Battery case for vehicle

Abstract

This battery case for vehicle has a housing part for housing a battery cell. A lower part of the battery case for vehicle has a pair of first frame parts extending in a vehicle width direction and constituting both end parts in a vehicle front-and-rear direction, and a pair of second frame parts which are skeleton members extending in the vehicle front-and-rear direction. Of the first frame parts and the second frame parts, only the pair of first frame parts are formed by die casting.

Description

Battery case for vehicle

[0001] The present invention relates to a battery case for a vehicle.

[0002] Patent Document 1 discloses a vehicle battery case that increases the strength of the battery case of an electric vehicle to improve collision performance. The battery case of Patent Document 1 comprises, on a case side wall facing outward in the vehicle width direction: at least two fixing portions that protrude outward in the vehicle width direction and are fixed to the vehicle body; and a connecting wall formed in a surface shape opposing the case side wall and connecting the at least two fixing portions in the front-rear direction. The fixing portions and the connecting wall are coupled in the front-rear direction to both side surfaces of a floor panel formed integrally with the battery case, and the fixing portions and the connecting wall are integrally formed on a metal die-cast battery case.

[0003] Japanese Unexamined Patent Publication No. 2020-35554

[0004] The invention of Patent Document 1 is intended to inexpensively form a configuration that effectively absorbs collision energy while reducing the number of parts by integrally molding the two fixing portions and the connecting wall in the metal die-cast battery case. However, since the entire battery case is made of metal die-cast, there are problems that the weight of the entire battery case increases, a large mold is required to manufacture the battery case, and the initial cost becomes extremely high. There is also another problem that the amount of collision energy absorbed by the battery case may not be sufficient.

[0005] Therefore, an object of the present invention is to provide a vehicle battery case that can suppress manufacturing costs and initial costs, allow a part of the battery case to have a complex shape adapted to the vehicle body structure, and also increase the rigidity of the battery case.

[0006] The present invention comprises the following configuration: [1] A vehicle battery case having a housing portion for housing battery cells, wherein the lower part of the vehicle battery case has a pair of first frame portions extending in the vehicle width direction and constituting both ends in the vehicle front-rear direction, and a pair of second frame portions which are skeletal members extending in the vehicle front-rear direction, and of the first frame portions and the second frame portions, only the pair of first frame portions are formed by die-casting.

[0007] According to the present invention, by combining a die-cast first frame portion that constitutes at least one of the front-rear ends with a second frame portion that is a skeletal member extending in the front-rear direction, the front-rear ends of the battery case can be made into a complex shape that corresponds to the available space in the vehicle structure, while also ensuring the rigidity of the battery case. Furthermore, since the die-cast members can be made smaller, the weight of the battery case can be kept low, initial costs can be reduced, and design changes can be easily made.

[0008] Figure 1 is a perspective view of the vehicle structure according to this embodiment, viewed from below. Figure 2 is a bottom view of the vehicle structure, viewed from below. Figure 3 is a bottom view showing the battery case installed in Figure 2. Figure 4 is a top view of the vehicle structure, viewed from above. Figure 5 is a bottom perspective view showing the battery case removed. Figure 6 is a bottom perspective view showing the battery case installed. Figure 7 is a stepped cross-sectional view taken along line A-A in Figure 3, showing the battery case mounting structure. Figure 8 is a perspective view of the battery case with the cover omitted. Figure 9 is a bottom view of the battery case. Figure 10 is a cross-sectional view taken along line B-B in Figure 9, showing only the rear of the first frame and the bottom plate.

[0009] Embodiments of the present invention will be described in detail below with reference to the drawings. In the following drawings, the symbol FR indicates the front of the vehicle, the symbol UP indicates the top of the vehicle, and the symbol LH indicates the left side in the vehicle width direction (left side in the direction of travel). The opposite direction of symbol FR is the rear of the vehicle, the opposite direction of symbol UP is the bottom of the vehicle, and the opposite direction of symbol LH is the right side in the vehicle width direction (right side in the direction of travel). Hereinafter, these directions may simply be referred to as front, rear, top, bottom, left side, and right side.

[0010] Figure 1 is a perspective view of the vehicle structure according to this embodiment, viewed from below. Figure 2 is a bottom view of the vehicle structure, viewed from below. Figure 3 is a bottom view showing the vehicle structure with the battery case installed, as in Figure 2. Figure 4 is a top view of the vehicle structure, viewed from above. Figure 5 is a bottom perspective view showing the vehicle structure with the battery case removed. Figure 6 is a bottom perspective view showing the vehicle structure with the battery case installed.

