Abstract:
A battery assembly according to an exemplary aspect of the present disclosure includes, among other things, a battery array and a foam shell that surrounds the battery array.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates to a battery assembly for an electrified vehicle. The battery assembly includes a battery array, a foam shell positioned around the battery array, and a barrier secured to the foam shell. The foam shell and barrier are configured to absorb impact energy and thermally insulate the battery array from external temperatures. 
       BACKGROUND 
       [0002]    The need to reduce automotive fuel consumption and emissions is well known. Therefore, vehicles are being developed that either reduce or completely eliminate reliance on internal combustion engines. Electrified vehicles are one type of vehicle being developed for this purpose. In general, electrified vehicles differ from conventional motor vehicles in that they are selectively driven by one or more battery powered electric machines. Conventional motor vehicles, by contrast, rely exclusively on the internal combustion engine to drive the vehicle. 
         [0003]    High voltage battery assemblies power the electric machines of an electrified vehicle. The battery assemblies typically include multiple battery arrays that include a plurality of battery cells and a support structure (i.e., end walls and sidewalls) that generally surrounds the battery cells to build the battery array. The battery arrays are typically packaged inside a sheet metal structure that includes a steel tray and a steel cover. 
       SUMMARY 
       [0004]    A battery assembly according to an exemplary aspect of the present disclosure includes, among other things, a battery array and a foam shell that surrounds the battery array. 
         [0005]    In a further non-limiting embodiment of the foregoing assembly, the foam shell is made of polypropylene or polyethylene. 
         [0006]    In a further non-limiting embodiment of either of the foregoing assemblies, a barrier is secured to the foam shell. 
         [0007]    In a further non-limiting embodiment of any of the foregoing assemblies, the barrier is made of polyamide 6, polyamide 6,6, high density polyethylene, or polypropylene. 
         [0008]    In a further non-limiting embodiment of any of the foregoing assemblies, the barrier includes a service cover that is removable from the barrier to access an electronic component of the battery assembly. 
         [0009]    In a further non-limiting embodiment of any of the foregoing assemblies, edges of the barrier are curved. 
         [0010]    In a further non-limiting embodiment of any of the foregoing assemblies, the barrier includes a plurality of straps that extend around the foam shell to secure the foam shell around the battery array. 
         [0011]    In a further non-limiting embodiment of any of the foregoing assemblies, an inner surface of the barrier includes ribbing. 
         [0012]    In a further non-limiting embodiment of any of the foregoing assemblies, the barrier includes inwardly protruding walls that establish a vent conduit around a battery cell vent. 
         [0013]    In a further non-limiting embodiment of any of the foregoing assemblies, the foam shell includes a first foam section and a second foam section nestled against the first foam section. 
         [0014]    In a further non-limiting embodiment of any of the foregoing assemblies, a foam material is provided in a space between the battery array and the foam shell. 
         [0015]    In a further non-limiting embodiment of any of the foregoing assemblies, the foam shell houses an electronic component of the battery assembly. The electronic component is housed in a different compartment of the foam shell than the battery array. 
         [0016]    In a further non-limiting embodiment of any of the foregoing assemblies, a second battery array is adjacent to the battery array. The foam shell houses both the battery array and the second battery array. 
         [0017]    In a further non-limiting embodiment of any of the foregoing assemblies, a strap extends around a barrier and the foam shell. 
         [0018]    In a further non-limiting embodiment of any of the foregoing assemblies, the strap includes a closed loop and extensions attached to the closed loop. 
         [0019]    A method according to another exemplary aspect of the present disclosure includes, among other things, housing a battery array within a foam shell and securing a barrier to the foam shell. 
         [0020]    In a further non-limiting embodiment of the foregoing method, the method includes injecting a foam material between the foam shell and the battery array. 
         [0021]    In a further non-limiting embodiment of either of the foregoing methods, the housing step includes positioning the battery array on a tray of the foam shell and nestling a cover of the foam shell against the tray. 
         [0022]    In a further non-limiting embodiment of any of the foregoing methods, the securing step includes positioning a plurality of straps of the barrier around the foam shell to secure the foam shell around the battery array. 
         [0023]    In a further non-limiting embodiment of any of the foregoing methods, the method includes positioning a strap around the barrier and the foam shell, and securing the strap to a vehicle body. 
         [0024]    The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible. 
         [0025]    The various features and advantages of this disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  schematically illustrates a powertrain of an electrified vehicle. 
           [0027]      FIG. 2  illustrates a battery assembly of an electrified vehicle. 
