Battery pack

Abstract

This battery pack (1) comprises a battery cell (11) and a housing (20) that houses the battery cell (11). The housing (20) has a flange (24) fastened to a vehicle member (2) by a clinching nut (31) and a bolt (32). The flange (24) defines a recess (241) in which the clinching nut (31) and at least a portion of the bolt (32) are accommodated. The flange (24) defines a notch (243) that communicates with the internal space of the recess (241) and the external space around the recess (241).

Description

Battery Pack

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

[0002] In recent years, various battery packs have been developed. A battery pack includes a battery cell and a housing that accommodates the battery cell.

[0003] Patent Document 1 describes a drain hole structure for a vehicle component. This structure includes a passage that communicates between the space inside a container forming a predetermined space and the outside air. The passage has a first outer hole and a second outer hole disposed above the first outer hole in the direction of gravity.

[0004] Japanese Unexamined Patent Publication No. 10-61508

[0005] In a battery pack, a housing that accommodates battery cells sometimes has a structure such as a flange that is fastened to an external structure such as a vehicle frame by fasteners such as bolts and nuts. The structure may define a recess that accommodates at least a portion of the fastener. However, when moisture such as condensed water or rainwater accumulates in the recess, deterioration such as rust may occur in the structure of the housing and the external structure to which the structure is fastened.

[0006] An example of the object of the present invention is to make it difficult for moisture to accumulate in a recess that accommodates at least a portion of a fastener for fastening a housing accommodating battery cells and an external structure to each other. Other objects of the present invention will become apparent from the description of the present specification.

[0007] One aspect of the present invention is as follows: 1. A battery pack comprising: a battery cell; and a housing for housing the battery cell, wherein the housing has a structure fastened to an external structure by a fastener, the structure defines a recess into which at least a portion of the fastener is housed, and the structure defines a communication space communicating with the internal space of the recess and the external space surrounding the recess. 2. The battery pack according to 1, wherein the bottom of the communication space is at least partially recessed from the bottom of the recess, or slopes at least partially downward as it moves away from the recess. 3. The battery pack according to 1 or 2, wherein the width of the communication space is at least partially wider as it moves away from the bottom of the communication space.

[0008] According to the above embodiment of the present invention, moisture is less likely to accumulate in the recess in which at least a portion of the fastener for fastening the housing containing the battery cell and the external structure to each other is housed.

[0009] This is a top view of the battery pack according to the embodiment. This is a top view of the battery pack according to the embodiment with the upper case removed. This is an enlarged perspective view of the flange according to the embodiment. This is an enlarged perspective view of the flange according to the embodiment with the clinching nut removed. This figure shows a cross-section of the flange along line A-A in Figure 3, along with the cross-sections of the vehicle member and the bolt. This is a diagram showing a first modified example of Figure 5. This is a diagram showing a second modified example of Figure 5.

[0010] Embodiments and modified examples of the present invention will be described below with reference to the drawings. In all drawings, similar components are denoted by the same reference numerals, and their descriptions are omitted where appropriate.

[0011] Figure 1 is a top view of the battery pack 1 according to an embodiment. Figure 2 is a top view of the battery pack 1 according to an embodiment with the upper case 23 removed.

[0012] In this embodiment, the battery pack 1 is mounted in an automobile. Specifically, the battery pack 1 is mounted between the front and rear wheels of the automobile. Hereafter, unless otherwise specified, the battery pack 1 will be described as being mounted in an automobile. However, the battery pack 1 can also be applied to applications other than automobiles.

[0013] Figures 1 and 2 show the X-axis, Y-axis, and Z-axis, respectively, for illustrative purposes. In Figures 1 and 2, the white circle with a black dot indicating the Z-axis indicates that the Z-axis arrow is pointing towards the viewer. The X-axis indicates the front-to-back direction of the battery pack 1. The Y-axis is one of the directions perpendicular to the X-axis. The Y-axis indicates the left-to-right direction of the battery pack 1. The Z-axis is a direction perpendicular to both the X-axis and Y-axis. The Z-axis indicates the up-to-down direction of the battery pack 1. The directions indicated by the tip of the X-axis arrow, the Y-axis arrow, and the Z-axis arrow indicate the rear, right, and up directions of the battery pack 1, respectively. The relationship between the X-axis, Y-axis, and Z-axis and the front-to-back, left-to-right, and up-to-down directions of the battery pack 1 is not limited to this example.

