Patent Publication Number: US-10312559-B2

Title: Battery system

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     The present application is a divisional of U.S. Nonprovisional application Ser. No. 15/675,512, filed Aug. 11, 2017, which is a nonprovisional of and claims priority to U.S. Provisional Application No. 62/384,298, filed Sep. 7, 2016, the entire contents of each of which are hereby incorporated by reference for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     Electric vehicles are growing in popularity as society becomes more and more concerned about carbon emissions and sustainable/renewable energy sources. Electric vehicles operate using electric power stored in one or more batteries. During operation, the stored electrical energy is controllably released to drive an electric motor. The electric motor converts the electrical energy into mechanical energy, which propels the vehicle. Electric vehicles control the flow of power from the battery with switches. As the battery releases electrical power the internal resistance of the battery creates heat. 
     SUMMARY OF THE INVENTION 
     The embodiments discussed below include a battery system for an electric vehicle. The battery system includes first and second busbars that couple to respective positive and negative battery cell terminals. The first and second busbars enable electricity to flow from the battery cells during discharge and electricity to flow to the battery cells during recharge. Coupled to the first and/or second busbars are one or more energy transfer conduits. These energy transfer conduits carry a fluid that enables energy transfer to and/or from the first and second busbars as well as the cells. For example, the fluid flowing through the energy transfer conduits may cool the busbars by removing thermal energy. Likewise, the fluid flowing through the energy transfer conduits may also heat the busbars and/or battery cells. The battery system may therefore regulate the temperature of the battery cells to facilitate battery performance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various features, aspects, and advantages of the present invention will be better understood when the following detailed description is read with reference to the accompanying figures in which like characters represent like parts throughout the figures, wherein: 
         FIG. 1  is a perspective view of an embodiment of an electric vehicle with a powertrain system and a battery system; 
         FIG. 2  is a perspective view of an embodiment of an electric vehicle battery system; 
         FIG. 3  is a side view of an embodiment of a plurality of battery cells within line  3 - 3  of  FIG. 2 ; 
         FIG. 4  is a sectional view of an embodiment of a battery cell within line  4 - 4  of  FIG. 3 ; 
         FIG. 5  is a side view of an embodiment of a plurality of battery cells; 
         FIG. 6  is a cross-sectional view of an embodiment of a busbar along line  6 - 6 ; 
         FIG. 7  is a sectional view of an embodiment of a battery cell within line  7 - 7  of  FIG. 5 ; 
         FIG. 8  is a side view of an embodiment of a plurality of battery cells; 
         FIG. 9  is a perspective view of a cooling plate; 
         FIG. 10  is a perspective view of a cooling plate with battery cells; and 
         FIG. 11 . is a sectional view of an embodiment of a battery cell within line  11 - 11  of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION 
     One or more specific embodiments of the present invention will be described below. These embodiments are only exemplary of the present invention. Additionally, in an effort to provide a concise description of these exemplary embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
       FIG. 1  is a perspective view of an electric vehicle  2 . The electric vehicle  2  includes an powertrain system  4  which may include a front powertrain  6  and/or a rear powertrain  8 . In an embodiment that includes a front and rear powertrain  6 ,  8 , the front powertrain  6  drives the front wheels while the rear powertrain  8  drives the rear wheels. The powertrain system  4  is powered with a battery system  10  that provides power to electric motors in the powertrain system  4 . The battery system  10  may also power various onboard systems such as displays, climate control systems, speakers, radios, etc. 
       FIG. 2  is a perspective view of an embodiment of the battery system  10 . The battery system  10  includes various connectors that electrically connect the battery system  10  to the vehicle  2 , while various contactors control the release of power from the battery system  10 . 
     As illustrated, the battery system  10  includes a housing  12  with a first battery housing member  14  and a second battery housing member  16 . The first and second battery housing members  14 ,  16  may couple together in a variety of ways including threaded fasteners, welding, etc. to form the housing  12 . The battery housing  12  houses a variety of components including battery cells  18  (e.g., 1, 2, 3, 4, 5, 10, 15 or more cells), contactors  20 , connectors  22 , wires, sensors, etc. that work together to connect the stored electrical energy in the battery cells  18  to various vehicle systems (e.g., AC compressor, motors, heating system) as well as to recharge the battery cells  18  for future use. 
     The battery housing  12  may include sections/portions that may be integrally formed into the housing  12 . The sections/portions may form sub-housings/compartments for various electrical components within the housing  12 . As illustrated, the housing  12  includes integral housings/compartments  24 ,  26 . These housings/compartments  24 ,  26  are at respective ends  28 ,  30  of the battery system  10 . By positioning the housings/compartments  24 ,  26  at respective ends  28 ,  30  of the housing  12 , the housing  12  may facilitate connection of the battery system  10  to various systems on the electrical vehicle  2 . However, in some embodiments the housings/compartments  24 ,  26  may be positioned at other locations on the housing  12  (e.g., center, sides). 
