Vehicle battery pack structure

Abstract

To provide a structure of a vehicular battery pack, in which torsional rigidity is ensured while a battery pack is lightened in weight and the deformation of a battery case due to side collision, etc. can be suppressed.SOLUTION: A battery case of a battery pack 1 includes a bottom face 12 and a side wall 13 projecting above a vehicle from each of both sides of the bottom face 12 and extending in a front-back direction. An inner cross member 20 extending in a width direction is provided inside the battery case. The inner cross member 20 is joined to the bottom face 12 and the side walls on both sides. The length H1 of the inner cross member 20 in the vehicle vertical direction is set longer than the length L1 in the front-back direction. The inner cross member 20 and the bottom face 12 configure a closed cross-section structure as viewed in the width direction.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] An electric vehicle includes a battery pack, as disclosed in, for example, Patent Document 1. The battery pack includes a battery case that houses a battery module, and the battery case is fixed to the underside of a floor portion of the vehicle body. In order to extend the driving range of an electric vehicle, it is necessary to increase the capacity of the battery pack. Therefore, there is a demand for a larger battery pack.

[0003] On the other hand, in order to avoid an increase in weight due to an increase in size of a battery pack, it is necessary to reduce the weight of the battery case while ensuring a certain rigidity and strength. For example, the battery pack disclosed in Patent Document 1 includes an outer frame that supports the battery case, and the outer frame includes two opposing frame units, and three cross members made of aluminum alloy extruded hollow shapes are provided at intervals so as to connect the lower sides of the frame units. The number of cross members is appropriately determined according to the strength and rigidity characteristics required for the outer frame, together with specifications such as the thickness, cross-sectional shape, and alloy type of the hollow shapes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-133044 A Summary of the Invention [Problem to be solved by the invention]

[0005] By providing an outer frame as in the above example, it is possible to stably support the battery case. However, in a structure like the above example in which a cross member is attached to the underside of a frame unit extending in the vehicle's fore-and-aft direction, the strength and rigidity are insufficient against a side collision (hereinafter referred to as a side impact) in which an object strikes the side of the vehicle body from the outside in the vehicle width direction, and it may be difficult to suppress deformation of the battery case.

[0006] In addition, as the battery pack becomes larger, the area occupied by the battery pack under the floor increases, and there are cases where it is not possible to secure space to place a framework member for reinforcing the floor. Therefore, the battery pack is also required to have torsional rigidity. In the structure of the above example, there is room for improvement in terms of reducing the weight of the battery pack while ensuring torsional rigidity and suppressing deformation of the battery case due to a side collision or the like.

[0007] The present invention has been made to solve the above-mentioned problems, and its object is to provide a vehicle battery pack structure that is lightweight while ensuring torsional rigidity, and can suppress deformation of the battery case due to a side collision, etc. [Means for solving the problem]

[0008] The vehicle battery pack structure according to the present invention for achieving the above object includes a battery case attached to a vehicle underside of a floor of a vehicle body, the battery case of the vehicle battery pack having a plate-shaped bottom surface extending in the vehicle longitudinal direction and side wall portions extending in the vehicle longitudinal direction and protruding from both sides in the vehicle width direction of the bottom surface toward the vehicle upper side, an inner cross member extending in the vehicle width direction is provided within the battery case, the inner cross member is joined to the bottom surface and both side wall portions, the length of the inner cross member in the vehicle vertical direction is set to be longer than the length of the inner cross member in the vehicle longitudinal direction, and the inner cross member and the bottom surface form a closed cross-sectional structure when viewed in the vehicle width direction. An outer cross member extending in the vehicle width direction is provided on the underside of the bottom portion, and the length of the outer cross member in the vehicle front-rear direction is set longer than the length of the inner cross member in the vehicle front-rear direction, the inner cross member and the outer cross member form a T-shape when viewed in the vehicle width direction, the T-shape extends along the vehicle width direction of the battery case, the length of the outer cross member in the vehicle width direction is set longer than the length of the battery case in the vehicle width direction, a battery side member extending in the vehicle front-rear direction is joined to the outer portion of the battery case in the vehicle width direction, and the outer portion of the outer cross member in the vehicle width direction is joined to a lower portion of the battery side member. There are. Effect of the Invention

