Battery pack

Abstract

To reduce the size and cost of a battery pack.SOLUTION: A battery pack 1 includes a plurality of battery cells 21, a case 3 that houses the plurality of battery cells 21 arranged in a stacked state, and a restraining member 4 that restrains the plurality of battery cells 21 to the case 3. An opening 311b that communicates between the inside and outside of the case 3 is provided on the side of the case 3. The restraining member 4 is wound in a circumferential direction following the outer surface of the case 3, and restrains the plurality of battery cells 21 to the case 3 while applying a restraining load to the plurality of battery cells 21 inside the case 3 via the opening 311b.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] BACKGROUND ART Conventionally, a battery pack is known that includes a plurality of battery cells and a case that houses the plurality of battery cells arranged in a stacked state (see, for example, Patent Document 1).

[0003] In the battery pack described in Patent Document 1, a pair of end plates and a plurality of restraining members are used to stack a plurality of battery cells. Specifically, the end plates are disposed at one end and the other end of the plurality of battery cells in the stacking direction. The restraining members are disposed on the outer surfaces of the plurality of battery cells along the stacking direction of the plurality of battery cells. The end plates and the restraining members are connected to each other, and are arranged around the entire circumferential direction following the outer surfaces of the plurality of battery cells. The stacked plurality of battery cells are then housed in a case. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6724300 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the battery pack described in Patent Document 1, the end plates and restraining members are made of metal, and the end plates and restraining members are joined together by welding to stack multiple battery cells. Therefore, the high temperature generated during the welding is transferred to the battery cells, which may damage them.

[0006] To protect the battery cells from heat during welding, it is conceivable to provide a heat insulating member (for example, by providing a heat insulating layer inside the battery cells). However, if such a heat insulating member is used, the size of the stacked battery cells increases by the amount of the heat insulating member provided, resulting in an increase in the size of the battery pack.

[0007] In addition, in order to prevent the stacked battery cells from shifting positions inside the case, it is possible to use an adhesive to fix the stacked battery cells inside the case. However, when using such an adhesive, it is difficult to reduce the cost of the battery pack due to the process of applying the adhesive and the material cost of the adhesive.

[0008] Therefore, there is a demand for a technology that can eliminate the need for welding or adhesive fixation and that can reduce the size and cost of battery packs.

[0009] The present invention has been made in view of the above, and has an object to provide a battery pack that can be made smaller and less expensive. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems and achieve the object, the battery pack of the present invention comprises a plurality of battery cells, a case in which the plurality of battery cells are housed in a stacked arrangement, and a restraining member that restrains the plurality of battery cells to the case, wherein an opening that penetrates the inside and outside of the case is provided on the side of the case, and the restraining member is wound in a circumferential direction following the outer surface of the case, and restrains the plurality of battery cells to the case while applying a restraining load to the plurality of battery cells inside the case via the opening.

[0011] In the battery pack according to the present invention, in the above invention, the restraining member applies the restraining load in the stacking direction of the plurality of battery cells.

[0012] In addition, in the battery pack of the present invention, in the above invention, the restraint member is made of an elastic material and includes an elastic plate that abuts against the battery cell through the opening, a pressure cover that is arranged to close the opening and abuts against the elastic plate, and a restraint band that is assembled to the outer surface of the case and connected to the pressure cover, thereby restraining the multiple battery cells to the case with a restraint load applied to the multiple battery cells via the pressure cover and the elastic plate.

[0013] In addition, in the battery pack of the present invention, in the above invention, the restraint member further includes a first reinforcing plate assembled to the outer surface of the case, and the restraint band includes a first restraint band connecting first end portions of the pressing cover and the first reinforcing plate that are adjacent to each other in the circumferential direction, and a second restraint band connecting second end portions of the pressing cover and the first reinforcing plate that are adjacent to each other in the circumferential direction.

[0014] In addition, in the battery pack of the present invention, in the above invention, one end of the restraint band is connected to a first end on one end side of the circumferential direction of the pressure cover, extends in the circumferential direction along the outer surface of the case, and the other end is connected to a second end on the other end side of the pressure cover in the circumferential direction.

[0015] In addition, in the battery pack of the present invention, in the above invention, the pressing cover comprises an end plate made of a resin material and a second reinforcing plate made of a metal material, the end plate abutting against the elastic plate, and the second reinforcing plate facing the elastic plate across the end plate.

