Patent Publication Number: US-2022227214-A1

Title: Vehicle-mounted battery pack

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Priority is claimed on Japanese Patent Application No. 2021-007447, filed Jan. 20, 2021, the content of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a vehicle-mounted battery pack. 
     Description of Related Art 
     As a vehicle-mounted battery pack, for example, a configuration in which a battery module is placed on a tray bottom plate (hereinafter, referred to as a floor part), an attachment beam (hereinafter, referred to as a frame body) is provided around the floor part, and the frame body is attached to the bottom of the vehicle is known. The floor part includes an upper plate, a middle plate, and a lower plate, and a cooling cavity is formed between the upper plate and the middle plate. Further, a buffer cavity is formed between the middle plate and the lower plate (that is, below the cooling cavity). 
     For example, a cooling pipe for cooling the battery module is disposed in the cooling cavity. The buffer cavity protects, for example, the battery module against an impact from below (see, for example, Published Japanese Translation No. 2019-531955 of the PCT International Publication). 
     SUMMARY OF THE INVENTION 
     Here, the conventional buffer cavity can protect the battery module against an impact from below. However, in the conventional buffer cavity, for example, when a load is input from the side of the vehicle body due to side collision, it is difficult to protect the battery module by absorbing the input load. Therefore, there is a possibility that the frame body is deformed inward in the vehicle width direction by the load input from the side of the vehicle body due to the side collision, and the battery module (that is, batteries) is damaged. 
     As a countermeasure, for example, it is conceivable to reinforce the floor part. However, when the floor part is reinforced, it is difficult to reduce the weight of the vehicle, and there is room for improvement from this viewpoint. 
     An aspect of the present invention provides a vehicle-mounted battery pack capable of protecting a battery, and furthermore achieving weight reduction. 
     (1) A vehicle-mounted battery pack according to one aspect of the present invention includes: a battery tray including a floor part disposed at a floor of a vehicle, and a frame body having side frames that are provided on at least left and right sides of the floor part in a vehicle width direction and that are attached to the vehicle, wherein the battery tray includes: a battery disposition region provided at a center in the vehicle width direction and on which a battery module consisted by a plurality of batteries is placed, and an impact-absorbing region provided on an outer side of the battery disposition region in the vehicle width direction, and wherein the side frame is formed to be thinner than the impact-absorbing region, and the impact-absorbing region includes an easily deformable portion, which is formed of at least one of an inclined portion and a thin portion, at a lower portion thereof. 
     According to the composition of the aspect of the above mentioned (1), the battery module is placed in the battery disposition region of the battery tray, and the impact-absorbing region is provided on an outer side of the battery disposition region in the vehicle width direction. Further, the side frames provided on the left and right sides in the vehicle width direction are formed to be thinner than the impact-absorbing region. Furthermore, the easily deformable portion is formed in a lower portion (lower surface) of the impact-absorbing region. The easily deformable portion is formed of at least one of the inclined portion and the thin portion. 
     Therefore, for example, when a load (hereinafter, sometimes referred to as a side collision load) is input from the side of the vehicle body due to the side collision, the impact energy can be favorably absorbed by deforming the impact-absorbing region downward and crushing (compressing) the side frames using the side collision load input. Furthermore, the impact-absorbing region is thicker than the side frames. Therefore, deformation of the impact-absorbing region due to the side collision load input can be minimized in a range where the battery module can be protected. 
     Thus, the battery module can be protected, it is not necessary to reinforce the vehicle pack more than necessary, and the weight of the vehicle pack can be reduced. 
     (2) In the aspect of the above mentioned (1), the side frames may have a thin portion at the center of the cross section thereof. 
     According to the composition of the aspect of the above mentioned (2), the thin portion is formed at the center of the cross section of the side frames. Therefore, the side frames can be crushed from the center of the cross section by the side collision load input by the side collision. Thus, crushing of the side frames due to the side collision load can be generated across the side frames, and the impact energy absorption effect can be enhanced. 
     (3) In the aspect of the above mentioned (1) or (2), a lower portion of the side frames may be disposed at a position lower than a lower portion of the battery disposition region in an up-down direction. 
     According to the composition of the aspect of the above mentioned (3), the lower portion of the side frames is disposed at a position lower than the lower portion of the battery disposition region in the up-down direction. Therefore, when the side frames are crushed by the side collision load input by the side collision, the impact-absorbing region can be deformed downward. Thus, when the side frames are crushed, it is possible to prevent the lower portion of the side frames from interfering with the lower portion of the impact-absorbing region. As described above, the impact-absorbing region is favorably deformed downward and the side frames are favorably crushed, so that the impact energy absorption effect can be enhanced. 
     (4) In the aspect of any one of the above mentioned (1) to (3), the lid may be fixed to an upper portion of the side frames on the battery module side, and the side frames may include a projection projecting outward from the lid in the vehicle width direction, and an outer portion of the projection may be fixed at an outer side of the vehicle in the vehicle width direction. 
     According to the constitution of the aspect of the above mentioned (4), the side frames are formed with the projection projecting outward from the lid in the vehicle width direction. The lid is fixed to an upper portion of the projection on the battery module side. Furthermore, the outer portion of the projection is fixed to the outer side of the vehicle in the vehicle width direction (for example, inner panel of side sill). Therefore, at above of the side frames, a deformation allowing space that allows crushing of the side frames (specifically, the projection) can be ensured between the upper portion and the outer portion thereof. Thus, the side frames (projection) can be favorably crushed by the side collision load input by the side collision, and the impact energy absorption effect can be enhanced. 
     (5) In the aspect of the above mentioned (4), a projecting inclined portion may be provided at an upper portion of the projection, the projecting inclined portion may be inclined upward from an outer side in the vehicle width direction toward an inner side in the vehicle width direction; and an L-shaped closed cross-section may be provided between the projecting inclined portion and the easily deformable portion, the L-shaped closed cross-section may include a vertically closed cross-section vertically erected toward the projecting inclined portion, and a horizontally closed cross-section projecting inward in the vehicle width direction from a lower portion of the vertically closed cross-section toward the easily deformable portion. 
