Abstract:
The provision of improved venting in battery cells by way of better preventing pressure buildup in the cells. Via different variants of the present invention, the following advantages are achieved:
       Gas can escape from the cell without clogging the vent;   gas buildup is avoided while the venting valve can operate in a consistently reliable manner;   the solutions presented are sufficiently versatile as to be applicable to a variety of cells on the market; and   the risk of explosion is virtually eliminated.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to computer systems and to methods and arrangements for establishing customer/user defaults in computer systems. 
     BACKGROUND OF THE INVENTION 
     Rechargeable Lithium-Ion batteries are used extensively in notebook computers, cell phones and many other types of portable equipment primarily because of their relatively low cost and high energy storage capability. However, increasing demands to package more power into a given cell size are creating a strain on practical and technological limits for some geometries. This is evidenced by a marked increase in safety-related incidents where cells have has exploded, ruptured, or vented (i.e., undergone a forced expulsion of gases). The safety hazards from such incidents, although rare, include the potential for causing a fire and the risk of burns and other injury from projectiles and ejected cell contents. This problem has in fact subjected some battery vendors and equipment manufacturers to a number of well-publicized recalls. 
     Generally, a safety relief valve (or vent) represents one of the most important safety mechanisms on any cell. All cylindrical cells are required by law to be fitted with pressure relief devices designed to relieve excess gas pressure. The function of a safety relief valve (vent) is to keep a cell from rupturing in the unlikely event of excessive pressure buildup. 
     Generally, all current production of Li-Ion batteries involves the provision of venting mechanism at the top of the cell, which provides a safe manner of releasing excess internal pressure and preventing the cell from reaching excessively high pressure and rupture. This venting mechanism needs to be capable of operating at all times, especially during internal pressure buildup. Once a condition occurs that causes the pressure in a cell to rise to a dangerous level, the vent may be the only device at hand to prevent a catastrophic failure. 
     Historically, it has been shown that in order for a venting mechanism to work properly, not only should the vent be able to release the buildup gas pressure as fast as possible, but nothing should block the discharge channel, that is, the passage or passages through which gas must pass to reach the operating parts of the safety relief device. 
     Extensive pinpoint heating tests have shown that some cells are prone to rupture even before thermal runaway (i.e., a rapid increase in temperature), whence a supporting washer collapses and clogs the main venting orifice on the terminal disc (see description of  FIG. 2  further below). While under normal conditions the valve “bursting disc” opens and the gas flows through the opening and exits the cell through terminal orifices, under abnormal conditions the gasket expands and collapses against the terminal and clogs the vent orifices, thereby leading to cell rupture. 
     In view of the foregoing, a growing and compelling need has been recognized in connection with improving upon the discussed shortcomings and disadvantages, among others. 
     SUMMARY OF THE INVENTION 
     Broadly contemplated herein, in accordance with at least one presently preferred embodiment of the present invention, is the provision of improved venting in battery cells by way of better preventing pressure buildup in the cells. 
     In summary, one aspect of the invention provides an apparatus comprising: a battery-operable device; and a battery cell which provides power to the battery-operable device; the battery cell comprising: a terminal; and a venting arrangement which acts to vent gas responsive to pressure buildup within the battery cell; the venting arrangement comprising a yieldable element which yields under pressure and a support which supports the yieldable element; the venting arrangement further comprising windowing disposed in the terminal, the windowing acting to vent gas to ambient; the venting arrangement further comprising a supplementary measure which forestalls collapse of the support and the yieldable element towards the terminal responsive to pressure buildup within the battery cell. 
     Furthermore, an additional aspect of the invention provides a battery cell comprising: a terminal; and a venting arrangement which acts to vent gas responsive to pressure buildup within the battery cell; the venting arrangement comprising a yieldable element which yields under pressure and a support which supports the yieldable element; the venting arrangement further comprising windowing disposed in the terminal, the windowing acting to vent gas to ambient; the venting arrangement further comprising a supplementary measure which forestalls collapse of the support and the yieldable element towards the terminal responsive to pressure buildup within the battery cell. 
