Vehicle structure

Abstract

This vehicle structure includes: a pair of side members extending in a vehicle longitudinal direction; a cross member extending in a vehicle width direction so as to bridge between the pair of side members; a first frame part that forms a lower part of a battery case fixed to each of the pair of side members and extends in the vehicle width direction; and a fixing part that fixes the first frame part to the side members. The cross member, the first frame part, and the fixing part are arranged at substantially the same position in the vehicle longitudinal direction. The cross member protrudes to a side opposite to the first frame part in a vertical direction.

Description

Vehicle structure

[0001] The present invention relates to a vehicle structure.

[0002] Patent Document 1 discloses a vehicle body for an electric vehicle in which the structure of the rear portion of the vehicle body is improved for the purpose of preventing impact energy from being transmitted to a high-voltage battery. The vehicle body of Patent Document 1 comprises: side sills (reference numeral 100) coupled to both side surfaces of a floor panel in the front-rear direction; rear side members (reference numeral 200) each having a front end overlapping with a rear end of the corresponding side sill and extending rearward along the side surface of the floor panel to be coupled thereto; a battery (reference numeral 700) located below the floor panel and mounted to a side sill portion forward of the rear side members and an overlapping portion of the side sill and the rear side member; and a rear extension member (reference numeral 300) formed to have lower strength than the side sills and the rear side members, having a front end connected to a rear end of the corresponding rear side member and extending rearward along the side surface of the floor panel to be coupled thereto.

[0003] Accordingly, when a collision occurs at the rear portion of a vehicle, since the strength of the rear extension member is lower than that of the rear side member and the side sill located forward thereof, the rear extension member is compressed and deformed in the rear first energy-absorbing section, and is intended to primarily absorb collision energy while being crushed. Further, the front second energy-absorbing section is provided with the rear side member formed of a member having higher strength than the rear extension member, whereby the rear side member is bent and deformed, and is intended to further absorb collision energy that could not be absorbed in the first energy-absorbing section.

[0004] Japanese Unexamined Patent Publication No. 2021-181300

[0005] The invention described in Patent Document 1 involves connecting a first cross member (reference numeral 400) extending in the vehicle width direction between rear side members (reference numeral 200), and providing a battery mount (reference numeral M1) in the middle of the first cross member (reference numeral 400) on which the battery (reference numeral 700) is mounted, with the aim of suppressing the transmission of collision energy to the battery (reference numeral 700). However, in some cases the rigidity of the vehicle body is not yet sufficient, and there is a possibility that the collision energy transmitted to the first cross member (reference numeral 400) may cause damage to the battery mount (reference numeral M1) or the battery (reference numeral 700).

[0006] Therefore, the present invention aims to provide a vehicle structure that efficiently strengthens the rigidity of the vehicle body, improves handling stability, and efficiently protects the battery in the battery case when an impact is applied from the front, rear, or side of the vehicle.

[0007] The present invention comprises the following configuration: a pair of side members extending in the longitudinal direction of the vehicle; a cross member extending in the vehicle width direction so as to bridge between the pair of side members; a first frame portion extending in the vehicle width direction and forming the lower part of a battery case fixed to each of the pair of side members; and a fixing portion for fixing the first frame portion to the side members, wherein the cross member, the first frame portion and the fixing portion are arranged at substantially the same position in the longitudinal direction of the vehicle, and the cross member protrudes in the vertical direction on the side opposite to the first frame portion.

[0008] According to the present invention, a ring-shaped structure is formed by the battery case, the cross member, and the fixing part that secures the battery case to the side member, thereby improving the rigidity of the vehicle body. This improves handling stability and efficiently protects the battery inside the battery case when an impact is applied from the front, rear, or side of the vehicle.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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).

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] (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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] (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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] (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).

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] The pair of first inner side members 54a are arranged spaced apart from each other in the vehicle width direction, each connected to the front end portion of the front end housing portion 61 and extending in the front-rear direction. The rear end portions of the pair of first inner side members 54a are connected to a first inner cross member 55a described later.