     According to the composition of the aspect of the above mentioned (5), the projecting inclined portion is formed at the upper portion of the projection, and the easily deformable portion is formed at the lower portion of the impact-absorbing region. The projecting inclined portion and the easily deformable portion are inclined upward from the outer side in the vehicle width direction toward the inner side in the vehicle width direction. Further, the L-shaped closed cross-section is provided between the projecting inclined portion and the easily deformable portion. Furthermore, the vertically closed cross-section of the L-shaped closed cross-section is vertically erected toward the projecting inclined portion, and the horizontally closed cross-section is projected inward in the vehicle width direction from the lower portion of the vertically closed cross-section toward the easily deformable portion. 
     Therefore, for example, the side collision load input by the side collision can generate a moment that moves the top of the vertically closed cross-section of the L-shaped closed cross-section inward in the vehicle width direction and moves the inner end of the horizontally closed cross-section downward. Specifically, for example, in the side frame on the right side of the vehicle body, the clockwise moment can be generated by the side collision load input by the side collision when viewed from the front side of the vehicle body. Thus, the easily deformable portion of the impact-absorbing region can be folded downward reliably. 
     Therefore, the projection  108  and the impact-absorbing region  116  can be favorably crushed by the side collision load F input by the side collision, and the impact energy absorption effect can be enhanced. 
     (6) In the aspect of any one of the above mentioned (1) to (5), a plurality of longitudinal batteries constituting the battery module may be arranged in the battery disposition region with a longitudinal direction thereof oriented in a vehicle front-rear direction, the vehicle-mounted battery pack may include a lower cross member that extends in the vehicle width direction at below the plurality of batteries placed in the battery disposition region and at a center of the battery tray in a front-rear direction of a vehicle body, and that is attached to the battery tray; and an upper cross member that extends in the vehicle width direction at above the lower cross member and at above the plurality of batteries, and by the upper cross member and the lower cross member, among the plurality of batteries arranged in the vehicle front-rear direction, ends of the plurality of batteries at a center side in the front-rear direction of the vehicle body may be fixed to the battery tray. 
     According to the composition of the aspect of the above mentioned (6), the plurality of longitudinal batteries constituting the battery module is arranged in the vehicle front-rear direction. Further, the lower cross member is provided below the battery module, and the upper cross member is provided above the battery module. Furthermore, among the plurality of batteries arranged in the vehicle front-rear direction, the ends of the plurality of batteries at the center side in the front-rear direction of the vehicle body are fixed to the battery tray by the lower cross member and the upper cross member. Thus, the plurality of batteries (that is, the battery module) can be stably fixed to the battery disposition region by the lower cross member and the upper cross member. 
     Further, the longitudinal batteries are arranged in the vehicle front-rear direction, and the lower cross member and the upper cross member are provided below and above the battery module, respectively. Therefore, the width of the battery module (that is, the battery disposition region) in the vehicle width direction can be suppressed to be narrow. Thus, a space (space) for forming the impact-absorbing region can be ensured between the battery disposition region and the side frames. Therefore, for example, the impact-absorbing region can be suitably deformed by the side collision load input by the side collision, and the battery module can be protected from the side collision load by the impact-absorbing region. 
     According to an aspect of the present invention, the side frames provided on the left and right sides in the vehicle width direction are formed to be thinner than the impact-absorbing region. Furthermore, the easily deformable portion is formed in a lower portion (lower surface) of the impact-absorbing region. Thus, the battery can be protected, and furthermore the weight can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a vehicle including a vehicle-mounted battery pack of one embodiment according to the present invention; 
         FIG. 2  is a bottom view of a vehicle including the vehicle-mounted battery pack of one embodiment; 
         FIG. 3  is a perspective view of a vehicle including the vehicle-mounted battery pack of one embodiment broken at an upper cross member and a lower cross member; 
         FIG. 4  is an exploded perspective view of a battery case of one embodiment in which a case cover is removed from a case body; 
         FIG. 5  is a cross-sectional view of the vehicle-mounted battery pack of one embodiment; 
         FIG. 6  is a perspective view illustrating a case body of one embodiment; 
         FIG. 7  is a cross-sectional view illustrating a cooling passage of the vehicle-mounted battery pack of one embodiment; 
         FIG. 8  is an enlarged cross-sectional view of a portion VIII in  FIG. 5 ; 
         FIG. 9  is a cross-sectional view taken along line IX-IX of  FIG. 1 ; 
         FIG. 10  is an exploded perspective view of an auxiliary battery disassembled from the case body of one embodiment; 
         FIG. 11  is a cross-sectional view of the vehicle of  FIG. 1  taken along line XI-XI; and 
         FIG. 12  is a cross-sectional view for explaining an example in which impact energy is absorbed by a right frame in the case body of one embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, a vehicle-mounted battery pack according to one embodiment of the present invention will be described with reference to the drawings. In the drawings, an arrow FR indicates the front of the vehicle, an arrow UP indicates the upper side of the vehicle, and an arrow LH indicates the left side of the vehicle. Note that the use, type, and the like of the vehicle are not particularly limited, but an automobile will be described as an example as one embodiment. Further, the vehicle has a substantially bilaterally symmetrical constitution. Therefore, the left and right components will be described below with the same reference numbers. 
     &lt;Vehicle&gt; 
     As illustrated in  FIGS. 1 and 2 , a vehicle Ve includes a vehicle main body (hereinafter, sometimes referred to as a vehicle body  10 )  10  and a vehicle-mounted battery pack  20 . Hereinafter, the vehicle-mounted battery pack  20  may be simply referred to as a “battery pack  20 ”. 
