Abstract:
A vehicle traction battery cell retainer includes a sidewall defining a plurality of windows each surrounded by a window flange extending therefrom, a top channel extending from the sidewall and terminating in a top flange, and a bottom channel extending from the retainer sidewall, defining a plurality of air bypass windows, and terminating in a bottom flange, the top and bottom flanges arranged for interlocking with an adjacent retainer of the traction battery. A vehicle traction battery assembly includes first and second adjacent battery cell arrays each having associated first and second retainers having a sidewall defining air flow windows and integrated top and bottom channels formed of unitary construction with interlocking flanges to couple the first and second arrays.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to devices and methods for retaining battery cells, such as the battery cells in traction batteries of hybrid or electric vehicles. 
       BACKGROUND 
       [0002]    Traction batteries, such as those in hybrid or electric vehicles, consist of interconnected battery cells. The battery cells of lower voltage are often connected to form high voltage arrays. The battery cells of the arrays may be joined together by upper and lower rails that are connected by fasteners, column ties, plates, and/or a housing. Column ties may require a substantial amount of assembly time and expense. They may not adequately withstand significant loads and may deform over time. It is desirable to have devices and methods for retaining the battery cells of an array that require less assembly time, can withstand significant loads or impact, and can prevent bowing or deformation. It is also desirable to have devices and methods for retaining the battery cells of an array that can meet certain battery requirements. 
         [0003]    The above problems and other problems are addressed by this disclosure as summarized below. 
       SUMMARY 
       [0004]    In one embodiment, a vehicle traction battery cell retainer includes a sidewall defining a plurality of windows each surrounded by a window flange extending therefrom, a top channel extending from the sidewall and terminating in a top flange, and a bottom channel extending from the retainer sidewall, defining a plurality of air bypass windows, and terminating in a bottom flange, the top and bottom flanges arranged for interlocking with an adjacent retainer of the vehicle traction battery. The retainer may include a first contoured section between the sidewall and the top flange and a second contoured section between the sidewall and the bottom flange. The first contoured section and the second contoured section may be adapted to cooperate with edges of a plurality of vehicle traction battery cells. The sidewall, top channel, and bottom channel may be formed from a single material of unitary construction, such as by stamping, for example. The plurality of windows may include windows of alternating shapes and/or sizes. 
         [0005]    In various embodiments, the retainer may include flanges having at least one tab adapted to interlock with a flange of a neighboring retainer. The retainer may also include a plurality of integrated reinforcing ribs formed between the top channel and the top flange. 
         [0006]    One embodiment of a vehicle traction battery assembly includes first and second adjacent battery cell arrays each having associated first and second retainers having a sidewall defining air flow windows and integrated top and bottom channels formed of unitary construction with interlocking flanges to couple the first and second arrays. 
         [0007]    Embodiments according to the present disclosure may provide various advantages. For example, the use of the single-piece retainer reduces the manufacturing assembly time and costs relative to previous strategies employing the use of column ties or multi-piece fasteners in assembling vehicle traction batteries. Air bypass windows within bottom channels of retainers according to various embodiments reduce temperature variation between cells in a particular array and between cells of adjacent arrays. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  depicts a representative hybrid-electric vehicle (HEV), such as a plug-in hybrid-electric vehicle (PHEV) or full hybrid-electric vehicle (FHEV) having a vehicle traction battery with retainers according to embodiments of the present disclosure; 
           [0009]      FIG. 2  is a perspective view of a vehicle traction battery assembly having a retainer according to one embodiment of the present disclosure; 
           [0010]      FIG. 3  is a perspective view of a retaining member as shown in  FIG. 2 ; and 
           [0011]      FIG. 4  is another perspective view of the vehicle traction battery assembly of  FIG. 2  showing the interlocking flanges of the retaining members. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    As required, detailed embodiments of the present disclosure are described herein; however, it is to be understood that the disclosed embodiments are merely exemplary and may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the embodiments. 
