Battery pack

Abstract

One of a first case half and a second case half has at least one of a portion of a peripheral edge plate or a portion of a bottom plate configured so as to be recessed toward a housing space with respect to at least one of the outer surface of the other portion of the peripheral edge plate or the outer surface of the other portion of the bottom plate, whereby the recessed space that is recessed with respect to at least one of the outer surface of the other portion of the peripheral edge plate or the outer surface of the other portion of the bottom plate is provided on the outside of the case, and the entirety of a connection piping is provided inside the recessed space.

Description

Battery pack

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

[0002] In a battery pack in which battery cells are housed in a case, thermal management of the battery cells is important to suppress deterioration of the battery cells. Patent Document 1 discloses a cooling body that has a mounting surface on which battery cells are mounted and has refrigerant flow paths through which a refrigerant (e.g., water) flows, as a device for performing such thermal management. When multiple cooling bodies are provided in the case, connecting pipes are provided to communicate the refrigerant flow paths of each cooling body.

[0003] When the connecting pipes are installed inside the case, particularly when the connection between the connecting pipes and the cooling body is installed inside the case, if the connection becomes loose, the refrigerant may leak from the connection and accumulate inside the case, potentially damaging the battery cells. Therefore, regular inspections for refrigerant leaks are necessary, but if the connection is installed inside the case, inspections require opening the case and inspecting the inside of the case. In contrast, the battery pack described in Patent Document 1 has such connecting pipes installed outside the case, which prevents refrigerant from accumulating inside the case even if a refrigerant leaks, and allows inspection without opening the case.

[0004] Japanese Patent Application Laid-Open No. 2020-145046

[0005] However, in the battery pack of Patent Document 1, the connecting pipes provided on the outside of the case are arranged so as to protrude beyond the outer surface of the case. Therefore, when mounting the battery pack on a vehicle body, mounting space is required to accommodate the space for the connecting pipes that protrude beyond the outer surface of the case, which may cause issues with the installation of the battery pack.

[0006] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a battery pack with improved installation properties that can prevent refrigerant for cooling battery cells from accumulating inside the case even if it leaks.

[0007] In order to achieve the above object, a battery pack according to the present disclosure is a battery pack to be mounted on a vehicle, comprising: a case in which a storage space is formed by combining a first case half and a second case half; at least one battery cell housed in the storage space; at least two cooling bodies in which a refrigerant flow path is formed through which a refrigerant flows that cools the at least one battery cell by heat exchange with the at least one battery cell, the at least two cooling bodies being disposed within the storage space to sandwich the at least one battery cell and to be in contact with the at least one battery cell; at least two refrigerant pipes fixed to each of the at least two cooling bodies and constituting an inlet and an outlet of the refrigerant flow path of each of the at least two cooling bodies; and a connecting pipe that connects the refrigerant pipes fixed to two different cooling bodies, respectively, outside the case, and the first case half and the second case half each include a bottom plate portion and a peripheral plate portion fixed to the bottom plate portion so as to be bent relative to the bottom plate portion around the entire circumference of the peripheral portion of the bottom plate portion, and in either the first case half or the second case half, at least one of a part of the peripheral plate portion or a part of the bottom plate portion is configured to be recessed toward the storage space with respect to at least one of the outer surface of the other part of the peripheral plate portion or the outer surface of the other part of the bottom plate portion, thereby forming a recessed space on the outside of the case that is recessed with respect to at least one of the outer surface of the other part of the peripheral plate portion or the outer surface of the other part of the bottom plate portion, and the entire connecting pipe is arranged within the recessed space.

[0008] According to the battery pack of the present disclosure, the connecting pipes are arranged within the recessed space, so there is no need to provide space for the connecting pipes relative to the vehicle body structure or other on-board devices, etc., thereby improving the ease of installation of the battery pack.

