Abstract:
A battery assembly has a plurality of battery packs each presenting a housing and multiple cells adjacent one and the other and disposed in the housing. A foam solution is injected into the case of each battery pack. The foam extends around each cell and the case to encapsulate each cell thereby eliminating air gaps between the cells and the case and receiving heat generating by the cells in operational mode of the battery pack.

Description:
RELATED APPLICATIONS 
       [0001]    This non-provisional application claims priority to provisional application Ser. No. 60/797,539 filed on May 4, 2006 and 60/809,376 filed on May 30, 2006 and incorporated herewith by reference in its entirety. 
     
     FIELD OF THE INVENTION 
       [0002]    The subject invention relates to battery packs having cells and more particularly, to a battery pack for electric/hybrid vehicles having a cooling system for cooling of the cells within the battery pack. 
       BACKGROUND OF THE INVENTION 
       [0003]    Motor vehicles, such as, for example, hybrid vehicles use multiple propulsion systems to provide motive power. This most commonly refers to gasoline-electric hybrid vehicles, which use gasoline (petrol) to power internal-combustion engines (ICEs), and electric batteries to power electric motors. These hybrid vehicles recharge their batteries by capturing kinetic energy via regenerative braking. When cruising or idling, some of the output of the combustion engine is fed to a generator (merely the electric motor(s) running in generator mode), which produces electricity to charge the batteries. This contrasts with all-electric cars which use batteries charged by an external source such as the grid, or a range extending trailer. Nearly all hybrid vehicles still require gasoline as their sole fuel source though diesel and other fuels such as ethanol or plant based oils have also seen occasional use. 
         [0004]    Batteries and cells are important energy storage devices well known in the art. The batteries and cells typically comprise electrodes and an ion conducting electrolyte positioned therebetween. The art is replete with various designs of battery cell modules having retention devices are disclosed in numerous prior art references both foreign and domestic. 
         [0005]    The U.S. Pat. Nos. 4,053,691 to Ciliberti, Jr., for example, teaches a battery pack having a case, a pair of cells stacked one on top of the other and disposed in the case. A multitude of beads fills the space defined between the case and the cells. The beads are fused by an adhesive and define air gaps therebetween. The case includes vents which are used to release gas generated by the cells. Gas passes freely through the voids and around the beads to safely venting the battery pack. This design reduces the structural integrity of the battery pack and leaves air gaps between the case, which keeps heat inside the case thereby reducing product life or promoting premature failures of the battery pack. 
         [0006]    The Japanese Application No. 2003049459 to Naoki et al. teaches a battery pack having a case and a cell envelope disposed in the case. A heat absorption layer is disposed between the cell envelope and the case. The heat absorption layer is designed to absorb heat generated by the cell envelope. The design disclosed by the Japanese Application No. 2003049459 to Naoki et al. does not transfer heat beyond the case of the battery pack and keeps heat inside the case thereby reducing life span of the battery pack. 
         [0007]    The U.S. Pat. No. 4,418,127 to Shambaugh et al. teaches a battery cell module having a case including a cover, spacers, and cells disposed in the case. Before foam is applied all the surfaces must be “finished” for achieving a good bond between the materials by roughing the surfaces of the aforementioned parts to be bonded and insuring that they are thoroughly cleaned and free of any oil or other surface contaminants. After the foam has hardened, the cover is bonded over the exposed foam to form the top side of the case. The injection of the foam requires either chemically etching or sand blasting the aforementioned parts and degreasing the parts in a vapor degreaser, which is time consuming, labor intensive, and requires additional steps and materials to be used before injecting the foam. Furthermore, the U.S. Pat. No. 4,418,127 to Shambaugh et al. teaches that the cover has to be placed after the foam is hardened, thereby leaving potential air gaps which leads to a clearance defined between the foam and the cover. 
