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 therein and is attached to a frame member of a vehicle. [Background technology]

[0002] BACKGROUND ART Known vehicle underbody structures include battery housing cases that house battery cells and are mounted on the left and right side sills of a vehicle body (see, for example, Patent Document 1).

[0003] The battery housing case disclosed in Patent Document 1 has fixing pieces extending outward in the vehicle width direction from the left and right side edges of the lower end of the case body, and the fixing pieces are fixed to the undersides of the corresponding left and right side sills (rockers) with fastening members. The fixing pieces extending from the case body are made of plate-shaped members, and their bases (portions close to the case body) are inclined upward toward the outside in the vehicle width direction.

[0004] In the vehicle underbody structure disclosed in Patent Document 1, energy absorption structures are provided on the left and right side sills that support the battery housing case. Therefore, when a large external impact load acts on the side surface of the side sill, the energy of the impact load can be absorbed by the side sill. [Prior art documents] [Patent documents]

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

[0006] However, in the above-mentioned conventional battery housing case, the base of the fixing piece fastened 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 receives a lateral impact load and is significantly displaced toward the inside in the vehicle width direction, the base of the fixing piece may bend upward, raising concerns that a large load may be input from the side sill to the upper region of the side wall (side frame) of the case body. In this case, in order to protect the battery cells inside the battery housing case, it becomes necessary to provide a large cross member or multiple cross members to the case body. This increases the size and weight of the case body, and therefore improvement is desired.

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

[0008] In order 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 a battery housing case attached to a frame member (e.g., a side sill 3 in the embodiment) below a vehicle body, and housing a battery cell (e.g., a battery cell 6 in the embodiment), and includes a pair of main frame members (e.g., a main frame member 11 in the embodiment) extending along a first direction intersecting with a vertical direction and spaced apart from each other in a second direction intersecting with the first direction and the vertical direction, cross members (e.g., 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 extension direction connected to each of the main frame members, and a pair of cross members (e.g., a first cross member 12f, a second cross member 12s, and a third cross member 12t) connected to each of the main frame members. The battery cell is mounted on an upper surface of a bottom wall member (e.g., bottom wall member 13 in the embodiment) that covers the lower space between the main skeletal members, and the main skeletal member has an upper wall portion (e.g., upper wall portion 17 in the embodiment) that is positioned at a higher height than the bottom wall member, and the upper wall portion has an inclined region (e.g., inclined region 17b in the embodiment) that slopes downward from the inner side of the second direction, which is the side that is close to the cross member in the second direction, to the outer side of the second direction, which is the side that is away from the cross member, and a vehicle body connecting region (e.g., vehicle body connecting region 17c in the embodiment) that extends approximately horizontally from the lower end of the inclined region to the outer side in the second direction and connects to the skeletal member.

[0009] In the battery housing case of this aspect, when an impact load directed inward in the second direction is input to the vehicle body connection region of the main frame member through a frame member of the vehicle body, the load concentrates near the boundary between the vehicle body connection region and the inclined region of the upper wall of the main frame member. At this time, because the inclined region of the upper wall is inclined downward toward the outside in the second direction, the area near the boundary between the vehicle body connection region and the inclined region of the upper wall is displaced downward and bent into a concave shape. Therefore, the outer portion of the main frame member in the second direction does not rise significantly upward, and the impact load is transmitted inward in the second direction. As a result, the impact load is also transmitted effectively through the main frame member to the bottom wall member below the cross member. Therefore, in the battery housing case of this aspect, the impact load input from the frame member below the vehicle body can be efficiently absorbed not only by the cross member but also by the bottom wall member. Therefore, when the battery housing case of this aspect is adopted, it is possible to efficiently absorb the input impact load by parts other than the battery cells while suppressing an increase in the size of the cross member and an increase in the number of cross members installed.

