Abstract:
A battery thermal management system according to an exemplary aspect of the present disclosure includes, among other things, a heat spreader, a coolant channel attached to the heat spreader and a supply manifold fluidly connected with the coolant channel and configured to supply a heat transfer medium to the coolant channel. A return manifold is fluidly connected with the coolant channel and configured to expel the heat transfer medium from the coolant channel.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates to electrified vehicles, and more particularly, but not exclusively, to a battery thermal management system capable of maintaining battery cells of a battery system within a desired temperature range. 
       BACKGROUND 
       [0002]    Hybrid electric vehicles (HEV&#39;s), plug-in hybrid electric vehicles (PHEV&#39;s), battery electric vehicles (BEV&#39;s), fuel cell vehicles and other known electrified vehicles differ from conventional motor vehicles in that they are powered by one or more electric machines (i.e., electric motors and/or generators) instead of or in addition to an internal combustion engine. High voltage current for powering these types of electric machine(s) is typically supplied by a traction battery system having one or more battery cells that store energy. 
         [0003]    Battery systems are typically constructed of one or more battery modules that each includes a plurality of battery cells. In some conditions, heat is generated in the battery cells. This heat may need to be removed to improve battery cell capacity, life and performance. The battery cells may alternatively need heated in order to function properly in other conditions, such as extremely cold ambient conditions. 
       SUMMARY 
       [0004]    A battery thermal management system according to an exemplary aspect of the present disclosure includes, among other things, a heat spreader, a coolant channel attached to the heat spreader and a supply manifold fluidly connected with the coolant channel and configured to supply a heat transfer medium to the coolant channel. A return manifold is fluidly connected with the coolant channel and configured to expel the heat transfer medium from the coolant channel. 
         [0005]    In a further non-limiting embodiment of the foregoing system, the heat spreader is in contact with a battery cell. 
         [0006]    In a further non-limiting embodiment of either of the foregoing systems, the system includes a plurality of battery cells and a plurality of heat spreaders, at least one of the plurality of heat spreaders interspersed between adjacent battery cells of the plurality of battery cells. 
         [0007]    In a further non-limiting embodiment of any of the foregoing systems, the heat spreader is an annealed pyrolytic graphite plate or a flexible graphite sheet. 
         [0008]    In a further non-limiting embodiment of any of the foregoing systems, a second coolant channel is attached to an opposite edge of the heat spreader from the coolant channel. 
         [0009]    In a further non-limiting embodiment of any of the foregoing systems, a vacuum insulation panel is beneath the heat spreader. 
         [0010]    In a further non-limiting embodiment of any of the foregoing systems, a film heater is on a first side of the vacuum insulation panel and a base is on a second side of the vacuum insulation panel. 
         [0011]    In a further non-limiting embodiment of any of the foregoing systems, the heat transfer medium is a liquid coolant. 
         [0012]    In a further non-limiting embodiment of any of the foregoing systems, the coolant channel includes at least one augmentation feature. 
         [0013]    In a further non-limiting embodiment of any of the foregoing systems, a central supply line delivers the heat transfer medium to the supply manifold and a central return line communicates the heat transfer medium away from the coolant channel. 
         [0014]    A battery system according to another exemplary aspect of the present disclosure includes, among other things, a battery module having at least one battery cell and a battery thermal management system configured to heat the at least one battery cell with a film heater in response to a first temperature condition and cool the at least one battery cell by transferring heat into a heat spreader in response to a second temperature condition. 
         [0015]    In a further non-limiting embodiment of the foregoing system, the battery thermal management system includes the heat spreader adjacent to the at least one battery cell, a coolant channel attached to the heat spreader, a supply manifold near a first side of the coolant channel and a return manifold near a second side of the coolant channel. 
         [0016]    In a further non-limiting embodiment of either of the foregoing systems, the battery thermal management system include a heat exchanger configured to cool a heat transfer medium communicated through the coolant channel. 
         [0017]    In a further non-limiting embodiment of any of the foregoing systems, the battery thermal management system includes a base that supports the at least one battery cell. 