         [0008]    The Japanese Patent Application No. JP2002373708 assigned to Hitachi Koki teaches a battery pack having a plurality of cylindrical cells disposed therein and a heat receiving part of a flat heat pipe connected to the cells and is thermally coupled to a heat radiating fin mounted on the outside of a battery case. The fin does not present direct contact with the cells thereby reducing heat isolating characteristics of the battery pack taught by the Japanese Patent Application No. JP2002373708. 
         [0009]    As such, there is a constant need in the area of the battery art for an improved design of a battery pack having effective packaging characteristics, structural integrity thereby eliminating problems associated with current designs of prior art battery packs. 
       SUMMARY OF THE INVENTION 
       [0010]    A battery assembly of the present invention is adaptable to be utilized in various configurations including and not limited to an overlapping battery cell packaging configuration and a vertical stack battery cell packaging configuration used in an automotive vehicle. The battery assembly has a plurality of battery packs each presenting a case and multiple cell adjacent one and the other and disposed in the case. Each cell has a first current collector and a first electrode adjacent the first current collector and a second current collector and a second electrode of charge opposite from the first electrode and adjacent the second current collector. A separator layer is positioned between the first and second electrodes with the first and second electrodes conducting electrolyte therebetween. A foam solution is injected into the case of each battery pack. The foam extends around the perimeter of each cell&#39;s sealed edges and the case to encapsulate each cell thereby eliminating air gaps between the cells and the case. 
         [0011]    In another aspect of the present invention, a plurality of fins are formed from a heat absorption material and are disposed between the cells and extend through and beyond the case for absorbing heat generated by the cells and transferring heat beyond the case thereby maintaining a lower temperature inside each battery pack and the battery assembly. A foam solution is injected into the case of each battery pack. The foam extends around the perimeter of each cell&#39;s sealed edges and the fins and the case to encapsulate each cell thereby eliminating air gaps between the cells, the fins, and the case. A fan of the battery assembly is adjacent the battery packs. The fan introduces conditioned air into the fins extending through and beyond the case thereby cooling the fins and removing heat away from the battery packs. 
         [0012]    An advantage of the present invention is to provide a battery assembly having efficient packaging characteristics which provides excellent retention that surrounds and secures cells, and consequently secures the internal electrode stack within the cell. 
         [0013]    The retention method also provides the necessary flexibility for expansion and contraction of soft cells during the charge and discharge cycles. 
         [0014]    Another advantage of the present invention is to provide a cost effective, low mass design of a battery pack which includes polyurethane foam as a retention device verses that of traditional methods of retention, such as, for example, silicone adhesives. 
         [0015]    Still another advantage of the present invention is to provide a battery pack having a chemical resistant design wherein the internal components of the battery pack are encapsulated by the polyurethane foam which greatly reduces the potential permeation of liquids into the battery pack, or leakage from inside the battery pack to the outside of the battery pack thereby preventing reduced product life or premature failures of the battery pack. 
         [0016]    Still another advantage of the present invention is to provide a battery pack design with improved heat absorption characteristics wherein insulating air gaps are eliminated which promotes the absorption of heat generated inside the pack to be transferred to the outside of the pack. 
         [0017]    Still another advantage of the present invention is to provide a battery pack that reduces manufacturing costs due to simplified assembly pattern. 
         [0018]    Still another advantage of the present invention is to provide a battery pack having a balanced air management cooling system wherein each cell of the battery pack receives a similar temperature and flow of inlet air to assist removing the undesired heat. 
         [0019]    Still another advantage of the present invention is to provide a cooling system which allows the battery pack to deliver and receive high and fast rates of current, i.e. the C-rate, without producing heat during the rapid charge or discharge pulse that may negatively impact the performance and life span of the battery pack. 
