or by compression moulding. Preferably a polypropylene material is used, however, any suitable plastics material which has an electrically insulating characteristic could also be used. The casing 50 has side walls 51 and a closed end 53. The closed end 53 is situated a short distance inwardly from the extreme upper end as shown in Figure 2. The closed end 57 has a central opening 55 therein through which the nail 23 can be inserted. The lowermost end of the casing 50 as shown in Figure 2 is open. The internal diameter of the casing 50 is the same as the external diameter of the casing 1 so as to ' allow for sliding tight fitting engagement therewith. At the closed end of the casing 50 there is provided a recess 57. The recess 57 is circular and has undercut shoulder portions 59. When the battery is assembled, the chemical pack as shown in Figure 3 is inserted within the casing 50 by being relatively pushed thereinto, ϊt should be noted that the casing 50 is an open cup-shaped casing whilst the casing 1 is also a cup-shaped casing. The closed ends of the respective casings 50 and 1 define, when the outer casing 50 is inserted over the casing 1, the respective end portions of the battery. The completed battery assembly is shown in Figure 4. Here it can be seen that the battery chemical pack is inserted within the outer casing 50 and that the open end side walls 61 near the open end are deformed radially inwardly to secure the battery chemical pack within the outer casing 50. It should be noted that a space 35 is provided between the portion 53 closing the end of the outer casing 50 and the end of the plastics disc 15. This space 35 is provided for the same purpose as the embodiutent in the prior art. In the preferred construction herein the nail 23 has a different shaped heat 25' to that shown in Figure 1. Here the head is a disc of metal which is welded or otherwise electrically attached to the nail 23. The outer circumferential portions of the head 25' depend downwardly as shown by shoulders 63 and then return upwardly as defined by shoulders 65. It can be seen therefore that the shoulders 65 and 63 deform radially inwardly whilst the shoulders 59 of the outer casing 50 deform radially outwardly during insertion of the nail. The dimensioning of the shoulders 65 is such that the extreme circumferentially outermost edges engage with the shoulders 59 and the snap-lock hold the head 25' within the recess 57. This in turn holds the nail 23 within the battery. The outer casing part 50 may be of a clear plastics material which is coated with printing on either the internal or external surfaces of the side walls 51 and have regions therein which are clear. The casing 1 may be polished so as to have a bright chrome like appearance and therefore the chrome like appearance can be seen through the clear portions of the casing 50 and if the printing is such that the clear portions define trade marks then it would appear to an observer that the battery has a metal appearance. Other forms of - t)S O providing labelling of the battery could be envisaged. For example, after polishing the casing, it may be printed itself and then coated with a protective layer such as a lacquer or varnish. Referring now to Figures 5, 6(a) and 6(b) there is shown an alternative embodiment of the present invention. In this embodiment instead of the battery pack being provided as a substantially sealed unit the outer casing 50 closes the battery pack itself to retain the electro¬ lyte within the casing 1. Therefore the casing 1 is the same as in the prior art embodiment and has all the electrolyte materials therein as per the prior art embodiment. Instead of closing the open end of the casing 1 with a plastics disc 15 it is closed by the closed end 70 of the outer casing 50. In this embodiment the outer casing 50 still has inclined shoulders 59 which define a recess 57 at the closed end of the outer casing 50. The head 25' of the nail is the same construction as shown in Figure 4. It is noted that in this con¬ struction the outer casing 50 has an annular recess 71 extending parallel with the side walls 51, Thus, the open end of the casing 1 has the side walls 3 received within the recess 71. Typically, the dimensioning of the recess 71 is such to require a force fit of the outer casing 50 over the casing 1. An adhesive material not shown can be used to hold the outer casing 50 to the inner casing 1-and to provide a seal at the closed end of the outer casing 50 where it mates with the side walls 3. It is noted that the open ends of the outer casing 50 are turned radially inwardly to assist holding the casing 1 within the outer casing 50. The radially inturned ends may be achieved by rolling the side wall 3 radially inwardly over the closed end of the casing 1. Figures 6(a) and 6(b) show an alternative embodiment using the same basic principle as shown in the embodiment of Figure 5. Here the open ends of the casing 1 have the side walls radially inturned as shown by portion 75. OM?I In this embodiment the recess 71' is equal to the radial width of the inturned portion 75. This is shown clearly in Figure 6(b). Thus, the radially inturned end 75 can be pushed into the recess 71' . A passageway 76 is provided in the recess 71' in order to allow air to vent therefrom during the insertion