Battery pack

Abstract

To provide a battery pack configured such that gas or the like generated from the battery pack displaces an end portion of a bottom wall portion of an upper case upward relative to a central portion of the bottom wall portion of the upper case.SOLUTION: A battery pack 1 which houses a battery stack 20 including a plurality of stacked battery cells includes a lower case 30 and an upper case 10. The upper case 10 includes a bottom wall portion 10a and a side wall portion 10b. The end portion of the bottom wall portion 10a or the side wall portion 10b includes an excess portion 10e. The excess portion 10e is stretched and configured such that gas generated inside the battery pack causes the end portion of the bottom wall portion near the connection portion between the bottom wall portion and the side wall portion to be displaced upward.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a battery pack.

Background Art

[0002] Electric vehicles such as electric cars and hybrid cars are equipped with a battery pack.

[0003] Patent Document 1 discloses a battery pack provided with a pressure release portion in a portion of an upper case having higher rigidity than other portions.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] For improving the mounting efficiency, the battery pack is required to be miniaturized. Therefore, the surplus space between the upper case and the battery pack is also limited. High-temperature gas or debris ejected from the cells of the battery pack locally diffuses into a certain area within this surplus space, locally lifting the upper case. This may cause a short circuit between high-voltage components located above the locally lifted upper case.

Means for Solving the Problems

[0006] A battery pack according to an aspect of the present disclosure is a battery pack that houses a battery stack including a plurality of stacked battery cells, and the battery pack includes a lower case and an upper case. The upper case includes a bottom wall portion and a side wall portion, and an end portion of the bottom wall portion or the side wall portion includes an extra-length portion.

[0007] In the above battery pack, the excess length portion may be configured to be stretched or slid by gas generated from the battery pack so as to displace upward an end portion of the bottom wall portion that is a connection portion between the bottom wall portion and the side wall portion.

[0008] In the above battery pack, the excess length portion may include at least one of portions having an S shape, a U shape, a V shape, and a W shape.

[0009] In the above battery pack, the excess length portion may be a first portion joined to the side wall portion, and may include a first portion made of a material having a higher elongation rate than the elongation rate of the material of the side wall portion or having a thinner plate thickness than the plate thickness of the side wall portion.

[0010] In the above battery pack, the excess length portion includes a first side wall portion connected to the bottom wall portion and a second side wall portion separate from the bottom wall portion, the first side wall portion and the second side wall portion are configured to be slidable, and a seal portion may be provided between the first side wall portion and the second side wall portion.

Advantages of the Invention

[0011] According to the present disclosure, it is possible to provide a battery pack configured such that an end portion of the bottom wall portion of the upper case is displaced upward with respect to a central portion of the bottom wall portion of the upper case by gas or the like generated from the battery pack.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0013] Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. Also, for clarity of explanation, the following description and drawings are appropriately simplified.

[0014] FIG. 1 is a cross-sectional view for explaining a vehicle underbody 100 and a battery pack 1 according to some embodiments of the present disclosure. The battery pack 1 is disposed under the underbody 100 that constitutes the lower surface of the vehicle body. The battery pack 1 houses a battery stack 20 including a plurality of stacked battery cells. The battery pack 1 includes the battery stack 20, a lower case 30, and an upper case 10. The battery stack 20 is covered by the lower case 30 and the upper case 10. The battery stack 20 includes a plurality of stacked battery cells. The battery cells are secondary batteries such as, for example, nickel-metal hydride batteries or lithium-ion batteries. The battery cells may include an inorganic solid electrolyte.

[0015] The lower case 30 has a box shape with an opening at the top, and has a bottom wall portion 30a, a side wall portion 30b, and a flange portion 30c. The upper case 10 has a box shape with an opening at the top, and has a bottom wall portion 10a, a side wall portion 10b, and a flange portion 10c. The flange portion 30c of the lower case 30 and the flange portion 10c of the upper case 10 are joined by clamping a sealing member such as a packing between them and fastening the mating surfaces of each other along the circumferential direction with a plurality of bolts or the like.

[0016] The underbody 100 includes a floor bead portion 110 protruding upward and a floor tunnel portion 120 extending in the vehicle front-rear direction at the vehicle width center. High-voltage components 121, cables, etc. are arranged inside the floor tunnel portion 120. That is, the high-voltage components 121 and the like are arranged above the central portion of the bottom wall portion 10a of the upper case 10 of the battery pack 1.