[0016] In the battery pack according to the present invention, in the above invention, the pressing lid is made of a metal material. [Effects of the Invention]

[0017] The battery pack according to the present invention has the effect of being miniaturized and cost-reduced. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram illustrating a battery pack according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating a battery pack according to an embodiment. [Figure 3] FIG. 3 is a diagram illustrating a battery pack according to an embodiment. [Figure 4] FIG. 4 is a diagram illustrating a battery pack according to an embodiment. [Figure 5] FIG. 5 is a diagram illustrating a battery pack according to an embodiment. [Figure 6] FIG. 6 is a diagram showing a battery stack. [Figure 7] FIG. 7 is a diagram showing a battery cell. [Figure 8] FIG. 8 is a diagram showing the first resin frame. [Figure 9] FIG. 9 is a diagram showing the first resin frame. [Figure 10] FIG. 10 is a diagram illustrating a first modification of the embodiment. [Figure 11] FIG. 11 is a diagram illustrating a first modification of the embodiment. [Figure 12] FIG. 12 is a diagram illustrating a first modification of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, with reference to the drawings, a description will be given of a mode for carrying out the present invention (hereinafter, referred to as an embodiment). Note that the present invention is not limited to the embodiment described below. Furthermore, in the drawings, the same parts are given the same reference numerals. Furthermore, the drawings are schematic, and the dimensional relationships and ratios of the elements may differ from the actual situation. Furthermore, the drawings may include parts whose dimensional relationships and ratios differ from each other.

[0020] [General configuration of the battery pack] 1 to 5 are diagrams illustrating a battery pack 1 according to a first embodiment. Specifically, FIG. 1 is an overall perspective view of the battery pack 1. In FIG. 1, the Z axis indicates an axis parallel to the vertical direction (the +Z axis side is the upper side, and the -Z axis side is the lower side). The X axis and the Y axis are two axes perpendicular to the Z axis. Furthermore, the Y axis is an axis parallel to the thickness direction of the battery cell 21. The X axis, Y axis, and Z axis are also used in FIG. 2 and subsequent figures. FIG. 2 is a view of the battery pack 1 as seen from the +Y axis side. FIG. 3 is a view of the battery pack 1 as seen from the -Y axis side. FIG. 4 is an exploded perspective view of the battery pack 1. FIG. 5 is a cross-sectional view taken along line VV of FIG. 2. The battery pack 1 is mounted on, for example, an electric vehicle, and is capable of charging with electricity from an external source and discharging electricity to the outside. As shown in Figures 1 to 5, the battery pack 1 includes a battery stack 2 (Figures 4 and 5), a case 3, and a restraining member 4.

[0021] [Battery stack configuration] FIG. 6 is a diagram showing the battery stack 2. As shown in FIG. As shown in FIG. 6, the battery stack 2 comprises a plurality of (four in this embodiment) battery cells 21 and a resin frame 22, and the plurality of battery cells 21 are stacked in a layered arrangement in the thickness direction of the battery cells 21 (direction along the Y axis) by the resin frame 22.

[0022] FIG. 7 is a diagram showing the battery cell 21. As shown in FIG. As shown in FIG. 7, the battery cell 21 is configured such that the internal electrodes, separators, and the like (not shown) that constitute the battery cell 21 are housed in an exterior case 211.

[0023] The exterior case 211 is made of a metal material such as aluminum, and as shown in FIG. 7, is a rectangular hollow member having a pair of abdominal surface portions 211a, 211b, a pair of side surface portions 211c, 211d, a bottom surface portion 211e, and a top surface portion 211f.

[0024] Here, the pair of abdominal surface portions 211a, 211b are wall portions that are perpendicular to the thickness direction of the battery cell 21 (direction along the Y axis) and face each other. The pair of side surface portions 211c, 211d are wall portions that are parallel to the thickness direction of the battery cell 21 and face each other along the X axis. The bottom surface portion 211e is a wall portion that is perpendicular to the height direction of the battery cell 21 (direction along the Z axis). The top surface portion 211f is a wall portion that is perpendicular to the height direction of the battery cell 21 and faces the bottom surface portion 211e.

[0025] 7, a pair of electrode terminals 212 are provided on the upper surface portion 211f. One of the pair of electrode terminals 212 is a positive terminal, and the other is a negative terminal.

[0026] The battery cell 21 described above expands or contracts depending on its state of charge, etc. The expansion and contraction deformation occurs along the thickness direction of the battery cell 21.

