Battery pack

Abstract

To disclose a technology capable of further downsizing a battery pack equipped with a fuse link plate blown out when overcurrent flows.SOLUTION: A battery pack is equipped with a fuse link plate having a bent shape. The fuse link plate is equipped with a first flat plate portion extending in a first direction, a second flat plate portion extending in a second direction, and a bending portion that connects the first flat plate portion and the second flat plate portion. The first flat plate portion, the second flat plate portion, and the bending portion are disposed along a first plane along the first direction and the second direction. The first flat plate portion is equipped with a part having a first cross-sectional are when cut by a plane orthogonal to the first direction. The second flat plate portion is equipped with a part having a second cross-sectional are when cut by a plane orthogonal to the second direction. The bending portion is equipped with a first blown-out portion having a third cross-sectional area when cut by a plane orthogonal to a direction along the first plane. The third cross-sectional area is smaller than the first cross-sectional area, and is smaller than the second cross-sectional area.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a battery pack for use in an electrical device. The battery pack includes a battery cell, a terminal electrically connected to the electrical device, and a fuse link plate electrically connecting the battery cell and the terminal. The fuse link plate includes a first flat plate portion extending in a first direction. When viewed along the first direction, the first flat plate portion includes a fusion portion having a first cross-sectional area and a non-fusion portion having a second cross-sectional area larger than the first cross-sectional area. Because the first cross-sectional area of ​​the fusion portion is smaller than the second cross-sectional area of ​​the non-fusion portion, when an overcurrent flows through the fuse link plate, the fusion portion becomes hotter than the non-fusion portion. As a result, the fuse link plate melts at the fusion portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-300315 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described battery pack, the fuse link plate has a rectangular shape extending in a first direction. Therefore, in order to accommodate the fuse link plate inside the battery pack, the battery pack becomes larger in the first direction. This specification discloses a technology that can further miniaturize a battery pack equipped with a fuse link plate that melts when an overcurrent flows. [Means for solving the problem]

[0005] The present specification discloses a battery pack for use in an electrical device. The battery pack includes a battery cell, a terminal electrically connected to the electrical device, and a fuse link plate having a bent shape and electrically connecting the battery cell and the terminal. The fuse link plate includes a first flat plate portion extending in a first direction, a second flat plate portion extending in a second direction different from the first direction, and a bent portion connecting the first flat plate portion and the second flat plate portion. The first flat plate portion, the second flat plate portion, and the bent portion are arranged along a first plane extending along both the first and second directions. The first flat plate portion includes a portion having a first cross-sectional area when cut along a plane perpendicular to the first direction. The second flat plate portion includes a portion having a second cross-sectional area when cut along a plane perpendicular to the second direction. The bent portion includes a first fusing portion having a third cross-sectional area when cut along a plane perpendicular to the first plane. The third cross-sectional area is smaller than the first cross-sectional area and smaller than the second cross-sectional area.

[0006] According to the above configuration, because the third cross-sectional area is smaller than the first cross-sectional area and smaller than the second cross-sectional area, the first fusing portion is likely to reach the highest temperature when an overcurrent flows through the fuse link plate. Therefore, the fuse link plate can be melted at the first fusing portion within the bent portion. Furthermore, according to the above configuration, the fuse link plate has a bent shape, which makes it easier to arrange the fuse link plate in the space formed inside the battery pack compared to when the fuse link plate has a rectangular shape. This prevents the battery pack from becoming larger in the first direction. According to the above configuration, a battery pack including a fuse link plate that melts when an overcurrent flows can be made smaller. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a perspective view of a battery pack 10 according to a first embodiment. [Figure 2] 1 is a perspective view of a battery pack 10 of a first embodiment with an upper casing 18 removed. [Figure 3]1 is an exploded perspective view of a plurality of battery cells 20, a first lead plate 42, a second lead plate 44, a third lead plate 46, a fourth lead plate 48, a fifth lead plate 50, and a fuse link plate 52 of the first embodiment. [Figure 4] 1 is an exploded perspective view of a plurality of battery cells 20, a first lead plate 42, a second lead plate 44, a third lead plate 46, a fourth lead plate 48, a fifth lead plate 50, and a fuse link plate 52 of the first embodiment. [Figure 5] 1 is a block diagram of a battery pack 10 and an electric device 2 according to a first embodiment. [Figure 6] FIG. 2 is a perspective view of a fuse link plate 52 according to the first embodiment. [Figure 7] FIG. 2 is a top view of a fuse link plate 52 according to the first embodiment. [Figure 8] FIG. 10 is a top view of a fuse link plate 52 according to a second embodiment. [Figure 9] FIG. 10 is a top view of a fuse link plate 52 according to a third embodiment. [Figure 10] FIG. 10 is a top view of a fuse link plate 52 according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Representative, non-limiting examples of the present invention will now be described in detail with reference to the accompanying drawings. This detailed description is intended simply to provide those skilled in the art with details for implementing preferred examples of the present invention, and is not intended to limit the scope of the present invention. Additionally, additional features and inventions disclosed below can be used separately or in conjunction with other features and inventions to provide further improved battery packs, methods of manufacturing and using the same.

[0009] Furthermore, the combinations of features and steps disclosed in the following detailed description are not essential to practicing the invention in its broadest sense, but are described solely to specifically illustrate exemplary embodiments of the invention. Furthermore, the various features of the exemplary embodiments described above and below, and those described in the independent and dependent claims, do not necessarily have to be combined in the exact embodiments described herein, or in the exact order listed, to provide additional and useful embodiments of the invention.

[0010] All features described in this specification and / or claims are intended to be disclosed individually and independently of one another as limitations on the original disclosure and claimed particulars, apart from any configuration of features described in the examples and / or claims. Furthermore, all numerical ranges and group or aggregation descriptions are intended to disclose intermediate configurations thereof as limitations on the original disclosure and claimed particulars.

[0011] In one or more embodiments, the bent portion may have a fused opening formed therein that penetrates the bent portion in a direction perpendicular to the first plane. The bent portion may include a first connecting portion disposed between the fused opening and an inner side surface of the bent portion, and a second connecting portion disposed between the fused opening and an outer side surface of the bent portion. With respect to the path length from the first flat plate portion to the second flat plate portion, the path length of the first connecting portion may be shorter than the path length of the second connecting portion. The first fused portion may be disposed in the first connecting portion.

[0012] According to the above configuration, the path length of the first connection portion is shorter than the path length of the second connection portion, and therefore the electrical resistance of the first connection portion is smaller than the electrical resistance of the second connection portion. Therefore, current flows preferentially through the first connection portion. With this configuration, when an overcurrent flows through the fuse link plate, the fuse link plate can be blown at the first fusing portion of the first connection portion.

[0013] In one or more embodiments, the second tether may include a second fusing portion having a fourth cross-sectional area when cut along a plane perpendicular to the first plane, the fourth cross-sectional area being smaller than the first cross-sectional area and smaller than the second cross-sectional area.

[0014] According to the above configuration, when the fuse link plate melts at the first fusing portion of the first connecting portion, all of the current flowing through the fuse link plate flows through the second connecting portion. Because the fourth cross-sectional area is smaller than the first cross-sectional area and also smaller than the second cross-sectional area, the second fusing portion is likely to reach the highest temperature when an overcurrent flows through the fuse link plate. This allows the fuse link plate to melt at the second fusing portion within the bent portion.

[0015] In one or more embodiments, the first flat plate portion may further include a portion having a fifth cross-sectional area larger than the first cross-sectional area when cut along a plane perpendicular to the first direction. The portion having the first cross-sectional area may constitute the first thermal diffusion prevention portion. The second flat plate portion may further include a portion having a sixth cross-sectional area larger than the second cross-sectional area when cut along a plane perpendicular to the second direction. The portion having the second cross-sectional area may constitute the second thermal diffusion prevention portion.

