Patent Publication Number: US-8530069-B2

Title: Battery module

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Divisional Patent Application of U.S. patent application Ser. No. 12/481,480 now U.S. Pat. No. 7,951,477, filed Jun. 9, 2009, which is a Continuation of International Patent Application No. PCT/US2007/087643, filed Dec. 14, 2007, which claims the benefit of and priority to U.S. Provisional Patent Application No. 60/874,933, filed Dec. 14, 2006, U.S. Provisional Patent Application No. 60/988,465, filed Nov. 16, 2007, and U.S. Provisional Patent Application No. 60/989,650, filed Nov. 21, 2007. 
     The disclosures of the following patent applications are incorporated by reference in their entirety: U.S. patent application Ser. No. 12/481,480 now U.S. Pat. No. 7,951,477, International Patent Application No. PCT/US2007/087643; U.S. Provisional Patent Application No. 60/874,933; U.S. Provisional Patent Application No. 60/988,465; and U.S. Provisional Patent Application No. 60/989,650. 
    
    
     BACKGROUND 
     The present application relates to battery modules or systems for use in vehicles such as hybrid electric or electric vehicles. 
     There is a need for a battery module design that provides increased resistance to damage in the event of a vehicle crash. There is also a need for a battery module that has improved cooling characteristics for the battery cells included in the module. These needs and other benefits and advantages are addressed below with regard to the various disclosed embodiments. 
     SUMMARY 
     According to one embodiment, a battery module includes a plurality of cells. The battery module also includes a housing configured to substantially enclose the plurality of cells. The battery module further includes a lower tray configured to receive the plurality of cells. The lower tray is located inside the housing adjacent a bottom of the housing and includes a top side and a bottom side. The top side has a plurality of sockets configured to receive the plurality of cells in a closely packed arrangement. The bottom side is configured to define a chamber between the lower tray and the bottom of the housing. The chamber is sealed off from the rest of the battery module and is configured to receive released gas from the plurality of cells. 
     According to another embodiment, a battery module includes a plurality of cells. The battery module also includes a housing configured to contain the plurality of cells. The battery module further includes a lower tray located inside the housing adjacent a bottom of the housing. The lower tray comprises a plurality of sockets. Each socket is configured to receive one of the plurality of cells. The battery module further includes an upper tray located inside the housing adjacent a top of the housing. The upper tray includes a plurality of sockets. Each socket is configured to receive the corresponding cell from the lower tray. The battery module further includes a common chamber defined by a bottom of the lower tray and the bottom of the housing, the common chamber configured to receive gas expelled from the plurality of cells. The battery module further includes a seal located on an upper side of the lower tray and is configured to seal the connection between the plurality of cells and the lower tray to maintain the gas in the common chamber. The battery module further includes a clamping plate located above the seal to clamp the seal between the lower tray and the clamping plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of vehicle with a battery module according to an exemplary embodiment. 
         FIG. 2  is a perspective view of a battery module according to one exemplary embodiment. 
         FIG. 3  is a perspective view of the batteries, baffles and trays from the battery module shown in  FIG. 2 . 
         FIGS. 4 and 5  are perspective views of a battery from the battery module shown in  FIG. 2 . 
         FIGS. 6 and 7  are perspective views of the battery module shown in  FIG. 2 . 
         FIG. 8  is a perspective view of the housing for the battery module shown in  FIG. 2 . 
         FIGS. 9 and 10  are perspective views of a pack from an alternative embodiment of the battery module shown in  FIG. 2 . 
         FIGS. 11 and 12  are perspective views of trays of the alternative embodiment of the battery module shown in  FIGS. 9 and 10 . 
         FIG. 13  is a perspective view of a battery module according to another exemplary embodiment. 
         FIG. 14  is a perspective partial cutaway view of the battery module shown in  FIG. 13 . 
         FIG. 15  is a perspective partial cutaway view of the battery module shown in  FIG. 13 . 