[0014] In this embodiment, the front-to-back, left-to-right, and up-to-down directions of the battery pack 1 are determined by the vehicle on which the battery pack 1 is mounted. The X, Y, and Z directions represent the front-to-back, left-to-right, and up-to-down directions of the vehicle, respectively. The directions indicated by the tip of the X-axis arrow, the Y-axis arrow, and the Z-axis arrow indicate the rear, right, and up directions of the vehicle, respectively. However, the relationship between the front-to-back, left-to-right, and up-to-down directions of the battery pack 1 and the front-to-back, left-to-right, and up-to-down directions of the vehicle is not limited to this example.

[0015] Unless otherwise specified, the +X side or +X refers to the side indicated by the tip of the X-axis arrow, and the -X side or -X refers to the opposite side of the side indicated by the tip of the X-axis arrow. Unless otherwise specified, the +Y side or +Y refers to the side indicated by the tip of the Y-axis arrow, and the -Y side or -Y refers to the opposite side of the side indicated by the tip of the Y-axis arrow. Unless otherwise specified, the +Z side or +Z refers to the side indicated by the tip of the Z-axis arrow, and the -Z side or -Z refers to the opposite side of the side indicated by the tip of the Z-axis arrow.

[0016] As shown in Figures 1 and 2, the battery pack 1 according to this embodiment comprises a plurality of battery modules 10 and a housing 20.

[0017] In the example shown in Figure 2, the battery pack 1 comprises four battery modules 10 arranged in two rows and two columns in the X and Y directions, respectively, and one battery module 10 arranged on the +X side relative to the four battery modules 10. The number and arrangement of the battery modules 10 are not limited to the example shown in Figure 2. In the example shown in Figure 2, each of the four battery modules 10 has a plurality of battery cells 11 stacked in the Y direction. In the example shown in Figure 2, each of the battery cells 11 in the four battery modules 10 has a longitudinal direction in the X direction, a short direction in the Z direction, and a thickness direction in the Y direction. In the example shown in Figure 2, the single battery module 10 has a plurality of battery cells 11 stacked in the X direction. In the example shown in Figure 2, the battery cells 11 in the single battery module 10 have a longitudinal direction in the Y direction, a short direction in the Z direction, and a thickness direction in the X direction. In each battery module 10, the plurality of battery cells 11 are electrically connected in series, parallel, or a combination of series and parallel. The number and arrangement of the multiple battery cells 11 in each battery module 10 are not limited to the example shown in Figure 2.

[0018] Each battery module 10 may have a separate housing for housing multiple battery cells 11, in addition to the housing 20. Specifically, each battery module 10 may be housed in the housing 20 with the multiple battery cells 11 of each battery module 10 housed in a different housing from the housing 20. Alternatively, each battery module 10 does not need to have a housing for housing multiple battery cells 11. Specifically, the multiple battery cells 11 of each battery module 10 may be directly housed in the housing 20.

[0019] The housing 20 houses multiple battery modules 10. As shown in Figures 1 and 2, the housing 20 has a lower plate 21, a frame 22, an upper case 23, and multiple flanges 24. The frame 22 includes a side frame 221 and a support frame 222.

[0020] As shown in Figure 2, the lower plate 21 is positioned substantially perpendicular to the Z direction. The multiple battery modules 10 are located on the +Z side of the lower plate 21. Therefore, the multiple battery modules 10 and the lower plate 21 overlap each other at least partially in the Z direction. In the example shown in Figure 2, when viewed from the +Z side, the lower plate 21 has a substantially rectangular shape with a pair of long sides substantially parallel to the X direction and a pair of short sides substantially parallel to the Y direction, with its four corners cut off. In other words, when viewed from the +Z side, the lower plate 21 has a substantially octagonal shape. The shape of the lower plate 21 is not limited to the example shown in Figure 2. A flow path for fluid to regulate the temperature of the multiple battery modules 10 is provided inside the lower plate 21.