     &lt;Vehicle Main Body&gt; 
     The vehicle main body  10  includes a side sill unit  22 , a floor panel  23 , a floor tunnel  24 , a front side frame unit  25 , a rear frame unit  26 , a floor cross member unit  27 , and a floor vertical frame unit  28 . 
     The side sill unit  22  includes a right side sill  31  and a left side sill  31 . The right side sill  31  is formed in a closed cross section and is a member having high rigidity constituting a part of the framework of the vehicle body  10 . The right side sill  31  is provided on a right outer side in the vehicle width direction, and extends in a front-rear direction of the vehicle body along a right outer portion of the floor panel  23  in the vehicle width direction. 
     The left side sill  31  is formed in a closed cross section and is a member having high rigidity constituting a part of the framework of the vehicle body  10 . The left side sill  31  is provided on a left outer side in the vehicle width direction, and extends in the front-rear direction of the vehicle body along a left outer portion of the floor panel  23  in the vehicle width direction. 
     The floor panel  23  is provided between the left side sill  31  and the right side sill  31 . The floor panel  23  is a plate-shaped member having a substantially rectangular shape in plan view, and forms the floor part of the vehicle Ve. The floor tunnel  24  extends in the front-rear direction of the vehicle body at the center of the floor panel  23  in the vehicle width direction. The floor tunnel  24  is raised upward from the floor panel  23 . 
     The front side frame unit  25  includes a right front side frame  36  and a left front side frame  36 . The right front side frame  36  and the left front side frame  36  are provided on the front side of the vehicle body with respect to the battery pack  20 . 
     The rear frame unit  26  includes a right rear frame  41  and a left rear frame  41 . The right rear frame  41  and the left rear frame  41  are provided on the rear side of the vehicle body with respect to the battery pack  20 . 
     The floor cross member unit  27  is disposed between the right side sill  31  and the left side sill  31 , and is joined along an upper surface of the floor panel  23 . 
     The floor cross member unit  27  includes a right first floor cross member  44 , a left first floor cross member  44 , a right second floor cross member  45 , a left second floor cross member  45 , a right third floor cross member  46 , a left third floor cross member  46 , and a fourth floor cross member  47 . 
     The floor tunnel  24  crosses (in the embodiment, orthogonal to) the left and right first floor cross members  44 , the left and right second floor cross members  45 , and the left and right third floor cross members  46 , and extends in the front-rear direction of the vehicle body. 
     As illustrated in  FIGS. 1 and 3 , the floor vertical frame unit  28  includes a plurality of first to fourth floor vertical frames  55  to  58  on the floor panel  23  at intervals in the vehicle width direction. Specifically, the first floor vertical frame  55  and the second floor vertical frame  56  are provided on the right side of the floor tunnel  24  on the floor panel  23  at an interval in the vehicle width direction. The third floor vertical frame  57  and the fourth floor vertical frame  58  are provided on the left side of the floor tunnel  24  on the floor panel  23  at an interval in the vehicle width direction. The battery pack  20  is provided below the floor panel  23 . 
     &lt;Battery Pack&gt; 
     The battery pack  20  is provided below the floor panel  23  (that is, under the floor part of the vehicle Ve). Furthermore, the battery pack  20  is disposed below the left and right second floor cross members  45 , the left and right third floor cross members  46 , and the first to fourth floor vertical frames  55  to  58 . As illustrated in  FIG. 4 , the battery pack  20  includes a battery case  61 , a battery module  62 , and an auxiliary battery  63 . 
     (Battery Case) 
     As illustrated in  FIGS. 4 to 6 , the battery case  61  includes a case body  65  and a case cover (lid)  66 . The case body  65  includes a battery tray  71 , a lower cross member  72 , an upper cross member  73 , and an upper deck  74 . The battery tray  71  includes a floor part  76  and a frame body  77 . 
     The floor part  76  is formed in, for example, a rectangular shape in plan view, and is provided under the floor of the vehicle Ve (see  FIG. 1 ) and below the battery module  62  so that the battery module  62  can be placed. In the floor part  76 , for example, a front surface  76   a  on which the battery module  62  is placed is formed flat, and a back surface  76   b  opposite to the front surface  76   a  is also formed flat. 
     As illustrated in  FIGS. 5, 7, and 8 , a plurality of (eight in the embodiment) first hollow chambers (hollow chambers)  81  and a plurality of (three in the embodiment) second hollow chambers (other hollow chambers)  82  are integrally formed with the floor part  76  in the floor part  76  between the front surface  76   a  and the back surface  76   b.    
     The plurality of first hollow chambers  81  extends in the front-rear direction of the vehicle body inside the floor part  76 . The plurality of first hollow chambers  81  is provided at a plurality of places inside the floor part  76  in a state where a pair of first hollow chambers  81  is put together to be adjacent in the vehicle width direction. The pairs of first hollow chambers  81  put together are provided at two places on the floor part  76  near the center in the vehicle width direction and two places on the left and right sides in the vehicle width direction at intervals in the vehicle width direction. 
     Note that in the first hollow chamber  81 , for example, a partition wall  83  is formed at the center in the vehicle width direction in order to ensure the strength and rigidity of the floor part  76 . 
     As illustrated in  FIGS. 5 and 6 , in the pair of first hollow chambers  81 , for example, at a rear end  76   c  of the floor part  76 , a rear end  81   a  of one first hollow chamber  81  communicates with a rear end  81   a  of the other first hollow chamber  81 . Further, in the pair of first hollow chambers  81 , for example, at a front end  76   d  of the floor part  76 , an opening is formed in a front end  81   b  of one first hollow chamber  81 , and an opening is formed in a front end  81   b  (see also  FIG. 7 ) of the other first hollow chamber  81 . That is, the pair of first hollow chambers  81  is formed in a U shape in plan view. 