         FIG. 16  is a perspective partial cutaway view of the battery module shown in  FIG. 13 . 
         FIG. 17  is an exploded perspective view of the battery module shown in  FIG. 13 . 
         FIG. 18  is a sectional view of the battery module shown in  FIG. 13 . 
         FIG. 19  is an enlarged detail view of the battery module shown in  FIG. 18 . 
         FIG. 20  is an enlarged detail view of the battery module shown in  FIG. 18 . 
         FIG. 21  is an enlarged detail view of the battery module shown in  FIG. 18 . 
     
    
    
     DETAILED DESCRIPTION 
     For the purpose of this disclosure, the term “coupled” means the joining of two members directly or indirectly to one another. Such joining may be stationary in nature or moveable in nature. Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another. Such joining may be permanent in nature or may be removable or releasable in nature. 
     According to an exemplary embodiment, a battery module includes a plurality of electrochemical cells or batteries arranged in two groups. The batteries are arranged in trays and are surrounded by an outer housing. The trays include a plurality of sockets, sleeves or hollows configured to align and locate cells. Bus bars or connectors are used to couple the batteries together and partially by protrusions or walls on the upper tray to reduce the chance of a short circuit. The lower trays include a plurality of protrusions or standoffs and a wall that defines a volume below the cells that is configured to isolate any gases vented from the interior of the cells. Because the gasses vented from the cells may be hazardous, it is desirable to contain any vented gasses and keep them isolated from the environment. The two groups of cells are separated by a central plenum air space and a divider. The arrangement of the cells allows the module to be compressed thereby reducing damage to the cells when the module is crushed or compressed. 
     Referring to  FIG. 1 , a vehicle  10  (e.g., a hybrid-electric vehicle (HEV) or plug in HEV (PHEV)) is shown including a battery module  12  according to an exemplary embodiment. While particular exemplary embodiments of the battery module are shown and described, it should be understood that the size, shape, configuration, and/or position of the battery module may vary according to various exemplary embodiments. 
     A battery module  12  is shown according to an exemplary embodiment in  FIG. 2  and includes a housing  14 , air baffles  16 ,  18 , two battery packs  20 ,  22 , and connectors  24  conductively coupling a plurality of batteries or cells  26  in a circuit. According to an exemplary embodiment, thirty-two cells  26  are included in the battery module  12 . According to other exemplary embodiments, a different number of batteries or cells may be included in a battery module. 
     Each of the battery packs  20 ,  22  (shown, for example, in  FIGS. 9 and 10  according to an exemplary embodiment) include a plurality of batteries or cells  26  and upper and lower trays  30 ,  32 . According to an exemplary embodiment, and referring to  FIGS. 4 and 5 , the cells  26  are generally cylindrical lithium-ion cells. According to other exemplary embodiments, the batteries or cells may be another type of electrochemical cell (e.g., Nickel Metal Hydride cells, lithium polymer cells, etc.). Also, the cells may be configured in various suitable geometric configurations such as, for example, prismatic, cylindrical, polygonal, etc. 
     Referring to  FIGS. 3 ,  10 , and  11 , the bottom or lower tray  32  for the battery packs  20 ,  22  is shown. The lower tray  32  includes openings, cutouts or sockets  34  (e.g., depressions, sleeves, hollows, etc.) that receive the cells  26  in a closely packed honeycomb-like arrangement (although the cells  26  may be arranged differently according to other exemplary embodiments). The walls of the sockets  34  help locate and align the cells  26  to properly space the cells  26  and allow cooling air to pass over and/or around the cells  26 . 
     According to an exemplary embodiment, the cells  26  are arranged in two groups, banks, or packs  20 ,  22  with two rows of cells  26  in each pack  20 ,  22 . According to other exemplary embodiments, each pack may include three or four rows of batteries or cells and may be any suitable number of cells in length. The two packs  20 ,  22  are separated by a central plenum, air space or chamber  55  that may include a divider or panel  38 , as shown in  FIG. 8 . 
