JP2018067481A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery pack capable of releasing pressure within a casing without requiring a rupture place.SOLUTION: A battery pack 1 includes: a casing H including a body part 20 provided with an opening 20a and a lid part 30 for closing the opening 20a of the body part 20; and a battery module 10 accommodated in the casing H. The lid part 30 includes: a fixed part 31 fixed to the body part 20; a rim part 32 connected to the fixed part 31 and capable of bending relative to the fixed part 31; and a recess part 33 (fragile part) provided between the fixed part 31 and the rim part 32. Viewed from above, at least part of the rim part 32 overlaps with the opening 20a. The rim part 32 is capable of bending relative to the fixed part 31 from the recess part 33 as a base point due to a pressure increase within the casing H.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a battery pack.

  Patent Document 1 describes a battery pack including a plurality of batteries and a battery case in which the plurality of batteries are accommodated. The battery case of the battery pack is provided with a pressure release unit that discharges gas to the outside when the internal pressure of the battery case increases. The pressure release unit includes an opening and a sealing plate that seals the opening. When the sealing plate is partially broken and opened, the gas in the battery case is discharged.

JP 2011-198570 A

  However, in the battery pack described above, in order to discharge the gas in the battery case (housing), the sealing plate always requires a broken portion. It is difficult to control the position of the broken portion.

  An object of one aspect of the present invention is to provide a battery pack that can release pressure in a housing without requiring a breakage point.

  A battery pack according to an aspect of the present invention includes a main body provided with an opening and a housing having a lid that closes the opening of the main body, and a battery module housed in the housing. In a plan view, including a fixing portion fixed to the main body portion, an edge portion that is continuous with the fixing portion and bendable with respect to the fixing portion, and a weak portion provided between the fixing portion and the edge portion. At least a part of the edge portion overlaps the opening, and the edge portion can be bent with respect to the fixed portion with the fragile portion as a base point due to a pressure increase in the housing.

  The lid portion of the battery pack has a fragile portion provided between the fixed portion and the edge portion. Since the fragile portion has a lower mechanical strength than the other portions, stress is concentrated on the fragile portion due to an increase in pressure in the housing, and the edge portion is bent with respect to the fixed portion with the fragile portion as a base point. As a result, the edge portion is separated from the main body portion, and the pressure in the housing can be released from the opening. Therefore, it is possible to release the pressure in the housing without requiring a broken portion.

  The weak part may be a concave part. According to this configuration, even when there is a variation in the thickness of the lid due to a manufacturing error or the like, it is possible to adjust the thickness of the fragile portion to be constant by adjusting the depth of the recess.

  The recess may have a groove shape extending continuously. According to this configuration, the edge portion is more reliably bent with the fragile portion as a base point.

  The lid may be plate-shaped, and the depth of the recess may be 50% or less of the thickness of the lid. According to this configuration, the strength of the lid can be maintained.

  The housing further includes a fastening member that fixes the lid portion to the main body portion, and the fastening member may be disposed on the fixing portion and not disposed on the edge portion. According to this configuration, since the edge portion is not fixed to the main body portion by the fastening member, the edge portion is easily bent with respect to the fixed portion.

  According to one aspect of the present invention, a battery pack is provided that can release the pressure in the housing without requiring a breakage point.

1 is a perspective view schematically showing a battery pack according to an embodiment of the present invention. It is a perspective view which shows the battery module accommodated in the battery pack shown by FIG. (A) is a top view which shows schematically the cover part shown by FIG. 1, (b) is sectional drawing along the IIIb-IIIb line | wire of (a). (A) is a perspective view schematically showing the battery pack before the edge is bent, and (b) is a perspective view schematically showing the battery pack in a state where the edge is bent. (A)-(c) It is sectional drawing shown roughly by the modification of a weak part. (A) is a top view which shows roughly the modification of the cover part shown by FIG. 3, (b) is sectional drawing along the VIb-VIb line | wire of (a). It is a top view which shows roughly the modification of the cover part shown by FIG.

