Patent Publication Number: US-2022238940-A1

Title: Power battery pack and vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims to the priority of Chinese Patent No “201910544995.0” filed by the BYD Co., Ltd. on Jun. 21, 2019 and entitled “POWER BATTERY PACK AND VEHICLE”, which is incorporated herein by reference in its entirety. 
     FIELD 
     This application belongs to the field of power battery manufacturing technologies, and specifically, to a power battery pack and a vehicle with the power battery pack. 
     BACKGROUND 
     In the related art, cells are first assembled into a module, and are fixed by a module frame. Therefore, mounting space utilization of a power battery pack is low, and a quantity of the cells and the total capacity of the power battery pack are reduced, affecting the battery life. 
     SUMMARY 
     This application adopts the following technical solutions: 
     In view of the foregoing problems, this application provides a power battery pack, including: a tray and an upper cover, where the tray includes a side frame and a bottom plate, and the upper cover and the bottom plate are respectively connected to upper and lower ends of the side frame to define a battery accommodating cavity; and a plurality of cells, where the plurality of cells are mounted in the battery accommodating cavity, one surface of each of the cells and the upper cover are bonded by a structural adhesive, and the other opposite surface of the cell and the bottom plate are bonded by a thermally conductive structural adhesive. 
     The power battery pack in this application reduces the use of a module frame, improves space utilization, reduces parts of the battery pack, saves a process procedure, improves assembly efficiency, and reduces manufacturing costs while ensuring sufficient structural strength. 
     This application further provides a vehicle, including the foregoing power battery pack. 
     Compared with the related art, the vehicle has same advantages as the foregoing power battery pack, and details are not described herein again. 
     Additional aspects and advantages of this application are partially provided in the following description, and some of which will become apparent in the following description or be learned from the practice of this application. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and/or additional aspects and advantages of this application will become apparent and comprehensible in the description of the embodiments made with reference to the following accompanying drawings. 
         FIG. 1  is a top view of a power battery pack according to an embodiment of this application; 
         FIG. 2  is a cross-sectional view along A-A in  FIG. 1 ; 
         FIG. 3  is a partially enlarged view of a position B in  FIG. 2 ; 
         FIG. 4  is an exploded view of a power battery pack according to an embodiment of this application; 
         FIG. 5  is a schematic diagram of an arrangement structure of cells in a power battery pack according to an embodiment of this application; 
         FIG. 6  is a schematic structural diagram of cells in a power battery pack arranged on a tray according to an embodiment of this application; and 
         FIG. 7  is a schematic structural diagram of a vehicle according to an embodiment of this application. 
     
    
    
     REFERENCE NUMERALS 
     vehicle  1000 , power battery pack  100 , tray  110 , side frame  111 , bottom plate  112 , isolation cavity  113 , upper cover  120 , cell  150 , thermally conductive structural adhesive  160 , structural adhesive  161 , and end plate  180 . 
     DETAILED DESCRIPTION 
     Embodiments of this application are described in detail below, and examples of the embodiments are shown in accompanying drawings, where the same or similar elements or the elements having same or similar functions are denoted by the same or similar reference numerals throughout the description. The embodiments described below with reference to the accompanying drawings are exemplary and used merely for explaining this application, and should not be construed as a limitation on this application. 
     Unless otherwise specified, in this application, a front-rear direction is a longitudinal direction of a vehicle  1000 , that is, an X direction; a left-right direction is a lateral direction of the vehicle  1000 , that is, a Y direction; and an up-down direction is a vertical direction of the vehicle  1000 , that is, a Z direction. 
     A power battery pack  100  according to an embodiment of this application is described below with reference to  FIG. 1  to  FIG. 4 . 
     In some embodiments, as shown in  FIG. 1  to  FIG. 4 , a battery pack housing includes a tray  110 , an upper cover  120 , and a plurality of cells  150 . 
     As shown in  FIG. 2  and  FIG. 4 , the tray  110  includes a side frame  111  and a bottom plate  112 . In an actual implementation, the side frame  111  is a rectangular frame, and the bottom plate  112  and a bottom surface of the side frame  111  can be mutually connected through soldering for use as a load bearing structure of the entire pack. In addition, the sealing performance of the entire pack is ensured, and the bottom plate  112  has heat spreading performance, thereby facilitating the heat exchange between the inside of a power battery pack body and the outside by a heat exchange plate. 
     The upper cover  120  and the bottom plate  112  are respectively connected to upper and lower ends of the side frame  111  to define a battery accommodating cavity, and the plurality of cells  150  are mounted in the battery accommodating cavity. 