     According to an exemplary embodiment, the batteries or cells  26  include a venting mechanism  40  on at least one end thereof (shown as a raised portion in  FIG. 5 ) that allows the cell  26  to release internal gasses or effluent if a failure occurs to help avoid damage to the battery casing  42 . The vents  40  allow a controlled release of gasses if an internal pressure reaches a predetermined limit. 
     The cells  26  are shown to include positive and negative terminals  44  (as shown in  FIG. 4 ). Thus, the vent mechanism  40  may include a conventional pressure relief valve or other suitable valve arrangement. Terminals  44  of the cells  26  are connected by bus bars or connectors  24 . 
     As shown in  FIG. 3 , the lower tray  32  includes a wall  50  extending downward from the bottom or floor  52  of the lower tray  32  that defines a common chamber or air space  55  below the cells  26 . The lower tray  32  includes downward extending posts, protrusions or stand-offs  54  that support the floor  52  of the lower tray  32  over the chamber  55 . Wall  50  may be about 10 mm in height according to an exemplary embodiment, but may differ in other embodiments The cells  26  are suspended above the chamber on shelves or ledges extending inwardly from the walls of the sockets  34 . The cell vents  40  are in fluid communication with the chamber. In the unlikely event that a cell  26  fails, gasses released by the cell through the vent  40  will be retained in the chamber and kept generally isolated from the environment. The common air chamber may be directly or indirectly connected to outside vehicle  10 . For instance, a hole or opening in the bottom of housing  14  may fluidly connect the common air chamber of released gasses to the atmosphere (for example, through the floor of vehicle  10 ). 
     As shown in  FIG. 12 , the bottom or lower surface  60  of the upper trays  30  also includes cutouts or sockets  64  (e.g., depressions, sleeves, hollows, etc.) that receive the cells  26  in a closely packed honeycomb-like (or other type of) arrangement. Openings  66  in the upper trays  30  allow terminals  44  (seen in  FIG. 4 ) from the cell  26  to pass through the upper tray  30 . 
     Bus bars or other suitable connectors  24  are coupled to the cell terminals  44  to connect the cells  26  together to form a circuit. The bus bars  24  are received by areas defined by raised projections or walls  68  that extend upward from the top surface  62  of the upper trays. The walls  68  protect and help to isolate the bus bars  44  to reduce the chance of a bus bar  24  or terminal  44  short-circuiting with another bus bar  24  or terminal  44 . The walls  68  include slots or other openings (seen best in  FIGS. 7 and 9 ) that allow sensors  70  (e.g. voltage sensors, current sensors, temperature sensors) to be connected to the bus bars  24  or terminals  44 . These sensors  70  are connected to wires  72  that run down the length of the battery module  12  and pass through an opening  82  in the outer housing  14  (seen in the left panel in  FIG. 8 ). While sensors  70  and wires  72  are shown connecting to only a portion of the cells  26  in  FIG. 6 , according to other exemplary embodiments, sensors  70  may be provided for all the cells  26  in the battery module  12 . Temperature sensors may be located throughout the battery module  12 . An electronic control unit (ECU) may receive input from the sensors and control operation of the battery module and system accordingly. For example, the ECU may control the operation of a cooling system for the battery module  12 . For instance, the ECU may compare present values of the temperature sensors to a predetermined value and make the necessary changes to the cooling system (for example, increase, decrease, or maintain the amount of cooling). 
     According to an exemplary embodiment shown in  FIGS. 2 and 3 , the upper tray  30  for the two packs  20 ,  22  may be formed as a single unitary body and the lower tray  32  may be formed as a single unitary body. According to another exemplary embodiment, shown in  FIGS. 6-7  and  9 - 12 , the upper trays  30  and the lower trays  32  may be formed as separate bodies. A seal or gasket  36  may be provided around the circumference of the trays  30 ,  32  and around the cell sockets to isolate the common air chamber  55  for receiving vent gasses from the battery cells from the main volume of the battery module  12 . Cooling air flows through the main volume of the module and passes over the batteries or cells  26 . 