[0016] According to the above configuration, the first cross-sectional area is smaller than the fifth cross-sectional area. Because the first thermal diffusion prevention portion is formed on the first flat plate portion, it is possible to prevent heat from being transferred from the bent portion via the first flat plate portion. Furthermore, the second cross-sectional area is smaller than the sixth cross-sectional area. Because the second thermal diffusion prevention portion is formed on the second flat plate portion, it is possible to prevent heat from being transferred from the bent portion via the second flat plate portion. With this configuration, it is possible to prevent a decrease in the temperature of the first fusing portion, making it easier for the first fusing portion to fuse.

[0017] In one or more embodiments, the first flat plate portion may have a first thermal diffusion prevention opening formed therein, penetrating the first flat plate portion in a direction perpendicular to the first plane. The second flat plate portion may have a second thermal diffusion prevention opening formed therein, penetrating the second flat plate portion in a direction perpendicular to the first plane. The first thermal diffusion prevention portion may be disposed between the first thermal diffusion prevention opening and a side surface of the first flat plate portion. The second thermal diffusion prevention portion may be disposed between the second thermal diffusion prevention opening and a side surface of the second flat plate portion.

[0018] According to the above configuration, the first thermal diffusion prevention portion can be formed in the first flat plate portion by a simple configuration for forming the first thermal diffusion prevention opening in the first flat plate portion, and the second thermal diffusion prevention portion can be formed in the second flat plate portion by a simple configuration for forming the second thermal diffusion prevention opening in the second flat plate portion.

[0019] In one or more embodiments, the fuse link plate may be electrically connected between the negative pole of the battery cell and the terminal.

[0020] According to the above configuration, the fuse link plate can be disposed in the space formed by disposing the negative electrode and terminal of the battery cell in the battery pack, thereby preventing the battery pack from becoming large.

[0021] (First Example) A battery pack 10 of a first embodiment will be described with reference to FIGS. 1 to 7. The battery pack 10 shown in FIG. 1 is attached to a battery pack attachment portion (not shown) of an electrical device 2 (see FIG. 5) when in use. The electrical device 2 may be an electrical device that operates using power supplied from the battery pack 10. The electrical device 2 may be, for example, an electric tool using a motor 4 (see FIG. 5) as a drive source, such as a screwdriver or drill, or an electric work machine using a motor 4 (see FIG. 5) as a drive source, such as a brush cutter or blower. The electrical device 2 may also be an electrical device that does not have a motor 4, such as a light, radio, or speaker. Furthermore, the electrical device 2 may be a charger that supplies power to the battery pack 10. The rated voltage of the battery pack 10 is, for example, 18 V, and the maximum voltage of the battery pack 10 is, for example, 20 V. The rated capacity of the battery pack 10 is, for example, 2.0 Ah. In the following, the direction in which the battery pack 10 is slid when attached to the battery pack attachment portion is referred to as the rearward direction, and the direction in which the battery pack 10 is slid when removed from the battery pack attachment portion is referred to as the forward direction. Furthermore, when the battery pack 10 is attached to the battery pack attachment portion, the direction in which the battery pack attachment portion is located as viewed from the battery pack 10 is referred to as the upward direction, and the direction opposite to the upward direction is referred to as the downward direction. Furthermore, the direction perpendicular to the front-rear direction and the up-down direction is referred to as the left-right direction.

[0022] The battery pack 10 includes a casing 12 and a battery cell unit 14 (see FIG. 2) housed inside the casing 12. The casing 12 includes a lower casing 16 and an upper casing 18. The lower casing 16 and the upper casing 18 are fixed to each other by fasteners (not shown).

[0023] 2, the battery cell unit 14 includes a plurality of battery cells 20, a resin cell holder 22 that holds the plurality of battery cells 20, a control circuit board 24 that is held by the cell holder 22 on the upper side of the cell holder 22, and a plurality of battery-side terminals 26 that are provided on the upper surface of the control circuit board 24. When the battery pack 10 is attached to a battery pack attachment portion of the electric device 2, the plurality of battery-side terminals 26 mechanically engage with and electrically connect to device-side terminals (not shown) of the electric device 2.

[0024] As shown in FIGS. 3 and 4 , each of the battery cells 20 is, for example, a secondary battery cell having a substantially cylindrical shape, such as a lithium-ion battery cell. Each of the battery cells 20 has a rated capacity of, for example, 2.0 Ah, a rated voltage of, for example, 3.6 V, and a maximum voltage of, for example, 4 V. The battery cells 20 are arranged in a line in the front-rear direction with their longitudinal direction aligned with the left-right direction. In this embodiment, five battery cells 20 are arranged in a line in the front-rear direction. Hereinafter, the five battery cells 20 may be referred to as a first battery cell 30, a second battery cell 32, a third battery cell 34, a fourth battery cell 36, and a fifth battery cell 38, in that order from the front.

[0025] The battery cell unit 14 includes a first lead plate 42, a second lead plate 44, a third lead plate 46, a fourth lead plate 48, a fifth lead plate 50, and a fuse link plate 52. The first lead plate 42, the third lead plate 46, and the fifth lead plate 50 are arranged on the left side of the plurality of battery cells 20. The second lead plate 44, the fourth lead plate 48, and the fuse link plate 52 are arranged on the right side of the plurality of battery cells 20.

[0026] The first lead plate 42 includes a first cell connection portion 42a, a first lead portion 42b connected to the upper end of the first cell connection portion 42a, and a first circuit connection portion 42c connected to the first lead portion 42b. The second lead plate 44 includes a second cell connection portion 44a, a second lead portion 44b connected to the upper end of the second cell connection portion 44a, and a second circuit connection portion 44c connected to the second lead portion 44b. The third lead plate 46 includes a third cell connection portion 46a, a third lead portion 46b connected to the upper end of the third cell connection portion 46a, and a third circuit connection portion 46c connected to the third lead portion 46b. The fourth lead plate 48 includes a fourth cell connection portion 48a, a fourth lead portion 48b connected to the upper end of the fourth cell connection portion 48a, and a fourth circuit connection portion 48c connected to the fourth lead portion 48b. The fifth lead plate 50 includes a fifth cell connection portion 50a, a fifth lead portion 50b connected to the upper end of the fifth cell connection portion 50a, and a fifth circuit connection portion 50c connected to the fifth lead portion 50b. The detailed structure of the fuse link plate 52 will be described later.

[0027] The second cell connection portion 44a is spot-welded to the negative electrode 30b of the first battery cell 30 and the positive electrode 32a of the second battery cell 32. The fourth cell connection portion 48a is spot-welded to the negative electrode 34b of the third battery cell 34 and the positive electrode 36a of the fourth battery cell 36. The fuse link plate 52 is spot-welded to the negative electrode 38b of the fifth battery cell 38.

[0028] 4, the first cell connection portion 42a is spot-welded to the positive electrode 30a of the first battery cell 30. The third cell connection portion 46a is spot-welded to the negative electrode 32b of the second battery cell 32 and the positive electrode 34a of the third battery cell 34. The fifth cell connection portion 50a is spot-welded to the negative electrode 36b of the fourth battery cell 36 and the positive electrode 38a of the fifth battery cell 38.

[0029] In the battery pack 10 of this embodiment, the fuse link plate 52, the fifth battery cell 38, the fifth lead plate 50, the fourth battery cell 36, the fourth lead plate 48, the third battery cell 34, the third lead plate 46, the second battery cell 32, the second lead plate 44, the first battery cell 30, and the first lead plate 42 are electrically connected in series in this order.

