Battery housing case

Abstract

To provide a battery storage case capable of efficiently receiving an input impact load by a part other than a battery cell while avoiding increase in size and weight of the whole.SOLUTION: The battery housing case includes a pair of main frame members, a cross member, and a bottom wall member. The pair of main frame members extend in a first direction intersecting the vertical direction, and are spaced apart from each other in a second direction intersecting the first direction and the vertical direction. The cross member extends in the second direction, and both ends of the cross member are connected to the main frame members. The bottom wall member is connected to each main frame member and covers a lower space between the pair of main frame members. The main frame member includes an upper wall portion disposed at a position higher than the bottom wall member. The upper wall portion includes an inclined region and a vehicle body coupling region. The inclined region is inclined downward from the inner side in the second direction toward the outer side in the second direction. The vehicle body connecting region extends substantially horizontally outward in the second direction from a lower end of the inclined region and is connected to a frame member of the vehicle body.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a battery housing case that houses battery cells inside and is attached to a frame member of a vehicle. [Background Art]

[0002] As a vehicle lower body structure, there is known a structure in which a battery housing case that houses battery cells inside is installed across left and right side sills of a vehicle body (see, for example, Patent Document 1).

[0003] In the battery housing case disclosed in Patent Document 1, fixing pieces extending outward in the vehicle width direction are provided extending from left and right side edge portions on the lower end side of the case body, and the fixing pieces are fixed to lower surfaces of the corresponding left and right side sills (rockers) by fastening members. The fixing pieces extending from the case body are formed of a plate-shaped member, and a root portion thereof (a portion adjacent to the case body) is inclined upward toward the outside in the vehicle width direction.

[0004] In the vehicle lower body structure disclosed in Patent Document 1, energy absorbing structures are provided on the left and right side sills that support the battery housing case. Therefore, when a large impact load is applied to a side surface of the side sill from the outside, the energy of the impact load can be absorbed by the side sills. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent No. 7306544 [Summary of the Invention] [Problem to be Solved by the Invention]

[0006] However, in the conventional battery housing case described above, the base of the fixing piece that fastens to the side sill is inclined upward from the side edge of the lower end of the case body toward the outside in the vehicle width direction. Therefore, when the side sill is subjected to an impact load from the side and displaced significantly inward in the vehicle width direction, there is a concern that the base of the fixing piece will bend upward, and a large load will be applied from the side sill to the upper area of ​​the side wall (side frame) of the case body. In this case, from the viewpoint of protecting the battery cells inside the battery housing case, it becomes necessary to provide a large cross member or a number of cross members on the case body. This causes the case body to become larger and heavier, so improvement is desired.

[0007] Therefore, the present invention aims to provide a battery housing case that can efficiently absorb incoming impact loads in parts other than the battery cells, while avoiding an overall increase in size and weight. Furthermore, the present invention contributes to energy efficiency by making the entire battery housing case smaller and lighter. [Means for solving the problem]

[0008] To solve the above problems, the battery housing case according to the present invention employs the following configuration. A battery housing case according to one aspect of the present invention is attached to a skeletal member at the bottom of the vehicle body (for example, a side sill 3 in the embodiment) and houses battery cells (for example, battery cells 6 in the embodiment) inside, comprising: a pair of main skeletal members (for example, a main skeletal member 11 in the embodiment) extending along a first direction intersecting the vertical direction and spaced apart from each other in a second direction intersecting the first direction and the vertical direction; cross members (for example, a first cross member 12f, a second cross member 12s, and a third cross member 12t in the embodiment) extending along the second direction and having both ends in the extending direction connected to each of the main skeletal members; and a pair of the main skeletal members connected to each of the main skeletal members. The main frame member comprises a bottom wall member (for example, bottom wall member 13 in the embodiment) that covers the lower space between the main frame members and on which the battery cells are mounted on its upper surface, and the main frame member has an upper wall portion (for example, upper wall portion 17 in the embodiment) positioned at a higher height than the bottom wall member, and the upper wall portion comprises an inclined region (for example, inclined region 17b in the embodiment) that slopes downward from the second direction inward, which is the side closer to the cross member in the second direction, to the second direction outward, which is the side further away from the cross member, and a vehicle body connecting region (for example, vehicle body connecting region 17c in the embodiment) that extends substantially horizontally from the lower end of the inclined region outward in the second direction and is connected to the frame member.