         [0018]    In a further non-limiting embodiment of any of the foregoing systems, a vacuum insulation panel is mounted to the base. 
         [0019]    In a further non-limiting embodiment of any of the foregoing systems, the film heater is positioned between the vacuum insulation panel and the at least one battery cell. 
         [0020]    A method according to another exemplary aspect of the present disclosure includes, among other things, transferring heat from a battery cell to a heat spreader, conducting the heat from the heat spreader into a coolant channel and dissipating the heat into a heat transfer medium communicated inside the coolant channel to thermally manage the battery cell. 
         [0021]    In a further non-limiting embodiment of the foregoing method, the method includes the step of sensing a temperature condition of the battery cell. 
         [0022]    In a further non-limiting embodiment of either of the foregoing methods, the method includes the step of heating the battery cell in response to the temperature condition indicating a cold ambient condition. 
         [0023]    In a further non-limiting embodiment of any of the foregoing methods, the method includes commanding the dissipating step in response to the temperature condition indicating a hot ambient condition. 
         [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 front view of a battery module of an electrified vehicle. 
           [0028]      FIG. 3  illustrates a top view of the battery module of  FIG. 2 . 
           [0029]      FIG. 4  illustrates another battery module. 
           [0030]      FIG. 5  illustrates a cooling channel of a battery thermal management system. 
           [0031]      FIG. 6  illustrates a battery thermal management system for thermally managing a battery system. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    This disclosure relates to a battery module for use in an electrified vehicle. The exemplary battery module includes a battery thermal management system capable of thermally managing one or more battery cells of the battery module. For example, the battery thermal management system described herein may be employed to heat and/or cool the battery cells in order to maintain the battery cells within a desired temperature range over a full range of ambient conditions. These and other features are described in this disclosure. 
         [0033]      FIG. 1  schematically illustrates a powertrain  10  for an electrified vehicle  12 , such as a HEV. Although depicted as a 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, PHEV&#39;s, BEV&#39;s, and fuel cell vehicles. 
         [0034]    In one embodiment, the powertrain  10  is a powersplit system that employs a first drive system that includes a combination of an engine  14  and a generator  16  (i.e., a first electric machine) and a second drive system that includes at least a motor  36  (i.e., a second electric machine), the generator  16  and a traction battery system  50 . For example, the motor  36 , the generator  16  and the traction battery system  50  may make up an electric drive system  25  of the powertrain  10 . The first and second drive systems generate torque to drive one or more sets of vehicle drive wheels  30  of the electrified vehicle  12 , as discussed in greater detail below. 
         [0035]    The engine  14 , such as an internal combustion engine, and the generator  16  may be connected through a power transfer unit  18 . In one non-limiting embodiment, the power transfer unit  18  is 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  16 . The power transfer unit  18  may include a ring gear  20 , a sun gear  22  and a carrier assembly  24 . The generator  16  is driven by the power transfer unit  18  when acting as a generator to convert kinetic energy to electrical energy. The generator  16  can alternatively function as a motor to convert electrical energy into kinetic energy, thereby outputting torque to a shaft  26  connected to the carrier assembly  24  of the power transfer unit  18 . Because the generator  16  is operatively connected to the engine  14 , the speed of the engine  14  can be controlled by the generator  16 . 
         [0036]    The ring gear  20  of the power transfer unit  18  may be connected to a shaft  28  that is connected to vehicle drive wheels  30  through a second power transfer unit  32 . The second power transfer unit  32  may include a gear set having a plurality of gears  34 A,  34 B,  34 C,  34 D,  34 E, and  34 F. Other power transfer units may also be suitable. The gears  34 A- 34 F transfer torque from the engine  14  to a differential  38  to provide traction to the vehicle drive wheels  30 . The differential  38  may include a plurality of gears that enable the transfer of torque to the vehicle drive wheels  30 . The second power transfer unit  32  is mechanically coupled to an axle  40  through the differential  38  to distribute torque to the vehicle drive wheels  30 . 
