Patent Document

BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to a battery cooling structure for cooling a battery mounted in a vehicle. 
         [0003]    2. Description of Related Art 
         [0004]    Vehicles such as hybrid vehicles (HV) and electric vehicles (EV) run by driving a motor using electric power from a battery. Therefore, a battery that ensures the necessary electric power is mounted in the vehicle. Also, in order to improve the battery mounting space efficiency, Japanese Patent Application Publication No. 2010-036723 (JP 2010-036723 A) proposes to house the battery under a rear seat. Also, a battery generates heat as it charges and discharges. In particular, with a battery for a vehicle, large current often flows, so the amount of heat generated is large. If the temperature of the battery becomes high, the battery will deteriorate, so it is necessary to provide a structure to cool the battery. JP 2010-036723 A describes a structure that draws air into a vehicle cabin from in front of a lower portion of the rear seat, and discharges this air out of the vehicle from behind a lower portion of the rear seat. 
       SUMMARY OF THE INVENTION 
       [0005]    Here, if exhaust air that has cooled the battery under the rear seat is discharged out of the vehicle as it is, the exhaust passage is able to be short, which is advantageous in terms of space, and pressure loss is low, so it is efficient. However, with this configuration, an exhaust vent is arranged in a relatively low position, so sufficient consideration must be given so that foreign matter and water and the like on the road does not get into the battery pack. 
         [0006]    Therefore, one aspect of the invention relates to a battery cooling structure  for cooling a battery mounted in a vehicle. This battery cooling structure includes a battery pack, an air supplying device, and an air exhausting device. The battery pack houses the battery in an internal space, and is arranged under a rear seat of the vehicle. The air supplying device is configured to send cooling air to the battery pack. The air exhausting device is configured to discharge exhaust air from the battery pack. An exhaust vent that discharges the exhaust air is provided in a floor surface in a rearward space behind the rear seat in the vehicle. The exhaust vent is configured to discharge the exhaust air from the battery pack upward into the rearward space from the exhaust vent. 
         [0007]    Also, in the battery cooling structure described above, the rearward space may be a luggage space of the vehicle, and a spare tire housing space may be provided in a lower portion of the luggage space. Also, the exhaust vent may be positioned in front of the spare tire housing space. 
         [0008]    Also, in the battery cooling structure described above, the air exhausting device may have an exhaust air duct that extends from the battery pack to the rearward space, and an exhaust port of the exhaust air duct may be provided underneath the floor surface and open into a discharge duct that extends in a vehicle width direction. The discharge duct may have a discharge port in a position planarly offset with respect to the exhaust port on a front surface side of the discharge duct. After exhaust air discharged from the exhaust port of the exhaust air duct flows through the discharge duct in a direction parallel to the floor surface in the vehicle width direction, the exhaust air may be discharged upward into the rearward space via the discharge port and the exhaust vent. 
         [0009]    Also, in the battery cooling structure described above, the discharge port of the exhaust air duct may be covered by cloth. Also, in the battery cooling structure described above, the discharge port of the exhaust air duct may be covered by lattice. Furthermore, in the battery cooling structure described above, the discharge port of the exhaust air duct may be provided in a direction excluding in front, with respect to a vehicle longitudinal direction, of the exhaust port, and a closed portion may be provided in front, with respect to the vehicle longitudinal direction, of the exhaust port. 
         [0010]    This kind of battery cooling structure makes it possible to effectively inhibit foreign matter and the like from getting in through the exhaust vent. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Features, advantages, and technical and industrial, significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: 
           [0012]      FIGS. 1A and 1B  are views illustrating the flow of supply air and exhaust air to and from a battery pack according to a battery cooling structure of one example embodiment of the invention; 
           [0013]      FIG. 2  is a view of the exterior of the battery pack and a duct according to the battery cooling structure of the example embodiment; 
           [0014]      FIGS. 3A, 3B, and 3C  are views of the structure of an exhaust air duct behind a rear seat according to the battery cooling structure of the example embodiment; and 
           [0015]      FIGS. 4A, 4B, and 4C  are views of the exterior of the exhaust air duct, a supply air duct, a blower, and an intake air duct according to the battery cooling structure of the example embodiment. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0016]    Hereinafter, example embodiments of the invention will be described with reference to the accompanying drawings. The invention is not limited to the example embodiments described here. 