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

[0011] In this case, because the bent ridgeline is located between the inclined region of the upper wall portion and the vehicle body connecting region, when an impact load is input from the outside of the main frame member in the second direction, the upper wall portion is likely to bend and deform in a concave downward shape starting from the bent ridgeline. Therefore, when this configuration is adopted, it is easier to obtain desirable deformation behavior of the upper wall portion that can effectively transmit the load from the main frame member to the bottom wall member.

[0012] The main skeleton member may further have a lower wall portion (e.g., lower wall portion 18 in the embodiment) that is arranged below the upper wall portion and that, together with the upper wall portion, forms a closed cross section along the first direction, and the end portion of the lower wall portion on the inner side in the second direction may be arranged at a height close to the bottom wall member.

[0013] In this case, the upper wall portion and the lower wall portion of the main frame member form a closed cross section along the first direction, so even if the upper wall portion is bent and deformed downwardly in a concave shape near the boundary between the body connection region and the inclined region, it is possible to efficiently transmit the impact load to the bottom wall member through the lower wall portion.

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

[0015] In this configuration, a first reinforcing rib is provided that slopes inward in the second direction downward from a position more inward in the second direction than the inclined region of the upper wall portion, and the first reinforcing rib connects the upper wall portion and the lower wall portion. Therefore, when an impact load directed inward in the second direction is input to the vehicle body connection region of the main frame member, a reaction force is applied from the first reinforcing rib to a position more inward in the second direction than the inclined region of the upper wall portion so as to prevent the end of the inward end of the inclined region in the second direction from collapsing downward. As a result, the upper wall portion is more likely to bend and deform downward in a concave shape near the boundary between the vehicle body connection region and the inclined region. In addition, in this configuration, since the first reinforcing rib is inclined downward and inward in the second direction, it becomes possible to effectively transmit a portion of the impact load transmitted to the end of the inclined region of the upper wall portion on the inner side in the second direction to the lower wall portion through the first reinforcing rib. Therefore, when this configuration is adopted, it becomes possible to effectively transmit the input impact load to the bottom wall member below the cross member through the main frame member.

[0016] Within the closed cross section of the main skeleton member, a second reinforcing rib (e.g., second reinforcing rib 22 in the embodiment) may be provided that slopes downward from a position outside the inclined region of the upper wall portion in the second direction toward the inside in the second direction, connecting the upper wall portion and the lower wall portion.

[0017] In this configuration, the second reinforcing rib, which is connected to a position further outward in the second direction than the inclined region of the upper wall portion, is inclined downward and inward in the second direction, making it possible to effectively transmit part of the impact load input to the vehicle body connection region to the lower wall portion 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 portion even before the area near the boundary between the vehicle body connecting area and the inclined area is significantly bent and deformed downward into a concave shape.

[0018] The upper wall portion may further include a base side horizontal region (for example, base side horizontal region 17a in the embodiment) extending approximately horizontally toward the inside in the second direction on the inside of the inclined region in the second direction.

[0019] In this case, because the base-side horizontal region is disposed inside the inclined region in the second direction, it is possible to prevent the portion of the upper wall portion that is inside the inclined region in the second direction from deforming earlier than the inclined region in the initial stage of input of the impact load. Therefore, when this configuration is adopted, it is possible to reliably cause bending deformation near the boundary between the vehicle body connecting region and the inclined region first in the initial stage of input of the impact load.

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

[0021] In this case, since the bottom wall member has a highly rigid multiple wall structure, it is possible for the bottom wall member to reliably receive the impact load input through the main frame member.

[0022] The main skeleton member is connected to the cross member and the bottom wall member on the inner side in the second direction, and further has a hollow base frame portion (e.g., base frame portion 15 in the embodiment) that stands upward from a height position connected to the bottom wall member, and it is desirable that the upper wall portion and the lower wall portion are connected to the outer side of the base frame portion in the second direction, and that the upper wall portion is connected to the center position in the height direction of the base frame portion or a position slightly below the center position.

