Vehicle underbody structure

Abstract

A vehicle lower structure that suppresses a decrease in impact absorption performance with respect to a load is provided. The vehicle lower structure includes: a pair of side frames extending in a vehicle front-rear direction; a battery pack disposed between the side frames; a cross member erected between the side frames at a vehicle lower side of the battery pack; an energy absorbing member disposed at a vehicle width direction outer side of the battery pack and a vehicle lower side of the side frame, a vehicle width direction outer end portion of the cross member is curved outward in the vehicle front-rear direction from a point at which the vehicle width direction outer end portion reaches the energy absorbing member and is mounted to the side frame when viewed from above, and a vehicle front-rear direction outer end portion of the energy absorbing member is disposed along a face of the vehicle width direction outer end portion of the cross member that faces inward in the vehicle front-rear direction, and a reinforcing member is provided on the curved portion of the cross member, the reinforcing member having a plane that opposes the energy absorbing member in the vehicle width direction.

Description

Technical Field

[0001] This disclosure relates to a vehicle substructure. Background Technology

[0002] Previously, it was known that there were electric vehicle body structures in which multiple transverse members extending in the vehicle width direction were mounted between a pair of left and right frames extending in the front-rear direction, and a battery pack was arranged on the upper side of the multiple transverse members (for example, see Japanese Patent Application Publication No. 2018-144700).

[0003] Furthermore, in frame vehicles, a transverse member is installed between a pair of left and right side frames to suppress torsion. However, when the energy absorption component is positioned on the outer side of the battery pack in the vehicle width direction and on the lower side of the side frame, in order to accommodate the outer end of the transverse member in the vehicle width direction, a portion of the energy absorption component needs to be cut into a roughly rectangular shape when viewed from below.

[0004] Therefore, in the event of a side collision, when a load is input to the energy-absorbing component from the outside of the vehicle width direction, a tensile stress relative to the outside of the vehicle width direction will act on the portion of the energy-absorbing component that houses the transverse member at the outside of the vehicle width direction, through the outer end of the transverse member. This could cause the energy-absorbing component to fracture. In other words, it may not be able to fully utilize its impact absorption performance against loads input from the outside of the vehicle width direction. Summary of the Invention

[0005] This disclosure provides a vehicle substructure capable of suppressing a decrease in impact absorption performance against loads input from the outside of the vehicle width direction.

[0006] The first embodiment of the vehicle lower structure disclosed herein includes: a pair of left and right side frames extending in the vehicle longitudinal direction; a battery pack disposed between the side frames; a transverse member mounted between the side frames at the vehicle underside of the battery pack; and an energy absorption member disposed at the vehicle width direction outer side of the battery pack and at the vehicle underside of the side frames. When viewed from below, the vehicle width direction outer end of the transverse member bends outward in the vehicle longitudinal direction starting from a point reaching the energy absorption member and is mounted on the side frame. Furthermore, the vehicle longitudinal direction outer end of the energy absorption member is disposed along a surface of the vehicle width direction outer end of the transverse member facing inward in the vehicle longitudinal direction. A reinforcing member is provided at the bent portion of the transverse member, the reinforcing member having a plane opposite to the energy absorption member in the vehicle width direction.

[0007] According to the vehicle lower structure of the first embodiment, a battery pack is disposed between a pair of left and right side frames extending in the vehicle's longitudinal direction. Furthermore, a transverse member is erected between the side frames on the vehicle's lower side of the battery pack, and an energy absorption component is disposed on the outer side of the battery pack in the vehicle's width direction and on the vehicle's lower side of the side frames.

[0008] Here, when viewed from below, the outer end of the transverse member in the vehicle width direction bends outward in the vehicle longitudinal direction, starting from the point where it reaches the energy-absorbing component, and is mounted on the side frame. The outer end of the energy-absorbing component in the vehicle longitudinal direction is positioned along the surface of the outer end of the transverse member in the vehicle width direction facing inward in the vehicle longitudinal direction. Furthermore, a reinforcing member with a plane opposite to the energy-absorbing component in the vehicle width direction is provided at the bent portion of the transverse member.

