Patent Publication Number: US-2018048038-A1

Title: Thermal exchange plate assembly for vehicle battery

Description:
BACKGROUND 
     This disclosure relates to a battery assembly for an electrified vehicle. The battery assembly has a thermal exchange plate assembly, which includes a wire mesh structure. 
     The need to reduce automotive fuel consumption and emissions is well known. Therefore, vehicles are being developed that 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 because they are selectively driven by battery powered electric machines. Conventional motor vehicles, by contrast, rely exclusively on the internal combustion engine to propel the vehicle. 
     High voltage battery assemblies are employed to power the electric machines of electrified vehicles. The battery assemblies include battery arrays constructed of a plurality of battery cells. An enclosure assembly houses the battery arrays. A cold plate may be placed in contact with the battery cells to thermally manage the heat generated by the battery cells. 
     SUMMARY 
     A battery assembly according to an exemplary aspect of the present disclosure includes, among other things, a plurality of battery cells and a thermal exchange plate assembly in contact with the plurality of battery cells. The thermal exchange plate assembly includes a wire mesh structure. 
     In a further non-limiting embodiment of the foregoing battery assembly, the wire mesh structure includes a first set of parallel wires spaced-apart from one another and a second set of parallel wires spaced-apart from one another. The first and second sets of wires are interwoven. 
     In a further non-limiting embodiment of any of the foregoing battery assemblies, the first and second sets of wires are metallic wires. 
     In a further non-limiting embodiment of any of the foregoing battery assemblies, the thermal exchange plate assembly further includes a first facesheet on a first side of the wire mesh structure and a second facesheet on a second side of the wire mesh structure opposite the first side. 
     In a further non-limiting embodiment of any of the foregoing battery assemblies, the first and second sets of wires are interwoven such that the wire mesh structure has a square orientation when viewed in a direction parallel to a plane of the first facesheet. 
     In a further non-limiting embodiment of any of the foregoing battery assemblies, the wire mesh structure is arranged such that each wire in the first set of wires has a respective longitudinal axes extending substantially perpendicular to a plane defined by the first facesheet, and such that each wire in the second set of wires has a respective longitudinal axis extending substantially parallel to the plane. 
     In a further non-limiting embodiment of any of the foregoing battery assemblies, the first and second sets of wires are interwoven such that the wire mesh structure has a square orientation when viewed in a direction perpendicular to a plane of the first facesheet. 
     In a further non-limiting embodiment of any of the foregoing battery assemblies, the wire mesh structure is oriented such that each wire in the first set of wires has a respective longitudinal axis extending substantially parallel to a plane defined by the first facesheet, and such that each wire in the second set of wires has a respective longitudinal axis extending both substantially parallel to the plane and substantially perpendicular to the longitudinal axes of the first set of wires. 
     In a further non-limiting embodiment of any of the foregoing battery assemblies, the first and second sets of wires are interwoven such that the wire mesh structure has a diamond orientation when viewed in a direction parallel to a plane of the first facesheet. 
     In a further non-limiting embodiment of any of the foregoing battery assemblies, the wire mesh structure is oriented such that each wire in the first set of wires has a respective longitudinal axis extending at a first acute angle relative to a plane defined by the first facesheet, and such that each wire in the second set of wires has a respective longitudinal axis extending at a second acute angle relative to the plane. 
     In a further non-limiting embodiment of any of the foregoing battery assemblies, the second acute angle is provided by reflecting the first acute angle about an axis perpendicular to the plane. 
     In a further non-limiting embodiment of any of the foregoing battery assemblies, a fluid flow path is provided between the first and second facesheets. 
     In a further non-limiting embodiment of any of the foregoing battery assemblies, the thermal exchange plate assembly includes a fluid inlet and a fluid outlet. The fluid inlet and the fluid outlet are fluidly coupled to the fluid flow path. 
     In a further non-limiting embodiment of any of the foregoing battery assemblies, the battery assembly further includes a housing enclosing the plurality of battery cells. The housing encloses the fluid flow path on a first side and a second side opposite the first side. 
     In a further non-limiting embodiment of any of the foregoing battery assemblies, the thermal exchange plate assembly is in contact with the plurality of battery cells by way of an intermediate thermally insulating material. 
     An assembly according to an exemplary aspect of the present disclosure includes, among other things, a first facesheet, a second facesheet, and a wire mesh structure provided between the first facesheet and the second facesheet. 