[0030] As shown in FIG. 2, the first circuit connection portion 42c is inserted into a positive power supply opening 62 formed in the control circuit board 24. The second circuit connection portion 44c is inserted into a cell voltage detection opening 64 formed in the control circuit board 24. The third circuit connection portion 46c is inserted into a cell voltage detection opening 66 formed in the control circuit board 24. The fourth circuit connection portion 48c is inserted into a cell voltage detection opening 68 formed in the control circuit board 24. The fifth circuit connection portion 50c is inserted into a cell voltage detection opening 70 formed in the control circuit board 24. The fuse link plate 52 is inserted into a negative power supply opening 72 formed in the control circuit board 24.

[0031] Next, a block diagram of the battery pack 10 will be described with reference to FIG. 5 . The positive electrode of the battery cell 20 is electrically connected to the battery-side positive terminal 26a of the battery-side terminal 26 via a control circuit board 24. The negative electrode of the battery cell 20 is electrically connected to the battery-side negative terminal 26b of the battery-side terminal 26 via a fuse link plate 52 and the control circuit board 24. The control circuit board 24 controls discharge from the battery cell 20 to the battery-side positive terminal 26a and the battery-side negative terminal 26b, and discharge from the battery-side positive terminal 26a and the battery-side negative terminal 26b to the battery cell 20. When the battery pack 10 is attached to an electric device 2, the battery-side positive terminal 26a and the battery-side negative terminal 26b are electrically connected to the motor 4 via a control circuit board 6 of the electric device 2. The control circuit board 6 drives the motor 4 by controlling discharge from the battery-side positive terminal 26a and the battery-side negative terminal 26b to the motor 4. Furthermore, if the electric device 2 is a charger that includes a power supply circuit (not shown) instead of the motor 4, the battery-side positive terminal 26a and the battery-side negative terminal 26b are each electrically connected to the power supply circuit via the control circuit board 6 of the electric device 2. In this case, the control circuit board 6 charges the battery cell 20 by controlling discharge from the power supply circuit to the battery-side positive terminal 26a and the battery-side negative terminal 26b.

[0032] Next, the fuse link plate 52 will be described with reference to Figures 6 and 7. The fuse link plate 52 is made by bending a single flat plate having a uniform thickness. In a modified example, the thickness of the single flat plate may be non-uniform.

[0033] The fuse link plate 52 includes a cell connection portion 80, a lead portion 82, a first flat plate portion 84, a bent portion 86, a second flat plate portion 88, and a hemmed portion 90. As shown in FIG. 3, the cell connection portion 80 is spot-welded to the negative electrode 38b of the fifth battery cell 38. The cell connection portion 80 extends in the vertical direction. As shown in FIG. 6, the lead portion 82 extends from the upper end of the cell connection portion 80 toward the left side. The lead portion 82 is arranged along a plane (hereinafter sometimes referred to as a first plane) perpendicular to the vertical direction.

[0034] The first flat plate portion 84 extends leftward from the rear left end of the lead portion 82. When viewed from above and below, the first flat plate portion 84 has a generally rectangular shape with its longitudinal direction in the left-right direction. The width of the first flat plate portion 84 in the front-to-rear direction is constant in the left-to-right direction. Furthermore, the width of the first flat plate portion 84 in the front-to-rear direction is smaller than the width of the lead portion 82 in the front-to-rear direction. The first flat plate portion 84 is arranged along a first plane.

[0035] The bent portion 86 connects the first flat plate portion 84 and the second flat plate portion 88. The bent portion 86 extends so as to bend forward from the left end of the first flat plate portion 84. The bent portion 86 is disposed along the first plane.

[0036] The second flat plate portion 88 extends forward from the front end of the bent portion 86. The direction in which the second flat plate portion 88 extends is perpendicular to the direction in which the first flat plate portion 84 extends. When viewed in the vertical direction, the second flat plate portion 88 has a generally rectangular shape with its longitudinal direction in the front-to-rear direction. When viewed in the vertical direction, the fuse link plate 52 has a generally L-shaped overall shape, with the first flat plate portion 84, bent portion 86, and second flat plate portion 88 having a bent shape. The width of the second flat plate portion 88 in the left-to-right direction is constant in the front-to-rear direction. The width of the second flat plate portion 88 in the left-to-right direction is generally equal to the width of the first flat plate portion 84 in the front-to-rear direction. The second flat plate portion 88 is disposed along the first plane.

[0037] The hemming bent portion 90 is connected to the front end of the second flat plate portion 88. The hemming bent portion 90 is formed by bending a single flat plate so that the portions overlap. The thickness (vertical width) of the hemming bent portion 90 is approximately twice the thickness (left-right width) of the cell connection portion 80, the thickness (vertical width) of the lead portion 82, the thickness (vertical width) of the first flat plate portion 84, the thickness (vertical width) of the bent portion 86, and the thickness (vertical width) of the second flat plate portion 88. Furthermore, the cross-sectional area of ​​the hemming bent portion 90 is larger than when the hemming bent portion 90 has a thickness equivalent to the thickness of a single flat plate. This makes it possible to prevent the hemming bent portion 90 from becoming too hot when a current flows through the hemming bent portion 90.

[0038] The hemming bending portion 90 includes a first hemming bending portion 92 and a second hemming bending portion 94. The first hemming bending portion 92 extends forward from the front end of the second flat plate portion 88. The first hemming bending portion 92 is disposed along the first plane. The left-right width of the first hemming bending portion 92 is greater than the left-right width of the second flat plate portion 88. The second hemming bending portion 94 extends upward from the front end of the first hemming bending portion 92. The left-right width of the second hemming bending portion 94 is greater than the left-right width of the second flat plate portion 88.

[0039] As shown in FIG. 2 , when the fuse link plate 52 is attached to the fifth battery cell 38 and the control circuit board 24, the cell connection portion 80 is disposed in a small space formed between the negative electrode 38b of the fifth battery cell 38 and the inner surface of the lower casing 16. The cell holder 22 is disposed above the fifth battery cell 38. The lead portion 82, the first flat plate portion 84, the bent portion 86, and the second flat plate portion 88 are disposed above the cell holder 22 and below the control circuit board 24. In the up-down direction, the lead portion 82, the first flat plate portion 84, the bent portion 86, and the second flat plate portion 88 are disposed in a small space above the cell holder 22. The lead portion 82, the first flat plate portion 84, the bent portion 86, and the second flat plate portion 88 are not in direct contact with the fifth battery cell 38 due to the presence of the cell holder 22. The first hemming bent portion 92 extends from the second flat plate portion 88 toward the gap between the cell holder 22 and the control circuit board 24, and the vicinity of the front end of the first hemming bent portion 92 is disposed between the cell holder 22 and the control circuit board 24. The first hemming bent portion 92 is disposed in a minute space above the cell holder 22 and in a minute space formed between the cell holder 22 and the control circuit board 24. The second hemming bent portion 94 is inserted from the bottom to the top into the negative power supply opening 72 formed in the control circuit board 24. As described above, the fuse link plate 52 is disposed in a minute space within the battery pack 10.