[0009] Fig. 1 is a schematic cross-sectional view of a portion of a battery pack according to one embodiment of the present disclosure; Fig. 2 is a schematic view showing the arrangement of a cooling body inside a battery pack according to another embodiment of the present disclosure and the arrangement of a first connection part and a second connection part outside the battery pack; Fig. 3 is a cross-sectional view showing a portion of a second case half where a recessed space is formed in a battery pack according to yet another embodiment of the present disclosure; Fig. 4 is a cross-sectional view showing a portion of a second case half where a recessed space is formed in a battery pack according to yet another embodiment of the present disclosure; Fig. 5 is a cross-sectional view showing a portion of a second case half where a recessed space is formed in a battery pack according to yet another embodiment of the present disclosure.

[0010] Hereinafter, a battery pack according to an embodiment of the present disclosure will be described with reference to the drawings. The embodiment described below shows one aspect of the present disclosure, and is not intended to limit the present disclosure. Any modification can be made within the scope of the technical concept of the present disclosure.

[0011] The battery pack 1 according to one embodiment of the present disclosure shown in FIG. 1 is a battery pack mounted on a vehicle. The vehicle may be a battery electric vehicle (BEV) powered by a motor, or an electric vehicle such as a hybrid vehicle (HV) or a fuel cell vehicle (FCV) powered by an engine and a motor. A hybrid vehicle may be, for example, a plug-in hybrid vehicle (PHEV, PHV) that can be charged from an external power source or can externally supply power to an external device, but is not limited to a plug-in hybrid vehicle. The battery pack 1 may be mounted inside or outside the vehicle (for example, under the floor).

[0012] The battery pack 1 includes a case 2. The case 2 is configured by combining a first case half 3 and a second case half 4, and defines an internal storage space 5. The first case half 3 includes a bottom plate 3a and a peripheral plate 3b fixed to the bottom plate 3a so as to be bent relative to the bottom plate 3a around the entire periphery of a peripheral edge 3a1 of the bottom plate 3a. The first case half 3 may include a flange 3c formed by bending a portion including an edge 3b1 of the peripheral plate 3b. Similarly, the second case half 4 includes a bottom plate 4a and a peripheral plate 4b fixed to the bottom plate 4a so as to be bent relative to the bottom plate 4a around the entire periphery of a peripheral edge 4a1 of the bottom plate 4a. The second case half 4 may also include a flange 4c formed by bending a portion including an edge 4b1 of the peripheral plate 4b.

[0013] The first case half 3 and the second case half 4 can be assembled by matching the edge 3b1 of the peripheral plate 3b with the edge 4b1 of the peripheral plate 4b. As shown in Fig. 1, when the first case half 3 and the second case half 4 include flanges 3c and 4c, respectively, the first case half 3 and the second case half 4 are assembled by matching the flanges 3c and 4c. In this configuration, the first case half 3 and the second case half 4 are assembled by providing a sealing member 6, such as an O-ring, between the flanges 3c and 4c, and fastening members 7, such as bolts and nuts, to form a fixing portion 8 connecting the flanges 3c and 4c. In FIG. 1, the first case half 3 is depicted as being positioned above the second case half 4 in the vertical direction, but this is not limited to this configuration. The first case half 3 and the second case half 4 may be arranged upside down, or the first case half 3 and the second case half 4 may be combined with each other horizontally.

[0014] In the second case half 4, a portion of the peripheral plate 4b and a portion of the bottom plate 4a are configured to be recessed toward the storage space 5 relative to the outer surfaces of the remaining portions of the peripheral plate 4b and the bottom plate 4a, respectively, thereby forming a recessed space 10 on the outside of the case 2 that is recessed relative to the outer surfaces of the remaining portions of the peripheral plate 4b and the bottom plate 4a. In FIG. 1 , the recessed space 10 is formed by a recess in a portion of the second case half 4, but the recessed space 10 may also be formed by a recess in a portion of the first case half 3 similar to the above configuration. In the configuration of FIG. 1 where the fixing portion 8 is formed by connecting the flange portion 3c to the flange portion 4c, it is preferable that the recessed space 10 is configured to be located inside the fixing portion 8 when the battery pack 1 is viewed in a direction perpendicular to the bottom plate 3a of the first case half 3 (the direction of arrow A) or in a direction perpendicular to the bottom plate 4a of the second case half 4 (the direction of arrow B).

