Vehicle battery packs

Abstract

To provide a technology which achieves reduction of a load input to a battery pack without relying only on an EA material.SOLUTION: A vehicle battery pack 2 is provided. The battery pack 2 includes a lower case 12 and an upper case 14 which house a battery module 4. The battery pack 2 further includes: an inner bracket 20 which is fixed to the inner side of a side wall part 16 so as to face an inner surface of the side wall part 16 at the outer side as seen in a vehicle width direction of the lower case 12 and be spaced apart from the inner surface; and an outer bracket 30 fixed to the outer side of the side wall part 16 so as to face an outer surface of the side wall part 15 and be spaced apart from the outer surface. The structure improves bending rigidity at the outer side as seen in the vehicle width direction of the battery pack 2 to reduce a load input effectively.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a battery pack. [Background technology]

[0002] Energy absorbing materials (hereinafter simply referred to as EA materials) are arranged on the left and right sides of the battery pack, which is placed under the floor of the vehicle, to absorb external energy from the sides. For example, the EA materials are connected to flanges that protrude from the bottom of the lower case of the battery pack to the left and right sides of the vehicle (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-6303 Summary of the Invention [Problem to be solved by the invention]

[0004] In such structures, one way to reduce the load input to the battery pack in response to safety and other requirements is to increase the size of the EA material, which may lead to an increase in the size of the battery pack mounting structure.

[0005] This specification provides a technology that achieves a reduction in load input to a battery pack without relying solely on EA materials. [Means for solving the problem]

[0006] The technology disclosed in this specification is embodied in a battery pack for a vehicle. The battery pack includes a lower case and an upper case that house battery modules. The battery pack also includes an inner bracket fixed to the inside of a side wall portion of the lower case that is on the outer side of the vehicle width direction, facing and spaced apart from the inner surface of the side wall, and an outer bracket fixed to the outside of the side wall, facing and spaced from the outer surface of the side wall.

[0007] This battery pack can improve the bending rigidity of the side wall portions on both the inside and outside of the side wall portions of the lower case, thereby suppressing or avoiding an increase in the size of the battery pack mounting structure and reducing the load input to the battery pack. [Brief explanation of the drawings]

[0008] [Figure 1] 1A is a front view of a battery pack according to an embodiment of the present invention; FIG. 1B is a plan view of the battery pack according to the embodiment of the present invention; [Figure 2] 2 is a cross-sectional view taken along line II-II in FIG. 1, excluding the upper case, showing the EA material in imaginary lines. [Figure 3] 3 is a cross-sectional view taken along line III-III in FIG. 1, showing a portion excluding an upper case, with the EA material shown in imaginary lines. [Figure 4] 1 is a side view of the outer bracket as seen from the outside in the vehicle width direction, with the EA member shown in phantom lines. DETAILED DESCRIPTION OF THE INVENTION

[0009] The embodiment disclosed in this specification comprises a lower case and an upper case that house a battery module, an inner bracket fixed to the inside of the side wall portion on the outer side of the lower case in the vehicle width direction so as to face the inner surface of the side wall portion at a distance from the inner surface, and an outer bracket fixed to the outside of the side wall portion so as to face the outer surface of the side wall portion at a distance from the outer surface of the side wall portion.

[0010] In one embodiment of the present disclosure, the inner bracket and the outer bracket may have an elongated shape extending in the front-to-rear direction of the vehicle along the side wall portion, thereby improving the bending rigidity of the battery pack in a predetermined range along the side wall portion and effectively reducing the load input.

[0011] In one embodiment of the present disclosure, the lower case may include, at least in a portion along the vehicle fore-and-aft direction, an inner closed space defined between the side wall portion and the inner bracket, and an outer closed space defined between the side wall portion and the outer bracket, on the outer side in the vehicle width direction. In the portion including the inner closed space and the outer closed space, the bending rigidity of the side wall portion can be further increased, and the load input can be further reduced.