         [0020]    Still another advantage of the present invention is to provide a pack that is simple in design and has a reduced weight. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
           [0022]      FIG. 1  is a perspective view of a plurality of cells interconnected with one another and partially encapsulated by a foam to form a pack; 
           [0023]      FIG. 2  shows alternative embodiment of the pack of  FIG. 1  having extensions integral with the foam encapsulating the pack for connecting the pack to a surface such as a body of a vehicle (not shown); 
           [0024]      FIG. 3  is a cross sectional view of a mold device of the inventive method for injecting the foam into the mold device to at least partially encapsulate the cells in the mold device; 
           [0025]      FIG. 4  is a perspective view of still another alternative embodiment of the pack having a housing (only one half is shown) having a plurality of the cells disposed in the housing and the foam injected to fill voids defined between the cells and the housing, the cells being partially encapsulated wherein the cells are connected to the electrical bus assembly; 
           [0026]      FIG. 5  is a perspective and cross sectional view still another embodiment of the present invention showing a plurality of fins disposed between the cells and extending through the housing for removing heat from inside the battery pack; and 
           [0027]      FIG. 6  shows a top view of a plurality of battery packs of  FIG. 6  adjacent one another and a fan injecting cool fluid into the fins to remove heat away from the battery packs. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0028]    Referring to the Figures, wherein like numerals indicate like or corresponding parts, a battery pack or unit assembly (the assembly) of the present invention is generally shown at  10  in  FIGS. 1 through 3 . A first alternative embodiment of the present invention is generally shown at  100  in  FIG. 4 . A second alternative embodiment of the present invention is generally shown at  200  in  FIGS. 5 and 6 . The assemblies  10 ,  100 , and  200  of the present invention are adaptable to be utilized in various configurations including and not limited to an overlapping battery cell packaging configuration and a vertical stack battery cell packaging configuration used in an automotive vehicle applications. Various cells are utilized with the present inventive concept. Preferably, lithium cells (the cells or cell)  12 ,  112 ,  212  are used with the present invention. 
         [0029]    Alluding to the above, the assemblies  10 ,  100 , and  200  of the present invention includes a lithium electronic controller (the LEC), shown in phantom at  14  in  FIGS. 1 and 2 , and  114  in  FIG. 4 , are connected to each of the respective cells  12  and  112  and operably communicates with each of the cells  12 ,  112 . Those skilled in the battery art will appreciate that the high voltage battery units deliver and receive high and/or fast rates of current (C-rate). The problem is that in exchange for the high C-rate capability, the battery units produce heat during this rapid charge or discharge pulse. 
         [0030]    As illustrated in  FIGS. 1 and 2 , the assembly  10  includes a case, generally indicated at  16 , formed from a foam  18 . The case  16  may be formed from a non-polymeric material. The case  16  presents side edges  20  through  26  and a pair of opposite sides  28  and  30 , with one of the sides  28  being partially exposed, as shown in  FIGS. 1 and 2 , to define a fame  32 , without limiting the scope of the present invention. Alternatively, the case  16  completely encapsulates the cells  12 . The frame  32  is used to identify the type of the cells  12  and to reduce the weight of the assembly  10 . In one embodiment, the assembly  10  includes a connector port  34  incorporated in the case  16  for connecting the case into a terminal (not shown) for powering the application.  FIG. 1  does not illustrate assembly  10  mounting features for surface attachment, such as the body of the vehicle (not shown). 
         [0031]    Alternatively, as shown in  FIG. 2 , a plurality boss sections or extension members  40  are formed in at least two side edges  22  and  26  for connecting the assembly  10  to the surface and designed to receive respective fasteners (not shown) extending from the surface to secure the assembly  10  thereto. The boss sections  40  may be formed from another material to provide without limiting the scope of the present invention. 
         [0032]    As illustrated in  FIG. 3  as the assembly  10  is formed, the individual cells  12  are connected to electric components, and placed in to a mold device  44  having a first mold  46  and a second mold  48  defining a cavity  50 , wherein the cells  12  are placed. The polyurethane foam solution (the foam  18 ) is injected through a nozzle  52  into the cavity  50  to secure the cells  12  and associated electrical components (not shown) within the assembly  10 . The mold device  44  is adjusted to increase the width and the heights of the assembly  10  to be formed. The mold presents a closure having at least one opening to inject the foam  18 . The mold device  44  may include a multitude of cavities (not shown) to form as many assemblies  10  as required by manufacturer. 