[0011] The vehicle structure 1 according to this embodiment is not limited to any type of automobile to which it can be applied, as long as it is a structure that supports a vehicle battery case (hereinafter simply referred to as a battery case) 50. For example, it may be a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or an electric vehicle (BEV).

[0012] As shown in Figures 1 to 4, the vehicle structure 1 includes a dash panel 3 located at its front, a floor pan 5 located behind the dash panel 3, and a pair of side sills 9 provided at both ends of the floor pan 5 in the vehicle width direction.

[0013] The dash panel 3 is a partition plate that separates the passenger compartment from the front area of ​​the passenger compartment (e.g., the engine compartment) at the front end of the passenger compartment, and is formed, for example, by pressing a steel plate. The rear end of the dash panel 3 is connected to the front end of the floor pan 5, and it has a curved shape that goes upward as it moves forward from the rear end.

[0014] The floor pan 5 is a plate material that constitutes the lower part of the passenger compartment, and is formed, for example, by pressing a steel plate. The front end of the floor pan 5 is connected to the rear end of the dash panel 3 and extends almost horizontally towards the rear of the vehicle. As shown in Figures 1 to 4, a tunnel-shaped backbone 7 is provided in the center of the floor pan 5 in the vehicle width direction, projecting upward and extending in the front-rear direction.

[0015] A pair of side sills 9 extend in the longitudinal direction at both ends of the floor pan 5 in the vehicle width direction. As shown in Figure 1, the lower part of the front pillar 8 is connected to the front end of each of the pair of side sills 9.

[0016] Vehicle structure 1 has a front section 1A and a rear section 1B, and a battery case 50 is supported on its underside. The front section 1A of vehicle structure 1 includes a dash cross member 11, a backbone cross member 12, a pair of front side members 13, and a pair of front stringers 14. The rear section 1B of vehicle structure 1 includes a first rear cross member 31, a second rear cross member 32, a pair of rear side members 33, and a pair of rear stringers 34. The battery case 50 is attached and fixed to the frame constituting vehicle structure 1 via brackets 41, 43, 45, and 47, which will be described later.

[0017] (Front part 1A of vehicle structure 1) As shown in Figures 1 to 4, the front part 1A of the vehicle structure 1 includes a dash cross member 11 as a first cross member extending in the vehicle width direction, a backbone cross member 12 as a second cross member positioned behind the dash cross member 11 and extending in the vehicle width direction, a pair of front side members 13 positioned spaced apart from each other in the vehicle width direction and extending in the longitudinal direction to connect the dash cross member 11 and the backbone cross member 12, a front stringer 14 as a connecting member positioned between the pair of front side members 13 in the vehicle width direction and extending in the longitudinal direction to connect the dash cross member 11 and the backbone cross member 12, and a battery case 50 for housing the battery. By adopting such a structure for the front part 1A, in the event of a frontal collision, the collision energy (hereinafter also referred to as load) input to the pair of front side members 13 on the outer side in the vehicle width direction can be distributed to the front stringer 14 on the inner side in the vehicle width direction via the dash cross member 11. In this way, the load from the front can be transmitted to the backbone cross member 12 via multiple paths. Therefore, even when an impact is applied from the front of the vehicle, the collision energy can be efficiently distributed, and localized load concentration can be suppressed.

[0018] The dash cross member 11 is welded to the dash panel 3 and extends in the vehicle width direction to connect a pair of front side members 13, 13 that are spaced apart in the vehicle width direction.

[0019] The backbone cross member 12 has a hat-shaped cross section extending in the vehicle width direction and is welded and fixed to the lower surface 5a of the floor pan 5. The backbone cross member 12 has a projection 12a that protrudes upward along the backbone 7, and a pair of base portions 12b, 12b that extend from both ends of the projection 12a in the vehicle width direction to both sides in the vehicle width direction. The projection 12a is welded to the lower surface 7a of the backbone 7, and the pair of base portions 12b, 12b are welded to the lower surface 5a of the floor pan 5 on both sides of the backbone 7 in the vehicle width direction.

[0020] The widthwise ends of the backbone cross member 12 (i.e., the widthwise outer ends of the pair of bases 12b, 12b) are welded and connected to the inclined portions 13b, 13b of the pair of front side members 13, 13.