[0009] Therefore, in side collisions, even if the load is input to the energy-absorbing component from the outside of the vehicle width direction, it is difficult for tensile stress to act relatively outward in the vehicle width direction at the outer end of the transverse member and the outer end of the energy-absorbing component in the vehicle front-rear direction, thus making it difficult for the energy-absorbing component to break. Consequently, the load input from the outside of the vehicle width direction is effectively absorbed by the energy-absorbing component and effectively blocked by the reinforcing member. In other words, it is possible to suppress the reduction in impact absorption performance against loads input from the outside of the vehicle width direction.

[0010] Furthermore, the second type of vehicle substructure disclosed herein includes: a body frame having a pair of left and right side frames extending in the vehicle longitudinal direction, a front frame connecting the front vehicle side portions of the side frames in the vehicle width direction, and a rear frame connecting the rear vehicle side portions of the side frames in the vehicle width direction; a battery pack disposed inside the body frame; a subframe having transverse members mounted between the side frames on the vehicle underside of the battery pack and supporting the battery pack from the vehicle underside; and an energy absorption component disposed within the body frame. When viewed from below, at the outer end of the battery pack in the vehicle width direction and at the lower side of the side frame, the outer end of the transverse member in the vehicle width direction bends outward in the vehicle longitudinal direction starting from the point where it reaches the energy absorption component and is mounted on the side frame. Furthermore, the outer end of the energy absorption component in the vehicle longitudinal direction is arranged along the surface of the outer end of the transverse member in the vehicle width direction facing inward in the vehicle longitudinal direction. A reinforcing member is provided at the bent portion of the transverse member, and the reinforcing member has a plane opposite to the energy absorption component in the vehicle width direction.

[0011] According to the second embodiment of the vehicle substructure, the front portion of a pair of side frames extending in the vehicle's longitudinal direction is connected in the vehicle width direction via a front frame, and the rear portion of the side frames is connected in the vehicle width direction via a rear frame, thus forming a body frame. Furthermore, a battery pack is disposed inside the body frame. Additionally, a subframe supporting the battery pack from the vehicle's lower side has a transverse member mounted between the side frames at the vehicle's lower side of the battery pack, and an energy absorption component is disposed at the vehicle's lower side of the side frames and outside the vehicle width direction of the battery pack.

[0012] Here, when viewed from below, the outer end of the transverse member in the vehicle width direction bends outward in the vehicle longitudinal direction, starting from the point where it reaches the energy-absorbing component, and is mounted on the side frame. The outer end of the energy-absorbing component in the vehicle longitudinal direction is positioned along the surface of the outer end of the transverse member in the vehicle width direction that faces inward in the vehicle longitudinal direction. Furthermore, a reinforcing member with a plane opposite to the energy-absorbing component in the vehicle width direction is provided at the bent portion of the transverse member.

[0013] Therefore, in side collisions, even if the load is input to the energy-absorbing component from the outside of the vehicle width direction, it is difficult for a tensile stress relative to the outside of the vehicle width direction to act on the outer end of the energy-absorbing component in the vehicle front-rear direction through the outer end of the transverse member. This makes it difficult for the energy-absorbing component to break. Thus, the load input from the outside of the vehicle width direction is effectively absorbed by the energy-absorbing component and effectively blocked by the reinforcing member. In other words, it is possible to suppress the reduction in impact absorption performance against loads input from the outside of the vehicle width direction.

[0014] Furthermore, the third-party vehicle lower structure disclosed herein is a vehicle lower structure of the first or second type, wherein the reinforcing member is formed as a bottom-view triangular shape having an inclined wall between the face of the transverse member facing the inward direction of the vehicle's front and rear directions and the face of the energy-absorbing member facing the inward direction of the vehicle's width.

[0015] According to the third-party vehicle substructure, the reinforcing member is formed as a bottom-view triangular shape with an inclined wall between the inner surface of the transverse member facing the vehicle's longitudinal direction and the inner surface of the energy-absorbing member facing the vehicle's width direction. Therefore, the rigidity of the reinforcing member is increased, and loads input from the outer side in the vehicle's width direction are effectively blocked by the reinforcing member and the transverse member.