[0023] In this case, because the upper wall portion is connected to the base frame portion at a height center position or a position slightly below the center position, the impact load transmitted from the upper wall portion to the base frame portion can be transmitted more effectively to the bottom wall member. Furthermore, in the later stage of the impact load input, the base frame portion can be effectively deformed by the load input from the upper wall portion to the base frame portion. Therefore, the energy of the impact load can be absorbed by the deformation of the base frame portion. [Effects of the Invention]

[0024] The battery housing case according to the present invention can efficiently absorb input impact loads by portions other than the battery cells while avoiding an increase in the overall size and weight. Therefore, when the battery housing case according to the present invention is adopted, the overall size and weight of the battery housing case can be reduced, thereby contributing to improved energy efficiency of the vehicle. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a cross-sectional view showing a structure of a lower part of a vehicle body of an embodiment; [Figure 2] FIG. 2 is a perspective view of a battery housing case according to the embodiment. [Figure 3] FIG. 2 is an exploded perspective view of the battery housing case according to the embodiment. [Figure 4] FIG. 2 is a cross-sectional view of a portion of the battery housing case according to the embodiment. [Figure 5] 4 is a cross-sectional view illustrating load transmission in the battery housing case according to the embodiment. FIG. [Figure 6] 10 is a cross-sectional view illustrating load transmission in a battery housing case according to a modified example. [Figure 7] FIG. 10 is a cross-sectional view illustrating load transmission in a battery housing case according to another modified example. [Figure 8] FIG. 10 is a cross-sectional view illustrating load transfer in a battery housing case according to still another modified example. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, an arrow FR pointing forward of the vehicle, an arrow UP pointing upward of the vehicle, and an arrow LH pointing to the left side of the vehicle are indicated at appropriate locations. In the following embodiments and their modifications, common parts are designated by the same reference numerals, and redundant explanations will be omitted.

[0027] Fig. 1 is a diagram showing the underbody structure of a vehicle 1. Fig. 1 is a cross-sectional view of the underbody of the vehicle 1 cut in a direction perpendicular to the longitudinal direction of the vehicle body. A pair of side sills 3, which are frame members of the vehicle body and extend substantially along the longitudinal direction of the vehicle body, are disposed at lower positions on both sides of the vehicle interior 2 in the vehicle width direction. Only one of the side sills 3 is shown in FIG. 1 . Floor panels 4 are mounted on the left and right side sills 3. A battery housing case 10 is disposed below the floor panel 4 so as to substantially follow the underside of the floor panel 4. The battery housing case 10 includes a case main body 25 on the upper side of which a plurality of battery cells 6 and control devices (not shown) are mounted, and a cover member 30 that covers the upper side of the case main body 25. The case body 25 is formed in a substantially rectangular shape in a plan view. 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 FIGS. 4 and 5).

[0028] The side sill 3 is configured 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 upper and lower joining flanges 3Af, 3Bf. The upper and lower joining flanges 3Af, 3Bf of the side sill inner 3A and the side sill outer 3B are arranged opposite each other. The mutually opposing joining flanges 3Af, 3Bf are connected by welding or the like with the stiffener 3C sandwiched between them. The side sill inner panel 3A has an inner bulge portion 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, 3Bf. The left and right side edges of the case body 25 are fixed to the underside of the inner bulge portion 3Ac of the side sill inner panel 3A.

[0029] Fig. 2 is a perspective view of the battery housing case 10, and Fig. 3 is an exploded perspective view of the battery housing case 10. Note that the cover member 30 is omitted in Figs. The case body 25 of the battery housing case 10 includes a pair of main skeleton members 11 that extend substantially along the fore-and-aft direction of the vehicle body. The pair of main skeleton members 11 are spaced apart in the vehicle width direction. The pair of main skeleton members 11 are connected by a first cross member 12f, a second cross member 12s, and a third cross member 12t that extend along the vehicle width direction. Both ends of the first cross member 12f in the extension direction are connected to the front ends of the left and right main skeleton members 11, and both ends of the second cross member 12s in the extension direction are connected to the rear ends of the left and right main skeleton members 11. Furthermore, both ends of the third cross member 12t in the extension direction are connected to approximately the center of the left and right main skeleton members 11 in the fore-and-aft direction.

