Abstract:
A battery pack according to an exemplary aspect of the present disclosure includes, among other things, a tray, a cover mounted to the tray and a beam system including a first beam attached to the tray and a second beam attached to the cover.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates to a battery pack for an electrified vehicle. The battery pack includes a beam system configured to structurally reinforce an enclosure of the battery pack. 
       BACKGROUND 
       [0002]    The desire to reduce automotive fuel consumption and emissions is well documented. Therefore, vehicles are being developed that reduce or completely eliminate reliance on internal combustion engines. Electrified vehicles are one type of vehicle currently being developed for this purpose. In general, electrified vehicles differ from conventional motor vehicles because 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 propel the vehicle. 
         [0003]    A high voltage battery pack typically powers the electric machines and other electrical loads of the electrified vehicle. The battery pack includes a plurality of interconnected battery cells that store energy for powering these electrical loads. The battery pack may be subjected to loading during vehicle testing, vehicle operation, or other loading events. Battery packs may therefore benefit from structural energy management. 
       SUMMARY 
       [0004]    A battery pack according to an exemplary aspect of the present disclosure includes, among other things, a tray, a cover mounted to the tray and a beam system including a first beam attached to the tray and a second beam attached to the cover. 
         [0005]    In a further non-limiting embodiment of the foregoing battery pack. the first beam and the second beam are top hat shaped. 
         [0006]    In a further non-limiting embodiment of either of the foregoing battery packs, at least one of the first beam and the second beam is movable between a first position and a second position in response to a loading event in which a force is applied to either the tray or the cover. 
         [0007]    In a further non-limiting embodiment of any of the foregoing battery packs, the first beam and the second beam abut one another in the second position. 
         [0008]    In a further non-limiting embodiment of any of the foregoing battery packs, the first beam includes a first flared portion and the second beam includes a second flared portion, and the first flared portion nests with the second flared portion. 
         [0009]    In a further non-limiting embodiment of any of the foregoing battery packs, the first flared portion is received over a protrusion of the tray. 
         [0010]    In a further non-limiting embodiment of any of the foregoing battery packs, at least one of the first beam and the second beam includes an area of varying thickness. 
         [0011]    In a further non-limiting embodiment of any of the foregoing battery packs, the first beam and the second beam are metallic structures. 
         [0012]    In a further non-limiting embodiment of any of the foregoing battery packs, at least one cutout is established between the first beam and the second beam. 
         [0013]    In a further non-limiting embodiment of any of the foregoing battery packs, a battery pack component is routed through the at least one cutout. 
         [0014]    In a further non-limiting embodiment of any of the foregoing battery packs, a second beam system is spaced from the beam system. 
         [0015]    In a further non-limiting embodiment of any of the foregoing battery packs, the first beam is attached to a bottom surface of the tray and protrudes toward the second beam, and the second beam is attached to an internal surface of the cover and protrudes toward the first beam. 
         [0016]    A battery pack according to another exemplary aspect of the present disclosure includes, among other things, an enclosure, a battery assembly housed inside the enclosure and a beam system including a first beam attached to a first portion of the enclosure and a second beam attached to a second portion of the enclosure. The first beam and the second beam are configured to abut in response to deflection of either the first portion or the second portion during a loading event. 
         [0017]    In a further non-limiting embodiment of the foregoing battery pack, the first beam and the second beam extend along a transverse axis, the transverse axis extending transverse to a longitudinal axis of the battery assembly. 
         [0018]    In a further non-limiting embodiment of either of the foregoing battery packs, the first portion of the enclosure is a tray and the second portion is a cover. 
         [0019]    In a further non-limiting embodiment of any of the foregoing battery packs, a second beam system is disposed between the first portion and the second portion of the enclosure. 
         [0020]    In a further non-limiting embodiment of any of the foregoing battery packs, the beam system is disposed between the battery assembly and an electronic module housed inside the enclosure. 
         [0021]    In a further non-limiting embodiment of any of the foregoing battery packs, the second beam is disposed at the same axial location as the first beam such that the second beam is directly above the first beam. 
         [0022]    In a further non-limiting embodiment of any of the foregoing battery packs, at least one cutout is between the first beam and the second beam. 
         [0023]    In a further non-limiting embodiment of any of the foregoing battery packs, a battery pack component is routed through the at least one cutout. 
         [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 pack of an electrified vehicle. 
           [0028]      FIG. 3  illustrates the battery pack of  FIG. 2  with the cover removed in order to better illustrate the internal components of the battery pack. 
           [0029]      FIG. 4  is a cross-sectional view through Section A-A of  FIG. 2 . 
           [0030]      FIG. 5  is another cross-sectional view of a battery pack. 
           [0031]      FIGS. 6A, 6B, 6C and 6D  schematically illustrate operation of a beam system of a battery pack during loading events. 
