HERMETIC TERMINAL ASSEMBLY AND METHOD OF MANUFACTURING SAME

Abstract: The terminal pin and end closure structure for an hermetic terminal assembly includes an apertured end closure (2) with a peripheral wall (12) surrounding the aperture (6) to extend at preselected angle from the end closure (2), the aperture (6) being covered by a sealed terminal pin (19) carrying sealing member (13) which is sealed to the extended peripheral wall (12).

Description: The present invention relates to hermetic terminal assembly structure and a method of making the same and particularly to terminal pin and end closure structure which can be used with hermetic terminal assemblies such as lithium batteries. It is well known in the art to place an apertured cover in a fixture, the fixture further supporting in the cover aperture a terminal pin surrounded by an annular bead of glass or glass sinter extending from the pin to the aperture wall, the loaded fixture being heated to the melting point of the glass to bond the glass to the cover and to the pin. More recently, to reduce space, time and energy requirements and to avoid cumbersome manufacturing techniques, a universal seal of the eyelet type has been provided in the form of a pin carrying eyelet which can be readily oriented in either of two positions in sealing relation with the aperture of the cover for efficient and economical assembly and welding. This known type universal seal is disclosed in US-A-4 603 095. The pin carrying eyelet has a chamfered edges. For fuse welding the eyelet to the end closure or cover one of the chamfered edges is placed in contact with a sharp arras defining the margin of the aperture in the end closure or cover. It is also known from US-A-3 219 753 and 4 213 004 to provide surface to surface contact between a pin carrying eyelet and a cover to which the eyelet is to be welded. The glass seal is spaced axially of the pin from the weldment between the eyelet and the cover. The object of the invention is the provision of a terminal pin and end closure structure, and method of manufacturing the same, providing an improved strong fuse weld seal between the eyelet and the end closure while maintaining optimum compactness. In accordance with the invention, to achieve this, there is provided a terminal pin and end closure structure for an hermetic terminal assembly, comprising an end closure including a main body portion having an aperture therein, a projection surrounding the aperture, being integral with the main body portion and extending at an angle with respect thereto, and a substantially flat eyelet geometrically sized to conform with and totally cover said aperture in said end closure, said eyelet having opposed parallel side faces with an aperture disposed therethrough, and a chamfered peripheral edge adjacent at least one side face, with said chamfered peripheral edge being fuse welded in sealed relation to said projection, characterized in that said projection is an extended peripheral wall portion presenting inner and outer edges at its extremity and that the chamfered edge abuts said inner edge of said extended peripheral wall portion providing line contact therebetween along the entirety of the circumferential extent of the chamfered edge and the inner edge of said extended peripheral wall portion. In further accordance with the invention there is provided a method of manufacturing a terminal pin and end closure structure for an hermetic terminal assembly, comprising the steps of providing an end closure, forming an aperture in said end closure and around said aperture a projection integral with the material of the end closure and extending at an angle with respect to the main body portion of the end closure, providing a flat eyelet, forming a chamfered edge portion at the outer periphery of said eyelet and sealingly securing a terminal pin in an aperture of said eyelet, positioning said eyelet on said end closure so that it covers the aperture in said end closure with the chamfered edge portion in contact with said projection of the end closure, and fuse welding the eyelet at said chamfered edge portion to said projection of said end closure, characterized by forming said projection around the end closure aperture as an extended peripheral wall portion having inner and outer edges at its free extremity, and the positioning step comprises placing said eyelet such that said chamfered edge portion abuts said inner edge of said extended peripheral wall portion to provide line contact therebetween along the entirety of the circumferential extent of the chamfered edge and the inner edge of said extended peripheral wall portion. The present invention provides an improved structural assembly and method of manufacture over more recent techniques gaining the advantages of reducing space, time, material and energy requirements, avoiding cumbersome manufacturing steps and at the same time improving the joining of a pin carrying sealing member, such as an eyelet to the cover, increasing both the strength of the jointure and the structural support and assured positioning of the terminal pin relative the cover to which it is assembled. Further, the present invention allows for the use of thinner covers thus contributing to overall size and weight reduction of the hermetic terminal assembly without sacrificing strength or terminal pin support, providing an assembly particularly suited to lithium type batteries. Thus, the present invention provides both