[0040] As shown in FIG. 7 , a first thermal diffusion prevention opening 100 is formed in the first flat plate portion 84. The first thermal diffusion prevention opening 100 penetrates the first flat plate portion 84 in the vertical direction. When the fuse link plate 52 is viewed from the vertical direction, the first thermal diffusion prevention opening 100 has a perfect circular shape. The first thermal diffusion prevention opening 100 is disposed at a position equidistant from both the front side surface 84a and the rear side surface 84b of the first flat plate portion 84. Hereinafter, the portion where the distance between the first thermal diffusion prevention opening 100 and the front side surface 84a is smallest will be referred to as the first thermal diffusion prevention portion 102, and the portion where the distance between the first thermal diffusion prevention opening 100 and the rear side surface 84b is smallest will be referred to as the first thermal diffusion prevention portion 104. In FIG. 7 , the first thermal diffusion prevention portions 102 and 104 are each indicated by a dashed line. Furthermore, in the left-right direction, a portion of the first flat plate portion 84 where the first thermal diffusion prevention opening 100 is not arranged is referred to as the first thermal diffusion portion 106. The width W1A in the front-rear direction of the first thermal diffusion prevention portion 102 is approximately equal to the width W1B in the front-rear direction of the first thermal diffusion prevention portion 104, but is smaller than the width W1C in the front-rear direction of the first thermal diffusion portion 106. The width W1C in the front-rear direction of the first thermal diffusion portion 106 corresponds to the width in the front-rear direction of the first flat plate portion 84. The thickness (i.e., the width in the up-down direction) of the first thermal diffusion prevention portion 102 is approximately equal to the thickness (i.e., the width in the up-down direction) of the first thermal diffusion prevention portion 104, and is approximately equal to the thickness (i.e., the width in the up-down direction) of the first thermal diffusion portion 106. Therefore, when the first thermal diffusion prevention members 102, 104 and the first thermal diffusion member 106 are cut along a plane perpendicular to the left-right direction, the cross-sectional area of ​​the first thermal diffusion prevention member 102 is approximately equal to the cross-sectional area of ​​the first thermal diffusion prevention member 104 and smaller than the cross-sectional area of ​​the first thermal diffusion member 106.

[0041] A second thermal diffusion prevention opening 108 is formed in the second flat plate portion 88. The second thermal diffusion prevention opening 108 penetrates the second flat plate portion 88 in the up-down direction. When the fuse link plate 52 is viewed in the up-down direction, the second thermal diffusion prevention opening 108 has a perfect circular shape. The second thermal diffusion prevention opening 108 is disposed at a position equidistant from both the right side surface 88a and the left side surface 88b of the second flat plate portion 88. When the fuse link plate 52 is viewed in the up-down direction, the diameter of the second thermal diffusion prevention opening 108 is approximately equal to the diameter of the first thermal diffusion prevention opening 100. Hereinafter, the portion where the distance between the second thermal diffusion prevention opening 108 and the right side surface 88a is smallest will be referred to as the second thermal diffusion prevention portion 110, and the portion where the distance between the second thermal diffusion prevention opening 108 and the left side surface 88b is smallest will be referred to as the second thermal diffusion prevention portion 112. 7, the second thermal diffusion prevention portions 110, 112 are each indicated by a dashed line. Furthermore, in the front-rear direction, a portion of the second flat plate portion 88 where the second thermal diffusion prevention opening 108 is not disposed is referred to as the second thermal diffusion portion 114. The left-right width W2A of the second thermal diffusion prevention portion 110 is approximately equal to the left-right width W2B of the second thermal diffusion prevention portion 112, but is smaller than the left-right width W2C of the second thermal diffusion portion 114. The left-right width W2C of the second thermal diffusion portion 114 corresponds to the left-right width of the second flat plate portion 88. Furthermore, the left-right width W2A of the second thermal diffusion prevention portion 110 is approximately equal to the front-rear width W1A of the first thermal diffusion prevention portion 102. The thickness (i.e., width in the vertical direction) of the second thermal diffusion prevention member 110 is substantially equal to the thickness (i.e., width in the vertical direction) of the second thermal diffusion prevention member 112 and substantially equal to the thickness (i.e., width in the vertical direction) of the second thermal diffusion member 114. The thickness of the second thermal diffusion prevention member 110 is also substantially equal to the thickness of the first thermal diffusion prevention member 102. Therefore, when the second thermal diffusion prevention members 110, 112 and the second thermal diffusion member 114 are cut along a plane perpendicular to the front-to-rear direction, the cross-sectional area of ​​the second thermal diffusion prevention member 110 is substantially equal to the cross-sectional area of ​​the second thermal diffusion prevention member 112 but smaller than the cross-sectional area of ​​the second thermal diffusion member 114. The cross-sectional area of ​​the second thermal diffusion prevention member 110 is substantially equal to the cross-sectional area of ​​the first thermal diffusion prevention member 102. The cross-sectional area of ​​the second thermal diffusion member 114 is substantially equal to the cross-sectional area of ​​the first thermal diffusion member 106.

[0042] A fusion opening 116 is formed in the bent portion 86. The fusion opening 116 penetrates the bent portion 86 in the up-down direction. When the fuse link plate 52 is viewed in the up-down direction, the fusion opening 116 has a perfect circular shape. The diameter of the fusion opening 116 is larger than the diameter of the first thermal diffusion prevention opening 100 and larger than the diameter of the second thermal diffusion prevention opening 108. The width in the left-right direction between the fusion opening 116 and the first thermal diffusion prevention opening 100 is approximately equal to the width in the front-rear direction between the fusion opening 116 and the second thermal diffusion prevention opening 108. The bent portion 86 includes a first connecting portion 118 arranged between an inner side surface 86a of the bent portion 86 and the fusion opening 116, and a second connecting portion 120 arranged between an outer side surface 86b of the bent portion 86 and the fusion opening 116. The inner side surface 86a connects the front side surface 84a of the first flat plate portion 84 and the right side surface 88a of the second flat plate portion 88, and the outer side surface 86b connects the rear side surface 84b of the first flat plate portion 84 and the left side surface 88b of the second flat plate portion 88. With regard to the path length from the first flat plate portion 84 to the second flat plate portion 88 along the bent portion 86, the path length of the first connecting portion 118 is shorter than the path length of the second connecting portion 120.

[0043] Within the first connecting portion 118, a portion is formed where the distance between the inner side surface 86a and the fusion opening 116 is the shortest. Hereinafter, the portion where the distance between the inner side surface 86a and the fusion opening 116 is the shortest will be referred to as a first fusion portion 122. Furthermore, within the second connecting portion 120, two portions are formed where the distance between the outer side surface 86b and the fusion opening 116 is the shortest. Hereinafter, the portion of the portion where the distance between the outer side surface 86b and the fusion opening 116 is the shortest, and that portion is located closer to the first flat plate portion 84 in the left-right direction will be referred to as a second fusion portion 124. Also, within the portion where the distance between the outer side surface 86b and the fusion opening 116 is the shortest, that portion is located closer to the second flat plate portion 88 in the front-rear direction will be referred to as a second fusion portion 126. In FIG. 7, the first fusion portion 122 and the second fusion portions 124 and 126 are each indicated by a dashed line.

[0044] The width W3A of the first fusion portion 122 (i.e., the minimum width between the inner side surface 86a and the fusion opening 116) is greater than the width W3B of the second fusion portion 124 (i.e., the minimum width between the outer side surface 86b and the fusion opening 116), and the width W3 C (i.e., the minimum width between the outer side surface 86b and the fused opening 116). The width W3B of the second fused portion 124 is greater than the width W3 of the second fused portion 126. C The width W3A of the first fusing portion 122 is smaller than the width W1A of the first thermal diffusion prevention portion 102 in the front-rear direction and smaller than the width W2A of the second thermal diffusion prevention portion 110 in the left-right direction. The thickness (i.e., the width in the up-down direction) of the first fusing portion 122 is substantially equal to the thickness (i.e., the width in the up-down direction) of the second fusing portion 124 and is substantially equal to the thickness (i.e., the width in the up-down direction) of the second fusing portion 126. The thickness of the first fusing portion 122 is substantially equal to the thickness of the first thermal diffusion prevention portion 102 and is substantially equal to the thickness of the second thermal diffusion prevention portion 110. Therefore, when the first fusing portion 122 and the second fusing portions 124, 126 are cut along a plane perpendicular to the first plane, the cross-sectional area of ​​the first fusing portion 122 is larger than the cross-sectional area of ​​the second fusing portion 124 and is larger than the cross-sectional area of ​​the second fusing portion 126. The cross-sectional area of ​​second fusing portion 124 is approximately equal to the cross-sectional area of ​​second fusing portion 126. The cross-sectional area of ​​first fusing portion 122 is smaller than the cross-sectional area of ​​first thermal diffusion prevention portion 102 and smaller than the cross-sectional area of ​​second thermal diffusion prevention portion 110.