[0012] In one embodiment of the present disclosure, the outer bracket may include a base portion that abuts against the outside of the bottom of the lower case, an outer wall portion that faces the side wall portion, and an outer flange portion that extends from an upper edge of the outer wall portion toward the outside in the vehicle width direction. Furthermore, the outer flange portion may include a fixing portion for fixing the EA material along the outer surface of the outer wall portion. This fixable configuration of the EA material allows the EA material to reduce impact on the battery pack. The EA material is also firmly held by the outer bracket.

[0013] In one embodiment of the present disclosure, the outer flange portion of the outer bracket may have a corrugated shape that rises and falls in the vehicle up-and-down direction along the vehicle longitudinal direction, thereby further increasing the bending rigidity of the outer bracket and further reducing the load input from the outside in the vehicle width direction.

[0014] In one embodiment of the present disclosure, the lowest portion of the corrugated shape of the outer flange portion of the outer bracket may include a fixing portion for the EA material, which makes it possible to easily fix the EA material while improving the bending rigidity of the outer bracket.

[0015] Hereinafter, embodiments of the vehicle battery pack disclosed in this specification will be described with reference to the accompanying drawings. In this specification, the terms "front," "rear," and "front-rear direction" refer to the front, rear, and front-rear directions of the vehicle, respectively. Similarly, the terms "left," "right," and "width direction" refer to the left, right, and width directions of the vehicle, respectively, and the terms "upper," "lower," and "height direction" refer to the upper, lower, and height directions of the vehicle, respectively.

[0016] In the drawings, the direction FR indicates the front in the longitudinal direction of the vehicle, the direction RR indicates the rear in the longitudinal direction of the vehicle, the direction LH indicates the left in the width direction of the vehicle, the direction RH indicates the right in the width direction of the vehicle, the direction UP indicates the upward direction in the vertical direction of the vehicle, and the direction DW indicates the downward direction in the vertical direction of the vehicle.

[0017] In this specification, the term "vehicle" refers to a so-called electric vehicle, and may include a hybrid vehicle, a fuel cell vehicle, and a solar car. A vehicle is typically an automobile.

[0018] 1, the battery pack 2 includes a battery module 4 and a case 10 that houses the battery module 4. The battery module 4 is a modularized version of many lithium-ion secondary battery cells. The battery pack 2 houses, for example, four of these battery modules 4 aligned in a row.

[0019] The case 10 includes a lower case 12 and an upper case 14. The lower case 12 is formed with a downward recess so as to be able to accommodate the lower side of the battery module 4. The upper case 14 covers the upper side of the battery module 4 and is sealed to the lower case 12 to accommodate the battery module 4. The case 10 is made of high-strength steel plate or a composite material in which at least the frame portion is made of high-strength steel plate and the rest is made of FRGP. The battery pack 2 is arranged, for example, below a floor panel that is placed under the passenger compartment of the vehicle.

[0020] 1, an inner bracket 20 and an outer bracket 30 are provided on both outer sides of the battery pack 2 in the vehicle width direction. The inner bracket 20 and the outer bracket 30 are formed as elongated members made of metal, for example.

[0021] Fig. 2 shows a cross-sectional view of the battery pack 2 taken along line II-II in Fig. 1. The cross-sectional view taken along line II-II shows an example of the vicinity of the side wall portion 16 located on the outer side (left side) of the battery module 4 in the vehicle width direction. Note that Fig. 2 only shows the side wall portion 16 on the left side of the vehicle, but the right side of the vehicle also has a similar structure. In Fig. 2, the EA material is shown by a virtual line.

[0022] 2, the inner bracket 20 extends in the vehicle front-rear direction along the inner surface of the side wall portion 16 of the lower case 12 in the vehicle width direction. The inner bracket 20 is fixed to be spaced apart from and facing the inner surface of the side wall portion 16. The inner bracket 20 includes a base portion 22 fixed to the inner bottom portion of the lower case 12, an inner wall portion 24 rising from the base portion 22, and an inner flange portion 26 fixed to the upper surface of the flange portion 12a of the lower case 12.