[0027] The resin frame 22 is made of an electrically insulating resin material and serves to mitigate (protect) the effects of impacts and loads on the battery cells 21. As shown in Fig. 6, the resin frame 22 includes a plurality of (three in this embodiment) first resin frames 22A and a second resin frame 22B.

[0028] 8 and 9 are diagrams showing the first resin frame 22A. Specifically, Fig. 8 is a perspective view of the first resin frame 22A as seen from the +Y axis side. Fig. 9 is a perspective view of the first resin frame 22A as seen from the -Y axis side. As shown in FIGS. 8 and 9, the first resin frame 22A includes a partition plate 221, a first frame portion 222, and a second frame portion 223.

[0029] Here, the partition plate 221 is a rectangular, approximately flat plate that is slightly larger than the abdominal surface portions 211a and 211b. The first frame portion 222 is a portion that protrudes in a rectangular frame shape from the outer edge of the partition plate 221 toward the +Y-axis side. A battery cell 21 can be fitted into the portion surrounded by the partition plate 221 and the first frame portion 222. The second frame portion 223 is a portion that protrudes in a rectangular frame shape from the outer edge of the partition plate 221 toward the -Y-axis side. A battery cell 21 can be fitted into the portion surrounded by the partition plate 221 and the second frame portion 223. That is, by disposing the first resin frame 22A between the two battery cells 21, the two battery cells 21 are stacked in a layered configuration in the thickness direction of the battery cells 21 (the direction along the Y-axis) while being electrically insulated by the partition plate 221.

[0030] 8, connecting protrusions 222a that protrude toward the +Y axis are provided at the lower corners of the first frame portion 222. Furthermore, connecting recesses 223a into which the connecting protrusions 222a fit are provided at the lower corners of the second frame portion 223, as shown in FIG. 9. That is, the multiple first resin frames 22A are configured to be connectable in a stacked manner along the Y axis by fitting the connecting protrusions 222a into the connecting recesses 223a. In this embodiment, as shown in FIGS. 5 and 6, three first resin frames 22A are used, and four battery cells 21 are stacked in a stacked manner in the thickness direction of the battery cells 21 (the direction along the Y axis).

[0031] The second resin frame 22B differs from the first resin frame 22A only in that it does not include the second frame portion 223. As shown in Figures 5 and 6, the second resin frame 22B is disposed on the -Y axis side of the battery cell 21 that is located furthest from the -Y axis side among the multiple battery cells 21 arranged in a stack.

[0032] [Case configuration] The case 3 is made of a rigid resin material and houses the battery stack 2 with the electrode terminals 212 facing the +Z axis. As shown in Figures 1 to 5, the case 3 includes a case main body 31 and a case cover 32 (Figures 1 to 4).

[0033] As shown in FIGS. 1 to 5, the case body 31 is a rectangular parallelepiped hollow member having first to fourth side wall portions 311 to 314, a bottom wall portion 315, and an upper wall portion 316.

[0034] Here, the first and second sidewalls 311, 312 are wall portions that are perpendicular to the direction along the Y axis and face each other. More specifically, the first sidewall 311 is located on the +Y axis side of the second sidewall 312.

[0035] 4, first side wall portion 311 is provided with recess 311a that is rectangular in plan view and recessed toward the -Y axis side, with part of the outer edge remaining. Also, side opening 311b that is rectangular in plan view and penetrates from the inside to the outside of case main body 31 is provided on the bottom surface of recess 311a. Side opening 311b corresponds to the opening according to the present invention.

[0036] In the second side wall portion 312, a recessed portion 312a is provided in an approximate center portion in the direction along the Z axis, recessed toward the +Y axis side and extending in the direction along the X axis, as shown in Fig. 3. Here, on the bottom surface of the recessed portion 312a, cylindrical protrusions 312b that protrude toward the -Y axis side are provided on both ends in the direction along the X axis, as shown in Fig. 5. In Fig. 5, the tip portions of the protrusions 312b before deformation are represented by dashed lines.

[0037] The third and fourth sidewalls 313, 314 are wall portions that are perpendicular to the X-axis direction and face each other. More specifically, the third sidewall 313 is located on the +X-axis side of the fourth sidewall 314.

[0038] 4, a recess 313a is provided in the approximate center of the third side wall 313 in the direction along the Z axis, the recess 313a being recessed toward the -X axis side and extending in the direction along the Y axis. The recess 313a communicates with the recesses 311a and 312a at each end in the direction along the Y axis.