[0016] As described above, according to this disclosure, it is possible to suppress the reduction in impact absorption performance against loads input from the outside of the vehicle width direction. Attached Figure Description

[0017] Figure 1 This is a top view showing the outline of the vehicle body lower structure according to this embodiment.

[0018] Figure 2 This is a perspective view showing the lower body structure of the vehicle body involved in this embodiment.

[0019] Figure 3 This is an exploded perspective view showing the outline of the lower body structure of the vehicle body according to this embodiment.

[0020] Figure 4 for Figure 1 The XX line in the outline view of the rear view.

[0021] Figure 5 This is a top view showing an enlarged portion of the lower body structure of the vehicle body according to this embodiment.

[0022] Figure 6 This is a top view showing the state when a load is input into the vehicle body substructure according to this embodiment. Detailed Implementation

[0023] The embodiments disclosed herein will now be described in detail based on the accompanying drawings. For ease of explanation, arrows marked UP will be used to indicate the upward direction of the vehicle, FR to indicate the forward direction of the vehicle, and RH to indicate the rightward direction of the vehicle. Furthermore, in the following description, unless otherwise specified, the directions of up / down, front / back, and left / right refer to the directions within the vehicle. The left / right direction is synonymous with the width direction of the vehicle.

[0024] like Figure 1 As shown, the frame vehicle 12, which is a vehicle equipped with the vehicle substructure 10 according to this embodiment, is mainly an electric vehicle (BEV) or a fuel cell vehicle (FCEV). The frame vehicle 12 has a pair of side frames 14 arranged on the outer side in the vehicle width direction and extending in the front-rear direction. Each side frame 14 is formed to have a rectangular closed cross-section when viewed in cross-section from the front-rear direction. In addition, a front wheel 22 and a rear wheel 24 are respectively arranged on the outer side in the vehicle width direction on the front side and the rear side of each side frame 14.

[0025] In addition, such as Figure 2 , Figure 3 As shown, the front and rear sides of each side frame 14 have suspension units arranged on the lower side (see reference). Figure 1 Therefore, when viewed from the side in the width direction of the vehicle, the side frame 14 is located above the central side of each side frame 14. In other words, the front and rear sides of each side frame 14 have inclined portions that slope forward and backward from the central side, respectively, and extend forward and backward from each inclined portion.

[0026] Furthermore, a front connecting frame 16 (front frame) extending along the vehicle width direction is provided at the front part (front side portion) of each side frame 14, and a rear connecting frame 18 (rear frame) extending along the vehicle width direction is provided at the rear part (rear side portion) of each side frame 14. That is, the front ends of the side frames 14 are connected in the vehicle width direction via the front connecting frame 16, and the rear ends of the side frames 14 are connected in the vehicle width direction via the rear connecting frame 18. Thus, a vehicle body frame 20 that appears to be roughly rectangular when viewed from above is formed.

[0027] In addition, such as Figure 2 , Figure 3 As shown, a battery pack 26 is disposed on the inner side of the vehicle frame 20 (between the side frames 14). The battery pack 26 has a generally rectangular box-shaped housing 26A that houses multiple battery cells (not shown), and is supported from below by a sub-frame 30 disposed on the inner side of the vehicle frame 20. That is, the sub-frame 30 is disposed on the lower side of the battery pack 26.

[0028] The subframe 30 is formed, for example, from high-strength steel, and has a first frame 32 with a rectangular closed cross-section extending in the longitudinal direction at the center of the vehicle width direction of the body frame 20, and a second frame 34 with a rectangular closed cross-section extending in the vehicle width direction at approximately the center of the longitudinal direction of the body frame 20.

[0029] That is, the subframe 30 is configured to be roughly “+” shaped when viewed from above using the first frame 32 and the second frame 34, and the central part of the second frame 34 in the vehicle width direction is fitted into the rectangular cutout 32A formed on the roughly central part of the first frame 32 in the front-rear direction, and is integrally joined by welding or the like.