           [0032]      FIG. 7  illustrates another exemplary beam system for use in a battery pack. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    This disclosure details a battery pack of an electrified vehicle. The battery pack includes a beam system for structurally supporting the battery pack. In some embodiments, the beam system includes a first beam attached to a tray of a battery pack enclosure and a second beam attached to a cover of the battery pack enclosure. The first beam and the second beam are configured to abut one another in response to deflection of either the tray or the cover during a loading event. In this way, the beam system structurally reinforces the battery pack during the loading event. These and other features are discussed in greater detail in the following paragraphs of this detailed description. 
         [0034]      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. 
         [0035]    In one non-limiting 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 pack  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 depicted in  FIG. 1 , this disclosure extends to any hybrid or electric vehicle including full hybrids, parallel hybrids, series hybrids, mild hybrids or micro hybrids. 
         [0036]    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 . 
         [0037]    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 . 
         [0038]    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 . 
         [0039]    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 pack  24 . 
         [0040]    The battery pack  24  is an exemplary electrified vehicle battery. The battery pack  24  may be a high voltage traction battery pack that includes a plurality of battery assemblies  25  (i.e., battery arrays or groupings of battery cells) capable of outputting electrical power to operate the motor  22 , the generator  18  and/or other electrical loads of the electrified vehicle  12 . Other types of energy storage devices and/or output devices could also be used to electrically power the electrified vehicle  12 . 
         [0041]    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 pack  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 pack  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. 
         [0042]    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 pack  24  at a constant or approximately constant level by increasing the engine  14  propulsion. 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. 
         [0043]      FIGS. 2 and 3  illustrate a battery pack  24  that can be employed within an electrified vehicle. For example, the battery pack  24  could be part of the electrified vehicle  12  of  FIG. 1 . The battery pack  24  includes a plurality of battery cells  56  (shown schematically in  FIG. 3 ) that store electrical power for powering various electrical loads of the electrified vehicle  12 . Although a specific number of battery cells  56  are depicted in  FIG. 2 , the battery pack  24  could employ a greater or fewer number of battery cells within the scope of this disclosure. In other words, this disclosure is not limited to the specific configuration shown in  FIGS. 2 and 3 . 
         [0044]    The battery cells  56  may be stacked side-by-side along a longitudinal axis A or on top of one another to construct groupings of battery cells  56 , sometimes referred to as “cell stacks.” The battery pack  24  can include one or more separate groupings of battery cells  56 . 
         [0045]    In one non-limiting embodiment, the battery cells  56  are prismatic, lithium-ion cells. However, battery cells having other geometries (cylindrical, pouch, etc.), other chemistries (nickel-metal hydride, lead-acid, etc.), or both, could alternatively be utilized within the scope of this disclosure. 
         [0046]    The battery cells  56 , along with any other support structures (e.g., spacers, rails, walls, plates, etc.), may be collectively referred to as a battery assembly  25 . Two battery assemblies  25  are shown in  FIG. 3 ; however, the battery pack  24  could include a greater or fewer number of battery assemblies within the scope of this disclosure. 
         [0047]    An enclosure  60  generally surrounds each battery assembly  25  of the battery pack  24 . In one non-limiting embodiment, the enclosure  60  includes a tray  62  and a cover  64 . The cover  64  is shown removed in  FIG. 3  to better illustrate the interior features of the battery pack  24 . The cover  64  is attachable to the tray  62  in order to cover the battery assemblies  25 . The tray  62  and cover  64  together establish the enclosure  60 , which houses the various hardware and electronics of the battery pack  24 , including but not limited to the battery assemblies  25  and other electronic modules  58 . The battery assemblies  25  and the electronic modules  58  may be located anywhere inside the enclosure  60 . The cover  64  may be attached to the tray  62  in any known manner. In one non-limiting embodiment, the cover  64  is bolted to the tray  62 . 
         [0048]    Referring now primarily to  FIGS. 3 and 4 , the battery pack  24  additionally includes a beam system  66  for structurally reinforcing the battery pack  24 . The beam system  66  is configured to protect the internal components of the battery pack  24  during loading events. During vehicle operation or vehicle testing, for example, the battery pack  24  may be subjected to loading events in which forces are applied to the battery pack  24  along the Z-axis. During such events, the beam system  66  acts as a stiffener to absorb loads and prevent excessive deformation or deflection of either the cover  64  or the tray  62 . 
         [0049]    The beam system  66  may include a first beam  68  and a second beam  70 . The first beam  68  and the second beam  70  may be top hat shaped, in one non-limiting embodiment. The first beam  68  is attached to the tray  62  and the second beam  70  is attached to the cover  64 . The first beam  68  is attached to an inside surface of the cover  64  and protrudes toward the tray  62  (i.e., like an inverted top hat), whereas the second beam  70  is attached to a bottom surface of the tray  62  and protrudes upwardly toward the cover  64 . In one non-limiting embodiment, the first beam  68  and the second beam  70  are bolted to the tray  62  and the cover  64 , respectively. In another non-limiting embodiment, the first beam  68  and the second beam  70  are welded to the tray  62  and the cover  64 , respectively. Other attachment methodologies are also contemplated within the scope of this disclosure. 