         [0017]    First, the structure related to supply air and exhaust air in a battery cooling structure of this example embodiment will be described.  FIGS. 1A and 1B  are views of the structure related to the flow of supply air and exhaust air to and from a battery pack in this example embodiment. 
         [0018]    A rear seat  10  includes a seat cushion  10   a,  a seatback  10   b,  and a battery housing space  10   c  below the seat cushion  10   a.  The front and sides of the battery housing space  10   c  are surrounded by a lower trim  12 . Also, a vehicle body  14  is positioned on a bottom surface side of the battery housing space  10   c.    
         [0019]    A battery pack  20  is arranged inside of the battery housing space  10   c,  and a battery stack  22  is arranged inside of this battery pack  20 . This battery stack  22  is formed by a plurality of battery modules  24  connected together in series. 
         [0020]    The inside of the battery pack  20  is sealed by a lower case and an upper cover. A supply air flow path is formed above the battery stack  22  and an exhaust air flow path is formed below the battery stack  22 . 
         [0021]    A supply air duct  26  is connected to a rear side of the supply air flow path above the battery stack  22  inside the Battery pack  20 , as shown in  FIG. 1A , and this supply air duct  26  extends toward the rear and is connected to a blowing side of a blower  28 . 
         [0022]    An exhaust air duct  30  is connected to a rear side of the exhaust air flow path below the battery stack  22  of the battery pack  20 , as shown in  FIG. 1B , and this exhaust air duct  30  extends toward the rear, with an exhaust port  32  opening upward. 
         [0023]    A rear side (back) space of the seatback  10   b  of the rear seat  10  serves as a luggage space  40 . A floor surface of the luggage space  40  is formed by a deck board  42 . This deck board  42  is placed in the luggage space  40 , so it is able to be picked up and removed. A spare tire space  44  within which a spare tire is housed is provide below the deck board  42 , and a spare tire is housed here: Also, an accessories compartment such as a shelf is provided below the deck board  42 , at a front upper portion in the, spare tire space  44 . 
         [0024]    Also, the blower  28  described above is arranged behind the rear seat  10  and in front of the spare tire space  44 . That is, there is a space below the luggage space  40  to the rear of the rear seat  10  and in front of the spare tire space  44 , and the blower  28  is arranged here. An intake air duct  60  (see  FIG. 2 ) and the supply air duct  26  are connected to this blower  28 . Also, a rear side portion of the exhaust air duct  30  and the exhaust port  32  are provided. A discharge duct  48  that extends in a vehicle width direction is provided on an upper portion of this exhaust port  32 , and a discharge port panel  50  is provided on a front surface of this discharge duct  48 . This discharge port panel  50  has a closed portion and an open portion. The open portion is an exhaust port. An exhaust vent  54  formed by a gap between a tip end of the deck board  42  and a back surface of the seatback  10   b  above this exhaust port is open to the luggage space  40 . A seat member  52  is provided between a lower front end of the discharge duct  48  and the back surface of the seatback  10   b  so that articles will not fall down. 
         [0025]    Here,  FIG. 2  is a perspective view of the battery pack  20  and a duct. In this case, the intake air duct  60  is connected to the intake side of the blower  28 . This intake air duct  60  draws in air from an inlet  62  in a side surface on the door side of lower trim of the rear seat  10 . In  FIG. 2 , the seat cushion  10   a  and the lower trim  12  and the like shown in  FIGS. 1A and 1B  have been removed, but the inlet  62  is open to the door-side side surface of the lower trim  12 . Cloth or lattice or the like is placed over the front surface of the inlet  62  to prevent foreign matter from getting in from the outside. 
         [0026]    In this way, the intake air duct  60 , the supply air duct  26 , and the exhaust air duct  30  are arranged in order from the door side toward the inside, in the space below the seat cushion  10   a  of the rear seat  10 . 