[0021] The front side member 13 has a hat-shaped cross-section extending in the front-rear direction, and its rear side is welded to the front surface 3b of the dash panel 3 and the lower surface 5a of the floor pan 5. The front side member 13 has a front-rear extension portion 13a that extends in the front-rear direction, and an inclined portion 13b that is connected to the rear end of the front-rear extension portion 13a and inclined outward in the vehicle width direction as it extends towards the rear.

[0022] The inclined portion 13b that constitutes the rear end of the front side member 13 extends rearward and outward in the vehicle width direction from the rear end of the longitudinal extension portion 13a and is welded and fixed to the front end of the side sill 9. In this way, the rear ends of the pair of front side members 13 are each connected to the front ends of the pair of side sills 9. Therefore, load can be transmitted from the pair of front side members 13 to the pair of side sills 9, increasing the load transmission paths and enabling load distribution.

[0023] The inclined portions 13b of the pair of front side members 13 are welded and connected to both ends of the backbone cross member 12 in the vehicle width direction. Therefore, load transmission in the vehicle width direction from the pair of front side members 13 to the backbone cross member 12 can be facilitated. Furthermore, load transmission in the vehicle width direction can also be made toward the pair of side sills 9 that are connected to the vehicle width direction outwards from both ends (inclined portions 13b) of the pair of front side members 13. In this way, load can be distributed from the pair of front side members 13 toward the vehicle width direction outwards and inwards.

[0024] (Rear part 1B of vehicle structure 1) As shown in Figures 1 to 4, the rear part 1B of vehicle structure 1 includes a first rear cross member 31 extending in the vehicle width direction, a second rear cross member 32 positioned in front of the first rear cross member 31 and extending in the vehicle width direction, a pair of rear side members 33 positioned spaced apart from each other in the vehicle width direction and extending in the longitudinal direction to connect the first rear cross member 31 and the second rear cross member 32, and a rear stringer 34 as a connecting member positioned between the pair of rear side members 33 in the vehicle width direction and extending in the longitudinal direction to connect the first rear cross member 31 and the second rear cross member 32. By adopting such a structure for the rear part 1B, in the event of a rear collision, the load applied to the pair of rear side members 33 on the outside in the vehicle width direction can be distributed to the rear stringer 34 on the inside in the vehicle width direction via the first rear cross member 31. In this way, the load from the rear can be transmitted to the second rear cross member 32 via multiple paths. Therefore, even when an impact is applied from the rear of the vehicle, the collision energy can be efficiently dispersed, suppressing localized load concentration.

[0025] The rear side member 33 has a hat-shaped cross-section extending in the front-rear direction and is welded to the lower surface 5a of the floor pan 5. The rear side member 33 has a front-rear extension portion 33a that extends in the front-rear direction and an inclined portion 33b that is connected to the front end of the front-rear extension portion 33a and inclined outward in the vehicle width direction as it extends forward.

[0026] The longitudinal extensions 33a of a pair of rear side members 33 are connected by a third rear cross member 35 and a fourth rear cross member 36, which are positioned behind the first rear cross member 31. The third rear cross member 35 and the fourth rear cross member 36 extend in the vehicle width direction, and both ends of these in the vehicle width direction are welded to the pair of longitudinal extensions 33a. The third rear cross member 35 and the fourth rear cross member 36 also have a hat-shaped cross section that extends in the vehicle width direction and are welded to the lower surface 5a of the floor pan 5. Furthermore, the longitudinal extensions 33a are provided with a suspension mounting portion 21 between the first rear cross member 31 and the third rear cross member 35, to which a suspension (not shown) is attached.

[0027] The inclined portions 33b of the pair of rear side members 33 extend forward and outward in the vehicle width direction from the front end of the longitudinal extension portion 33a and are welded and fixed to the rear end of the side sill 9. In this way, the front ends of the pair of rear side members 33 are each connected to the rear ends of the pair of side sills 9. Therefore, load can be transmitted from the pair of rear side members 33 to the pair of side sills 9, increasing the load transmission path.

[0028] As shown in Figures 3 and 5, the first rear cross member 31 and the second rear cross member 32 extend in the vehicle width direction, bridging the gap between the inclined portions 33b of the pair of rear side members 33, and have a hat-shaped cross section, and are welded to the lower surface 5a of the floor pan 5. Both ends of the first rear cross member 31 and the second rear cross member 32 in the vehicle width direction are connected to the inclined portions 33b of the pair of rear side members 33. Therefore, load transmission in the vehicle width direction from the pair of rear side members 33 towards the first rear cross member 31 and the second rear cross member 32 can be promoted. Furthermore, load transmission in the vehicle width direction can also be made towards the pair of side sills 9 connected to both ends (inclined portions 33b) of the pair of rear side members 33. This allows the load to be distributed from the pair of rear side members 33 to the outside and inside in the vehicle width direction.