[0039] 4, a recess 314a is provided in the approximate center of the fourth side wall 314 in the direction along the Z axis, the recess 314a being recessed toward the +X axis side and extending in the direction along the Y axis. The recess 314a communicates with the recesses 311a and 312a at each end in the direction along the Y axis.

[0040] The bottom wall portion 315 is a wall portion that is perpendicular to the direction along the Z axis.

[0041] The upper wall portion 316 is a wall portion that is perpendicular to the direction along the Z axis, is located on the +Z axis side of the bottom wall portion 315, and faces the bottom wall portion 315. As shown in Fig. 4, the upper wall portion 316 is provided with an upper surface opening portion 316a that is rectangular in plan view and penetrates from the inside to the outside of the case main body 31. The battery stack 2 is inserted into the case main body 31 through the upper surface opening portion 316a.

[0042] The case cover 32 is attached to the case body 31 so as to cover the top opening 316a.

[0043] [Configuration of Restraint Member] The restraining member 4 is wound around the outer surface of the case 3 in a circumferential direction (a circumferential direction centered on the Z axis) and restrains the battery stack 2 to the case 3 while applying a restraining load to the battery stack 2 inside the case 3 through the side opening 311b. In this embodiment, the restraining member 4 applies a restraining load to the battery stack 2 in the stacking direction of the multiple battery cells 21 (direction along the Y axis). As shown in FIGS. 1 to 5, the restraining member 4 includes an elastic plate 5 (FIGS. 4 and 5), a pressing lid 6, a first reinforcing plate 7 (FIGS. 3 to 5), and a restraining band 8.

[0044] The elastic plate 5 is made of an elastic material such as rubber or silicone, and is a flat plate that is rectangular in plan view and has a planar size slightly smaller than the planar size of the side opening 311b. The elastic plate 5 comes into contact with the abdominal surface 211a on the +Y-axis side of the battery cell 21 that is located closest to the +Y-axis side in the battery stack 2, via the side opening 311b.

[0045] The pressing lid 6 is disposed so as to close the side opening 311b, and abuts against the plate surface on the +Y-axis side of the elastic plate 5. As shown in FIGS. 1, 2, 4, and 5, the pressing lid 6 includes an end plate 61 and a second reinforcing plate 62.

[0046] The end plate 61 is made of a resin material having rigidity, and as shown in FIG. 5, a blocking portion 611 and a pressing portion 612 are integrally formed.

[0047] The blocking portion 611 is a generally flat plate having a rectangular shape in a plan view and having an outer size substantially identical to the inner size of the recess 311a in the case body 31, and is a portion that fits into the recess 311a. The plate surface of the blocking portion 611 on the +Y-axis side has a recess 611a recessed toward the -Y-axis side and extending in the direction along the X-axis, as shown in FIGS. 1, 2, and 4, at a substantially central portion in the direction along the Z-axis. The recess 611a communicates with the recesses 313a and 314a at both ends in the direction along the X-axis when the blocking portion 611 is fitted into the recess 311a. Furthermore, as shown in FIGS. 4 and 5, the bottom surface of the recess 611a has cylindrical protrusions 611b that protrude toward the +Y-axis side at both ends in the direction along the X-axis. In FIG. 5, the tip of the protrusion 611b before deformation is represented by a dashed line.

[0048] The pressing portion 612 is formed integrally with the plate surface on the -Y-axis side of the closing portion 611, and is a substantially flat plate that is rectangular in plan view and has an outer size slightly smaller than the inner size of the side opening 311b. With the closing portion 611 fitted in the recess 311a, the pressing portion 612 is inserted into the case main body 31 via the side opening 311b, and comes into contact with the elastic plate 5 to press the elastic plate 5.

[0049] The second reinforcing plate 62 is a flat plate having a rectangular shape in a plan view and made of a hard metal material that is more rigid than the case 3 and the end plate 61. More specifically, the second reinforcing plate 62 has an outer size slightly smaller than the inner size of the recess 611a and is disposed within the recess 611a. That is, the second reinforcing plate 62 faces the elastic plate 5 across the end plate 61. When disposed within the recess 611a, the second reinforcing plate 62 abuts against the bottom surface of the recess 611a. As shown in FIG. 4, the second reinforcing plate 62 has circular holes 621 that penetrate from the front to the back at both ends along the X-axis. When the second reinforcing plate 62 is disposed within the recess 611a, the protrusions 611b are inserted into the circular holes 621, and the tips of the protrusions 611b protrude further toward the +Y-axis side than the second reinforcing plate 62 (FIG. 5).

