Battery pack

Abstract

To provide a battery pack capable of discharging gas blown out from a battery cell to the outside of a case with a simple structure.SOLUTION: A battery pack in which multiple battery cells are housed in a case where a gas exhaust port is provided for discharging gas blown out from the battery cells includes a lid member that closes the gas exhaust port, a first adhesive that bonds the lid member to the case on the upstream side of the gas exhaust port in a preset gas exhaust direction, a second adhesive having a melting point lower than that of the first adhesive and bonding the lid member to the case such that the case is watertight, and an opening control bar that is provided across the gas exhaust port and is connected to the case at two points.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a battery pack in which a plurality of battery cells are housed in a case. On the upper surface of such a case, a pressure release portion is provided where a predetermined region opens due to an increase in internal pressure. The pressure release portion is composed of an opening formed in the case and a lid member that closes the opening. The lid member has one end portion in one direction fixed to the case by a fastening member such as a tapping screw at the outer peripheral portion of the opening, and the other end portion is removably held by the case. According to such a battery pack, when gas generated from the battery cell due to an internal short circuit or the like fills the case and the internal pressure rises, the lid member in the region facing the opening is deformed as the pressure rises, and the other end portion of the lid member held removably comes off, the opening formed in the case opens, and the gas in the case can be discharged to the outside of the case.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a battery pack mounted under the floor of an electric vehicle, since the case needs to be waterproof, it is necessary for the lid member to seal the outer peripheral portion of the opening formed in the case. Therefore, a seal member such as a rubber packing is installed between the outer peripheral portion of the opening and the lid member, and it is impossible to discharge the gas blown out from the battery cell to the outside of the case with a simple structure.

[0005] In view of the above circumstances, at least one embodiment of the present invention aims to provide a battery pack that can discharge gas blown out from a battery cell to the outside of the case with a simple structure. [Means for solving the problem]

[0006] (1) A battery pack according to at least one embodiment of the present invention is a battery pack in which a plurality of battery cells are housed in a case, wherein the case is provided with a gas outlet for discharging gas blown out from the battery cells, and the battery pack comprises a lid member that closes the gas outlet, a first adhesive that adheres the lid member to the case on the upstream side of the gas discharge direction of a predetermined gas, a second adhesive having a lower melting point than the first adhesive that adheres the lid member to the case so that the case is watertight, and an opening control bar that straddles the gas outlet and is connected to the case at two points.

[0007] According to the configuration described in (1) above, the gas blown out from the battery cell melts the second adhesive, causing the lid member to open to the extent that it interferes with the opening control bar, with the first adhesive acting as a pivot point. Thus, the gas blown out from the battery cell can be discharged to the outside of the case with a simple structure.

[0008] (2) In some embodiments, in the configuration of (1) above, the lid member has a groove provided along a predetermined gas discharge direction of the gas outlet.

[0009] According to the configuration in (2) above, the gas discharged from the gas outlet causes the lid member to separate from the case, and a ridge is formed on the lid member along the groove, thereby creating a gas discharge passage. This makes it easier to efficiently discharge the gas blown out from the battery cell.

[0010] (3) In some embodiments, in the configuration of (2) above, the first adhesive adheres the lid member to the case at two locations that are separated from each other.

[0011] According to the configuration described in (3) above, the lid member is more easily deformed between two points that are far apart from each other, making it easier to form a gas discharge passage. This makes it easier to efficiently discharge the gas blown out from the battery cell.

[0012] (4) In some embodiments, in any one of the configurations (1) to (3) above, the gas outlet gradually widens from the upstream side to the downstream side in the discharge direction along a predetermined gas discharge direction of the gas outlet.

[0013] According to the configuration described in (4) above, the cross-sectional area of ​​the gas flow path for the gas ejected from the battery cell is expanded from the upstream side to the downstream side in the gas discharge direction, making it easier to efficiently discharge the gas ejected from the battery cell.