a strong and uniform seal of the sealing member to the cover with an optimum of space, time and energy requirements in a straightforward and economical manner. The terminal pin and end closure structure and its method of manufacturing will now be described in greater detail with reference to the drawings, wherein: Figure 1 is a plan view of an apertured end closure for a hermetic terminal assembly; Figure 2 is a cross-sectional view of the end closure of Figure 1 taken in a plane through line 2-2 of Figure 1; Figure 3 is a view similar to that of Figure 2, disclosing the forming tool in operative engagement with the aperture in the main body of the end closure to form a protuberance in the form of an extended peripheral wall portion surrounding the aperture; Figure 4 is an enlarged cross-sectional schematic view similar to Figure 3, disclosing a sealing member in the form of a terminal pin carrying eyelet conforming with and covering the aperture with the chamfered edge face of the eyelet abutting an edge of the extended peripheral wall and electrical resistance welding tools proximate thereto to sealingly join the eyelet to the wall; Figure 4a is an enlarged view of a portion of the structure of Figure 4 disclosing details of the chamfered edge face of the eyelet abutting the extended peripheral wall; Figure 5 is a partial cross-sectional view similar to Figure 4, disclosing a laser welding tool proximate the abutting chamfered edge face of the eyelet and the edge of the extended peripheral wall portion to sealingly join the eyelet to the wall; Figure 6 is a partial cross-sectional view similar to Figure 4, disclosing a rotatable inertial welding tool positioned for engagement with an appropriately slotted eyelet, the chamfered edge face of which abuts the edge of the extended peripheral wall portion to be sealingly joined by inertial welding; Figures 7A and 7B through Figures 9A and 9B disclose various slotting and gripping arrangements for eyelets for driving connection to an appropriate collet of an inertial welding tool; and, Figure 10 is a cross-sectional view of an end closure cover and eyelet assembly arrangement similar to that of Figures 4, 5 and 6, disclosing an assembly after jointure. As can be seen in Figures 1-4 of the drawings, the novel end closure 2 as disclosed includes a circular main body portion 3 having a peripheral rim 4 extending normally therefrom and a circular opening or aperture 6 centrally disposed therein. It is to be understood that other shapes of end closures, apertures and number of apertures per end closure can be utilized depending upon the shape and construction of the hermetic assembly housing (not disclosed) with which the end closure is associated. The end closure is formed from a suitable fusible stock material and, when the end closure is to be for lithium type battery assemblies, advantageously is formed from a suitable thin metallic material such as stainless steel strip stock, designated commercially as 304 L SS having a thickness of approximately 0.25 ± 0.025 mm (0.010 ± .001 inches), the main body 3 of the end closure 2 having substantially opposed planar surfaces 7 and 8, one of which serves as an inner surface and the other an outer surface depending upon end closure assembly to the housing. Referring particularly to Figure 3 of the drawings, surface 7 of end closure 2 is shown resting on the upper edge face of annular support member 9 with a cylindrical forming tool 11 having displaced the metal of main body portion 3 surrounding aperture 6 and extending through aperture 6 to form an integral protuberance or peripheral wall portion 12 extending normally from surface 8 to surround aperture 6. The distance of extension of peripheral wall portion 12 depends upon the amount of the diameter of aperture 6, it being important that this distance be properly preselected to provide an appropriate amount of metal for the eyelet sealing jointure described hereinafter. It is to be understood that the present invention is not to be considered as limited to the specific method of forming protuberance or peripheral wall 12 as hereinabove described. For example, it would be possible to form peripheral wall 12 by material extrusion or by punching an aperture 6 through main body portion and reducing the arras resulting from the metal displacement by the punching step a preselected amount to provide the desired size peripheral wall 12 surrounding aperture 6. Referring to Figure 4, a terminal pin carrying sealing member in the form of an annular eyelet 13 is disclosed. Eyelet 13, like end closure 2, can be formed from a suitable fusible material companionable with the fusible material of end closure 2 and in lithium type battery assemblies advantageously is of the same stainless steel stock as the end closure 2. Eyelet 13 has substantially flat, parallel surfaces 14 and 16, is circular and is sized to conform with and cover aperture 6 in end closure 2. The eyelet 13 has a central aperture 17 defined by an inner cylindrical wall 18 to which a terminal pin 19 is bonded by means of a suitable seal 21, which can be of a preselected glass formulation. The outer margins of the eyelet 13 are defined by an outer wall 22, perpendicular to parallel planar eyelet surfaces 14 and 16 and chamfered perimetric edge faces 23 and 24, extending at mirror-image angles from the opposite perimetric edges of outer wall 22 to eyelet surfaces 14 and 16 respectively. As aforenoted, the angles of the chamfered