[0017] The upper case 10 has a surplus length portion (details will be described later), which is one of the characteristic portions of the present disclosure, at both ends of the bottom wall portion 10a or the side wall portion 10b. The surplus length portion is formed by being bent in various shapes and is configured to be extended or slid by the gas generated from the battery pack. Examples of the shape of the surplus length portion can be an S shape, a U shape, a V shape, a W shape, and combinations thereof. In this specification, the end portion of the bottom wall portion 10a of the upper case 10 can refer to both side portions (i.e., excluding the central portion) when the bottom wall portion 10a is trisected from the connection portion between the bottom wall portion 10a and the side wall portion 10b. More preferably, the end portion of the bottom wall portion of the upper case 10 can refer to both side portions (excluding the central portion) when the bottom wall portion is divided into five equal parts from the connection portion between the bottom wall portion and the side wall portion. As shown by the circular VI in FIG. 1, the surplus length portion at the right end will be described in detail.

[0018] FIG. 2 is a cross-sectional view for explaining an example of the surplus length portion of the upper case shown by the circular VI in FIG. 1. The surplus portion 10e of the upper case 10 is bent in an S shape when viewed from the paper surface direction (vehicle longitudinal direction) at the right end portion of the bottom wall portion 10a. Due to the gas generated from the battery pack inside the upper case 10, the bottom wall portion 10a of the upper case 10 is lifted upward, and the surplus portion 10e is extended. The upper case is configured to displace the end portion of the bottom wall portion upward with respect to the central portion of the bottom wall portion 10a. Thereby, not only the central portion but also the end portion of the bottom wall portion of the upper case 10 rises substantially horizontally. Therefore, even if the surplus space between the upper case and the battery pack is limited, the gas generated from the battery pack can diffuse over the entire surplus space, and as a result, a short circuit between high-voltage components can be prevented.

[0019] FIG. 3 is a diagram for explaining various modification examples of the surplus portion of the bottom wall portion of the upper case. The modification examples shown in FIG. 3 show various surplus portions formed at the right end portion of the bottom wall portion 10a of the upper case 10. The upper diagram of FIG. 3 shows an example in which the surplus portion 10e of the upper case 10 is bent in an S shape when viewed from the paper surface direction (vehicle longitudinal direction) at the right end portion of the bottom wall portion 10a of the upper case 10. The number of S shapes is not limited to this.

[0020] The middle diagram of FIG. 3 shows an example in which the surplus portion 10e of the upper case 10 is bent in a W shape or a V shape when viewed from the paper surface direction (vehicle longitudinal direction) at the right end portion of the bottom wall portion 10a. The number of W shapes or V shapes is not limited to this.

[0021] The lower diagram of FIG. 3 shows an example in which the surplus portion 10e of the upper case 10 is bent in a U shape when viewed from the paper surface direction (vehicle longitudinal direction) at the right end portion of the bottom wall portion 10a. The number of U shapes is not limited to this.

[0022] The upper case 10 of these modified examples can be configured such that the extra-length portion 10e at the end of the bottom wall portion 10a is extended by gas or the like generated from the battery cell, and the end of the bottom wall portion 10a is displaced upward with respect to the central portion of the bottom wall portion 10a. Therefore, the bottom wall portion 10a of the upper case 10 rises substantially horizontally not only at the central portion but also at the end portions.

[0023] FIG. 4 is a cross-sectional view for explaining various other modified examples of the extra-length portion of the side wall portion of the upper case. The left diagram of FIG. 4 shows the smoothly bent extra-length portion 10e formed in the side wall portion 10b. The number of smoothly bent portions is not limited to this. The right diagram of FIG. 4 shows the serrated stepwise bent extra-length portion 10e formed in the side wall portion 10b. The number of serrated stepwise bent portions is not limited to this.

[0024] The upper case 10 of these modified examples can be configured such that the extra-length portion 10e of the side wall portion is extended by gas or the like generated from the battery cell, and the end of the bottom wall portion 10a is displaced upward with respect to the central portion of the bottom wall portion 10a. Therefore, the bottom wall portion 10a of the upper case 10 rises substantially horizontally not only at the central portion but also at the end portions.