           [0028]      FIG. 3  illustrates a cross-sectional view of the battery assembly of  FIG. 2 . 
           [0029]      FIG. 4  illustrates a barrier of a battery assembly. 
           [0030]      FIG. 5  illustrates a cross-sectional view of a battery assembly according to another embodiment of this disclosure. 
           [0031]      FIG. 6  illustrates a battery assembly according to yet another embodiment of this disclosure. 
           [0032]      FIG. 7  illustrates a cross-sectional view of the battery assembly of  FIG. 6 . 
           [0033]      FIG. 8  illustrates a bottom perspective view of the battery assembly of  FIG. 6 . 
           [0034]      FIG. 9  illustrates strapping of a battery assembly. 
           [0035]      FIG. 10  illustrates a tray portion of a foam shell of a battery assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0036]    This disclosure details a battery assembly for an electrified vehicle. The battery assembly may include a battery array housed within a foam shell and a barrier secured to the foam shell. In some embodiments, the foam shell is a two-piece shell that includes a cover and a tray. In other embodiments, the battery assembly includes a plurality of straps to secure the assembly to a vehicle body. The exemplary battery assemblies of this disclosure employ low weight support structures that exhibit relatively high impact energy absorption and distribution and improved thermal insulation. These and other features are discussed in greater detail in the paragraphs that follow. 
         [0037]      FIG. 1  schematically illustrates a powertrain  10  for an electrified vehicle  12 . Although depicted as a hybrid electric vehicle (HEV), it should be understood that the concepts described herein are not limited to HEV&#39;s and could extend to other electrified vehicles, including, but not limited to, plug-in hybrid electric vehicles (PHEV&#39;s), battery electric vehicles (BEV&#39;s), and fuel cell vehicles. 
         [0038]    In one embodiment, the powertrain  10  is a power-split powertrain system that employs a first drive system and a second drive system. The first drive system includes a combination of an engine  14  and a generator  18  (i.e., a first electric machine). The second drive system includes at least a motor  22  (i.e., a second electric machine), the generator  18 , and a battery assembly  24 . In this example, the second drive system is considered an electric drive system of the powertrain  10 . The first and second drive systems generate torque to drive one or more sets of vehicle drive wheels  28  of the electrified vehicle  12 . Although a power-split configuration is shown, this disclosure extends to any hybrid or electric vehicle including full hybrids, parallel hybrids, series hybrids, mild hybrids or micro hybrids. 
         [0039]    The engine  14 , which in one embodiment is an internal combustion engine, and the generator  18  may be connected through a power transfer unit  30 , such as a planetary gear set. Of course, other types of power transfer units, including other gear sets and transmissions, may be used to connect the engine  14  to the generator  18 . In one non-limiting embodiment, the power transfer unit  30  is a planetary gear set that includes a ring gear  32 , a sun gear  34 , and a carrier assembly  36 . 
         [0040]    The generator  18  can be driven by the engine  14  through the power transfer unit  30  to convert kinetic energy to electrical energy. The generator  18  can alternatively function as a motor to convert electrical energy into kinetic energy, thereby outputting torque to a shaft  38  connected to the power transfer unit  30 . Because the generator  18  is operatively connected to the engine  14 , the speed of the engine  14  can be controlled by the generator  18 . 
         [0041]    The ring gear  32  of the power transfer unit  30  may be connected to a shaft  40 , which is connected to vehicle drive wheels  28  through a second power transfer unit  44 . The second power transfer unit  44  may include a gear set having a plurality of gears  46 . Other power transfer units may also be suitable. The gears  46  transfer torque from the engine  14  to a differential  48  to ultimately provide traction to the vehicle drive wheels  28 . The differential  48  may include a plurality of gears that enable the transfer of torque to the vehicle drive wheels  28 . In one embodiment, the second power transfer unit  44  is mechanically coupled to an axle  50  through the differential  48  to distribute torque to the vehicle drive wheels  28 . 
         [0042]    The motor  22  can also be employed to drive the vehicle drive wheels  28  by outputting torque to a shaft  52  that is also connected to the second power transfer unit  44 . In one embodiment, the motor  22  and the generator  18  cooperate as part of a regenerative braking system in which both the motor  22  and the generator  18  can be employed as motors to output torque. For example, the motor  22  and the generator  18  can each output electrical power to the battery assembly  24 . 
         [0043]    The battery assembly  24  is an example type of electrified vehicle battery. The battery assembly  24  may include a high voltage traction battery pack that includes a plurality of battery arrays capable of outputting electrical power to operate the motor  22  and the generator  18 . Other types of energy storage devices and/or output devices can also be used to electrically power the electrified vehicle  12 . 