     As explained above, the battery cells  18  may optimally operate between 20° C.-35° C. Temperatures above or below this range may negatively affect operation of the battery cells  18 . For example, if the battery cells  18  operate in high temperatures the elevated temperatures may decrease the service life of the battery cells  18  (i.e., may more rapidly lose the ability to hold a charge). In contrast, if the battery cells  18  operate in cold temperatures the electrical resistance increases which may reduce performance. 
     In order to regulate the temperature of the battery cells  18  and increase performance, the vehicle may  4  may include a temperature control system  32 . In operation, the temperature control system  32  regulates the temperature of the battery cells  18  by pumping a fluid  34  through the housing  12 . The fluid  34  may include, water, coolant, oil, or a combination thereof. The fluid  34  is pumped with one or more pumps  36  through an inlet  38  in the housing  12 . Inside the housing  12  the fluid  34  circulates to either warm or cool the battery cells  18  (i.e., regulate the temperature of the battery cells  18 ). After passing through the housing  12 , the fluid  34  exits through outlet  40 . In order to heat or cool the fluid  34 , the fluid  34  passes through one or more heat exchangers  42 . The heat exchangers  42  may be located at various points along the fluid flow path. For example, the heat exchanger  42  may be positioned to exchange energy (e.g., heat or cool) with the fluid stream before it enters the pump  36 . In another embodiment, the heat exchanger  42  may exchange energy with the fluid  34  after it exits the pump  36 . In some embodiments, the temperature control system  32  may include two heat exchangers  42 , one that exchanges energy with the fluid stream before it enters the pump  36  and another that exchanges energy with the fluid stream after it exits the pump  36 . 
     The temperature control system  32  controls the amount of fluid  34  flowing through the housing  12  by controlling the speed of the pump  36  with the controller  44 . In some embodiments, the controller  44  may control one or more valves alone or in combination with the pump  36  to regulate the flow of the fluid  34 . The controller  44  includes one or more processors  46  that execute instructions stored on one or more memories  48  to control operation of the pump  44 . In some embodiments, the controller  44  may also control operation of the heat exchanger  42 . For example, the controller  44  may control the operation of valves to increase or limit the flow of another fluid through the heat exchanger  42 . In some embodiments, the controller  44  may receive signals from temperature sensors  50  representative of battery cell temperatures. The temperature control system  32  may include multiple temperature sensors  50  (e.g., 1, 2, 3, 4, 5, or more) enabling both targeted and redundant monitoring of the battery cells  18 . In response to signals from the temperature sensors  50 , the controller  44  controls the speed of the pump to increase or decrease the flow of fluid  34  through the housing  12 . Faster fluid flow may result in an increase in energy transfer to or from the fluid  34  to either cool or heat the battery cells  18 . 
       FIG. 3  is a side view of an embodiment of a plurality of battery cells within line  3 - 3  of  FIG. 2 . As illustrated, the battery cells  18  may be cylindrical in shape and form a positive and negative terminal at opposing ends  60 ,  62 . It should be noted that the battery cells  18  may be formed into other shapes as well. In some embodiments, the positive terminal is located at the battery cell end  60  while the negative terminal is located at the battery cell end  62 . In another embodiment, the location of the positive and negative terminals may be reversed with the positive terminal located at end  62  and the negative terminal located at end  60 . To complete the circuit the positive and negative terminals couple to respective first and second busbars  64 ,  66 . The busbars  64 ,  66  are made from a conductive material such as aluminum, copper, nickel coated steel, or a combination thereof. In operation, the busbars electrically couple the battery cells  18  together enabling the battery system  10  to combine the electric power of the battery cells  18  before release. In some embodiments, there may be more than two busbars that connect individual and/or groups of battery cells  18  together. 
     As the battery releases power from the battery cells  18  the internal resistance of the battery cell  18 , the resistance of the busbars  64 ,  66 , the ambient temperature surrounding the housing  12  increases the temperature of the battery cells  18 . As the temperature of the battery cells  18  increase above a threshold level battery performance may decrease. Similarly if the temperature of the battery cell  18  falls below a threshold temperature battery performance may also decrease. Accordingly, the battery system  10  includes one or more energy transfer conduits  68  (e.g., 1, 2, 3, 4, 5, etc.). These energy transfer conduits  68  carry fluid  34  that may heat and/or cool the battery system  10  by removing heat from or warming the battery cells  18 . 