[0009] In the battery housing case of this embodiment, when an impact load directed inward in the second direction is applied to the vehicle body connection region of the main frame member through the vehicle body frame member, the load concentrates near the boundary between the vehicle body connection region and the inclined region of the upper wall portion of the main frame member. At this time, since the inclined region of the upper wall portion is inclined downward toward the outward direction in the second direction, the area near the boundary between the vehicle body connection region and the inclined region of the upper wall portion displaces downward and bends in a concave shape. As a result, the main frame member transmits the impact load inward in the second direction without the outer portion in the second direction being lifted significantly upward. Consequently, the impact load is effectively transmitted to the lower bottom wall member of the cross member through the main frame member. Therefore, in the battery housing case of this embodiment, the impact load input from the skeletal members under the vehicle body can be efficiently absorbed not only by the cross members but also by the bottom wall members. Thus, by adopting the battery housing case of this embodiment, it becomes possible to efficiently absorb the input impact load with parts other than the battery cells while suppressing the need to enlarge the cross members or increase the number of cross members installed.

[0010] It is desirable that a curved ridge line (for example, the curved ridge line 20 in the embodiment) extending along the first direction is arranged between the inclined region of the upper wall and the vehicle body connecting region.

[0011] In this case, since a bending ridge is positioned between the inclined region of the upper wall and the vehicle body connection region, when an impact load is applied from the second direction outside the main frame member, the upper wall is more likely to bend downward in a concave shape starting from the bending ridge. Therefore, when this configuration is adopted, it becomes easier to obtain a desirable deformation behavior of the upper wall that allows for good transmission of the load from the main frame member to the bottom wall member.

[0012] The main skeletal member further has a lower wall portion (for example, a lower wall portion 18 in the embodiment) positioned below the upper wall portion and forming a closed cross section along the first direction together with the upper wall portion, and the inner end of the lower wall portion in the second direction may be positioned at a height close to the bottom wall member.

[0013] In this case, since the upper and lower walls of the main frame member form a closed cross-section along the first direction, even if the area near the boundary between the vehicle body connection region and the inclined region of the upper wall bends downward in a concave shape, the impact load can be efficiently transmitted to the bottom wall member through the lower wall.

[0014] Within the closed cross-section of the main skeletal member, a first reinforcing rib (for example, the first reinforcing rib 21 in the embodiment) may be provided, which is inclined inward in the second direction from a position inward in the second direction from a position inward in the inclined region of the upper wall portion downward, and which connects the upper wall portion and the lower wall portion.

[0015] In this configuration, a first reinforcing rib is provided that slopes downward inward in the second direction from a position two directions inward of the inclined region of the upper wall, and this first reinforcing rib connects the upper wall and the lower wall. Therefore, when an impact load directed inward in the second direction is applied to the vehicle body connection region of the main frame member, a reaction force acts from the first reinforcing rib at a position two directions inward of the inclined region of the upper wall to restrict the downward tilting of the second-inward end of the inclined region. As a result, the upper wall is prone to bending downward in a concave shape near the boundary between the vehicle body connection region and the inclined region. Furthermore, in this configuration, since the first reinforcing rib is inclined downwards in the second direction inward, it becomes possible to effectively transmit a portion of the impact load transmitted to the inward end of the inclined region of the upper wall to the lower wall through the first reinforcing rib. Therefore, when this configuration is adopted, the input impact load can be effectively transmitted through the main frame member to the bottom wall member on the lower side of the cross member.

[0016] Within the closed cross-section of the main skeletal member, a second reinforcing rib (for example, the second reinforcing rib 22 in the embodiment) may be provided, which is inclined downward and inward in the second direction from a position outside the inclined region of the upper wall portion, and connects the upper wall portion and the lower wall portion.

[0017] In this configuration, the second reinforcing rib, which is connected to a position outside the inclined region of the upper wall in the second direction, is inclined downwards and inwards in the second direction. This makes it possible to effectively transmit a portion of the impact load applied to the vehicle body connection region to the lower wall through the second reinforcing rib. Therefore, when this configuration is adopted, the load can be efficiently transmitted to the bottom wall member through the second reinforcing rib and the lower wall even before the area near the boundary between the vehicle body connection area and the inclined area undergoes a large downward concave bending deformation.

[0018] The upper wall portion may further include a base-side horizontal region (for example, the base-side horizontal region 17a in the embodiment) that extends substantially horizontally toward the second direction toward the inclined region.

[0019] In this case, since the base-side horizontal region is arranged inward of the inclined region in the second direction, it is possible to suppress early deformation of the portion inward of the inclined region of the upper wall in the second direction at the initial input stage of an impact load. Therefore, when this configuration is adopted, bending deformation can be reliably caused first in the vicinity of the boundary between the vehicle body connecting region and the inclined region at the initial input stage of an impact load.

[0020] The bottom wall member may have a multi-wall structure with a hollow portion.

[0021] In this case, since the bottom wall member has a highly rigid multi-wall structure, the impact load input through the main frame member can be reliably received by the bottom wall member.

[0022] The main frame member is further connected at its inner side in the second direction to the cross member and the bottom wall member, and further includes a hollow base frame portion (for example, the base frame portion 15 in the embodiment) that stands upward from the height position connected to the bottom wall member, the upper wall and the lower wall are connected to the outer side of the base frame portion in the second direction, and it is preferable that the upper wall is connected to a center position in the height direction of the base frame portion, or a position slightly lower than the center position.