of the inturned portion 75 thereinto. This aids assembly. In this embodiment, the head 25' ' of the nail 23 has a side wall 77 which extends downwardly from the rear main body part 78 and has a radially expanded portion 79. The free edge of the radially expanded portion 79 is inwardly curved at 81. Thus, in this embodiment, when the head 25' ' is inserted, the radially expanded portion 79 deforms the wall surfaces 83 around the internal portion of the recess 57, so as to move under the radially inturned portion 75 of the wall 3. Thus the head 25 ! l is - retained to the battery and also the casing 1 is retained to the outer casing 50. The open end of the casing 50 may be rolled around the positive end of the battery as has been shown in Figure 5. Figures 7 and 8 show a further embodiment where for example a 'D' size battery can be made with a *C* size chemical pack. In this construction the chemical pack 1 is of the same type as disclosed in the embodiments of Figures 5 and 6, as the open end is not sealed by a disc 15 but by a part of the outer casing 50. In this construction the casing 1 is of a size for a 'C size battery. It can therefore be seen that the nipple 7 is of a much larger size and in this embodiment it is of the size used in a 'D' size battery. " The closed end 91 of the outer casing 50 has an inwardly inclined portion 93 which defines the recess 57. The inwardly inclined portion 93 terminates with the portion 95 which closes the cup-shaped outer casing 50. The portion 95 terminates with a boss part 97 which has a central opening 99 therein through which the nail 23 can pass to enter the electrolyte within the casing 1. The boss 97 is supported by webs 101. The inclined portion 93 has a skirt 105 extending therefrom in a direction parallel with the side wall 3 of the outer casing 50. The skirt 105 is a circumferentially extending skirt the internal diameter of which is sized to tightly receive the casing 1. The skirt 105 thus centrally locates the casing 1 within the outer casing 50. Additionally, there are a plurality of longitudinally extending ribs 109 on the inside walls of the outer casing 50. These ribs 109 serve to provide rigidity to the outer surface of the casing 50 and also rigidly support the casing 1 therein. In this embodiment the open end of the side wall 3 of the casing 1 are radially inwardly turned as shown for the embodiment of Figure 6. Here those portions are designated by numerals 75'. The innermost surfaces of the inclined portions 93 define a circumferential recess 110, radially inwardly of the skirt 105, within which the rolled-over portion 75' of the inner casing 1 is received. The innermos surface of the inclined portion 93 adjacent the portion 95 is then deformed radially outwardly by a metal retaining ring 113 so as to deform the plastics material radially outwardly, thereby closing the circumferential recess 110 underneath the rolled-over portion 75' of the casing 1. The retaining ring 113 has inwardly inclined side surfaces 115 which terminate with a snap engaging curved surface part 117. A passageway 111 is provided in the recess 110 to allow air to vent during the assembly of the rolled-over portion 75 in the recess 110. In this embodiment the head 25' • ' terminates with an outer folded portion 121, the radially outermost surfaces of which are inclined in a direction so that the free ends 124 are radially of greater diameter than that of the tail end 123. A circumferential recess 131 is provided at the negative end of the outer casing 50 and the angle of inclination of the side walls thereof corresponds with that of the inclination of the radially outermost part of the folded portion 121. Thus, the head 25 ' ' ' can be bumped into the recess 131 so as to snap lock hold the head 25' '' and the nail 23 in position. The open end of the outer casing 50 can have the ends rolled over as shown by 133 to engage with an upturned part 135 of the nipple 7'. Thus, the nipple 7' is securely retained within the outer casing 50. In a modification of the embodiment shown in Figures 7 and 8 the portion 95 may be suitably shaped to receive and hold an already closed chemical pack as distinct from physically closing the casing 1. In a modification of all the embodiments shown the body of wax 21 may be replaced by a rupturable mem¬ brane of the plastics material forming the portion which closes the end of the outer casing 50 or- of the disc 15 which closes the chemical pack. fOSftE

Claims: ' CLAIMS : 1. An electric storage battery having an electrically insulating plastics material cup-shaped outer casing part and an electrically conductive cup-shaped anode electrode • casing part received within the plastics part to form a closed battery casing, an annular body of electrolytic material and a further electrolytic material retained therein, said annular body of electrolytic material being in electrical contact with the inside walls of said metal part, and the further electrolytic material being in electrolytical contact with the inside walls of said annular body of electrolytic material; the closed end of said outer casing part having an electrode which extends therethrough and into said further electrical material whereby to provide a negativ * electrode for said battery, said closed end of said metal casing part forming a positive electrode for said battery. 