[0029] As shown in Figures 5 and 6, the second rear cross member 32 has a cross central portion 32a on the vehicle width side to which the rear stringer 34 is connected, and cross end portions 32b that are bent downward at both ends in the vehicle width direction and connected to the inclined portions 33b of the rear side member 33. A ridge line 32c extending in the front-rear direction is formed at the boundary between the cross central portion 32a and the cross end portions 32b, and the second rear cross member 32 has a convex shape in which the center in the vehicle width direction protrudes upward in the vertical direction.

[0030] In this embodiment, a pair of rear stringers 34 are provided spaced apart in the vehicle width direction. The pair of rear stringers 34 extend in the front-rear direction to connect the first rear cross member 31 and the second rear cross member 32. The pair of rear stringers 34 have a hat-shaped cross section and are welded to the lower surface 5a of the floor pan 5. Note that the number of rear stringers 34 is not limited to a pair; there may be one or three or more.

[0031] The rear stringer 34 extends linearly in the front-rear direction when viewed from above. This allows for efficient transmission of the front-rear load applied during a front-end or rear-end collision from one of the first rear cross member 31 and the second rear cross member 32 to the other.

[0032] (Battery Case 50) Next, the specific configuration of the battery case 50 will be described based on Figure 3 and Figures 7 to 10. Figure 7 is a stepped cross-sectional view taken along line A-A of Figure 3, showing the mounting structure of the battery case. Figure 8 is a perspective view of the battery case with the cover omitted. Figure 9 is a bottom view of the battery case. Figure 10 is a cross-sectional view taken along line B-B of Figure 9, showing only the rear of the first frame and the bottom plate. Note that Figure 3 shows a battery case 50 for housing a battery (not shown).

[0033] The battery case 50 is a roughly rectangular parallelepiped case arranged along the lower surface 5a of the floor pan 5, and has housing sections 61, 62, and 63 for housing the battery and other control devices. The battery case 50 includes a first frame front section 51 extending in the vehicle width direction and forming the front end of the battery case 50, a first frame rear section 52 extending in the vehicle width direction and forming the rear end of the battery case 50, a pair of second frame sections 53 extending in the front-rear direction and connecting the vehicle width direction end of the first frame front section 51 and the vehicle width direction end of the first frame rear section 52, an internal side member 54, an internal cross member 55, a bottom plate 56, and a cover body 57. Note that in the battery case 50 shown in Figure 3, mainly the skeletal members 51, 52, 53, 54, and 55 are shown, and the bottom plate 56 and cover body 57 are not shown. The battery case 50 of this embodiment houses a battery for motor drive in plug-in hybrid vehicles, electric vehicles, etc., but the type of battery is not limited and may be, for example, a 12V battery.

[0034] The first frame front portion 51 is a component that constitutes the front end of the battery case 50 and is formed by die-casting metal. In this embodiment, aluminum is used, but any metal is acceptable and it is not limited to aluminum. The first frame front portion 51 extends in the vehicle width direction and is formed in a box shape with the top and rear open, and a rectangular front end housing portion 61 is formed which a control unit related to the battery and a cooling device are housed. The front end edge of the first frame front portion 51 has a front end portion 51a that extends in the vehicle width direction and a bent portion 51b that is bent in a crank shape toward the rear at both ends in the vehicle width direction. The rear end of the bent portion 51b is in contact with the front end of the second frame portion 53.

[0035] As shown in Figures 3 and 8, the front end portion 51a of the front part 51 of the first frame is provided with a pair of front central brackets 41 for fixing the battery case 50 to the backbone cross member 12. On the other hand, the bent portion 51b of the front part 51 of the first frame is provided with a front end bracket 43 for fixing the battery case 50 to the front side member 13.

