Battery pack structure

Abstract

To provide a battery pack structure in which a transmission path of a side collision load is secured upon a side collision of a vehicle.SOLUTION: In a battery case 32, a rib 46 extending between side walls 40 and 42 is provided, so that rigidity of the battery case 32 itself can be improved as compared with a case where the rib 46 is not provided. Further, upon a side collision of a vehicle 12, a side collision load input to a rocker 16 is transmitted to the battery case 32 side through a fastening part 52. The fastening part 52 is provided on an extension line of the rib 46 in a vehicle width direction in a vehicle plan view, so that the side collision load transmitted to the battery case 32 side through the fastening part 52 is transmitted from one side wall 40 side to the rib 46, and is transmitted to the other side wall 42 side.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a battery pack structure.

Background Art

[0002] In the electric vehicle described in the following Patent Document 1, a substantially rectangular parallelepiped battery accommodation space is formed by a space portion constituted by a pair of left and right sill beams (sometimes referred to as rockers), a front cross member, a rear cross member, and a cooling plate, and a plurality of batteries are accommodated in this battery accommodation space. That is, the plurality of batteries are surrounded by a so-called vehicle body frame (sometimes referred to as a vehicle skeleton) constituted by the rockers, the front cross member, and the rear cross member.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] However, in the above-mentioned prior art, there is a concern regarding the transmission path of a side impact load input to a battery pack constituted by a plurality of batteries during a side impact of a vehicle (hereinafter referred to as "vehicle side impact").

[0005] The present invention has been made in view of the above facts, and an object of the present invention is to obtain a battery pack structure in which a transmission path for a side impact load is secured during a side impact of a vehicle.

Means for Solving the Problem

[0006] The battery pack structure according to the invention of claim 1 is: It is formed in a box shape with an opening on the upper side of the vehicle,A battery pack body in which battery cells are housed in a state where they extend along the vehicle width direction and are arranged along the vehicle front-rear direction, A cover is positioned on the vehicle's upper side of the opening of the battery pack body, forming part of the floor inside the vehicle and covering the housing of the battery pack body. In the bottom wall which constitutes a part of the battery pack body, a first rib is provided which protrudes in the vehicle width direction between the battery cells arranged in the vehicle longitudinal direction and spans between a pair of side walls which constitute another part of the battery pack body and extend in the vehicle longitudinal direction at both ends in the vehicle width direction, The cover is provided and The battery pack body is provided with fastening portions located on the outside of its side wall, positioned on the extension of the first rib in the vehicle width direction in a plan view of the vehicle, constituting a part of the vehicle frame, and fastened to rockers that extend along the vehicle longitudinal direction on both outer sides in the vehicle width direction.

[0007] The battery pack structure according to claim 1 comprises a battery pack body, a first rib, and a fastening portion. The battery pack body houses battery cells that extend along the vehicle width direction and are arranged along the vehicle longitudinal direction. The first rib is located on the bottom wall which constitutes a part of the battery pack body, protruding along the vehicle width direction between the battery cells arranged along the vehicle longitudinal direction, and spans between a pair of side walls which constitute another part of the battery pack body and extend along both ends in the vehicle width direction and along the vehicle longitudinal direction.

[0008] Here, the battery pack body is provided with fastening portions on the outside of its side walls. These fastening portions are positioned on the extension of the first rib in the vehicle width direction in a plan view of the vehicle, and constitute part of the vehicle frame. They are fastened to rockers that extend along the vehicle's longitudinal direction on both outer sides in the vehicle width direction.

[0009] In this invention, by providing a first rib that spans a pair of side walls within the battery pack body, it is possible to improve the rigidity of the battery pack body itself compared to a case where the first rib is not provided. As a result, in this invention, bending deformation of the battery pack body is suppressed.

[0010] Furthermore, in this invention, when a vehicle is involved in a side collision, the side impact load input to the rocker is transmitted to the battery pack body via the fastening portion. Since the fastening portion is located on the extension of the first rib in the vehicle width direction in a plan view of the vehicle, the side impact load transmitted to the battery pack body via the fastening portion is transmitted from one side wall to the first rib and then to the other side wall. In this way, this invention ensures a transmission path for the side impact load from one rocker to the other rocker. Furthermore, fastening points are provided on the cover that seals the housing of the battery pack itself. Since this cover forms the floor of the vehicle's interior, there is no need to install a separate floor panel, thus reducing the number of parts.