         [0033]    Alluding to the above, the foam  18  is injected into the mold device  44  through openings  54  defined therein. A delayed chemical reaction between the two parts of the urethane that creates an out-gassing of carbon dioxide that causes the mix to expand as a “closed cell foam”, and thus filling any voids formed between the cells  12 . The abundance of surface area contact and excellent adhesion properties of the foam  18  to the internal components provides a significant mechanical advantage of retention verses traditional methods such as RTV. The expansion of the foam  18  also greatly enhances the structural integrity of the assembly  10  with respect to shock, vibration, and crush loads. Heat transfer coefficients are improved due to the elimination of associated insulation layers created by dead air gaps. The foam  18  is a two-part polyurethane, available in densities down to less that 1 lb/ft 3 . The foam  18  occupies less than 5% of the entire pack volume inside the case  16 . The foam  18  may also occupy more than 5% of the entire pack volume inside the case  16  without limiting the scope of the present invention. 
         [0034]    Referring to  FIG. 4 , the assembly  100  includes a housing generally indicated at  102  having a pair of halves, only one is shown at  104 . A pair of extensions  106  may extend from the housing  102  for connecting the housing to the surface  36 . The housing  102  defines an internal pocket portion, generally indicated at  108  to receive the cells  112  and electronic control components  116  connected thereto. The housing  102  is fabricated from a polymeric material. Alternatively, the housing  102  is formed from a non-polymeric material without limiting the scope of the present invention. As the assembly  100  is formed, the individual cells  112  connected to the electric components  116  are placed in to the pocket  108 . The foam  18  is used to secure the cells  112  and associated electrical components  116  within the housing  102 . 
         [0035]    Preferably, the housing  102  includes opening (not shown) to receive the laminar flow of a mixed two-part polyurethane poured into the pocket portion  106  after the cells  112  and the electrical components  116  and the like, are placed into the assembled housing  102 . A delayed chemical reaction between the two parts creates an out-gassing of carbon dioxide that causes the mix to expand as a “closed cell foam”, and thus filling any voids formed between the cells  112 , and the housing  102 . The abundance of surface area contact and excellent adhesion properties of the foam  18  to the internal components provides a significant mechanical advantage of retention verses traditional methods such as RTV. The expansion of the foam  18  also greatly enhances the structural integrity of the assembly  100  with respect to shock, vibration, and crush loads. Heat transfer coefficients are improved due to the elimination of associated insulation layers created by dead air gaps. 
         [0036]    Referring to the  FIGS. 5 , the assembly  200  of the present invention a case  202  defining a pocket portion  204  to receive the cells  212  and electronic control components (not shown) connected thereto. The case  202  is fabricated from a polymeric material and includes a plurality of retention devices (not shown) integral with the case  202  and designed to receive respective fasteners (not shown) extending from a body of a vehicle to secure the assembly  200  thereto. The case  202  may be formed from a non-polymeric material. As the assembly  202  is formed, the individual cells  212  are connected to the electronic control components and placed in to the pocket  204 . 
         [0037]    A plurality of fins  214 , formed from a heat absorption material such as aluminum or the like is disposed between each cell  212 . The fins  214  extend through slits  216  defined in the case  202 . The fins  214  extend beyond the case  202 . In addition, the fins  214 , formed from the heat absorption material, such as aluminum and the like, absorb heat generated by the cells  212  and transfers heat out from the case  202  of the assembly  200 . The fins  214  are sandwiched between each cell  212  and extend beyond the case  202  thereby receiving heat from the cells  212  and sinking heat away from the case  202 . Alternatively, the fins  214  are sandwiched between the cells  212  and extend beyond the case  202  in alternating fashion, as shown in  FIG. 5 . 