[0036] The first frame rear portion 52 is a component that constitutes the rear end of the battery case 50, and like the first frame front portion 51, it is formed by die-casting metal. In this embodiment, aluminum is used, but any metal is acceptable and it is not limited to aluminum. The first frame rear portion 52 is a block-shaped component that extends in the vehicle width direction, and a rectangular rear end housing portion 62 is formed by cutting out a box-shaped notch toward the rear of the front and top surfaces of the central part in the vehicle width direction, thereby housing a control unit related to the battery, a cooling device, etc. The rear end edge of the first frame rear portion 52 is formed with a rear end portion 52a that extends in the vehicle width direction and inclined portions 52b at both ends in the vehicle width direction that incline toward the front.

[0037] As shown in Figures 3 and 8, a pair of rear central brackets 45 are provided at the rear end 52a of the rear portion 52 of the first frame for fixing the battery case 50 to the rear stringer 34. On the other hand, a rear end bracket 47 is provided at the inclined portion 52b of the rear portion 52 of the first frame for fixing the battery case 50 to the inclined portion 33b of the rear side member 33.

[0038] Furthermore, as shown in Figure 10, the rear portion 52 of the first frame has ribs 58 formed on the entire underside of the portion excluding the rear end housing portion 62. Multiple ribs 58 are arranged in a row in the front-rear direction and the vehicle width direction. This makes it possible to keep the weight low while maintaining high strength in the rear portion 52 of the first frame, which is formed into a block shape by die casting.

[0039] The internal side member 54 is a skeletal member that extends in the front-rear direction from the front part 51 of the first frame to the rear part 52 of the first frame inside the battery case 50. The internal side member 54 in the illustrated example includes a pair of first internal side members 54a and a second internal side member 54b. By providing such an internal side member 54, loads transmitted from the front to the battery case 50 can be transmitted to the rear via the internal side member 54. Furthermore, because a strong skeletal member such as the internal side member 54 is provided, the battery case 50 can function as part of the vehicle's skeletal structure.

[0040] The pair of first internal side members 54a are spaced apart from each other in the vehicle width direction and each extends in the front-rear direction, connected to the front end of the front end housing 61. The rear ends of the pair of first internal side members 54a are connected to the first internal cross member 55a, which will be described later.

[0041] The second internal side member 54b extends in the front-rear direction to connect the rear end of the rear end housing 62 with the first internal cross member 55a, which will be described later. The position of the second internal side member 54b in the vehicle width direction is not particularly limited, but in the illustrated example, it is positioned in the center of the battery case 50 in the vehicle width direction.

[0042] With this arrangement, the load applied to the internal side member 54 during a frontal or rearward collision of the vehicle is first distributed to both sides in the vehicle width direction by the first internal cross member 55a, which will be described later, thus increasing the load distribution effect. In addition, the reaction force of the lateral rigidity of the tire contact surface during steering can be received by the cross member of the frame and the battery case, thus improving steering stability. Furthermore, considering that the battery (not shown) is housed in multiple regions separated by the second internal side member 54b and the first to fourth internal cross members 55a to 55d, which will be described later, it is preferable from the viewpoint of space efficiency to position the second internal side member 54b in the center in the vehicle width direction.

[0043] The internal cross member 55 is a skeletal member that extends in the vehicle width direction within the battery case 50, bridging the gap between a pair of second frame sections. In the illustrated example, the internal cross member 55 includes first to fourth internal cross members 55a to 55d, which are arranged at predetermined intervals in the front-rear direction. The first to fourth internal cross members 55a to 55d are arranged in order from the front. By providing such an internal cross member 55, loads input to the battery case 50 from the outside in the vehicle width direction can be transmitted in the vehicle width direction via the internal cross member 55. Furthermore, because a robust skeletal member, the internal cross member 55, is provided, the battery case 50 can function as part of the vehicle's skeletal structure.

[0044] The first inner cross member 55a connects the rear ends of the pair of first inner side members 54a and the front end of the second inner side member 54b, and extends in the vehicle width direction so as to extend from the left end to the right end of the battery case 50. Accordingly, the load transmitted to the battery case 50 from the front can be transmitted in the order of the pair of first inner side members 54a, the first inner cross member 55a, and the second inner side member 54b, and then transmitted to the rear end of the battery case 50.

[0045] The vehicle width direction central portion of the second to fourth inner cross members 55b to 55d arranged rearward of the first inner cross member 55a is connected so as to intersect with the second inner side member 54b.

[0046] The first inner cross member 55a is arranged adjacent to the rear end of the first frame front portion 51 (front end accommodation portion 61), and the fourth inner cross member 55d is arranged adjacent to the front end of the first frame rear portion 52 (rear end accommodation portion 63). According to this configuration, the die-cast molded first frame front portion 51 and first frame rear portion 52 can be reinforced by the skeleton members.

