Vehicle bottom structure

Abstract

To reduce upward deflection of a share panel when an object collides with the share panel from a vehicle lower side.SOLUTION: A vehicle bottom structure includes a battery pack 16, and a plurality of outer cross members 18 attached to a bottom plate 36 of the battery pack 16 and arranged at intervals in a vehicle longitudinal direction. An upper reinforcement member 61 having a dish-shaped cross section that opens downward is disposed on a lower surface of the lower wall 51 of each outer cross member 18. A share panel 20 having a projection part 22 in contact with a lower surface of each upper reinforcement member 61 is arranged below the plurality of upper reinforcement members 61. A lower reinforcement member 62 is disposed inside each protrusion 22 of the share panel 20. The lower reinforcement member 62, the share panel 20, the upper reinforcement member 61, and the lower wall 51 of the outer cross member 18 are overlapped and fastened by a bolt 80. Both end portions 75 of the lower surface of the upper reinforcement member 61 in the front-rear direction of the vehicle are located outside both end portions 55 of the lower wall 51 of the outer cross member 18 in the front-rear direction of the vehicle.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This specification discloses a bottom structure for an electric vehicle that mounts a battery pack below the floor. [Background technology]

[0002] Electric vehicles such as battery electric vehicles (BEVs) have been known for some time. Electric vehicles are equipped with a battery pack that supplies power to a traction motor. The battery pack is mounted below the floor of the vehicle compartment.

[0003] Patent Document 1 discloses a battery case that is mounted under the floor of the passenger compartment of an electric vehicle and that houses a battery inside. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-87250 Summary of the Invention [Problem to be solved by the invention]

[0005] The electric vehicle includes a battery pack mounted below the floor, a plurality of outer cross members arranged at intervals in the longitudinal direction of the vehicle below the battery pack, and a share panel arranged below the plurality of outer cross members to cover the battery pack from below. The share panel forms the bottom surface of the vehicle below the floor.

[0006] The battery pack has a case that houses the battery modules. Each of the outer cross members has a hat-shaped cross section that opens upward, extends in the vehicle width direction, and is attached to the outer surface of the bottom plate of the battery pack case. The lower wall (web) of each outer cross member overlaps a shear panel, and they are fastened together with bolts. In other words, the shear panels are held at intervals in the vehicle fore-and-aft direction by the outer cross members.

[0007] When an object collides with a shear panel from below the vehicle, the shear panel will bend upward between the two fastening points (fastening points to the two outer cross members) in the vehicle's fore-and-aft direction. This could bring the shear panel close to the battery pack, potentially damaging it. It is desirable to reduce the amount of upward bending of the shear panel when an object collides with it from below the vehicle.

[0008] This specification discloses a vehicle underbody structure that can reduce upward deflection of a shear panel when an object collides with the shear panel from below the vehicle. [Means for solving the problem]

[0009] The vehicle undercarriage structure disclosed herein includes a battery pack mounted below the floor and having a case that houses a battery module. The battery pack is located below the bottom plate of the case and includes a plurality of outer cross members spaced apart in the vehicle longitudinal direction. Each of the outer cross members has a hat-shaped cross section that opens upward, extends in the vehicle width direction, and is attached to the outer surface of the bottom plate of the case. An upper reinforcing member is disposed on the lower surface of the lower wall of each outer cross member, the upper reinforcing member having a dish-shaped cross section that opens downward and extending in the vehicle width direction. A shear panel is disposed below the upper reinforcing members, covering the bottom plate of the case. The shear panel is bent to contact the lower surface of each upper reinforcing member, thereby forming protrusions corresponding to the upper reinforcing members. A lower reinforcing member is disposed inside each of the protrusions of the shear panel, extending in the vehicle width direction. The lower reinforcing member, the shear panel, the upper reinforcing member, and the lower wall of the outer cross member are stacked and fastened together with bolts at intervals in the vehicle width direction. Both ends of the lower surface of the upper reinforcing member in the longitudinal direction of the vehicle are located outward from both ends of the lower wall of the outer cross member in the longitudinal direction of the vehicle.