[0014] (5) In some embodiments, in the configuration of (3) above, the opening control bar gradually moves away from the surface of the case toward the center from both side edges perpendicular to the preset gas discharge direction of the gas outlet.

[0015] According to the configuration described in (5) above, the lid member deforms along the opening control bar due to the gas blown out from the battery cell, so that the cross-section of the discharge passage formed by the lid member can be made triangular.

[0016] (6) In some embodiments, in the configuration of (3) above, the opening control bar has a recess into which a ridge formed along the groove as the lid member deforms fits.

[0017] According to the configuration of (6) above, the ridge formed along the groove as the lid member deforms fits into the recess of the opening control bar, thereby restricting the movement of the lid member in a direction intersecting the preset gas discharge direction of the gas outlet. [Effects of the Invention]

[0018] According to at least one embodiment of the present invention, it is possible to discharge the gas blown out from the battery cell to the outside of the case with a simple structure.

Brief Description of the Drawings

[0019] [Figure 1] It is a diagram schematically showing a battery pack according to an embodiment. [Figure 2] It is a diagram schematically showing a main part of the battery pack shown in FIG. 1. [Figure 3] It is a sectional view taken along line III-III of the main part shown in FIG. 2. [Figure 4] It is a diagram showing a state when gas is discharged from the main part of the battery pack shown in FIG. 2. [Figure 5] It is a sectional view taken along line V-V of the main part shown in FIG. 4. [Figure 6] It is a diagram schematically showing a main part of a battery pack according to a modification of Embodiment 1. [Figure 7] It is a diagram schematically showing a main part of a battery pack according to Embodiment 2. [Figure 8] It is a diagram showing a state when gas is discharged from the main part of the battery pack shown in FIG. 7.

Modes for Carrying Out the Invention

[0020] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention thereto, but are merely illustrative examples.

[0021] [Embodiment 1] [Electric Vehicle on which the Battery Pack is Mounted] The electric vehicle equipped with the battery pack according to Embodiment 1 is an electric vehicle (EV) or a hybrid vehicle (HV), and may be a plug-in hybrid vehicle that can be charged externally from an external device (e.g., a fast charger), or a plug-in hybrid vehicle (PHEV) that can supply power externally (e.g., to a general household). The battery pack according to the embodiment is used as a battery pack installed under the floor of the electric vehicle.

[0022] [Overall configuration of the battery pack] Figure 1 is a schematic diagram showing a battery pack 1 according to Embodiment 1. As shown in Figure 1, the battery pack 1 according to the embodiment is a battery pack in which a plurality of battery cells 10 are housed in a case 12. Each of the plurality of battery cells 10 is a rechargeable secondary battery, and is composed of, for example, a lithium-ion battery in which lithium ions move between a positive electrode and a negative electrode. The plurality of battery cells 10 are divided into several groups, and each group is connected in series to form a module, and these modules are connected in series to form a high-voltage battery. The case 12 is made of a metal such as aluminum, but is not limited to this, and may be made of a resin such as glass fiber reinforced plastic (GFRP) or carbon fiber reinforced plastic (CRRP). The case is also composed of, for example, a tray 14 that forms the lower part and a cover 16 that forms the upper part, but is not limited to this.

[0023] [Key parts of the battery pack] The battery pack 1 according to this embodiment is provided with a gas outlet 18 in the case 12 for discharging gas blown out from the battery cell 10. The gas outlet 18 is not limited to one, but may be two or more. The number, position, size, and shape of the gas outlet 18 are arbitrarily set according to the amount of gas discharged from the battery cell 10 due to internal short circuits, etc. (predicted value) and the direction suitable for gas discharge. The gas outlet 18 is provided, for example, on the top or side surface of the case 12 facing the floor panel of the electric vehicle, but may also be provided on both the top and side surfaces of the case 12. The gas outlet 18 is provided along a preset gas discharge direction A. For example, the gas outlet 18 has a symmetrical shape with the gas discharge direction A, which is set as a straight line, as the axis of symmetry. The symmetrical shape is, for example, a rectangle, but is not limited to this.