         [0044]    In one non-limiting embodiment, the electrified vehicle  12  has two basic operating modes. The electrified vehicle  12  may operate in an Electric Vehicle (EV) mode where the motor  22  is used (generally without assistance from the engine  14 ) for vehicle propulsion, thereby depleting the battery assembly  24  state of charge up to its maximum allowable discharging rate under certain driving patterns/cycles. The EV mode is an example of a charge depleting mode of operation for the electrified vehicle  12 . During EV mode, the state of charge of the battery assembly  24  may increase in some circumstances, for example due to a period of regenerative braking. The engine  14  is generally OFF under a default EV mode but could be operated as necessary based on a vehicle system state or as permitted by the operator. 
         [0045]    The electrified vehicle  12  may additionally operate in a Hybrid (HEV) mode in which the engine  14  and the motor  22  are both used for vehicle propulsion. The HEV mode is an example of a charge sustaining mode of operation for the electrified vehicle  12 . During the HEV mode, the electrified vehicle  12  may reduce the motor  22  propulsion usage in order to maintain the state of charge of the battery assembly  24  at a constant or approximately constant level by increasing the engine  14  propulsion usage. The electrified vehicle  12  may be operated in other operating modes in addition to the EV and HEV modes within the scope of this disclosure. 
         [0046]      FIGS. 2 and 3  illustrate a battery assembly  54  that can be incorporated into an electrified vehicle. For example, the battery assembly  54  could be employed within the electrified vehicle  12  of  FIG. 1 . The battery assembly  54  includes a battery array  56  (see  FIG. 3 ) for supplying electrical power to the components of an electrified vehicle. Although a single battery array  56  is illustrated in  FIGS. 2 and 3 , the battery assembly  54  could include multiple battery arrays  56  within the scope of this disclosure (see, for example,  FIGS. 5 and 7 , discussed in greater detail below). In other words, this disclosure is not limited to the specific configuration shown in  FIGS. 2 and 3 . 
         [0047]    The battery array  56  includes a plurality of battery cells  58  that may be stacked side-by-side along a span length L of the battery array  56  (see  FIG. 3 ). Although not shown, the battery cells  58  may be electrically connected to one another using bus bar assemblies. In one embodiment, the battery cells  58  are prismatic, lithium-ion cells. However, other battery cells, including but not limited to nickel metal hydride or lead acid cells, could alternatively be utilized within the scope of this disclosure. 
         [0048]    The battery assembly  54  may additionally include a foam shell  60  and, optionally, a barrier  62 . The foam shell  60  and the barrier  62  are support structures of the battery assembly  54 . The foam shell  60  may be positioned around the battery array  56  to house the battery cells  58 . In one embodiment, the foam shell  60  surrounds the battery array  56  such that the battery array  56  is housed inside the foam shell  60 . The foam shell  60  may partially or entirely surround the battery array  56 . The barrier  62  may be secured to the foam shell  60  to protect any surface of the battery array  56  that is exposed or not adequately protected by the foam shell  60 . In one embodiment, the barrier  62  extends substantially along a top surface of the foam shell  60 . In other embodiments, the battery assembly  54  may completely exclude the barrier  62  (see, for example, the embodiment of  FIG. 7 ). 
         [0049]    The foam shell  60  may be made of a structural, microcellular foam material. In this disclosure, the term “foam” refers to any material containing numerous cells, intentionally introduced, interconnecting or not, distributed throughout a mass. Non-limiting examples of suitable foam materials include expanded polypropylene (EPP) or expanded polyethylene (EPE, cross-linked or uncross-linked). In one embodiment, these materials may be used in either a steam chest molding process or an injection molding process to manufacture a foam shell  60  having any desired shape. 
         [0050]    In another non-limiting embodiment, the foam shell  60  is a two-piece shell that includes a first foam section  64  and a second foam section  66 . The first foam section  64  may surround a first portion of the battery array  56 , whereas the second foam section  66  may surround a second portion of the battery array  56 . The first foam section  64  may abut the second foam section  66  to generally surround the battery array  56 . In one embodiment, the first foam section  64  is configured as a cover and the second foam section  66  is configured as a tray. The battery array  56  is positioned on top of the first foam section  64 , and the second foam section  66  is then positioned over the battery array  56 . The barrier  62  is received against the first foam section  64 , which in this embodiment is configured as a cover. 