     The upper cover  120  is connected to the upper end of the side frame  111 , and the upper cover  120  and the side frame  111  may be connected to each other by at least one of a threaded connection member and an adhesive. In an actual implementation, an adhesive can be sandwiched between the upper end of the side frame  111  and a lower surface of the upper cover  120  to implement sealing and preliminary connection, and at least one threaded connection member can also be disposed on an outer ring of the adhesive to further strengthen the connection between the tray  110  and the upper cover  120 . 
     One surface of the cell  150  and the upper cover  120  are bonded by a structural adhesive  161 , and the other opposite surface of the cell  150  and the bottom plate  112  are bonded by a thermally conductive structural adhesive  160 . 
     According to the power battery pack  100  provided in this application, the plurality of cells  150  are directly mounted in the battery accommodating cavity without being assembled into a module first, so that the use of a module frame is reduced, a mounting space of the cells  150  in a power battery pack housing is increased, and a quantity of the cells  150  mounted in the battery accommodating cavity is increased, thereby improving the total capacity and battery life of the power battery pack  100 . 
     In addition, in the related art, the cells need to be first assembled into the module, and the module is always in irregular shape and cannot tightly arrange in the power battery pack housing. However, in the solutions of this application, the cells  150  are directly mounted in an accommodating space defined by the tray  110  and the upper cover  120 , so that the cells  150  may tightly arrange in the battery accommodating cavity, thereby further increasing the mounting space of the cells  150  in the battery accommodating cavity and the quantity of the cells  150  in the entire power battery pack. 
     In addition, the use of the module frame is reduced, a quantity of elements and assembly procedures are reduced, and costs are further reduced. One surface of the cell  150  and the upper cover  120  are bonded by the structural adhesive  161 , and the other opposite surface of the cell  150  and the bottom plate  112  are bonded by the thermally conductive structural adhesive  160 . In this case, the fixing of the cells in the battery accommodating cavity is strengthened, and the strength of the entire power battery pack is improved. In addition, because the other opposite surface of the cell  150  and the bottom plate  112  are bonded by the thermally conductive structural adhesive, the heat of the battery may further be transferred to the bottom plate through the thermally conductive structural adhesive and be dissipated through the bottom plate. 
     According to the power battery pack  100  provided in this application, as shown in  FIG. 5 , the cell  150  can be a rectangular battery of a cuboid structure and has a length L, a thickness D, and a height H between the length and the thickness, and the plurality of cells  150  are arranged along a thickness direction of the cells. The cell  150  has two opposite large surfaces and two opposite narrow surfaces. A long side of the large surface is the length of the cell  150 , and a short side is the height of the cell  150 . A long side of the narrow surface is the length of the cell  150 , and a short side is the thickness of the cell  150 . Two adjacent cells  150  are arranged in the battery accommodating cavity with large surfaces facing each other. As shown in  FIG. 6 , an end plate  180  may be mounted on an outer side of two outermost cells  150  along the thickness direction of the cell  150 , and the cell  150  may be connected to the tray  110  by the end plate  180 . 
     According to an embodiment of this application, one narrow surface of the cell  150  and the bottom plate  112  are bonded by the thermally conductive structural adhesive  160 , and the other narrow surface of the cell  150  and the upper cover  120  are bonded by the structural adhesive  161 . 
     In this application, the upper cover  120  and the bottom plate  112  are both made of a metal. 
     In one aspect, the bottom plate  112  and the upper cover  120  made of a metal can provide protection for the inner cells  150 . In another aspect, the battery accommodating cavity can implement heat dissipation. The bottom plate  112  and the upper cover  120  may be made of a metal with high thermal conductivity, including, but not limited to, aluminum, copper, and an alloy thereof. 
     In an actual implementation, the bottom plate  112  and the upper cover  120  may be made of an aluminum alloy material with adequate heat conduction performance and a low density. 
     The structural adhesive  161  is disposed between one surface of the cell  150  and the upper cover  120 , and the thermally conductive structural adhesive  160  is disposed between the other opposite lower surface of the cell  150  and the bottom plate  112 . In other words, one upper surface of the cell  150  is bonded to the upper cover  120  by the structural adhesive  161 , and the other opposite lower surface of the cell  150  is bonded to the bottom plate  112  by the thermally conductive structural adhesive  160 . In this case, upper and lower ends of two opposite surfaces of the cell  150  are both bonded to the battery pack housing, thereby strengthening the fixing of the cells  150 , so that the cells  150  in the power battery pack  100  are fixed and stable, and the strength of the entire power battery pack is improved. 