[0023] As shown in FIG. 2 , the base 22 of the inner bracket 20 is fixed along the left edge of the inside bottom of the lower case 12. There are no particular limitations on the fixing method, but for example, if the fixed portion is a steel plate or the like, it may be fixed by welding or the like. An inner wall portion 24 rising from the base 22 extends upward at a distance from the inner surface of the side wall portion 16. The upper edge of the inner wall portion 24 reaches the height of the flange portion 12a of the lower case 12. An inner flange portion 26 extends from the inner wall portion 25 toward the outside (left side) in the vehicle width direction and is fixed to the upper surface of the flange portion 12a of the lower case 12. There are no particular limitations on the fixing method, but for example, if the fixed portion is a steel plate or the like, it may be fixed by welding or the like.

[0024] 2, a closed space 28 is formed between the side wall portion 16 of the lower case 12 and the inner bracket 20. The closed space 28 is surrounded by the outer surface 24a of the inner wall portion 24 of the inner bracket 20, the lower surface 26a of the inner flange portion 26, and the inner surface 16a of the side wall portion 16 of the lower case 12. In the battery pack 2, the closed space generally extends between the inner bracket 20 and the side wall portion 16 in the vehicle fore-and-aft direction over the range of the side wall portion 16 where the battery module 4 is arranged. The closed space 28 is an example of an inner closed space disclosed in this specification.

[0025] 2, the outer bracket 30 extends in the vehicle front-rear direction along the outer surface 16b of the side wall portion 16 of the lower case 12 in the vehicle width direction. The outer bracket 30 is fixed so as to be spaced apart from and face the outer surface 16b of the side wall portion 16. The outer bracket 30 includes a base portion 32 fixed to the outside of the bottom of the lower case 12, an outer wall portion 34 rising from the base portion 32, and an outer flange portion 36 fixed to the underside of the flange portion 12a of the lower case 12.

[0026] As shown in FIG. 2 , the base 32 of the outer bracket 30 is fixed along the left edge of the outside bottom of the lower case 12. The fixing method is not particularly limited, but it may be fixed by welding or the like, for example. An outer wall portion 34 rising from the base 32 extends upward at a distance from the outer surface 16b of the side wall portion 16. The upper edge of the outer wall portion 34 reaches a height H1 corresponding to the height of the lower surface of the flange portion 12a of the lower case 12. The outer flange portion 36 extends from the outer wall portion 34 outward in the vehicle width direction (left side) and is fixed to the lower surface of the flange portion 12a of the lower case 12. The fixing method is not particularly limited, but it may be fixed by welding or the like, for example.

[0027] As shown in Fig. 2, a closed space 38 is formed outside the side wall portion 16 of the lower case 12. The closed space 38 is surrounded by the inner surface 34a of the outer wall portion 34 of the outer bracket 30, the lower surface of the flange portion 12a, and the outer surface 16b of the side wall portion 16 of the lower case 12. The closed space 38 is formed to have a smaller width in the vehicle width direction than the closed space 28. In the battery pack 2, the closed space extends generally between the outer bracket 30 and the side wall portion 16 in the vehicle fore-and-aft direction within the range of the side wall portion 16 where the battery module 4 is arranged. The closed space 38 is an example of an outer closed space disclosed in this specification.

[0028] Fig. 3 shows a cross-sectional view of the battery module 4 taken along line III-III in Fig. 1. Like the cross-sectional view taken along line II-II, the cross-sectional view taken along line III-III shows an example of the vicinity of the side wall portion 16. Fig. 3 corresponds to the location where the outer bracket 30 has a fixing portion 39 for fixing the EA material 50. Although Fig. 3 also shows only the side wall portion 16 on the left side of the vehicle, the right side of the vehicle also has a similar structure. In Fig. 3, the EA material is shown by a virtual line.