     For a better understanding of the present invention, together with other and further features and advantages thereof, reference is made to the following description, taken in conjunction with the accompanying drawings, and the scope of the invention will be pointed out in the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates a computer system. 
         FIG. 2  provides cross-sectional elevational views of a conventional battery cell in different stages of action. 
         FIG. 3  provides (a) a perspective view of a spacer and (b) a cross-sectional elevational view of a battery cell employing such a spacer. 
         FIG. 4  provides a cross-sectional elevational view of a battery cell which includes edges for preventing clogging at a terminal. 
         FIG. 5  provides cross-sectional elevational views (a,c) of battery cells each employing a bursting disc with enhanced score lines and plan views in isolation (b,d) of the bursting discs themselves. 
         FIG. 6  provides (a) a cross-sectional elevational view of a battery cell with a large opening at the terminal and (b) a plan view in isolation of the terminal itself. 
         FIG. 7  provides (a,c) cross-sectional elevational views of a battery cell employing a composite bursting disc, and also in isolation (b,d) plan views of a portion of the disc itself. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For a better understanding of the present invention, together with other and further features and advantages thereof, reference is made to the following description, taken in conjunction with the accompanying drawings, and the scope of the invention will be pointed out in the appended claims. 
     It will be readily understood that the components of the present invention, as generally described and illustrated in the Figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the apparatus, system, and method of the present invention, as represented in  FIGS. 1 through 7 , is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. 
     Reference throughout this specification to “one embodiment” or “an embodiment” (or the like) means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. 
     Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention. 
     The illustrated embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals or other labels throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and processes that are consistent with the invention as claimed herein. 
     Referring now to  FIG. 1 , there is depicted a block diagram of an illustrative embodiment of a computer system  12 . The illustrative embodiment depicted in  FIG. 1  may be a notebook computer system, such as one of the ThinkPad® series of personal computers sold by Lenovo (US) Inc. of Morrisville, N.C., however, as will become apparent from the following description, the present invention is applicable to any data processing system. Notebook computers may alternatively be referred to as “notebooks”, “laptops”, “laptop computers” or “mobile computers” herein, and these terms should be understood as being essentially interchangeable with one another. It should be understood that the system  12  of  FIG. 1  provides but one illustrative and non-restrictive example among a very wide variety of systems that can be employed in accordance with embodiments of the present invention. 
     As shown in  FIG. 1 , computer system  12  includes at least one system processor  42 , which is coupled to a Read-Only Memory (ROM)  40  and a system memory  46  by a processor bus  44 . System processor  42 , which may comprise one of the AMD™ line of processors produced by AMD Corporation or a processor produced by Intel Corporation, is a general-purpose processor that executes boot code  41  stored within ROM  40  at power-on and thereafter processes data under the control of operating system and application software stored in system memory  46 . System processor  42  is coupled via processor bus  44  and host bridge  48  to Peripheral Component Interconnect (PCI) local bus  50 . 
     PCI local bus  50  supports the attachment of a number of devices, including adapters and bridges. Among these devices is network adapter  66 , which interfaces computer system  12  to a LAN, and graphics adapter  68 , which interfaces computer system  12  to display  69 . Communication on PCI local bus  50  is governed by local PCI controller  52 , which is in turn coupled to non-volatile random access memory (NVRAM)  56  via memory bus  54 . Local PCI controller  52  can be coupled to additional buses and devices via a second host bridge  60 . 
     Computer system  12  further includes Industry Standard Architecture (ISA) bus  62 , which is coupled to PCI local bus  50  by ISA bridge  64 . Coupled to ISA bus  62  is an input/output (I/O) controller  70 , which controls communication between computer system  12  and attached peripheral devices such as a keyboard and mouse. In addition, I/O controller  70  supports external communication by computer system  12  via serial and parallel ports. A disk controller  72  is in communication with a disk drive  200 . Of course, it should be appreciated that the system  12  may be built with different chip sets and a different bus structure, as well as with any other suitable substitute components, while providing comparable or analogous functions to those discussed above. 