[0042] The second inner side member 54b extends in the front-rear direction so as to connect the rear end portion of the rear end housing portion 62 and the first inner cross member 55a described later. The position of the second inner side member 54b in the vehicle width direction is not particularly limited, but in the illustrated example, it is arranged at the center portion of the battery case 50 in the vehicle width direction.

[0043] According to this arrangement, when the vehicle has a front collision or a rear collision, the load input to the inner side members 54 is once dispersed to both sides in the vehicle width direction by the first inner cross member 55a described later, so that the load dispersion effect is enhanced. In addition, since 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, it is possible to improve steering stability. Further, considering that batteries (not shown) are accommodated in a plurality of regions divided by the second inner side member 54b and the first to fourth inner cross members 55a to 55d described later, arranging the second inner side member 54b at the center portion in the vehicle width direction is preferable from the viewpoint of space efficiency.

[0044] The inner cross member 55 is a frame member that extends in the vehicle width direction inside the battery case 50 so as to bridge between the pair of second frame portions. The inner cross member 55 in the illustrated example includes first to fourth inner cross members 55a to 55d arranged at predetermined intervals in the front-rear direction. The first to fourth inner cross members 55a to 55d are arranged in this order from the front side. By providing such an inner cross member 55, the load input to the battery case 50 from the outside in the vehicle width direction can be transmitted in the vehicle width direction via the inner cross member 55. In addition, since the strong frame member that is the inner cross member 55 is provided, the battery case 50 can function as a part of the vehicle frame member.

[0045] The first inner cross member 55a connects the rear end portions of the pair of first inner side members 54a and the front end portion of the second inner side member 54b, and extends in the vehicle width direction so as to extend from the left end portion to the right end portion of the battery case 50. Accordingly, a 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 can be transmitted to the rear end portion of the battery case 50.

[0046] A 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.

[0047] The first inner cross member 55a is arranged adjacent to a rear end of a first frame front portion 51 (front end housing portion 61), and the fourth inner cross member 55d is arranged adjacent to a front end of a first frame rear portion 52 (rear end housing 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.

[0048] As shown in Figs. 7 to 9, the bottom plate 56 is a plate-like 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 constitutes a bottom surface of a housing portion 63 that is defined by the inner side members 54 and the inner cross members 55 and houses 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 a rib 58 formed on the lower surface of the first frame rear portion 52.

[0049] As shown in Figure 7, the cover body 57 is a component that constitutes the upper surface of the battery case 50. The cover body 57 has a first cover body 57A that covers the upper surfaces of the housing sections 61, 62, and 63 and also serves as the bottom plate of the second housing section 64 formed above the housing sections 61, 62, and 63, and a second cover body 57B that covers the upper part of the housing, such as a battery, placed on the upper surface of the first cover body 57A. With this configuration, the battery case 50 can be mounted in a space-efficient manner by stacking batteries vertically. At this time, the upper surface of the battery case 50 (second cover body 57B) is formed along the second rear cross member 32 which is curved in a convex shape toward upward.

[0050] The battery case 50 described above has a complex external shape and housing sections 61 and 62 at its front and rear ends, which are formed by die-casting a first frame front section 51 and a first frame rear section 52. The intermediate section in the front-rear direction that constitutes the housing section 63 in which the battery cells are housed is composed of a second frame section 53 made of a frame-like skeletal member, an internal side member 54, and an internal cross member 55. This makes it possible to extend the front and rear ends of the battery case 50 as much as possible according to the vehicle structure to secure space for mounting high-voltage equipment related to the battery, while also increasing the rigidity of the housing space in which the battery cells are housed. Furthermore, by limiting the die-cast frame portion of the battery case 50 to only the front and rear ends and by forming multiple ribs 58, the increase in weight can be kept to a minimum.