[0024] Figure 2 is a schematic diagram showing the main parts of the battery pack 1 shown in Figure 1, and Figure 3 is a cross-sectional view of the main parts shown in Figure 2 along line III-III. As shown in Figures 2 and 3, the battery pack 1 includes a lid member 20 that closes the gas outlet 18, a first adhesive 22 and a second adhesive 24 that bond the lid member 20 to the case 12, and an opening control bar 26.

[0025] [Lid component] The lid member 20 is made of the same material as the case 12, for example, but may be made of a different material. The lid member 20 is formed larger than the gas outlet 18 so as to overlap with the edge of the gas outlet 18. The lid member 20 is formed to be similar in shape to the gas outlet 18, for example, but does not have to be similar in shape as long as it overlaps with the edge of the gas outlet 18. Also, the lid member 20 overlaps the edge of the gas outlet 18 more on the downstream side in the gas discharge direction than on the upstream side, for example, but is not limited to this.

[0026] The lid member 20 has a groove 28 provided along the predetermined gas discharge direction A of the gas outlet 18, but the groove 28 is not essential. The groove 28 is for forming a gas discharge passage, and when the lid member 20 separates from the case 12 due to the gas discharged from the gas outlet 18, a ridge is formed on the lid member 20 along the groove 28, and a gas discharge passage with a triangular cross-section is formed between the case 12 and the lid member 20.

[0027] [First adhesive and second adhesive] The first adhesive 22 adheres the lid member 20 to the case 12 on the upstream side of the predetermined gas discharge direction of the gas outlet 18, while the second adhesive 24 is an adhesive with a lower melting point than the first adhesive 22 and adheres the lid member 20 to the case 12 so that the case 12 becomes watertight. The first adhesive 22 is, for example, a heat-resistant adhesive and may also be a thermosetting adhesive. Of the first adhesive 22 and the second adhesive 24, at least the second adhesive 24 is a thermoplastic adhesive, but the first adhesive 22 may also be a thermoplastic adhesive if the first adhesive 22 has a higher melting point than the second adhesive 24. The first adhesive 22 is, for example, a resin adhesive such as polyethylene terephthalate or polyamide-imide, and the second adhesive 24 is, for example, a resin adhesive such as polyvinyl chloride, acrylic resin, polyethylene, or polystyrene. These are appropriately selected according to the temperature of the gas discharged from the gas outlet 18. Furthermore, if the case is provided with two or more gas outlets 18, they are appropriately selected according to the order (priority) in which the lid member 20 is opened. For example, the gas outlet 18 with a high priority for opening has its lid member 20 bonded to the case 12 with a second adhesive 24 that has a lower melting point, while the gas outlet 18 with a lower priority has its lid member 20 bonded to the case 12 with a second adhesive 24 that has a higher melting point.

[0028] The first adhesive 22 is used, for example, to bond the lid member 20 to the case 12 at two points that are separated from each other, but is not limited to this. The second adhesive 24 is applied, for example, to the outer edge of the gas outlet 18, excluding the portion where the first adhesive 22 is applied (the remaining portion), but is not limited to this.

[0029] [Opening degree control bar] The opening degree control bar 26 is a component for controlling the opening degree of the lid member 20, and is provided straddling the gas outlet 18 and connected to the case 12 at two points. For example, the opening degree control bar 26 extends in a direction perpendicular to the preset gas discharge direction A of the gas outlet 18, straddling the gas outlet 18 and connected to the case 12 at two points.

[0030] The opening control bar 26 gradually moves away from the surface of the case 12 toward the center from both side edges perpendicular to the preset gas discharge direction A of the gas outlet 18. For example, the opening control bar 26 is inclined diagonally toward the center from both side edges perpendicular to the preset gas discharge direction A of the gas outlet 18, but is not limited to this.