[0011] The battery pack structure according to claim 2 is the battery pack structure according to claim 1, further comprising a second rib provided on the bottom wall of the battery pack, which transmits a load input along the vehicle width direction to the opposite side in the vehicle width direction along the vehicle width direction.

[0012] In the battery pack structure according to claim 2, a second rib is provided on the bottom wall of the battery pack body, and the second rib is configured to transmit a load (side impact load) input along the vehicle width direction to the opposite side in the vehicle width direction along the vehicle width direction.

[0013] In this way, by providing a second rib on the bottom wall of the battery pack body, it is possible to improve the rigidity of the battery pack body itself compared to a case where the second rib is not provided. The second rib provided on the bottom wall of the battery pack body may be either protruding upward in the vehicle's vertical direction from the bottom wall of the battery pack body, or protruding downward in the vehicle's vertical direction from the bottom wall of the battery pack body.

[0014] The battery pack structure according to claim 3 is the battery pack structure according to claim 2, wherein the second rib protrudes downward from the bottom wall of the battery pack body in the vertical direction of the vehicle and is set to overlap with the rocker when viewed from the side of the vehicle.

[0015] In the battery pack structure according to claim 3, the second rib protrudes downward from the bottom wall of the battery pack body in the vertical direction of the vehicle and is provided outside the battery pack body. As a comparative example, if the second rib protrudes upward from the bottom wall of the battery pack body in the vertical direction of the vehicle, the second rib will be provided inside the housing of the battery pack body. On the other hand, if the second rib protrudes downward from the bottom wall of the battery pack body in the vertical direction of the vehicle, the second rib will be provided on the outside of the battery pack body.

[0016] Therefore, in the present invention, the second rib protrudes downward from the bottom wall of the battery pack body in the vertical direction of the vehicle, which increases the volume inside the housing compared to the case where the second rib is provided inside the housing of the battery pack body.

[0017] Furthermore, if the second rib protrudes downward from the bottom wall of the battery pack body in the vertical direction of the vehicle, the second rib can be set to overlap with the rocker in a side view of the vehicle, thereby enabling the side impact load to be transmitted to the opposite side in the vehicle width direction via the second rib.

[0018] Therefore, the present invention makes it possible to improve the rigidity of the battery pack body while ensuring battery capacity. [Effects of the Invention]

[0021] As described above, the battery pack structure according to the present invention can ensure a transmission path for the side impact load during a side impact of a vehicle. [Brief explanation of the drawing]

[0022] [Figure 1] This is a perspective view from the upper left, showing the configuration of a vehicle to which the battery pack structure according to this embodiment is applied. [Figure 2] This is a plan view showing a partially cutaway view of the configuration of a vehicle to which the battery pack structure according to this embodiment is applied. [Figure 3] It is a schematic cross-sectional view taken along line A-A in FIG. 2. [Figure 4] It is a schematic cross-sectional view taken along line B-B in FIG. 2. [Figure 5] It is a schematic cross-sectional view corresponding to FIG. 3, showing the configuration of a modified example of a vehicle to which the battery pack structure according to the present embodiment is applied. MODE FOR CARRYING OUT THE INVENTION

[0023] A battery pack structure according to an embodiment of the present invention will be described with reference to the drawings. Arrows FR, UP, and RH that are appropriately shown in each drawing respectively indicate the forward direction (traveling direction), upward direction, and rightward direction of a vehicle to which the battery pack structure according to the present embodiment is applied. Hereinafter, when description is simply made using the directions of front-rear, left-right, and up-down, unless otherwise specified, they refer to front and rear in the vehicle front-rear direction, left and right in the vehicle left-right direction (vehicle width direction), and up and down in the vehicle up-down direction. In addition, in each drawing, illustration of some members and some reference numerals may be omitted for the purpose of making the drawings easy to read.