     A cooling passage (cooling water path)  85  is formed in a U shape (including a substantially U shape) in plan view by the pair of first hollow chambers  81 . That is, a plurality of (four in the embodiment) cooling passages is formed by the plurality of first hollow chambers  81  (eight in the embodiment). Thus, the cooling passages  85  integrally extend in the front-rear direction of the vehicle body inside the floor part  76 . Note that it is sufficient if at least one cooling passage  85  is provided, and the number of cooling passages  85  can be arbitrarily selected. 
     In the cooling passage  85 , a water supply connector (cooling water connector)  86  (see also  FIG. 7 ) for supplying water communicates with the opening (water supply port) of one first hollow chamber  81  at the front end  76   d  of the floor part  76 . Further, a water drain connector (cooling water connector)  87  (see also  FIG. 7 ) for draining water communicates with the opening (water drain port) of the other first hollow chamber  81  at the front end  76   d  of the floor part  76 . 
     Therefore, for example, cooling water cooled by a radiator (not illustrated) of the vehicle Ve (see  FIG. 1 ) can be guided from the water supply connector  86  to the one cooling passage  85  as indicated by an arrow, and can be guided from a rear end  85   a  of one cooling passage  85  to a rear end  85   a  of the other cooling passage  85  as indicated by an arrow. Further, the cooling water guided to the rear end  85   a  of the other cooling passage  85  can be guided to the water drain connector  87  via the other cooling passage  85  as indicated by an arrow. Furthermore, the cooling water guided to the water drain connector  87  can be returned from the water drain connector  87  to the radiator. Thus, the battery module  62  can be cooled by the cooling water guided to the cooling passage  85 . That is, the floor part  76  also serves as a water jacket of the battery pack  20 . 
     As illustrated in  FIGS. 5 and 8 , the second hollow chamber  82  is integrally formed inside the floor part  76 . The second hollow chamber  82  is formed in a state of being isolated (partitioned) in the vehicle width direction from the first hollow chamber  81  forming the cooling passage  85 . The second hollow chamber  82  extends in the vehicle front-rear direction at the center of the floor part  76  in the vehicle width direction and between the pair of cooling passages  85 . Further, the second hollow chamber  82  extends in the vehicle front-rear direction on the left side of the floor part  76  in the vehicle width direction and between the pair of cooling passages  85 . Furthermore, the second hollow chamber  82  extends in the vehicle front-rear direction on the right side of the floor part  76  in the vehicle width direction and between the pair of cooling passages  85 . Note that in the second hollow chamber  82 , for example, a partition wall  84  is formed at the center in the vehicle width direction in order to ensure the strength and rigidity of the floor part  76 . 
     A plurality of (three in the embodiment) cavities  88  is formed by the plurality of second hollow chambers  82 . The number of cavities  88  can be arbitrarily selected. By forming the plurality of cavities  88  in the floor part  76 , a cooling region  91  formed by the cooling passages  85  and a cavity region  92  formed by the cavities  88  are provided in the floor part  76 . The cooling region  91  and the cavity region  92  are alternately disposed in the vehicle width direction. Therefore, a battery disposition region  115  (that is, the battery module  62 ) to be described below can be efficiently cooled by the cooling region  91 . The frame body  77  is provided around the floor part  76 . 
     As illustrated in  FIG. 6 , the frame body  77  includes a front frame (front-side frame)  94 , a rear frame (rear-side frame)  95 , a right frame (side frame)  96 , a left frame (side frame)  97 , a right inclined frame  98 , and a left inclined frame  99 . 
     As illustrated in  FIGS. 2 and 6 , the front frame  94  is provided at a front end (vehicle body front side)  76   d  of the floor part  76  in the front-rear direction of the vehicle body. On the front frame  94 , a right front support bracket  102  and a left front support bracket  102  protrude toward the front of the vehicle body. The right front support bracket  102  is attached to a right branch (bottom of the vehicle)  38  extending from a rear portion  36   a  of the right front side frame  36 . The left front support bracket  102  is attached to a left branch (bottom of the vehicle)  38  extending from a rear portion  36   a  of the left front side frame  36 . That is, the front frame  94  is attached to the right branch  38  and the left branch  38 . 
     The rear frame  95  is provided at a rear end (vehicle body rear side)  76   c  of the floor part  76  in the front-rear direction of the vehicle body. On the rear frame  95 , a right rear support bracket  104  and a left rear support bracket  104  protrude toward the rear of the vehicle body. The right rear support bracket  104  is attached to the fourth floor cross member (the bottom of the vehicle)  47  via a right coupling bracket  105  (see also  FIG. 5 ). The left rear support bracket  104  is attached to the fourth floor cross member  47  via a left coupling bracket  105 . That is, the rear frame  95  is attached to the fourth floor cross member  47 . 
     As illustrated in  FIGS. 6, 8, and 9 , the right frame  96  is provided along a right side portion (right side)  76   e  of the floor part  76  in the vehicle width direction. For example, the right frame  96  is attached to a bottom (bottom of the vehicle)  32   a  of an inner panel  32  of the right side sill  31  by a fastening bolt  33  from below. Note that the right frame  96  will be described below in detail. 
     As illustrated in  FIGS. 2, 5, and 6 , the left frame  97  is provided along a left side portion (left side)  76   f  of the floor part  76  in the vehicle width direction. The left frame  97  is attached to a bottom (bottom of the vehicle)  32   a  of an inner panel  32  of the left side sill  31  from below. The right inclined frame  98  is coupled in an inclined manner to a rear end of the right frame  96  and a right end of the rear frame  95 . The left inclined frame  99  is coupled in an inclined manner to a rear end of the left frame  97  and a left end of the rear frame  95 . 
     The frame body  77  is formed in a rectangular frame shape (including a substantially rectangular frame shape) in plan view by the front frame  94 , the rear frame  95 , the left frame  97 , the right frame  96 , the right inclined frame  98 , and the left inclined frame  99 . The case cover  66  (see also  FIG. 4 ) is attached to the frame body  77 . 