         [0051]    The foam shell  60  may surround various additional components of the battery assembly  54  in addition to the battery array  56 . For example, as shown in  FIG. 3 , one or more electronic components  70  may be housed within the foam shell  60 . The electronic components  70  may include one or more of a battery electric control module (BECM), a bussed electrical center (BEC) and a service disconnect, among other components. In one embodiment, the battery array  56  is positioned within a first compartment  72  of the foam shell  60 , and one or more electronic components  70  are housed within a second compartment  74  of the foam shell  60  that is separate from the first compartment  72 . A wall  76  may divide the first compartment  72  from the second compartment  74 . The wall  76  is a molded-in feature of the foam shell  60  and may electrically insulate the components housed in the first compartment  72  from the components housed in the second compartment  74 . 
         [0052]    In another embodiment, portions of the battery assembly  54  may be foamed into place to fixate these components within the foam shell  60 . A foam material  78 , such as polyurethane (PU), may be injected around the electronic components  70  for fixation within the foam shell  60  once cured. Foam material  78  may also be injected into spaces  80  that extend between the battery array  56  and the foam shell  60  for increased structural support. In one embodiment, the foam material  78  may be part of a foam-in-bag packaging that is easily removable if the battery array  56  or electronic components  70  require servicing. 
         [0053]    Portions of the foam shell  60  may be contoured to match a shape of a vehicle body  68 . For example, in one non-limiting embodiment, a bottom surface  69  of the second foam section  66  includes multiple recesses  71  that receive protrusions  73  that extend upwardly from the vehicle body  68 . The vehicle body  68  is a floor pan of an electrified vehicle, in one embodiment. The battery assembly  54  can be securely positioned and mounted to the vehicle body  68  by virtue of the matching contours. 
         [0054]    The barrier  62  may be positioned over top of the foam shell  60 . The barrier  62  provides additional protection to the components housed inside the foam shell  60  against impact events or puncture events due to sharp objects contacting the battery assembly  54 . The barrier  62  may be made of a plastic material. Non-limiting examples of suitable plastic materials include polyamide 6 (PA6), polyamide 6,6 (PA6,6), high density polyethylene (HDPE), polypropylene (PP), etc. In another embodiment, two or more of plastic materials can be either co-injection molded or co-extruded into a multi-layer structure that forms the barrier  62 . In yet another embodiment, the barrier  62  can be made of a plastic material that is filled with reinforcements such as continuous or discontinuous glass or carbon fibers. In yet another embodiment, the barrier  62  includes a sheet metal that is over-molded with a plastic material. In yet another embodiment, the barrier  62  is made of metal, such as a stamped steel or cast aluminum. 
         [0055]    The barrier  62  may also include a service cover  82  that is removable from the barrier  62  to access one of the electronic components  70  of the battery assembly  54 . In one embodiment, the electronic component  70  is a service disconnect. The service cover  82  may snap into an opening  83  of the barrier  62 . The service cover  82  may be tethered to the barrier  62  to avoid displacement after it is temporarily removed. If the service cover  82  is not provided, the entire barrier  62  can be removed to access the electronic component(s)  70 . 
         [0056]    In another embodiment, a depression  85  is formed in the barrier  62  near the opening  83  (see  FIG. 2 ). The depression  85  facilitates water drainage away from the service cover  82 , and therefore away from the components housed underneath the service cover  82 . Edges  84  of the barrier  62  may be curved to facilitate water drainage away from the battery assembly  54 . The edges  84  ensure that water does not pool atop the barrier  62 . 
         [0057]    Referring now to  FIGS. 2, 3 and 4 , retention legs  86  may protrude downwardly from each corner  88  of the barrier  62 . The retention legs  86  may be molded-in features for retaining the battery assembly  54  to the vehicle body  68 . In one non-limiting embodiment, the battery assembly  54  can be bolted to the vehicle body  68  via openings  87  in the retention legs  86 . The openings  87  may include reinforcements over molded or inserted into the retention legs  86 . 
         [0058]    The barrier  62  may further include an outer surface  90  and an inner surface  92 . The inner surface  92  may include ribbing  94  that reinforces the barrier  62  (see  FIG. 4 ). In one embodiment, the ribbing  94  is honeycomb shaped. The ribbing  94  of the inner surface  92  may nestle into honeycomb-shaped depressions on top of the foam shell  64  to resist movement between the barrier  62  and the foam shell  60 . 
         [0059]    In another embodiment, the barrier  62  includes a plurality of straps  96  that extend from opposing sides  95 ,  97  of the barrier  62 . The plurality of straps  96  may extend around the foam shell  60  to secure the first foam section  64  and the second foam section  66  around the battery array  56 . The straps  96 A of the side  95  may be fastened to the straps  96 B of the side  97  (see, for example,  FIG. 4 ). The straps  96 A,  96 B can be tied together using fasteners, clips, welding, adhesives, etc. 