  Hereinafter, various embodiments will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals. In the following drawings, an orthogonal coordinate system including an X axis, a Y axis, and a Z axis may be shown.

  FIG. 1 is a perspective view schematically showing a battery pack according to an embodiment of the present invention. The battery pack 1 shown in FIG. 1 is used as a battery of a vehicle such as an electric vehicle or a forklift. As shown in FIG. 1, the battery pack 1 includes a housing H and a plurality of battery modules 10 housed in the housing H. One battery module 10 may be accommodated in the housing H. The housing | casing H has the main-body part 20 provided with the opening 20a, and the cover part 30 which block | closes the opening 20a.

  Each battery module 10 has a plurality of battery cells 11 arranged in one direction, as shown in FIG. FIG. 2 is a perspective view showing a battery module housed in the battery pack shown in FIG. As shown in FIG. 2, each battery cell 11 is held by a battery holder 12 that forms a frame. The battery cell 11 is a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery, for example, and houses an electrode assembly (not shown) in the case. The battery cell 11 is not limited to a lithium ion secondary battery, For example, a nickel hydride secondary battery may be sufficient.

  The battery cells 11 are arranged so that terminals with different polarities are adjacent to each other, and are electrically connected by the bus bar 13 so that the battery cells 11 are in series. A pair of end plates 14 capable of restraining the battery cells 11 in the arrangement direction are provided at both ends in the arrangement direction of the battery cells 11. Each end plate 14 is provided with a bracket 15 for fixing the battery module 10 to the main body 20 or the lid 30 of the housing H. The battery module 10 is fixed to the main body 20 or the lid 30 via the bracket 15 by a fastening member such as a bolt, for example. The end plate 14 and the bracket 15 may be provided integrally.

  Next, the housing H will be described with reference to FIG. 1 again. The housing | casing H has the main-body part 20 and the cover part 30, and is exhibiting the rectangular parallelepiped shape as a whole. The main body 20 and the lid 30 are fixed to each other by a fastening member such as a bolt B, for example. The main body 20 has a rectangular bottom plate 21 and a plurality of side walls 22 a, 22 b, 22 c, 22 d that continuously extend from four sides of the bottom plate 21, and an opening 20 a is formed on the opposite side of the bottom plate 21. ing. The side walls 22a, 22b, 22c, and 22d are each rectangular plate-shaped members. The main body 20 is formed, for example, by welding side walls 22a, 22b, 22c, 22d to the edge of the bottom plate 21. The main body 20 is made of a metal material such as iron.

  A seal member 40 is disposed between the main body 20 and the lid 30. The seal member 40 has, for example, a rectangular annular shape. The seal member 40 is fixed to an end portion of the side wall 22a, 22b, 22c, 22d of the main body portion 20 facing the lid portion 30 by, for example, an adhesive. The seal member 40 is formed of a material having elasticity, and is sealed between the main body 20 and the lid 30 by being pressed by the lid 30. The seal member 40 is made of a resin material such as foam rubber, for example.

  Next, the lid 30 will be described in detail with reference to FIG. 3A is a plan view schematically showing the lid portion shown in FIG. 1, and FIG. 3B is a view showing a cross section taken along line IIIb-IIIb in FIG. 3A. is there.