[0009] According to the present invention, it is possible to ensure torsional rigidity of a battery pack while reducing its weight, and further to suppress deformation of the battery case due to a side collision or the like. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view of a vehicle battery pack according to the present invention, as viewed from above the vehicle. [Diagram 2] 2 is a perspective view showing a state in which an upper case and a battery cell are removed from the battery case in FIG. 1. [Diagram 3] 2 is a perspective view of the battery pack in FIG. 1 as viewed from below the vehicle. [Figure 4] FIG. 2 is a perspective view showing a cross section taken along the line AA in FIG. [Diagram 5] 2 is an enlarged cross-sectional view showing a part of the cross section taken along the line BB in FIG. 1; [Figure 6] FIG. 3 is a perspective view showing a cross section taken along the line CC in FIG. 2. [Figure 7] 5 is an enlarged perspective view of the periphery of the outer member of FIG. 4. [Figure 8] FIG. 3 is a perspective view showing a cross section taken along the line DD in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, one embodiment of the structure of a vehicle battery pack according to the present invention will be described with reference to the drawings (FIGS. 1 to 8). In the drawings, the direction of the arrow Fr indicates the front in the vehicle longitudinal direction. The "front (front end) and rear (rear end)" in the description of the embodiment correspond to the front and rear in the vehicle longitudinal direction. The directions of the arrows L and R indicate the left and right in the vehicle width direction. In addition, the "left and right" in the description of the present embodiment correspond to the left and right when an occupant in the vehicle cabin faces forward of the vehicle.

[0012] The vehicle battery pack 1 of this embodiment is disposed on the vehicle lower side of the floor portion of the vehicle body.

[0013] As shown in Figures 1 to 5, the battery pack 1 of this embodiment has a battery case 10 that accommodates battery cells 1A, a battery side member 30 provided on the outer side of the battery case 10 in the vehicle width direction, an inner cross member 20 arranged inside the battery case 10, and an outer cross member 25 attached to the outside of the lower case 11.

[0014] First, a description will be given of the battery case 10 of the battery pack 1. The battery case 10 is disposed on the vehicle lower side of a floor panel (not shown) of the floor portion of the vehicle body, and is fixed to a side sill (not shown) or the like via a battery side member 30. As shown in FIG. 1, the battery case 10 has a lower case 11 and an upper case 17.

[0015] As shown in Fig. 2, the lower case 11 has a bottom surface portion 12, side wall portions 13, a front wall portion 14, and a rear wall portion 15. The bottom surface portion 12 is a portion on which the battery cells 1A are installed, and has a generally rectangular shape extending in the vehicle front-rear direction. The side wall portions 13 are provided on both outer sides of the bottom surface portion 12 in the vehicle width direction, protrude upward from the outer ends of the bottom surface portion 12 in the vehicle width direction, and extend in the vehicle front-rear direction. A lower outer flange 13a protruding outward in the vehicle width direction is provided at the upper end of the side wall portion 13.

[0016] The front wall portion 14 protrudes from the front end of the bottom surface portion 12 upward in the vehicle and extends in the vehicle width direction. In addition, the outer portion of the front wall portion 14 in the vehicle width direction is connected to the front portion of the side wall portion 13. A bracket 75 or the like that is connected to a framework member such as a front side member is joined to the front surface of the front wall portion 14. The rear wall portion 15 protrudes from the rear end of the bottom surface portion 12 upward in the vehicle and extends in the vehicle width direction. In addition, the outer portion of the rear wall portion 15 in the vehicle width direction is connected to the rear portion of the side wall portion 13. A front flange 14a that protrudes forward of the vehicle and extends in the vehicle width direction is provided at the upper end of the front wall portion 14 of the lower case 11, and a rear flange 15a that protrudes rearward of the vehicle and extends in the vehicle width direction is provided at the upper end of the rear wall portion 15.