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

[0031] The case body 25 further includes a bottom wall member 13 that covers the lower space between the pair of main frame members 11. The bottom wall member 13 is rectangular in plan view, and the pair of main frame members 11 and the lower ends of the first, second, and third cross members 12f, 12s, and 12t are coupled to its upper surface. A plurality (four) of battery units 7 (a plurality of battery cells 6) are mounted on the upper surface of the bottom wall member 13. Two battery units 7 are mounted side by side in the vehicle width direction on the upper surface of the front side of the bottom wall member 13, sandwiching the third cross member 12t therebetween, and the remaining two battery units 7 are similarly mounted side by side in the vehicle width direction on the upper surface of the rear side of the bottom wall member 13, sandwiching the third cross member 12t therebetween. The battery units 7 (a plurality of battery cells 6) housed in the case body 25 are surrounded on the outside by the pair of main frame members 11 and the first, second, and third cross members 12f, 12s, and 12t. Each battery unit 7 housed in the case body 25 is disposed at a distance from the adjacent main skeleton members 11 so as not to come into contact with the adjacent main skeleton members 11. In other words, a space is provided between the left and right main skeleton members 11 and the adjacent battery unit 7.

[0032] The bottom wall member 13 includes a base wall 7b facing the housing portion of the battery unit 7 and a flow path forming wall 7f joined to the lower surface of the base wall 7b. The flow path forming wall 7f forms a coolant flow path 14 for flowing coolant inside between the base wall 7b and the lower surface of the base wall 7b. The multiple battery cells 6 housed in the battery housing case 10 are cooled by flowing coolant through the coolant flow path 14. The bottom wall member 13 of this embodiment has a multi-wall structure with a hollow space therein, which is made up of a base wall 7b and a flow path forming wall 7f below it.

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

[0034] An equipment mounting frame 8 is installed on top 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 so as to straddle the front and rear above the central region of the vehicle width direction of the four battery units 7. Control equipment and their wiring (not shown) are mounted on the top of the equipment mounting frame 8.

[0035] In this embodiment, the vehicle body 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 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 are connected at both ends in the extension direction to each main frame member 11. 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] Fig. 4 is a cross-sectional view of a portion of the battery housing case 10. Fig. 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 skeleton member 11 has a hollow base frame portion 15 on its inner surface in the vehicle width direction to which the extending ends of the first, second, and third cross members 12f, 12s, and 12t are connected, 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 portion 15 has a cross section perpendicular to the longitudinal direction of the vehicle body, which is formed in a vertically long rectangular shape. The rectangular cross section of the base frame portion 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 a center 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 disposed at a height position close to the bottom wall member 13 (approximately the same height as the bottom wall member 13). The outer ends in the vehicle width direction of the upper wall portion 17 and the lower wall portion 18 are closed by end walls 19 that stand up approximately vertically. The mounting frame portion 16 has a horizontally elongated, substantially rectangular closed cross section formed by the outer side wall of the base frame portion 15 in the vehicle width direction, an upper wall portion 17, a lower wall portion 18, and an end wall 19. This closed cross section extends in the fore-and-aft direction of the vehicle body. In this embodiment, the upper wall portion 17 is connected to the center position c1 in the height direction of the base frame portion 15, but the connection position of the upper wall portion 17 with respect to the base frame portion 15 may be a position slightly lower than the center 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 disposed at a height higher than the bottom wall member 13. The upper wall portion 17 includes a base-side horizontal region 17a extending substantially horizontally from the side wall of the base frame portion 15 outward in the vehicle width direction, an inclined region 17b sloping downward from the outer end of the base-side horizontal region 17a outward in the vehicle width direction, and a vehicle body connecting region 17c extending substantially horizontally from the lower end of the inclined region 17b outward in the vehicle width direction and connected to the lower surface of the inner bulge portion 3Ac of the side sill 3. A curved ridgeline 20 extending along the fore-and-aft direction of the vehicle body is disposed 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 sloping gently upward from the outer end of the base-side region 18a in the vehicle width direction, and an outer extending region 18c extending substantially horizontally outward in the vehicle width direction from the upper end of the gently sloping region 18b. An end of the outer extending region 18c of the lower wall portion 18 and an end of the vehicle body connecting region 17c of the upper wall portion 17 are connected by an end wall 19.