[0010] According to the above configuration, when an object collides with the share panel from below the vehicle, compared to when the share panel is directly fastened to the lower wall of each outer cross member, the distance between the fulcrums of the bending moment of the share panel is shorter due to the upper reinforcing members whose both ends in the longitudinal direction of the vehicle are located outward from the outer cross members, thereby reducing the upward deflection of the share panel.

[0011] Furthermore, with the above-described configuration, the shear panel is sandwiched between the upper and lower reinforcing members, so when an object collides with the shear panel from below the vehicle, the shear panel is restricted from moving toward the colliding object relative to the two reinforcing members (the upper and lower reinforcing members), thereby reducing upward deflection of the shear panel.

[0012] In the vehicle bottom structure of the present disclosure, the bolt may have its head located on the underside of the lower reinforcing member and fastened to a nut arranged on the upper surface of the lower wall of the outer cross member, and the underside of the lower reinforcing member may have a recess into which at least a portion of the head of the bolt extends inward.

[0013] This configuration can reduce the amount by which the bolt head protrudes from the underside of the vehicle, or can prevent the bolt head from protruding from the underside of the vehicle, which is expected to improve the aerodynamic performance of the vehicle. [Effects of the Invention]

[0014] According to the technology disclosed in this specification, it is possible to reduce upward deflection of a shear panel when an object collides with the shear panel from below the vehicle. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a perspective view schematically illustrating an upper surface of a share panel of the vehicle according to the embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3]FIG. 10 is a cross-sectional view showing the bolt areas of the upper / lower reinforcing members in another embodiment. [Figure 4] FIG. 10 is a cross-sectional view showing the non-bolt areas of the upper / lower reinforcing members in another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments will be described with reference to the drawings. In all drawings, equivalent elements are designated by the same reference numerals, and redundant explanations will be omitted. In the following description, unless otherwise specified, terms indicating directions and orientations, such as front, rear, left, right, up, down, etc., refer to directions and orientations relative to the vehicle. In each drawing, the arrow FR points forward, the arrow UP points upward, and the arrow RH points rightward.

[0017] Fig. 1 is a perspective view that schematically shows the top surface of a share panel 20 of a vehicle 12. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1, and also shows a battery pack 16 and a floor 14 that are located above the share panel 20. The vehicle 12 is an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or other electrically powered vehicle that is equipped with a battery pack 16 that supplies power to a motor (not shown) that serves as a power source.

[0018] As shown in Figure 2, the battery pack 16 is mounted below the floor 14 of the vehicle compartment. The vehicle 12 is equipped with a shared panel 20 that covers the battery pack 16 from below. The shared panel 20 forms the bottom surface of the vehicle below the floor 14.

[0019] The battery pack 16 includes a plurality of battery modules 30 and a case 32. The battery module 30 includes a battery stack formed by stacking a large number of battery cells. The case 32 is the outer shell of the battery pack 16. The case 32 houses a plurality of battery modules 30 inside. The case 32 is composed of a lower case and an upper case. The lower case has, for example, a bathtub shape, and the upper case has, for example, an inverted bathtub shape (a shape resembling an upside-down bathtub). The upper case is fixed on top of the lower case. Figure 2 shows a bottom plate 36 of the lower case and a top plate 34 of the upper case.

[0020] A plurality of inner cross members 40 are attached to the upper surface of the bottom plate 36 of the case 32. The inner cross members 40 are disposed in the gaps between adjacent battery modules 30 and extend in the vehicle width direction (vehicle left-right direction). The inner cross members 40 are folded plate members with a hat-shaped cross section that are composed of a web 41, a pair of flanges 42 erected on both side ends of the web 41, and a pair of arms 43 extending outward from the tips of the pair of flanges 42. The arms 43 of the inner cross members 40 are joined to the upper surface of the bottom plate 36.