         [0050]    The first beam  68  and the second beam  70  of the beam system  66  are metallic structures, in one non-limiting embodiment. However, the first beam  68  and the second beam  70  could be made of any material having a sufficient stiffness to absorb loads applied to either the cover  64  or the tray  62 . The first beam  68  and the second beam  70  can be stamped, machined, cast, etc. 
         [0051]    The beam system  66  is positioned at a location of the battery pack  24  that may be susceptible to excessive deformation. The actual location of the beam system  66  is therefore considered design dependent and could vary depending on the size and shape of the battery pack  14 , among other criteria. In one non-limiting embodiment, the beam system  66  extends along a transverse axis TA (e.g., from side to side in the X-axis direction). The transverse axis TA is generally transverse to the longitudinal axes A of the battery assemblies  25  (see  FIG. 3 ). In another non-limiting embodiment, the first beam  68  and the second beam  70  of the beam system  66  are each positioned at the same axial location along the Y-axis. In this way, the second beam  70  is positioned directly above the first beam  68  in the Z-axis (see  FIG. 4 ). In yet another non-limiting embodiment, the beam system  66  is disposed axially between the battery assemblies  25  and the electronic modules  58  (see  FIG. 3 ). The beam system  66  could be configured of various cross-sections or combinations of cross-sections. 
         [0052]    A single beam system  66  is depicted in  FIGS. 3 and 4 . However, the battery pack  24  could be equipped with multiple beam systems for further structurally reinforcing the battery pack  24  (see  FIG. 5 , which illustrates a battery pack  24  having a first beam system  66 A and a second beam system  66 B). It should thus be understood that the battery pack  24  could include any amount of beam systems  66  within the scope of this disclosure. 
         [0053]    In yet another non-limiting embodiment, best illustrated in  FIG. 4 , each of the first beam  68  and the second beam  70  of the beam system  66  includes a flared portion  72 . The flared portions  72  nest with one another. The flared portions  72  can optionally be provided if the tray  62  or the cover  64  includes any protrusions. One exemplary protrusion  80  of the tray  62  is illustrated in  FIGS. 3 and 4 . In such an embodiment, the flared portion  72  of the first beam  68  is received over the protrusion  80 , and the flared portion  72  of the second beam  70  is received over the flared portion  72  of the first beam  68 . 
         [0054]    One or both of the first beam  68  and the second beam  70  may include areas of varying thickness. The areas of varying thicknesses create cutouts  74 , or gaps, that extend between the first beam  68  and the second beam  70 . The first beam  68  and the second beam  70  do not contact one another at the location of the cutouts  74 , even subsequent to a loading event. Various battery pack components  82 , including but not limited to bus bar modules, sense leads, high voltage wiring, coolant lines, etc., can be routed between the first beam  68  and the second beam  70  within the cutouts  74 . During a loading event, the battery pack components  82  are not damaged by the abutting first beam  68  and second beam  70  because they are routed through the cutouts  74 . 
         [0055]      FIGS. 6A, 6B and 6C  schematically illustrate operation of the beam system  66  during a loading event. The loading event may be any event in which a force F associated with the loading event is applied to either the tray  62  or the cover  64  of the battery pack  24 . As discussed below, the first beam  68  and the second beam  70  of the beam system  66  are configured to abut one another in response to the loading event, thereby increasing the stiffness of the cover  64  and/or tray  62  to prevent excessive deformation, deflection, buckling, etc. 
         [0056]      FIG. 6A  illustrates the beam system  66  prior to application of the force F. As depicted, the first beam  68  and the second beam  70  of the beam system  66  are spaced from one another in their default positions prior to the loading event. 
         [0057]      FIG. 6B  illustrates a positioning of the beam system  66  in response to application of the force F at the cover  64 . The second beam  70  begins to move from its default position, shown in  FIG. 6A , to a second position that is closer to the first beam  68 , shown in  FIG. 6B , in response to application of the force F. 
         [0058]    Referring to  FIG. 6C , continued application of the force F at the cover  64  may cause the cover  64  to deform, deflect or buckle toward the tray  62  during the loading event. If the force F is large enough, the second beam  70  can move to a position in which it directly abuts against the first beam  68  to prevent further deformation, deflection or buckling of the cover  64 . 
         [0059]      FIG. 6D  illustrates another exemplary loading event in which the force F has been applied to the tray  62  rather than the cover  64 . If the force F is large enough, the first beam  68  can move to a position in which it abuts against the second beam  70  to prevent further deformation, deflection or buckling of the tray  62 . 
         [0060]      FIG. 7  illustrates another exemplary beam system  166 . The beam system  166  includes a first beam  168  attached to a tray  162  of a battery pack and a second beam  170  attached to a cover  164  of the battery pack. In this embodiment, the first beam  168  and the second beam  170  exclude any flared portions and are therefore substantially planar structures. However, the first beam  168  and/or the second beam  170  may include areas of varying thickness that establish cutouts  174  between the first beam  168  and the second beam  170 . The cutouts  174  accommodate various battery pack components  182  that can be routed between the first beam  168  and the second beam  170 . 
         [0061]    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. 
         [0062]    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. 
         [0063]    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.