[0015] A battery module 12 including a plurality of battery cells 11 and a cooling body 13 that cools the battery module 12 are provided within the accommodation space 5. The battery pack 1 may be configured to accommodate at least one battery cell 11 within the accommodation space 5, rather than the battery module 12 being accommodated within the accommodation space 5. The cooling body 13 includes a first cooling body 14 and a second cooling body 15 that sandwich the battery module 12 and are provided so as to be in contact with the battery module 12. In a configuration in which the first case half 3 is located above the second case half 4 as shown in FIG. 1 , the battery module 12 can be placed on the second cooling body 15, and the first cooling body 14 can be placed on the battery module 12. Note that another battery module 12 or at least one battery cell 11 may also be placed on the first cooling body 14.

[0016] The first cooling body 14 and the second cooling body 15 are each formed with refrigerant flow paths 14a and 15a through which a refrigerant such as water flows. The first cooling body 14 and the second cooling body 15 are in contact with the battery modules 12, respectively, and therefore the battery modules 12 can be cooled by heat exchange between the refrigerant flowing through the refrigerant flow paths 14a and 15a and the battery modules 12. This allows thermal management of the battery cells 11 while the battery pack 1 is in operation.

[0017] Two refrigerant pipes 16 (first refrigerant pipes) that constitute an inlet for the refrigerant to flow into the refrigerant flow path 14a and an outlet for the refrigerant to flow out of the refrigerant flow path 14a are fixed to the first cooling body 14 so as to communicate with the refrigerant flow path 14a. Only the refrigerant pipe 16b that constitutes the outlet of the refrigerant flow path 14a is illustrated in FIG. 1 . Two refrigerant pipes 17 (second refrigerant pipes) that constitute an inlet for the refrigerant to flow into the refrigerant flow path 15a and an outlet for the refrigerant to flow out of the refrigerant flow path 15a are fixed to the second cooling body 15 so as to communicate with the refrigerant flow path 15a. Only the refrigerant pipe 17a that constitutes the inlet of the refrigerant flow path 15a is illustrated in FIG. 1 . Note that the first cooling body 14 and the second cooling body 15 are not limited to having two refrigerant pipes 16 and 17 fixed thereto. Three or more refrigerant pipes may be provided in each or either of the first cooling body 14 and the second cooling body 15, so that there are two or more refrigerant pipes that constitute the inlet or the outlet.

[0018] Refrigerant pipes 16 and 17 penetrate the wall of the case 2 and extend into the recessed space 10. In the embodiment shown in FIG. 1, refrigerant pipes 16b and 17a penetrate the wall of the second case half 4 and extend into the recessed space 10. Depending on the position where the recessed space 10 is formed, in the embodiment shown in FIG. 1, refrigerant pipe 16b extends into the recessed space 10 by penetrating a recessed portion of the peripheral plate 4b of the second case half 4, and refrigerant pipe 17a extends into the recessed space 10 by penetrating a recessed portion of the bottom plate 4a of the second case half 4. Refrigerant pipes 16b and 17a, which penetrate the wall of the second case half 4, are fixed to the wall of the second case half 4 by fixing plugs 18 and 19, respectively, made of rubber, resin, or the like. Fixing plugs 18 and 19 preferably have a structure that not only fixes refrigerant pipes 16b and 17a to the wall of second case half 4, but also completely blocks the holes through which refrigerant pipes 16b and 17a pass through the wall of second case half 4. This makes it possible to prevent water from entering case 2 through the holes.