         [0027]    Next, the structure to the rear of the battery cooling structure of this example embodiment will be described. Here,  FIGS. 3A, 3B, and 3C  are views of the structure of a portion where the exhaust port  32  opens out. In  FIG. 3A , the top of the drawing is toward the vehicle rear and the side of the drawing is in the vehicle width direction. In  FIG. 3B , the top of the drawing is upward with respect to the vehicle, and the side of the drawing is in the vehicle width direction. In  FIG. 3C , the top of the drawing is upward with respect to the vehicle, the left side of the drawing is toward the vehicle front, and the right side of the drawing is toward the vehicle rear. 
         [0028]    In this way, the exhaust port  32  is provided in front of an accessories compartment  46 , and is open to a bottom surface of the discharge duct  48  that extends in the width direction of the vehicle. This discharge duct  48  has the discharge port panel  50  on the front side. This discharge port panel  50  has a discharge port  50   a  that is covered by cloth or lattice or the like, and a closed portion  50   b.  This discharge port  50   a  is provided somewhere other than on (i.e., in a location excluding) the front side of the exhaust port  32 . The front of the exhaust port  32  is the closed portion  50   b.  The discharge port panel  50  may be formed by a panel in which the discharge port  50   a  is formed as an opening, or the closed portion  50   b  may be arranged at appropriate intervals so as to form an open portion (i.e., the discharge port  50   a ) therebetween. 
         [0029]    Therefore, after exhaust air from the exhaust port  32  temporarily curves in the width direction of the vehicle, it then flows forward toward the back surface of the seatback  10   b  of the rear seat  10 . The exhaust air then passes through the exhaust vent  54  that is the gap between the tip end of the deck board  42  and the back surface of the seatback  10   b,  and is discharged upward into the luggage space  40 . 
         [0030]    Cloth or lattice may also be arranged on the upper surface of the exhaust port  32  so that articles will not fall into the exhaust port  32 . Also, the discharge port panel  50  is preferably able to be removed from the discharge duct  48 . Further, the upper end of the exhaust port  32  is flange-shaped and positioned above the bottom surface of the discharge duct  48 . By having this portion extend upward in a pipe-shape, water and the like will not reach the exhaust port  32  even if it gets into the discharge duct  48 . 
         [0031]    Next, the flow of air in the battery cooling structure of this example embodiment will be described. Air inside the vehicle cabin is drawn in from the inlet  62  by driving the blower  28 . This air is drawn into the blower  28  via the intake air duct  60 . Discharged air from the blower  28  is supplied into an upper space (i.e., a supply air flow path) in the battery pack  20  via the supply air duct  26 . The battery stack  22  is arranged inside the battery pack  20 , but because there is a gap between battery modules  24  of the battery stack  22 , the air flows downward through this gap, such that the battery modules  24  are effectively cooled. Here, cooling air is able to be made to pass through this gap between the stacked battery modules  24  by closing off the area between the periphery of the battery stack  22  and a peripheral inside wall of the battery pack  20 . 
         [0032]    Exhaust air is discharged from a lower space (i.e., an exhaust air, flow path) in the battery pack  20  into the luggage space  40  through the exhaust air duct  30 , the exhaust port  32 , the discharge duct  48 , the discharge port panel  50 , and the exhaust vent  54  that is the gap between the tip end of the deck board  42  and the back surface of the seatback  10   b.  In this example, the exhaust vent  54  is positioned along almost the entire width in the width direction of the vehicle, but it may also be limited to only a specific portion. 
         [0033]    Next, the individual structures of the battery cooling structure of this example embodiment will be described. In  FIGS. 1A and 1B , only one rear seat  10  is shown, but normally there are two rear seats  10 , and battery packs  20 , as well as a mechanism for cooling the battery packs  20 , are arranged with the same configuration under the rear seats  10 , as shown in  FIGS. 1A and 1B . 
         [0034]    Here,  FIGS. 4A, 4B, and 4C  are views of the exteriors of the exhaust air duct  30 , the supply air duct  26 , and the intake air duct  60 , respectively. As shown in  FIG. 4A , the exhaust air duct  30  extends toward the rear from a rear end of a lower case that forms a bottom surface of the battery pack  20 . As shown in the drawing, a front end of the exhaust air duct  30  is a flat opening that is vertically narrow (i.e., narrow in the vehicle height direction) and wide (in the vehicle width direction). Air from the whole discharge flow path below the battery stack  22  is discharged from this opening. The width of the exhaust air duct  30  gradually narrows toward the exhaust port  32 , and the exhaust port  32  is a generally square-shaped opening. 