     Generally, system  12  or essentially any suitable computer system or cell phone or other mobile device may, as is well-known, employ a battery pack that includes battery cells. Conventional cells have shown in testing that cell rupture can often be caused by a venting mechanism malfunction wherein the gasket expands and clogs the main orifices at the terminal; reference may be made again to  FIG. 2 . As shown in  FIG. 2(   a ), a conventional cell  202  may include at a positive terminal  204  thereof a number of orifices  206  which circumscribe the terminal  204  (i.e., are distributed more or less evenly about a circumferential portion of terminal  204 ) while spaced apart from terminal  204  towards an interior of cell  202  is a washer (or annular portion)  208  with a bursting disc  210  nested therewithin. As shown in  FIG. 2(   b ), normal behavior of cell  202  will desirably entail bursting disc  210  yielding or “popping up” with respect to washer  208  upon a buildup of heat or gas (and thus pressure) within cell  202  sufficient to overcome the attachment of bursting disc  210  with respect to washer  208 ; such heat and gas may thence safely vent through orifices  206 . However, as shown in  FIG. 2(   c ), such a conventional cell  202  has often been inadequate in mitigating the effects of such events, in that the venting provided by orifices  206  may not be sufficient to prevent washer  208  from collapsing towards terminal  204 ; this occurs particularly when a pressure buildup within cell  202  exceeds a specified design pressure of the cell. Worse yet, the collapsing of washer  208  towards terminal  204  has the effect of clogging up orifices  206 . 
     Normally, the bursting disc  210  will essentially be formed from the same material, or material piece, as washer  208 , wherein the bursting disc  210  is essentially delineated from the washer  208  by a circular groove that is recessed into the material of this single piece but does not fully penetrate the material. 
     The disclosure now turns to solutions, in accordance with at least one presently preferred embodiment of the present invention, that are configured to more readily accommodate greater buildups of heat or gas within a cell and thus to vent heat and gas more effectively and efficiently. Particularly, such solutions permit a cell to accommodate a pressure buildup within a cell that far exceeds a nominal design pressure of the cell, thus providing a vastly greater margin of safety than may be the case with conventional cells. Solutions are illustrated in  FIGS. 3-7 , and are provided for illustrative purposes; it should of course be understood that a very wide variety of analogous solutions may be realized in accordance with the present invention without departing from basic principles brought forth by the solutions shown in  FIGS. 3-7 . Among  FIGS. 3-7 , reference numerals indicating components similar or analogous to those shown in  FIG. 2  are increased by multiples of 100. 
       FIG. 3  provides (a) a perspective view of a spacer and (b) a cross-sectional elevational view of a battery cell employing such a spacer. As shown, spacer  312  may preferably be embodied by a ring with several orifices or holes distributed about a circumferential region thereof. This spacer ring  312  can be positioned, as shown, between washer  308  and positive terminal  304  to thereby provide a fixed gap or clearance for the bursting disc  310  to operate (popup) properly (e.g., akin to FIG.  2 [ b ]) while also serving as a “stent” or impediment which prevents washer  308  from collapsing towards positive terminal  304 , and thus prevents the above-discussed clogging of orifices  306  (e.g., akin to FIG.  2 [ c ]). 
       FIG. 4  provides a cross-sectional elevational view of a battery cell which includes edges or a lip  414  for preventing clogging at a terminal. This could thus be embodied by intermittent flanges disposed axially below (i.e., below in a direction parallel to a longitudinal axis of cell  402 ) the orifices  406 , and thusly be distributed about an imaginary circle centered on the longitudinal axis of cell  402 , or could be a continuous lip distributed about the same imaginary circle. Essentially, the effect of edges/flanges/lip  414  would be analogous to that of spacer  312  from  FIG. 3 ; washer  408  would be prevented or inhibited from collapsing upwardly while bursting disc  410  would be provided with a reliable space or clearance within which to operate. 