     The conduits  68  may couple to one or both of the busbars  64 ,  66 . For example, in some embodiments the battery system  10  may include a single energy transfer conduit  68  coupled to the busbar  64 . In another embodiment, the battery system  10  may include a single energy transfer conduit  68  coupled to the busbar  66 . In some embodiments, a single energy transfer conduit  68  may couple to both the busbars  64 ,  66 . In still another embodiment, each of the busbars  64 ,  66  may include multiple energy transfer conduits  68 . These energy transfer conduits  68  may be integrally formed with or otherwise coupled to the busbars  64 ,  66  (e.g., weld). When formed or coupled, the energy transfer conduits  68  form a protrusion. 
     As illustrated, busbar  64  defines an interior surface  70  and an exterior surface  72 . The busbar  66  likewise defines an interior surface  74  and an exterior surface  76 . The energy transfer conduits  68  may couple to the interior surfaces  70 ,  74  and/or to the exterior surfaces  72 ,  76 . In embodiments where the energy transfer conduits  68  couple to the exterior surfaces  72 ,  76  the cells  18  may be more densely packed, while embodiments that have conduits coupled to the interior surfaces  70 ,  74  may decrease the overall thickness of the battery system  10 . To increase energy transfer from the cells  18  to the energy transfer conduits  68 , the interior surfaces  70 ,  74  of the busbars  64 ,  66  may be coated with a thermally conductive resin or layer that increases energy transfer to the busbars  64 ,  66  which in turn transfer energy to or from the energy transfer conduits  68 . The resin may include any desired resin. 
       FIG. 4  is a sectional view of an embodiment of a battery cell within line  4 - 4  of  FIG. 3 . As illustrated, the energy transfer conduit  68  couples to the interior surface  74  of the busbar  66 . In this position, the energy transfer conduit  68  may weave in-between the cells  18  to facilitate energy transfer from the cells  18  and reduce the overall thickness of the battery system  10 . In some embodiments, the energy transfer conduit  68  may define a rectangular or square cross-section. However, in some embodiments the cross-section of the energy transfer conduit  68  may be semi-circular, trapezoidal, etc. To reduce the space taken by the energy transfer conduit  68  the length  90  may be greater than the width  92 . This enables the energy transfer conduit to extend further between the busbar  64  and the busbar  66  as well as increase the surface area exposed to the cells  18 . The length  90  may be any desired length and the width  92  may be any desired width. In some embodiments, the exterior surface  94  of the energy transfer conduit may be coated in a thermally conductive resin or coating  96  that facilitates energy transfer from the cells  18  to the fluid  34  carried in the energy transfer conduit  68 . 
       FIG. 5  is a side view of an embodiment of a plurality of battery cells  18  coupled to busbars  64 ,  66 . Instead of energy transfer conduits  68  coupled to exterior surfaces of the busbars  64 ,  66 , the energy transfer conduits  68  may extend through the busbars  64 ,  66 . In this way the busbars  64 ,  66  may have uniform widths  120 ,  122 . As illustrated, the busbars  64 ,  66  may have the same widths  120 ,  122 , but in other embodiments one of the busbars  64 ,  66  may have a width  120 ,  122  greater than the other busbar  64 ,  66 . By increasing the thickness of one of the busbars  64 ,  66  may accommodate a larger energy transfer conduit  68 . For example, the upper busbar (e.g., either busbar  64 ,  66  depending on orientation) may have a larger width to accommodate a larger energy transfer conduit  68  (e.g., width). 
       FIG. 6  is a cross-sectional view of an embodiment of a busbar  64 ,  66  along line  6 - 6 . As illustrated, the energy transfer conduit  68  may weave within the busbar  64 ,  66 . However, in other embodiments, there may be a plurality of conduits  68  that extend through the busbar  64 ,  66  at regular or irregular intervals (e.g., straight, angled). These conduits  68  may be isolated from one another or secondary conduits may fluidly connect them together. In another embodiment, the conduit  68  may extend substantially the entire distance between the sides  140  and  142  of the busbar  64 ,  66 . 
       FIG. 7  is a sectional view of an embodiment of a battery cell within line  7 - 7  of  FIG. 5 . In  FIG. 7  a thermally conductive layer  160  (e.g., resin) may be placed over all or a portion of the busbar  64 ,  66  to facilitate energy transfer from the cells  18  to the busbar  64 ,  66  which transfers the energy to the fluid  34 . Thermally conductive layer  160  may be any desired thick. The thermally conductive layer  160  may be made out of any desired materials. Furthermore, in some embodiments the thermally conductive layer  160  may also be electrically conductive enabling the layer  160  to facilitate electrical connection to the busbars  64 ,  66 . 