[0023] In this case, since the upper wall is connected to the center position in the height direction of the base frame portion, or a position slightly lower than the center position, the impact load transmitted from the upper wall to the base frame portion can be favorably transmitted to the bottom wall member. Further, in the late stage of impact load input, the base frame portion can be favorably deformed by the load input from the upper wall to the base frame portion. Therefore, the energy of the impact load can be absorbed through deformation of the base frame portion. Effects of the Invention

[0024] According to the battery housing case according to the present invention, an applied impact load can be efficiently received by portions other than battery cells while avoiding an increase in overall size and weight. Therefore, when the battery housing case according to the present invention is employed, the reduction in size and weight of the entire battery housing case can contribute to improving the energy efficiency of a vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] [Figure 1] A cross-sectional view illustrating a structure of a lower vehicle body portion of the vehicle according to the embodiment. [Figure 2] A perspective view of the battery housing case according to the embodiment. [Figure 3] An exploded perspective view of the battery housing case according to the embodiment. [Figure 4] A partial cross-sectional view of the battery housing case according to the embodiment. [Figure 5] A cross-sectional view for explaining load transmission of the battery housing case according to the embodiment. [Figure 6] A cross-sectional view for explaining load transmission of a modified battery housing case. [Figure 7] A cross-sectional view for explaining load transmission of another modified battery housing case. [Figure 8] A cross-sectional view for explaining load transmission of still another modified battery housing case. MODE FOR CARRYING OUT THE INVENTION

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that, in appropriate positions in the drawings, an arrow FR pointing toward the front of the vehicle, an arrow UP pointing toward the upper side of the vehicle, and an arrow LH pointing toward the left side of the vehicle are shown. In addition, in the embodiments and modified examples thereof described below, common portions are assigned the same reference numerals, and overlapping descriptions are omitted.

[0027] FIG. 1 is a diagram showing a lower vehicle body structure of a vehicle 1. FIG. 1 is a cross-sectional view obtained by cutting the lower portion of the vehicle 1 along a direction orthogonal to the longitudinal direction of the vehicle body. A pair of side sills 3, which are structural members of the vehicle body, are positioned at the lower ends of both sides in the vehicle width direction of the passenger compartment 2, extending substantially along the longitudinal direction of the vehicle body. In Figure 1, only one side sill 3 is shown. Floor panels 4 are installed on the left and right side sills 3. Below the floor panels 4, a battery housing case 10 is positioned substantially along the lower surface of the floor panels 4. The battery housing case 10 comprises a case body 25 on which a plurality of battery cells 6 and control equipment (not shown) are mounted on the upper side, and a cover member 30 that covers the upper part of the case body 25. The case body 25 is formed in a substantially rectangular shape when viewed from above. The left and right side edges of the case body 25 are fixed to the lower surfaces of the left and right side sills 3 by fastening members 31 (see Figures 4 and 5).

[0028] The side sill 3 is constructed by sandwiching a stiffener 3C between a hat-shaped side sill inner 3A and a side sill outer 3B. The side sill inner 3A and the side sill outer 3B have joining flanges 3Af and 3Bf above and below each other. The upper and lower joining flanges 3Af and 3Bf of the side sill inner 3A and the side sill outer 3B are positioned opposite each other. The opposing joining flanges 3Af and 3Bf are connected by welding or the like with the stiffener 3C sandwiched between them. The side sill inner 3A has an inner bulge 3Ac with a U-shaped cross-section that bulges inward in the vehicle width direction from the base of the upper and lower joining flanges 3Af and 3Bf. The left and right side edges of the case body 25 are fixed to the lower surface of the inner bulge 3Ac of the side sill inner 3A.

[0029] Figure 2 is a perspective view of the battery housing case 10, and Figure 3 is an exploded perspective view of the battery housing case 10. Note that the cover member 30 is omitted in Figures 2 and 3. The battery housing case 10 has a case body 25 which includes a pair of main frame members 11 that extend substantially along the longitudinal direction of the vehicle body. The pair of main frame members 11 are spaced apart in the vehicle width direction. The pair of main frame members 11 are connected by a first cross member 12f, a second cross member 12s, and a third cross member 12t, which extend along the vehicle width direction. The first cross member 12f has both ends in the extending direction connected to the front ends of the left and right main frame members 11, and the second cross member 12s has both ends in the extending direction connected to the rear ends of the left and right main frame members 11. The third cross member 12t has both ends in the extending direction connected to approximately the center position in the longitudinal direction of the left and right main frame members 11.

[0030] The first cross member 12f and the second cross member 12s are welded to the left and right main frame members 11. The central third cross member 12t consists of a lower portion 12tl which is welded to the left and right main frame members 11, and an upper portion 12tu which is bolted to the upper surface of the lower portion 12tl.