[0030] Furthermore, the outer ends of the second frame 34 in the vehicle width direction are structured such that they are formed into a generally elliptical shape when viewed from above, and are respectively joined and mounted on the lower surfaces of the side frames 14. In other words, the second frame 34 is mounted between a pair of side frames 14. Additionally, the first frame 32 is configured to have higher rigidity compared to the second frame 34. Specifically, the first frame 32 is formed, for example, with a thicker plate thickness compared to the second frame 34.

[0031] Furthermore, the subframe 30 has a third frame 36 extending in the vehicle width direction at the rear of the body frame 20, and the rear end of the first frame 32 is integrally joined to the central part of the third frame 36 in the vehicle width direction by welding or the like. In addition, when viewed from the rear, the third frame 36 is formed into a roughly "U" shape, which is bent upwards from both ends in the left and right directions.

[0032] Furthermore, the subframe 30 has multiple transverse members to suppress the torsion of the body frame 20 (in order to improve durability and strength performance). These transverse members are formed into a rectangular closed cross-section shape and extend in the vehicle width direction, and are mounted between a pair of side frames 14. That is, the subframe 30 has three transverse members 38, 40, and 42 at equal intervals in the front-rear direction on the front side of the second frame 34, and two transverse members 44 and 46 at equal intervals in the front-rear direction between the second frame 34 and the third frame 36.

[0033] On the first frame 32, which is located on the front side compared to the second frame 34, three rectangular cutouts 32A are formed at equal intervals in the front-rear direction. The central portions of each transverse member 38, 40, and 42 in the vehicle width direction are fitted into each cutout 32A in a fitting manner and integrally joined together by welding or the like. Furthermore, the outer ends of each transverse member 38, 40, and 42 in the vehicle width direction are respectively mounted on each side frame 14.

[0034] Similarly, on the first frame 32, which is located rearward compared to the second frame 34, two rectangular cutouts 32A are formed at equal intervals in the front-rear direction. The central portions of each transverse member 44, 46 in the vehicle width direction are fitted into each cutout 32A and integrally joined together by welding or the like. Furthermore, the outer ends of each transverse member 44, 46 in the vehicle width direction are respectively mounted on each side frame 14.

[0035] In addition, such as Figures 1 to 4As shown, energy absorption members 28, which are formed into a grid pattern when viewed in cross-sectional view from the front-rear direction, are arranged on the outer side of the battery pack 26 in the vehicle width direction and on the lower side of each side frame 14. A cutout 28C, which is roughly "U"-shaped when viewed from above, is formed on the inner side of the energy absorption member 28 in the vehicle width direction at approximately the center in the front-rear direction, and is capable of accommodating the outer end of the second frame 34 in the vehicle width direction.

[0036] In addition, such as Figure 1 As shown, the rear end (outer end in the longitudinal direction) 28B of the energy-absorbing component 28 extends to a position close to the rearmost lateral member 46, and the front end (outer end in the longitudinal direction) 28A of the energy-absorbing component 28 extends to a position no more than the second lateral member 40 from the front side. Here, the positional relationship between the outer end of the lateral member 40 in the vehicle width direction and the front end 28A of the energy-absorbing component 28 will be explained.

[0037] like Figure 1 , Figure 5 As shown, when viewed from below, the outer end of the transverse member 40 in the vehicle width direction bends forward (outer in the longitudinal direction) from the point where it reaches the energy-absorbing member 28 and is mounted on the lower surface of the side frame 14. Furthermore, when viewed from below, the inner portion of the front end 28A of the energy-absorbing member 28 in the vehicle width direction is positioned along the rear surface (facing the inner in the longitudinal direction) 40B of the outer end of the transverse member 40 in the vehicle width direction. In other words, when viewed from below, the inner portion of the front end 28A of the energy-absorbing member 28 is cut into the shape of the rear surface 40B of the outer end of the transverse member 40 in the vehicle width direction.