  As shown in FIG. 3A, the lid portion 30 includes a fixing portion 31 fixed to the main body portion 20, an edge portion 32 connected to the fixing portion 31, and between the fixing portion 31 and the edge portion 32. And a recess 33 provided on the surface. The recessed part 33 is an example of a weak part. The cover part 30 is plate shape, for example. The fixed part 31 is located at the center of the lid part 30 in the Y-axis direction. In the present embodiment, the lid portion 30 has two edge portions 32, and each edge portion 32 is located on each end side of the fixed portion 31 in the Y-axis direction. Each edge 32 is provided so that at least a part thereof overlaps the opening 20a in plan view (XY plane). That is, each edge portion 32 is provided so that at least a portion thereof overlaps the opening 20a when the opening 20a is viewed from the front. Each edge portion 32 includes a corner portion of the lid portion 30. A recessed portion 33 is provided between the fixing portion 31 and each edge portion 32. The lid 30 may have one edge 32 or may have three or more edges 32. A bolt B for fixing the lid portion 30 to the main body portion 20 is disposed on the fixing portion 31, and no bolt B is disposed on the edge portion 32. The bolt B is an example of a fastening member. Note that the position of the boundary between the fixed portion 31 and the edge portion 32, that is, the position of the concave portion 33 is not limited to this embodiment, and may be arbitrarily set within a range where a part of the edge portion 32 overlaps the opening 20a in plan view. It can be changed.

  The concave portion 33 has a groove shape that continuously extends from one end to the other end of the lid portion 30 in the X-axis direction. More specifically, the recess 33 extends linearly so as to cross the opening 20a. Further, as shown in FIG. 3B, the cross-sectional shape of the recess 33 in the YZ plane is substantially V-shaped. The depth t of the concave portion 33 is 50% or less (half or less) of the thickness (dimension in the Z-axis direction) 30t of the lid portion 30. The depth t of the recess 33 may be 10% or more and half or less of the thickness (dimension in the Z-axis direction) 30t of the lid portion 30. The thickness 30t of the lid portion 30 can be set to 3 mm to 9 mm, and 6 mm to 8 mm, for example. The thickness 33 t of the lid 30 in the recess 33 is a value obtained by subtracting the depth t of the recess from the thickness 30 t of the lid 30. The thickness 33t of the lid portion 30 in the concave portion 33 can be, for example, not less than 0.5 mm and not more than 6 mm. For example, when the thickness 30t of the lid 30 is 8 mm, the thickness 33t of the lid 30 in the recess 33 is 4 mm or more and 5 mm or less, and when the thickness 30t of the lid 30 is 3 mm, the thickness of the lid 30 in the recess 33 is 2 mm. It is. By providing the concave portion 33 in this manner, the thickness 33t of the lid portion 30 in the concave portion 33 is more than half of the thickness 30t of the lid portion 30, so that the strength of the lid portion 30 can be maintained. The concave portion 33 can be formed, for example, by pressurizing the lid portion using a mold having a V-shaped convex portion. The recessed part 33 may be formed by cutting a cover part, and may be formed from the beginning by casting a cover part using the casting_mold | template which has a V-shaped convex part.

  4A is a perspective view schematically showing the battery pack before the edge is bent, and FIG. 4B is a perspective view schematically showing the battery pack in a state where the edge is bent. The edge portion 32 can be bent with respect to the fixed portion 31 with the recessed portion 33 as a base point by the pressure increase in the housing H. In the battery module 10 as shown in FIG. 2, gas (for example, hydrogen) may be generated in the battery cell 11 when an abnormality occurs in the battery cell 11. The battery cell 11 is provided with a pressure release mechanism (not shown) such as a safety valve, for example. When the pressure in the battery cell 11 exceeds a threshold value, the gas in the battery cell 11 is released into the housing H. . Thereby, when abnormality arises in the battery cell 11, the pressure in the housing | casing H rises. Since the concave portion 33 has a lower mechanical strength than the other portions of the lid portion 30, when the pressure in the housing H increases, stress concentrates in the concave portion 33. When the pressure in the housing H rises and exceeds the threshold value, the edge portion 32 bends with respect to the fixed portion 31 with the recess portion 33 as a base point, as shown in FIG. At this time, the recess 33 is not broken. In practice, the edge 32 is often only slightly bent, but is exaggerated in FIG. 4 for convenience of explanation.