[0031] The case body 25 further includes a bottom wall member 13 that covers the space below between a pair of main frame members 11. The bottom wall member 13 is formed in a rectangular shape in plan view, and the lower ends of the first, second, and third cross members 12f, 12s, and 12t are connected to the pair of main frame members 11 on its upper surface. Multiple (four) battery units 7 (multiple battery cells 6) are placed on the upper surface of the bottom wall member 13. Two battery units 7 are placed side by side in the vehicle width direction on the front upper surface of the bottom wall member 13 with the third cross member 12t in between, and the remaining two battery units 7 are placed similarly side by side in the vehicle width direction on the rear upper surface of the bottom wall member 13 with the third cross member 12t in between. The battery units 7 (multiple battery cells 6) housed in the case body 25 are surrounded on their outer perimeter by the pair of main frame members 11 and the first, second, and third cross members 12f, 12s, and 12t. Furthermore, each battery unit 7 housed in the case body 25 is positioned at a distance from the adjacent main frame member 11 so as not to be in contact with it. In other words, a space is provided between the left and right main frame members 11 and the adjacent battery unit 7.

[0032] The bottom wall member 13 comprises a base wall 7b facing the battery unit 7 housing and a flow path forming wall 7f joined to its lower surface. The flow path forming wall 7f forms a coolant flow path 14 between itself and the lower surface of the base wall 7b for circulating coolant inside. Multiple battery cells 6 housed in the battery housing case 10 are cooled by circulating coolant through the coolant flow path 14. In this embodiment, the bottom wall member 13 has a multi-wall structure with a hollow section inside, formed by a base wall 7b and a flow path forming wall 7f below it.

[0033] Each battery unit 7 has multiple battery cells 6 stacked within a rectangular unit cover that is narrow in the vertical direction. The battery cells 6 are grouped into battery units 7 in predetermined numbers and housed in a battery housing case 10. Furthermore, the number of battery units 7 housed in the battery housing case 10 is not limited to four; any number can be selected depending on the size of the battery housing case 10 and the layout of the mounted components.

[0034] Furthermore, an equipment mounting frame 8 is installed on the upper part of the first cross member 12f and the second cross member 12s of the battery housing case 10. The equipment mounting frame 8 is installed in the center of the first cross member 12f and the second cross member 12s in the vehicle width direction, straddling the front and rear of the central area in the vehicle width direction above the four battery units 7. Control equipment and its wiring, etc. (not shown), are mounted on the upper part of the equipment mounting frame 8.

[0035] In this embodiment, the vehicle body's longitudinal direction is the first direction intersecting the vertical direction, and the vehicle width direction is the second direction intersecting the first direction and the vertical direction. The pair of main frame members 11 extend along the first direction (vehicle body's longitudinal direction) and are spaced apart from each other in the second direction (vehicle width direction). The first, second, and third cross members 12f, 12s, and 12t extend along the second direction (vehicle width direction), and both ends in the direction of extension are connected to each main frame member 11. Furthermore, in this embodiment, the inner side in the vehicle width direction is the inner side in the second direction, and the outer side in the vehicle width direction is the outer side in the second direction.

[0036] Figure 4 is a cross-sectional view of a portion of the battery housing case 10. Figure 4 is a cross-sectional view of the battery housing case 10 cut in a direction perpendicular to the longitudinal direction of the vehicle body. The main frame member 11 has a hollow base frame portion 15 to which the extended ends of the first, second, and third cross members 12f, 12s, and 12t are connected on the inner surface in the vehicle width direction, and a hollow mounting frame portion 16 that extends outward in the vehicle width direction from the outer end of the base frame portion 15 in the vehicle width direction. The base frame section 15 has a vertically elongated rectangular cross-section perpendicular to the longitudinal direction of the vehicle body. The rectangular cross-section of the base frame section 15 extends substantially along the longitudinal direction of the vehicle body.

[0037] The mounting frame portion 16 has an upper wall portion 17 whose inner end in the vehicle width direction is connected to the central position c1 in the height direction of the base frame portion 15, and a lower wall portion 18 whose inner end in the vehicle width direction is connected to the lower end of the base frame portion 15. The lower wall portion 18 is positioned at a height close to the bottom wall member 13 (approximately the same height as the bottom wall member 13). The outer ends of the upper wall portion 17 and the lower wall portion 18 in the vehicle width direction are closed by end walls 19 that stand substantially along the vertical direction. The mounting frame portion 16 forms a horizontally elongated, roughly rectangular closed cross section by the side wall on the outer side in the vehicle width direction of the base frame portion 15, the upper wall portion 17, the lower wall portion 18, and the end wall 19. This closed cross section extends in the longitudinal direction of the vehicle body. In this embodiment, the upper wall portion 17 is connected to the central position c1 in the height direction of the base frame portion 15. However, the connection position of the upper wall portion 17 to the base frame portion 15 may be a position slightly lower than the central position c1 in the height direction of the base frame portion 15.