     The outer housing  14  of the battery module  12  (as shown, for example, in  FIGS. 2 and 8 ) encloses the battery packs  20 ,  22 . The outer housing  14  includes a front panel  84 , back panel  86 , left panel  88 , right panel  90 , bottom panel  92  and a top panel or cover (not shown). According to an exemplary embodiment, the housing  14  is formed from 1.5 mm thick sheet metal. The sheet metal may be painted, if desired. According to other exemplary embodiments, the housing  14  may be a polymer or other suitable material. 
     The housing  14  may include ribbing or other features suitably configured and positioned to strengthen and add rigidity to the outer housing  14 . The housing  14  includes an inlet aperture or opening  94  on the right panel  90 . The opening  94  is aligned generally with the central plenum air space and two outlet apertures or openings  96  on the left panel  88  disposed towards the front and back panels  84 ,  86 . The divider  38  may run the length of the central plenum. According to other exemplary embodiments, the two openings  96  on the left panel  88  may be inlets and the opening  94  on the right panel  90  may be an outlet. The housing  14  may also include an opening on the left, right, front, back, and/or bottom panels  84 ,  86 ,  88 ,  90  that allows vented gas to escape from the lower plenum or chamber  55 . 
     Inlet and outlet air baffles  16 ,  18  may be provided on the inside surface of the left and right panels (see, e.g.,  FIGS. 2 ,  3  and  8 ). Additionally, horizontal and vertical filler panels  98  may be provided in the housing  14 . These filler panels  98  may be located in the corners or center of the interior of the outer housing  14 . The filler panels and baffles are configured to provide relatively equal airflow within the module  12  (e.g., if there were too much space surrounding one of the cells  26  as compared to other cells  26 , undesirable low pressure zones may be formed within the module  12 ). The cells  26  in each pack  20 ,  22  are arranged in two offset rows. The air baffles  16 ,  18  are configured to maintain an air space between the cells  26  on the ends of the offset rows and the air baffles  16 ,  18  that is similar to the air space of the other rows and the walls or panels  84 ,  86 ,  88 ,  90  of the housing  14 . Cooling air passes from the opening  94 , over the cells  26  and out the openings  96  to cool the cells  26 . In an alternative embodiment, cooling air may pass from the openings  96 , over the cells  26  and out the opening  94  to cool the cells  26 . In another alternative embodiment, airflow may be bidirectional. 
     The air spaces provided in the housing  14  (and in the housing  214  discussed later) between the battery packs  20 ,  22  and the front and back panels  84 ,  86  of the housing and between the two packs  20 ,  22  allow the battery module  12  to be compressed without damaging the cells  26  (e.g., acting as crumple zones for the battery module  12  in the event of a vehicle collision). Generally, the battery module  12  would be placed in an area of the vehicle  10  that is configured to not deform in a collision (i.e. outside a “crumple zone”). But if an object or body intrudes into the space occupied by the battery module  12 , the battery module  12  is configured to be partially crushed or compressed before the cells  26  begin to be deformed. The battery module  12  is designed with internal crumple zones that allow the module  12  to be compressed, for example, up to approximately 40% in the longitudinal direction (e.g., along the length of the module  12  as shown in  FIG. 2 ) without substantially damaging the batteries or cells  26  included in the module  12 . 