[0029] 3, the base 32 of the outer bracket 30 is fixed along the left edge of the outside bottom of the lower case 12, as described above. An outer wall 35 rises from the base 32 and extends upward at a distance from the outer surface 16b of the side wall 16. The outer wall 35 reaches a height H2 that corresponds to the fixing height of the EA material 50 to be fixed thereto.

[0030] The outer flange portion 37 extends from the outer wall portion 35 to the outer side (left side) in the vehicle width direction at a height H2 that abuts or is close to the upper surface of the EA material 50 to be fixed. The outer flange portion 37 has a fixing portion 39 for fixing the EA material 50 to the outer flange portion 37 and integrating it with the battery pack 2. The fixing portion 39 is configured so that the end of the EA material 50 on the battery pack 2 side can be brought close to the outer wall portion 35 and fixed below the outer flange portion 37. The method for fixing the EA material 50 is not particularly limited, and may be, for example, a through-hole that can fix the EA material 50 with a bolt. The EA material 50 is fixed at the fixing portion 39 to a battery pack holding element 60, such as a lower panel or a cross member, that is arranged below the battery pack 2.

[0031] 2 and 3, the outer bracket 30 has an outer flange portion 36 with a height H1 that reaches the upper surface of the flange portion 12a of the lower case 12 at a location that does not have a fixing portion 39 of the EA material 50. Furthermore, the outer bracket 30 has an outer flange portion 37 with a height H2 that reaches the upper surface of the EA material 50, which is lower than the height of the flange portion 12a of the lower case 12, at a location that has a fixing portion 39 of the EA material 50.

[0032] 4, the outer bracket 30 has a corrugated shape whose height changes vertically along the vehicle longitudinal direction as needed near the fixing portion of the EA material 50. The highest point of the corrugated shape corresponds to the outer flange portion 36, and the lowest point corresponds to the outer flange portion 37.

[0033] As shown in FIG. 3, no closed space 38 is formed outside the side wall portion 16 at the location where the fixing portion 39 for fixing the EA material 50 of the outer bracket 30 is provided.

[0034] The EA material 50 is a hollow member that extends with a constant cross section along the longitudinal direction of the vehicle. The EA material 50 is provided symmetrically with respect to one another in the vehicle width direction. When a side collision occurs to the vehicle, the EA material 50 absorbs collision energy by compressive deformation. The EA material 50 is made of a metal such as aluminum, for example, but is not limited to, a material.

[0035] Next, we will explain the operation of the battery pack 2. By providing the inner bracket 20 and the outer bracket 30, the battery pack 2 can provide a closed space 28 inside the side wall portion 16 of the lower case 12 and a closed space 38 outside the side wall portion 16. Furthermore, even though there is no closed space 38 at the location where the fixing portion 39 of the EA material 50 is located, the EA material 50 is fixed by the outer wall portion 35 and outer flange portion 37 of the outer bracket 30. Furthermore, the outer flange portions 36, 37 of the outer bracket 30 have a corrugated shape.

[0036] As a result, the battery pack 2 has high bending rigidity on the outer side in the vehicle width direction, and is excellent at reducing the load input to the battery pack 2 from the outer side in the vehicle width direction.

[0037] Furthermore, the battery pack 2 itself can have excellent bending rigidity against external forces from the vehicle width direction. That is, the battery pack 2 itself can provide improved load input reduction capability. This reduces or eliminates reliance on the EA material 50 for reducing load input during a side collision. Furthermore, the degree of freedom in using the EA material 50, such as whether or not to attach the EA material 50 and the size of the EA material 50, is improved.

[0038] Furthermore, according to the above-described embodiment, the inner bracket 20 and the outer bracket 30 are fixed to the lower case 12 by welding. Therefore, the closed spaces 28, 38 are firmly maintained, and the intended load input reduction capability can be achieved.

