Structure for mounting battery pack in vehicle

Abstract

To provide a structure for mounting a battery pack in a vehicle, by which a downward projecting deformation of a floor panel can be prevented when a load is input to a fuel tank.SOLUTION: A structure for mounting a battery pack in a vehicle, according to the present invention is a structure for mounting a battery pack on a vehicle frame member from below a floor panel of the vehicle, the battery pack having a lower case and an upper case and accommodating a battery module including a plurality of battery cells; wherein a fuel tank mounted on the vehicle frame member at a first mounting portion is disposed behind the battery pack; wherein the battery pack is mounted on the vehicle frame member at a second mounting portion in an end area on a rear side; wherein a reinforcing member mounted on a side plate of the lower case located on the rear side is provided inside the lower case; and wherein the reinforcing member includes a support member extending in a vehicle height direction and being in contact with a top plate of the upper case, between the first mounting portion and the second mounting portion in a vehicle fore-aft direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle mounting structure for a battery pack. [Background technology]

[0002] Patent Document 1 discloses a reinforcement provided on the rear end side of a battery pack. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-111787 Summary of the Invention [Problem to be solved by the invention]

[0004] In a vehicle that has a fuel tank at the rear end of the battery pack, there is a risk that the floor panel will be deformed downward in a convex manner when a load is applied to the fuel tank.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a vehicle mounting structure for a battery pack that can suppress downward convex deformation of the floor panel when a load is input to the fuel tank. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the vehicle mounting structure for a battery pack of the present invention is provided with a lower case and an upper case, and a battery pack accommodating a battery module including a plurality of battery cells is attached to a vehicle frame member from below a floor panel of the vehicle, wherein a fuel tank is arranged behind the battery pack in the vehicle fore-and-aft direction and attached to the vehicle frame member by a first mounting portion, and the battery pack is attached to the vehicle frame member at an end region on the rear side by a second mounting portion, and a reinforcing member is provided inside the lower case and attached to a side panel of the lower case, located on the rear side in the vehicle fore-and-aft direction, and the reinforcing member has a support member that extends in the vehicle height direction and contacts the top panel of the upper case between the first mounting portion and the second mounting portion in the vehicle fore-and-aft direction. [Effects of the Invention]

[0007] The vehicle mounting structure for a battery pack according to the present invention has the effect of suppressing downward convex deformation of the floor panel that occurs between the first mounting portion and the second mounting portion when a load is input to the fuel tank. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a top view of a portion of a vehicle mounting structure for a battery pack according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along the line AA in FIG. [Figure 3] FIG. 3 is a diagram showing the state at the initial stage of a rear-end collision. [Figure 4] FIG. 4 is a diagram showing a state where the collision has progressed further than the initial collision stage. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the battery pack mounting structure for a vehicle according to the present invention will be described, but the present invention is not limited to these embodiments.

[0010] Fig. 1 is a diagram showing a part of a vehicle mounting structure for a battery pack 3 according to an embodiment, as viewed from above. Fig. 2 is a diagram showing a cross section taken along line AA in Fig. 1.

[0011] "Fr" in FIGS. 1 and 2 indicates the front side in the vehicle longitudinal direction, which is a first direction. The first direction is not limited to the vehicle longitudinal direction but also includes the longitudinal direction of the battery pack 3, and in this embodiment, it is also the horizontal direction. "RH" in FIG. 1 indicates the right side in the vehicle width direction, which is a second direction perpendicular to the first direction. The second direction is not limited to the vehicle width direction but also includes the width direction of the battery pack 3, and in this embodiment, it is also the horizontal direction. "UPR" in FIG. 2 indicates the upper side in the vehicle height direction, which is a third direction perpendicular to the first and second directions. The third direction is not limited to the vehicle height direction but also includes the height direction of the battery pack 3, and in this embodiment, it is also the vertical direction.

[0012] As shown in FIGS. 1 and 2 , a battery pack 3 is mounted on a vehicle and serves as a power supply source for supplying power to, for example, a motor, which is one of the vehicle's drive sources. The battery pack 3 according to this embodiment is disposed below a floor panel 5 of the vehicle and includes a battery case 30 composed of a lower case 31 and an upper case 32 facing each other in the vehicle height direction. The lower case 31 includes a bottom plate 31a, side plates 31b, and a flange portion 311. The upper case 32 includes a top plate 32a, side plates 32b, and a flange portion 321. The lower case 31 and the upper case 32 are fastened to each other at the flange portions 311 and 321 on their respective peripheries by fastening members (not shown). The battery case 30 accommodates multiple battery stacks 1A and 1B, each including multiple battery cells. While FIG. 1 shows two battery stacks 1A and 1B, at least one more battery stack may be disposed forward of the battery stack 1A in the vehicle longitudinal direction.