[0019] The ends of refrigerant pipes 16b and 17a are located within recessed space 10, and refrigerant pipes 16b and 17a are connected within recessed space 10 by connecting pipes 20. Recessed space 10 is preferably configured by recessing a portion of peripheral plate 4b and a portion of bottom plate 4a so that connecting pipes 20 can be entirely positioned within recessed space 10. By disposing connecting pipes 20 entirely within recessed space 10, there is no need to provide space for connecting pipes 20 relative to the vehicle body structure or other on-board devices when mounting battery pack 1 on a vehicle. This reduces the mounting space for battery pack 1 and improves the ease of mounting battery pack 1.

[0020] In addition to this configuration, the recessed space 10 is positioned inside the fixing portion 8, which has an advantage when a collision load is applied to the battery pack 1 in a direction perpendicular to the arrow A or B (the horizontal direction in FIG. 1 or the direction perpendicular to the paper surface) during a vehicle collision. The fixing portion 8 is configured by combining two flange portions 3c and 4c. The direction perpendicular to the arrow A or B is perpendicular to the thickness direction of the flange portions 3c and 4c, so the fixing portion 8 has high rigidity in the direction of the collision load. In contrast, the thickness direction of the peripheral plate portions 3b and 4b is parallel to the direction of the collision load, so the rigidity of the peripheral plate portions 3b and 4b is low in the direction of the collision load. Therefore, when the collision load is applied to the highly rigid fixing portion 8, the collision load is less likely to be applied to the connecting pipe 20 in the recessed space 10 located inside the fixing portion 8. This reduces the risk of the connecting pipe 20 becoming detached from the refrigerant pipes 16b and 17a, resulting in refrigerant leakage.

[0021] Each of the refrigerant pipes 16b and 17a is connected to the connection pipe 20 by a first connection portion 21 that connects the refrigerant pipe 16b to the connection pipe 20 and a second connection portion 22 that connects the refrigerant pipe 17a to the connection pipe 20. The first connection portion 21 is formed, for example, by inserting the tip of the refrigerant pipe 16b into one end of the connection pipe 20 and fixing the inserted end with a fixing jig 23 such as a hose band. The second connection portion 22 is formed, for example, by inserting the tip of the refrigerant pipe 17a into the other end of the connection pipe 20 and fixing the inserted end with a fixing jig 24 such as a hose band.

[0022] When viewing the battery pack 1 in the direction of arrow A or B, the first connecting portion 21 and the second connecting portion 22 are preferably disposed at different positions relative to each other. If the first connecting portion 21 and the second connecting portion 22 were disposed at the same position, the connection pipe 20 would be connected to each of the refrigerant pipes 16b and 17a in a curved (or loosened) state. Depending on the size of the recessed space 10, a portion of the curved connection pipe 20 may be located outside the recessed space 10, which may reduce the effect of reducing the mounting space of the battery pack 1 compared to when the entire connection pipe 20 is located within the recessed space 10. In contrast, the above-described configuration allows the connection pipe 20 to be connected to each of the refrigerant pipes 16b and 17a without being curved, thereby reducing the risk of a portion of the connection pipe 20 being located outside the recessed space 10. As a result, the effect of reducing the mounting space of the battery pack 1 is reliably achieved.

[0023] 2 shows a schematic view of a portion of the internal configuration of a battery pack 1 according to another embodiment different from the above-described embodiment, viewed vertically from above to below (in the direction indicated by arrow A in FIG. 1 ). In a configuration in which the first cooling body 14 and the second cooling body 15 are positioned one above the other, the upper first cooling body 14 is often smaller than the lower second cooling body 15. This is because, in consideration of the overall balance of the battery pack 1, it is preferable that the battery modules 12 or battery cells 11 mounted on the upper first cooling body 14 be small, and because the battery modules 12 or battery cells 11 mounted on the upper first cooling body 14 are additionally provided in relation to the battery modules 12 or battery cells 11 mounted on the lower second cooling body 15 in order to increase the amount of power to be charged and discharged.