[0038] The upper wall portion 17 of the mounting frame portion 16 is positioned at a higher height than the bottom wall member 13. The upper wall portion 17 includes a base-side horizontal region 17a that extends substantially horizontally outward in the vehicle width direction from the side wall of the base frame portion 15, an inclined region 17b that slopes downward outward in the vehicle width direction from the outer end of the base-side horizontal region 17a, and a vehicle body connecting region 17c that extends substantially horizontally outward in the vehicle width direction from the lower end of the inclined region 17b and connects to the lower surface of the inner bulge portion 3Ac of the side sill 3. A curved ridge line 20 extending along the longitudinal direction of the vehicle body is positioned between the inclined region 17b and the vehicle body connecting region 17c.

[0039] The lower wall portion 18 includes a base-side region 18a extending outward in the vehicle width direction from the lower end of the side wall of the base frame portion 15, a gently sloping region 18b extending outward in the vehicle width direction while gently sloping upward from the outer end of the base-side region 18a in the vehicle width direction, and an outer extension region 18c extending substantially horizontally outward in the vehicle width direction from the upper end of the gently sloping region 18b. The end of the outer extension region 18c of the lower wall portion 18 and the end of the vehicle body connecting region 17c of the upper wall portion 17 are connected by an end wall 19.

[0040] Within the closed cross-section of the mounting frame portion 16 (main frame member 11), a first reinforcing rib 21 is provided, which slopes inward in the vehicle width direction from a position inward in the vehicle width direction from a position inward in the vehicle width direction than the inclined region 17b of the upper wall portion 17 (a position close to the inclined region 17b in the base-side horizontal region 17a). The upper end of the first reinforcing rib 21 is connected to the upper wall portion 17, and the lower end is connected to the boundary between the base-side region 18a and the gently sloping region 18b of the lower wall portion 18.

[0041] Furthermore, within the closed cross-section of the mounting frame portion 16 (main frame member 11), a second reinforcing rib 22 is provided, which slopes inward in the vehicle width direction from a position outside the vehicle width direction (close to the inclined region 17b of the vehicle body connecting region 17c) below the inclined region 17b of the upper wall portion 17. The upper end of the second reinforcing rib 22 is connected to the upper wall portion 17, and the lower end is connected to the boundary between the outward extension region 18c and the gently sloping region 18b of the lower wall portion 18.

[0042] Next, we will explain the deformation behavior of the battery housing case 10, which contains the battery cells 6 (battery unit 7), when an impact load is applied from the side of the vehicle body while the battery housing case 10 is attached to the vehicle 1, and how the load is transmitted at that time.

[0043] Figure 5 is a cross-sectional view illustrating load transfer in the battery housing case 10. As shown in Figures 4 and 5, when an impact load F is applied from the side of the vehicle 1, the impact load F is transmitted to the vehicle body connection region 17c of the main frame member 11 of the battery housing case 10 through one of the left or right side sills 3. When a load directed inward in the vehicle width direction is applied to the vehicle body connection region 17c of the main frame member 11, the load concentrates near the boundary between the vehicle body connection region 17c and the inclined region 17b of the upper wall portion 17 (bent ridge line 20). At this time, since the inclined region 17b of the upper wall portion 17 is inclined downward toward the outward side in the vehicle width direction, as shown by the dashed line in Figure 4, the area near the boundary between the vehicle body connection region 17c and the inclined region 17b of the upper wall portion 17 is displaced downward and bends in a concave shape. As a result, the main frame member 11 transmits the impact load F inward in the vehicle width direction without the outer portion in the vehicle width direction lifting significantly upward. Therefore, a large portion of the impact load is transmitted from the main frame member 11 to the highly rigid bottom wall member 13.

[0044] In the initial stages of impact load F input, as described above, the area near the boundary between the vehicle body connection region 17c and the inclined region 17b of the upper wall portion 17 bends downward, while the outer portion of the mounting frame portion 16 in the vehicle width direction rotates inward in the vehicle width direction with the bend as a pivot point, and deforms by collapsing together with the side sill 3. At this time, the upper wall portion 17 of the mounting frame portion 16 is supported by the first reinforcing rib 21 in the portion inward in the vehicle width direction from the inclined region 17b, and the first reinforcing rib 21 is inclined downward inward in the vehicle width direction. Therefore, the downward tilting of the portion of the upper wall portion 17 inward in the vehicle width direction from the inclined region 17b is restricted by the first reinforcing rib 21. Consequently, the bending deformation of the upper wall portion 17 near the boundary between the vehicle body connection region 17c and the inclined region 17b proceeds more reliably.