  As described above, the lid portion 30 of the battery pack 1 according to the present embodiment has the concave portion 33 provided between the fixing portion 31 and the edge portion 32. Since the recess 33 has a lower mechanical strength than the other portions, stress is concentrated in the recess 33 due to an increase in pressure in the housing H, and the edge 32 is bent with respect to the fixed portion 31 with the recess 33 as a base point. As a result, the edge portion 32 is separated from the main body portion 20, and the pressure in the housing H can be released from the opening 20a. Therefore, it is possible to release the pressure in the housing H without requiring a broken portion. Since the edge portion 32 is deformed with the concave portion 33 as a base point, the bent portion can be controlled to a desired position by adjusting the position where the concave portion 33 is provided.

  In the battery pack 1, the lid portion 30 has a concave portion 33 as a fragile portion. As a result, even when the thickness 30t of the lid portion 30 varies due to a manufacturing error or the like, the thickness 33t of the lid portion 30 in the concave portion 33 is adjusted to be constant by adjusting the depth t of the concave portion 33. It is possible. Therefore, it is possible to stabilize the pressure at which the edge portion 32 is bent. Variation due to a manufacturing error or the like of the thickness 30t of the lid 30 is, for example, about 10% of the thickness 30t. Since the concave portion 33 has a groove shape extending continuously, the edge portion 32 is more reliably bent with the concave portion 33 as a base point.

  The depth t of the recess 33 is 50% or less of the thickness 30 t of the lid 30. Thereby, the intensity | strength of the cover part 30 can be maintained. Since it is not necessary to process the lid 30 deeply to form the recess 33, the recess 33 can be easily formed.

  In the battery pack 1, the housing H further includes a bolt B that fixes the lid portion 30 to the main body portion 20, and the bolt B is disposed at the fixing portion 31 and is not disposed at the edge portion 32. Thus, since the edge 32 is not fixed to the main body 20 by the bolt B, the edge 32 is easily bent with respect to the fixed part 31. Since the edge portion 32 is bent with the concave portion 33 as a base point, it is possible to suppress the stress on the fixing portion 31, so that the load on the bolt B can be reduced.

  As mentioned above, although embodiment of this invention has been described, the battery pack which concerns on this invention is not limited to the battery pack 1 mentioned above. In the battery pack according to the present invention, the above-described battery pack 1 can be arbitrarily modified without changing the gist of each claim.

  For example, the shape of the recessed part 33 is not limited to the above-mentioned embodiment, It can change arbitrarily. FIG. 5 is a cross-sectional view schematically showing a modification of the recess. In the above-described embodiment, the depth t of the recess 33 is equal to or less than half of the thickness 30t of the lid 30. However, the depth t of the recess 33 can be arbitrarily changed. For example, as shown in FIG. 5A, the depth t of the recess 33 may be half or more than the thickness 30 t of the lid 30. More preferably, the depth t of the recess 33 may be not less than 50% and not more than 70% of the thickness 30 t of the lid 30. According to this configuration, even when the thickness 30t of the lid portion 30 is relatively large, such as 6 mm or more, and further 9 mm or more, the edge portion 32 is fixed when the pressure in the housing H exceeds the threshold value. Bend with respect to 31.

  In the above-described embodiment, the cross-sectional shape of the concave portion 33 in the YZ plane is substantially V-shaped. However, as shown in FIG. 5B, the cross-sectional shape of the concave portion 33 in the YZ plane may be an arc shape. . As shown in FIG. 5C, the cross-sectional shape of the recess 33 in the YZ plane may be a trench having a flat bottom. In this case, the thickness 33t of the lid 30 in the recess 33 can be easily adjusted.