[0024] When first cooling body 14 is located above second cooling body 15, first connecting portion 21 is preferably disposed closer to peripheral edge 4a1 of bottom plate 4a of second case half 4 than second connecting portion 22. With this configuration, when first cooling body 14 located above is smaller than second cooling body 15 located below, connecting pipe 20 can be connected to refrigerant pipes 16b and 17a without bending connecting pipe 20, which reliably reduces the risk that part of connecting pipe 20 will be located outside recessed space 10, and as a result, the mounting space for battery pack 1 can be reliably reduced.

[0025] FIG. 3 shows a cross-sectional view of a portion of the second case half 4 where the recessed space 10 is formed in a battery pack 1 according to yet another embodiment. The angle θ formed between the first outer surface 31, which is the outer surface of the remaining portion of the bottom plate 4a, and the second outer surface 32, which is the outer surface of the portion of the second case half 4 that is recessed toward the storage space 5 to form the recessed space 10, is preferably smaller than 270°. To form the recessed space 10, the angle θ must be greater than 180°. However, the smaller the angle θ, i.e., the closer the angle θ is to 180°, the smaller the size of the recessed space 10 becomes. Therefore, the angle θ is preferably as large as possible within the range of greater than 180° and less than 270°. Therefore, the angle θ is preferably greater than 225°, more preferably greater than 240°, and most preferably greater than 260°. 3 illustrates a configuration in which the recess that forms the recessed space 10 is formed in the second case half 4, but it is preferable to use a configuration similar to that described above even when the recess that forms the recessed space 10 is formed in the first case half 3 (see FIG. 1). With such a configuration, the molded first case half 3 and second case half 4 can be easily removed from the mold when molding the first case half 3 and second case half 4, making the molding process more efficient.

[0026] In the battery pack 1 according to the above embodiment, a portion of the peripheral plate 4b and a portion of the bottom plate 4a are recessed toward the storage space 5 relative to the outer surfaces of the remaining portions of the peripheral plate 4b and the bottom plate 4a, respectively, to form the recessed space 10. However, this is not limiting. As shown in FIG. 4 , the recessed space 10 may be defined by only a portion of the bottom plate 4a being recessed toward the storage space 5 relative to the outer surfaces of the remaining portions of the bottom plate 4a. With this configuration, when the battery pack 1 is mounted on a vehicle such that the second case half 4 is positioned vertically below the first case half 3, the peripheral plate 4b is located outward in the vehicle width direction (to the left in the vehicle width direction in FIG. 4 ) from the wall portion 41 that defines the recessed space 10. Therefore, the peripheral plate 4b can protect the connection pipe 20 (see FIG. 1 ) even if mud, pebbles, or the like are thrown horizontally while the vehicle on which the battery pack 1 is mounted is traveling.

[0027] 5, the recessed space 10 may be formed by configuring only a portion of the peripheral plate 4b so that it is recessed toward the storage space 5 relative to the outer surface of the remaining portion of the peripheral plate 4b. With this configuration, the bottom plate 4a does not have a recess, so the bottom plate 4a is present below the recessed space 10. Therefore, the bottom plate 4a can protect the connection pipe 20 (see FIG. 1) even if mud, pebbles, etc. fly upward from below the vehicle while the vehicle equipped with the battery pack 1 is running.

[0028] REFERENCE SIGNS LIST 1 Battery pack 2 Case 3 First case half 3a Bottom plate portion (of first case half) 3a1 Peripheral edge portion (of bottom plate portion of first case half) 3b Peripheral edge portion (of first case half) 4 Second case half 4a Bottom plate portion (of second case half) 4a1 Peripheral edge portion (of bottom plate portion of second case half) 4b Peripheral edge portion (of second case half) 5 Storage space 8 Fixing portion 10 Recessed space 11 Battery cell 13 Cooling body 14 First cooling body 14a Refrigerant flow path 15 Second cooling body 15a Refrigerant flow path 16 Refrigerant piping (first refrigerant piping) 17 Refrigerant piping (second refrigerant piping) 20 Connection piping 21 First connection portion 22 Second connection portion 31 First outer surface 32 Second outer surface θ Angle (between the first outer surface and the second outer surface)