[0021] The side frame 221 is located on the +Z side with respect to the +Z plane of the lower plate 21. Viewed from the +Z side, the side frame 221 extends along the outer circumference of the lower plate 21, except for the right front corner and the left front corner of the lower plate 21. The lower plate 21 and the side frame 221 are fastened to each other by fasteners such as bolts.

[0022] The support frame 222 is located on the +Z side with respect to the +Z plane of the lower plate 21. As shown in Figure 2, when viewed from the +Z side, the support frame 222 is located within the area enclosed by the side frame 221 and at least partially encloses each of the multiple battery modules 10. The lower plate 21 and the support frame 222 are fastened to each other by fasteners such as bolts. Each battery module 10 and the support frame 222 are fastened to each other by fasteners such as bolts.

[0023] As shown in Figure 1, the upper case 23 is positioned substantially perpendicular to the Z direction. The upper case 23 is located on the +Z side relative to the multiple battery modules 10 and the frame 22. The portion of the side frame 221 and the upper case 23 that overlaps with the side frame 221 in the Z direction is fastened to each other by fasteners such as bolts, with a seal placed between the +Z plane of the side frame 221 and the -Z plane of the upper case 23. With the portions of the side frame 221 and the upper case 23 that overlap with the side frame 221 in the Z direction fastened to each other, the lower plate 21, the frame 22, and the upper case 23 define a housing space for accommodating the multiple battery modules 10.

[0024] In the examples shown in Figures 1 and 2, the multiple flanges 24 protrude from the right rear diagonal edge and the left rear diagonal edge of the side frame 221. The number and position of the flanges 24 are not limited to the examples shown in Figures 1 and 2.

[0025] Figure 3 is an enlarged perspective view of the flange 24 according to the embodiment. Figure 4 is an enlarged perspective view of the flange 24 according to the embodiment with the clinching nut 31 removed. Figure 5 is a diagram showing a cross-section of the flange 24 along line A-A in Figure 3, together with the cross-sections of the vehicle member 2 and the bolt 32. The flange 24 shown in Figures 3 and 4 is the flange 24 that protrudes from the diagonal left rear side of the side frame 221 in Figure 1. The matters described regarding the flange 24 with reference to Figures 3 to 5 are also applicable to flanges 24 other than the flange 24 shown in Figures 3 and 4.

[0026] As shown in Figures 3 and 4, the flange 24 according to the embodiment defines a plurality of recesses 241 and a plurality of through holes 242. In the example shown in Figures 3 and 4, two recesses 241 are aligned along the outer edge 24a of the flange 24. Viewed from the +Z side, each recess 241 is substantially circular in shape. The through holes 242 are located approximately in the center of the bottom of the recess 241 on the -Z side. The through holes 242 extend through the flange 24 in the Z direction. Viewed from the +Z side, the through holes 242 are substantially circular in shape. The shape, number, and position of the recesses 241 and through holes 242 are not limited to the example shown in Figures 3 and 4.

[0027] As shown in Figure 5, the flange 24 and the vehicle member 2 are fastened together by a clinching nut 31 and a bolt 32. The clinching nut 31 and the bolt 32 are made of, for example, metal. The clinching nut 31 includes a nut head 311 and a shank 312. The bolt 32 includes a bolt head 321 and a shaft 322. In this embodiment, the vehicle member 2 is a vehicle component on which the battery pack 1 is mounted. In the example shown in Figure 5, the vehicle member 2 has a plate shape substantially perpendicular to the Z direction. The clinching nut 31 and the bolt 32 are fasteners for fastening the flange 24 and the vehicle member 2 together. A rivet nut may be used instead of the clinching nut 31.

[0028] As shown in Figure 5, the nut head 311 is housed in the recess 241 with the shank 312 press-fitted into the through hole 242. Therefore, the portion of the flange 24 defining the recess 241 makes it easier to shield the nut head 311 from surrounding members. Thus, compared to the case where the nut head 311 is provided on a simple flat surface of the flange 24, it is easier to suppress contact or collision between the nut head 311 and the members surrounding the nut head 311. Thus, it is easier to suppress loosening of the clinching nut 31 and bolt 32 due to contact or collision between the nut head 311 and the members surrounding the nut head 311.