     In a further non-limiting embodiment of the foregoing assembly, the wire mesh structure includes a first set of parallel wires spaced-apart from one another and a second set of parallel wires spaced-apart from one another. The first and second sets of wires are interwoven. 
     In a further non-limiting embodiment of any of the foregoing assemblies, the first and second sets of wires are metallic wires. 
     A method of forming an assembly according to an exemplary aspect of the present disclosure includes, among other things, bonding a facesheet to a wire mesh structure. 
     In a further non-limiting embodiment of the foregoing assembly, the facesheet is bonded to the wire mesh structure using transient liquid phase (TLP) brazing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates an example electrified vehicle. 
         FIG. 2  schematically illustrates an example battery assembly. 
         FIG. 3  illustrates an example thermal exchange plate assembly. 
         FIG. 4A  illustrates a first aspect of an example method of forming a thermal exchange plate assembly. 
         FIG. 4B  illustrates a second aspect of the example method of forming the thermal exchange plate assembly. 
         FIG. 5A  illustrates is a front view of a first orientation of a wire mesh structure of the thermal exchange plate assembly. In  FIG. 5A , the wire mesh structure is provided in a diamond orientation. 
         FIG. 5B  is a cross-sectional view taken along line  5 B- 5 B from  FIG. 5A . 
         FIG. 6A  illustrates is a front view of a second orientation of a wire mesh structure of the thermal exchange plate assembly. In  FIG. 6A , the wire mesh structure is provided in a first square orientation. 
         FIG. 6B  is a cross-sectional view taken along line  6 B- 6 B from  FIG. 6A . 
         FIG. 7A  illustrates is a front view of a third orientation of a wire mesh structure of the thermal exchange plate assembly. In  FIG. 7A , the wire mesh structure is provided in a second square orientation. 
         FIG. 7B  is a cross-sectional view taken along line  7 B- 7 B from  FIG. 7A . 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure relates to an assembly for an electrified vehicle. The assembly may be a battery assembly that includes a thermal exchange plate assembly for thermally managing heat generated by battery cells of the battery assembly. In one example, the thermal exchange plate assembly includes a wire mesh structure, which provides an increased surface area for heat transfer, and also distributes heat further away from the battery cells. These and other features are discussed in greater detail in the following paragraphs of this detailed description. 
       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) and battery electric vehicles (BEV&#39;s). 
     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. 
     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 . 
     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 . 
     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 . 
     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 . 
     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, or groupings of battery cells, 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 . 
     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. 
     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. 
       FIG. 2  illustrates 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 battery arrays  56 , which can be described as groupings of battery cells, for supplying electrical power to various vehicle components. Although two battery arrays  56  are illustrated in  FIG. 2 , the battery assembly  54  could include a single battery array or multiple battery arrays within the scope of this disclosure. In other words, this disclosure is not limited to the specific configuration shown in  FIG. 2 . 
     Each battery array  56  includes a plurality of battery cells  58  that may be stacked side-by-side along a span length of each battery array  56 . Although not shown in the highly schematic depiction of  FIG. 2 , the battery cells  58  are electrically connected to one another using busbar assemblies. In one embodiment, the battery cells  58  are prismatic, lithium-ion cells. However, battery cells having other geometries (cylindrical, pouch, etc.) and/or other chemistries (nickel-metal hydride, lead-acid, etc.) could alternatively be utilized within the scope of this disclosure. 
     An enclosure assembly  60  (shown in phantom in  FIG. 2 ) surrounds the battery arrays  56 . The enclosure assembly  60  defines an interior  66  for housing the battery arrays  56  and, potentially, any other components of the battery assembly  54 . In one non-limiting embodiment, the enclosure assembly  60  includes a tray  62  and a cover  64  which establish a plurality of walls  65  that surround the interior  66 . The enclosure assembly  60  may take any size, shape or configuration, and is not limited to the specific configuration of  FIG. 2 . 
     During some conditions, heat may be generated by the battery cells  58  of the battery arrays  56  during charging and discharging operations. Heat may also be transferred into the battery cells  58  during vehicle key-off conditions as a result of relatively hot ambient conditions. During other conditions, such as relatively cold ambient conditions, the battery cells  58  may need heated. A thermal management system  75  may therefore be utilized to thermally condition (i.e., heat or cool) the battery cells  58 . 