[0045] Furthermore, a large portion of the impact load F applied to the vehicle body connection area 17c on the upper wall portion 17 side of the mounting frame portion 16 is transmitted to the lower wall portion 18 through the second reinforcing rib 22 and the first reinforcing rib 21. The numbers indicated within the arrows in Figure 5 represent the ratio of the load transmitted to each part of the upper wall portion 17 and the lower wall portion 18, and the ratio of the load transmitted to the cross member (for example, the third cross member 12t) and the bottom wall member 13, when the impact load applied to the vehicle body connection area 17c is set to "10".

[0046] As described above, the battery housing case 10 of this embodiment has an upper wall portion 17 positioned at a height higher than the bottom wall member 13 on the main frame member 11, and the upper wall portion 17 comprises an inclined region 17b and a vehicle body connecting region 17c. The inclined region 17b slopes downward from the inside to the outside in the vehicle width direction, and the vehicle body connecting region 17c extends substantially horizontally outward in the vehicle width direction from the lower end of the inclined region 17b and is connected to the side sill 3, which is a frame member of the vehicle. Therefore, when an impact load directed inward in the vehicle width direction is applied to the vehicle body connecting region 17c of the main frame member 11 through the side sill 3 on the side of the vehicle, the area near the boundary between the vehicle body connecting region 17c and the inclined region 17b of the upper wall portion 17 is displaced downward and bends into a concave shape. As a result, when an impact load is applied, the outer portion of the main frame member 11 in the vehicle width direction does not lift significantly upward, and the input load can be effectively transmitted through the main frame member 11 to the lower bottom wall members 13 of the cross members 12f, 12s, and 12t. Therefore, in the battery housing case 10 of this embodiment, the impact load input from the side sill 3 can be efficiently absorbed not only by the cross members 12f, 12s, and 12t, but also by the bottom wall member 13, which has high horizontal rigidity. Thus, when the battery housing case 10 of this embodiment is adopted, the impact load input can be efficiently absorbed by parts other than the battery cells 6 while suppressing the need to enlarge the cross members or increase the number of cross members installed.

[0047] Furthermore, in this embodiment, the battery housing case 10 is provided with a bent ridge line 20 extending along the longitudinal direction of the vehicle body between the inclined region 17b of the upper wall portion 17 of the main frame member 11 and the vehicle body connecting region 17c. Therefore, when an impact load is applied from the outside in the vehicle width direction of the main frame member 11, the upper wall portion 17 is more likely to bend downward in a concave shape starting from the bent ridge line 20. Consequently, when this configuration is adopted, it is easier to obtain a desirable deformation behavior of the upper wall portion 17 that allows for good transmission of load from the main frame member 11 to the bottom wall member 13.

[0048] Furthermore, in this embodiment, the battery housing case 10 has a main frame member 11 which has an upper wall portion 17 and a lower wall portion 18, and the upper wall portion 17 and the lower wall portion 18 form a closed cross section that is aligned with the longitudinal direction of the vehicle body. The inner end of the lower wall portion 18 in the vehicle width direction is positioned at a height close to the bottom wall member 13 (approximately the same height as the bottom wall member 13). Therefore, even if the area near the boundary between the vehicle body connection region 17c and the inclined region 17b of the upper wall portion 17 bends downward in a concave shape when an impact load is applied, the impact load can be efficiently transmitted to the bottom wall member 13 through the lower wall portion 18.

[0049] Furthermore, in this embodiment, the battery housing case 10 is provided with a first reinforcing rib 21 within the closed cross-section of the main frame member 11, which inclins inward in the vehicle width direction from a position inward in the vehicle width direction from a position inward in the vehicle width direction from the inclined region 17b of the upper wall portion 17, and the first reinforcing rib 21 is connected to the upper wall portion 17 and the lower wall portion 18. Therefore, when an impact load directed inward in the vehicle width direction is applied to the vehicle body connection region 17c of the main frame member 11, a reaction force acts from the first reinforcing rib 21 to restrict the downward tilting of the inward end of the inclined region 17b in the vehicle width direction. At this time, since the first reinforcing rib 21 is inclined inward in the vehicle width direction from a position inward in the vehicle width direction from a position inward in the vehicle width direction from the inclined region 17b, the upper side does not tilt inward in the vehicle width direction when subjected to a load, and the downward tilting of the inward end of the inclined region 17b in the vehicle width direction can be restricted. As a result, the upper wall portion 17 is more likely to bend downward in a concave shape near the boundary between the vehicle body connection region 17c and the inclined region 17b. Furthermore, in this configuration, since the first reinforcing rib 21 is inclined downward and inward in the vehicle width direction, a portion of the impact load transmitted to the inward end in the vehicle width direction of the inclined region 17b of the upper wall portion 17 can be effectively transmitted to the lower wall portion 18 side through the first reinforcing rib 21. Therefore, when the battery housing case 10 of this embodiment is adopted, the input impact load can be effectively transmitted through the main frame member 11 to the lower bottom wall member 13 of the cross members 12f, 12s, and 12t.