[0050] The first reinforcing plate 7 has the same configuration as the second reinforcing plate 62. That is, the first reinforcing plate 7 is provided with a circular hole 71 similar to the circular hole 621 of the second reinforcing plate 62 (FIG. 5). The first reinforcing plate 7 has an outer size slightly smaller than the inner size of the recess 312a, and is disposed within the recess 312a. When disposed within the recess 312a, the first reinforcing plate 7 abuts against the bottom surface of the recess 312a. When the first reinforcing plate 7 is disposed within the recess 312a, the protrusion 312b is inserted into the circular hole 71, and the tip of the protrusion 312b protrudes further toward the -Y axis than the first reinforcing plate 7 (FIG. 5).

[0051] The restraint bands 8 are made of a hard metal material with the same rigidity as the first and second reinforcing plates 7, 62. The restraint bands 8 are attached to the outer surface of the case 3 and connected to the holding lid 6, thereby restraining the battery stack 2 to the case 3 in a state in which a restraint load is applied to the battery stack 2 in the stacking direction of the plurality of battery cells 21 (the direction along the Y axis) via the holding lid 6 and the elastic plate 5. In this embodiment, the restraint bands 8 include a first restraint band 81 and a second restraint band 82, as shown in FIGS. 1 to 5 .

[0052] The first restraining band 81 connects first ends of the pressing lid 6 and the first reinforcing plate 7 that are adjacent to each other in the circumferential direction (the circumferential direction centered on the Z axis) that follows the outer surface of the case 3. The first ends are ends on the +X axis side of the pressing lid 6 and the first reinforcing plate 7. As shown in FIGS. 4 and 5, the first restraining band 81 includes a base 811 and a pair of upright pieces 812.

[0053] The base 811 is a flat plate that is rectangular in plan view and extends along the Y axis and has a width slightly smaller than the width of the recess 313a in the Z axis direction. The base 811 is disposed in the recess 313a. When disposed in the recess 313a, the base 811 abuts against the bottom surface of the recess 313a.

[0054] The pair of standing pieces 812 are flat plates that are rectangular in plan view and extend from both end edges in the Y-axis direction of the base 811, bending at approximately 90 degrees toward the -X-axis side. When the base 811 is disposed in the recess 313a, the pair of standing pieces 812 abut against the plate surface on the -Y-axis side of the first reinforcing plate 7 and the plate surface on the +Y-axis side of the second reinforcing plate 62, respectively.

[0055] 4, standing piece 812 has notch 812a cut out from the tip toward base 811. When base 811 is disposed in recess 313a, protrusions 611b and 312b are inserted into notch 812a. In this state, the tip of protrusion 611b protrudes further toward the +Y-axis side than standing piece 812 on the +Y-axis side. Similarly, the tip of protrusion 312b protrudes further toward the -Y-axis side than standing piece 812 on the -Y-axis side.

[0056] The second restraint band 82 connects the second ends of the pressing cover 6 and the first reinforcing plate 7 that are adjacent to each other in the circumferential direction (circumferential direction centered on the Z axis) that follows the outer surface of the case 3. The second ends are the ends of the pressing cover 6 and the first reinforcing plate 7 on the -X axis side. The second restraint band 82 has the same configuration as the first restraint band 81. That is, the second restraint band 82 includes a base 821 and a pair of upright pieces 822 (including notches 822a) that are similar to the base 811 and the pair of upright pieces 812 (including notches 812a) of the first restraint band 81 ( FIG. 4 ). The base 821 has a width slightly smaller than the width of the recess 314a in the Z axis direction and is disposed within the recess 314a. When disposed within the recess 314a, the base 821 abuts against the bottom surface of the recess 314a. Furthermore, when base 821 is disposed within recess 314a, the pair of upright pieces 822 abut against the plate surface of first reinforcing plate 7 on the -Y-axis side and the plate surface of second reinforcing plate 62 on the +Y-axis side, respectively. Furthermore, when base 821 is disposed within recess 314a, protrusions 611b and 312b are inserted into notch 822a. In this state, the tip of protrusion 611b protrudes further toward the +Y-axis side than upright piece 822 on the +Y-axis side. Similarly, the tip of protrusion 312b protrudes further toward the -Y-axis side than upright piece 822 on the -Y-axis side.