         [0037]    The motor  36  can also be employed to drive the vehicle drive wheels  30  by outputting torque to a shaft  46  that is also connected to the second power transfer unit  32 . In one embodiment, the motor  36  and the generator  16  are part of a regenerative braking system in which both the motor  36  and the generator  16  can be employed as motors to output torque. For example, the motor  36  and the generator  16  can each output electrical power to a high voltage bus  48  and the traction battery system  50 . The traction battery system  50  may be a high voltage battery that is capable of outputting electrical power to operate the motor  36  and the generator  16 . Other types of energy storage devices and/or output devices can also be incorporated for use with the electrified vehicle  12 . The traction battery system  50  may be made up of one or more battery modules that include battery cells that store the energy necessary to power the motor  36  and/or generator  16 . 
         [0038]    The motor  36 , the generator  16 , the power transfer unit  18 , and the power transfer unit  32  may generally be referred to as a transaxle  42 , or transmission, of the electrified vehicle  12 . Thus, when a driver selects a particular shift position, the transaxle  42  is appropriately controlled to provide the corresponding gear for advancing the electrified vehicle  12  by providing traction to the vehicle drive wheels  30 . 
         [0039]    The powertrain  10  may additionally include a control system  44  for monitoring and/or controlling various aspects of the electrified vehicle  12 . For example, the control system  44  may communicate with the electric drive system  25 , the power transfer units  18 ,  32  or other components to monitor and/or control the electrified vehicle  12 . The control system  44  includes electronics and/or software to perform the necessary control functions for operating the electrified vehicle  12 . In one embodiment, the control system  44  is a combination vehicle system controller and powertrain control module (VSC/PCM). Although it is shown as a single hardware device, the control system  44  may include multiple controllers in the form of multiple hardware devices, or multiple software controllers within one or more hardware devices. 
         [0040]    A controller area network (CAN)  52  allows the control system  44  to communicate with the transaxle  42 . For example, the control system  44  may receive signals from the transaxle  42  to indicate whether a transition between shift positions is occurring. The control system  44  may also communicate with a battery control module of the traction battery system  50 , or other control devices. 
         [0041]    Additionally, the electric drive system  25  may include one or more controllers  54 , such as an inverter system controller (ISC). The controller  54  is configured to control specific components within the transaxle  42 , such as the generator  16  and/or the motor  36 , such as for supporting bidirectional power flow. In one embodiment, the controller  54  is an inverter system controller combined with a variable voltage converter (ISC/VVC). 
         [0042]      FIGS. 2 and 3  illustrate an exemplary battery module  60  that can be incorporated into an electrified vehicle. For example, the battery module  60  may be employed within the battery system  50  of the electrified vehicle  12  of  FIG. 1 . The battery system  50  could include any number of battery modules  60  for supplying electrical power to the electric machines  16 ,  36  of the electrified vehicle  12  (see  FIG. 1 ). The number of battery modules  60  employed by the battery system  50  is not intended to limit this disclosure and could vary depending on the type of electrified vehicle  12 . 
         [0043]    One or more battery cells  62  may be stacked relative to one another to construct the battery module  60 . The battery cells  62  may be stacked upright, on their sides, or in any other configuration. The battery cells  62  are prismatic, lithium-ion cells, in one non-limiting embodiment. Other battery cell types may also be utilized within the scope of this disclosure. Each battery cell  62  includes two terminals  65  that project outwardly from the battery cell  62 . Cell interconnects  63  (see  FIG. 3 ) may be utilized to electrically connect adjacent battery cells  62  in parallel. The cell interconnects  63  may extend in a single plane above the battery cells  62 . In one embodiment, the parallel pairs of battery cell  62  may be connected in series with other battery cell  62  pairs. 
         [0044]    Heat may be generated by each battery cell  62  during charging and discharging operations. Heat may also be transferred into the battery cells  62  during key-off conditions of the electrified vehicle  12  as a result of relatively extreme (i.e., hot) ambient conditions. The battery module  60  may therefore include a battery thermal management system  99  for thermally managing the battery cell  62  over a full range of ambient conditions. 