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

[0041] Furthermore, within the closed cross section of the mounting frame portion 16 (main skeleton member 11), a second reinforcing rib 22 is provided that slopes downward and inward in the vehicle width direction from a position (a position in the vehicle body connecting region 17c close to the sloped region 17b) outer than the sloped region 17b of the upper wall portion 17. The second reinforcing rib 22 has an upper end connected to the upper wall portion 17 and a lower end connected to the boundary between the outer extending region 18c and the gently sloping region 18b of the lower wall portion 18.

[0042] Based on this, we will explain the deformation behavior of the battery housing case 10 and the load transmission at that time when the battery housing case 10 containing the battery cells 6 (battery units 7) is attached to the vehicle 1 and an impact load is input from the side of the vehicle body in this state.

[0043] FIG. 5 is a cross-sectional view for explaining load transmission of the battery housing case 10. As shown in FIG. As shown in FIGS. 4 and 5 , when an impact load F is input from the side of the vehicle 1, the impact load F is transmitted to the vehicle body connecting region 17c of the main frame member 11 of the battery housing 10 through one of the left and right side sills 3. When a load directed toward the inside in the vehicle width direction is input to the vehicle body connecting region 17c of the main frame member 11, the load is concentrated near the boundary between the vehicle body connecting region 17c and the inclined region 17b of the upper wall portion 17 (bent ridge line 20). At this time, because the inclined region 17b of the upper wall portion 17 is inclined downward toward the outside in the vehicle width direction, the area near the boundary between the vehicle body connecting region 17c and the inclined region 17b of the upper wall portion 17 is bent and deformed into a concave shape while being displaced downward, as shown by the imaginary line in FIG. 4 . As a result, the outer portion of the main frame member 11 in the vehicle width direction is not significantly lifted upward, and the impact load F is transmitted toward the inside in the vehicle width direction. Therefore, many components of the impact load are transmitted from the main frame member 11 to the bottom wall member 13, which has high rigidity.

[0044] At the initial stage of input of the impact load F, as described above, the upper wall portion 17 near the boundary between the vehicle body connecting region 17c and the inclined region 17b bends downward, while the vehicle width directional outer portion of the mounting frame portion 16 is crushed and deformed while rotating inward in the vehicle width direction together with the side sill 3, with the bent portion as a fulcrum. At this time, the upper wall portion 17 of the mounting frame portion 16 is supported by the first reinforcing rib 21 in a portion more inward in the vehicle width direction than the inclined region 17b, and the first reinforcing rib 21 is inclined downward and inward in the vehicle width direction. Therefore, the downward collapse of the portion of the upper wall portion 17 more inward in the vehicle width direction than the inclined region 17b is restricted by the first reinforcing rib 21. Therefore, the bending deformation of the upper wall portion 17 near the boundary between the vehicle body connecting region 17c and the inclined region 17b progresses more reliably.

[0045] Furthermore, most of the component forces of the impact load F input to the vehicle body connecting region 17c on the upper wall portion 17 side of the mounting frame portion 16 are transmitted to the lower wall portion 18 through the second reinforcing rib 22 and the first reinforcing rib 21. The numbers shown within the arrows in Fig. 5 indicate the proportion of the load transmitted to each part of the upper wall portion 17 and the lower wall portion 18, and the proportion of the load transmitted to the cross member (e.g., the third cross member 12t) and the bottom wall member 13, when the impact load input to the vehicle body connecting region 17c is set to "10".