[0057] [How to assemble the battery pack] Next, a method for assembling the above-mentioned battery pack 1 will be described. First, the worker performs the following accommodation step. Specifically, the worker combines multiple battery cells 21 with the resin frame 22 to assemble the battery stack 2. The worker also places the battery stack 2 in the case body 31 with the electrode terminals 212 facing the +Z axis side.

[0058] Next, the worker performs the restraining step described below. Specifically, the worker inserts the elastic plate 5 into the case body 31 through the side opening 311b and assembles the end plate 61 to close the side opening 311b. The worker also assembles the first reinforcing plate 7 into the recess 312a of the case body 31 and the second reinforcing plate 62 into the recess 611a of the end plate 61. The worker then assembles the first and second restraint bands 81 and 82 to the case body 31 so that the protrusions 611b and 312b are inserted into the cutouts 812a and 822a. The worker then presses the second reinforcing plate 62 toward the -Y axis, thereby applying a restraint load to the battery stack 2 via the end plate 61 and the elastic plate 5 in the stacking direction of the multiple battery cells 21 (the direction along the Y axis), and thermally crimps the protrusions 611b and 312b to deform the tips of the protrusions 611b and 312b. This fixes the pressure cover 6, the first reinforcing plate 7, and the restraint band 8 to the case body 31, and the battery stack 2 is fixed to the case body 31 with a restraint load applied in the stacking direction of the multiple battery cells 21 (direction along the Y axis) by the elastic force of the pair of upright pieces 812, 822.

[0059] Finally, the worker performs the sealing process described below. Specifically, the worker connects electrode wiring to the electrode terminal 212 through the top opening 316a of the case main body 31, and then fixes the case cover 32 to the case main body 31 with bolts or the like to prevent water, dust, etc. from entering the inside of the battery pack 1.

[0060] According to the present embodiment described above, the following effects are achieved. The battery pack 1 according to this embodiment includes a restraining member 4 that restrains the battery stack 2 to the case body 31 while applying a restraining load to the battery stack 2 in the case body 31 in the stacking direction of the multiple battery cells 21 through the side opening 311b. That is, because the battery stack 2 is restrained to the case body 31 by the restraining members 4, welding as in the technique described in Patent Document 1 is not required, and a heat insulating member to protect the battery cells 21 from heat during welding is not required. This allows the size of the battery stack 2 to be reduced, thereby making the battery pack 1 more compact. Furthermore, by reducing the size of the battery stack 2, the mounting space within the case body 31 is expanded, allowing more battery cells 21 to be mounted within the case body 31. Therefore, if the battery pack 1 is mounted in an electric vehicle, the cruising range of the electric vehicle can be improved. Furthermore, because the battery stack 2 is restrained to the case body 31 by the restraining members 4, an adhesive for fixing the battery stack 2 to the case body 31 is not required. This eliminates the need for a process for applying the adhesive and the cost of the adhesive material, thereby reducing the cost of the battery pack 1. As described above, according to the battery pack 1 of this embodiment, the battery pack 1 can be made smaller and less expensive.

[0061] In particular, the restraint member 4 is wound around the entire circumference (circumferential direction centered on the Z axis) of the outer surface of the case member 31. This allows the pressure of the load caused by the expansion and contraction of the battery cells 21 when the battery cells 21 are charged and discharged to be dispersed.

[0062] Furthermore, in the battery pack 1 according to this embodiment, the restraining member 4 includes the elastic plate 5, the holding cover 6, the first reinforcing plate 7, and the restraining band 8 described above. That is, by employing the elastic plate 5, when a restraining load is applied to the battery stack 2 in the stacking direction of the plurality of battery cells 21, the elastic plate 5 can alleviate the load on the battery stack 2. Furthermore, the elastic plate 5 can alleviate the pressure of the load caused by the expansion and contraction of the battery cells 21 during charging and discharging. Furthermore, when the battery cells 21 expand and contract during charging and discharging, it is difficult to suppress the pressure of the load caused by the expansion and contraction of the battery cells 21 using only the case body 31 and the end plates 61. However, by employing the first and second reinforcing plates 7, 62, the pressure of the load caused by the expansion and contraction of the battery cells 21 can be suppressed using the first and second reinforcing plates 7, 62 as reinforcing members.

[0063] (Other embodiments) Although the embodiments for carrying out the present invention have been described above, the present invention should not be limited to only the above-described embodiments. The following modified examples 1 to 3 may also be adopted.