[0024] As shown in FIG. 1, a vehicle (vehicle body) 12 to which the battery pack structure 10 according to the embodiment of the present invention is applied includes a pair of left and right rockers 16, 18 that each constitute a vehicle frame and extend along the vehicle front-rear direction at lower portions of both ends in the vehicle width direction of a vehicle compartment 14 (see FIG. 3), a front cross member 20 provided along the vehicle width direction at the front ends of the rockers 16, 18, and a rear cross member 22 provided along the vehicle width direction at the rear ends of the left and right rockers 16, 18. Front side members 24 each extend along the vehicle front-rear direction on both end sides of the front cross member 20 in the vehicle width direction, and rear side members 26 each extend along the vehicle front-rear direction on both end sides of the rear cross member 22 in the vehicle width direction.

[0025] Furthermore, the vehicle 12 according to this embodiment is an electric vehicle that runs using the driving force of an electric motor (not shown), and a battery pack (battery pack body) 30 containing a plurality of battery cells 28 that supply power for driving the electric motor is provided at the bottom of the vehicle 12.

[0026] (Battery pack structure configuration) Here, the configuration of the battery pack structure according to this embodiment will be described.

[0027] As shown in Figure 1, the battery pack structure 10 according to this embodiment includes a battery pack 30. The battery pack 30 is made of a light metal such as an aluminum alloy and includes a box-shaped battery case (battery pack body) 32 that is rectangular in shape with the vehicle's front-rear direction as its longitudinal direction in a plan view and has an opening at the top. In addition to metal, resin materials such as carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP) may also be used. The same applies to the cover 48 and under cover 60 described later.

[0028] The battery case 32 is composed of a bottom wall 34, a front wall 36 erected from the front end of the bottom wall 34 in the vehicle's longitudinal direction, a rear wall 38 facing the front wall 36 and erected from the rear end of the bottom wall 34 in the vehicle's longitudinal direction, and a pair of side walls 40, 42 erected from both ends of the bottom wall 34 in the vehicle's width direction and facing each other.

[0029] In this embodiment, for example, the distance between the front wall 36 and the rear wall 38 of the battery case 32 is formed to be slightly narrower than the distance between the front cross member 20 and the rear cross member 22. Also, the distance between the side walls 40 and 42 of the battery case 32 is formed to be slightly narrower than the distance between the rockers 16 and 18. As a result, the battery case 32 in this embodiment can be placed within the space enclosed by the rockers 16, 18, the front cross member 20 and the rear cross member 22 that constitute the vehicle frame.

[0030] Furthermore, within the housing section 44 of the battery case 32, which is composed of the bottom wall 34, front wall 36, rear wall 38, and side walls 40 and 42, a plurality of thin, plate-shaped battery cells 28, which form a substantially rectangular shape with the vehicle width direction as the longitudinal direction, are housed, and these battery cells 28 are arranged along the front-rear direction of the vehicle. In this example, the housing section 44 is composed of a single space, but the housing section 44 may be divided into multiple sections.

[0031] On the other hand, a rib (first rib) 46 is provided projecting along the vehicle width direction between adjacent battery cells 28 at approximately the center of the bottom wall 34 of the battery case 32 in the vehicle's longitudinal direction, and this rib 46 spans between the side wall 40 and the side wall 42. Here, for example, the height of the rib 46 is set to be about half the height of the side wall 40, and the height dimension is set to be greater than the length dimension in the vehicle's longitudinal direction, but this is not the only option (as will be described later).

[0032] Furthermore, the housing section 44 of the battery case 32 is covered by a cover 48 that forms a rectangular plate shape in plan view, while housing multiple battery cells 28. This cover 48 is made of a light metal such as aluminum alloy, has a plate shape with the thickness direction in the vertical direction of the vehicle, and is integrated with the battery case 32 by welding or the like.