[0047] As shown in FIGS. 7 to 9, the bottom plate 56 is a plate-shaped member that covers the entire lower surface of the outer edge of the battery case 50 defined by the first frame front portion 51, the first frame rear portion 52, and the pair of second frame portions 53. The bottom plate 56 is defined by the inner side members 54 and the inner cross members 55, and constitutes the bottom surface of the accommodation portion 63 that accommodates battery cells. As shown in FIG. 9, the bottom plate 56 covers the entire lower surface of the first frame rear portion 52 so as to cover the ribs 58 formed on the lower surface of the first frame rear portion 52.

[0048] As shown in FIG. 7, the cover body 57 is a member constituting the upper surface of the battery case 50. The cover body 57 comprises: a first cover body 57A that covers upper surfaces of accommodating portions 61, 62, and 63, and also serves as a bottom plate of a second accommodating portion 64 formed above the accommodating portions 61, 62, and 63; and a second cover body 57B that covers an upper side of an accommodated object such as a battery placed on an upper surface of the first cover body 57A. According to this configuration, the battery case 50 can be mounted with good space efficiency by stacking batteries in the vertical direction. At this time, the upper surface of the battery case 50 (the second cover body 57B) is formed along the upwardly convex curved second rear cross member 32.

[0049] The aforementioned battery case 50 is configured such that a front end portion and a rear end portion having a complex outer shape and accommodating portions 61 and 62 are constituted by a first frame front portion 51 and a first frame rear portion 52 formed by die casting, and a longitudinally intermediate portion constituting an accommodating portion 63 for accommodating battery cells is constituted by a second frame portion 53 formed of a frame-shaped skeleton member, an inner side member 54, and an inner cross member 55. This makes it possible to simultaneously achieve both extending the front and rear ends of the battery case 50 as much as possible according to the vehicle structure to secure a space for mounting battery-related high-voltage devices, and increasing the rigidity of the accommodation space for accommodating battery cells. Further, in the battery case 50, only the front and rear ends are frame portions formed by die casting, and a plurality of ribs 58 are formed, whereby an increase in weight can be suppressed as much as possible.

[0050] (Mounting structure of battery case 50) Next, a mounting structure of the battery case 50 will be described with reference to FIG. 3, FIG. 7, and the like. In the battery case 50, the second frame portion 53 extending in the front-rear direction overlaps a pair of side sills 9, the first frame front portion 51 overlaps a backbone cross member 12, and the first frame rear portion 52 overlaps a second rear cross member 32 described later and a pair of rear stringers 34.

[0051] The second frame portion 53 is a skeletal member that extends in the front-rear direction along the side sills 9, and is fixed to the pair of side sills 9 by a plurality of bolts 49 arranged at predetermined intervals in the front-rear direction. This allows the load applied to the pair of side sills 9 to be transmitted to and distributed to the battery case 50.

[0052] The center portion of the front part 51 of the first frame in the vehicle width direction is fixed to a pair of bases 12b of the backbone cross member 12 by a pair of front central brackets 41. Therefore, the load applied to the backbone cross member 12 can be transmitted to and distributed to the battery case 50.

[0053] The pair of front central brackets 41 overlap in the vehicle width direction with the pair of first internal side members 54a that constitute the battery case 50. As a result, the load applied to the front end of the battery case 50 via the pair of front central brackets 41 is efficiently transmitted to the pair of first internal side members 54a. The rear ends of the pair of first internal side members 54a are connected to the first internal cross member 55a, which will be described later.

[0054] More preferably, the positions in the vehicle width direction of the pair of front central brackets 41, the pair of first internal side members 54a, and the connection points between the pair of front stringers 14, 14 and the backbone cross member 12 all overlap and overlap when viewed from the front-rear direction. With such a positional relationship, load transmission to the first internal side members 54a via the front stringers 14, backbone cross member 12, and front central brackets 41 is performed efficiently.

[0055] The front portion 51 of the first frame is fixed to the inclined portions 13b of a pair of front side members 13 by a pair of front end brackets 43 on both sides in the vehicle width direction. Therefore, the load applied to the pair of front side members 13 can be transmitted to and distributed to the battery case 50. In particular, the inclined portion 13b of the front side member 13 is the base portion that connects to the side sill 9, so load tends to concentrate there. By fixing the battery case 50 to this inclined portion 13b, the load can be distributed to the battery case 50, and the concentration of load on the inclined portion 13b can be suppressed.