[0038] Furthermore, a reinforcing plate 48, serving as a reinforcing member, is provided on the bent portion 40A of the transverse member 40 (hereinafter referred to as the "bent portion"). The reinforcing plate 48 has a plane 48A facing the energy absorption member 28 in the vehicle width direction. The reinforcing plate 48 is formed to be approximately triangular in shape when viewed from below, and its front portion is integrally joined to the lower surface and rear surface of the bent portion 40A of the transverse member 40 by welding or the like.

[0039] Thus, the structure is such that the outer end of the reinforcing plate 48 in the vehicle width direction is set as a plane 48A and faces the energy absorption member 28 in a manner close to or in contact with it. Furthermore, the rear part of the reinforcing plate 48 is set as an inclined wall 48B located between the rear surface (facing the inner side in the vehicle width direction) of the curved portion 40A of the transverse member 40 and the inner surface (facing the inner side in the vehicle width direction) of the energy absorption member 28 when viewed from below.

[0040] The function of the vehicle lower structure 10, which is configured as described above in this embodiment, will now be explained.

[0041] As described above, the front portions of a pair of left and right side frames 14 extending in the longitudinal direction are connected in the vehicle width direction via a front connecting frame 16, and the rear portions of the side frames 14 are connected in the vehicle width direction via a rear connecting frame 18, thereby forming a body frame 20. Furthermore, a battery pack 26 is disposed on the inner side of the body frame 20 (between the side frames 14). That is, the battery pack 26 is supported from the lower side via a sub-frame 30.

[0042] Here, at the center of the vehicle body frame 20 in the vehicle width direction below the battery pack 26, the first frame 32 of the sub-frame 30, which is configured to be highly rigid, extends in the longitudinal direction, and at approximately the center of the vehicle body frame 20 in the longitudinal direction, the second frame 34 of the sub-frame 30 is mounted on the side frame 14. Therefore, the battery pack 26, which is a heavy object, can be stably supported.

[0043] In addition, such as Figure 4 As shown, since the subframe 30 is located below the body frame 20 (side frame 14) when viewed from the side, the battery pack 26 is surrounded by the body frame 20. More specifically, when viewed from the side, at least a portion of the battery pack 26 in the height direction overlaps with the body frame 20, and at least a portion of the battery pack 26 in the height direction is surrounded by the body frame 20.

[0044] Therefore, it can improve the mounting stability of the battery pack 26 and enhance the protection performance of the battery pack 26 in the event of a collision with the frame vehicle 12. That is, even if a collision load is input to the frame vehicle 12 from the front-rear direction or the vehicle width direction, the battery pack 26 can be effectively protected from the impact of the collision load.

[0045] Furthermore, an energy-absorbing component 28 is disposed on the outer side of the battery pack 26 in the vehicle width direction and on the lower side of the side frame 14, and the sub-frame 30 has a transverse member 40 extending in the vehicle width direction. When viewed from below, the outer end of the transverse member 40 in the vehicle width direction bends forward from the point where it reaches the energy-absorbing component 28 and is mounted on the side frame 14. The front end portion 28A of the energy-absorbing component 28 is disposed along the rear surface 40B of the outer end portion of the transverse member 40 in the vehicle width direction. Moreover, a reinforcing plate 48 having a plane 48A opposite the energy-absorbing component 28 in the vehicle width direction is provided on the curved portion 40A of the transverse member 40.

[0046] Therefore, in the event of a side collision with the frame vehicle 12, even if the load is input to the energy-absorbing component 28 from the outside of the vehicle width direction, it is difficult for tensile stress relative to the outside of the vehicle width direction to act on the front end 28A of the energy-absorbing component 28 through the outer end of the transverse member 40, thus making it difficult for the energy-absorbing component 28 to break. Furthermore, the inner portion of the front end 28A of the energy-absorbing component 28 in the vehicle width direction is effectively supported from the inside of the vehicle width direction by the plane 48A of the reinforcing plate 48.

[0047] Therefore, as Figure 6 As shown, loads input from the outside of the vehicle width direction due to obstacles such as W are effectively absorbed by the energy-absorbing member 28 and effectively blocked by the plane 48A of the reinforcing plate 48 (the energy-absorbing member 28 supported by the plane 48A). Therefore, in the event of a side collision of the frame vehicle 12, the reduction in impact absorption performance against loads input from the outside of the vehicle width direction can be suppressed.