[0064] (Variation 1) 10 to 12 are diagrams illustrating a first modification of the embodiment. Specifically, Fig. 10 corresponds to Fig. 1 and is an overall perspective view of a battery pack 1A according to the first modification. Fig. 11 corresponds to Fig. 2 and is a view of the battery pack 1A as seen from the +Y axis side. Fig. 12 is a cross-sectional view taken along line XII-XII in Fig. 11. 10 to 12, the battery pack 1A according to this first modification is different from the battery pack 1 described in the above-described embodiment in the configuration and shape of the restraint band 8. Hereinafter, the restraint band 8 according to this first modification will be referred to as a restraint band 8A.

[0065] The restraint band 8A has a shape in which the first and second restraint bands 81, 82 and the first reinforcing plate 7 described in the above-described embodiment are integrated. That is, in this first modification, the first reinforcing plate 7 is not provided. One end of the restraint band 8A is connected to a first end portion of the pressure cover 6 at one end side in the circumferential direction (the circumferential direction centered on the Z-axis) that follows the outer surface of the case body 31, extends along the outer surface of the case body 31 in the circumferential direction, and the other end is connected to a second end portion of the pressure cover 6 at the other end side in the circumferential direction. The first end portion is the end portion of the pressure cover 6 on the +X-axis side. The second end portion is the end portion of the pressure cover 6 on the -X-axis side. More specifically, as shown in FIG. 12 , the restraint band 8A includes a back portion 83, a pair of side portions 84, and a pair of connecting pieces 85.

[0066] The rear surface portion 83 is a flat plate that is rectangular in plan view and extends along the X axis and has a width slightly smaller than the width of the recess 312a in the Z axis direction. The rear surface portion 83 is disposed within the recess 312a. When disposed within the recess 312a, the rear surface portion 83 abuts against the bottom surface of the recess 312a.

[0067] The pair of side surface portions 84 are flat plates that are rectangular in plan view and extend from both end edges in the X-axis direction of the back surface portion 83, bending at approximately 90 degrees toward the +Y-axis side. The pair of side surface portions 84 have widths that are slightly smaller than the widths in the Z-axis direction of the recesses 313a and 314a, and the recesses When the pair of side surface portions 84 are disposed in the recesses 313a and 314a, they come into contact with the bottom surfaces of the recesses 313a and 314a, respectively.

[0068] The pair of connecting pieces 85 are flat plates that are rectangular in plan view and extend in directions approaching each other while being bent at approximately 90° from the +Y-axis side edges of the pair of side surface portions 84. The pair of connecting pieces 85 each come into contact with the plate surface of the second reinforcing plate 62 on the +Y-axis side with the back surface portion 83 and the pair of side surface portions 84 disposed in the recesses 312a, 313a, 314a, respectively.

[0069] 10, the connecting piece 85 is provided with a pair of circular holes 851 that penetrate from the front to the back and are parallel to each other in the direction along the Z axis. In this first modified example, although not specifically shown, the circular holes 621 in the second reinforcing plate 62 are also provided at positions corresponding to the pair of circular holes 851. Furthermore, in the bottom surface of the recess 611a of the end plate 61, screw holes (not shown) are provided at positions corresponding to the pair of circular holes 851 instead of the protrusions 611b.

[0070] The method for assembling the battery pack 1A according to the first modification differs from the method for assembling the battery pack 1 described in the above embodiment in the restraint step. Specifically, in the restraining step, the worker assembles the restraint band 8A to the case body 31 in place of the first reinforcing plate 7 and the first and second restraint bands 81, 82. Then, the worker presses the second reinforcing plate 62 toward the -Y axis, thereby applying a restraint load to the battery stack 2 in the stacking direction of the multiple battery cells 21 (the direction along the Y axis) via the end plate 61 and the elastic plate 5. Then, the worker fastens bolts (not shown) to screw holes (not shown) provided in the bottom surfaces of the recesses 611a of the end plate 61 through the circular holes 851, 621. This fixes the holding lid 6 and the restraint band 8A to the case body 31, and the battery stack 2 is fixed to the case body 31 with a restraint load being applied in the stacking direction of the multiple battery cells 21 (the direction along the Y axis) by the elastic force of the pair of connection pieces 85.