[0056] The front end bracket 43 is positioned behind the backbone cross member 12. This allows the collision load, which has been dispersed and weakened via the dash cross member 11, front stringer 14, backbone cross member 12, etc., to be transmitted to the battery case 50. This suppresses excessive load input to the battery case 50 and prevents damage to the battery.

[0057] The center portion of the rear 52 of the first frame in the vehicle width direction is fixed to the midpoint of the rear stringer 34 in the longitudinal direction by a pair of rear central brackets 45 attached to the pair of rear stringers 34. Therefore, the load applied to the rear side member 33 can be distributed and transmitted to the battery case 50 via the first rear cross member 31, the second rear cross member 32, and the rear stringer 34.

[0058] The rear portion 52 of the first frame is fixed to the inclined portions 33b of a pair of rear side members 33 by a pair of rear end brackets 47 on both sides in the vehicle width direction. Therefore, the load applied to the pair of rear side members 33 can be transmitted to and distributed to the battery case 50. In particular, the inclined portion 33b of the rear side member 33 is the base portion that connects to the side sill 9, so load tends to concentrate there. By fixing the battery case 50 to this inclined portion 33b, the load can be distributed to the battery case 50, and the concentration of load on the inclined portion 33b can be suppressed.

[0059] The rear end bracket 47 is positioned in front of the first rear cross member 31 and near the front of the second rear cross member 32. This allows the collision load, which has been dispersed and weakened via the rear side member 33, the first rear cross member 31, the second rear cross member 32, the rear stringer 34, etc., to be transmitted to the battery case 50. This suppresses excessive load input to the battery case 50 and prevents damage to the battery.

[0060] Furthermore, the rear end bracket 47 is positioned near the front of the second rear cross member 32, connecting the vehicle width direction end of the first frame rear portion 52 of the battery case 50 and the vehicle width direction end of the second rear cross member 32. In other words, the rear 1B of the vehicle structure 1 is formed by a second rear cross member 32 that extends in the vehicle width direction along its upper surface and whose center in the vehicle width direction is curved upward, the first frame rear portion 52 that constitutes the lower rear end of the battery case 50, and a pair of rear end brackets 47 that connect these vehicle width direction ends, forming an annular structure made of strong members. This configuration can be seen in Figure 7. As a result, by providing the battery case 50 in the rear 1B of the vehicle structure 1, the rigidity of the vehicle structure 1 can be efficiently increased. This allows for efficient protection of the battery case 50 against collision energy associated with vehicle collisions, as well as external forces input from the suspension mounting portion 21 to the rear side member 33.

[0061] As described above, the following matters are disclosed in this specification: (1) A vehicle battery case having a housing for housing battery cells, wherein the lower part of the vehicle battery case has a pair of first frame parts extending in the vehicle width direction and constituting both ends in the vehicle longitudinal direction, and a pair of second frame parts which are skeletal members extending in the vehicle longitudinal direction, and of the first frame parts and the second frame parts, only the pair of first frame parts are formed by die casting. With this configuration, by combining the die-cast first frame parts and the skeletal second frame parts, the longitudinal ends of the battery case can be made into a complex shape corresponding to the available space in the vehicle structure, and the rigidity of the battery case can also be ensured. Furthermore, since the die-cast members can be made smaller, the weight of the battery case can be kept low, initial costs can be reduced, and design changes can be made easily.

[0062] (2) The vehicle battery case according to (1), wherein the first frame portion has an end housing portion formed adjacent to the housing portion formed between the pair of second frame portions. With this configuration, since the end housing portion is formed on the die-cast first frame portion, the design of the position and shape of the end housing portion becomes easier.

[0063] (3) The vehicle battery case according to (2), wherein the first frame portion has edges that extend in the vehicle width direction and form a front end and a rear end, and the edges have bent portions at both ends in the vehicle width direction that bend toward the vehicle longitudinal direction. With this configuration, the rigidity of the first frame portion is improved.

[0064] (4) The vehicle battery case according to (3), wherein the first frame portion has a plurality of ribs extending vertically from the lower surface between the edge portion and the end portion. With this configuration, the strength of the first frame portion formed by die casting is improved and the weight is reduced.

[0065] (5) The vehicle battery case according to (2), wherein the housing has an internal side member that extends in the longitudinal direction of the vehicle so as to span between the pair of first frame sections, and the ends of the internal side member are connected to the front and rear ends of the end housing section which is located on the central side of the first frame section in the vehicle width direction and is formed in a rectangular shape. With this configuration, the die-cast first frame section can be efficiently reinforced by connecting the ends of the internal side member to the end housing section.