     Referring to  FIGS. 13-21 , another exemplary embodiment of a battery module is shown. The embodiment shown in these figures is similar to the embodiment described above and contains many of the same features or elements, as evident from the drawings. Referring to  FIG. 17 , a battery module  212  is shown according to an exemplary embodiment. Battery module  212  is shown to include a base plate  252 , a lower tray sealing plate  250 , a lower tray  230 , a seal  238 , a seal clamping plate  228 , and multiple batteries or cells  226  (arranged in two separate battery groups or packs). Battery module  212  is also shown to include two wall plenums or external air chambers  218 , a central plenum or central air chamber  216 , and battery pack end plates  262 ,  264 . Battery module  212  is also shown to include a battery disconnect unit (BDU)  300  which includes a housing, a current sensor, a pre-charge resistor, a pre-charge relay and a contactor. Battery module  212  is also shown to include cell clamping pads  254 , upper trays  256 , bus bar assemblies  258 , a central air chamber cover  260 , cell supervising controller (CSC) boards  224 , CSC covers  222 , and a cover or housing  214 . 
     As shown in  FIG. 13 , a battery module  212  may include a housing  214 . As shown, housing  214  is made from two pieces and comprises a bottom or base plate  252  and a cover with a top, front, back, first side and second side. In an alternative embodiment, housing  214  may be made from more or less than two pieces. Openings  208  and  210  (shown in  FIGS. 13 and 17 ) are provided in housing  214  to provide an inlet and outlet for cooling air from a cooling system. In an alternative embodiment, these openings may be located elsewhere on housing  214 . Cooling air flow may enter opening  208  and exit opening  210  or cooling air may enter opening  210  and exit opening  208 . 
     Referring to  FIG. 14 , battery module  212  is shown without the cover or housing  214  and without one CSC cover  222 . Battery module  212  has two external air chambers, one for each battery pack. The external air chamber  218  is shown in  FIG. 14  to include openings  220 . These openings  220  may be generally rectangular as shown or may be any suitable shape and size. As shown, there is one opening  220  per adjacent cell  226 . In alternative embodiments, there may be more openings  220  per adjacent cell, or there may be openings  220  on less than every adjacent cell. As shown, external air chamber  218  has a taper in a first direction. This taper is to create or allow substantially constant air velocity through the battery module  212 . 
     As shown, cooling air enters the external air chamber  218  near the BDU (through opening  210  in housing  214 ) where there is no taper. Cooling air leaves external air chamber  218  through openings  220 , passing by and around cells  226  to the central air chamber  216 . The volume of cooling air decreases as cooling air advances along external air chamber  218 . The tapered shape of the chamber  218  functions to create substantially constant cooling air velocity throughout the external air chamber  218 . In an alternative embodiment, the air flow may be in a direction opposite of that described above. In yet another alternative embodiment, the external air chamber  218  may allow for bidirectional air flow. 
     Still referring to  FIGS. 15-17 , the central air chamber  216  is shown to be located between the two battery packs. As shown, the central air chamber  216  is configured to receive cooling air from the external air chambers  218  after it passes through the battery packs. Central air chamber  216  may have any number of inlets and outlets. Cooling air enters the central air chamber  216  through openings  240 . Openings  240  may be any suitable size or shape and may be located in any suitable location in central air chamber  216 . Cooling air exits the central air chamber  216  though an opening at the end of the central air chamber  216 . The central air chamber  216  is shown to include a taper in a first direction (vertical) and a second direction (horizontal). These tapers are configured to create substantially constant air flow velocity. As shown, central air chamber  216  starts out with a relatively small cross sectional area at the beginning of the central air chamber  216  and ends with a relatively large cross sectional area near the exit of the central air chamber  216 . In an alternative embodiment, cooling air may flow in a direction opposite of what was just described. For instance, cooling air may enter the large opening of the central air chamber  216  and exit through the smaller openings  240 . In another alternative embodiment, the central air chamber  216  may allow for bidirectional air flow. 