2. An electric storage battery as claimed in claim 2 wherein the open end of said metal casing part is closed by a disc like member of electrically insulating material.- 3. An electric' storage battery as claimed in claim 2 wherein a chamber is provided between the so closed end ..of said outer casing part and said disc member, and where¬ in said disc like member has a sealed but rupturable passageway means extending between said chamber and said further electrolytic material, said sealed but rupturable passageway means being rupturable on generation of excessive temperature and/or electrolytic gases within said metal casing part to allow said gases or electro¬ lytic material to vent into said chamber. 4. An electric storage battery as claimed in any one of the preceding claims wherein said electrode which extends through the closed end of said outer casing part is electrically connected with disc-like electrically conductive member which is the negative terminal of said battery. 5. An electric storage battery as claimed in claim 4 wherein the outer circumferential region of said disc-like electrically conductive member and the closed end of said outer casing part are shaped to permit snap- lock engagement of said disc-like electrically conductive member thereto. 6. An electric storage battery as claimed in claim 1 wherein the open end of said metal casing part is closed . by engaging with the closed end of the outer casing part. 7. An electric storage battery as claimed in claim 6 wherein the closed end of said outer casing part has an internal circumferentially extending recess into which the open end of said metal casing part is received whereby to close said metal casing part. 8. An electric storage battery as claimed in claim 7 wherein the ends of metal casing part are turned over to extend in a radial direction, said recess being of sufficient width in the radial direction to allow. the. turned over ends to be received therein and wherein said metal casing part is retained to the outer casing part by the side walls of the recess being deformed-to locate behind the turned over ends. 9. An electric storage battery as claimed in claim 8 wherein the side walls of said recess are deformed by a rigid member which has a radial dimension sufficient to enable force fitting in a direction longitudinally into the battery part, the turned over ends to so deform said side walls of said recess. ' 10. An electric storage battery as claimed in claim 9 wherein said rigid member is an electrically conductive disc like member which is electrically connected to said further electrode and is the negative terminal of said battery. 11. An electric storage battery as claimed in claim 10 wherein a chamber is provided between said electrically conductive disc and the closed end of said outer casing part and wherein the closed end of said outer casing part has a sealed but rupturable passageway means extending between said chamber and said further electro¬ lytic material, said sealed but rupturable passageway means being rupturable on generation of excessive temp¬ erature and/or electrolytic gases within said metal casing part to allow said gases or electrolytic material to vent into said chamber. 12. An electric storage battery as claimed in claim 9 wherein said rigid member is rigid annular ring 13. 13. An electric storage battery as claimed in claim 12 wherein said further electrode is electrically connected with an electrically conductive disc like member which forms the negative terminal of said battery. 14. An electric storage battery as claimed in claim 13 wherein a chamber is provided between said disc like member and the closed end of said outer casing part and wherein the closed end of said outer casing part has a sealed but rupturable passageway means extending between said chamber and said further electrolytic material, said sealed but rupturable passageway means being rupturable on generation of excessive temperature or electrolytic gases within said metal casing part to allow said gases or electrolytic material to vent into said chamber. 15. An electric storage battery as claimed in claim 13 or claim 14 wherein the outer circumferential edges of said disc like member are shaped for snap lock engaging with suitably shaped surfaces at the closed end of said - outer casing part. 16. An electric storage battery as claimed in any one of the preceding-claims wherein the outer casing part has an external diameter substantially larger than that of the external -.diameter of said metal casing part and wherein rib means are provided which extend between the side walls of said outer casing part and the metal casing part to support the side walls of said metal casing part against the side walls of said outer casing part whereby to enable a larger diameter battery to be provided with a substantially smaller diameter metal casing part. 17. An electric storage battery as claimed in any one of the preceding claims wherein the open end of said outer casing part is deformed radially inwardly whereby to assist holding of said metal casing part within said outer casing part. OMPI

Inventors: GARWOOD ANTHONY J
Applicants: GARWOOD ANTHONY J, MACGAR HOLDINGS PTY LTD
Application year: 1981
Main classification: H01M2
IPC codes: H01M2