[0017] As shown in FIG. 1, the upper case 17 is a lid-like member that covers the lower case 11 from above the vehicle. The upper case 17 in this example has a top surface portion 18, side walls 19, a front wall portion 19a, and a rear wall portion 19b. The top surface portion 18 is disposed at an interval on the vehicle upper side of the bottom surface portion 12 of the lower case 11, and is disposed at a slight interval from the lower surface of the floor panel 71, and has a substantially rectangular shape extending in the vehicle front-rear direction. The side walls 19 of the upper case 17 are provided on both outer sides of the top surface portion 18 in the vehicle width direction, protrude from the outer end of the top surface portion 18 in the vehicle width direction toward the lower side of the vehicle, and extend in the vehicle front-rear direction. The lower end of the side walls 19 of the upper case 17 is provided with an upper outer flange 18a that protrudes outward in the vehicle width direction. The upper outer flange 18a is fastened to the lower outer flange 13a by a bolt or the like.

[0018] The front wall 19a of the upper case 17 protrudes downward from the front end of the top surface 18 and extends in the vehicle width direction. The outer side of the front wall 19a in the vehicle width direction is connected to the front part of the side wall 19. The rear wall 19b of the upper case 17 protrudes downward from the rear end of the top surface 18 and extends in the vehicle width direction. The outer side of the rear wall 19b in the vehicle width direction is connected to the rear part of the side wall 19. The front wall 19a and the rear wall 19b of the upper case 17 are each provided with a flange 19c, similar to the front wall 14 and the rear wall 15 of the lower case 11. The flanges 19c of the upper case 17 are fastened to the front flange 14a and the rear flange 15a of the lower case 11 by bolts or the like, respectively.

[0019] As shown in Figures 2, 4 and 8, the inner cross member 20 is a member extending in the vehicle width direction, with the lower part of the inner cross member 20 joined to the bottom surface 12 of the lower case 11, and the outer end part of the inner cross member 20 in the vehicle width direction abutting the inner surface of the side wall portion 13, with the edge of the end part being joined to the inner surface.

[0020] In this embodiment, a plurality of inner cross members 20 are arranged at intervals from one another in the vehicle longitudinal direction. Although not shown in the figure, the battery cell 1A is arranged between the inner cross members 20 aligned in the vehicle longitudinal direction. Each inner cross member 20 has a predetermined width (L1 in FIG. 5) in the vehicle longitudinal direction, and its height (H1 in FIG. 5) in the vehicle vertical direction is set to be longer than this width. In addition, the inner cross member 20 and the bottom surface portion 12 of the lower case 11 form a closed cross-sectional structure when viewed in the vehicle width direction.

[0021] In this embodiment, three inner cross members 20 are provided inside the battery case 10, and the foremost inner cross member 20 is disposed on the vehicle rear side of the front wall portion 14 of the lower case 11 with a gap therebetween. The middle inner cross member 20 is disposed on the vehicle rear side of the foremost inner cross member 20 with a gap therebetween, and the last inner cross member 20 is disposed on the vehicle rear side of the middle inner cross member 20 with a gap therebetween. The rear wall portion 15 of the lower case 11 is disposed on the vehicle rear side of the last inner cross member 20 with a gap therebetween.

[0022] The inner cross member 20 of this embodiment has an intermediate member 21 and left and right outer members 22. As shown in Figures 2, 5 and 6, the intermediate member 21 is a member that extends in the vehicle width direction as a whole, and has a front panel 21A and a rear panel 21B that are arranged at the front and rear of the vehicle, and these are joined to each other. The front panel 21A has a front wall 21a facing the front of the vehicle, an upper surface portion 21c that protrudes from the upper end of the front wall 21a toward the rear of the vehicle, and an upper front flange 21b that protrudes upward from the front end of the upper surface portion 21c. In addition, a lower front flange (front flange) 21d that protrudes from the lower end toward the front of the vehicle is provided at the lower end of the front wall 21a of the front panel 21A.