[0029] The shaft 322 protrudes from the bolt head 321 toward the +Z side with the nut head 311 positioned toward the -Z side of the vehicle member 2. The shaft 322 is inserted through the mounting hole 2a of the vehicle member 2 into the clinching nut 31. The flange 24 and the vehicle member 2 are fastened together by tightening the clinching nut 31 and the bolt 32 together. The battery pack 1 and the vehicle member 2 are fixed together by fastening the flange 24 and the vehicle member 2 together.

[0030] As shown in Figures 3 and 4, the flange 24 defines a notch 243 that communicates with the outer edge 24a side of the internal space of the recess 241 and with the external space located outside the outer edge 24a. The notch 243 is a communication space that connects the internal space of the recess 241 and the external space surrounding the recess 241. Therefore, moisture such as condensation and water inside the recess 241 can be discharged through the notch 243. Thus, moisture is less likely to accumulate in the recess 241 compared to a case where the notch 243 is not provided. By making it less likely for moisture to accumulate in the recess 241, deterioration such as rust can be less likely to occur on metals such as the flange 24, clinching nut 31, bolt 32, and vehicle component 2.

[0031] In this embodiment, moisture inside the recess 241 can be discharged not through a hole at the bottom of the recess 241 on the -Z side, but through a notch 243 located on the side of the recess 241. If a hole for draining moisture were provided at the bottom of the recess 241 on the -Z side, the contact area between the -Z surface of the nut head 311 and the bottom surface of the recess 241 would be reduced by the amount of the hole, making it difficult to obtain sufficient torque for the clinching nut 31 and bolt 32. In this embodiment, sufficient torque for the clinching nut 31 and bolt 32 can be obtained by ensuring the contact area between the -Z surface of the nut head 311 and the bottom surface of the recess 241. Furthermore, if a hole for draining moisture were provided at the bottom of the recess 241 on the -Z side, the strength of the flange 24 might be reduced by the hole, or the hole might become the starting point for cracks in the flange 24. In this embodiment, by eliminating the provision of a hole for draining moisture at the bottom of the recess 241 on the -Z side, it is possible to suppress a decrease in the strength of the flange 24 and cracking of the flange 24.

[0032] In this embodiment, as can be seen from Figures 4 and 5, the bottom of the notch 243 on the -Z side is recessed to the -Z side at least partially more than the bottom of the recess 241 on the -Z side. Therefore, compared to the case where the bottom of the recess 241 and the bottom of the notch 243 are located on the same plane perpendicular to the Z direction, it is possible to more easily drain moisture from inside the recess 241 through the notch 243. The bottom of the recess 241 and the bottom of the notch 243 may be located on the same plane perpendicular to the Z direction.

[0033] As shown in Figures 3 and 4, the width of the notch 243 in the direction parallel to the outer edge 24a widens at least partially as it moves away from the bottom of the notch 243 towards the +Z side. Therefore, compared to the case where the width of the notch 243 is substantially constant regardless of its position in the Z direction, it is possible to remove the mold used to form the notch 243 from the notch 243 during molding of the flange 24. Furthermore, compared to the case where the width of the notch 243 is relatively narrow throughout the entire Z direction, it is possible to drain the portion of the recess 241 where the water level is high and a large amount of water has accumulated inside.

[0034] In this embodiment, the flange 24 is a structure fastened to the vehicle member 2 by a clinching nut 31 and a bolt 32. This structure is not limited to the flange 24, but can be any part of the housing 20.

[0035] In this embodiment, the vehicle member 2 is an external structure to which the flange 24 is attached. The external structure is not limited to the vehicle member 2. For example, when the battery pack 1 is used for an application other than that of an automobile, the same fastening method as that used for fastening the flange 24 and the vehicle member 2 can be used to fasten the battery pack 1 and the device on which the battery pack 1 is mounted.

[0036] Figure 6 shows a first modified example of Figure 5. The modified example shown in Figure 6 is the same as the embodiment shown in Figure 4, except for the following points.