[0050] Furthermore, in this embodiment, the battery housing case 10 is provided with a second reinforcing rib 22 within the closed cross-section of the main frame member 11, which slopes inward in the vehicle width direction from a position outside the vehicle width direction relative to the inclined region 17b of the upper wall portion 17, and the second reinforcing rib 22 is connected to the upper wall portion 17 and the lower wall portion 18. As a result, a portion of the impact load input to the vehicle body connection region 17c can be effectively transmitted to the lower wall portion 18 through the second reinforcing rib 22. Therefore, even before the area near the boundary between the vehicle body connection region 17c and the inclined region 17b undergoes a large downward concave bending deformation, the load can be efficiently transmitted to the bottom wall member 13 through the second reinforcing rib 22 and the lower wall portion 18.

[0051] Figure 6 is a cross-sectional view similar to Figure 5, showing a modified example in which the first reinforcing rib 21A and the second reinforcing rib 22A are not inclined inward in the vehicle width direction from the upper end to the lower end, but are instead erected vertically. In this modified example, since the first reinforcing rib 21A and the second reinforcing rib 22A are not inclined inward in the vehicle width direction from the upper end to the lower end, the load cannot be transmitted to the bottom wall member 13 as efficiently as in the embodiments shown in Figures 4 and 5, as is clear from the load sharing ratio figures indicated within the arrows in Figure 6. In the embodiments shown in Figures 4 and 5, the first reinforcing rib 21A and the second reinforcing rib 22A are inclined inward in the vehicle width direction from the upper end to the lower end, so the input impact load can be transmitted to the bottom wall member 13 efficiently.

[0052] Furthermore, in this embodiment, the battery housing case 10 is provided with a base-side horizontal region 17a that extends substantially horizontally inward in the vehicle width direction, on the inclined region 17b of the upper wall 17. Therefore, it is possible to suppress the deformation of the portion of the upper wall 17 that is inward in the vehicle width direction from the inclined region 17b at the initial stage of impact load application. Consequently, when this configuration is adopted, the area near the boundary between the vehicle body connection region 17c and the inclined region 17b can be reliably bent first at the initial stage of impact load application.

[0053] Furthermore, the battery housing case 10 of this embodiment has a multi-wall structure in which the bottom wall member 13 has a hollow section. Therefore, when the battery housing case 10 of this embodiment is adopted, the impact load input through the main frame member 11 can be reliably absorbed by the bottom wall member 13, which has a multi-wall structure with high horizontal rigidity.

[0054] Furthermore, the battery housing case 10 of this embodiment includes a hollow base frame portion 15 that rises upward from a height position where the main frame member 11 is connected to the bottom wall member 13. The base frame portion 15 is connected to the cross members 12f, 12s, 12t and the bottom wall member 13 on its inner side in the vehicle width direction. The upper wall portion 17 and lower wall portion 18 of the main frame member 11 are connected to the outer side of the base frame portion 15 in the vehicle width direction, and the upper wall portion 17 is connected to the central position c1 in the height direction of the base frame portion 15, or slightly below the central position c1. Therefore, when this configuration is adopted, the impact load transmitted from the upper wall portion 17 to the base frame portion 15 can be effectively transmitted by the bottom wall member 13. In addition, in the later stages of impact load input, the base frame portion 15 can be effectively deformed by the load input from the upper wall portion 17 to the base frame portion 15. In other words, a load is applied from the upper wall portion 17 to approximately the center of the hollow base frame portion 15 in the height direction, thereby allowing the base frame portion 15 to be deformed effectively. Therefore, when this configuration is adopted, the deformation of the base frame 15 allows for efficient absorption of the energy of the impact load.

[0055] Figure 7 is a cross-sectional view similar to Figure 5, showing a modified example in which the upper wall portion 17 of the main frame member 11 is connected to a position above the central position c1 in the height direction of the base frame portion 15. Figure 8 is a cross-sectional view similar to Figure 5, showing another modified example in which the upper wall portion 17 of the main frame member 11 is connected to the upper end of the base frame portion 15. In these modified examples, a base-side inclined region 17aA is arranged on the inside of the inclined region 17b in the vehicle width direction, and the end of the base-side inclined region 17aA is connected to the base frame portion 15. In the modified examples shown in Figures 7 and 8, the upper wall portion 17 is connected to a position above the central position c1 in the height direction of the base frame portion 15. As is clear from the load sharing ratio figures indicated within the arrows in Figures 7 and 8, the load cannot be transmitted to the bottom wall member 13 as efficiently as in the embodiments shown in Figures 4 and 5. In the embodiments shown in Figures 4 and 5, the upper wall portion 17 is connected to the central position c1 in the height direction of the base frame portion 15, or slightly below the central position c1. Therefore, the input impact load can be transmitted to the bottom wall member 13 efficiently.