[0046] As described above, in the battery housing case 10 of this embodiment, the main skeleton member 11 has the upper wall portion 17 disposed at a height higher than the bottom wall member 13, and the upper wall portion 17 includes the inclined region 17b and the vehicle body connecting region 17c. The inclined region 17b is inclined downward from the inside toward the outside in the vehicle width direction, and the vehicle body connecting region 17c extends substantially horizontally from the lower end of the inclined region 17b toward the outside in the vehicle width direction and is connected to the side sill 3, which is a vehicle skeleton member. Therefore, when an impact load directed toward the inside in the vehicle width direction is input to the vehicle body connecting region 17c of the main skeleton member 11 through the side sill 3 on the side of the vehicle, the vicinity of the boundary between the vehicle body connecting region 17c and the inclined region 17b of the upper wall portion 17 is displaced downward and bent into a concave shape. As a result, when an impact load is input, the outer portion of the main frame member 11 in the vehicle width direction does not rise significantly upward, and the input load can be transmitted well through the main frame member 11 to the bottom wall member 13 below 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. Therefore, when the battery housing case 10 of this embodiment is used, the input impact load can be efficiently absorbed by portions other than the battery cells 6, while suppressing an increase in the size of the cross members and an increase in the number of cross members installed.

[0047] Furthermore, the battery housing case 10 of this embodiment has a curved ridgeline 20 extending along the front-rear direction of the vehicle body between the inclined region 17b and the vehicle body connecting region 17c of the upper wall portion 17 of the main frame member 11. Therefore, when an impact load is input from the outside in the vehicle width direction of the main frame member 11, the upper wall portion 17 is likely to bend and deform in a concave shape downward starting from the curved ridgeline 20. Therefore, when this configuration is adopted, it is easy to obtain desirable deformation behavior of the upper wall portion 17 that can effectively transmit the load from the main frame member 11 to the bottom wall member 13.

[0048] Furthermore, in the battery housing case 10 of this embodiment, the main frame member 11 has an upper wall portion 17 and a lower wall portion 18, which form a closed cross section along the fore-and-aft direction of the vehicle body. The inner end of the lower wall portion 18 in the vehicle width direction is located at a height close to the bottom wall member 13 (approximately the same height as the bottom wall member 13). Therefore, even if the boundary between the vehicle body connecting region 17c and the inclined region 17b of the upper wall portion 17 is bent and deformed downward into a concave shape when an impact load is input, the impact load can be efficiently transmitted to the bottom wall member 13 through the lower wall portion 18.

[0049] Furthermore, in the battery housing case 10 of this embodiment, a first reinforcing rib 21 is provided within the closed cross section of the main frame member 11. The first reinforcing rib 21 slopes inward in the vehicle width direction from a position more inward in the vehicle width direction than the inclined region 17b of the upper wall portion 17 downward, 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 input to the vehicle body connecting region 17c of the main frame member 11, a reaction force acts from the first reinforcing rib 21 to prevent the vehicle widthwise inner end of the inclined region 17b from collapsing downward. At this time, because the first reinforcing rib 21 slopes inward in the vehicle width direction from a position more inward in the vehicle width direction than the inclined region 17b downward, the upper side does not collapse inward in the vehicle width direction under the load, and the vehicle widthwise inner end of the inclined region 17b can be prevented from collapsing downward. As a result, the upper wall portion 17 is more likely to bend and deform in a concave shape downward near the boundary between the vehicle body connecting region 17c and the inclined region 17b. In addition, 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 end of the inclined region 17b of the upper wall portion 17 on the inner side in the vehicle width direction can be transmitted well 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 bottom wall member 13 below the cross members 12f, 12s, and 12t.

[0050] Furthermore, in the battery housing case 10 of this embodiment, a second reinforcing rib 22 is provided within the closed cross section of the main frame member 11. The second reinforcing rib 22 slopes downward from a position further outward in the vehicle width direction than the inclined region 17b of the upper wall portion 17 and inward in the vehicle width direction, and the second reinforcing rib 22 is connected to the upper wall portion 17 and the lower wall portion 18. This allows a portion of the impact load input to the vehicle body connecting region 17c to be effectively transmitted to the lower wall portion 18 via the second reinforcing rib 22. Therefore, even before the vicinity of the boundary between the vehicle body connecting region 17c and the inclined region 17b is significantly bent and deformed downward into a concave shape, the load can be efficiently transmitted to the bottom wall member 13 via the second reinforcing rib 22 and the lower wall portion 18.