[0037] As shown in Figure 6, the bottom of the notch 243 on the -Z side may be at least partially inclined downward as it moves away from the recess 241. In the example shown in Figure 6, compared to the case where the bottom of the recess 241 and the bottom of the notch 243 are located on the same plane perpendicular to the Z direction, it is possible to drain moisture from inside the recess 241 through the notch 243.

[0038] Figure 7 shows a second modified example of Figure 5. The modified example shown in Figure 7 is the same as the embodiment shown in Figure 4, except for the following points.

[0039] In the example shown in Figure 7, the bolt 32A includes a bolt head 321A and a shaft 322A. The nut 31A is located on the -Z side relative to the vehicle member 2. The bolt head 321A is housed in the recess 241 with the shaft 322A inserted through the through hole 242 and the mounting hole 2a into the nut 31A. The flange 24 and the vehicle member 2 are fastened together by tightening the nut 31A and the bolt 32A together. Therefore, the nut 31A and the bolt 32A serve as fasteners for fastening the flange 24 and the vehicle member 2 together. In the example shown in Figure 7, as in the embodiment, moisture is less likely to accumulate in the recess 241 compared to the case where the notch 243 is not provided.

[0040] Instead of the nut 31A and the bolt 32A, the flange 24 and the vehicle member 2 may be fastened to each other by a screw screwed into the mounting hole 2a. When a screw is used, the head of the screw is accommodated in the recess 241. Even when the screw head is accommodated in the recess 241, this configuration can make it harder for water to accumulate in the recess 241 compared to a case where the notch 243 is not provided.

[0041] The embodiments and modifications of the present invention have been described above with reference to the drawings, and these are merely examples of the present invention. Various configurations other than those described above can also be adopted.

[0042] In the embodiments and modifications, the battery pack 1 is mounted on an automobile. The target on which the battery pack 1 is mounted is not limited to automobiles, but is all types of moving objects. That is, the target to which the flange 24 is fastened is not limited to the vehicle member 2, but is all members of moving bodies. Examples of the moving body include vehicles such as automobiles and motorcycles, as well as trains, ships, drones, and airplanes. When the battery pack 1 is mounted on a moving body, even if water accumulates in the recess 241, the water is discharged through the notch 243 due to the movement of the moving body and the vibration and inclination accompanying the movement of the moving body.

[0043] A case where the moving body on which the battery pack 1 is mounted is an automobile will be described. In an automobile, vibration occurs due to factors such as starting of the automobile, for example. Therefore, even if water is retained by surface tension in the gap between the inner wall of the recess 241 and a fastener such as the clinching nut 31 and bolt 32 according to the embodiment or the nut 31A and bolt 32A according to the modification, the vibration causes the water to move through the gap. When the water moves until it reaches the notch 243, the water can be discharged through the notch 243.

[0044] This application claims priority based on Japanese Patent Application No. 2025-042231 filed on March 17, 2025, and the entire disclosure thereof is incorporated herein.

[0045] 1 Battery pack, 2 Vehicle component, 2a Mounting hole, 10 Battery module, 11 Battery cell, 20 Housing, 21 Lower plate, 22 Frame, 221 Side frame, 222 Support frame, 23 Upper case, 24 Flange, 24a Outer edge, 241 Recess, 242 Through hole, 243 Notch, 31 Clinching nut, 311 Nut head, 312 Shank, 31A Nut, 32, 32A Bolt, 321, 321A Bolt head, 322, 322A Shaft

Claims

1. A battery pack comprising: a battery cell; and a housing for housing the battery cell, wherein the housing has a structure fastened to an external structure by fasteners; the structure defines a recess into which at least a portion of the fasteners are housed; and the structure defines a communication space communicating with the internal space of the recess and the external space surrounding the recess.

2. The battery pack according to claim 1, wherein the bottom of the communication space is at least partially recessed from the bottom of the recess, or is at least partially sloped downward as it moves away from the recess.

3. The battery pack according to claim 1 or 2, wherein the width of the communication space is at least partially wider as it moves away from the bottom of the communication space.

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