  In the above-mentioned embodiment, although the recessed part 33 was the groove | channel shape extended continuously, the recessed part 33 may be formed intermittently so that it may follow a straight line. FIG. 6A is a plan view schematically showing a modification of the lid shown in FIG. 3, and FIG. 6B shows a cross section taken along the line VIb-VIb in FIG. 6A. FIG. As shown in FIG. 6A, in the lid portion 30A according to the modification, the plurality of concave portions 33 are formed apart from each other along a straight line extending from one end to the other end in the X-axis direction. . The shape of each recess 33 in plan view is, for example, a circular shape. As shown in FIG. 6B, the depth t of each recess 33 is less than or equal to half the thickness 30t of the lid 30A. That is, the thickness 33t of the lid 30 in each recess 33 is more than half the thickness 30t of the lid 30. Also in this case, stress concentrates on the recess 33 due to the pressure increase in the housing H, so that the edge 32 is bent with respect to the fixed portion 31 with the straight line on which the plurality of recesses 33 are formed as a base point. Therefore, it is possible to release the pressure in the housing H without requiring a broken portion. Also in the lid portion 30A according to the modification, the shape of the recess 33 is not particularly limited. For example, the shape of each recess 33 in plan view may be rectangular. The depth t of each recess 33 may be half or more than the thickness 30t of the lid 30A.

  In the above embodiment, the fragile portion is the concave portion 33 provided in the lid portion 30, but the fragile portion only needs to have lower mechanical strength than the other portions of the lid portion 30, and may not be the concave portion 33. Good. For example, the brittle portion may be formed by partially heat-treating the lid portion 30 and locally changing the mechanical strength.

  Next, a lid 30B according to a modification of the lid 30 will be described with reference to FIG. 7 is a plan view schematically showing a modification of the lid shown in FIG. In the above embodiment, the recess 33 extends from one end to the other end of the lid 30 (for example, one end to the other end in the X-axis direction), but as shown in FIG. The lid 30B may extend from one end in the X-axis direction to one end in the Y-axis direction. More specifically, in the lid portion 30B, the concave portion 33 continuously extends from one end located on the X axis positive side of the lid portion 30B to the other end located on the Y axis negative side. Thereby, the edge part 32 is exhibiting triangular shape in planar view. Thus, the direction in which the concave portion 33 extends and the shape of the edge portion 32 are not particularly limited and can be arbitrarily changed.

  Bolts B are not arranged at two corners (one corner corresponds to the edge 32) on the X axis positive side of the lid 30B. Thus, there are cases where the bolts B cannot be evenly arranged on the lid 30B due to the arrangement and design of the components. In such a case, when the pressure in the housing H increases, the two corners may be deformed together. Therefore, as shown in FIG. 7, by providing the concave portion 33 only between one corner (edge 32) and the fixing portion 31, only one corner (edge 32) is fixed to the fixing portion 31. On the other hand, it can be bent. In other words, in the lid portion 30 </ b> B, the concave portion 33 is provided between one edge portion 32 and the fixing portion 31 among the plurality of edge portions where the bolt B is not disposed. Thereby, only the desired edge portion 32 can be bent with respect to the fixed portion 31, and unintended deformation of the lid portion 30B can be suppressed.

  The bolt B may be disposed not only at the fixing portion 31 but also at the edge portion 32.

  DESCRIPTION OF SYMBOLS 1 ... Battery pack, 10 ... Battery module, 20 ... Main-body part, 20a ... Opening, 30, 30A, 30B ... Cover part, 31 ... Fixed part, 32 ... Edge part, 33 ... Recessed part (fragile part), B ... Bolt ( Fastening member), H: casing.

Claims (5)

A housing having a main body provided with an opening and a lid for closing the opening of the main body;
A battery module housed in the housing;
With
The lid part includes a fixing part fixed to the main body part, an edge part connected to the fixing part, and a weak part provided between the fixing part and the edge part,
In plan view, at least part of the edge overlaps the opening,
The battery pack, wherein the edge portion can be bent with respect to the fixed portion with the weakened portion as a base point by an increase in pressure in the housing.   The battery pack according to claim 1, wherein the fragile portion is a concave portion.   The battery pack according to claim 2, wherein the recess has a groove shape extending continuously. The lid is plate-shaped,
The depth of the said recessed part is a battery pack of Claim 2 or 3 which is 50% or less of the thickness of the said cover part. The housing further includes a fastening member that fixes the lid to the main body.
The battery pack according to any one of claims 1 to 4, wherein the fastening member is disposed at the fixed portion and is not disposed at the edge portion.

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