[0031] [Gas discharge operation] Figure 4 shows the state when high-temperature, high-pressure gas is discharged from the main part of the battery pack 1 shown in Figure 2, and Figure 5 is a cross-sectional view of the main part shown in Figure 4 along the VV line. When high-temperature, high-pressure gas is blown out of the battery cell 10 due to an internal short circuit or the like, the second adhesive 24 is melted by this gas, and the lid member 20 separates from the case 12 using the first adhesive 22 as a fulcrum. As a result, as shown in Figures 4 and 5, the lid member 20 opens to the extent that it does not interfere with the opening control bar 26, forming a ridge 32 along the groove 28, and an exhaust passage 30 is formed between the case 12 and the lid member 20. As a result, the high-temperature, high-pressure gas blown out from the battery cell 10 is discharged to the outside of the case 12 through the gas outlet 18 and the exhaust passage 30.

[0032] [Effects of the battery pack] According to the battery pack 1 of Embodiment 1, high-temperature, high-pressure gas ejected from the battery cell 10 due to an internal short circuit or the like melts the second adhesive 24, causing the lid member 20 to open to the extent that it interferes with the opening control bar 26, with the first adhesive 22 as the pivot point. Thus, the high-temperature, high-pressure gas ejected from the battery cell 10 can be discharged to the outside of the case 12 with a simple structure.

[0033] Furthermore, since the lid member 20 has a groove 28 provided along the predetermined gas discharge direction A of the gas outlet 18, the high-temperature, high-pressure gas discharged from the gas outlet 18 causes the lid member 20 to separate from the case 12, and a ridge 32 is formed on the lid member 20 along the groove 28, thereby forming a discharge passage 30. This makes it easier to efficiently discharge the high-temperature, high-pressure gas blown out from the battery cell 10. Also, if the lid member 20 overlaps the edge of the gas outlet 18 more significantly on the downstream side in the gas discharge direction than on the upstream side, the discharge passage 30 becomes longer, making it easier to discharge the gas in the desired direction.

[0034] Furthermore, the first adhesive 22 adheres the lid member 20 to the case 12 at two points separated from each other, making the lid member 20 more easily deformable between the two points, thus facilitating the formation of a discharge passage 30 for high-temperature, high-pressure gas. This allows for the efficient discharge of high-temperature, high-pressure gas blown out from the battery cell 10.

[0035] Furthermore, the opening control bar 26 gradually moves away from the surface of the case 12 toward the center from both side edges perpendicular to the preset gas discharge direction A of the gas outlet 18. As a result, the lid member 20 deforms along the opening control bar 26 due to the high-temperature, high-pressure gas blown out from the battery cell 10, making the cross-section of the discharge passage 30 formed by the lid member 20 triangular.

[0036] [Modified example of Embodiment 1] FIG. 6 is a diagram schematically showing a main part of the battery pack 1 according to a modified example of Embodiment 1. As shown in FIG. 6, the discharge direction of the gas from the gas discharge port 34 provided in the case 12 of the battery pack 1 according to the modified example of Embodiment 1 is set as a straight line, and the gas discharge port 34 gradually widens from the upstream side to the downstream side along the gas discharge direction B (L1 < L2). For example, the gas discharge port 34 is formed in an isosceles trapezoid having the straight-line set gas discharge direction as the axis of symmetry, but is not limited thereto, and may be formed in an isosceles triangle or a sector.

[0037] According to the battery pack 1 according to the modified example of Embodiment 1, since the cross-sectional area of the gas flow path of the gas blown out from the battery cell 10 expands from the upstream side to the downstream side in the gas discharge direction, the gas blown out from the battery cell 10 can be easily discharged efficiently.