[0039] In the above embodiment, the battery pack 2 is provided with the EA material 50 at the outer flange portion 37, but this is not limited to this. The EA material 50 may be provided in a state in which the closed space 38 is provided. In addition, the battery pack 2 is provided with the EA material 50, but this is not limited to this. If the EA material 50 is not provided, the closed spaces 28, 38 may be provided on the inside and outside of the side wall portion 16, respectively, over the entire vehicle in the longitudinal direction.

[0040] In the above embodiment, the battery pack 2 is provided with the closed space 38 that is smaller than the closed space 28, but this is not limited to this. The width of the closed spaces 28, 38 in the vehicle width direction can be set as appropriate.

[0041] This specification may include the following configurations. [1] A battery pack for a vehicle, The battery pack includes a lower case and an upper case that house the battery module, a battery pack including: an inner bracket fixed to the inside of a side wall portion on the outer side of the lower case in the vehicle width direction so as to face the inner surface of the side wall portion at a distance from the inner surface of the side wall portion; and an outer bracket fixed to the outside of the side wall portion so as to face the outer surface of the side wall portion at a distance from the outer surface of the side wall portion. [2] The battery pack according to [1], wherein the inner bracket and the outer bracket have an elongated shape extending in the fore-and-aft direction of the vehicle along the side wall portion. [3] The battery pack described in [1] or [2], wherein the lower case has, at least in a portion along the vehicle fore-and-aft direction, an inner closed space defined between the side wall portion and the inner bracket, and an outer closed space defined between the side wall portion and the outer bracket, on the outer side in the vehicle width direction. [4] The outer bracket includes a base portion that abuts against the outer side of the bottom of the lower case, an outer wall portion that faces the side wall portion, and an outer flange portion that extends outward in the vehicle width direction from an upper end edge of the outer wall portion, The battery pack according to any one of [1] to [3], wherein the outer flange portion includes a fixing portion for fixing an energy absorbing material along the outer surface of the outer wall portion. [5] The battery pack according to [4], wherein the outer flange portion of the outer bracket has a corrugated shape that extends up and down in the vehicle vertical direction along the vehicle longitudinal direction. [6] The battery pack according to [5], wherein the lowest portion of the corrugated shape includes the fixing portion.

[0042] Although several specific examples have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility either alone or in combination. [Explanation of symbols]

[0043] 2: battery pack, 4: battery module, 10: case, 12: lower case, 14: upper case, 16: side wall, 20: inner bracket, 22: base, 24: inner wall, 26: inner flange, 28: closed space, 30: outer bracket, 32: base, 34: outer wall, 36: outer flange, 38: closed space, 50: EA material (energy absorbing material), 60: battery pack fixing element

Claims

1. A battery pack for a vehicle, The battery pack includes a lower case and an upper case that house the battery module, an inner bracket fixed to an inner side of a side wall portion on an outer side in a vehicle width direction of the lower case so as to face the inner surface of the side wall portion at a distance from the inner surface of the side wall portion; and an outer bracket fixed to an outer side of the side wall portion so as to face the outer surface of the side wall portion at a distance from the outer surface of the side wall portion, the inner bracket and the outer bracket have an elongated shape extending in the vehicle front-rear direction along the side wall portion, the lower case includes, at least in a portion along a vehicle longitudinal direction, an inner closed space defined between the side wall portion and the inner bracket, and an outer closed space defined between the side wall portion and the outer bracket, on an outer side in a vehicle width direction; the outer bracket includes a base portion that abuts against an outer side of a bottom portion of the lower case, an outer wall portion that faces the side wall portion, and an outer flange portion that extends outward in a vehicle width direction from an upper end edge of the outer wall portion, The outer flange portion includes a fixing portion for fixing an energy absorbing material along an outer surface of the outer wall portion.

2. The battery pack according to claim 1 , wherein the outer flange portion of the outer bracket has a corrugated shape that extends up and down in the vehicle vertical direction along the vehicle longitudinal direction.

3. The battery pack according to claim 2 , wherein the lowest portion of the corrugated shape includes the fixing portion.

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