faces can be identical and the chamfers symmetrical so that the eyelet is symmetrical on either planar surface. In Figure 4, it is to be noted that chamfered edge face 23 abuts against the inner free edge of peripheral wall 12, it being understood that it would also be possible to have chamfered edge face 24 so abutting the inner free edge of peripheral wall 12, the abutment, in either case, forming a line contact between the chamfered edge face and the peripheral wall edge. To joiningly seal eyelet 13 positioned to abut peripheral wall 12, any one of several types of joining steps can be utilized. In Figure 4, charged electrodes 26 and 27 are shown positioned above and below the assembled eyelet and end closure. Parts of the electrodes are suitably anodized to minimize possible arcing between electrodes, the peripheral wall 12 further serving as an electrode spacer to minimize arcing. When a suitable resistance welding current is applied, the wall 12 provides a weld nugget to fuse joint the eyelet to the main body portion 3 of end closure 2. Since an ample amount of fusing metal can be provided through an appopriately preselected protuberance or peripheral wall 12, it is possible to make a uniform, securely sealed welded jointure along the entire area even if the main body portion 3 of the end closure 2 should be selectively very thin. The inside peripheral wall 12 serves to provide a high resistance weld area and thus high local current density to allow a quick and thorough weld without damage to seal 21 for eyelet 13. In forming the seals for eyelets 13, eyelets 13 are positioned in cavities in a fixture with one of either of the flat sides of each eyelet resting on the bottom face of the cavity. An annular glass bead 21 is inserted in eyelet aperture 17 and a terminal pin 19 is inserted in the bead opening to project a preselected distance from surfaces 14 and 16. The loaded fixture is then heated in an oven or furnace to fuse bead 21 to pin 19 and eyelet inner wall 18. When the distance that pin 16 projects from surface 14 and 16 is equal, it makes no difference which face of eyelet 13 abuts the edge of wall 12. Referring to Figure 5, a chamfered eyelet 13 is shown with a chamfered edge face 23 abutting the inner free edge of peripheral wall 12 of end closure 2. To join the abutting eyelet and wall, laser gun 29 is disclosed focusing at the line of abutting contact to fuse and securely seal the entire area along the line of abutment. Referring to Figure 6, a view similar to that of Figure 5 is disclosed only in place of laser gun 29, rotatable collet 31 is shown with its drive pins 32 positioned to be engaged in appropriate gripping means in the form of recessed slots in eyelet 13 to rotate the eyelet 13 and thus inertially weld the eyelet 13 to the peripheral wall 12 along the line of abutting contact to fuse and securely seal the entire area along the line of abutment. As can be seen in Figures 7A and 7B through Figures 9A and 9B, various groove type gripping arrangements can be provided in eyelet 13 for drive pins 32. In Figures 7A and 7B, four equally spaced slots 33 and 34 are provided on each side of the eyelet 13 with slots 34 being offset 45 o from slots 33 in circular formation around the center of the eyelet. In Figures 8A and 8B the gripping recesses are in the form of three equally spaced dimples 36 and 37 provided on each side of eyelet 13 with dimples 36 being offset 60 o from dimples 37 in circular formation around the center of the eyelet. In Figures 9A and 9B a stepped grip collar 38 is provided on either side of the eyelet 13 which in turn can be matingly engaged by an appropriately fashioned chuck member (not shown) to be mounted on rotatable collet 31. In this regard, grip collar 38 can be multi-sided if desired to facilitate gripping by an appropriately multi-sided female chuck member mounted on collet 31. From the description above for Figures 7A and 7B through Figures 9A and 9B, it can be seen that either side of eyelet 13 can be driven by a suitable rotatable collet to permit efficient and uniform inertial welding along the area of contact between eyelet 13 and peripheral wall portion 12. It is to be understood that various other gripping patterns can be employed on the eyelet for collet driving purposes. For example, a foraminous system of meshing merlons and crenals could be employed between either side of the eyelet and collet to insure positive drive without slippage. Referring to Figure 10, an enclosure 2 is disclosed in final form with the eyelet 13 fastened to the closure 2 through wall 12 which has almost been entirely melted to provide a uniform, securely sealed welded jointure along the entire area of contact between wall and eyelet. From the description set forth above, it is to be understood that although the present invention lends itself to the effective utilization of very thin end closure structure, the size and geometry of the closure is otherwise immaterial as long as the closure aperture and peripheral wall are sized to permit the sealingmember such as an eyelet to be securely welded as described. Similarly, the dimensions of the eyelet and terminal pin can be varied, as can the angle of edge face chamfer and the angle of peripheral wall portion 12 to main body portion 3 of end closure 2. As abovenoted, the end closure and eyelet advantageously can be made of compatible stainless steel but other type metals or conceivably even fusible plastics can be employed.