[0025] FIG. 5 is a cross-sectional view for explaining various other modified examples of the extra-length portion of the side wall portion of the upper case. The left diagram of FIG. 5 shows the first portion (extra-length portion 10e) joined to the side wall portion 10b. This first portion includes a material having a higher elongation rate than the elongation rate of the material of the side wall portion 10b. Or, in another modified example, this first portion (extra-length portion 10e) has a smaller plate thickness than the plate thickness of the side wall portion 10b. Thereby, due to gas or the like generated from the battery pack in the upper case, this first portion is locally extended.

[0026] Also, the right diagram in FIG. 5 includes a first side wall portion 10b connected to the bottom wall portion 10a and a second side wall portion (extra length portion 10e) separate from the bottom wall portion 10a. The second side wall portion (extra length portion 10e) has a cylindrical structure for slidably inserting the first side wall portion 10b connected to the bottom wall portion 10a through a sealing portion. The sealing portion can be a sealing sponge, a rubber gasket, or the like. In the right diagram of FIG. 5, a cylindrical structure is provided in the second side wall portion (extra length portion 10e), but a cylindrical structure may also be provided in the first side wall portion 10b.

[0027] In these modified examples, the upper case 10 can be configured such that the extra length portion 10e of the side wall portion is extended or slid by gas or the like generated from the battery cell, and the end portion of the bottom wall portion 10a is displaced upward with respect to the central portion of the bottom wall portion 10a. Therefore, the bottom wall portion 10a of the upper case 10 rises substantially horizontally not only at the central portion but also at the end portion.

[0028] FIG. 6 is a cross-sectional view for explaining the effect depending on the presence or absence of the extra length portion of the upper case during smoking. When gas 25 or debris is generated from the battery stack 20, the bottom wall portion 100a (without extra length portion) of the upper case 10 is lifted upward. The upper diagram in FIG. 6 shows the case where there is no extra length portion in the upper case. The central portion of the bottom wall portion 100a of the upper case 10 is lifted above the end portion of the bottom wall portion 10a and reaches the floor tunnel portion 120 above this central portion. As a result, there is a risk that high-voltage components inside the floor tunnel portion 120 may be short-circuited.

[0029] The lower diagram in FIG. 6 shows the case where there is an extra length portion in the upper case. When gas 25 or debris is generated from the battery stack 20, the bottom wall portion 10a (with extra length portion) of the upper case 10 displaces the end portion of the bottom wall portion 10a upward with respect to the central portion of the bottom wall portion 10a. Therefore, the bottom wall portion 10a of the upper case 10 rises substantially horizontally not only at the central portion but also at the end portion. As a result, even if the surplus space between the upper case and the battery pack is limited, gas or the like generated from the battery pack can diffuse over the entire surplus space, and as a result, a short circuit between high-voltage components can be prevented.

[0030] Note that the present invention is not limited to the above-described embodiments, and can be appropriately modified without departing from the gist thereof.

Description of Reference Numerals

[0031] 1 Battery pack 10 Upper case 10a Bottom wall portion 10b Side wall portion 11 Seal 20 Battery stack 25 Gas 30 Lower case 100 Underbody 110 Floor bead portion 120 Floor tunnel portion 121 High-voltage component 130 General floor portion

Claims

1. A battery pack that houses a battery stack including a plurality of stacked battery cells, wherein the battery pack includes a lower case and an upper case, the upper case includes a bottom wall portion and side wall portions, and an end portion of the bottom wall portion or the side wall portion includes an extra length portion, the battery pack.

2. The battery pack according to claim 1, wherein the extra length portion is configured to be extended or slid by gas generated from the battery pack to displace upward an end portion of the bottom wall portion that is a connection portion between the bottom wall portion and the side wall portions.

3. The battery pack according to claim 1 or 2, wherein the extra length portion includes at least one of portions having an S shape, a U shape, a V shape, and a W shape.

4. The battery pack according to claim 1 or 2, wherein the extra length portion includes a first portion joined to the side wall portion, and the first portion is made of a material having a higher elongation rate than the elongation rate of the material of the side wall portion or has a thickness thinner than the plate thickness of the side wall portion.

5. The extra length portion includes a first side wall portion connected to the bottom wall portion and a second side wall portion separate from the bottom wall portion, the first side wall portion and the second side wall portion are configured to be slidable, and a seal portion is provided between the first side wall portion and the second side wall portion, the battery pack according to claim 1 or 2.

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