[0045] The width in the left-right direction between the fused opening 116 and the first thermal diffusion prevention opening 100 is smaller than the width W1C in the front-rear direction of the first thermal diffusion unit 106. In addition, the width in the front-rear direction between the fused opening 116 and the second thermal diffusion prevention opening 108 is smaller than the width W2C in the front-rear direction of the second thermal diffusion unit 114.

[0046] Next, the phenomenon of the fuse link plate 52 melting when an overcurrent flows through it will be described. In the fuse link plate 52, current flows in the following order: hemming bent portion 90, second flat portion 88, bent portion 86, first flat portion 84, lead portion 82, and cell connection portion 80. Regarding the path length of the current flowing through the bent portion 86, the path length of the first connecting portion 118 is shorter than the path length of the second connecting portion 120, so the current flows preferentially through the first connecting portion 118. The cross-sectional area of ​​the first fusing portion 122 is smaller than the cross-sectional areas of the first thermal diffusion prevention portion 102, the first thermal diffusion prevention portion 104, the second thermal diffusion prevention portion 110, and the second thermal diffusion prevention portion 112. Therefore, when an overcurrent flows through the fuse link plate 52, the first fusing portion 122 reaches the highest temperature. Furthermore, the presence of the first thermal diffusion prevention portions 102, 104 and the second thermal diffusion prevention portions 110, 112 prevents the heat from the first fusing portion 122 from being transferred via the first flat plate portion 84 or the second flat plate portion 88. This makes it easy for the first fusing portion 122 to reach a high temperature, causing the fuse link plate 52 to fuse at the first fusing portion 122.

[0047] When the fuse link plate 52 melts at the first melting portion 122, all of the current flowing through the fuse link plate 52 flows through the second connecting portion 120 within the bent portion 86. Because the cross-sectional area of ​​the second melting portions 124, 126 is smaller than the cross-sectional area of ​​the first thermal diffusion prevention portion 102, the cross-sectional area of ​​the first thermal diffusion prevention portion 104, the cross-sectional area of ​​the second thermal diffusion prevention portion 110, and the cross-sectional area of ​​the second thermal diffusion prevention portion 112, the second melting portions 124, 126 reach the highest temperature. Furthermore, the presence of the first thermal diffusion prevention portions 102, 104 and the second thermal diffusion prevention portions 110, 112 prevents the heat from the second melting portions 124, 126 from being transferred via the first flat plate portion 84 or the second flat plate portion 88. As a result, the second fusing portions 124, 126 are likely to reach high temperatures, and the fuse link plate 52 melts at least one of the second fusing portions 124, 126. This prevents current from flowing through the fuse link plate 52 from the hemming bent portion 90 to the cell connection portion 80.

[0048] (effect) In this embodiment, a battery pack 10 is used in an electrical device 2. The battery pack 10 includes a battery cell 20, a battery-side terminal 26 electrically connected to the electrical device 2, and a fuse link plate 52 having a bent shape and electrically connecting the battery cell 20 and the battery-side terminal 26. The fuse link plate 52 includes a first flat plate portion 84 extending in the left-right direction, a second flat plate portion 88 extending in a front-rear direction different from the left-right direction, and a bent portion 86 connecting the first flat plate portion 84 and the second flat plate portion 88. The first flat plate portion 84, the second flat plate portion 88, and the bent portion 86 are arranged along a first plane that extends along both the left-right direction and the front-rear direction. The first flat plate portion 84 includes first thermal diffusion prevention portions 102, 104 having specific cross-sectional areas when cut in a plane perpendicular to the left-right direction. The second flat plate portion 88 includes second thermal diffusion prevention portions 110, 112 having specific cross-sectional areas when cut in a plane perpendicular to the front-rear direction. The bent portion 86 includes a first fusing portion 122 having a specific cross-sectional area when cut along a plane perpendicular to the direction along the first plane. The cross-sectional area of ​​the first fusing portion 122 is smaller than the cross-sectional area of ​​the first thermal diffusion prevention portion 102 and also smaller than the cross-sectional area of ​​the second thermal diffusion prevention portions 110 and 112.

[0049] According to the above configuration, the cross-sectional area of ​​the first fusing portion 122 is smaller than the cross-sectional areas of the first thermal diffusion prevention portions 102, 104 and the second thermal diffusion prevention portions 110, 112. Therefore, when an overcurrent flows through the fuse link plate 52, the first fusing portion 122 is likely to reach the highest temperature. Therefore, the fuse link plate 52 can be melted at the first fusing portion 122 within the bent portion 86. Furthermore, according to the above configuration, the fuse link plate 52 has a bent shape, which makes it easier to arrange the fuse link plate 52 in the space formed inside the battery pack 10 compared to when the fuse link plate 52 has a rectangular shape. This prevents the battery pack 10 from becoming larger in the first direction (e.g., the front-rear direction). According to the above configuration, the battery pack 10 including the fuse link plate 52 that melts when an overcurrent flows can be made smaller.

[0050] Furthermore, the bent portion 86 is formed with a fused opening 116 that penetrates the bent portion 86 in a direction perpendicular to the first plane. The bent portion 86 includes a first connecting portion 118 that is disposed between the fused opening 116 and an inner side surface 86a of the bent portion 86, and a second connecting portion 120 that is disposed between the fused opening 116 and an outer side surface 86b of the bent portion 86. With respect to the path length from the first flat plate portion 84 to the second flat plate portion 88, the path length of the first connecting portion 118 is shorter than the path length of the second connecting portion 120. The first fused portion 122 is disposed in the first connecting portion 118.

[0051] According to the above configuration, the path length of the first connection portion 118 is shorter than the path length of the second connection portion 120, and therefore the electrical resistance of the first connection portion 118 is smaller than the electrical resistance of the second connection portion 120. Therefore, current flows preferentially through the first connection portion 118. With this configuration, when an overcurrent flows through the fuse link plate 52, the fuse link plate 52 can be blown out at the first fusing portion 122 of the first connection portion 118.

[0052] The second connecting part 120 also includes second fusing parts 124, 126, each having a specific cross-sectional area when cut along a plane perpendicular to the direction along the first plane. The cross-sectional area of ​​the second fusing parts 124, 126 is smaller than the cross-sectional area of ​​the first thermal diffusion part 106 and also smaller than the cross-sectional area of ​​the second thermal diffusion part 114.

[0053] According to the above configuration, when the fuse link plate 52 melts at the first melting portion 122 of the first connecting portion 118, all of the current flowing through the fuse link plate 52 flows through the second connecting portion 120. Because the cross-sectional area of ​​the second melting portions 124, 126 is smaller than the cross-sectional area of ​​the first thermal diffusion portion 106 and is also smaller than the cross-sectional area of ​​the second thermal diffusion portion 114, the second melting portions 124, 126 are likely to reach the highest temperature when an overcurrent flows through the fuse link plate 52. For this reason, the fuse link plate 52 can be melted at the second melting portions 124, 126 within the bent portion 86.