Claims

1. A battery pack to be mounted on a vehicle, comprising: a case formed by combining a first case half and a second case half to form an internal storage space; at least one battery cell housed within the storage space; at least two cooling bodies having a refrigerant flow path formed therein through which a refrigerant flows that cools the at least one battery cell by exchanging heat with the at least one battery cell, the at least two cooling bodies being disposed within the storage space to sandwich the at least one battery cell and to be in contact with the at least one battery cell; at least two refrigerant pipes fixed to each of the at least two cooling bodies and forming inlets and outlets of the refrigerant flow paths of the at least two cooling bodies; and connecting pipes connecting the refrigerant pipes fixed to two different cooling bodies of the at least two cooling bodies outside the case, wherein the first case half and the second case half each comprise: a bottom plate portion; and a peripheral plate portion fixed to the bottom plate portion along the entire periphery of the bottom plate portion so as to be bent relative to the bottom plate portion, In either the first case half or the second case half, at least one of a portion of the peripheral plate portion or a portion of the bottom plate portion is configured to be recessed toward the storage space relative to at least one of the outer surface of the other portion of the peripheral plate portion or the outer surface of the other portion of the bottom plate portion, thereby forming a recessed space on the outside of the case that is recessed relative to at least one of the outer surface of the other portion of the peripheral plate portion or the outer surface of the other portion of the bottom plate portion, and the entire connecting piping is arranged within the recessed space.

2. The battery pack according to claim 1, wherein the first case half and the second case half each have a flange portion formed by bending a portion including an edge portion of the respective peripheral plate portion, the first case half and the second case half are combined so that the flange portions are connected to each other to form a fixing portion, and when the battery pack is viewed in a direction perpendicular to the bottom plate portion of the first case half or the second case half, the recessed space is located inside the fixing portion.

3. A battery pack as described in claim 1 or 2, wherein, when the battery pack is viewed in a direction perpendicular to the bottom plate portion of the first case half or the second case half, a first connection portion connecting one of the refrigerant pipes to the connecting pipe and a second connection portion connecting the other of the refrigerant pipes to the connecting pipe are arranged in different positions relative to each other.

4. A battery pack as claimed in claim 3, wherein the first case half is positioned above the second case half in the vertical direction, and at least one of a portion of the peripheral plate portion or a portion of the bottom plate portion of the second case half is configured to be recessed toward the storage space with respect to at least one of the outer surface of another portion of the peripheral plate portion or the outer surface of another portion of the bottom plate portion, respectively, thereby forming the recessed space, the two different cooling bodies comprise a first cooling body and a second cooling body positioned vertically below the first cooling body, the first connecting part connects the first refrigerant piping fixed to the first cooling body to the connecting piping, and the second connecting part connects the second refrigerant piping fixed to the second cooling body to the connecting piping, and the first connecting part and the second connecting part are arranged such that, when the battery pack is viewed in a direction perpendicular to the bottom plate portion of the first case half or the second case half, the first connecting part is located closer to the peripheral portion of the bottom plate portion of the second case half than the second connecting part.

5. A battery pack as described in claim 1 or 2, wherein the first case half is positioned above the second case half in the vertical direction, and only a portion of the bottom plate portion of the second case half is configured to be recessed relative to at least one outer surface of the other portion of the bottom plate portion of the second case half, thereby configuring the recessed space to be recessed toward the storage space relative to the outer surface of the other portion of the bottom plate portion.

6. A battery pack as claimed in claim 1 or 2, wherein in either the first case half or the second case half, a portion of the peripheral plate portion and a portion of the bottom plate portion are configured to be recessed towards the storage space relative to the outer surfaces of the remaining portions of the peripheral plate portion and the bottom plate portion, respectively, thereby forming the recessed space, and wherein in either the first case half or the second case half which includes the portion of the peripheral plate portion and the portion of the bottom plate portion recessed towards the storage space, an angle formed by a first outer surface which is the outer surface of the remaining portion of the bottom plate portion and a second outer surface which is the outer surface of the portion recessed towards the storage space is smaller than 270°.

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