[0013] In this embodiment, brackets 2 are attached to both sides of the battery case 30 (upper case 32) in the vehicle width direction. The brackets 2 are arranged so as to be located to the sides (left and right in the vehicle width direction) of the battery stack 1B, which is arranged at the rearmost part of the battery case 30 in the vehicle front-rear direction. The brackets 2 are attached to a vehicle frame member (not shown) via the floor panel 5 at the second attachment portion P2 by fastening with bolts and nuts (not shown). As a result, the battery pack 3 (battery case 30) is attached to the vehicle frame member (not shown) at the second attachment portion P2 via the brackets 2 in the end region on the rear side in the vehicle front-rear direction.

[0014] Further, a first reinforcing reinforcement 61 is provided inside the battery case 30. The first reinforcing reinforcement 61 is a first reinforcing member that is disposed in a collision prevention area AR1 between the battery stack 1B and the lower case 31, rearward of the second mounting portion P2 in the vehicle longitudinal direction, and has a lower end portion 61a and an upper end portion 61b joined to the lower case 22 by welding or the like. Further, a second reinforcing reinforcement 62 is provided outside the battery case 30. The second reinforcing reinforcement 62 is a second reinforcing member that is disposed rearward of the second mounting portion P2 in the vehicle longitudinal direction, facing the first reinforcing reinforcement 61 with the lower case 31 in between, and has a lower end portion 62a and an upper end portion 62b joined to the lower case 31 by welding or the like. The joining positions of the lower end portion 61a of the first reinforcing reinforcement 61 and the lower end portion 62a of the second reinforcing reinforcement 62 to the bottom plate 31a of the lower case 31 overlap when viewed from the vehicle height direction. Furthermore, the joining positions of the upper end portion 61b of the first reinforcing reinforcement 61 and the upper end portion 62b of the second reinforcing reinforcement 62 to the side plate 31b of the lower case 31 overlap when viewed from the vehicle front-rear direction.

[0015] The lower end 10a of the support member 10 is attached in contact with the upper surface 61c of the first reinforcing reinforcement 61. The support member 10 is a support member that extends in the vehicle height direction (vertical direction) and has its upper end 10b abutting against and making contact with the top plate 32a of the upper case 32. Note that the upper end 10b of the support member 10 is not limited to being in contact with the top plate 32a, and may be configured to extend to a position higher than the upper surface of the battery stack 1B, for example, to minimize the gap between the upper end 10b of the support member 10 and the top plate 32a of the upper case 32.

[0016] A fuel tank 4 that stores fuel to be supplied to the engine, which is one of the driving sources of the vehicle, is disposed behind the battery pack 3 in the vehicle longitudinal direction. The fuel tank 4 is disposed below a floor panel 5, and is attached at a first attachment portion P1 via the floor panel 5 to a mounting seat 7 provided on a vehicle frame member (not shown) by fastening a flange portion 40 with bolts 8 and nuts 9.

[0017] FIG. 3 shows the state during the initial stage of a rear-end collision. During the initial stage of a rear-end collision, the floor panel 5 moves forward due to the rear-end collision. However, the second mounting portion P2 of the bracket 2 acts to restrain the forward movement of the floor panel 5, serving as a fulcrum for deformation of the floor panel 5. The portion of the floor panel 5 located rearward of the second mounting portion P2 is pushed in from behind, causing the floor panel 5 to deform downward. The portion of the floor panel 5 that deforms downward convexly comes into contact with the top plate 32a of the upper case 32 rearward of the battery stack 1B and is pushed downward. However, because the upper case 32 is supported from below by the support member 10, deformation of the upper case 32 can be suppressed. As a result, when the floor panel 5 deforms downward convexly due to the rear-end collision, the upper case 32 is pushed by the floor panel 5 and deforms downward convexly, preventing contact with the battery stack 1B. This also serves to suppress the forward movement of the floor panel 5.

[0018] Additionally, the support provided by the upper case 32 with the support member 10 is effective for supporting deformed portions of the floor panel 5 that deform downward and convexly from between adjacent skeletal members that make up the vehicle body in the fore-and-aft direction. For this reason, it is desirable to dispose the support member 10 between adjacent skeletal members in the fore-and-aft direction of the vehicle. Furthermore, a closed cross section is formed by the lower case 31, the upper case 32, and the support member 10, and this portion where the closed cross section is formed can also be effectively used as support when the vehicle is pushed up or down.

[0019] FIG. 4 shows a state where the fuel tank 4 has penetrated further than at the initial stage of a rear-end collision. As the floor panel 5 is pushed in, causing downward convex deformation, the support pillar member 10 is subjected to a compressive load, and the support pillar member 10 is pressed down from above and below in the vehicle height direction by the top plate 32a of the upper case 32 and the upper surface 61c of the first reinforcing reinforcement 61. Therefore, when the fuel tank 4 penetrates further from the rear to the front and pushes the battery pack 3 in the vehicle longitudinal direction, the support pillar member 10 can function as a beam with both upper and lower ends fixed, thereby utilizing its bending strength. This prevents the battery case 30 (lower case 31 and upper case 32) from coming into contact with the battery stack 1B when pressed by the fuel tank 4.