     The thermal management system  75 , for example, may include a fluid source  77 , an inlet  79 , an outlet  81 , and a thermal exchange plate assembly  70 . The thermal exchange plate assembly  70  may, in some examples, be referred to as a cold plate assembly. In one embodiment, the inlet  79  and the outlet  81  fluidly couple the fluid source  77  to the thermal exchange plate assembly  70  and may include tubes, hoses, pipes or the like. A fluid F, such as glycol or some other suitable fluid, is communicated from the fluid source  77  to the inlet  79 , through tubing  72  of the thermal exchange plate assembly  70 , and then through the thermal exchange plate assembly  70 . The fluid F is circulated through the thermal exchange plate assembly  70 , which is in contact with one or more surfaces of the battery cells  58 , to either add or remove heat to/from the battery assembly  54 . In other words, the fluid F may enhance the heat transfer effect achieved by the thermal exchange plate assembly  70 . The fluid F may then be discharged through the tubing  72  into the outlet  81  before returning to the fluid source  77 . 
     In one example, there are two arrays of battery cells  58 . In that example, the fluid F may flow from the fluid source  77 , through a portion of the thermal exchange plate assembly  70  corresponding a first array, and then flow in series to the portion of the thermal exchange plate assembly  70  corresponding to the second array before returning to the outlet  81 . In another example, the fluid flows from the inlet  79  and flows in parallel through the portions of the thermal exchange plate assembly  70  corresponding to the first and second arrays before returning to the outlet  81 . 
     Because the fluid F can either take on heat from the battery cells  58  or give off heat to the battery cells  58 , the fluid F exiting through the outlet  81  can have a different temperature than the fluid F entering through the inlet  79 . In one non-limiting embodiment, the battery arrays  56  of the battery assembly  54  are positioned atop the thermal exchange plate assembly  70  so that the thermal exchange plate assembly  70  is in contact with a bottom surface of each battery cell  58 . 
       FIG. 3  illustrates an example thermal exchange plate assembly  70 . In  FIG. 3 , the thermal exchange plate assembly  70  includes a wire mesh structure  84 , which facilitates an exchange of thermal energy between the battery cells  58  and the thermal exchange plate assembly  70 . Fluid F flowing through the thermal exchange plate assembly  70  flows through the mesh structure  84 . In particular, the fluid F flows over the wires of the wire mesh structure  84 . 
     In this example, the wire mesh structure  84  is provided between first and second facesheets  86 ,  88  of the thermal exchange plate assembly  70 . The first facesheet  86  is a top facesheet in this example, and is in contact with a bottom of the battery cells  58 . In one example, the first facesheet  86  is in contact with the bottom of the battery cells  58  by way of an intermediate layer of a thermally insulating material. The second facesheet  88  is a bottom facesheet and is provided on an opposite side of the wire mesh structure  84  of the first facesheet  86 . The first and second facesheets  86 ,  88  provide upper and lower boundaries for a fluid flow path  90 . The fluid flow path  90  is also bounded on the sides by the walls  65  of the enclosure assembly  60 . Alternatively, the sides of the fluid flow path  90  could be bounded by dedicated walls separate from the walls  65  of the enclosure assembly  60 . 
     In this example, the wire mesh structure  84  spans the entire distance D 1  between the first and second facesheets  86 ,  88 , which distributes heat away from the first facesheet  86 , and in turn the battery cells  58 . The wire mesh structure  84  also provides an increased surface area for the fluid F to interact with as it flows through the wire mesh structure  84  along the flow path  90 . Further, the wire mesh structure  84  creates turbulence in the fluid F as the fluid F flows along the flow path  90 , which also increases heat transfer. Thus, the wire mesh structure  84  provides effective and efficient heat transfer. 
     In this example, the wire mesh structure  84  includes a first set of parallel wires  92  spaced-apart from one another and a second set of parallel wires  94 , which are also spaced-apart from one another. The first and second sets of parallel wires  92 ,  94  are interwoven such that they crisscross and overlap one another in an alternating arrangement, and are spaced-apart from one another to provide gaps  96  which allow fluid F to flow over the wires  92 ,  94  while flowing along the fluid flow path  90 . 
     The first and second sets of wires  92 ,  94  are metallic wires, such as copper wires, in this example. This disclosure is not limited to wire mesh structures having copper wires, however, and extends to other types of materials. 