[0023] 5 to 8, the rear panel 21B has a rear wall 21e facing the rear of the vehicle, and an upper rear flange 21f protruding from an upper end of the rear wall 21e toward the upper side of the vehicle. In addition, a lower rear flange (rear flange) 21g is provided at the lower end of the rear wall 21d of the rear panel 21B, protruding from the lower end toward the rear of the vehicle.

[0024] The upper front flange 21b of the front panel 21A and the upper rear flange 21f of the rear panel 21B are joined by spot welding or the like to form the intermediate member 21. Furthermore, the lower front flange 21c of the front panel 21A and the lower rear flange 21g of the rear panel 21B are joined to the bottom surface portion 12 of the lower case 11 by spot welding or the like. As a result, the intermediate member 21 and the bottom surface portion 12 form the above-mentioned closed cross-sectional structure. Furthermore, an opening is formed at an end portion of the intermediate member 21 in the vehicle width direction.

[0025] The distance in the vehicle up-down direction from the bottom surface portion 12 of the lower case 11 to the upper surface portion 21e of the intermediate member 21 is set to be longer than the distance in the vehicle front-rear direction between the front wall 21a and the rear wall 21d of the intermediate member 21. That is, the intermediate member 21 has a U-shaped cross section extending in the vehicle up-down direction when viewed in the vehicle width direction, and the above-mentioned closed cross-sectional structure extends in the vehicle up-down direction.

[0026] As shown in FIGS. 5 to 8, the outer member 22 is joined to an outer portion of the intermediate member 21 in the vehicle width direction, and an outer end of the outer member 22 is joined to the side wall portion 13 of the lower case 11.

[0027] The outer member 22 is an annular member formed by joining two members and penetrating in the vehicle width direction. The cross-sectional shape as viewed in the vehicle width direction is an ellipse extending in the vertical direction on the vehicle. The inner side in the vehicle width direction of the outer member 22 is joined to the front wall of the front panel and the rear wall of the rear panel of the intermediate member 21 by spot welding or the like. That is, the inner side in the vehicle width direction of the outer member 22 is inserted into an opening at the outer end in the vehicle width direction of the intermediate member 21, and is sandwiched and held between the front wall and the rear wall of the intermediate member 21 and welded.

[0028] The lower part of the outer member 22 is disposed at a distance from the bottom surface portion 12 on the vehicle upper side, and extends substantially parallel to the bottom surface portion 12. The upper end of the outer member 22 extends so as to incline upwardly of the vehicle as it approaches the outer side in the vehicle width direction. That is, the outer member 22 is substantially trapezoidal in front view, as shown in Figs. 2, 4 and 7. By configuring the outer member 22 as described above, it is easy to manufacture. In addition, the edge of the end part of the outer part in the vehicle width direction of the outer member 22 is joined in contact with the side wall part 13 of the lower case 11 via a reinforcing member 51 described later.

[0029] By providing the inner cross member 20 inside the battery case 10 as described above, deformation of the battery case 10 in response to input of an impact load due to a side collision or the like can be suppressed, and damage to the battery cells 1A built into the battery case 10 can be suppressed. Furthermore, by arranging multiple inner cross members 20, it becomes possible to make the battery case 10 less likely to deform in response to input of an impact load due to a side collision. Furthermore, by arranging multiple inner cross members 20, the rigidity of the battery pack 1 against torsion can be improved, and as a result, the rigidity of the vehicle body can be improved.

[0030] 3, the outer cross member 25 is a member joined to the lower surface side of the bottom portion 12 of the lower case 11, i.e., to the outside of the lower case 11, and extends in the vehicle width direction. In this example, multiple outer cross members 25 are arranged at intervals from each other in the vehicle front-rear direction.