Claims: A terminal pin and end closure structure for an hermetic terminal assembly, comprising an end closure (2) including a main body portion (3) having an aperture (6) therein, a projection surrounding the aperture (6), being integral with the main body portion (3) and extending at an angle with respect thereto, and a substantially flat eyelet (13) geometrically sized to conform with and totally cover said aperture (6) in said end closure (2), said eyelet (13) having opposed parallel side faces (14, 16) with an aperture (17) disposed therethrough, and a chamfered peripheral edge (23) adjacent at least one side face (14), with said chamfered peripheral edge being fuse welded in sealed relation to said projection, characterized in that said projection is an extended peripheral wall portion (12) presenting inner and outer edges at its extremity and that the chamfered edge (23) abuts said inner edge of said extended peripheral wall portion (12) providing line contact therebetween along the entirety of the circumferential extent of the chamfered edge (23) and the inner edge of said extended peripheral wall portion (12). Terminal pin and end closure structure according to claim 1, characterized in that said extended peripheral wall portion (12) extends normal to said main body portion (3). Terminal pin and end closure structure according to claim 1, characterized in that said eyelet (13) has gripping recesses (33, 34; 36, 37) on at least one side face (14, 16) thereof to be drivingly engaged for inertial welding thereof to said extended peripheral wall portion (12). Terminal pin and end closure structure according to claim 1, characterized in that both side faces (14, 16) have a chamfered peripheral edge (23, 24). Terminal pin and end closure structure according to claim 1, characterized in that said eyelet (13) is joined by resistance welding to said peripheral wall portion (12). Terminal pin and end closure structure according to claim 1, characterized in that said eyelet (13) is joined by laser welding to said end peripheral wall portion (12). Method of manufacturing a terminal pin and end closure structure for an hermetic terminal assembly, comprising the steps of: providing an end closure (2), forming an aperture (6) in said end closure (2) and around said aperture (6) a projection integral with the material of the end closure (2) and extending at an angle with respect to the main body portion (3) of the end closure (2), providing a flat eyelet (13), forming a chamfered edge portion (23) at the outer periphery of said eyelet (13) and sealingly securing a terminal pin (19) in an aperture (17) of said eyelet (13), positioning said eyelet (13) on said end closure (2) so that it covers the aperture (6) in said end closure (2) with the chamfered edge portion (23) in contact with said projection of the end closure (2), and fuse welding the eyelet at said chamfered edge portion to said projection of said end closure (2), characterized by forming said projection around the end closure aperture (6) as an extended peripheral wall portion (12) having inner and outer edges at its free extremity, and the positioning step comprises placing said eyelet (13) such that said chamfered edge portion (23) abuts said inner edge of said extended peripheral wall portion (12) to provide line contact therebetween along the entirety of the circumferential extent of the chamfered edge (23) and the inner edge of said extended peripheral wall portion (12). Method according to claim 7, characterized in that said aperture (6) with said peripheral wall portion (12) are punch formed in said end closure (2). Method according to claim 7, characterized in that said aperture (6) with said peripheral wall portion (12) are extrusion formed in said end closure (2).

Inventors: BOWSKY, BENJAMIN, BURROWS, LARRY GENE, HONKOMP, GLENN ANTHONY, WILSON, EDWARD EUGENE
Applicants: EMERSON ELECTRIC CO.
Application year: 1987
Main classification: H01M2
IPC codes: F16J15, H01M2, H01B17, H01L21