[0051] FIG. 6 is a cross-sectional view similar to FIG. 5, showing a modified example in which the first reinforcing rib 21A and the second reinforcing rib 22A are raised vertically without being inclined inward in the vehicle width direction from their upper ends to their lower ends. In the case of this modified example, the first reinforcing rib 21A and the second reinforcing rib 22A are not inclined inward in the vehicle width direction from their upper ends to their lower ends, and therefore, as is clear from the numbers indicating the load sharing ratios indicated within the arrows in Fig. 6, the load cannot be transmitted to the bottom wall member 13 as efficiently as in the embodiment shown in Figs. 4 and 5. In the embodiment shown in Figs. 4 and 5, the first reinforcing rib 21A and the second reinforcing rib 22A are inclined inward in the vehicle width direction from their upper ends to their lower ends, and therefore the input impact load can be transmitted to the bottom wall member 13 efficiently.

[0052] Furthermore, the battery housing case 10 of this embodiment is provided with a base-side horizontal region 17a that extends substantially horizontally toward the inside in the vehicle width direction, on the inside in the vehicle width direction of the inclined region 17b of the upper wall portion 17. This makes it possible to prevent the portion of the upper wall portion 17 that is closer to the inside in the vehicle width direction than the inclined region 17b from deforming early in the initial stage of input of an impact load. Therefore, when this configuration is employed, it is possible to ensure that the vicinity of the boundary between the vehicle body connecting region 17c and the inclined region 17b bends and deforms first in the initial stage of input of an impact load.

[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 portion. Therefore, when the battery housing case 10 of this embodiment is used, the impact load input through the main frame member 11 can be reliably received by the bottom wall member 13 of the multi-wall structure, which has high rigidity in the horizontal direction.

[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 skeleton member 11 is connected to the bottom wall member 13. The inside of the base frame portion 15 in the vehicle width direction is connected to the cross members 12f, 12s, and 12t and the bottom wall member 13. The upper wall portion 17 and the lower wall portion 18 of the main skeleton member 11 are connected to the outside of the base frame portion 15 in the vehicle width direction, and the upper wall portion 17 is connected to the center position c1 of the base frame portion 15 in the height direction or a position slightly below the center 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 transmitted more efficiently to the bottom wall member 13. Furthermore, in the later stage of the impact load input, the load input from the upper wall portion 17 to the base frame portion 15 can effectively deform the base frame portion 15. That is, a load is applied from the upper wall portion 17 to the approximate center position in the height direction of the hollow base frame portion 15, thereby allowing the base frame portion 15 to be deformed satisfactorily. Therefore, when this configuration is adopted, the deformation of the base frame portion 15 makes it possible to efficiently absorb the energy of the impact load.

[0055] Fig. 7 is a cross-sectional view similar to Fig. 5, showing a modified example in which the upper wall portion 17 of the main skeleton member 11 is connected above the center position c1 in the height direction of the base frame portion 15. Fig. 8 is a cross-sectional view similar to Fig. 5, showing another modified example in which the upper wall portion 17 of the main skeleton member 11 is connected to the upper end portion of the base frame portion 15. In these modified examples, a base-side inclined region 17aA is arranged on the inner side in the vehicle width direction of the inclined region 17b, and an end portion 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 the base frame portion 15 at a position above the center position c1 in the height direction, and therefore, as is clear from the numbers indicating the load sharing ratios 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 embodiment shown in Figures 4 and 5. In the embodiment shown in Figures 4 and 5, the upper wall portion 17 is connected to the base frame portion 15 at the center position c1 in the height direction or at a position slightly below the center position c1, and therefore the input impact load can be transmitted to the bottom wall member 13 efficiently.