     As illustrated in  FIGS. 8 and 9 , the right frame  96  includes a frame floor  107  and a projection (extension)  108 . The frame floor  107  is provided along the right side portion  76   e  of the floor part  76 , and is provided between the right side portion  76   e  of the floor part  76  and a right wall  66   a  of the case cover  66 . A front surface  107   a  of the frame floor  107  is formed to be flush with the front surface  76   a  of the floor part  76 . 
     The projection  108  projects outward in the vehicle width direction (that is, the right side sill  31  side) from the right wall  66   a  of the case cover  66 . The projection  108  includes a cover attachment portion (upper portion)  108   a , a side sill attachment portion (outer portion)  108   b , and a projecting inclined portion  108   d.    
     The cover attachment portion  108   a  is formed at an upper portion of the projection  108  on the battery module side. An attachment portion  67  (see also  FIG. 7 ) of the case cover  66  is fixed to the cover attachment portion  108   a  from above by a fastening bolt  111 . 
     The side sill attachment portion  108   b  is formed at an outer portion of the projection  108  on the side sill  31  side. The side sill attachment portion  108   b  is fixed to a bottom  32   a  of an inner panel (inner side of the vehicle in the vehicle width direction)  32  of the right side sill  31  from below by the fastening bolt  33 . 
     The projecting inclined portion  108   d  is formed, for example, between the side sill attachment portion  108   b  and the cover attachment portion  108   a  in the upper portion of the projection  108 . For example, the projecting inclined portion  108   d  is inclined upward from the outer side in the vehicle width direction (that is, the side sill attachment portion  108   b  side) toward the inner side in the vehicle width direction (the cover attachment portion  108   a  side). 
     A plurality of (multiple) frame hollow chambers (hollow chambers)  112  is integrally formed by a partition wall  113  inside the right frame  96 . The plurality of frame hollow chambers  112  extends in the front-rear direction of the vehicle body inside the right frame  96 . 
     The right frame  96  has, for example, a thin portion  113   a  at the center of the cross section of the projection  108 . The thin portion  113   a  is positioned at the center of the cross section of the projection  108  of the partition wall  113  and is formed horizontally in the vehicle width direction. 
     Further, the right frame  96 , in particular, a lower portion (lower surface, lower portion of the side frame)  108   c  of the projection  108 , is disposed at a position lower than a lower portion (lower surface)  115   a  of the battery disposition region  115  in an up-down direction. 
     As illustrated in  FIGS. 5 and 6 , the left frame  97  is formed substantially bilaterally symmetric with the right frame  96 . Therefore, hereinafter, each portion forming the left frame  97  is denoted by the same reference numbers as that of the right frame  96 , and a detailed description thereof is omitted. 
     Here, in the battery tray  71 , a tray floor  75  is formed by the floor part  76 , the frame floor  107  of the right frame  96 , and the frame floor  107  of the left frame  97 . The tray floor  75  includes the battery disposition region  115 , a right impact-absorbing region (impact-absorbing region)  116 , and a left impact-absorbing region (impact-absorbing region)  116 . 
     The battery disposition region  115  is positioned at the center in the vehicle width direction, in which the entire battery module  62  is placed. The plurality of (multiple) first hollow chambers  81  (that is, the cooling passages  85 ) and the plurality of (multiple) second hollow chambers  82  (that is, the cavities  88 ) are integrally formed inside the battery disposition region  115 . 
     As illustrated in  FIGS. 8 and 9 , the right impact-absorbing region  116  is positioned between the battery disposition region  115  and the right wall  66   a  (that is, the projection  108 ) of the case cover  66  on an outer side of the battery disposition region  115  in the vehicle width direction. The plurality of frame hollow chambers  112  (that is, cavities) is integrally formed inside the right impact-absorbing region  116 . 
     Further, the projection  108  is formed such that the wall thickness of the partition wall  113  forming the frame hollow chambers  112  is thinner than that of the right impact-absorbing region  116 . Furthermore, the impact-absorbing region  116  includes, for example, an easily deformable portion  118  in a lower portion  116   a . The easily deformable portion  118  is formed of, for example, an inclined portion inclined upward from the outer side in the vehicle width direction (that is, the lower portion  108   c  side of the projection  108 ) toward the inner side in the vehicle width direction. 
     Note that, in the embodiment, an example in which the easily deformable portion  118  is formed of the inclined portion will be described, but it is not limited thereto. As another example, for example, the partition wall  113  corresponding to the easily deformable portion  118  may have a thin portion that is thinner than that of the other partition walls  113  to form the easily deformable portion  118 . Alternatively, the inclined portion of the embodiment forming the easily deformable portion  118  may be thinner than the wall thickness of the other partition walls  113 . 
     Further, the right frame  96  has a closed cross-section  109  having an L-shape between the projecting inclined portion  108   d  and the easily deformable portion  118 . The closed cross-section  109  having an L-shape includes a vertically closed cross-section  109   a  and a horizontally closed cross-section  109   b . Hereinafter, the closed cross-section  109  having an L-shape may be referred to as an “L-shaped closed cross-section  109 ”. 
     The vertically closed cross-section  109   a  is vertically erected from the lower portion  108   c  of the projection  108  toward the cover attachment portion  108   a  (that is, the top). The cover attachment portion  108   a  is located at an inner end of the projecting inclined portion  108   d.    
     The horizontally closed cross-section  109   b  protrudes inward in the vehicle width direction from a lower portion (that is, the lower portion  108   c  of the projection  108 ) of the vertically closed cross-section  109   a  toward the easily deformable portion  118 . An inner end  109   c  of the horizontally closed cross-section  109   b  is located at an outer end of the easily deformable portion  118 . 
     As illustrated in  FIGS. 5 and 6 , the left impact-absorbing region  116  is formed substantially bilaterally symmetric with the right impact-absorbing region  116 . Therefore, a detailed description of the left impact-absorbing region  116  is omitted. Note that, hereinafter, the right impact-absorbing region  116  may be abbreviated as an “impact-absorbing region  116 ”. 