       FIG. 5  provides cross-sectional elevational views (a,c) of battery cells each employing a bursting disc with enhanced score lines and plan views in isolation (b,d) of the bursting discs themselves. Thus,  FIG. 5(   b ) shows in isolation a bursting disc  510   a  to be used in conjunction with cell  502   a  in  FIG. 5(   a ), while  FIG. 5(   d ) shows in isolation a bursting disc  510   b  to be used in conjunction with cell  502   b  in  FIG. 5(   c ). Essentially, the chief difference between the variant of  FIGS. 5(   a )/( b ) and that of  FIGS. 5(   c )/( d ) is that, as shown, disc  510   a  is of smaller diameter than disc  510   b . (The different bursting disc diameters help illustrate that since, in accordance with embodiments of the present invention any bursting disc or washer will be much less likely to collapse than in the case of conventional arrangements, a greater variety of diameters for the bursting disc [e.g.,  510   a/b ] are now conceivable than might otherwise be the case. In other words, inasmuch as [for instance] a large-diameter bursting disc might be more likely to lead to the clogging of venting orifices upon failure of a washer and/or bursting disc, this alone might warrant the use, in conventional arrangements, of a smaller-diameter bursting disc. In contrast, in accordance with embodiments of the present invention, it will be appreciated that the greatly reduced likelihood of bursting disc or washer failure to begin with will essentially free up the possibility of using a larger-diameter bursting disc where previously that may have been inconceivable.) 
     Otherwise, as shown, a chief feature of discs  510   a/b , respectively, is the inclusion of added score lines  514   a/b . Here, the score lines  514   a/b  (e.g., which may be embodied by small grooves or etches in the discs  510   a/b ) are embodied by a “star” pattern, where four apices of the pattern are each located at a maximum radial dimension of discs  510   a/b  and are offset from one another by 90 degrees with respect to the circumference of discs  510   a/b . As shown, extending from each of the apices are “legs” that open towards the center of each disc  510   a/b , and meet at a central region of each disc  510   a/b . The score lines  514   a/b  thus promote a more controlled and manageable yield of each disc  510   a/b  responsive to pressure buildup within the cells  502   a/b ; accordingly, by yielding “cleanly” before an extreme pressure buildup takes place, the undesirable collapse of washers  508   a/b , akin to the behavior shown in  FIG. 2(   c ), can be avoided. Other patterns than the “star” pattern illustrated can of course be borne by score lines, but a “star” pattern generally analogous to those shown in  FIG. 5  will lend itself particularly well to a “clean” yield and thus uniform distribution of pressure on a bursting disc than in the case of other scoring patterns. 
       FIG. 6  provides (a) a cross-sectional elevational view of a battery cell  602  with a large opening design at the terminal  604  and (b) a plan view in isolation of the terminal  604  itself. Here, it will be appreciated, increased venting capability is afforded at the region of terminal  604  rather than with bursting disc  610 . Particularly, terminal  604  may preferably be configured such that a nub  604   a  thereof, still sufficient for conducting battery power to a device, has extending therefrom a plurality of legs  618  that themselves terminate at an outer ring  620  of terminal  604 ; likewise, legs  618  and ring  620  are sufficiently configured to conduct battery power to a device. Accordingly, spaces  616  may remain between the legs  618  in order to permit increased venting from regions axially below terminal  604 . Thus, this will help promote a more manageable and controlled venting of heat/gas/pressure responsive to a pressure buildup within cell  602 , thereby considerably decreasing the risk of washer  608  collapsing akin to the behavior shown in  FIG. 2(   c ). Of course, essentially any workable number of legs  618  may be employed as long as structural integrity of the terminal  604  is not compromised and battery power can still be sufficiently conducted to and through nub  604   a.    