[0033] The ends (parts) 48A and 48B of the cover 48 in the vehicle width direction protrude outward from the side walls 40 and 42 of the battery case 32 in the vehicle width direction. Furthermore, the ends 48A and 48B of the cover 48 can be fastened to the upper walls 16A and 18A of the rockers 16 and 18, respectively, via fastening parts 50, 52, and 54 arranged along the vehicle's longitudinal direction. Fastening methods at the fastening parts 50, 52, and 54 include bolt fastening, riveting, spot welding, etc. These methods can be appropriately changed depending on the material being fastened.

[0034] In this embodiment, the fastening portion 52 is provided on the extension line of the rib 46 in the vehicle width direction in a plan view of the vehicle. In this embodiment, the fastening portions 50, 52, and 54 provided at both ends 48A and 48B of the cover 48 in the vehicle width direction are formed continuously along the vehicle longitudinal direction, but the fastening portions 50, 52, and 54 may be formed intermittently.

[0035] Meanwhile, ribs (second ribs) 56 and 58 protrude from the bottom wall 34 of the battery case 32 along the vehicle width direction. Multiple ribs 56 and 58 are arranged along the vehicle's longitudinal direction. In this embodiment, rib 56 is provided on the front side of rib 46 in a plan view, and rib 58 is provided on the rear side of rib 46.

[0036] Below the ribs 56 and 58, an under cover 60 is provided, positioned approximately parallel to the bottom wall 34 of the battery case 32. This under cover 60 is made of a light metal such as aluminum alloy, has a plate-like shape with the plate thickness oriented in the vertical direction of the vehicle, and serves to prevent interference with the road surface.

[0037] As shown in Figure 3, the front end 60A of the under cover 60 is fastened to the lower wall 20A of the front cross member 20 via a fastening part 61, and the rear end 60B of the under cover 60 is fastened to the lower wall 22A of the rear cross member 22 via a fastening part 63. The fastening methods for fastening parts 61 and 63 include bolt fastening, riveting, spot welding, etc., as with fastening parts 50, 52, and 54. In addition, spacers 65 are provided at fastening parts 61 and 63 to maintain the gap between the bottom wall 34 of the battery case 32 and the under cover 60.

[0038] Furthermore, as shown in Figure 2, both ends 60C and 60D of the under cover 60 in the vehicle width direction are fastened to the lower wall 18B of the rocker 18 (see Figure 4), and the ribs 56 and 58 are positioned between the rocker 16 and the rocker 18. Note that the rocker 16 and the rocker 18 have substantially the same configuration. For this reason, only the rocker 18 side is shown in Figure 4 as a representative of both.

[0039] As shown in Figure 4, the height of the rib 46 is set to be slightly lower than the side wall 42. By increasing the height of the rib 46 in this way, it becomes possible to form a hollow space inside the rib 46 and route cooling pipes through which a cooling medium for cooling the battery cells 28 flows. In this case, in addition to the cooling pipes, cables, harnesses, and other wiring may also be routed.

[0040] On the other hand, the rocker 18 has a closed section structure with a closed section 66 composed of an outer section 62 and an inner section 64. Within the closed section 66, there is a linearly formed EA section (impact absorbing section) 68 that bridges the outer section 62 and the inner section 64, and a ladder-shaped EA section 70. By providing the EA sections 68 and 70 within the closed section 66 of the rocker 18, the plastic deformation of the EA sections 68 and 70 makes it possible to absorb the side impact load applied during a side collision with the vehicle. The EA section 70 is set to overlap with the rib 46 when viewed from the side of the vehicle.

[0041] Furthermore, the upper wall 18A of the inner portion 64 of the rocker 18 is fastened to the end of the cover 48 in the vehicle width direction, and the lower wall 18B of the inner portion 64 is fastened to both ends 60C and 60D (see Figure 2) of the under cover 60 in the vehicle width direction. Note that the configuration and shape of the rocker 18 are merely examples and are not limited to this configuration and shape.

[0042] (Function and effect of battery pack structure) Next, the operation and effects of the battery pack structure according to this embodiment will be described.