[0021] The vehicle 12 is equipped with a plurality of outer cross members 18. The outer cross members 18 are located below the bottom plate 36 of the case 32 and are spaced apart in the vehicle longitudinal direction. Each outer cross member 18 has a hat-shaped cross section that opens upward and extends in the vehicle transverse direction. The outer cross member 18 is a folded plate member composed of a lower wall 51 (web), a pair of flanges 52 erected on both side ends of the lower wall 51, and a pair of arms 53 extending outward from the tips of the pair of flanges 52. The arms 53 of the outer cross member 18 are joined to the underside of the portion of the bottom plate 36 to which the arms 43 of the inner cross member 40 are joined. A weld nut 82 is welded to the inside of the outer cross member 18.

[0022] The vehicle 12 includes a plurality of upper reinforcing members 61. Each upper reinforcing member 61 is a long, narrow member that extends in the vehicle width direction and has a dish-shaped cross section (concave cross section) that opens downward. The upper reinforcing member 61 has a shape that expands from top to bottom in the vehicle front-rear direction (the short direction of the upper reinforcing member 61). The upper reinforcing member 61 may be made of, for example, a metal extrusion, steel, or resin material. The upper reinforcing member 61 is disposed on the lower surface of the lower wall 51 of each outer cross member 18. As shown in FIG. 1 , the upper reinforcing members 61 are disposed on the share panel 20 at intervals in the vehicle front-rear direction. Each upper reinforcing member 61 extends from the left end 28 to the right end 29 of the share panel 20. Note that each upper reinforcing member 61 may be disposed only in the region that is inboard of each of the left end 28 and right end 29 of the share panel 20 in the vehicle width direction.

[0023] The shear panel 20 is the bottom plate of the vehicle and has a generally rectangular shape with the longitudinal direction of the vehicle in a plan view. The shear panel 20 may be made of, for example, aluminum or high-tensile steel (steel with high tensile strength). The shear panel 20 is located below the multiple upper reinforcing members 61 and covers the bottom plate 36 of the case 32 of the battery pack 16. The shear panel 20 is bent so as to contact the lower surface of each upper reinforcing member 61, thereby forming hollow convex portions 22 (protrusions) at positions corresponding to each upper reinforcing member 61. The convex portions 22 have a shape that widens in the longitudinal direction of the vehicle from top to bottom.

[0024] 1, the share panel 20 has a front end 26, a rear end 27, a left end 28, and a right end 29. Although not shown, the front end 26, the rear end 27, the left end 28, and the right end 29 are processed into desired shapes so that they can be attached to frame members of a vehicle. The front end 26, the rear end 27, the left end 28, and the right end 29 of the share panel 20 are attached to frame members of the front, rear, left, and right parts of the vehicle body, respectively.

[0025] The vehicle 12 includes a plurality of lower reinforcing members 62. Each lower reinforcing member 62 is a long, narrow member having a solid trapezoidal cross section and extending in the vehicle width direction. The lower reinforcing member 62 has a shape that expands from the top to the bottom in the vehicle front-rear direction (the short direction of the lower reinforcing member 62). The lower reinforcing member 62 may be made of, for example, a metal extrusion, a steel material, or a resin material. The lower reinforcing member 62 is disposed inside each of the protrusions 22 of the share panel 20. The lower surface of the lower reinforcing member 62 may be configured to be flush with the lower surface of the share panel 20 adjacent to the protrusion 22. As shown in FIG. 1 , each lower reinforcing member 62 extends from the left end 28 to the right end 29 of the share panel 20. The lower reinforcing member 62 may be disposed only in the region inward in the vehicle width direction of each of the left end 28 and the right end 29 of the share panel 20.

[0026] As shown in FIG. 1, the shear panel 20 has the protrusion 22 sandwiched between a lower reinforcing member 62 and an upper reinforcing member 61 at a distance in the vehicle longitudinal direction.