[0054] Furthermore, the first flat plate portion 84 includes a first thermal diffusion portion 106 having a specific cross-sectional area larger than the cross-sectional area of ​​the first thermal diffusion prevention portions 102, 104 when cut along a plane perpendicular to the left-right direction. The second flat plate portion 88 includes a second thermal diffusion portion 114 having a specific cross-sectional area larger than the cross-sectional area of ​​the second thermal diffusion prevention portions 110, 112 when cut along a plane perpendicular to the front-rear direction.

[0055] According to the above configuration, the cross-sectional area of ​​the first thermal diffusion prevention members 102, 104 is smaller than the cross-sectional area of ​​the first thermal diffusion member 106. Because the first thermal diffusion prevention members 102, 104 are formed on the first flat plate portion 84, it is possible to prevent heat from the bent portion 86 from being transferred via the first flat plate portion 84. Furthermore, the cross-sectional area of ​​the second thermal diffusion prevention members 110, 112 is smaller than the cross-sectional area of ​​the second thermal diffusion member 114. Because the second thermal diffusion prevention members 110, 112 are formed on the second flat plate portion 88, it is possible to prevent heat from being transferred via the second flat plate portion 88 from the bent portion 86. With this configuration, it is possible to prevent a decrease in the temperature of the first fusing member 122, making it easier for the first fusing member 122 to melt.

[0056] Furthermore, a first thermal diffusion prevention opening 100 is formed in the first flat plate portion 84, penetrating the first flat plate portion 84 in a direction perpendicular to the first plane. A second thermal diffusion prevention opening 108 is formed in the second flat plate portion 88, penetrating the second flat plate portion 88 in a direction perpendicular to the first plane. The first thermal diffusion prevention portions 102, 104 are disposed between the first thermal diffusion prevention opening 100 and the side surfaces 84a, 84b of the first flat plate portion 84. The second thermal diffusion prevention portions 110, 112 are disposed between the second thermal diffusion prevention opening 108 and the side surfaces 88a, 88b of the second flat plate portion 88.

[0057] According to the above configuration, the first thermal diffusion prevention portions 102, 104 can be formed in the first flat plate portion 84 by a simple configuration for forming the first thermal diffusion prevention opening 100 in the first flat plate portion 84. Furthermore, the second thermal diffusion prevention portions 110, 112 can be formed in the second flat plate portion 88 by a simple configuration for forming the second thermal diffusion prevention opening 108 in the second flat plate portion 88.

[0058] The fuse link plate 52 is electrically connected between the negative electrode of the battery cell 20 and the battery-side terminal 26 .

[0059] According to the above configuration, the fuse link plate 52 can be disposed in the space formed by disposing the negative electrode of the battery cell 20 and the battery-side terminal 26 inside the battery pack 10. This makes it possible to prevent the battery pack 10 from becoming large.

[0060] (Correspondence) The battery side terminal 26 is an example of a "terminal." The left-right direction is an example of a "first direction." The front-rear direction is an example of a "second direction." The cross-sectional area of ​​the first thermal diffusion prevention units 102, 104 is an example of a "first cross-sectional area." The cross-sectional area of ​​the second thermal diffusion prevention units 110, 112 is an example of a "second cross-sectional area." The cross-sectional area of ​​the first fusing unit 122 is an example of a "third cross-sectional area." The cross-sectional area of ​​the second fusing units 124, 126 is an example of a "fourth cross-sectional area." The cross-sectional area of ​​the first thermal diffusion unit 106 is an example of a "fifth cross-sectional area." The cross-sectional area of ​​the second thermal diffusion unit 114 is an example of a "sixth cross-sectional area."

[0061] (Second Example) A second embodiment will be described with reference to FIG. 8 . In the second embodiment, only differences from the first embodiment will be described. Similar components to the first embodiment are denoted by the same reference numerals and will not be described again. In the second embodiment, a notch 200 is formed in the bent portion 86 instead of the fusion opening 116 of the first embodiment. The notch 200 extends from the inner side surface 86a toward the outer side surface 86b. A first fusion portion 202 is formed between the farthest position of the notch 200 from the inner side surface 86a and the bent position 86b1 of the outer side surface 86b. The width W3A of the first fusion portion 202 is smaller than the width W1A of the first thermal diffusion prevention portion 102 of the first flat plate portion 84 in the front-to-rear direction and smaller than the width W2A of the second thermal diffusion prevention portion 110 of the second flat plate portion 88 in the left-to-right direction. Furthermore, the thickness (i.e., width in the vertical direction) of first fusing portion 202 is approximately equal to the thickness of first thermal diffusion prevention portion 102, and is approximately equal to the thickness of second thermal diffusion prevention portion 110. Therefore, when first fusing portion 202 is cut along a plane perpendicular to the first plane, the cross-sectional area of ​​first fusing portion 202 is smaller than the cross-sectional area of ​​first thermal diffusion prevention portion 102, and is smaller than the cross-sectional area of ​​second thermal diffusion prevention portion 110. When an overcurrent flows through fuse link plate 52, first fusing portion 202 reaches the highest temperature, and fuse link plate 52 is melted at first fusing portion 202.

[0062] (Third Example) A third embodiment will be described with reference to FIG. 9 . In the third embodiment, only the differences from the first embodiment will be described, and the same components as those in the first embodiment will be denoted by the same reference numerals and will not be described again. In the third embodiment, a first constricted portion 300 is formed in the first flat plate portion 84 instead of the first thermal diffusion prevention opening 100 of the first embodiment, and a second constricted portion 302 is formed in the second flat plate portion 88 instead of the second thermal diffusion prevention opening 108 of the first embodiment. The first constricted portion 300 includes a first front constricted portion 306 recessed rearward from the front side surface 84a of the first flat plate portion 84, and a first rear constricted portion 308 recessed frontward from the rear side surface 84b of the first flat plate portion 84. The tip of the first front constricted portion 306 (i.e., the portion of the first front constricted portion 306 farthest from the front side surface 84a) is not connected to the tip of the first rear constricted portion 308 (i.e., the portion of the first rear constricted portion 308 farthest from the rear side surface 84b). The width of the first flat plate portion 84 in the front-to-rear direction is smallest between the tip of the first front constricted portion 306 and the tip of the first rear constricted portion 308. Therefore, a first thermal diffusion prevention portion 310 is formed between the tip of the first front constricted portion 306 and the tip of the first rear constricted portion 308. Furthermore, in the left-right direction, the portion of the first flat plate portion 84 where the first constricted portion 300 is not located corresponds to the first thermal diffusion portion 312.

[0063] The second constricted portion 302 includes a second right constricted portion 314 recessed leftward from the right side surface 88a of the second flat plate portion 88, and a second left constricted portion 316 recessed rightward from the left side surface 88b of the second flat plate portion 88. The tip of the second right constricted portion 314 (i.e., the portion of the second right constricted portion 314 farthest from the right side surface 88a) is not connected to the tip of the second left constricted portion 316 (i.e., the portion of the second left constricted portion 316 farthest from the left side surface 88b). The left-right width of the second flat plate portion 88 is smallest between the tip of the second right constricted portion 314 and the tip of the second left constricted portion 316. Therefore, a second thermal diffusion prevention portion 318 is formed between the tip of the second right constricted portion 314 and the tip of the second left constricted portion 316. In the left-right direction, the portion of the second flat plate portion 88 where the second constricted portion 302 is not arranged corresponds to the second thermal diffusion portion 320.