[0043] As shown in Figures 1 and 2, in this embodiment, the battery pack structure 10 comprises a battery case 32, ribs 46, and fastening parts 52. The battery case 32 houses battery cells 28 that extend along the vehicle width direction and are arranged along the vehicle longitudinal direction. The ribs 46 protrude along the vehicle width direction from the bottom wall 34 of the battery case 32 between the battery cells 28 arranged along the vehicle longitudinal direction and are spanned between the side walls 40 and 42 of the battery case 32.

[0044] Thus, in this embodiment, by providing a rib 46 that spans between the side walls 40, 42 inside the battery case 32, it is possible to improve the rigidity of the battery case 32 itself compared to a case where the rib 46 is not provided. As a result, in this embodiment, deflection deformation of the battery case 32 is suppressed.

[0045] Furthermore, in this embodiment, a fastening portion 52 between the cover 48 and the rockers 16 and 18 is provided on the extension of the rib 46 in the vehicle width direction when viewed from above the vehicle. Therefore, in this embodiment, when the vehicle 12 is involved in a side collision, the side collision load input to the rocker 18 is transmitted to the battery case 32 side via the fastening portion 52. Since the fastening portion 52 is provided on the extension of the rib 46 in the vehicle width direction when viewed from above the vehicle, the side collision load transmitted to the battery case 32 side via the fastening portion 52 is transmitted from one side wall 42 to the rib 46 and then to the other side wall 40 side.

[0046] Thus, in this embodiment, a transmission path is secured from one rocker 18 to the other rocker 16 in response to a lateral impact load. Furthermore, by providing the fastening portion 52 between the cover 48 and the rockers 16 and 18 on the extension of the rib 46 in the vehicle width direction in a plan view of the vehicle, the effect of positioning the fastening portion 52 is also obtained.

[0047] Furthermore, the rib 46 is positioned to overlap with the EA section 70, which is located within the closed cross-section 66 of the rocker 18 shown in Figure 4, when viewed from the side of the vehicle. This ensures that the side impact load applied during a vehicle collision can be reliably transmitted to the rib 46 via the EA section 70.

[0048] Furthermore, in this embodiment, as shown in Figure 3, ribs 56 and 58 are provided on the bottom wall 34 of the battery case 32, and these ribs 56 and 58 are configured to transmit lateral impact loads to the opposite side in the vehicle width direction along the vehicle width direction. By providing ribs 56 and 58 on the bottom wall 34 of the battery case 32 in this way, it is possible to improve the rigidity of the battery case 32 itself compared to a case where the ribs 56 and 58 are not provided. In addition, in this embodiment, by providing multiple ribs 56 and 58, it is possible to distribute the lateral impact loads.

[0049] Furthermore, the ribs 56 and 58 provided on the bottom wall 34 of the battery case 32 may be arranged in two ways: either the ribs 56 and 58 protrude upward from the bottom wall 34 of the battery case 32 toward the vehicle, or they may protrude downward from the bottom wall 34 of the battery case 32 toward the vehicle.

[0050] For example, as shown in Figure 5, if the ribs 72 and 74 protrude upward from the bottom wall 34 of the battery case 32 toward the vehicle, the ribs 72 and 74 will be located inside the battery case 32. Therefore, the ribs 72 and 74 will be located together with the rib 46 between the pair of side walls 40 and 42 of the battery case 32. This makes it possible to further improve the rigidity of the battery case 32 itself.

[0051] On the other hand, in this embodiment, as shown in Figure 3, the ribs 56 and 58 protrude from the bottom wall 34 of the battery case 32 toward the lower side of the vehicle. In this case, the ribs 56 and 58 are provided on the outside of the battery case 32. In this embodiment, as shown in Figure 4, the ribs 56 and 58 are set to overlap with the rockers 16 and 18 in a side view of the vehicle, thereby enabling the ribs 56 and 58 to transmit loads input along the vehicle width direction to the opposite side along the vehicle width direction.

[0052] In this embodiment, as shown in Figure 3, the ribs 56 and 58 protrude from the bottom wall 34 of the battery case 32 toward the lower side of the vehicle. Compared to the case where ribs 72 and 74 (see Figure 5) are provided within the housing 44 of the battery case 32, the volume within the housing 44 can be increased.