[0056] The present invention is not limited to the above-described embodiment, and various design modifications are possible without departing from the spirit of the present invention. For example, in the above-described embodiment, three cross members are provided spaced apart in the front-rear direction and connected to the 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 less.

[0057] In the above embodiment, the pair of main frame members 11 extend along the vehicle body longitudinal direction 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 the cross members is not limited to this. For example, the pair of main frame members may extend along the vehicle width direction and be spaced apart from each other in the vehicle body longitudinal direction, and the cross members may be arranged along the vehicle body longitudinal direction.

[0058] In the above embodiment, the bottom wall member 13 has a multi-wall structure made up of the base wall 7b and the flow path forming wall 7f, but the multi-wall structure is not limited to this. The bottom wall member 13 may have a multi-wall structure made of a dedicated member separate from the coolant flow path 14. It is not essential that the bottom wall member 13 has a multi-wall structure, and the bottom wall member 13 may have a structure with high rigidity in the horizontal direction. [Explanation of symbols]

[0059] 3...Side sill (framework) 6...Battery cell 10...Battery storage case 11...Main frame member 12f...First cross member (cross member) 12s...Second cross member (cross member) 12m...Third cross member (cross member) 13...Bottom wall member 15...Base frame part 17...Top wall part 17a…Base side horizontal area 17b…Slope area 17c...Car body connection area 18…Lower wall part 20...Bend ridge 21, 21A...First reinforcing rib 22, 22A...Second reinforcing rib

Claims

1. A battery housing case attached to a frame member under a vehicle body and housing a battery cell therein, a pair of main skeletal members extending along a first direction intersecting a vertical direction and spaced apart from each other in the first direction and a second direction intersecting the vertical direction; a cross member extending along the second direction and having both ends in the extending direction connected to each of the main frame members; a bottom wall member connected to each of the main frame members to cover a lower space between the pair of main frame members, and on whose upper surface the battery cell is placed; the main frame member has an upper wall portion that is located at a height higher than the bottom wall member, The upper wall portion of the battery storage case is characterized in that it has an inclined region that slopes downward from the inside of the second direction, which is the side closest to the cross member in the second direction, to the outside of the second direction, which is the side away from the cross member, and a vehicle body connection region that extends approximately horizontally from the lower end of the inclined region to the outside of the second direction and is connected to the skeletal member.

2. The battery case according to claim 1 , wherein a curved ridgeline extending along the first direction is disposed between the inclined region of the upper wall portion and the vehicle body connecting region.

3. the main skeleton member further includes a lower wall portion disposed below the upper wall portion and forming, together with the upper wall portion, a closed cross section along the first direction; 2. The battery case according to claim 1, wherein an inner end of the lower wall portion in the second direction is disposed at a height close to the bottom wall member.

4. 4. The battery housing case according to claim 3, wherein a first reinforcing rib is provided within the closed cross section of the main skeleton member, the first reinforcing rib inclining inward in the second direction downward from a position more inward in the second direction than the inclined region of the upper wall portion and connecting the upper wall portion and the lower wall portion.

5. 5. The battery housing case according to claim 4, wherein a second reinforcing rib is provided within the closed cross section of the main skeleton member, the second reinforcing rib inclining downward from a position outside the inclined region of the upper wall portion in the second direction toward the inside in the second direction, and connecting the upper wall portion and the lower wall portion.

6. The battery case according to claim 5, wherein the upper wall portion further includes a base-side horizontal region extending substantially horizontally inward in the second direction on the inside of the inclined region.

7. 2. The battery case according to claim 1, wherein the bottom wall member has a multi-wall structure having a hollow portion.

8. the main frame member is connected to the cross member and the bottom wall member at an inner side in the second direction, and further includes a hollow base frame portion standing upward from a height position connected to the bottom wall member, the upper wall portion and the lower wall portion are connected to the outer side of the base frame portion in a second direction, 4. The battery case according to claim 3, wherein the upper wall portion is connected to the base frame portion at a center position in the height direction or at a position slightly below the center position.

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