         [0045]    In one embodiment, the battery thermal management system  99  includes one or more heat spreaders  64  (see  FIG. 3 ) and coolant channels  66 , a supply manifold  68  and a return manifold  70 . As discussed in greater detail below, waste heat may be transferred from the battery cells  62  to the edges of the heat spreaders  64  and subsequently dissipated via a heat transfer medium M communicated through the coolant channels  66 . 
         [0046]    The heat spreaders  64  provide heat transfer across a wrap axis  72  (see  FIG. 2 ) of the battery cells  62 . In one embodiment, one heat spreader  64  is sandwiched between two adjacent battery cells  62 . The heat spreaders  64  can be fixedly attached to the battery cells  62  in any known manner. In one embodiment, the battery module  60  includes a plurality of battery cells  62  and a plurality of heat spreaders  64 , with at least one heat spreader  64  interspersed between adjacent battery cells  62 . 
         [0047]    The heat spreaders  64  could embody any size or shape. The total number, size and shape of the battery cells  62  and the heat spreaders  64  are not intended to limit this disclosure. 
         [0048]    In one embodiment, the heat spreaders  64  are aluminum or copper sheets. In another non-limiting embodiment, the heat spreaders  64  are aluminum encapsulated annealed pyrolytic graphite plates. In another embodiment, the heat spreaders  64  are flexible graphite sheets. In yet another embodiment, the heat spreaders  64  are aluminum or steel. For example, an aluminum or steel battery casing may serve as a heat spreader. The heat spreaders  64  have a relatively high thermal conductivity in order to conduct heat out of the battery cells  62 . Other thermally conductive materials (e.g., heat pipes) may also be suitable for the heat spreaders  64 . 
         [0049]    One coolant channel  66  may be attached to each side of the heat spreader  64 . The coolant channels  66  may be connected to the heat spreader  64  in any known manner, including but not limited to, soldering, brazing, or by using thermal grease. If the battery cells  62  incorporate electrically active metal cases, the heat spreaders  64  may be electrically isolated from the battery cells  62  using, for example, thin plastic coatings. The coolant channels  66  may also extend across an entire length L of the battery module  60  (see top view of  FIG. 3 ). In other words, the coolant channels  66  define a single conduit along each side of the battery module  60 . 
         [0050]    A heat transfer medium M may be communicated through the coolant channels  66  in order to remove heat that has been conducted out of the battery cells  62  through the heat spreaders  64 . The heat transfer medium M may be a liquid coolant. In one non-limiting embodiment, the heat transfer medium M includes 60% ethylene glycol and 40% water. However, other heat transfer mediums or coolants may be suitable for this application. 
         [0051]    The heat transfer medium M is transferred to the supply manifold  68 . The supply manifold  68  communicates the heat transfer medium M to the coolant channel  66  prior to exiting through the return manifold  70 . In one embodiment, the supply manifold  68  is near a bottom  74  of the coolant channel  66  and the return manifold  70  is near a top  76  that is opposite from the bottom  74 . In the illustrated embodiment, the heat transfer medium M travels vertically from the bottom  74  toward the top  76  of the coolant channel  66  (see  FIG. 2 ). However, an opposite configuration is also contemplated in which the heat transfer medium M flows downwardly within the cooling channel  66  from the top  76  toward the bottom  74  (see  FIG. 4 ). In another embodiment, the return manifold  70  extends in a plane that is above the plane of the cell interconnects  63 . 
         [0052]    The battery cells  62  as well as the various other components of the battery module  60  are supported by a base  78 . The base  78  is a support structure that transfer loads experienced by the battery module  60  into a battery support frame (not shown). 
         [0053]    A vacuum insulation panel (VIP)  80  may be mounted to the base  78 . The VIP  80  insulates the base  78  and protects the battery cells  62  from ambient temperatures. The VIP  80  may include a relatively low thermal conductivity for thermally isolating the battery cells  62  from variations in ambient conditions. 