[0071] According to the above-described first modification, in addition to the same effects as those of the above-described embodiment, the following effects are achieved. That is, by employing the restraint band 8A, it is possible to omit the first reinforcing plate 7 described in the above embodiment, which simplifies the assembly process of the battery pack 1, and by simplifying the assembly process and reducing the number of parts, it is possible to reduce the cost of the battery pack 1.

[0072] In the above-described embodiment, the retaining cover 6, the first reinforcing plate 7, and the restraining band 8 are fixed to the case body 31 by thermally caulking the protrusions 611b, 312b, but this is not limited to this, and a fixing structure using bolts may also be adopted, as in this modified example 1.

[0073] (Variation 2) In the above-described embodiment, the end plate 61 and the second reinforcing plate 62 may be integrally formed from a metal material. According to the second modification described above, in addition to the same effects as those of the above-described embodiment, the following effects are achieved. In other words, since the end plate 61 and the second reinforcing plate 62 can be made from a single metal member, the assembly process of the battery pack 1 can be simplified, and by simplifying the assembly process and reducing the number of parts, the cost of the battery pack 1 can be reduced.

[0074] (Variation 3) In the above-described embodiment, the restraint member 4 applies a restraint load to the battery stack 2 in the stacking direction of the multiple battery cells 21 (the direction along the Y-axis), but this is not limited thereto, and the restraint load may also be applied in another direction (for example, the direction along the X-axis). Even when the configuration of the third modified example described above is adopted, the same effects as those of the above-described embodiment are achieved. [Explanation of symbols]

[0075] 1.1A battery pack 2 Battery stack 3 cases 4 Restraining member 5 Elastic Plate 6. Presser lid 7 First reinforcement plate 8,8A restraint band 21 Battery Cells 22 Resin frame 22A First resin frame 22B Second resin frame 31 Case body 32 Case Cover 61 End plate 62 Second Reinforcement Plate 71 Round hole 81 First Restraint Band 82 Second Restraint Band 83 Back part 84 Side part 85 Connection piece 211 outer case 211a,211b Ventral part 211c,211d Side part 211e Bottom part 211f Top part 212 Electrode terminal 221 Partition board 222 First frame 222a Connecting protrusion 223 Second frame 223a Connection recess 311 first side wall portion 311a Recess 311b Side opening 312 second side wall portion 312a Recess 312b Protrusion 313 Third side wall 313a Recess 314 Fourth side wall 314a Recess 315 Bottom wall 316 Upper wall section 316a Top opening 611 Occlusion 611a Recess 611b Protrusion 612 Pressing part 621 Round hole 811,821 base 812,822 Standing piece 812a, 822a Notch 851 Round hole

Claims

1. A plurality of battery cells; a case that houses the plurality of battery cells in a stacked arrangement; a restraining member that restrains the plurality of battery cells to the case, On the side of the case, An opening is provided that penetrates the inside and outside of the case, The restraining member is a battery pack wound in a circumferential direction following the outer surface of the case, and restraining the plurality of battery cells in the case while applying a restraining load to the plurality of battery cells in the case through the opening;

2. The restraining member is The battery pack according to claim 1 , wherein the restraint load is applied in a stacking direction of the plurality of battery cells.

3. The restraining member is an elastic plate made of an elastic material and abutting against the battery cell through the opening; a pressing cover disposed to close the opening and in contact with the elastic plate; 2. The battery pack according to claim 1, further comprising: a restraint band attached to an outer surface of the case and connected to the retaining lid, thereby restraining the plurality of battery cells to the case while applying a restraint load to the plurality of battery cells via the retaining lid and the elastic plate.

4. The restraining member is a first reinforcing plate attached to an outer surface of the case; The restraining band is a first restraining band connecting first end portions of the pressing lid and the first reinforcing plate that are adjacent to each other in the circumferential direction; The battery pack according to claim 3 , further comprising a second restraining band connecting the second end portions of the pressing lid and the first reinforcing plate that are adjacent to each other in the circumferential direction.

5. The restraining band is 4. The battery pack of claim 3, wherein one end is connected to a first end of the pressure cover at one end in the circumferential direction, extends along the outer surface of the case in the circumferential direction, and the other end is connected to a second end of the pressure cover at the other end in the circumferential direction.

6. The pressing lid is an end plate made of a resin material; a second reinforcing plate made of a metal material, The end plate is abutting against the elastic plate, The second reinforcing plate includes: The battery pack according to claim 3 , wherein the end plate is sandwiched between the elastic plate and the elastic plate.

7. The pressing lid is 4. The battery pack according to claim 3, which is made of a metal material.

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