[0031] The outer cross member 25 is a plate having a predetermined width in the vehicle front-rear direction. The distance between the front end and the rear end of the outer cross member 25 (length in the vehicle front-rear direction, L2 in FIG. 5) is set to be longer than the distance between the front wall and the rear wall of the inner cross member 20 (length in the vehicle front-rear direction) L1. In detail, the front end of the outer cross member 25 is disposed on the vehicle front side of the front end of the lower front flange 21d of the inner cross member 20, and the rear end of the outer cross member 25 is disposed on the vehicle rear side of the rear end of the lower rear flange 21g of the inner cross member 20. That is, the inner cross member 20 and the outer cross member 25 form a T-shape when viewed in the vehicle width direction. The T-shape extends along the vehicle width direction.

[0032] 5 and 6, the vehicle width direction outer end of the outer cross member 25 is disposed outboard in the vehicle width direction of the side wall portion 13 of the lower case 11. In this example, it is disposed inside the vehicle width direction outer end of the side sill 50 and slightly inside the outer end of the battery side member 30. In addition, since the outer cross member 25 is disposed so as to overlap with the inner cross member 20 in a plan view, the joint surfaces of the lower front flange and lower rear flange of the inner cross member 20 and the outer cross member 25 may be joined in three pieces via the bottom surface portion 12 of the lower case 11.

[0033] In this way, the inner cross member 20 and the outer cross member 25 are arranged in a T-shape and joined to the bottom surface portion 12, thereby making it possible to improve the torsional rigidity of the inner cross member 20 and the outer cross member 25. This makes it possible to increase the strength of the battery pack 1 against the input of an impact load in the vehicle width direction, thereby improving the reinforcing effect of the battery pack 1.

[0034] In this embodiment, a first distance (H1 in FIG. 5) from the bottom surface 12 of the lower case 11 to the upper end of the inner cross member 20 in the vehicle vertical direction is set to be 3 / 4 or more of a second distance (H2 in FIG. 5) from the bottom surface 12 to the top surface 18 of the upper case 17. More preferably, the first distance H1 is 5 / 6 or more of the second distance H2.

[0035] By setting the inner cross member 20 to a sufficient height relative to the size of the battery case 10 (particularly the vertical dimension), the inner cross member 20 can obtain sufficient strength and rigidity without significantly reducing the installable volume of the battery cells 1A within the battery case 10.

[0036] In addition, in this embodiment, the vehicle width direction end of the outer member 22 of the inner cross member 20 is provided with a joint surface extending in the fore-and-aft direction of the vehicle, and the joint surface is joined to the inner surface of the side wall portion 13 of the lower case 11.

[0037] A plate-shaped reinforcing member 51 extending in the vehicle front-rear direction is joined to an outer end in the vehicle width direction of the annular outer member 22 extending in the vehicle width direction. As shown in Fig. 8, the outer edge of the outer member 22 is welded to the reinforcing member plate 51. The outer surface of the reinforcing member 51, i.e., the surface facing the inner surface of the side wall portion 13, serves as a joint surface, and this joint surface is joined to the inner surface of the side wall portion 13 by spot welding or the like. In this example, the front end of the reinforcing member 51 is disposed further forward of the front end of the outer member 22, and the rear end of the reinforcing member 51 is disposed further rearward of the rear end of the outer member 22.

[0038] By providing the reinforcing members 51 so as to extend from the front and rear of the outer member 22 of the inner cross member 20 and setting a joint surface on the reinforcing members 51, it becomes possible to disperse stress at the joint surface and suppress peeling of the joint. In addition, it is possible to receive the impact load due to a side collision over a wider area, and the load can be reliably received by the inner cross member 20, making it possible to more reliably protect the battery cells 1A.