         [0060]      FIG. 5  illustrates another exemplary battery assembly  154 . In this disclosure, like reference numbers designate like elements where appropriate and reference numerals with the addition of 100 or multiples thereof designate modified elements that are understood to incorporate the same features and benefits of the corresponding original elements. 
         [0061]    In this embodiment, the battery assembly  154  includes a first battery array  156 A and a second battery array  156 B that are surrounded by a foam shell  160 . A barrier  162  is attached to the foam shell  160 . Each battery array  156 A,  156 B includes battery cells  158 . The battery cells  158  include cell vents  159  that may expel vent gases G during some conditions. The cell vents  159  may be uncovered by the foam shell  160 . The bather  162  may include walls  163  that extend inwardly from an inner surface  192 . The walls  163  may extend into openings  165  of the foam shell  160 . The openings  165  extend around the cell vents  159 . The walls  163  establish vent conduits  167  that direct the vent gases G to a desired location outside of an electrified vehicle during battery cell  158  venting events. 
         [0062]      FIGS. 6, 7 and 8  illustrate yet another exemplary battery assembly  254 . The battery assembly  254  may include a foam shell  260  and a bather  262  connected to the foam shell  260 . Battery arrays  256  are housed inside the foam shell  260  (see  FIG. 7 ). 
         [0063]    The battery assembly  254  may be secured to a vehicle body  268  (shown in  FIG. 6 ) using one or more straps  298 . In one non-limiting embodiment, the straps  298  are made of woven nylon webbing, such as used in seatbelts. However, other materials are also contemplated, including but not limited to, continuous glass fiber tape, etc. 
         [0064]    The straps  298  may be looped around the barrier  262  and the foam shell  260  and then secured to the vehicle body  268  using metal clips  299  to substantially prevent lateral movement of the battery assembly  254 . In one embodiment, the straps  298  extend across an outer surface  290  of the barrier  262 , extend along sides  281  of the foam shell  260 , and extend within grooves  275  formed in a bottom surface  269  of the foam shell  260  (see  FIGS. 6 and 8 ). The metal clips  299  are attached to the straps  298  and may be anchored to the vehicle body  268  with fasteners  277  on both sides of the battery assembly  254 . 
         [0065]    Referring primarily to  FIG. 7 , the foam shell  260  may include a cover  264  and a tray  266  that nestle together to surround the battery arrays  256 . In one embodiment, the cover  264  and the tray  266  are glued together to secure the foam shell  260  around the battery arrays  256 . The barrier  262  is removed in  FIG. 7  to better illustrate the foam shell  260 . In another embodiment, a heat exchanger  279 , such as a cold plate, is positioned between the battery arrays  256  and the tray  266 . The heat exchanger  279  functions to remove heat generated by the battery arrays  256  during certain conditions, or alternatively to heat the battery arrays  256  during other conditions. 
         [0066]      FIG. 9  illustrates an exemplary strap  298  that can be used to secure the battery assembly  254  to the vehicle body  268  (such as shown in  FIG. 7 ). The strap  298  may include a closed loop  201  and extensions  203  that are attached to the closed loop  201 . In one embodiment, the extensions  203  are sewn to the closed loop  201 . The extensions  203  may be attached to the closed loop  201  at locations that are inboard of edges  205  of the closed loop  201 . The extensions  203  include sleeves  207  that can receive metal clips  299 . 
         [0067]      FIG. 10  illustrates an exemplary tray  266  of the foam shell  260 . The tray  266  may include a plurality of molded-in walls  209 . The walls  209  establish a plurality of compartments  272  inside the tray  266 . Different components of the battery assembly  254 , including the battery arrays  256  and electronic components  270 , may be positioned within the compartments  272 . The walls  209  act as energy absorbing barriers to protect these components. In some embodiments, the tray  266  (and the cover  264  of  FIG. 7 ) can include channels formed through the molded-in walls  209  for the inclusion of cooling and electrical lines between the compartments  272 . 
         [0068]    Although the different non-limiting embodiments are illustrated as having specific components or steps, the embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments. 
         [0069]    It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should be understood that although a particular component arrangement is disclosed and illustrated in these exemplary embodiments, other arrangements could also benefit from the teachings of this disclosure. 
         [0070]    The foregoing description shall be interpreted as illustrative and not in any limiting sense. A worker of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure. For these reasons, the following claims should be studied to determine the true scope and content of this disclosure.