       FIG. 7  provides (a,c) cross-sectional elevational views of a battery cell  702  employing a composite bursting disc  718  in accordance with a variant embodiment of the present invention, and also in isolation (b,d) plan views a portion ( 718   a ) of the disc  718  itself. 
     Referring to  FIGS. 7(   a )/( b ), composite bursting disc  718  preferably takes the place of a combination washer and bursting disc as known conventionally and also described heretofore, and includes two portions, namely, an upper portion  718   a  which lies (e.g., is glued) atop a base portion  718   b . Upper portion  718   a  a preferably includes a segmented portion  718   c  disposed radially inward of an outer circumferential edge of upper portion  718   a . Preferably, segmented portion  718   c  is defined by scored segments (shown by the dotted lines) which meet at a central portion  718   e ; it is at least at central portion  718   a  that upper portion  718   a  is preferably bonded (e.g., glued) to base portion  718   b . Here, eight segments are shown to meet at a central portion  718   e  in the form of an octagon, but essentially any suitable number of segments and essentially any suitable shape of central portion  718   e , by way of carrying out the behavior now to be described, may be employed. 
     Essentially, base portion  718   b  may be configured as a solid disc containing perforations. Thus, the perforations would serve to transmit gas pressure towards the upper portion  718   a ; while base portion  718   b  and central portion  718   a  of upper portion  718   a  accordingly remain essentially stationary when gas is so transmitted, it will be appreciated that segments  718   d  of segmented portion  718   c  will be free to move in a manner described herebelow. 
     Preferably, including reference now to  FIGS. 7(   c )/( d ), individual segments  718   d  of segmented portion  718   c  may preferably pivot upwardly responsive to a sufficient buildup of pressure below composite bursting disc  718 . Thus, one or more segments  718   d  may yield and pivot upwardly at essentially any time when pressure buildup beneath a segment is sufficient to cause a segment to yield. An advantage is thus that composite bursting disc  718  as a whole will only have portions thereof yielding to a degree that is sufficient or necessary to accommodate a given pressure buildup within cell  702 , meaning that it need not necessarily yield in toto at such a time. At the same time, this partial yielding effect ensures that at least moderate venting can and will occur at various levels of pressure buildup within cell  702 , thus providing pressure relief as would be sufficient to prevent a larger-scale collapse of the composite disc  718  towards the terminal  704  (akin to the behavior in FIG.  2 [ c ]). 
     In addition, there may optionally be provided a barbed portion  720  that extends as shown from terminal  704  towards bursting disc  718 . This barbed portion  720  could be embodied by a complete peripheral flange extending inwardly from the terminal  704 , or it could be plural flange portions so extending. Either way, the barbed portion  720  preferably includes a pointed extension or extensions as shown, which is/are configured for “punching” along one or more score lines when pressure buildup causes composite disc  718  to displace towards barbed portion(s)  720 . Thus, this can assist in freeing segmented portions  718   d  so they can pivot upwardly as described heretofore. 
     It should be understood and appreciated that battery cells, as discussed and broadly contemplated herein, can be employed in any of a very wide variety of operating environments, including computers, cell phones, other mobile devices (such as personal digital assistants or PDA&#39;s), automobiles, and power tools (such as battery-operated power drills, saws, mowers and weed cutters). Thus, while  FIG. 1  presents a computer system by way of a possible operating environment for a battery cell in accordance with an embodiment of the present invention, it of course should be understood that this is provided by way of merely an illustrative and non-restrictive example. Battery cells, as such, can act to power a load device or other item that is configured for being battery powered. In the case of a computer, a battery cell can serve to power various components including a main memory while in the case of an automobile a battery cell can serve to power an electric motor which propels motion of the automobile. 
     If not otherwise stated herein, it is to be assumed that all patents, patent applications, patent publications and other publications (including web-based publications) mentioned and cited herein are hereby fully incorporated by reference herein as if set forth in their entirety herein. 
     Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be affected therein by one skilled in the art without departing from the scope or spirit of the invention. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims. The Abstract, as submitted herewith, shall not be construed as being limiting upon the appended claims.