[0048] Furthermore, the reinforcing plate 48 is formed such that, when viewed from below, it has an inclined wall 48B located between the rear surface of the transverse member 40 and the inner surface of the energy-absorbing member 28. Therefore, compared to a reinforcing plate that is not formed into a roughly triangular shape when viewed from below (illustration omitted), the rigidity of the reinforcing plate 48 can be improved, thereby effectively blocking loads input from the outside in the vehicle width direction through the reinforcing plate 48 and the transverse member 40.

[0049] More specifically, since the load input from the outside of the vehicle width direction to the plane 48A of the reinforcing plate 48 can be efficiently transferred to the transverse member 40 via the front and rear (inclined wall 48B) of the reinforcing plate 48, it can be effectively blocked by the transverse member 40 and then by the side frame 14 (body frame 20).

[0050] While the vehicle substructure 10 according to this embodiment has been described above based on the accompanying drawings, the vehicle substructure 10 according to this embodiment is not limited to the structure shown in the drawings, but can be appropriately modified within the scope of the present disclosure. For example, the vehicle according to this embodiment is not limited to the frame vehicle 12. Furthermore, the transverse members 38, 40, 42, 44, and 46 are not limited to being formed in a rectangular closed cross-sectional shape, but can also be formed in a generally "U" shaped cross-section.

[0051] Furthermore, although the transverse member 40 located at the front end 28A of the energy absorption member 28 has been described in the above embodiment, the transverse member 46 located at (near) the rear end 28B of the energy absorption member 28 may also be constructed in the same way. In addition, the reinforcing plate 48 is only required to be shaped to effectively block loads input from the outside in the vehicle width direction, and is not limited to being formed into a roughly triangular shape when viewed from below.

Claims

1. A vehicle substructure, comprising: A pair of left and right side frames, which extend in the front-rear direction of the vehicle; A battery pack, which is configured between the side frames; A transverse member is mounted between the side frames on the vehicle-side underside of the battery pack; An energy absorption component is disposed on the outer side of the battery pack in the vehicle width direction and on the lower side of the side frame in the vehicle direction. When viewed from below, the outer end of the transverse member in the vehicle width direction bends outward in the vehicle longitudinal direction, starting from the point where it reaches the energy-absorbing component, and is mounted on the side frame. Furthermore, the outer end of the energy-absorbing component in the vehicle longitudinal direction is arranged along the surface of the outer end of the transverse member in the vehicle width direction facing inward in the vehicle longitudinal direction. A reinforcing member is provided at the bent portion of the transverse member, the reinforcing member having a plane opposite the energy-absorbing member in the vehicle width direction.

2. A vehicle substructure, comprising: A vehicle body frame having a pair of left and right side frames extending in the vehicle longitudinal direction, a front frame connecting the front vehicle side portions of the side frames in the vehicle width direction, and a rear frame connecting the rear vehicle side portions of the side frames in the vehicle width direction. The battery pack is located inside the vehicle body frame; A subframe having transverse members mounted between the side frames on the vehicle underside of the battery pack, and supporting the battery pack from the vehicle underside. An energy absorption component is disposed on the outer side of the battery pack in the vehicle width direction and on the lower side of the side frame in the vehicle direction. When viewed from below, the outer end of the transverse member in the vehicle width direction bends outward in the vehicle longitudinal direction, starting from the point where it reaches the energy-absorbing component, and is mounted on the side frame. Furthermore, the outer end of the energy-absorbing component in the vehicle longitudinal direction is positioned along the surface of the outer end of the transverse member in the vehicle width direction that faces inward in the vehicle longitudinal direction. A reinforcing member is provided at the bent portion of the transverse member, the reinforcing member having a plane opposite the energy-absorbing member in the vehicle width direction.

3. The vehicle substructure as described in claim 1 or 2, wherein, The reinforcing member is formed as a bottom-view triangular shape having an inclined wall between the inner side of the transverse member facing the vehicle's front-rear direction and the inner side of the energy-absorbing member facing the vehicle's width direction.

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