         [0035]    Also, a periphery of an open portion  30   a  of the front end of the exhaust air duct  30  is reinforced by a flange portion  30   b.  This open portion  30   a  is able to be connected to the discharge flow path in an airtight manner by placing the lower side of the flange portion  30   b  close against the lower case and holding the upper side of the flange portion  30   b  down against the rear side end portion of the battery stack  22 . A side portion of the flange portion  30   b  is connected in an airtight manner to an inside wall of an upper cover that covers a side portion and an upper portion of the battery pack  20 . An airtight seal is achieved by arranging a sealant around the flange portion  30   b.    
         [0036]    A more reliable seal is achieved by providing a recessed portion that is recessed downward in two locations as shown in  FIG. 4A , on an upper edge portion of the flange portion  30   b,  and adjusting the shape of a lower surface of the rear end of the battery stack  22  accordingly. Also, having the recessed portion directly contact the lower edge portion of the flange portion gives the flange portion  30   b  sufficient strength. 
         [0037]    The front end of the supply air duct  26  is a flat open portion  26   a  that is vertically narrow and wide in the width direction, matching the shape of the upper space (i.e., the supply air flow path) of the battery pack  20 , as shown in  FIG. 4B . Also, a flange portion  26   b  is formed around the open portion  26   a,  and the periphery of this flange portion  26   b  is sealed via a sealant between the rear upper end portion of the battery stack  22  and the upper cover of the battery pack  20 . The supply air duct  26  extends toward the rear, while the width thereof gradually becomes narrower. This supply air duct  26  is connected to an air outlet  28   a  around the blower  28 . The blower  28  has a cylindrical shape and blows out air drawn in from a side intake port  28   b  in a radial direction, and blows out air from the air outlet  28   a  provided in a portion of a donut-shaped blowing chamber. 
         [0038]    The intake air duct  60  has a pipe-shape that extends from the front toward the rear, and the rear end of the intake air duct  60  is connected to the intake port  28   b  of the blower  28 , as shown in  FIG. 4C . The front end is a rectangular-shaped inlet  62 . 
         [0039]    Next, the effects of the example embodiment will be described. In this way, with this example embodiment, the battery pack  20  is housed in the battery housing space  10   c  below the seat cushion  10   a  of the rear seat  10 , so the battery will not get in the way of other equipment and vehicle space is able to be more efficiently utilized. Also, the discharge port  50   a  of the discharge duct  48  is provided right behind the back surface lower portion of the seatback  10   b  of the rear seat  10 , so the discharge duct  48  is able to be relatively short, which enables pressure loss there to be small. 
         [0040]    Furthermore, the exhaust port  32  opens into the discharge duct  48 , the discharge duct  48  discharges exhaust air from the discharge port  50   a,  and the discharge port  50   a  is pointed in a substantially horizontal direction and is covered by cloth or the like, so foreign matter is able to be prevented from getting in from the outside. In particular, the discharge port  50   a  is offset from the exhaust port  32  in the width direction, so air discharged upward from the exhaust port  32  temporarily travels in the width direction of the vehicle, and then strikes the back surface of the seatback  10   b  from the discharge port  50   a  in the front surface and escapes upward. This kind of an air path makes it possible to reliably prevent foreign matter from getting in and the like. Also, the discharge port  50   a  is provided over a relatively large area in the vehicle width direction, so pressure loss is able to be reduced with a relatively complex path. 
         [0041]    Exhaust air is discharged into the luggage space  40  from the opening between the deck board  42  and the back surface of the seatback  10   b.  Therefore, it is unlikely that this airflow will affect an occupant, so exhaust air will not cause the occupant any discomfort. 
         [0042]    Also, the inlet  62  is on a side lower portion of the rear seat, so it is less likely that the flow of intake air from here will be felt by a leg of an occupant or the like. Moreover, the inlet  62  is pointed at an angle, so the flow of intake air is not that fast. As a result, the intake air will not easily be felt by an occupant, and noise generated by the intake air is also able to be suppressed.

Technology Category: y