[0027] The upper reinforcing member 61 and the lower reinforcing member 62 (hereinafter referred to as the upper / lower reinforcing members 61, 62) are provided with a plurality of bolt through holes spaced apart in the vehicle width direction. FIG. 1 shows the bolt through hole 64 of the upper reinforcing member 61. A bolt 80 (see FIG. 2) inserted from below the lower reinforcing member 62 is passed through each bolt through hole of the upper / lower reinforcing members 61, 62. Hereinafter, the region in which the bolt through holes of the upper / lower reinforcing members 61, 62 are provided will be referred to as a bolt region 66 (see FIG. 1). Furthermore, the region between adjacent bolt through holes of the upper / lower reinforcing members 61, 62 will be referred to as a non-bolt region 67. The AA cross section of FIG. 2 shows the bolt regions 66 of two pairs of upper / lower reinforcing members 61, 62, and the non-bolt region 67 of one pair of upper / lower reinforcing members 61, 62 is shown in a speech bubble in the same figure.

[0028] 2, the lower reinforcing member 62, the protrusion 22 of the shear panel 20, the upper reinforcing member 61, and the lower wall 51 of the outer cross member 18 are stacked and fastened together with a bolt 80. The bolt 80 passes through a bolt through-hole in the lower reinforcing member 62 and penetrates the shear panel 20, passes through a bolt through-hole 64 in the upper reinforcing member 61 and penetrates the lower wall 51 of the outer cross member 18, and is fastened to a weld nut 82 of the outer cross member 18. Fastening points (bolt regions 66) using the bolts 80 and nuts 82 are provided side by side in the vehicle width direction on the upper and lower reinforcing members 61, 62 at intervals.

[0029] As shown in Figure 2, in each of the multiple upper reinforcing members 61, both vehicle fore-and-aft direction end portions 75 of the lower surface of the upper reinforcing member 61 are located outward from both vehicle fore-and-aft direction end portions 55 of the lower wall 51 of the outer cross member 18.

[0030] According to the embodiment described above, as shown in Fig. 2, when an object 110 on the road surface collides with the shear panel 20 and a collision load F is input to the shear panel 20, it is possible to reduce upward deflection of the shear panel 20. That is, when the shear panel 20 is directly fastened to the lower wall 51 of each outer cross member 18, the distance between the rear end 55 (reference symbol S1a in Fig. 2) of the front outer cross member 18 and the front end 55 (reference symbol S2a) of the rear outer cross member 18 becomes the fulcrum distance La of the bending moment of the shear panel 20 during an object collision.

[0031] On the one hand, according to the embodiments described above, an upper reinforcing member 61 is disposed between the shared panel 20 and the lower wall 51 of the outer cross member 18, and both ends 75 in the vehicle front-rear direction of the lower surface of the upper reinforcing member 61 are located outward of both ends 55 in the vehicle front-rear direction of the lower wall 51 of the outer cross member 18. Therefore, the distance between the rear end 75 (reference sign S1 in FIG. 2) of the front upper reinforcing member 61 and the front end 75 (reference sign S2) of the rear upper reinforcing member 61 becomes the fulcrum distance L of the bending moment of the shared panel 20 during an object collision. In this case, compared with the case where the shared panel 20 is directly fastened to the outer cross member 18, the fulcrum distance L of the bending moment becomes shorter (L < La). Therefore, when the object 110 collides with the shared panel 20, the upward deflection of the shared panel 20 can be reduced.

[0032] Moreover, according to the embodiments described above, the shared panel 20 is sandwiched between the upper reinforcing member 61 and the lower reinforcing member 62. When an object 110 collides with the shared panel 20 from below the vehicle, as shown by the arrow F1 in FIG. 2, a force for the shared panel 20 to move away from the upper / lower reinforcing members 61, 62 is generated. That is, the shared panel 20 tends to move toward the collided object 110 side. However, according to the embodiments described above, since the shared panel 20 is sandwiched between the upper reinforcing member 61 and the lower reinforcing member 62, the movement of the shared panel 20 with respect to the upper / lower reinforcing members 61, 62 can be restricted. Therefore, the upward deflection of the shared panel 20 can be reduced.