         [0013]      FIG. 1  depicts a typical hybrid-electric vehicle (HEV), such as a PHEV, for example. A hybrid-electric vehicle  12  may comprise one or more electric machines  14  mechanically connected to a transmission  16 . The electric machines  14  may be capable of operating as a motor or a generator. In addition, the hybrid transmission  16  is mechanically connected to an engine  18 . The hybrid transmission  16  is also mechanically connected to a drive shaft  20  that is mechanically connected to the wheels  22 . The electric machines  14  can provide propulsion and deceleration capability when the engine  18  is turned on or off. The electric machines  14  also act as generators and can provide fuel economy benefits by recovering energy that would normally be lost as heat in the friction braking system. The electric machines  14  may also reduce vehicle emissions by allowing the engine  18  to operate at more efficient speeds and allowing the hybrid-electric vehicle  12  to be operated in electric mode with the engine  18  off under certain conditions. 
         [0014]    A vehicle fraction battery or battery pack  24  stores energy that can be used by the electric machines  14 . A vehicle battery pack  24  typically provides a high voltage DC output. The vehicle traction battery  24  is electrically connected to one or more power electronics modules. One or more contactors (not shown) may isolate the vehicle traction battery  24  from other components when opened and connect the vehicle traction battery  24  to other components when closed. The power electronics module  26  is also electrically connected to the electric machines  14  and provides the ability to bi-directionally transfer energy between the vehicle traction battery  24  and the electric machines  14 . For example, a typical vehicle traction battery  24  may provide a DC voltage while the electric machines  14  may require a three-phase AC current to function. The power electronics module  26  may convert the DC voltage to a three-phase AC current as required by the electric machines  14 . In a regenerative mode, the power electronics module  26  may convert the three-phase AC current from the electric machines  14  acting as generators to the DC voltage required by the vehicle traction battery  24 . The description herein is equally applicable to a pure electric vehicle. For a pure electric vehicle, the hybrid transmission  16  may be a gear box connected to an electric machine  14  and the engine  18  may not be present. 
         [0015]    In addition to providing energy for propulsion, the vehicle traction battery  24  may provide energy for other vehicle electrical systems. A typical system may include a DC/DC converter module  28  that converts the high voltage DC output of the vehicle traction battery  24  to a low voltage DC supply that is compatible with other vehicle loads. Other high-voltage loads, such as compressors and electric heaters, may be connected directly to the high-voltage without the use of a DC/DC converter module  28 . The low-voltage systems may be electrically connected to an auxiliary battery  30  (e.g., 12V battery). 
         [0016]    The vehicle  12  may be any vehicle with an electrified powertrain, such as an FHEV. The vehicle  12  may also be any vehicle that includes a battery assembly made of multiple prismatic battery cells. The vehicle  12  may further be an electric vehicle, PHEV, or similar vehicle in which the vehicle traction battery  24  may be recharged by an external power source  36 . The external power source  36  may be a connection to an electrical outlet. The external power source  36  may be electrically connected to electric vehicle supply equipment (EVSE)  38 . The EVSE  38  may provide circuitry and controls to regulate and manage the transfer of energy between the power source  36  and the vehicle  12 . The external power source  36  may provide DC or AC electric power to the EVSE  38 . The EVSE  38  may have a charge connector  40  for plugging into a charge port  34  of the vehicle  12 . The charge port  34  may be any type of port configured to transfer power from the EVSE  38  to the vehicle  12 . The charge port  34  may be electrically connected to a charger or on-board power conversion module  32 . The power conversion module  32  may condition the power supplied from the EVSE  38  to provide the proper voltage and current levels to the vehicle traction battery  24 . The power conversion module  32  may interface with the EVSE  38  to coordinate the delivery of power to the vehicle  12 . The EVSE connector  40  may have pins that mate with corresponding recesses of the charge port  34 . Alternatively, various components described as being electrically connected may transfer power using a wireless inductive coupling. 