     According to another aspect, one of the surfaces of the cell  150  is bonded to the bottom plate by the thermally conductive structural adhesive  160 . The thermally conductive structural adhesive  160  can prevent the cell  150  from being electrically conducted to the tray  110 , increase a contact area between the cell  150  and the tray  110 , and transfer the heat of the battery to the bottom plate, so that the heat is dissipated through the bottom plate, thereby implementing heat dissipation. 
     In an actual implementation, a thermally conductive insulating adhesive may be a thermally conductive silicone which has better insulation and thermal conductivity performance, and can transfer heat of the cell  150  to the bottom plate  112  in time. The structural adhesive may be formed by adding an inorganic thermally conductive filler such as an aluminum oxide to one of epoxy resin, polyurethane, modified silane, acrylic, and silicone rubber. 
     As shown in  FIG. 2  and  FIG. 3 , the power battery pack  100  in this application may further include a bottom protection plate and a heat exchange plate. 
     The bottom protection plate is connected to the lower end of the side frame  111 , and is spaced apart from the bottom plate  112  along a vertical direction, so that a cavity is formed between the bottom protection plate and the bottom plate  112 , and the heat exchange plate is sandwiched between the bottom protection plate and the bottom plate  112 . 
     The heat exchange plate may be provided with a heat exchange cavity, configured to circulate a heat exchange medium. In an actual implementation, the heat exchange plate may be a hollow plate body. The heat exchange plate is provided with a flow channel configured to circulate the heat exchange medium, and the heat exchange medium may be water. 
     It may be understood that, the bottom protection plate and the bottom plate  112  are equivalent to a sandwiched structure on a bottom surface of the tray  110 . In this case, the heat exchange plate is disposed outside relative to the battery accommodating cavity, and the electrical safety of the power battery pack  100  can be effectively ensured in case that a cooling liquid suddenly leaks. 
     For example, in some embodiments, the power battery pack  100  is mounted on a chassis of the vehicle  1000 . In a travel process of the vehicle  1000 , if a bump on the road hits the power battery pack  100  and causes damage to the heat exchange plate, because the heat exchange plate and the battery accommodating cavity are separated by the bottom plate  112 , the heat exchange medium is kept from flowing into the battery accommodating cavity to protect the cell  150  from impact. 
     According to another aspect, the bottom protection plate may protect the heat exchange plate to some extent, to prevent the heat exchange plate from damage. 
     As shown in  FIG. 2 , the side frame  111  may be provided with an isolation cavity  113 . An end of the heat exchange plate extends into the isolation cavity  113 . The heat exchange plate may include a plurality of heat exchange flow channels. A collecting pipe is disposed at the end of the heat exchange plate. The collecting pipe is disposed in the isolation cavity  113 , and is in communication with an external water passage through a joint passing through the side frame  111 . 
     In an embodiment of this application, the side frame  111  may be made of aluminum. The side frame is provided with a cavity structure, and a lower end of one of cavities is open. The collecting pipe may be mounted in the cavity through the open end below, and the cavity is sealed when bottoms of the bottom protection plate and the side frame  111  are connected, so that the isolation cavity  113  is formed. 
     It may be understood that, an inner circuit is kept from being impact with the presence of the structure of the isolation cavity  113  even if leakage occurs at the collecting pipe, and it is equivalent that the collecting pipe is mounted in the side frame  111  without affecting the battery density of the entire power battery pack  100 . 
     For the power battery pack  100  provided in this application, the electrical safety of the power battery pack  100  can be effectively ensured by arranging the heat exchange plate between the bottom plate  112  and the bottom protection plate, and the bottom protection plate can protect the heat exchange plate to some extent. The external heat exchange plate does not occupy a space of the battery accommodating cavity, and the battery density of the entire power battery pack  100  is higher. 
     In some embodiments, a surface of the heat exchange plate and an outer surface of the bottom plate  112  are bonded by a thermally conductive structural adhesive  160 . In this case, an actual effective contact area between the heat exchange plate and the bottom plate  112  is large, to increase heat transfer. 
     In some embodiments of this application, the heat exchange plate is provided with an energy-absorbing structure. The heat exchange plate is an integrated structure with the flow channels disposed inside, and an isolation rib between adjacent flow channels may form the energy-absorbing structure, so that the entire structure of the heat exchange plate  130  also implements an energy-absorbing effect. 