     With reference to  FIG. 4A , in one example the wire mesh structure  84  is initially formed using a bonding technique, such as transient liquid phase (TLP) brazing. In particular, a sintering agent is applied to the wire mesh structure, and heat H and pressure R are further applied to bond the wire mesh structure  84  together. With reference to  FIG. 4B , the facesheets  86 ,  88  are then applied to the wire mesh structure  84  using a bonding technique such as TLP brazing. In this example, pressure R is applied to the facesheets  86 ,  88  and heat H is applied to the overall thermal exchange plate assembly  70 . While TLP brazing is shown and described herein relative to  FIGS. 4A-4B , this disclosure extends to other methods of forming the wire mesh structure  84 . 
       FIGS. 5A-7B  illustrate three example wire mesh structure  84  orientations. While three orientations are illustrated, this disclosure extends to other orientations. With reference to  FIGS. 5A-5B , a first example orientation is a “diamond” orientation. In this orientation, the wire mesh structure  84  provides a plurality of diamond-shaped gaps  96  when viewed in a direction parallel to a plane P of the first facesheet  86 . Reference herein is made to the plane P of the first facesheet  86  for purposes of explanation only. The wire mesh structure  84  also provides diamond-shaped gaps  96  when viewed along the flow path  90 , when viewed in a direction perpendicular to the distance D 1 , etc. 
     With continued reference to  FIGS. 5A-5B , each of the wires in the first set of wires  92  has a respective longitudinal axis A 1  extending at a first acute angle α 1  relative to the P, and each of the wires in the second set of wires  94  has a respective longitudinal axis A 2  extending at a second acute angle α 2  relative to the plane P. In this example, the second acute angle α 2  is provided by reflecting the first acute angle α 1  about an axis A 3  perpendicular to the plane P. 
     As shown in  FIG. 5B , the wire mesh structure  84  includes a plurality of stacks  98  extending along the length L of the thermal exchange plate assembly  70 . In this example, each stack  98  is provided by interweaving a plurality of the first wires  92  with a plurality of the second wires  94 . The length L in this example is parallel to the flow path  90  and perpendicular to the distance D 1 . 
       FIGS. 6A-6B  illustrate a second example orientation of the wire mesh structure  84 . In this example, the wire mesh structure  84  provides a “square” orientation (labeled as “Square A” in  FIG. 6A ), in which the first and second sets of wires  92 ,  94  are interwoven to provide a plurality of square-shaped gaps  96  when viewed parallel to the plane P. In particular, in this example, the wire mesh structure  84  is arranged such that each of wires in the first set of wires  92  has a respective longitudinal axis A 1  extending substantially perpendicular to the plane P. Further, each of the wires in the second set of wires  94  has a respective longitudinal axis A 2  extending substantially parallel to the plane P and perpendicular to the longitudinal axes A 1  of the first set of wires  92 . 
       FIGS. 7A-7B  illustrates the wire mesh structure  84  in a third example orientation. In this orientation, the wire mesh structure  84  has a square orientation when viewed in a direction perpendicular to the plane P (labeled as “Square B” in  FIG. 7A ). The first and second sets of wires  92 ,  94  are arranged similar to the example of  FIGS. 6A-6B , except the wires  92 ,  94  are oriented such that the square-shaped gaps face the first and second facesheets  86 ,  88 . In particular, each of the wires in the first set of wires  92  has a respective longitudinal axis A 1  extending substantially parallel to the plane P (e.g., into the page, relative to  FIG. 7A ), and such that each of the wires in the second set of wires  94  has a respective longitudinal axis A 2  extending both substantially parallel to the plane P and substantially perpendicular to the longitudinal axes A 1 . In this example, the wire mesh structure  84  also provides a plurality of gaps  96  for fluid to flow through. 
     It should be understood that terms such as “top,” “bottom,” “side,” etc., are used above with reference to the normal operational orientation of the battery assembly. Further, these terms have been used herein for purposes of explanation, and should not be considered otherwise limiting. Terms such as “generally,” “substantially,” and “about” are not intended to be boundaryless terms, and should be interpreted consistent with the way one skilled in the art would interpret those terms. 
     Although the different examples have the specific components shown in the illustrations, embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
     One of ordinary skill in this art would understand that the above-described embodiments are exemplary and non-limiting. That is, modifications of this disclosure would come within the scope of the claims. Accordingly, the following claims should be studied to determine their true scope and content.