[0053] Therefore, in this embodiment, it is possible to improve the rigidity of the battery case 32 while ensuring battery capacity. However, the present invention also includes a configuration in which the ribs 72 and 74 protrude from the bottom wall 34 of the battery case 32 toward the upper side of the vehicle, as shown in Figure 5.

[0054] In this embodiment, a fastening portion 52 is provided on the cover 48 that closes the housing portion 44 of the battery case 32. This cover 48 constitutes the floor. As a result, in this embodiment, for example, compared to a case where a separate floor panel is provided above the cover 48 (not shown in the figures as a comparative example), the number of parts can be reduced and the amount of work required can be reduced.

[0055] <Note> Furthermore, the following configurations may be combined as appropriate to form the battery pack structure according to the present invention.

[0056] (Composition 1) The battery pack structure comprises a battery pack body in which battery cells are housed in a state where they extend along the vehicle width direction and are arranged along the vehicle longitudinal direction; a first rib in the bottom wall which constitutes a part of the battery pack body, which protrudes along the vehicle width direction between the battery cells arranged along the vehicle longitudinal direction and constitutes another part of the battery pack body and is spanned between a pair of side walls which extend along the vehicle longitudinal direction at both ends in the vehicle width direction; and a fastening portion provided on the outside of the side wall of the battery pack body, which is positioned on the extension of the first rib in the vehicle width direction in a vehicle plan view, constitutes a part of the vehicle frame and is fastened to a rocker which extends along the vehicle longitudinal direction at both outer ends in the vehicle width direction.

[0057] (Configuration 2) The battery pack body is further provided with a second rib on its bottom wall, which transmits a load applied along the vehicle width direction to the opposite side in the vehicle width direction along the vehicle width direction.

[0058] (Composition 3) The second rib protrudes downward from the bottom wall of the battery pack body in the vertical direction of the vehicle and is set to overlap with the rocker when viewed from the side of the vehicle.

[0059] (Composition 4) The fastening portion is provided on the cover that closes the housing portion of the battery pack body, and the cover constitutes the floor portion of the vehicle interior.

[0060] Furthermore, the present invention can be implemented with various modifications without departing from its spirit. Of course, the scope of the present invention is not limited to the embodiments described above. [Explanation of Symbols]

[0061] 10. Battery pack structure 12 vehicles 16 Rocka 18 Rocca 28 battery cells 30 Battery Pack (Battery Pack Unit) 32 Battery Case (Battery Pack Body) 34 Bottom wall 40 side wall 42 Side wall 44 containment section 46 Ribs (1st Rib) 48 Cover 52 Fastening part 56 Ribs (2nd Rib) 58 Rib (2nd Rib) 72 Ribs (2nd Rib) 74 Ribs (2nd Rib)

Claims

1. A battery pack body formed in the shape of a box with an opening on the upper side of the vehicle, and which houses battery cells that extend along the width direction of the vehicle and are arranged along the front-rear direction of the vehicle, A cover is positioned on the vehicle's upper side of the opening of the battery pack body, forming part of the floor inside the vehicle and covering the housing of the battery pack body. In the bottom wall which constitutes a part of the battery pack body, a first rib is provided which protrudes in the vehicle width direction between the battery cells arranged in the vehicle longitudinal direction and spans between a pair of side walls which constitute another part of the battery pack body and extend in the vehicle longitudinal direction at both ends in the vehicle width direction, A fastening portion is provided on the cover and on the outside of the side wall of the battery pack body, positioned on the extension of the first rib in the vehicle width direction in a plan view of the vehicle, constituting a part of the vehicle frame, and fastened to a rocker that extends along the vehicle longitudinal direction on both outer sides in the vehicle width direction, A battery pack structure equipped with this feature.

2. The battery pack structure according to claim 1, further comprising a second rib provided on the bottom wall of the battery pack body for transmitting a load input along the vehicle width direction to the opposite side in the vehicle width direction along the vehicle width direction.

3. The battery pack structure according to claim 2, wherein the second rib protrudes downward from the bottom wall of the battery pack body in the vertical direction of the vehicle and is set to overlap with the rocker when viewed from the side of the vehicle.

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