[0020] In order to prevent the flange portions 311, 321 of the lower case 31 and the upper case 32 from contacting the edges of the fuel tank 4, a bent portion 321a bent downward is provided at the rear end portion of the flange portion 321 of the upper case 32. Furthermore, the back surface 62c of the second reinforcing reinforcement 62 is a stable surface supported by having its lower end portion 62a and its upper end portion 62b joined to the bottom plate 31a and side plate 31b of the lower case 31. For this reason, it is desirable to position the back surface 62c of the second reinforcing reinforcement 62 at the same position as or behind the bent portion 321a of the flange portion 321 of the upper case 32 in the vehicle front-rear direction, thereby expanding the surface contact range when the back surface 62c of the second reinforcing reinforcement 62 comes into contact with the fuel tank 4.

[0021] Furthermore, by increasing the surface contact area between the back surface 62c of the second reinforcing reinforcement 62 and the fuel tank 4 in the vehicle longitudinal direction, it is possible to reduce the surface pressure applied to the fuel tank 4 when the back surface 62c of the second reinforcing reinforcement 62 comes into contact with the fuel tank 4, thereby avoiding damage to the fuel tank 4. At the same time, by transmitting the load to the strong back surface 62c of the second reinforcing reinforcement 62, it is possible to increase the collapse load of the side plate 31b of the lower case 31, and it is possible to reduce the amount of penetration of the fuel tank 4 into the battery pack 3 in the vehicle longitudinal direction.

[0022] Although the lower end 10a of the support member 10 may be attached directly to the bottom plate 31a of the lower case 31 without providing the first reinforcing reinforcement 61, the rigidity of the bottom plate 31a of the lower case 31 is low. This is therefore disadvantageous in preventing deformation of the top plate 32a of the upper case 32 pressed by the floor panel 5 that has deformed convexly downward. Therefore, attaching the lower end 10a of the support member 10 to the upper surface 61c of the first reinforcing reinforcement 61, which has higher rigidity than the bottom plate 31a of the lower case 31, is advantageous in preventing deformation of the top plate 32a of the upper case 32 pressed by the floor panel 5 that has deformed convexly downward. Furthermore, it is preferable to make the support member 10 using a resin material, as this ensures insulation when it comes into contact with the battery stack 1B.

[0023] As described above, the vehicle mounting structure for a battery pack 3 according to the embodiment includes a lower case 31 and an upper case 32. The battery pack 3, which houses battery stacks 1A, 1B including a plurality of battery cells, is mounted to a vehicle frame member from below a floor panel 5 of the vehicle. In addition, in the vehicle mounting structure for a battery pack 3 according to the embodiment, a fuel tank 4 is disposed behind the battery pack 3 in the vehicle longitudinal direction. The fuel tank 4 is mounted to the vehicle frame member at a first mounting portion P1 via a mounting seat 7. The battery pack 3 is mounted to the vehicle frame member at a second mounting portion P2 via a bracket 2 in an end region on the rear side in the vehicle longitudinal direction. A first reinforcing member, a first reinforcing reinforcement 61, is provided inside the lower case 31, located rearward in the vehicle longitudinal direction, and attached to a side plate 31b of the lower case 31. The first reinforcing reinforcement 61 extends in the vehicle height direction (vertical direction) and has a support member 10 which is a support member that contacts the top plate 32a of the upper case 32 between the first mounting portion P1 and the second mounting portion P2 in the vehicle fore-and-aft direction.

[0024] As a result, in the vehicle mounting structure of the battery pack 3 according to the embodiment, downward convex deformation of the floor panel 5 that occurs between the first mounting portion P1 and the second mounting portion P2 can be suppressed when a load is input to the fuel tank 4. [Explanation of symbols]

[0025] 1A, 1B battery stack 3 Battery pack 4 fuel tanks 5 Floor Panel 10 Support member 31 Lower case 32 Upper Case 61 First reinforcement 62 Second Reinforcement

Claims

[Claim 1] The battery pack includes a lower case and an upper case, and houses a battery module including a plurality of battery cells. The battery pack is attached to a vehicle frame member from below a floor panel of the vehicle. A vehicle mounting structure for a battery pack, a fuel tank is disposed behind the battery pack in the vehicle front-rear direction and is attached to the vehicle frame member by a first attachment portion; the battery pack is attached to the vehicle frame member at a second attachment portion in the rear end region, a reinforcing member attached to a side plate of the lower case is provided inside the lower case and positioned rearward in the vehicle front-rear direction; the reinforcing member has a support member that extends in a vehicle height direction and contacts a top plate of the upper case between the first mounting portion and the second mounting portion in the vehicle front-rear direction; A vehicle mounting structure for a battery pack.

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