       FIG. 8  is a side view of an embodiment of a plurality of battery cells  18 . In  FIG. 8 , both busbars  64 ,  66  are positioned on the same side of the battery cells  18 . That is both positive and negative terminals of the battery cell  18  are positioned at the same end (i.e., either end  60  or  62 ). In this example, the busbars  64 ,  66  are positioned next to end  60  of the battery cells  18 . On the opposite side  62 , the battery system  10  includes an energy transfer plate  170  with one or more energy transfer conduits  68 . In some embodiments, the energy transfer conduit  68  may weave (e.g., serpentine) within the busbar  64 ,  66 . However, in other embodiments, there may be a plurality of conduits  68  that extend through the energy transfer plate  170  at regular or irregular intervals. These conduits  68  (e.g., primary conduits) may be isolated from one another or secondary conduits may fluidly connect the conduits  68  together. In another embodiment, the conduit  68  may be a chamber that extends substantially the entire length and width of the plate  170 . 
     In operation, a fluid circulates through the energy transfer plate  170  drawing or delivering heat to the battery cells  18  enabling the cells  18  to operate within a temperature range (e.g., optimal temperature range). In some embodiments, the energy transfer plate  170  may include a thermally conductive resin or coating  160  that facilitates energy transfer from the battery cell  18  to the energy transfer plate  170  and as a result to the fluid  34 . In some embodiments, the energy transfer plate  170  may define one or more counterbores  172  that receive the ends  62  of the cells  18 . The counterbores  172  have a depth sufficient in order to couple to and stabilize the cells  18 . The depth of the counterbores  172  may also facilitate energy transfer by increasing the contact area between the energy transfer plate  170  and the cells  18 . 
     The first and second busbars  64 ,  66 , are electrically isolated from each other with one or more dielectric material layers  176 . The dielectric layer  176  may include any desired material. While the dielectric layer  176  is electrically non-conductive, the dielectric layer  176  may be thermally conductive enabling heat transfer between the busbars  64 ,  66 , the cell  18  and the energy transfer plate  170 . The dielectric layer  176  defines a plurality of apertures  178  and the first busbar  64  defines a plurality of apertures  180 . These apertures  178  and  180  enable protrusions  182  on the second busbar  66  to contact the cell  18  through the dielectric layer  176  and the first busbar  64 . Depending on the construction of the cell  18  the protrusion  182  may contact the positive or negative terminal, while the first busbar  64  contacts the opposite terminal. The cell  18  includes first and second terminals  184 ,  186  these terminals may be either the positive or negative terminal depending on cell  18  construction. As illustrated, the second busbar  66  electrically contacts the first terminal  184  with the protrusion  182 , while the first busbar  64  contacts the second terminal  186 . 
       FIG. 9  is a perspective view of an energy transfer plate  170 . As explained above, the energy transfer plate  170  includes multiple counterbores  172  that receive respective cells  18 . These counterbores  172  may have the same depth and area. In other embodiments, the counterbores  172  may have different depths and/or different areas to accommodate different sizes of cells  18 . 
       FIG. 10  is a perspective view of the energy transfer plate  170  with battery cells  18 . As illustrated, the cells  18  fit within counterbores  172  of the energy transfer plate  170 . These counterbores  172  enable the cells  18  to be densely packed while also aligning and supporting the cells  18 . 
       FIG. 11 . is a sectional view of an embodiment of a battery cell  18  within line  11 - 11  of  FIG. 8 . In some embodiments, the dielectric layer  176  may also facilitate energy transfer by including one or more energy transfer conduits  68  that carry the fluid  34 . Similar to the discussion above, the energy transfer conduit  68  may weave (e.g., serpentine) within the dielectric layer  176 . However, in other embodiments, there may be a plurality of conduits  68  that extend through the dielectric layer  176  at regular or irregular intervals. These conduits  68  (e.g., primary conduits) may be isolated from one another or secondary conduits may fluidly connect the conduits  68  together. In another embodiment, the conduit  68  may be a chamber that extends substantially the entire length and width of the plate  170 . 
     In addition, it is to be understood that any workable combination of the features and elements disclosed herein is also considered to be disclosed. Additionally, any time a feature is not discussed with regard in an embodiment in this disclosure, a person of skill in the art is hereby put on notice that some embodiments of the invention may implicitly and specifically exclude such features, thereby providing support for negative claim limitations. 
     Having described several embodiments, it will be recognized by those of skill in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the invention. Additionally, a number of well-known processes and elements have not been described in order to avoid unnecessarily obscuring the present invention. Accordingly, the above description should not be taken as limiting the scope of the invention.