[0033] Furthermore, according to the embodiments described above, it is not necessary to adhere or join the upper reinforcing member 61 to the outer cross member 18 and the shared panel 20. Similarly, it is not necessary to adhere or join the lower reinforcing member 62 to the shared panel 20. Therefore, the upper / lower reinforcing members 61, 62 can be incorporated into the vehicle 12 relatively easily.

[0034] Next, another embodiment will be described. Fig. 3 is a cross-sectional view showing the bolt region 66a of the upper / lower reinforcing members 61, 62A in this another embodiment, and Fig. 4 is a cross-sectional view showing the non-bolt region 67a of the upper / lower reinforcing members 61, 62A in this another embodiment. In this embodiment, the lower surface of the lower reinforcing member 62A has a recess 68 into which the entire head 81 of the bolt 80 fits. That is, like the upper reinforcing member 61, the lower reinforcing member 62A has a dish-shaped cross-section (concave cross-section) that opens downward and extends in the vehicle width direction. The head 81 of the bolt 80 is located on the lower surface of the recess 68 of the lower reinforcing member 62A. The other configurations are the same as those of the embodiment described using Figs. 1 and 2.

[0035] According to this embodiment, the heads 81 of the bolts 80 do not protrude from the underside of the vehicle, which is expected to improve the aerodynamic performance of the vehicle. Note that the lower surface of the lower reinforcing member 62A may have a recess 68 into which only a portion of the heads 81 of the bolts 80 extend. [Explanation of symbols]

[0036] 12 vehicle, 14 floor, 16 battery pack, 18 outer cross member, 20 share panel, 22 convex portion (protruding portion), 26 front end, 27 rear end, 28 left end, 29 right end, 30 battery module, 32 case, 34 top plate, 36 bottom plate, 40 inner cross member, 41 web, 42 flange, 43 arm, 51 lower wall (web), 52 flange, 53 arm, 55 end, 61 upper reinforcement member, 62, 62A lower reinforcement member, 64 bolt through hole, 68 recess, 66, 66a bolt area, 67, 67a non-bolt area, 75 end, 80 bolt, 81 head, 82 nut (weld nut), 110 object.

Claims

1. A vehicle underbody structure, a battery pack having a case for accommodating a battery module therein and mounted below the floor; a plurality of outer cross members located below the bottom plate of the case and arranged at intervals in the vehicle front-rear direction, Each of the outer cross members has a hat-shaped cross section that is open upward, extends in the vehicle width direction, and is attached to an outer surface of the bottom plate of the case, An upper reinforcing member having a dish-shaped cross section that opens downward and extends in the vehicle width direction is disposed on the lower surface of the lower wall of each outer cross member, a shear panel covering the bottom plate of the case is disposed below the plurality of upper reinforcing members, The shear panel is bent so as to contact the lower surfaces of the upper reinforcing members, thereby forming convex portions at positions corresponding to the upper reinforcing members, A lower reinforcing member extending in the vehicle width direction is disposed on the inside of each of the protruding portions of the share panel, the lower reinforcing member, the shear panel, the upper reinforcing member, and the lower wall of the outer cross member are stacked and fastened together with bolts at intervals in the vehicle width direction, Both ends of the lower surface of the upper reinforcing member in the vehicle front-rear direction are located outward from both ends of the lower wall of the outer cross member in the vehicle front-rear direction. A vehicle bottom structure characterized by:

2. 2. The vehicle underbody structure according to claim 1, the bolt has a head located on the lower surface of the lower reinforcing member and is fastened to a nut disposed on the upper surface of the lower wall of the outer cross member, The lower surface of the lower reinforcing member has a recess into which at least a part of the head of the bolt fits. A vehicle bottom structure characterized by:

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