[0056] It should be noted that the present invention is not limited to the embodiments described above, and various design modifications are possible without departing from the spirit of the invention. For example, in the above embodiment, three cross members are provided spaced apart in the front-rear direction and connected to a pair of main frame members 11, but the number of cross members is not limited to three. The number of cross members may be four or more, or two or fewer.

[0057] Furthermore, in the above embodiment, a pair of main frame members 11 extend along the longitudinal direction of the vehicle body and are spaced apart from each other in the vehicle width direction, and the first, second, and third cross members 12f, 12s, and 12t are arranged along the vehicle width direction. However, the arrangement of the main frame members and cross members is not limited to this. For example, a pair of main frame members may be arranged to extend along the vehicle width direction and be spaced apart from each other in the longitudinal direction of the vehicle body, and the cross members may be arranged along the longitudinal direction of the vehicle body.

[0058] Furthermore, in the above embodiment, the bottom wall member 13 is composed of a multi-wall structure consisting of a base wall 7b and a flow path forming wall 7f, but the multi-wall structure is not limited to this. The bottom wall member 13 may also have a multi-wall structure formed by a dedicated member separate from the coolant flow path 14. Note that it is not essential for the bottom wall member 13 to have a multi-wall structure; the bottom wall member 13 only needs to have a structure with high horizontal rigidity. [Explanation of Symbols]

[0059] 3…Side sill (framework component) 6…Battery cell 10…Battery housing case 11…Main skeleton members 12f...First cross member (cross member) 12s…Second cross member (cross member) 12m…3rd cross member (cross member) 13…Bottom wall member 15…Base frame section 17...Top wall part 17a…Base side horizontal area 17b…Slope area 17c... Vehicle body coupling area 18…Lower wall part 20... Bent ridge 21,21A…First reinforcing rib 22,22A…Second reinforcing rib

Claims

1. A battery housing case attached to a skeletal member at the bottom of the vehicle body, with battery cells housed inside, A pair of main skeletal members extending along a first direction intersecting the vertical direction and arranged spaced apart from each other in a second direction intersecting the first direction and the vertical direction, A cross member extending along the second direction and having both ends in the extension direction connected to each of the main frame members, Each of the main frame members is connected to a bottom wall member that covers the space below between a pair of main frame members, and on the upper side of which the battery cell is mounted. The main frame member has an upper wall portion positioned at a higher height than the bottom wall member, The upper wall portion includes an inclined region that slopes downward from the inner side in the second direction, which is the side adjacent to the cross member in the second direction, to the outer side in the second direction, which is the side separated from the cross member, and a vehicle body connecting region that extends substantially horizontally outward in the second direction from the lower end of the inclined region and is connected to the frame member. The main skeletal member further has a lower wall portion positioned below the upper wall portion and forming a closed cross section along the first direction together with the upper wall portion, The inner end of the lower wall portion in the second direction is positioned at a height close to the bottom wall member. The battery housing case is characterized in that the lower wall portion comprises a base-side region extending from the inside in the second direction toward the outside in the second direction, a gently sloping region extending toward the outside in the second direction while gently sloping upward from the outer end of the base-side region toward the outside in the second direction, and an outward-extending region extending substantially horizontally toward the outside in the second direction from the upper end of the gently sloping region.

2. The battery housing case according to claim 1, wherein a curved ridge extending in the first direction is arranged between the inclined region of the upper wall and the vehicle body connecting region.

3. The battery housing case according to claim 1, characterized in that a first reinforcing rib is provided within the closed cross-section of the main frame member, inclined inward in the second direction from a position inward in the second direction from a position inward in the second direction from a position inward in the upper wall portion than the inclined region, and connecting the upper wall portion and the lower wall portion.

4. The battery housing case according to claim 3, characterized in that a second reinforcing rib is provided within the closed cross-section of the main skeletal member, inclined inward in the second direction from a position outside the inclined region of the upper wall portion in the second direction downward, and connecting the upper wall portion and the lower wall portion.

5. The battery housing case according to claim 4, characterized in that the upper wall portion further comprises a base-side horizontal region extending substantially horizontally toward the inward direction in the second direction to the inclined region.

6. The battery housing case according to claim 1, characterized in that the bottom wall member has a multi-wall structure with a hollow portion.

7. The main skeletal member has its inner side in the second direction connected to the cross member and the bottom wall member, and further has a hollow base frame portion that rises upward from the height position where it is connected to the bottom wall member. The upper wall portion and the lower wall portion are connected to the second outward side of the base frame portion. The battery housing case according to claim 1, characterized in that the upper wall portion is connected to the base frame portion at the central position in the height direction, or at a position slightly below the central position.

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