[0066] (6) The vehicle battery case according to (5), wherein the housing further has an internal cross member that extends in the vehicle width direction so as to span between the pair of second frame portions, and the internal side member has one end in the front-rear direction connected to the front or rear end of the end housing portion and the other end in the front-rear direction connected to the internal cross member. With this configuration, collision energy transmitted to the internal side member via the first frame portion can be dispersed outward in the vehicle width direction by the internal cross member.

[0067] (7) The vehicle battery case according to (5) or (6), wherein the internal cross member is arranged adjacent to the end housing. With this configuration, since the internal cross member is provided along the vehicle width direction of the first frame, the first frame can be efficiently reinforced.

[0068] (8) The vehicle battery case according to any one of (5) to (7), wherein the first frame portion has a bracket for fixing to the vehicle frame, and the bracket overlaps with the internal side member in the vehicle width direction. With this configuration, collision energy input to the vehicle is smoothly transmitted from the bracket through the first frame portion to the internal side member. Therefore, the die-cast first frame portion can be efficiently protected.

[0069] 1 Vehicle structure 1A Front of vehicle structure 1B Rear of vehicle structure 3 Dash panel 3b Front 5 Floor pan 5a Underside of floor pan 7 Backbone 7a Underside of backbone 8 Front pillar 9 Side sill 11 Dash cross member 12 Backbone cross member 12a Projection 12b Base 13 Front side member 13a Front-rear extension 13b Inclined part 14 Front stringer 31 First rear cross member 32 Second rear cross member (cross member) 32a Cross center part 32b Cross end 33 Rear side member (side member) 33a Front-rear extension 33b Inclined part (side member) 32c Ridge 34 Rear stringer 35 Third rear cross member 36 Fourth rear cross member 41 Front center bracket 43 Front end bracket 45 Rear center bracket 47 Rear end bracket (fixing part) 49 Bolt 50 Battery case 51 Front part of first frame 51a Front end 51b Bent part 52 Rear part of first frame (first frame part) 52a Rear end 52b Inclined part 53 Second frame part 54 Internal side member 54a First internal side member 54b Second internal side member 55 Internal cross member 55a First internal cross member 55b Second internal cross member 55c Third internal cross member 55d Fourth internal cross member 56 Bottom plate 57 Cover body 57A First cover body 57B Second cover body 58 Rib 61 Front end housing part (end housing part) 62 Rear end housing part (end housing part) 63 Housing part 64 Second housing part

Claims

1. A vehicle battery case having a housing for housing battery cells, wherein the lower part of the vehicle battery case comprises a pair of first frame portions extending in the vehicle width direction and constituting both ends in the vehicle front-rear direction, and a pair of second frame portions which are skeletal members extending in the vehicle front-rear direction, wherein only the pair of first frame portions are formed by die-casting.

2. The vehicle battery case according to claim 1, wherein the first frame portion has an end housing portion formed adjacent to the housing portion formed between the pair of second frame portions.

3. The vehicle battery case according to claim 2, wherein the first frame portion has edges that extend in the vehicle width direction and form a front end and a rear end, and the edges have bent portions at both ends in the vehicle width direction that bend toward the longitudinal direction of the vehicle.

4. The vehicle battery case according to claim 3, wherein the first frame portion has a plurality of ribs extending vertically from the lower surface between the edge portion and the end housing portion.

5. The vehicle battery case according to claim 2, wherein the housing has an internal side member that extends in the longitudinal direction of the vehicle so as to span between the pair of first frame portions, and the ends of the internal side member are connected to the front and rear ends of the end housing portion which is arranged on the central side of the first frame portion in the vehicle width direction and is formed in a rectangular shape.

6. The vehicle battery case according to claim 5, wherein the housing further has an internal cross member extending in the vehicle width direction so as to span between the pair of second frame portions, and the internal side member has one end in the front-rear direction connected to the front or rear end of the end housing and the other end in the front-rear direction connected to the internal cross member.

7. The vehicle battery case according to claim 6, wherein the internal cross member is arranged adjacent to the end housing portion.

8. The vehicle battery case according to claim 5, wherein the first frame portion has a bracket for fixing to the vehicle frame, and the bracket overlaps with the internal side member in the vehicle width direction.

Images