     The tray floor  75  is provided with the lower cross member  72 . The lower cross member  72  extends in the vehicle width direction at the center (middle) of the tray floor  75  in the front-rear direction of the vehicle body and below the battery module  62  (plurality of batteries  123 ). The lower cross member  72  is attached to the tray floor  75  from above, for example, by a fastening bolt  127  (described below in  FIG. 11 ). In this state, the lower cross member  72  is coupled to the right frame  96  and the left frame  97 . The lower cross member  72  will be described in detail below. 
     In the battery disposition region  115  of the tray floor  75 , a driving battery module  62  (see  FIG. 4 ) is placed in a front region on the vehicle body front side of the lower cross member  72  and in a rear region on the vehicle body rear side of the lower cross member  72 . 
     (Battery Module) 
     As illustrated in  FIGS. 4 to 6 , the battery module  62  includes, for example, a first module  121  placed in a front region of the battery disposition region  115  and a second module  122  placed in a rear region of the battery disposition region  115 . 
     In the first module  121 , a plurality of batteries  123  is arranged in the vehicle width direction in the front region. The batteries  123  are formed, for example, in a longitudinally rectangular shape with a plurality of battery cells (not illustrated) being stacked in a longitudinal direction. Hereinafter, the batteries  123  that are longitudinally long may be referred to as “longitudinal batteries  123 ”. Further, disposing the longitudinal batteries  123  longitudinally means disposing the batteries  123  with a longitudinal direction oriented in the front-rear direction of the vehicle body. 
     That is, the first module  121  is arranged in the vehicle width direction in the front region of the battery disposition region  115  in a state where the plurality of longitudinal batteries  123  is disposed longitudinally. Further, the second module  122  is arranged in the vehicle width direction in the rear region of the battery disposition region  115  in a state where the plurality of longitudinal batteries  123  is disposed longitudinally. 
     Thus, the lower cross member  72  is disposed between the first module  121  and the second module  122  in the front-rear direction of the vehicle body. 
     In the embodiment, an example in which a pair of the first module  121  and the second module  122  is disposed in the front-rear direction of the vehicle body has been described, but it is not limited thereto. As another example, for example, three or more rows of the first module  121  and the second module  122  may be disposed in the front-rear direction of the vehicle body. 
     As illustrated in  FIGS. 3, 10, and 11 , the upper cross member  73  is provided between the first module  121  and the second module  122  and above the battery module  62  (plurality of batteries  123 ). The upper cross member  73  extends in the vehicle width direction along the lower cross member  72  above the lower cross member  72 . 
     The upper cross member  73  is placed on an upper end  124   a  of an upper and lower coupling collar  124  and a step  123   a  of the battery  123 . A lower end  124   b  of the upper and lower coupling collar  124  is coupled to the lower cross member  72 . 
     In this state, the fastening bolt (fastening member)  127  penetrates a flange  73   a  of the upper cross member  73 , the battery  123 , an attachment portion  72   a  of the lower cross member  72 , and an upper portion of the tray floor  75  from above. A threaded portion  127   a  of the penetrating fastening bolt  127  protrudes into the cavity  88  and is fastened to a fastening nut  129 . Note that, in the embodiment, the fastening bolt  127  is exemplified as the fastening member, but it is not limited thereto. As another example, for example, a rivet or the like may be used as the fastening member. 
     Thus, the lower cross member  72  is fixed (attached) to the tray floor  75  in the cavity  88  by the fastening bolt  127  and the fastening nut  129 . Further, the lower cross member  72  is fastened to the plurality of batteries  123  (that is, the battery module  62 ) by the fastening bolts  127  and the fastening nuts  129  in the cavities  88 . Furthermore, the upper cross member  73  is coupled to the lower cross member  72  and the tray floor  75  by a fastening bolt  125 , the upper and lower coupling collar  124 , and the fastening nut  129 . 
     In addition, the plurality of batteries  123  (battery module  62 ) is sandwiched in the up-down direction between the upper cross member  73  and the attachment portions  72   a  of the lower cross member  72  in the cavities  88 . In this state, the plurality of batteries  123  is fastened to the tray floor  75  by the fastening bolts  127  and the fastening nuts  129 . Thus, the plurality of batteries  123  is fixed from above by the upper cross member  73 . That is, the upper cross member  73  fixes the plurality of batteries  123  disposed in the front-rear direction of the vehicle body from above and fixes the plurality of batteries  123  disposed in the vehicle width direction from above at the center of the battery module  62  in the front-rear direction of the vehicle body. 
     In other words, among the plurality of longitudinal batteries  123  arranged in the vehicle front-rear direction, the ends on the center side in the front-rear direction of the vehicle body are fixed to the battery tray  71  by the lower cross member  72  and the upper cross member  73 . 
     Further, the plurality of batteries  123  disposed in the vehicle width direction is coupled to each other at a front end  62   a  of the battery module  62  by front coupling brackets  131 . Furthermore, the plurality of batteries  123  disposed in the vehicle width direction is coupled to each other at a rear end  62   b  of the battery module  62  by rear coupling brackets (not illustrated). 
     Thus, the plurality of batteries  123  (that is, the battery module  62 ) is placed in the battery disposition region  115 , and the battery module  62  is fixed from above by the upper cross member  73  at the center in the front-rear direction of the vehicle body (see also  FIG. 4 ). Thus, the battery module  62  (that is, the plurality of longitudinal batteries  123 ) is stably fixed, and in addition, is integrally coupled in a state where rigidity of the battery module  62  is ensured. 
     (Auxiliary Battery) 
     As illustrated in  FIGS. 4 and 10 , the upper deck  74  is provided at the center in the vehicle width direction at above the battery module  62 . 