[0039] 1 and 7, a battery side member 30 which is a hollow member and extends in the vehicle front-rear direction is provided on the vehicle width direction outer side of the side wall portion 13 of the lower case 11 of the battery case 10. The battery side member 30 has a substantially rectangular closed cross-sectional structure which extends in the vehicle up-down direction when viewed in the vehicle front-rear direction.

[0040] As shown in Fig. 7, the battery side member 30 has a first side member 31 extending in the vehicle front-rear direction and a second side member 32 extending in the vehicle front-rear direction. The first side member 31 and the second side member 32 are joined to each other, the first side member 31 is joined to a side sill (not shown), and the second side member 32 is a hollow member joined to the outer surface of the side wall portion 13 of the lower case 11 of the battery case 10. A hat-shaped member 80 is provided inside the second side member 32 to reinforce the second side member 32. By providing the battery side member 30, the rigidity of the side wall portion 13 can be improved.

[0041] The description of the present embodiment is merely an example for explaining the present invention, and does not limit the invention described in the claims. Furthermore, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications are possible within the technical scope described in the claims.

[0042] In this embodiment, the inner cross member 20 is made up of the intermediate member 21 and the left and right outer members 22, but is not limited to this. It may be made up of a single member. [Explanation of symbols]

[0043] 1 Battery pack 1A Battery Cell 10 Battery case 11 Lower case 12 Bottom part 13 Side wall 13a Lower outer flange 14 Front wall 14a Front flange 15 Rear wall 15a Rear flange 17 Upper case 18 Top section 18a Upper outer flange 19 Side wall 19a Front wall 19b Rear wall 20 Inner cross member 21 Intermediate parts 21A Front Panel 21a Front wall 21b Upper front flange 21c Lower front flange (front flange) 21B Rear Panel 21d back wall 21e Top part 21f Upper rear flange 21g Lower rear flange (rear flange) 22 Outer member 25 Outer cross member 30 Battery side member 31 First side member 32 Second side member 51 Reinforcement member 75 Bracket 80 Hat-shaped component

Claims

1. A vehicle battery pack structure having a battery case attached to a vehicle underside of a floor portion of a vehicle body, The battery case has a plate-shaped bottom surface portion extending in a vehicle front-rear direction, and side wall portions protruding upward from both sides of the bottom surface portion in a vehicle width direction and extending in the vehicle front-rear direction, An inner cross member extending in a vehicle width direction is provided in the battery case, and the inner cross member is joined to the bottom surface portion and the side wall portions on both sides, The length of the inner cross member in the vertical direction of the vehicle is set to be longer than the length of the inner cross member in the front-rear direction of the vehicle, The inner cross member and the bottom surface portion form a closed cross-sectional structure when viewed in the vehicle width direction, An outer cross member extending in the vehicle width direction is provided on the lower surface side of the bottom surface portion, The length of the outer cross member in the vehicle front-rear direction is set to be longer than the length of the inner cross member in the vehicle front-rear direction, The inner cross member and the outer cross member form a T-shape when viewed in the vehicle width direction, and the T-shape extends along the vehicle width direction of the battery case, The length of the outer cross member in the vehicle width direction is set to be longer than the length of the battery case in the vehicle width direction, A battery side member extending in a vehicle front-rear direction is joined to an outer portion of the battery case in a vehicle width direction, A structure of a vehicle battery pack, characterized in that an outer portion of the outer cross member in the vehicle width direction is joined to a lower portion of the battery side member.

2. The battery case has a top surface portion disposed above the bottom surface portion of the vehicle with a gap therebetween, 2. The structure of a vehicle battery pack as described in claim 1, characterized in that a first distance from the bottom surface portion to the upper end of the inner cross member in the vehicle vertical direction is set to be greater than or equal to 3 / 4 of a second distance from the bottom surface portion to the top surface portion.

3. 3. The structure of a vehicle battery pack as described in claim 1 or claim 2, characterized in that the vehicle width direction end of the inner cross member is provided with a joint surface extending in the fore-and-aft direction of the vehicle, and the joint surface is joined to the inner surface of the side wall portion.

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