     In some embodiments, the bottom protection plate includes a mainboard body and a heat preservation layer. The heat preservation layer is disposed on a side of the mainboard body close to the heat exchange plate. The mainboard body may be a metal plate, including a structure such as a steel plate, and can implement anti-collision. The heat preservation layer may be a structure such as heat preservation cotton. In this case, the bottom protection plate has excellent mechanical strength while reducing the heat exchange between the pack body and the outside. 
     In some embodiments, the bottom protection plate includes a mainboard body and a buffer layer. The buffer layer is disposed on a side of the mainboard body close to the heat exchange plate. The mainboard body may be a metal plate, including a structure such as a steel plate, and can implement anti-collision. The buffer layer is configured to absorb external impact, and includes a structure such as a rubber layer. In this case, the bottom protection plate has excellent mechanical strength and mechanical impact resistance. 
     A power battery pack  100  includes a tray  110  and an upper cover  120 , where the tray  110  includes a side frame  111  and a bottom plate  112 , and the upper cover  120  and the bottom plate  112  are respectively connected to upper and lower ends of the side frame  111  to define a battery accommodating cavity; and a plurality of cells  150 , where the plurality of cells  150  are mounted in the battery accommodating cavity, one surface of each of the cells  150  and the upper cover  120  are bonded by a structural adhesive  161 , and the other opposite surface of the cell  150  and the bottom plate  112  are bonded by a thermally conductive structural adhesive  160 . 
     In some embodiments, the cell  150  is a rectangular battery of a cuboid structure and has a length, a thickness, and a height between the length and the thickness, and the plurality of cells  150  are arranged along a thickness direction of the cells. 
     In some embodiments, the cell  150  has two opposite large surfaces and two opposite narrow surfaces; a long side of the large surface is the length of the cell  150 , and a short side is the height of the cell  150 ; and a long side of the narrow surface is the length of the cell  150 , and a short side is the thickness of the cell  150 . 
     In some embodiments, two adjacent cells  150  are arranged in the battery accommodating cavity with large surfaces facing each other. 
     In some embodiments, one narrow surface of the cell  150  and the upper cover  120  are bonded by the structural adhesive  161 ; and the other narrow surface of the cell  150  and the bottom plate  112  are bonded by the thermally conductive structural adhesive  160 . 
     In some embodiments, the upper cover  120  and the bottom plate  112  are both made of a metal. 
     In some embodiments, the power battery pack  100  further includes: a bottom protection plate, connected to the lower end of the side frame  111 , and spaced apart from the bottom plate  112  along a vertical direction; and a heat exchange plate, sandwiched between the bottom protection plate and the bottom plate  112 . 
     In some embodiments, a surface of the heat exchange plate and an outer surface of the bottom plate  112  are bonded by a thermally conductive structural adhesive  160 . 
     In some embodiments, the heat exchange plate is provided with a heat exchange cavity, configured to circulate a heat exchange medium. 
     In some embodiments, the heat exchange plate is provided with an energy-absorbing structure. 
     In some embodiments, the bottom protection plate includes a mainboard body and a heat preservation layer, and the heat preservation layer is disposed on a side of the mainboard body close to the heat exchange plate. 
     In some embodiments, the bottom protection plate includes a mainboard body and a buffer layer, and the buffer layer is disposed on a side of the mainboard body close to the heat exchange plate. 
     This application further discloses a vehicle  1000 . 
     As shown in  FIG. 7 , the vehicle  1000  according to the embodiments of this application includes the power battery pack  100  in any one of the foregoing embodiments. 
     The vehicle  1000  according to the embodiments of this application may be an electric vehicle  1000 , including an electric passenger vehicle, an electric bus, or the like. 
     In some embodiments, the power battery pack  100  may be mounted on the chassis of the vehicle  1000 . 
     In the descriptions of this specification, descriptions using reference terms “an embodiment”, “some embodiments”, “an exemplary embodiment”, “an example”, “a specific example”, or “some examples” mean that specific characteristics, structures, materials, or features described with reference to the embodiment or example are included in at least one embodiment or example of this application. In this specification, exemplary descriptions of the foregoing terms do not necessarily refer to the same embodiment or example. In addition, the described specific features, structures, materials, or characteristics may be combined in a proper manner in any one or more of the embodiments or examples. 
     Although the embodiments of this application have been shown and described, a person of ordinary skill in the art should understand that various changes, modifications, replacements and variations may be made to the embodiments without departing from the principles and spirit of this application, and the scope of this application is as defined by the appended claims and their equivalents.