     The upper deck  74  is formed in a band shape and extends in the front-rear direction of the vehicle body from the front end  62   a  to the rear end  62   b  of the battery module  62 . The upper deck  74  is provided with an auxiliary battery  63  such as a high-voltage junction board and an electronic control unit (controller, ECU). 
     A high-voltage junction box is, for example, an auxiliary device that supplies electricity of the driving battery module  62  to a driving motor (not illustrated). The ECU is, for example, a battery management unit that controls discharge and charge between the driving battery module  62  and the driving motor. 
     As illustrated in  FIGS. 4, 6, and 8 , the battery module  62 , the auxiliary battery  63 , and the like are accommodated (disposed) in the case body  65 . In this state, the case cover  66  is attached to the frame body  77  by the fastening bolt  111  from above via a sealing member  135 . 
     Thus, the inside of the battery case  61  is formed to be a sealed space by the battery tray  71  and the case cover  66 . The battery module  62  is housed in the sealed space of the battery case  61  (see also  FIG. 5 ). 
     Further, in the case cover  66 , a raised portion  68  extends in the front-rear direction of the vehicle body along the upper deck  74  at the center in the vehicle width direction. The upper deck  74 , the auxiliary battery  63 , and the like are housed in the raised portion  68  from below. In this state, the battery pack  20  is assembled and attached under the floor of the vehicle Ve (see  FIG. 1 ). 
     (Assembly of the Battery Pack  20  Under the Floor of the Vehicle) 
     As illustrated in  FIGS. 2, 3, and 6 , the right frame  96  of the battery pack  20  is fixed to the inner panel  32  of the right side sill  31  from below. The left frame  97  is fixed to the inner panel  32  of the left side sill  31  from below. 
     The front frame  94  is fixed to the right branch  38  and the left branch  38  via the right front support bracket  102  and the left front support bracket  102 . The rear frame  95  is fixed to the fourth floor cross member  47  via the right rear support bracket  104 , the right coupling bracket  105 , the left rear support bracket  104 , and the left coupling bracket  105 . 
     As illustrated in  FIGS. 3 and 11 , a head  125   a  of the fastening bolt  125  passes through a through-hole  141  of the case cover  66  and is in contact with the floor panel  23  at above. Further, a rubber member  142  provided on the head  125   a  passes through the through-hole  141  of the case cover  66  and is in contact with the floor panel  23  at above. 
     A female screw  144  of the head  125   a  is disposed below in line with an attachment hole  145  of the floor panel  23 . A fastening bolt  146  is screwed to the female screw  144  of the head  125   a  through the attachment hole  145  of the floor panel  23 . A head  146   a  of the fastening bolt  146  protrudes upward from through-holes  55   a  to  58   a  at the top of the first to fourth floor vertical frames  55  to  58 . 
     Here, left and right flanges of the first to fourth floor vertical frames  55  to  58  are joined to the floor panel  23 . Thus, the upper cross member  73  and the lower cross member  72  of the battery pack  20  are fixed to the first to fourth floor vertical frames  55  to  58  via the floor panel  23 . Therefore, the battery pack  20  is assembled under the floor of the vehicle Ve in a state of being stably fixed below the floor panel  23 . 
     As described above, with the vehicle-mounted battery pack  20  according to the embodiment, the following operation and effect can be obtained. 
     That is, as illustrated in  FIGS. 6, 8, and 9 , in the battery tray  71 , the impact-absorbing region  116  is provided on an outer side of the battery disposition region  115  in the vehicle width direction. Therefore, for example, when a load F (hereinafter, sometimes referred to as side collision load F) is input from the side of the vehicle body due to the side collision, the side collision load F can be absorbed by the impact-absorbing region  116  to protect the battery module  62 . Thus, for example, it is not necessary to reinforce the outer portion of the vehicle Ve (specifically, the side sill  31 ) more than necessary, and the weight of the vehicle Ve can be reduced. 
     Furthermore, since the floor part  76  (specifically, the battery disposition region  115 ) also serves as a water jacket, the floor part  76  and the cooling passage  85  can be integrally molded (formed). Thus, the weight and cost of the battery pack  20  can be reduced. 
     Further, the right frame  96  (specifically, the projection  108 ) is formed to be thinner than the impact-absorbing region  116 , and an inclined portion is formed as the easily deformable portion  118  in the lower portion  116   a  of the impact-absorbing region  116 . Therefore, the impact energy can be favorably absorbed by deforming the impact-absorbing region  116  downward and crushing (compressing) the right projection  108  using the side collision load F input by the side collision. 
     Thus, it is possible to reduce the weight of the right projection  108  and the impact-absorbing region  116  (that is, the battery pack  20 ), and furthermore it is possible to enhance the impact energy absorption effect. 
     Furthermore, for example, by ensuring the wall thickness of the impact-absorbing region  116 , the deformation of the impact-absorbing region  116  can be suitably suppressed to be small. Thus, it is possible to favorably ensure protection of the battery module  62  against the side collision load F input by the side collision. 
     Thus, the battery module  62  can be protected by the right frame  96  (specifically, the projection  108 ) and the impact-absorbing region  116 , it is not necessary to reinforce the vehicle pack more than necessary, and the weight of the vehicle pack can be reduced. 
     In addition, in the right frame  96 , the thin portion  113   a  is formed at the center of the cross section of the projection  108 . Therefore, the projection  108  can be crushed from the center of the cross section by the side collision load F input by the side collision. Thus, crushing of the projection  108  due to the side collision load F can be generated across the projection  108 , and the impact energy absorption effect can be enhanced. 
     As illustrated in  FIGS. 4, 9, and 12 , in the right frame  96 , in particular, the lower portion (lower surface)  108   c  of the projection  108  is disposed at a position lower than the lower portion (lower surface)  115   a  of the battery disposition region  115  in the up-down direction. Therefore, when the projection  108  of the right frame  96  is crushed by the side collision load F input by the side collision, the impact-absorbing region  116  can be deformed downward. 