         [0017]    The various components discussed may have one or more associated controllers to control and monitor the operation of the components. The controllers may communicate via a serial bus (e.g., Controller Area Network (CAN)) or via discrete conductors. 
         [0018]      FIG. 2  and  FIG. 4  depict a vehicle traction battery, such as vehicle traction battery  24  ( FIG. 1 ) having a plurality of cells  42  arranged together to form arrays  44   a  and  44   b  that are further arranged side-to-side. The number and arrangement of the cells  42  in a particular array  44   a  or  44   b,  and the number and arrangement of arrays  44   a  and  44   b  may vary depending on the particular application and implementation. Spacers  46  are positioned between adjacent cells  42  to allow air to flow between the cells  42 . The spacers  46  also serve as insulators that aid in minimizing undesired current transmission between cells  42 . Each array includes a top surface  43  where the battery terminals are positioned, a bottom surface  45  opposite the top surface  43 , opposing ends  48  and  50 , and opposing sides  52  and  54 . Opposing ends  48  and  50  are covered by end plates  55   a  and  55   b  (shown in  FIG. 4 ), and corresponding end plates (not shown) on end  50 . Opposing sides  52  and  54  of each array  44   a  and  44   b  are substantially covered by a corresponding retaining member  56 . As such, the assembly illustrated in  FIG. 2  includes a total of four ( 4 ) retaining members  56 . 
         [0019]    Each retaining member  56  cooperates with associated top surfaces  43  and bottom surfaces  45  of the battery cells  42  of an array  44   a  or  44   b,  for example. A gusset  58  is fastened, such as by welding, to each corner of each retaining member  56  so that each retaining member  56  includes four (4) gussets  58 . A fastener  60  may be inserted through each gusset  58  to engage a corresponding threaded hole of an associated end plate  55  to secure the retaining member  56  to the end plates and thereby secure the plurality of cells  42  within the array. Several weld nuts  61  may be aligned with corresponding holes of upper flange  82  (best illustrated in  FIG. 4 ) and lower flange  76  for subsequent use in securing adjacent arrays  44   a  and  44   b  together or in securing arrays  44   a  and  44   b  to traction battery pack structures for array retention and function. A retaining member  56  is provided for and attached to each side of each array  44   a  and  44   b  such that four retaining members  56  are utilized in the representative embodiment illustrated. 
         [0020]    The retaining member  56  includes a retaining wall or sidewall  59  that defines a series of air flow windows  62   a - i  (best illustrated in  FIG. 3 ). The series of air flow windows  62   a - i  may include windows of different sizes and/or shapes arranged in any order to provide desired cooling airflow for associated battery cells  42 . In the representative embodiment illustrated, oval-shaped windows  62   a,    62   c,    62   e,    62   g,    62   i  are arranged in an alternating fashion with generally rectangular-shaped windows  62   b,    62   d,    62   f,  and  62   h.  A lower channel  70  is integrally formed of unitary construction and extends from the retaining wall  59  and defines several air bypass windows  72 . The air bypass windows  72  cooperate with the air flow windows  62   a - i  of the retaining members  56  attached to each side of the arrays  44   a  and  44   b  to provide cooling of the plurality of battery cells  42  to reduce temperature variations among the cells. The air flow windows  62   a - i  may be reconfigured or completely deleted depending on pack flow path requirements or for liquid-cooled or refrigerant-cooled traction battery packs, for example. 
         [0021]      FIG. 3  provides a close-up view a representative retaining member  56  according to one embodiment. Retaining member  56  may include various features or sections that are integrally formed in a unitary construction from a substantially homogenous material, such as sheet metal, for example. In the embodiment illustrated in  FIG. 3 , retaining member includes a retaining wall  59  that defines a series of air flow windows  62   a - i  each surrounded by an associated flange  64 . The series of air flow windows may have a design pattern, such as a repeating series of oblong-shaped window  62   a  followed by a rectangular-shaped window  62   b  and so on as previously described. The shape, orientation, and positioning of windows may vary by application to provide desired passive and/or forced air cooling of battery cells within the arrays. Windows  62   a - i  may be stamped, die cut, or otherwise formed in or from retaining wall  59 . Windows  62   a - i  may have stiffening flanges  64  surrounding them. The stiffening flanges  64  protrude from the retaining wall  59  and surround the openings of the windows  62   a - i . Stiffening flanges  64 , such as those surrounding the rectangular-shaped windows may include portions having different height or depth relative to other portions that may depend on the particular shape and arrangement of associated battery cells  42  or various application specific packaging considerations. The stiffening flanges  64  provide additional structural support to the retaining member  56  to allow it to withstand load or impact and prevent the retaining member  56  from bowing or deforming while retaining the cells during battery operation, shipping, and handling. 
         [0022]    The retaining member  56  has a first contoured section  66  extending from the top portion of the retaining wall  59  and a second contoured section  68  extending from the bottom portion of the retaining wall  59 . The first contoured section  66  and the second contoured section  68  cooperate with the edges of the battery cells and spacers to allow the retaining member  56  to integrate with the array and secure the battery cells. In certain embodiments, the first contoured section  66  and the second contoured section  68  may allow the retaining member  56  to snap fit into the array. 
         [0023]    The second contoured section  68  extends into an integrally formed channel  70  of unitary construction with contoured section  68  and retaining wall  59 . The channel  70  includes a U-shaped or C-shaped cross section with a substantially vertical portion  74  connecting a flange  76 . The substantially vertical portion  74  defines a plurality of air bypass windows  72  that cooperates with the plurality of air flow windows  62   a - i  to provide cooling of the battery cells  42  within the arrays. In one embodiment, the height of the air bypass windows is about 5 mm. Flange  76  may include one or more raised or lowered portions that may contain mounting holes  78 . The lowered portions may function as the foot, floor, or mounting surface of the vehicle traction battery. Mounting holes  78  allow the vehicle traction battery to be mounted to a surface, such as a supporting structure within a traction battery pack or a floor panel of a vehicle. 
         [0024]    As also illustrated in  FIGS. 2 and 3 , the first contoured section  66  extends to an upper side wall  80  then to a top flange  82 . Several V-shaped reinforcing ribs  84  are integrally formed of unitary construction with upper side wall  80  and top flange  82  to support the top flange  82 . The top flange  82  includes a plurality of extensions or tabs  86 , some of which may include a hole and associated weld nut as previously described. Extensions or tabs  86  are positioned or arranged to cooperate with complementary tabs or extensions formed by the top flange of a neighboring retaining member such that they would interlock and form a substantially flat and continuous surface. The extensions or tabs  86  provide additional structural support to subassemblies having multiple adjacent arrays. In certain embodiments, the extension or tabs  86  may not interlock with the top flange of a neighboring retainer member. They may nest within one another for tighter packaging. 
         [0025]    Referring to  FIG. 4 , interlocking top flanges  82  of neighboring retainer members  56  form a substantially flat and continuous surface  88 . The vehicle traction battery assembly  90  includes retainer members  56  that are attached to the sides  52 ,  54 ,  92 , and  94  of each array. In one embodiment, each of the retainer members  56  is formed from a single piece stamped material of unitary construction that has stamped or die cut windows designed to withstand load or impact and prevent bowing or deformation. The use of the single-piece retainer members  56  reduces the manufacturing assembly time and costs associated with the use of column ties or multi-piece fasteners in assembling vehicle traction batteries. 
         [0026]    Thermal analysis performed has indicated more uniform cooling of the cells and a more thermally balanced vehicle traction battery assembly that utilizes the present disclosure than existing vehicle traction batteries. The present disclosure provides devices and methods for retaining the battery cells of an array that require less assembly time, can withstand significant loads or impact, and can prevent bowing or deformation. The present disclosure further provides devices and methods for retaining the battery cells of an array that can meet certain battery transportation standards, such as Section 38.3 of the United Nations&#39; Manual of Tests and Criteria (also known as Un38.3). 
         [0027]    While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.