         [0038]    Alluding to the above, the case  202  is molded over the cells  212  and the fins  214  disposed between the cells  212  to form the assembly  200 . The case  202  may include at least one boss section or extension (not shown) integral with and extending from the sides of the case  202  to the pocket portion  204 . The boss is designed to apply pressure to the cells  212  thereby limiting clearance between the cells  212  and the fins  214  disposed between the cells  214 . The foam  18  is used to secure the cells  212  and associated electrical components within the assembly  200 . The foam  18  is injected into the case  202  through openings (not shown) defined therein. Preferably, the openings are defined on side edges of the case  202 . A laminar flow of a mixed two-part polyurethane may be poured into the assembly  200  after the insertion of the internal components, cells  212 , the fins  214  and the like, into the case  202 . 
         [0039]    Referring to  FIG. 6 , a fan assembly  220  is adjacent several assemblies  200 . The fan assembly  220  is designed to introduce conditioned air  230  into the fins  214  of each assembly  200  extending through and beyond the respective cases  202  and for cooling the fins  214  and removing heat away from the fins  214  and the assemblies  200 . The inventive concept of the present invention provides other advantages over the prior art. One of the advantages of the present invention is to provide the assembly  10 ,  100 ,  200  having efficient packaging characteristics which provides excellent retention that surrounds and secures the cells  12 ,  112 ,  212 , secures the internal electrode stack inside the cell, circuit board assemblies, and associated electronic components regardless of their form factors in addition to component irregularities or packaging techniques. 
         [0040]    Second advantage of the present invention is unique design of the assembly  10 ,  100 ,  200  having improved adhesion and surface area contact between battery cells  12 ,  112 ,  212  and the foam  18  disposed therebetween and material density thereby providing the assembly  10 ,  100 ,  200  with the structural integrity being superior to prior art battery packs using traditional retention methods. Still another advantage of the present invention is to provide the assembly  10 ,  100 ,  200  having a chemical resistant design wherein the internal components of the assembly  10 ,  100 ,  200  are encapsulated by the polyurethane foam which greatly reduces the potential permeation of liquids into the assembly  10 ,  100 ,  200 , or leakage from inside the assembly  10 ,  100 ,  200  to the outside of the assembly  10 ,  100 ,  200  thereby preventing reduced product life or premature failures of the assembly  10 ,  100 ,  200 . 
         [0041]    Alluding to the above another advantages of the present invention are shown. The inventive battery pack design presents improved heat absorption characteristics wherein the foam retention eliminates air gaps formed between the battery cells, which promotes the absorption of heat generated inside the pack to be transferred to the outside of the assembly  10 ,  100 ,  200 . Still another advantage of the present invention is to provide the assembly  10 ,  100 ,  200  that reduces manufacturing costs due to simplified assembly pattern. 
         [0042]    Another advantages of the present invention is to provide the assembly  10 ,  100 ,  200  having efficient packaging characteristics which provides excellent retention that surrounds and secures the cells  12 ,  112 ,  212 , the internal electrode stacks within the cells  12 ,  112 ,  212 , circuit board assemblies, and associated electronic components regardless of their form factors in addition to component irregularities or packaging techniques. This retention method also provides the necessary flexibility for soft cell expansion/contraction. Still another advantage of the present invention is unique design of the assembly  10 ,  100 ,  200  having improved adhesion and surface area contact between battery cells  12 ,  112 ,  212  and the foam  18  disposed therebetween and material density thereby providing the assembly  10 ,  100 ,  200  with the structural integrity being superior to prior art battery packs using traditional retention methods. 
         [0043]    Still another advantage of the present invention is to provide the assembly  10 ,  100 ,  200  having a chemical resistant design wherein the internal components of the assembly  10 ,  100 ,  200  are encapsulated by the polyurethane foam which greatly reduces the potential permeation of liquids into the assembly  10 ,  100 ,  200 , or leakage from inside the assembly  10 ,  100 ,  200  to the outside of the assembly  10 ,  100 ,  200  thereby preventing reduced product life or premature failures of the assembly  10 ,  100 ,  200 . 
         [0044]    While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.