[0064] The width W1A of the first thermal diffusion prevention unit 310 in the front-rear direction is smaller than the width W1C of the first thermal diffusion unit 312 in the front-rear direction. The width W1A of the first thermal diffusion prevention unit 310 in the front-rear direction is larger than the width W3A of the first fusing unit 122 and larger than the widths W3B and W3C of the second fusing units 124 and 126. The thickness (i.e., the width in the up-down direction) of the first thermal diffusion prevention unit 310 is approximately equal to the thickness (i.e., the width in the up-down direction) of the first thermal diffusion unit 312. The thickness of the first thermal diffusion prevention unit 310 is approximately equal to the thickness of the first fusing unit 122 and approximately equal to the thickness of the second fusing units 124 and 126. Therefore, when the first thermal diffusion prevention unit 310 and the first thermal diffusion unit 312 are cut along a plane perpendicular to the left-right direction, the cross-sectional area of ​​the first thermal diffusion prevention unit 310 is smaller than the cross-sectional area of ​​the first thermal diffusion unit 312. The cross-sectional area of ​​first thermal diffusion prevention part 310 is larger than the cross-sectional area of ​​first fusing part 122 and larger than the cross-sectional area of ​​second fusing parts 124 and 126 .

[0065] The width W2A in the left-right direction of the second thermal diffusion prevention member 318 is smaller than the width W2C in the left-right direction of the second thermal diffusion member 320. The width W2A in the left-right direction of the second thermal diffusion prevention member 318 is approximately equal to the width W1A in the front-rear direction of the first thermal diffusion prevention member 310. The width W2A in the left-right direction of the second thermal diffusion prevention member 318 is greater than the width W3A of the first fusing portion 122 and greater than the widths W3B and W3C of the second fusing portions 124 and 126. The thickness (i.e., the width in the up-down direction) of the second thermal diffusion prevention member 318 is approximately equal to the thickness (i.e., the width in the up-down direction) of the second thermal diffusion member 320. The thickness of the second thermal diffusion prevention member 318 is approximately equal to the thickness of the first thermal diffusion prevention member 310. The thickness of the second thermal diffusion prevention member 318 is approximately equal to the thickness of the first fusing portion 122 and the thickness of the second fusing portions 124 and 126. Therefore, when the second thermal diffusion prevention member 318 and the second thermal diffusion member 320 are cut along a plane perpendicular to the front-to-rear direction, the cross-sectional area of ​​the second thermal diffusion prevention member 318 is smaller than that of the second thermal diffusion member 320. The cross-sectional area of ​​the second thermal diffusion prevention member 318 is substantially equal to that of the first thermal diffusion prevention member 310. The cross-sectional area of ​​the second thermal diffusion prevention member 318 is larger than that of the first fusing portion 122 and larger than that of the second fusing portions 124 and 126. When an overcurrent flows through the fuse link plate 52, the first fusing portion 122 becomes the hottest, and the fuse link plate 52 melts at the first fusing portion 122. Furthermore, when the first fusing portion 122 melts, the second fusing portions 124 and 126 become the hottest, and at least one of the second fusing portions 124 and 126 melts at the fuse link plate 52.

[0066] (Fourth Example) A fourth embodiment will be described with reference to FIG. 10 . In the fourth embodiment, only the differences from the first embodiment will be described. Similar components to the first embodiment are denoted by the same reference numerals and will not be described again. In the fourth embodiment, a notch 200 is formed in the bent portion 86 instead of the fused opening 116 of the first embodiment. In the fourth embodiment, a first constricted portion 300 is formed in the first flat portion 84 instead of the first thermal diffusion prevention opening 100 of the first embodiment, and a second constricted portion 302 is formed in the second flat portion 88 instead of the second thermal diffusion prevention opening 108 of the first embodiment. The detailed configuration of the notch 200 was described in detail in the second embodiment, so a detailed description thereof will be omitted. The detailed configurations of the first constricted portion 300 and the second constricted portion 302 were described in detail in the third embodiment, so a detailed description thereof will be omitted.

[0067] The width W3A of the first fusing portion 202 of the bent portion 86 is smaller than the width W1A in the front-rear direction of the first thermal diffusion prevention portion 310 of the first flat plate portion 84, and smaller than the width W2A in the left-right direction of the second thermal diffusion prevention portion 318 of the second flat plate portion 88. The thickness of the first fusing portion 202 is substantially equal to the thickness of the first thermal diffusion prevention portion 310 and substantially equal to the thickness of the second thermal diffusion prevention portion 318. Therefore, the cross-sectional area of ​​the first fusing portion 202 is smaller than the cross-sectional area of ​​the first thermal diffusion prevention portion 310 and smaller than the cross-sectional area of ​​the second thermal diffusion prevention portion 318. When an overcurrent flows through the fuse link plate 52, the first fusing portion 202 reaches the highest temperature, and the fuse link plate 52 is melted at the first fusing portion 202.

[0068] (Variation) The fuse link plate 52 according to one embodiment may electrically connect the positive electrode of the battery cell 20 and the battery-side terminal 26 .

[0069] In one embodiment of the fuse link plate 52, when the fuse link plate 52 is viewed from above and below, the first thermal diffusion prevention opening 100, the second thermal diffusion prevention opening 108, and the fusion opening 116 may have a shape other than a perfect circle, for example, an ellipse.

[0070] In the modified examples of the second and fourth embodiments, the bending portion 86 may be formed with a second fusing portion in addition to the first fusing portion 202. In this case, the cutout portion 200 may not be connected to either the inner side surface 86a or the outer side surface 86b of the bending portion 86. The cutout portion 200 extends from a position rearward and to the left of the inner side surface 86a of the bending portion 86 to a position forward and to the right of the bending position 86b1 of the outer side surface 86b. As a result, the first fusing portion 202 is formed between the end of the cutout portion 200 on the outer side surface 86b side and the bending position 86b1 of the outer side surface 86b, and the second fusing portion is formed between the end of the cutout portion 200 on the inner side surface 86a side and the inner side surface 86a. This increases the strength of the bending portion 86. [Explanation of symbols]

[0071] 2: Electrical equipment 10: Battery pack 12: Casing 14: Battery cell unit 20: Battery cell 22: Cell holder 24: Control circuit board 26: Battery side terminal 52: Fuse link board 80: Cell connection part 82: Lead section 84: 1st flat plate part 84a: Front side 84b: Posterior side 86: Bend 86a :Inner side 86b:Outer side 88: 2nd flat plate part 88a: Right side 88b: Left side 90: Hemming bend 92: First hemming bend 94: Second hemming bend 100: First heat diffusion prevention opening 102, 104, 310: First heat diffusion prevention part 106, 312: First heat diffusion section 108: Second heat diffusion prevention opening 110, 112, 318: Second heat diffusion prevention part 114, 320: Second heat diffusion section 116: Fusing opening 118: First joint 120: Second joint 122, 202: First fusing part 124, 126: Second fusing section 200: Notch 300: First constriction 302: Second constriction