         [0054]    A film heater  82  may be positioned to extend between the battery cells  62  and the VIP  80 . In other words, the film heater  82  may be located at the bottom of the battery cells  62 . The film heater  82  is selectively actuated ON to heat the battery cells  62 , such as during extremely cold ambient conditions. In one embodiment, the film heater  82  is a positive-temperature-coefficient (PTC) film heater, although other heating devices are also contemplated. 
         [0055]      FIG. 5  illustrates a coolant channel  166  of a battery thermal management system  99 . 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 
         [0056]    A heat spreader  64  extends between a first battery cell  62 A and a second battery cell  62 B. The coolant channel  166  is connected to an edge  94  of the heat spreader  64 . 
         [0057]    In one embodiment, the coolant channel  166  includes at least one augmentation feature  90 . The augmentation features  90  increase the heat transfer effect between the heat transfer medium M (see  FIG. 2 ) and the cooling channel  166 . The augmentation features  90  are formed on or extend from an inner wall  92  of the coolant channel  166 . The augmentation features  90  could include a plurality of fins  96  that diagonally extend across the coolant channel  166 . However, other augmentation features having different configurations could be incorporated into the design, including but not limited to fins, turbulators, dimples or other features. 
         [0058]      FIG. 6  schematically illustrates operation of the battery thermal management system  99  as part of a closed loop system in order to thermally manage the battery cells  62  of multiple battery modules  60  of a battery system  50 . The battery thermal management system  99  may include a central supply line  102  and a central return line  104 . The central supply line  102  and the central return line  104  may extend at any location relative to the battery modules  60  of the battery system  50 . In one non-limiting embodiment, the central supply line  102  and the central return line  104  extend along a center of the battery system  50  between horizontally adjacent battery modules  60 . 
         [0059]    The central coolant supply line  102  delivers the heat transfer medium M to the supply manifolds  68  (see  FIGS. 2-3 ), which supply the coolant channels  66 . The central coolant return line  104  is in fluid communication with the return manifolds  70  (see  FIGS. 2-3 ) for expelling the heat transfer medium M from the battery system  50  after removing heat from the battery cells  62  of each battery module  60 . 
         [0060]    The heat transfer medium M may be stored within a tank  106 . A pump  108  circulates the heat transfer medium M through the closed loop battery thermal management system  99 . 
         [0061]    A heat exchanger  84  may be positioned downstream from the central return line  104 . The heat transfer medium M can therefore be communicated to the heater exchanger  84  after it has been communicated through the coolant channels  66  to remove heat from the battery cells  62 . After being cooled by the heat exchanger  84  (for example, using a separate refrigeration unit, not shown), the heat transfer medium M may be returned to the central supply line  102  to recirculate the heat transfer medium M for removing additional heat from the battery cells  62 . 
         [0062]    In one non-limiting use, the battery thermal management system  99  can heat the battery cells  62  in response to a first temperature condition TC 1  (i.e., relatively cold ambient temperatures) and cool the battery cells  62  in response to a second temperature condition TC 2  (i.e., relatively hot ambient temperatures). The first and second temperature conditions TC 1  and TC 2  can be sensed by the control system  44  (see also  FIG. 1 ), which may be in communication with the thermal management system  99 . The control system  44  may actuate the film heater  82  (shown schematically in  FIG. 6 ) ON in response to sensing the first temperature condition TC 1 . The film heater  82  heats the battery cells  62  when actuated ON. The battery cells  62  may need heated during non-operation of the electrified vehicle, such as during the winter months of colder climates. The heat transfer medium M may not be circulated through the battery thermal management system  99  in response to the first temperature condition TC 1 . 
         [0063]    The film heater  82  is commanded OFF in response to sensing the second temperature condition TC 2 . The heat exchanger  84  may be used to cool the heat transfer medium M in response to sensing the second temperature condition TC 2 . The cooled heat transfer medium M may then be returned to the central supply line  102  for cooling the battery cells  62 . Heat from the battery cells  62  is dissipated into the heat transfer medium M as it is communicated inside the coolant channels  66 . The battery cells  62  may need cooled during relatively hot ambient temperatures, such as during summer months or in warmer climates. 
         [0064]    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. 
         [0065]    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. 
         [0066]    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.