     Referring to  FIGS. 15-17 , the bottom or lower tray  230  for the batteries or cells  226  is shown. The cells are arranged into two groups or packs. The lower tray  230  includes cutouts or sockets  242  (e.g., depressions, sleeves, hollows, etc.) that receive the cells  226  in a closely packed honeycomb-like arrangement (although the cells  226  may be arranged differently according to other exemplary embodiments). The walls of the sockets  242  help locate and align the cells  226  to properly space the cells  226  and allow cooling air to pass over and/or around them. As shown in  FIGS. 15-17 , lower tray  230  is a single unitary member. In an alternative embodiment, lower tray  230  may be two separate pieces. The sockets  242  may include shelves or ledges  232  (as shown in  FIG. 21 ) on which the cells  226  may rest. Similar to battery module  12 , battery module  212  includes a common air plenum or chamber  255  between the lower tray  230  and the bottom of the housing  214 . The common air chamber is configured to receive released gasses from cells  226 . The chamber  255  is bounded on the sides by the walls  235  of the lower tray  230  and on the bottom by a tray sealing plate lower  250  and the base plate  252  of the housing  214 . 
     Referring to  FIG. 17 , the battery module  212  is shown with upper trays  256 . Upper trays  256  are similar to the upper trays  30  of battery module  12 . Upper trays  256  have a greater lead-in tolerance than lower tray  232 . As such, upper trays  256  perform less of a holding function of cells  226  than lower trays  232 . Cell clamping pads  254  may be used in combination with the upper trays to help even the clamping load or compression on the cells  226  and to reduce rattle in the battery module  212 . 
     Referring to  FIGS. 17-21 , the battery module  212  is shown to include seals  238  that are clamped between the lower tray  230  and the seal clamping plates  228 . The seals  238  positively seal in any released gasses from cells  226 . As can be seen in  FIG. 21 , seals  238  include an extension or flap  244  that presses up against the cell  226 . As pressure increases in the common air chamber, the pressure presses extension  244  against cell  226  to aid in sealing. Seal  238  also includes multiple ridges or raised portions to help positively (hermetically) seal the common air chamber from the rest of the module  212 . As discussed above, gasses in the common air chamber may be vented outside the vehicle  10  through a hole in housing  214  and vehicle  10 . 
     The cooling system for the battery module  12 ,  212  may be integrated with the cooling system for the interior of the vehicle  10  or it may be a separate cooling system. Cooling air may be connected to battery module  12 ,  212  by duct work, which may be made from, for example, sheet metal or a suitable metal of polymeric material. Cooling air may be pushed (for example, by a fan) through the battery module  12 ,  212 . Cooling air may also be pulled (for example, by a vacuum pump) through the battery module  12 ,  212 . In addition, the cooling air may flow from the central air plenum or chamber between the battery packs to the external air chamber between the battery packs and the sides or walls of the housing. Alternatively, the cooling air may flow from the external air chamber between the battery packs and the sides or walls of the housing to the central air plenum or chamber between the battery packs. The cells  26 ,  226  generally conduct heat well in the axial direction. As a result, the area of the cells covered by the walls of the sockets  34 ,  64 ,  242  does not significantly reduce the heat transfer from the cells  26 ,  226  to the cooling air. 
     It should be noted that references to “front,” “back,” “upper,” and “lower” in this description are merely used to identify various elements as are oriented in the FIGURES, with “front” and “back” being relative the vehicle in which the battery assembly is placed. 
     The construction and arrangement of the elements of the battery modules  12  as shown in the illustrated and other exemplary embodiments is illustrative only. Although only a few embodiments of the present inventions have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited herein (e.g., materials for formation of the conductive and insulating components, technology for the internal components of the cells  26 , the shape of the cells  26 , etc.). For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. It should be noted that the elements and/or assemblies of the battery module may be constructed from any of a wide variety of materials that provide sufficient strength or durability (such as aluminum, steel, copper) in any of a wide variety of colors, combinations and suitable materials. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the preferred and other exemplary embodiments without departing from the scope of the present inventions. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may be made in the design, operating configuration and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the present inventions as expressed herein.