Claims

1. A battery pack for use in an electrical device, A battery cell; a terminal electrically connected to the electrical device; a fuse link plate electrically connecting the battery cell and the terminal and having a bent shape, The fuse link plate is a first flat plate portion extending in a first direction; a second flat plate portion extending in a second direction different from the first direction; a bending portion connecting the first flat plate portion and the second flat plate portion, the first flat plate portion, the second flat plate portion, and the bent portion are arranged along a first plane that is aligned with both the first direction and the second direction, a single first heat diffusion prevention opening is formed in the first flat plate portion, the first heat diffusion prevention opening penetrating the first flat plate portion in a direction perpendicular to the first plane; a single second thermal diffusion prevention opening is formed in the second flat plate portion, the second thermal diffusion prevention opening penetrating the second flat plate portion in a direction perpendicular to the first plane; a first thermal diffusion prevention portion is disposed at a portion where the distance between the first thermal diffusion prevention opening and the first side surface of the first flat plate portion is minimum, and at a portion where the distance between the first thermal diffusion prevention opening and the second side surface of the first flat plate portion is minimum, a second thermal diffusion prevention portion is disposed at a portion where the distance between the second thermal diffusion prevention opening and the first side surface of the second flat plate portion is minimum, and at a portion where the distance between the second thermal diffusion prevention opening and the second side surface of the second flat plate portion is minimum, the two first thermal diffusion prevention portions each have a first cross-sectional area when cut along a plane perpendicular to the first direction, The two second thermal diffusion prevention portions each have a second cross-sectional area when cut along a plane perpendicular to the second direction, a fused opening is formed in the bent portion, the fused opening passing through the bent portion in a direction perpendicular to the first plane; a first fusion portion is disposed in a portion where the distance between the fusion opening and the first side surface of the bent portion is smallest, the first fusing portion has a third cross-sectional area when cut along a plane perpendicular to a direction along the first plane, the third cross-sectional area is smaller than the first cross-sectional area and smaller than the second cross-sectional area; The battery pack, wherein the first cross-sectional area is equal to the second cross-sectional area.

2. A battery pack for use in an electrical device, A battery cell; a terminal electrically connected to the electrical device; a fuse link plate electrically connecting the battery cell and the terminal and having a bent shape, The fuse link plate is a first flat plate portion extending in a first direction; a second flat plate portion extending in a second direction different from the first direction; a bending portion connecting the first flat plate portion and the second flat plate portion, the first flat plate portion, the second flat plate portion, and the bent portion are arranged along a first plane that is aligned with both the first direction and the second direction, the first flat plate portion includes a first constricted portion recessed from a first side surface of the first flat plate portion and a second constricted portion recessed from a second side surface of the first flat plate portion, a first thermal diffusion prevention portion is disposed between a tip of the first constricted portion and a tip of the second constricted portion; the first thermal diffusion prevention portion has a first cross-sectional area when cut along a plane perpendicular to the first direction, the second flat plate portion includes a third constricted portion recessed from a first side surface of the second flat plate portion and a fourth constricted portion recessed from a second side surface of the second flat plate portion, a second thermal diffusion prevention portion is disposed between a tip of the third constricted portion and a tip of the fourth constricted portion; the second thermal diffusion prevention portion has a second cross-sectional area when cut along a plane perpendicular to the second direction, a fused opening is formed in the bent portion, the fused opening passing through the bent portion in a direction perpendicular to the first plane; a first fusion portion is disposed in a portion where the distance between the fusion opening and the first side surface of the bent portion is smallest, the first fusing portion has a third cross-sectional area when cut along a plane perpendicular to a direction along the first plane, the third cross-sectional area is smaller than the first cross-sectional area and smaller than the second cross-sectional area; The battery pack, wherein the first cross-sectional area is equal to the second cross-sectional area.

3. The bending portion is a first connecting portion disposed between the fused opening and an inner side surface of the bent portion corresponding to the first side surface; a second connecting portion disposed between the fused opening and the outer side surface of the bent portion, With respect to a path length from the first flat plate portion to the second flat plate portion, the path length of the first connecting portion is shorter than the path length of the second connecting portion; The battery pack according to claim 1 , wherein the first fusing portion is disposed in the first connecting portion.

4. a second fusion portion is disposed in a portion of the second connecting portion where a distance between the fusion opening and the outer side surface of the bent portion is smallest, the second fusing portion has a fourth cross-sectional area when cut along a plane perpendicular to a direction along the first plane, The battery pack of claim 3 , wherein the fourth cross-sectional area is smaller than the first cross-sectional area and smaller than the second cross-sectional area.

5. A battery pack for use in an electrical device, comprising: A battery cell; a terminal electrically connected to the electrical device; a fuse link plate electrically connecting the battery cell and the terminal and having a bent shape, The fuse link plate is a first flat plate portion extending in a first direction; a second flat plate portion extending in a second direction different from the first direction; a bending portion connecting the first flat plate portion and the second flat plate portion, the first flat plate portion, the second flat plate portion, and the bent portion are arranged along a first plane that is aligned with both the first direction and the second direction, a single first heat diffusion prevention opening is formed in the first flat plate portion, the first heat diffusion prevention opening penetrating the first flat plate portion in a direction perpendicular to the first plane; a single second thermal diffusion prevention opening is formed in the second flat plate portion, the second thermal diffusion prevention opening penetrating the second flat plate portion in a direction perpendicular to the first plane; a first thermal diffusion prevention portion is disposed at a portion where the distance between the first thermal diffusion prevention opening and the first side surface of the first flat plate portion is minimum, and at a portion where the distance between the first thermal diffusion prevention opening and the second side surface of the first flat plate portion is minimum, a second thermal diffusion prevention portion is disposed at a portion where the distance between the second thermal diffusion prevention opening and the first side surface of the second flat plate portion is minimum, and at a portion where the distance between the second thermal diffusion prevention opening and the second side surface of the second flat plate portion is minimum, the two first thermal diffusion prevention portions each have a first cross-sectional area when cut along a plane perpendicular to the first direction, The two second thermal diffusion prevention portions each have a second cross-sectional area when cut along a plane perpendicular to the second direction, a notch portion cut out from a first side surface to a second side surface of the bent portion is formed in the bent portion, a first fusing portion is disposed between the second side surface and a position of the notch portion farthest from the first side surface, the first fusing portion has a third cross-sectional area when cut along a plane perpendicular to a direction along the first plane, the third cross-sectional area is smaller than the first cross-sectional area and smaller than the second cross-sectional area; The battery pack, wherein the first cross-sectional area is equal to the second cross-sectional area.

6. A battery pack for use in an electrical device, comprising: A battery cell; a terminal electrically connected to the electrical device; a fuse link plate electrically connecting the battery cell and the terminal and having a bent shape, The fuse link plate is a first flat plate portion extending in a first direction; a second flat plate portion extending in a second direction different from the first direction; a bending portion connecting the first flat plate portion and the second flat plate portion, the first flat plate portion, the second flat plate portion, and the bent portion are arranged along a first plane that is aligned with both the first direction and the second direction, the first flat plate portion includes a first constricted portion recessed from a first side surface of the first flat plate portion and a second constricted portion recessed from a second side surface of the first flat plate portion, a first thermal diffusion prevention portion is disposed between a tip of the first constricted portion and a tip of the second constricted portion; the first thermal diffusion prevention portion has a first cross-sectional area when cut along a plane perpendicular to the first direction, the second flat plate portion includes a third constricted portion recessed from a first side surface of the second flat plate portion and a fourth constricted portion recessed from a second side surface of the second flat plate portion, a second thermal diffusion prevention portion is disposed between a tip of the third constricted portion and a tip of the fourth constricted portion; the second thermal diffusion prevention portion has a second cross-sectional area when cut along a plane perpendicular to the second direction, a notch portion cut out from a first side surface to a second side surface of the bent portion is formed in the bent portion, a first fusing portion is disposed between the second side surface and a position of the notch portion farthest from the first side surface, the first fusing portion has a third cross-sectional area when cut along a plane perpendicular to a direction along the first plane, the third cross-sectional area is smaller than the first cross-sectional area and smaller than the second cross-sectional area; The battery pack, wherein the first cross-sectional area is equal to the second cross-sectional area.

7. The battery pack according to claim 1 , wherein the fuse link plate is electrically connected between the negative electrode of the battery cell and the terminal.

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