[0051] (Mounting structure of battery case 50) Next, the mounting structure of the battery case 50 will be described based on Figures 3 and 7, etc. The battery case 50 has a second frame portion 53 that extends in the front-rear direction and overlaps with a pair of side sills 9, a first frame front portion 51 that overlaps with a backbone cross member 12, and a first frame rear portion 52 that overlaps with a second rear cross member 32 and a pair of rear stringers 34, which will be described later.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] As described above, the following matters are disclosed in this specification: (1) A vehicle structure comprising: a pair of side members extending in the longitudinal direction of the vehicle; a cross member extending in the vehicle width direction so as to span between the pair of side members; a first frame portion extending in the vehicle width direction and forming the lower part of a battery case fixed to each of the pair of side members; and a fixing portion for fixing the first frame portion to the side members, wherein the cross member, the first frame portion and the fixing portion are arranged at substantially the same position in the longitudinal direction of the vehicle, and the cross member protrudes in the vertical direction on the opposite side from the first frame portion. With this configuration, an annular structure is formed by the first frame portion that constitutes the lower part of the battery case, the cross member and the fixing portion that fixes the first frame portion to the side member, so that the rigidity of the vehicle body is further improved. As a result, the battery in the battery case can be efficiently protected when an impact is applied from the front, rear or side of the vehicle.

[0063] (2) The vehicle structure according to (1), wherein the cross member has a C-shaped cross section. With this configuration, the rigidity of the cross member against external forces acting toward the battery case is improved.

[0064] (3) The vehicle structure according to (1) or (2), wherein the cross member extends along the upper surface of the battery case. With this configuration, the rigidity of the cross member and the upper surface of the battery case is improved.

[0065] (4) The vehicle structure according to any one of (1) to (3), wherein the cross member has a pair of ridges extending in the longitudinal direction of the vehicle. With this configuration, the rigidity of the cross member is improved, and the effect of improving rigidity by the annular structure combined with the battery case is also improved.

[0066] (5) The lower part of the battery case comprises a pair of first frame portions extending in the vehicle width direction and constituting both ends in the vehicle longitudinal direction, and a pair of second frame portions which are skeletal members extending in the vehicle longitudinal direction, wherein only the pair of first frame portions are formed by die casting, and this configuration makes it possible to efficiently increase the storage space in the lower part of the vehicle and to improve the rigidity of the battery case at the same time.

[0067] (6) The vehicle structure according to (5), wherein the first frame portion has an end housing portion adjacent to a housing portion formed between the pair of second frame portions. With this configuration, since the first frame portion is formed by die casting, complex shapes including the end housing portion can be mass-produced at low cost.

[0068] (7) The vehicle structure according to (6), 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. With this configuration, the rigidity of the first frame portion is improved.

[0069] (8) The vehicle structure according to (7), 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. With this configuration, the weight of the first frame portion formed by die casting is reduced.

[0070] 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 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 structure comprising: a pair of side members extending in the longitudinal direction of the vehicle; a cross member extending in the vehicle width direction so as to bridge between the pair of side members; a first frame portion extending in the vehicle width direction and forming the lower part of a battery case fixed to each of the pair of side members; and a fixing portion for fixing the first frame portion to the side members, wherein the cross member, the first frame portion and the fixing portion are arranged at substantially the same position in the longitudinal direction of the vehicle, and the cross member protrudes in the vertical direction on the side opposite to the first frame portion.

2. The vehicle structure according to claim 1, wherein the cross member has a C-shaped cross section.

3. The vehicle structure according to claim 1, wherein the cross member extends along the upper surface of the battery case.

4. The vehicle structure according to claim 1, wherein the cross member has a pair of ridges extending in the longitudinal direction of the vehicle.

5. The vehicle structure according to claim 1, wherein the lower part of the battery case has a pair of first frame portions that extend in the vehicle width direction and constitute both ends in the vehicle longitudinal direction, and a pair of second frame portions that are skeletal members extending in the vehicle longitudinal direction, and of the first frame portions and the second frame portions, only the pair of first frame portions are formed by die casting.

6. The vehicle structure according to claim 5, wherein the first frame portion has an end housing portion formed adjacent to a housing portion formed between the pair of second frame portions.

7. The vehicle structure according to claim 6, 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.

8. The vehicle structure according to claim 7, 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.

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