[0038] [Embodiment 2] FIG. 7 is a diagram schematically showing a main part of the battery pack 1 according to Embodiment 2. The battery pack 1 according to Embodiment 2 is the same as the battery pack 1 according to Embodiment 1 except for the opening degree control bar 36. The same components as those of the battery pack 1 according to Embodiment 1 are denoted by the same reference numerals and the description thereof is omitted.

[0039] [Opening Degree Control Bar] As shown in FIG. 7, the opening degree control bar 36 according to Embodiment 2 is a member for controlling the opening degree of the lid member 20, is provided straddling the gas discharge port 18, and is connected to the case 12 at two locations. The opening degree control bar 36 extends, for example, in a direction orthogonal to the preset gas discharge direction A of the gas discharge port 18, straddles the gas discharge port 18, and is connected to the case 12 at two locations.

[0040] The opening degree control bar 36 is provided, for example, parallel to the surface of the case 12, extending from both side edges perpendicular to the preset gas discharge direction A of the gas outlet 18 toward the center. The opening degree control bar 36 has a recess 38 on the surface facing the lid member 20. The recess 38 is provided directly above a groove 28 in the lid member 20, and is designed so that the ridge formed along the groove as the lid member 20 deforms fits into it.

[0041] [Gas discharge operation] Figure 8 shows the state when high-temperature, high-pressure gas is discharged from the main part of the battery pack 1 shown in Figure 7. When high-temperature, high-pressure gas is blown out of the battery cell 10 due to an internal short circuit or the like, the second adhesive 24 is melted by this gas, and the lid member 20 separates from the case 12 using the first adhesive 22 as a fulcrum. As a result, as shown in Figure 8, the lid member 20 opens up to the extent that it does not interfere with the opening control bar 36, and a ridge 32 is formed along the groove 28, forming a discharge passage 30 between the case 12 and the lid member 20. The ridge 32 formed on the lid member 20 then fits into a recess 38 provided in the opening control bar 36, and the high-temperature, high-pressure gas blown out from the battery cell 10 is discharged to the outside of the case 12 through the gas outlet 18 and the discharge passage 30.

[0042] [Effects of the battery pack] According to the battery pack 1 of Embodiment 2, as the lid member 20 deforms, the ridge 32 formed along the groove 28 fits into the recess 38 of the opening control bar 36, thereby restricting the movement of the lid member 20 in a direction intersecting the preset gas discharge direction A of the gas outlet 18. [Explanation of Symbols]

[0043] 1 Battery pack 10 battery cells 12 cases 14 trays 16 Cover 18 Gas outlet 20 Lid member 22. First adhesive 24. Second adhesive 26. Opening angle control bar 28 Groove 30 Discharge passage 32 Ridges 34 Gas outlet 36. Opening angle control bar 38 recesses A,B Discharge direction

Claims

1. A battery pack in which multiple battery cells are housed in a case, The case is provided with a gas outlet for discharging gas blown out from the battery cell, A lid member that closes the gas outlet, A first adhesive is used to bond the lid member to the case on the upstream side of the predetermined gas discharge direction of the gas outlet, A second adhesive, which has a lower melting point than the first adhesive, is used to bond the lid member to the case so that the case becomes watertight. An opening control bar is provided across the aforementioned gas outlet and connected to the case at two points, A battery pack is included.

2. The lid member has a groove provided along the predetermined direction of gas discharge of the gas outlet. The battery pack according to claim 1.

3. The battery pack according to claim 2, wherein the first adhesive adheres the lid member to the case at two locations that are separated from each other.

4. The gas outlet is configured to gradually widen from the upstream side to the downstream side in the direction of discharge, along the predetermined direction of gas discharge of the gas outlet. A battery pack according to any one of claims 1 to 3.

5. The opening control bar moves gradually away from the surface of the case from both side edges perpendicular to the predetermined gas discharge direction of the gas outlet toward the center. The battery pack according to claim 3.

6. The opening control bar has a recess into which a ridge formed along the groove as the lid member deforms fits. The battery pack according to claim 3.

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