     Accordingly, when the projection  108  of the right frame  96  is crushed, in particular, the lower portion  116   a  of the impact-absorbing region  116  can be prevented from interfering with the lower portion  115   a  of the battery disposition region  115 . As described above, the impact-absorbing region  116  is favorably deformed downward, and the projection  108  is favorably crushed, so that the impact energy absorption effect can be enhanced. 
     Further, the case cover  66  is fixed to the cover attachment portion  108   a  on the battery module  62  side of the projection  108  of the right frame  96 . Furthermore, the side sill attachment portion  108   b  of the projection  108  is fixed to the bottom  32   a  of the inner panel  32  of the side sill  31 . Therefore, above the right frame  96  (specifically, the projection  108 ), a deformation allowing space  152  that allows crushing of the projection  108  can be ensured between the cover attachment portion  108   a  and the side sill attachment portion  108   b . Thus, the projection  108  can be favorably crushed by the side collision load F input by the side collision, and the impact energy absorption effect can be enhanced. 
     Further, as illustrated in  FIGS. 3 to 5 , the battery module  62  is placed in the battery disposition region  115  of the battery tray  71 , and the cooling passages  85  are extended in the front-rear direction of the vehicle body inside the battery disposition region  115 . Thus, the battery disposition region  115  (floor part  76 ) also serves as a water jacket of the battery pack  20 . Thus, for example, the water supply connector  86  and the water drain connector  87  that allow the cooling passage to communicate with a cooling radiator (not illustrated) can be disposed on a vehicle body front side of the battery module  62 . Therefore, the water supply connector  86 , the water drain connector  87 , and the cooling passage  85  (for example, the cooling pipe) can be prevented from protruding outward in the vehicle width direction of the battery module  62 . 
     Thus, at above the projection  108 , the water supply connector  86 , the water drain connector  87 , and the cooling passage  85  (see  FIG. 7 ) can be removed from the deformation allowing space  152  (see  FIG. 9 ) between the cover attachment portion  108   a  and the side sill attachment portion  108   b . Thus, when the right frame  96  (particularly, the projection) is crushed by the side collision load F, damage to the water supply connector  86 , the water drain connector  87 , and the cooling passage  85  can be suppressed, and water leakage from the water supply connector  86 , the water drain connector  87 , and the cooling passage  85  (see  FIG. 7 ) can be suppressed. 
     Furthermore, as illustrated in  FIGS. 9 and 12 , the projecting inclined portion  108   d  is formed in the upper portion of the projection  108 , and the easily deformable portion  118  (inclined portion in the embodiment) is formed in the lower portion  115   a  of the impact-absorbing region  116 . The projecting inclined portion  108   d  and the inclined portion of the easily deformable portion  118  are inclined upward from the outer side in the vehicle width direction toward the inner side in the vehicle width direction. Further, the L-shaped closed cross-section  109  is provided between the projecting inclined portion  108   d  and the easily deformable portion  118 . 
     Furthermore, the vertically closed cross-section  109   a  of the L-shaped closed cross-section  109  is vertically erected toward the inner end (that is, the cover attachment portion  108   a ) of the projecting inclined portion  108   d . Further, the horizontally closed cross-section  109   b  of the L-shaped closed cross-section  109  protrudes inward in the vehicle width direction from the lower portion (that is, the lower portion  108   c  of the projection  108 ) of the vertically closed cross-section  109   a  toward the easily deformable portion  118 . 
     Therefore, for example, moment M can be generated in the L-shaped closed cross-section  109  by the side collision load F input by the side collision. The moment M moves the top (that is, the cover attachment portion  108   a ) of the vertically closed cross-section  109   a  of the L-shaped closed cross-section  109  inward in the vehicle width direction, and moves the inner end  109   c  of the horizontally closed cross-section  109   b  downward. 
     Specifically, for example, in the right frame  96  on the right side of the vehicle body, the clockwise moment M can be generated in the L-shaped closed cross-section  109  by the side collision load F input by the side collision when viewed from the front side of the vehicle body. Thus, the easily deformable portion  118  of the impact-absorbing region  116  can be folded downward reliably. Therefore, the projection  108  and the impact-absorbing region  116  can be favorably crushed by the side collision load F input by the side collision, and the impact energy absorption effect can be enhanced. 
     In addition, as illustrated in  FIGS. 3, 4, and 11 , the plurality of longitudinal batteries  123  constituting the battery module  62  is arranged in the vehicle front-rear direction. Further, the lower cross member  72  is provided below the battery module  62 , and the upper cross member  73  is provided above the battery module  62 . Furthermore, among the plurality of longitudinal batteries  123  arranged in the vehicle front-rear direction, the ends on the center side in the front-rear direction of the vehicle body are fixed to the battery tray  71  by the lower cross member  72  and the upper cross member  73 . Thus, the plurality of longitudinal batteries  123  (that is, the battery module  62 ) can be stably fixed to the battery disposition region  115  by the lower cross member  72  and the upper cross member  73 . 
     Furthermore, the longitudinal batteries  123  are arranged in the vehicle front-rear direction, and the lower cross member  72  and the upper cross member  73  are provided below and above the battery module  62 , respectively. Therefore, the width of the battery module  62  (that is, the battery disposition region  115 ) in the vehicle width direction can be suppressed to be narrow. Thus, a space for forming the impact-absorbing region  116  can be ensured between the battery disposition region  115  and the projection  108  (see also  FIG. 8 ) of the right frame  96 . Therefore, for example, the impact-absorbing region  116  can be suitably deformed by the side collision load F input by the side collision, and the battery module  62  can be protected from the side collision load F by the impact-absorbing region  116 . 
     Note that the technical scope of the present invention is not limited to the above embodiment, and various changes can be made without departing from the scope of the present invention. 
     Moreover, it is possible to appropriately replace the constituent elements in the embodiment with well-known constituent elements without departing from the scope of the present invention, and the above-described modifications may be appropriately combined. 
     While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims.