Busbars and battery packs

Abstract

To suppress increase in the temperature of a bus bar.SOLUTION: In a battery pack in which a plurality of square batteries having positive electrode terminals and negative electrode terminals on the same plane are arranged along a first direction, the positive electrode terminals and the negative electrode terminals being arranged in a staggered manner, bus bars that connect the terminals of the same pole of the plurality of batteries to each other include a plurality of terminal connection portions to be connected to the plurality of terminals of the same pole respectively, a pair of main body portions that are connected to the plurality of terminal connection portions and formed in parallel to one another so as to extend in a first direction, and a conductive portion that conducts the pair of main body portions with each other. The bus bar further includes a heat capacity increasing portion that increases the heat capacity.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a bus bar used in a battery pack and the battery pack. [Background technology]

[0002] Conventionally, in order to increase the output of secondary batteries, battery packs in which multiple batteries are connected in parallel or series have been used. Patent Document 1 discloses the configuration of bus bars that connect multiple batteries in parallel in such battery packs. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-114540 A Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, a busbar generates heat when electricity is passed through it due to its own electrical resistance, causing the temperature to rise. Busbars through which a large current flows, such as battery packs used as power sources for electric vehicles and the like, generate a particularly large amount of heat, and so there is concern about excessive temperature rise in the busbar. Therefore, the technology of Patent Document 1 may not only deteriorate the busbar itself, but also deteriorate the connected battery, and may even cause accidents such as battery fire. For this reason, a technology capable of suppressing the temperature rise in the busbar has been desired. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] (1) According to one embodiment of the present disclosure, there is provided a busbar. The busbar is a busbar that connects terminals of the same polarity of a plurality of rectangular batteries having positive and negative terminals on the same plane in a battery pack in which the positive and negative terminals are arranged in a staggered manner, the busbar comprising: a plurality of terminal connection parts that are respectively connected to the plurality of terminals of the same polarity; a pair of main body parts that are respectively connected to the plurality of terminal connection parts and extend in the first direction and are formed in parallel to each other; and a conductive part that conducts the pair of main body parts to each other, the busbar further comprising a heat capacity increasing part that increases the heat capacity. The busbar of this embodiment further comprises a heat capacity increasing part that increases the heat capacity, and therefore the heat capacity of the busbar is increased. In addition, the increase in the surface area of ​​the busbar also acts synergistically to improve heat dissipation. This reduces the amount of heat generated when the same amount of current is passed through the busbar, as compared to a conventional configuration that does not include a heat capacity increasing portion, and makes it possible to slow down the temperature rise of the busbar and lower its maximum temperature, thereby preventing the temperature of the busbar from rising excessively when current is passed through the busbar.

[0007] (2) In the busbar of the above embodiment, the cross-sectional area of ​​the increased heat capacity portion in a cross section perpendicular to the current path of the busbar may be larger than the cross-sectional area of ​​the remaining portion of the busbar excluding the increased heat capacity portion in the cross section. In this busbar, the cross-sectional area of ​​the increased heat capacity portion in a cross section perpendicular to the current path of the busbar is larger than the cross-sectional area of ​​the remaining portion of the busbar excluding the increased heat capacity portion, thereby increasing the heat capacity of the busbar. As a result, a temperature rise of the busbar when current is passed through the busbar can be suppressed.

[0008] (3) In the busbar of the above embodiment, the heat capacity increasing portion may have a first heat capacity increasing portion that is formed in parallel with the conductive portion and connects the pair of body portions to each other. According to this embodiment, the heat capacity increasing portion has a first heat capacity increasing portion that is formed in parallel with the conductive portion and connects the pair of body portions to each other. This increases the mechanical strength of the busbar, thereby improving the vibration resistance of the busbar.

[0009] (4) In the busbar of the above embodiment, the heat capacity increasing portion may have a second heat capacity increasing portion, and the second heat capacity increasing portion may be formed at an end portion in the first direction of at least one of the pair of body portions, extending in the first direction from a position where the terminal connection portion closest to the end portion is connected to the body portion. According to this embodiment, the heat capacity increasing portion has a second heat capacity increasing portion formed at an end portion in the first direction of at least one of the pair of body portions, extending in the first direction, so that the heat capacity of the busbar is increased. Therefore, a temperature rise of the busbar when current is applied can be suppressed.

[0010] (5) In the busbar of the above embodiment, the heat capacity increasing portion may further include a third heat capacity increasing portion that is formed in parallel with the conductive portion and connects the other of the pair of body portions to the second heat capacity increasing portion. According to this embodiment of the busbar, the heat capacity increasing portion further includes a third heat capacity increasing portion that is formed in parallel with the conductive portion and connects the other of the pair of body portions to the second heat capacity increasing portion. This further increases the heat capacity. Therefore, the temperature rise of the busbar when current is applied can be further suppressed.

[0011] (6) In the busbar of the above embodiment, the increased heat capacity portion may be made of the same material as the other portions of the busbar excluding the increased heat capacity portion. In this busbar, the increased heat capacity portion is made of the same material as the other portions of the busbar excluding the increased heat capacity portion. This increases the number of current paths in the busbar, thereby reducing the current density in the busbar. This further suppresses the temperature rise in the busbar when a current is applied.

[0012] (7) According to another aspect of the present disclosure, there is provided a battery pack. The battery pack includes the bus bar of the above aspect and the plurality of batteries. According to the battery pack of this aspect, the bus bar has a heat capacity increasing portion that increases the heat capacity, so that the heat capacity of the bus bar is increased. Therefore, it is possible to suppress a temperature rise of the bus bar when a current is applied.

[0013] (8) In the battery pack of the above aspect, the busbar connects the positive terminals of the batteries to each other, and the heat capacity increasing portion may have a fourth heat capacity increasing portion, the fourth heat capacity increasing portion being formed as a part of a downstream terminal connection portion that is located most downstream in a current path of the busbar among the plurality of terminal connection portions, and the dimension of the downstream terminal connection portion along the first direction may be larger than the dimension along a short side direction of the main body portion to which the downstream terminal connection portions are connected. According to the battery pack of this aspect, in the busbar that connects the positive terminals of the batteries to each other, the fourth heat capacity increasing portion is formed as a part of a downstream terminal connection portion that is located most downstream in a current path of the busbar among the plurality of terminal connection portions. Therefore, a temperature rise of the busbar during current flow can be effectively suppressed.

[0014] (9) In the battery pack of the above aspect, the busbar connects the negative terminals of the batteries to each other, the heat capacity increasing portion has a fourth heat capacity increasing portion, the fourth heat capacity increasing portion is formed as a part of an upstream terminal connection portion that is located most upstream in a current path of the busbar among the plurality of terminal connection portions, and a dimension of the upstream terminal connection portion along the first direction may be larger than a dimension along a short side direction of the main body portion to which the upstream terminal connection portions are connected. According to the battery pack of this aspect, in the busbar that connects the negative terminals of the batteries to each other, the fourth heat capacity increasing portion is formed as a part of an upstream terminal connection portion that is located most upstream in a current path of the busbar among the plurality of terminal connection portions. Therefore, a temperature rise of the busbar during current flow can be effectively suppressed.

[0015] The present disclosure can be realized in various forms, for example, in the form of a secondary battery device equipped with a battery pack, a method for manufacturing a bus bar, a method for manufacturing a battery pack, etc. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is a perspective view showing a schematic configuration of a battery pack. [Diagram 2]FIG. 2 is a top view showing a schematic configuration of a battery pack. [Diagram 3] FIG. 1 is a perspective view showing a schematic configuration of a battery. [Figure 4] FIG. 4 is a perspective view showing a detailed configuration of a bus bar. [Diagram 5] FIG. 4 is a top view showing a detailed configuration of the bus bar. [Figure 6] FIG. 5 is a view taken along the arrow A. [Figure 7] FIG. 11 is a perspective view showing a detailed configuration of a bus bar according to a second embodiment. [Figure 8] FIG. 11 is a perspective view showing a detailed configuration of a bus bar according to a third embodiment. [Figure 9] FIG. 13 is a top view showing a detailed configuration of a bus bar according to a third embodiment. [Figure 10] FIG. 13 is a perspective view showing a detailed configuration of a bus bar according to a fourth embodiment. [Figure 11] FIG. 13 is a top view showing a detailed configuration of a bus bar according to a fourth embodiment. [Figure 12] FIG. 13 is a perspective view showing a detailed configuration of a bus bar according to a fifth embodiment. [Figure 13] FIG. 13 is a top view showing a detailed configuration of a bus bar according to a fifth embodiment. [Figure 14] FIG. 13 is an explanatory diagram showing a simulation of the maximum temperature. [Figure 15] FIG. 4 is an explanatory diagram showing a simulation of the temperature distribution in the sample 1. [Figure 16] FIG. 4 is an explanatory diagram showing a simulation of the temperature distribution in the sample 2. [Figure 17] FIG. 4 is an explanatory diagram showing a simulation of the temperature distribution in the sample 3. [Figure 18] FIG. 4 is an explanatory diagram showing a simulation of the temperature distribution in sample 4. [Figure 19] FIG. 13 is an explanatory diagram showing a simulation of the current density distribution of sample 2. [Figure 20] FIG. 11 is an explanatory diagram showing a simulation of a current density distribution around a downstream terminal connection portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A. First embodiment: FIG. 1 is a perspective view showing a schematic configuration of a battery pack 100 including a bus bar 20 according to an embodiment of the present disclosure. FIG. 2 is a top view showing a schematic configuration of the battery pack 100. A plurality of battery packs 100 are arranged side by side to be modularized as described later, and constitute a part of a secondary battery device (not shown). In this embodiment, the secondary battery device is mounted on an electric vehicle (not shown), but may be mounted on any mobile body or stationary power source that uses electricity as a power source, not limited to electric vehicles. The battery pack 100 includes a plurality of rectangular batteries 10 and two bus bars 20. In addition, in FIG. 1 and FIG. 2, two conductive members 90 (described later) are illustrated together with the battery pack 100.

[0018] 3 is a perspective view showing a schematic configuration of the battery 10. The battery 10 of this embodiment is configured to include a lithium ion battery, but is not limited to a lithium ion battery and may be configured to include any type of secondary battery such as a nickel-metal hydride battery. The battery 10 has a battery main body 12, two negative electrode terminals 14, and two positive electrode terminals 16. That is, the battery 10 of this embodiment is formed by connecting two unit batteries each having one negative electrode terminal 14 and one positive electrode terminal 16.

[0019] The battery body 12 has a flat, approximately rectangular parallelepiped exterior shape. The negative terminal 14 and the positive terminal 16 are formed on the upper surface 13 of the battery body 12, protruding upward. That is, the negative terminal 14 and the positive terminal 16 are arranged on the same plane. The negative terminal 14 and the positive terminal 16 are each formed with a female screw (not shown). In the following description, in a plane parallel to the upper surface 13 of the battery body 12, the short side direction of the battery 10 is also referred to as a first direction D1, and the long side direction of the battery 10, i.e., the direction perpendicular to the first direction D1, is also referred to as a second direction D2. The two unit batteries constituting the battery 10 are connected by swapping the arrangement of the negative terminal 14 and the positive terminal 16 in the second direction D2. Thus, in the battery 10, the negative terminal 14 and the positive terminal 16 are formed side by side along the second direction D2, and the negative terminal 14 and the positive terminal 16 are formed side by side along the first direction D1. Further, on the upper surface 13 of the battery body 12, measuring terminals 18 are formed between the negative electrode terminal 14 and the positive electrode terminal 16 which are formed side by side along the second direction D2. Each measuring terminal 18 is used when measuring an intermediate potential.

[0020] As shown in FIG. 1 and FIG. 2, in the battery pack 100 of this embodiment, three batteries 10 are arranged along the first direction D1, and the negative electrode terminals 14 and the positive electrode terminals 16 are arranged in a staggered manner. Therefore, in the battery pack 100, the negative electrode terminals 14 and the positive electrode terminals 16 are arranged alternately along the first direction D1. To describe the staggered arrangement in detail, at one end side (lower side in FIG. 2) of the second direction D2, the positive electrode terminal 16 is arranged at the most one end side (left side in FIG. 2) of the first direction D1, and the positive electrode terminals 16 and the negative electrode terminals 14 are arranged alternately toward the other end side (right side in FIG. 2) of the first direction D1. On the other hand, at the other end side (upper side in FIG. 2) of the second direction D2, the negative electrode terminal 14 is arranged at the most one end side (left side in FIG. 2) of the first direction D1, and the positive electrode terminals 16 and the negative electrode terminals 14 are arranged alternately toward the other end side (right side in FIG. 2) of the first direction D1. The number of batteries 10 included in the battery pack 100 is not limited to three, and may be any number such as two or four. The battery pack 100 is modularized by arranging a plurality of batteries 100 along the first direction D1. For convenience of illustration, only one battery pack 100 is shown in Figs. 1 and 2.

[0021] The conductive member 90 has an external shape of a generally rectangular plate in a plan view with the first direction D1 as a longitudinal direction, and electrically connects adjacent battery packs 100 in series in the first direction D1. More specifically, the conductive member 90 connects the negative electrode terminal 14 of a certain battery pack 100 to the positive electrode terminal 16 of the battery pack 100 adjacent to the battery pack 100. The conductive member 90 has two through holes 92 formed side by side along the first direction D1, each penetrating the plate thickness direction. The through holes 92 are used to connect the conductive member 90 to the negative electrode terminal 14 and the positive electrode terminal 16, as described below.

[0022] Each of the two bus bars 20 has a substantially plate-like external shape and electrically connects three batteries 10 included in the battery pack 100 in parallel. One of the two bus bars 20 connects the negative electrode terminals 14 of the batteries 10 to each other, and the other of the two bus bars 20 connects the positive electrode terminals 16 of the batteries 10 to each other. That is, each bus bar 20 connects the terminals of the same polarity of the batteries 10 to each other. As described below, each bus bar 20 is assembled on the negative electrode terminals 14 or the positive electrode terminals 16 of the batteries 10. The bus bar 20 (hereinafter also referred to as the negative electrode bus bar 24) that connects the negative electrode terminals 14 of the batteries 10 to each other and the bus bar 20 (hereinafter also referred to as the positive electrode bus bar 26) that connects the positive electrode terminals 16 of the batteries 10 to each other have the same configuration and are assembled opposite to each other in a state of being inverted in the plate thickness direction. In the following description, a case where the bus bar 20 is the positive electrode bus bar 26 will be described as a representative example.

[0023] Fig. 4 is a perspective view showing a detailed configuration of busbar 20. Fig. 5 is a top view showing a detailed configuration of busbar 20. Fig. 6 is a view seen from the arrow A in Fig. 5. Busbar 20 has a plurality of terminal connection portions 40, a pair of main body portions 50, a conductive portion 60, and a heat capacity increasing portion 70.

[0024] The terminal connection parts 40 are each connected to the positive terminals 16 of the batteries 10. As described above, the battery pack 100 of this embodiment includes three batteries 10, and each battery 10 has two positive terminals 16. Therefore, the busbar 20 of this embodiment includes six terminal connection parts 40. In other words, the busbar 20 of this embodiment includes three terminal connection parts 40 arranged along the first direction D1, and the busbar 20 connects three batteries 10. Each terminal connection part 40 is formed along a plane along the first direction D1 and the second direction D2, that is, along a plane parallel to the top surface 13 of the batteries 10.

[0025] The pair of body parts 50 are formed parallel to each other, extending in the first direction D1. In the following description, one of the pair of body parts 50 is also referred to as the first body part 51, and the other of the pair of body parts 50 is also referred to as the second body part 52. That is, the first body part 51 and the second body part 52 are each connected to the three terminal connection parts 40 arranged along the first direction D1. In other words, the first body part 51 and the second body part 52 are each formed in a straight line connecting the most distant terminal connection parts 40 among the three terminal connection parts 40 arranged along the first direction D1. In this embodiment, the dimensions of the first body part 51 and the second body part 52 along the first direction D1 are equal to each other.

[0026] The terminal connection parts 40 are formed so as to protrude from one of the pair of main body parts 50 in a direction away from the other of the pair of main body parts 50 along the second direction D2. More specifically, the three terminal connection parts 40 connected to the first main body part 51 are formed so as to protrude from the second main body part 52 in the second direction D2, and the three terminal connection parts 40 connected to the second main body part 52 are formed so as to protrude from the first main body part 51 in the second direction D2. Each terminal connection part 40 has a through hole 42 penetrating in the plate thickness direction. Each through hole 42 is used for connecting the bus bar 20 and the positive electrode terminal 16, as described later. In the following description, the terminal connection part 40 located at the most downstream side in the current path of the bus bar 20 as the positive electrode bus bar 26 among the multiple terminal connection parts 40 of the bus bar 20 is also referred to as a downstream terminal connection part 44.

[0027] The direction of current flow is reversed in the negative busbar 24. For this reason, in the negative busbar 24, the terminal connection portion 40 that functioned as the downstream terminal connection portion 44 in the positive busbar 26 functions as the upstream terminal connection portion 45 located most upstream in the current path of the busbar 20. The downstream terminal connection portion 44 of the positive busbar 26 and the upstream terminal connection portion 45 of the negative busbar 24 are connected to each other by the conductive member 90, so that the assembled batteries 100 adjacent to each other in the first direction D1 are electrically connected in series.

[0028] In the following description, the terminal connection portion 40 located in a point-symmetrical position with respect to the downstream terminal connection portion 44 is also referred to as a symmetrical terminal connection portion 48. In this embodiment, the "point-symmetrical position" refers to a point-symmetrical position with respect to the center of gravity of the busbar 20 as the center point on a plane along the first direction D1 and the second direction D2.

[0029] The pair of main body portions 50 are formed along a plane parallel to the formation surface of the terminal connection portion 40. The pair of main body portions 50 and each terminal connection portion 40 are connected via a bent portion 46. The bent portion 46 is formed along a direction approximately perpendicular to each of the first direction D1 and the second direction D2. In this embodiment, the dimension of the bent portion 46 along the first direction D1 is approximately equal to the dimension of the terminal connection portion 40 along the first direction D1.

[0030] The conductive portion 60 electrically connects the pair of body portions 50 to each other. The conductive portion 60 is formed on the same plane as the pair of body portions 50 and along the second direction D2.

[0031] The heat capacity increasing portion 70 has a function of increasing the heat capacity of the busbar 20. The heat capacity increasing portion 70 of this embodiment is formed in parallel with the conductive portion 60 on the same plane as the pair of main body portions 50, and connects the pair of main body portions 50 to each other. The heat capacity increasing portion 70 of this embodiment is formed in parallel with the conductive portion 60. The heat capacity increasing portion 70 increases the volume of the busbar 20 to increase the heat capacity, thereby suppressing a temperature rise of the busbar 20 when electricity is applied. The heat capacity increasing portion also increases the surface area of ​​the busbar 20 to promote heat dissipation of the busbar 20 when electricity is applied, thereby suppressing a temperature rise of the busbar 20. Here, the pair of main body portions 50 are conductive if there is at least one bridge portion connecting them. Therefore, when there are two or more bridge portions, (n-1) of the n bridge portions correspond to the heat capacity increasing portion 70.

[0032] The busbar 20 and the conductive member 90 of this embodiment are formed by punching and bending using a copper plate as a material. Therefore, the heat capacity increasing portion 70 is integrally formed with the other portions of the busbar 20 except for the heat capacity increasing portion 70 by the same material. Therefore, the heat capacity increasing portion 70 of this embodiment makes the pair of main body portions 50 conductive to each other, similar to the conductive portion 60. Therefore, the heat capacity increasing portion 70 also functions as a conductive portion. Therefore, the heat capacity increasing portion 70 increases the current path of the busbar 20, so that the current passing between the pair of main body portions 50 of the busbar 20 during current flow is dispersed, and the current density in the conductive portion 60 and the heat capacity increasing portion 70 is reduced. In this embodiment, the dimension of the heat capacity increasing portion 70 in the first direction D1 is approximately the same as the dimension of the conductive portion 60 in the first direction D1 and the dimension of the main body portion 50 in the second direction D2. Moreover, the busbar 20 of this embodiment is formed to have an approximately constant thickness.

[0033] The negative busbar 24 and the positive busbar 26 shown in Figs. 1 and 2 have the same configuration as described above, and are assembled facing each other with the plates inverted in the plate thickness direction. The terminal connection portion 40 of the negative busbar 24 and the terminal connection portion 40 of the positive busbar 26 are assembled to be located on the same plane. Therefore, the main body portion 50 of the negative busbar 24 is located below the terminal connection portion 40, and the main body portion 50 of the positive busbar 26 is located above the terminal connection portion 40. With this configuration, the negative busbar 24 and the positive busbar 26 are insulated from each other without contacting each other. Furthermore, when viewed from above, at least a portion of each main body portion 50 overlaps.

[0034] When assembling the battery pack 100, the negative busbar 24 is placed on the negative terminal 14 of the three batteries 10, and the positive busbar 26 is placed on the positive terminal 16. Then, the conductive member 90 is placed across the downstream terminal connection portion 44 located on the most downstream side in the current path of the positive busbar 26 and the upstream terminal connection portion 45 located on the most upstream side in the current path of the negative busbar 24. At this time, each busbar 20 and the conductive member 90 are placed at a position where the through hole 42 formed in each busbar 20 and the through hole 92 formed in the conductive member 90 correspond to the female threads formed in the negative terminal 14 and the positive terminal 16, respectively. Then, bolts (not shown) are inserted into the through holes 42, 92, and the male threads of the bolts are screwed into the female threads of each terminal 14, 16 to fasten them together, thereby fixing and electrically connecting each busbar 20 and the conductive member 90 to each terminal 14, 16. The bus bars 20 and the conductive members 90 may be electrically connected to the terminals 14, 16 by any method such as welding, not limited to fastening with bolts.

[0035] In this embodiment, when viewed from the top-bottom direction, the conductive portion 60 of the negative busbar 24 and the heat capacity increasing portion 70 of the positive busbar 26 are overlapped with each other, and the heat capacity increasing portion 70 of the negative busbar 24 and the conductive portion 60 of the positive busbar 26 are overlapped with each other and assembled. Each conductive portion 60 and each heat capacity increasing portion 70 are located in the first direction D1 between the negative terminal 14 and the positive terminal 16 adjacent to each other along the first direction D1. Note that each conductive portion 60 and each heat capacity increasing portion 70 do not have to be located in the first direction D1 between the negative terminal 14 and the positive terminal 16 adjacent to each other along the first direction D1. Also, each main body portion 50 is located in the second direction D2 between the terminals 14, 16 formed on each battery 10 and the measurement terminal 18.

[0036] In this embodiment, the heat capacity increasing section 70 corresponds to the heat capacity increasing section and the first heat capacity increasing section in this disclosure.

[0037] According to the busbar 20 of the first embodiment described above, since the busbar 20 includes the heat capacity increasing portion 70 that increases the heat capacity, the heat capacity of the busbar 20 is increased. Furthermore, the increase in the surface area of ​​the busbar 20 synergistically improves the heat dissipation. As a result, compared to a conventional configuration not including the heat capacity increasing portion 70, the amount of heat generated when the same level of current is passed through the busbar 20 can be reduced, and the temperature rise of the busbar 20 can be made gentler and the maximum temperature can be reduced. Therefore, the temperature rise of the busbar 20 during current passage can be suppressed. As a result, deterioration of the busbar 20 and the battery 10 caused by the temperature rise of the busbar 20 can be suppressed.

[0038] Furthermore, since the heat capacity increasing portion 70 is formed in parallel with the conductive portion 60 and connects the pair of main body portions 50 to each other, the mechanical strength of the bus bar 20 can be increased, resulting in improved vibration resistance.

[0039] In addition, since the heat capacity increasing portion 70 is made of a conductive material and connects the pair of main body portions 50 to each other, it is possible to increase the number of current paths in the bus bar 20, thereby reducing the current density in the bus bar 20. This makes it possible to further suppress the temperature rise during current flow.

[0040] Furthermore, the pair of main body portions 50 and each terminal connection portion 40 are connected via bent portions 46 formed along directions approximately perpendicular to the second direction D2 and the first direction D1, respectively. Therefore, when the negative electrode bus bar 24 and the positive electrode bus bar 26 are inverted in the plate thickness direction and assembled to the battery 10, the negative electrode bus bar 24 and the positive electrode bus bar 26 can be prevented from coming into contact with each other, thereby preventing the occurrence of a short circuit.

[0041] Moreover, the pair of main body portions 50 are each connected to three terminal connection portions 40. That is, the bus bar 20 has three terminal connection portions 40 arranged side by side along the first direction D1, and the bus bar 20 connects three batteries 10 in parallel. For this reason, the bus bar 20 of this embodiment tends to have a large current flow and a temperature rise compared to a bus bar that connects two batteries 10 in parallel, that is, a configuration in which a pair of main body portions 50 are each connected to two terminal connection portions 40. However, the bus bar 20 of this embodiment includes the heat capacity increasing portion 70, and therefore can suppress an excessive rise in temperature of the bus bar 20 due to electrical resistance when electricity is applied.

[0042] B. Second embodiment: 7 is a perspective view showing a detailed configuration of a busbar 20a according to the second embodiment. The busbar 20a according to the second embodiment differs from the busbar 20 according to the first embodiment in that it has a heat capacity increasing portion 70a instead of the heat capacity increasing portion 70. Since the other configurations are the same as those of the busbar 20 according to the first embodiment, the same configurations are denoted by the same reference numerals and detailed description thereof will be omitted.

[0043] The heat capacity increasing portion 70a is formed to be thicker than the heat capacity increasing portion 70 of the first embodiment. Therefore, in a cross section perpendicular to the current path of the busbar 20a, more specifically, in a cross section perpendicular to the extension direction of the heat capacity increasing portion 70a, the cross-sectional area of ​​the heat capacity increasing portion 70a is larger than the cross-sectional area of ​​the conductive portion 60 and the cross-sectional area of ​​the main body portion 50. That is, the cross-sectional area of ​​the heat capacity increasing portion 70a in a cross section perpendicular to the current path of the busbar 20a is larger than the cross-sectional area of ​​the other portions of the busbar 20a except for the heat capacity increasing portion 70a. Note that, instead of or in addition to being formed to be thicker than the heat capacity increasing portion 70a of the first embodiment, the heat capacity increasing portion 70a may be formed to have a larger dimension along the first direction D1.

[0044] The busbar 20a of the second embodiment described above provides the same effects as those of the first embodiment. In addition, the cross-sectional area of ​​the heat capacity increasing portion 70a in a cross section perpendicular to the current path of the busbar 20a is larger than the cross-sectional area of ​​the other portions of the busbar 20a excluding the heat capacity increasing portion 70a, so that the heat capacity can be further increased, and as a result, the temperature rise of the busbar 20a during current flow can be further suppressed.

[0045] C. Third embodiment: FIG. 8 is a perspective view showing a detailed configuration of a busbar 20b of the third embodiment. FIG. 9 is a top view showing a detailed configuration of a busbar 20b of the third embodiment. The busbar 20b of the third embodiment is different from the busbar 20 of the first embodiment in that it further has two heat capacity increasing portions 70b in addition to the heat capacity increasing portion 70. Since the other configurations are the same as those of the busbar 20 of the first embodiment, the same reference numerals are used for the same configurations, and detailed descriptions thereof are omitted. In the following description, the heat capacity increasing portion 70 of the first embodiment is also referred to as a first heat capacity increasing portion 71. For convenience of description, the busbar 20b of this embodiment is a positive electrode busbar 26. However, it is of course possible to use the busbar 20b as a negative electrode busbar 24. In the case of using the negative electrode busbar 24, the direction of current flow is reversed, so that the downstream terminal connection portion 44 functions as the upstream terminal connection portion 45.

[0046] The two heat capacity increasing portions 70b are formed on both ends of the bus bar 20b in the first direction D1. Each heat capacity increasing portion 70b has a second heat capacity increasing portion 72b and a third heat capacity increasing portion 73b.

[0047] The second heat capacity increasing portion 72b is formed at the end portion in the first direction D1 of the pair of main body portions 50, extending in the first direction D1 from the position where the terminal connection portion 40 closest to the end portion is connected to the main body portion 50. The second heat capacity increasing portion 72b connected to the first main body portion 51 is formed extending in the first direction D1 to the end portion of the second main body portion 52. The second heat capacity increasing portion 72b connected to the second main body portion 52 is formed extending in the first direction D1 to the end portion of the first main body portion 51. Therefore, when viewed from the second direction D2, the first main body portion 51 and the second heat capacity increasing portion 72b connected to the second main body portion 52 overlap each other, and the second main body portion 52 and the second heat capacity increasing portion 72b connected to the first main body portion 51 overlap each other. In this embodiment, the dimensions along the first direction D1 of the second heat capacity increasing portion 72b connected to the first main body portion 51 and the second heat capacity increasing portion 72b connected to the second main body portion 52 are equal to each other.

[0048] The third heat capacity increasing portion 73b is formed in parallel with the conductive portion 60 at the end of the pair of main body portions 50 in the first direction D1 opposite to the side where the second heat capacity increasing portion 72b is formed. One of the third heat capacity increasing portions 73b connects the first main body portion 51 to the end of the second heat capacity increasing portion 72b connected to the second main body portion 52, and the other of the third heat capacity increasing portions 73b connects the second main body portion 52 to the end of the second heat capacity increasing portion 72b connected to the first main body portion 51. That is, the third heat capacity increasing portion 73b connects the second heat capacity increasing portion 72b formed on one of the pair of main body portions 50 to the other main body portion 50 of the pair of main body portions 50. In this embodiment, the second heat capacity increasing portion 72b and the third heat capacity increasing portion 73b are connected to each other via an R-shape.

[0049] In this embodiment, the downstream terminal connection portion 44 located most downstream in the current path of the bus bar 20b serving as the positive bus bar 26 and the third heat capacity increasing portion 73b overlap with each other in the first direction D1. That is, the downstream terminal connection portion 44 and the third heat capacity increasing portion 73b are formed on the same straight line along the second direction D2.

[0050] In this embodiment, the dimension L1 of the main body 50 along the second direction D2, the dimension L2 of the conductive portion 60 along the first direction D1, the dimension L3 of the first heat capacity increasing portion 71 along the first direction D1, the dimension L4 of the second heat capacity increasing portion 72b along the second direction D2, and the dimension L5 of the third heat capacity increasing portion 73b along the first direction D1 are all substantially the same. In addition, the heat capacity increasing portion 70b in this embodiment is made of a conductive material, and therefore also functions as a conductive portion.

[0051] In this embodiment, the busbar 20b has a point-symmetric shape. In the busbar 20b, the third heat capacity portion 73b and the second heat capacity portion 72b connected to the downstream terminal connection portion 44 and the third heat capacity portion 73b and the second heat capacity portion 72b connected to the symmetric terminal connection portion 48 are located at point-symmetric positions. Note that, in this embodiment, "point-symmetric positions" refers to point-symmetric positions with respect to the center of gravity of the busbar 20b as the center point on a plane along the first direction D1 and the second direction D2.

[0052] The busbar 20b of the third embodiment described above provides the same effects as those of the first embodiment. In addition, the busbar 20b includes the heat capacity increasing portion 70b having the second heat capacity increasing portion 72b and the third heat capacity increasing portion 73b, so that the heat capacity can be further increased. Therefore, the temperature rise of the busbar 20b during current flow can be further suppressed.

[0053] In addition, the second heat capacity increasing portion 72b and the third heat capacity increasing portion 73b are both made of a conductive material and therefore also function as a conducting portion. This allows the number of current paths in the bus bar 20b to be further increased, further reducing the current density in the bus bar 20b. This further suppresses the temperature rise in the bus bar 20b when current is applied.

[0054] In addition, the downstream terminal connection portion 44 and the third heat capacity increasing portion 73b are formed on the same straight line along the second direction D2. Therefore, compared to a configuration in which the main body portion 50 and the third heat capacity increasing portion 73b are connected at a position separated from the downstream terminal connection portion 44 in the first direction D1, the distance through which the combined current flows, that is, the current flowing through the main body portion 50 to the downstream terminal connection portion 44 and the current flowing through the third heat capacity increasing portion 73b to the downstream terminal connection portion 44, can be shortened. In this way, the distance through which a large current flows can be shortened, so that the amount of heat generated during current flow can be suppressed.

[0055] Further, the downstream terminal connection portion 44, the third heat capacity portion 73b and the second heat capacity portion 72b connected to the downstream terminal connection portion 44, and the symmetrical terminal connection portion 48, the third heat capacity portion 73b and the second heat capacity portion 72b connected to the symmetrical terminal connection portion 48 are positioned in point symmetry. Here, the negative busbar 24 and the positive busbar 26 are used by being reversed in the plate thickness direction. For this reason, the busbar 20b can be turned into the negative busbar 24 simply by reversing the front and back orientation. In the negative busbar 24, the downstream terminal connection portion 44 functions as the upstream terminal connection portion 45 located most upstream in the current path of the busbar 20b. Therefore, while the negative busbar 24 and the positive busbar 26 have the same configuration, the distance through which a large current flows on the upstream side of the current path of the busbar 20b in the negative busbar 24 can be shortened, and the distance through which a large current flows on the downstream side of the current path of the busbar 20b in the positive busbar 26 can be shortened.

[0056] D. Fourth embodiment: FIG. 10 is a perspective view showing a detailed configuration of the busbar 20c of the fourth embodiment. FIG. 11 is a top view showing a detailed configuration of the busbar 20c of the fourth embodiment. The busbar 20c of the fourth embodiment is different from the busbar 20b of the third embodiment in that it further has a fourth heat capacity increasing portion 74c. Since the other configurations are the same as the busbar 20b of the third embodiment, the same configurations are given the same reference numerals and detailed description thereof will be omitted. For convenience of explanation, the busbar 20c of this embodiment is a positive electrode busbar 26. However, it is of course possible to use the negative electrode busbar 24. In the case of using the negative electrode busbar 24, the direction of current flow is reversed, so that the downstream terminal connection portion 44 functions as the upstream terminal connection portion 45.

[0057] The fourth heat capacity increasing portion 74c is formed as a part of the downstream terminal connection portion 44 or as a part of the symmetric terminal connection portion 48 in the downstream terminal connection portion 44 located at the most downstream side in the current path of the busbar 20c among the multiple terminal connection portions 40 and the symmetric terminal connection portion 48 located at a point symmetrical position with respect to the downstream terminal connection portion 44. As a result, the length of the downstream terminal connection portion 44 along the first direction D1 is longer than the length in the short direction of the main body portion 50 to which the downstream terminal connection portions 44 are connected. Furthermore, the length of the symmetric terminal connection portion 48 along the first direction D1 is longer than the length in the short direction of the main body portion 50 to which the symmetric terminal connection portions 48 are connected. In this embodiment, the "point symmetrical position" means a point symmetrical position with respect to the center of gravity of the busbar 20c as the center point on a plane along the first direction D1 and the second direction D2. In addition, in Figs. 10 and 11, for convenience of explanation, the formation position of the fourth heat capacity increasing portion 74c is indicated by hatching.

[0058] In the positive busbar 26, the current flowing through the busbar 20c during energization flows from each terminal connection portion 40 through the pair of main body portions 50 and the conductive portion 60 to the downstream terminal connection portion 44. In the present embodiment, the current flows to the downstream terminal connection portion 44 through the conductive portion 60 as well as the first heat capacity increasing portion 71, the second heat capacity increasing portion 72b, and the third heat capacity increasing portion 73b. For this reason, the temperature of the busbar 20c as the positive busbar 26 tends to increase toward the downstream side during energization, and the temperature tends to increase most easily at the downstream terminal connection portion 44. However, in the busbar 20c of the present embodiment, the fourth heat capacity increasing portion 74c that increases the heat capacity is formed as a part of the downstream terminal connection portion 44, and therefore the temperature increase of the busbar 20c can be effectively suppressed.

[0059] The fourth heat capacity increasing portion 74c is formed on the downstream terminal connection portion 44 and the symmetric terminal connection portion 48 on the side closer to the adjacent terminal connection portion 40 in the first direction D1. Due to the formation of the fourth heat capacity increasing portion 74c, the dimensions of the downstream terminal connection portion 44 and the symmetric terminal connection portion 48 in the first direction D1 are both larger than the dimensions of the other terminal connection portions 40 excluding the downstream terminal connection portion 44 and the symmetric terminal connection portion 48 in the first direction D1. In addition, the dimensions of the downstream terminal connection portion 44 and the symmetric terminal connection portion 48 in the first direction D1 are both larger than the dimensions of the main body portion 50 in the second direction D2 (short direction).

[0060] In place of the conductive member 90 for connecting the battery packs 100 in series, a conductive member 90c that covers the entire downstream terminal connection portion 44 including the fourth heat capacity increasing portion 74c in the first direction D1 may be connected to the battery pack 100 including the busbar 20c of this embodiment, as shown by the dashed line in FIG. 11. The conductive member 90c has a larger dimension along the first direction D1 than the conductive member 90 connected to the battery pack 100 of the first embodiment. By connecting the conductive member 90c that covers the entire downstream terminal connection portion 44 including the fourth heat capacity increasing portion 74c in the first direction D1, the contact area between the downstream terminal connection portion 44 and the conductive member 90c can be further increased. Therefore, the current of the busbar 20c can be further dispersed, and the temperature rise of the busbar 20c can be further suppressed.

[0061] The busbar 20c of the fourth embodiment described above provides the same effects as those of the third embodiment. In addition, the fourth heat capacity increasing portion 74c, which increases the heat capacity, is formed in the downstream terminal connection portion 44, which is located furthest downstream in the current path of the busbar 20c among the multiple terminal connection portions 40, and therefore, a temperature rise in the busbar 20c can be effectively suppressed.

[0062] The fourth heat capacity increasing portion 74c is formed in the downstream terminal connection portion 44 and in the symmetric terminal connection portion 48 that is point-symmetric with respect to the downstream terminal connection portion 44. The negative busbar 24 and the positive busbar 26 are used by being inverted in the plate thickness direction. Therefore, the busbar 20c can be made into the negative busbar 24 simply by inverting the front and back directions. In the negative busbar 24, the downstream terminal connection portion 44 functions as the upstream terminal connection portion 45 that is located most upstream in the current path of the busbar 20c. Therefore, while the negative busbar 24 and the positive busbar 26 have the same configuration, the fourth heat capacity increasing portion 74c can be located most upstream in the current path of the busbar 20c in the negative busbar 24, and the fourth heat capacity increasing portion 74c can be located most downstream in the current path of the busbar 20c in the positive busbar 26. In other words, the busbar 20c in which the fourth increased heat capacity portions 74c are formed on the most upstream and most downstream sides in the current path of the busbar 20c can be used as both the negative electrode busbar 24 and the positive electrode busbar 26.

[0063] Furthermore, according to an embodiment in which a conductive member 90c is connected to cover the entire downstream terminal connection portion 44 including the fourth heat capacity increasing portion 74c in the first direction D1, the current in the bus bar 20c can be further dispersed, thereby further suppressing the temperature rise of the bus bar 20c.

[0064] E. Fifth embodiment: FIG. 12 is a perspective view showing a detailed configuration of a busbar 20d of the fifth embodiment. FIG. 13 is a top view showing a detailed configuration of a busbar 20d of the fifth embodiment. The busbar 20d of the fifth embodiment differs from the busbar 20b of the third embodiment in that it has two heat capacity increasing portions 70d instead of the two heat capacity increasing portions 70b. Since the other configurations are the same as those of the busbar 20b of the third embodiment, the same configurations are denoted by the same reference numerals and detailed descriptions thereof will be omitted. In addition, a case where the busbar 20d is a positive electrode busbar 26 will be representatively described.

[0065] The two heat capacity increasing portions 70d each include a second heat capacity increasing portion 72d and a third heat capacity increasing portion 73d.

[0066] The second heat capacity increasing portions 72d are formed to extend in the first direction D1 at the ends in the first direction D1 of the pair of main bodies 50. The dimension of the second heat capacity increasing portion 72d in the fifth embodiment along the first direction D1 is smaller than the dimension of the second heat capacity increasing portion 72b in the third embodiment along the first direction D1.

[0067] The third heat capacity increasing portion 73d is formed in parallel with the conductive portion 60 near the end portion of the pair of main body portions 50 in the first direction D1 opposite to the side where the second heat capacity increasing portion 72d is formed. One of the third heat capacity increasing portions 73d connects the first main body portion 51 to the end portion of the second heat capacity increasing portion 72d connected to the second main body portion 52, and the other of the third heat capacity increasing portion 73d connects the second main body portion 52 to the end portion of the second heat capacity increasing portion 72d connected to the first main body portion 51. In this embodiment, the second heat capacity increasing portion 72d and the third heat capacity increasing portion 73d are connected to each other via an R-shape.

[0068] In this embodiment, the downstream terminal connection portion 44 located most downstream in the current path of the bus bar 20d serving as the positive bus bar 26 and the third thermal capacity increasing portion 73d partially overlap each other when viewed from the second direction D2.

[0069] The busbar 20d of the fifth embodiment described above provides the same effects as those of the third embodiment. In addition, since the dimension of the second thermal capacity increasing portion 72d along the first direction D1 is formed relatively small, the current path of the busbar 20d can be prevented from becoming excessively long, and as a result, the temperature rise of the busbar 20d can be further suppressed.

[0070] F. Experiments: F-1. Experiment 1 A simulation experiment of the maximum temperature and temperature distribution was performed for the busbars 20, 20b to 20d of the first and third to fifth embodiments. The simulation was performed under boundary conditions where the total current output from each battery 10 was 200 [A] in a windless atmospheric environment at 20°C for the battery pack 100 in which the busbars 20, 20b to 20d were assembled. Note that the maximum temperature means the maximum value of the temperature change in each of the busbars 20, 20b to 20d, based on a state in which no current flows. Moreover, the busbars 20, 20b to 20d used in the simulation are all positive electrode busbars 26.

[0071] <Sample> Sample 1: Bus bar 20 of the first embodiment Sample 2: Bus bar 20b of the third embodiment Samples 3 and 5: Busbar 20c according to the fourth embodiment Sample 4: Bus bar 20d of the fifth embodiment

[0072] Sample 5 is a sample in which a conductive member 90c is assembled instead of the conductive member 90. In each of Samples 1 to 4, the same conductive member 90 as in the first embodiment is assembled.

[0073] <Maximum temperature simulation results> Fig. 14 is an explanatory diagram showing a simulation of the maximum temperature. In Fig. 14, the vertical axis indicates the temperature change (ΔT (°C)) based on the state where no current is flowing. In Fig. 14, the temperature suppressed due to improved heat dissipation and the temperature suppressed due to suppressed heat generation are shown for Samples 2 to 5, respectively, based on Sample 1. The heat dissipation property of a sample is correlated with the surface area of ​​the sample.

[0074] For example, when comparing sample 1 and sample 2, the temperature change of sample 1 was estimated to be 20.2°C, while the temperature change of sample 2 was estimated to be 11.3°C. Compared to sample 1, the temperature change of sample 2 was suppressed by 4.0°C due to improved heat dissipation caused by an increased surface area, and the temperature change was suppressed by 4.9°C due to the suppression of the amount of heat generated. Thus, the temperature rise of sample 2 is more suppressed than that of sample 1. Similarly, the temperature rise of samples 3 to 5 is more suppressed than that of sample 1. The reason for this is that samples 2 to 5 further have other heat capacity increasing parts 70b to 70d in addition to the heat capacity increasing part 70 (first heat capacity increasing part 70) that sample 1 has. Also, the temperature rise of samples 3 and 5 having the fourth heat capacity increasing part 74c is further suppressed compared to samples 2 and 4 not having the fourth heat capacity increasing part 74c. The reason for this is that the fourth heat capacity increasing part 74c is formed in the downstream terminal connecting part 44, which is most likely to increase in temperature when electricity is applied. Moreover, a comparison between Sample 3 and Sample 5 shows that the temperature rise can be further suppressed by increasing the contact area between the downstream terminal connecting portion 44 and the conductive member 90c.

[0075] <Temperature distribution simulation results> 15 to 18 are explanatory diagrams showing simulations of temperature distributions in samples 1 to 4, respectively. In Figs. 15 to 18, differences in temperature are indicated by hatching. From the results shown in Figs. 15 to 18, it can be seen that in all samples, the temperature tends to increase toward the downstream side of the current path. Furthermore, in all samples 2 to 4, the temperature increase is suppressed compared to sample 1.

[0076] F-2. Experiment 2 A simulation experiment of the current density distribution was carried out for the same samples 2, 3, and 5 as in Experiment 1. The simulation was carried out under boundary conditions where the total current output from each battery 10 was 200 [A] for the battery pack 100 having the bus bars 20b and 20c assembled thereto in a windless atmospheric environment at 20°C.

[0077] <Simulation results of current density distribution> FIG. 19 is an explanatory diagram showing a simulation of the current density distribution of the sample 2. In FIG. 19, the difference in current density is indicated by hatching. In FIG. 19, the current density when the sample 2 is viewed from two directions, the front and back, is shown. In FIG. 19, the bus bar 20b viewed from the front side indicates the bus bar 20b viewed from the top side of the assembled battery 100 shown in FIG. 1, and the bus bar 20b viewed from the back side indicates the bus bar 20b viewed from the battery 10 side of the assembled battery 100 shown in FIG. 1. From the results shown in FIG. 19, it can be seen that the current density of the main body 50 tends to increase toward the downstream side of the current path. It can also be seen that the current density tends to increase especially around the bent portion 46 connecting the main body 50 and the downstream terminal connection portion 44.

[0078] FIG. 20 is an explanatory diagram showing a simulation of the current density distribution around the downstream terminal connection part 44. In FIG. 20, the difference in current density is shown by hatching. In FIG. 20, the periphery of the downstream terminal connection part 44 is shown enlarged in the simulation for the samples 2, 3, and 5. In the samples 3 and 5, the fourth heat capacity increase part 74c is formed in the downstream terminal connection part 44, compared to the sample 2. Therefore, in the samples 3 and 5, the current flowing through the main body part 50 to the downstream terminal connection part 44 or the fourth heat capacity increase part 74c and the current flowing through the third heat capacity increase part 73b to the downstream terminal connection part 44 or the fourth heat capacity increase part 74c are suppressed from being added together. In the samples 3 and 5, even if the currents are added together, the distance over which the currents flow is short, so that an increase in the current density is suppressed. In the sample 5, the current density of the fourth heat capacity increase part 74c is reduced, compared to the sample 3. The reason for this is that the contact area between the fourth heat capacity increasing portion 74c and the conductive member 90c is larger, so that the current in the bus bar 20c can be dispersed more.

[0079] G. Other embodiments: G-1. Other embodiment 1: In the above embodiment, the conductive members 90, 90c and the bus bars 20, 20a to 20d are made of copper, but may be made of any conductive material such as aluminum or silver. The heat capacity increasing portions 70, 70a to 70d may be made of the same material as the other portions of the bus bars 20, 20a to 20d except for the heat capacity increasing portions 70, 70a to 70d, or may be made of a different conductive material or may be made of a non-conductive material. For example, the other portions of the bus bars 20, 20a to 20d except for the heat capacity increasing portions 70, 70a to 70d may be made of copper, and the heat capacity increasing portions 70, 70a to 70d may be made of aluminum, ceramic, resin, or the like. This configuration can also increase the heat capacity of the bus bars 20, 20a to 20d, and therefore can suppress a temperature rise of the bus bars 20, 20a to 20d when current is applied.

[0080] G-2. Other embodiment 2: The configurations of the busbars 20, 20a to 20d in the above-described embodiments are merely examples and can be modified in various ways. For example, in the busbar 20a of the second embodiment, the heat capacity increasing portion 70a may also function as a conductive portion, so that the conductive portion 60 is omitted. That is, even if there is only one bridge portion connecting the pair of main bodies 50, the bridge portion corresponds to the heat quantity increasing portion 70a as long as the bridge portion has a cross-sectional area larger than that of the first main body portion 51 and the second main body portion 52 constituting the pair of main bodies 50. In this embodiment, the heat capacity increasing portion 70a corresponds to the heat capacity increasing portion and the conductive portion in the present disclosure. Also, for example, in the busbar 20c of the fourth embodiment, the fourth heat capacity increasing portion 74c formed in the symmetric terminal connection portion 48 may be omitted. For example, in the busbars 20b, 20d of the third and fifth embodiments, one of the two heat capacity increasing portions 70b, 70d may be omitted, and the third heat capacity increasing portion 73b, 73d may be omitted. That is, in general, the second heat capacity increasing portion 72d may be formed at an end portion in the first direction D1 of at least one of the pair of main body portions 50, extending in the first direction D1. For example, the busbar 20d of the fifth embodiment may further include a fourth heat capacity increasing portion 74c similar to that of the fourth embodiment. With such a configuration, the same effects as those of the above-mentioned embodiments can be achieved.

[0081] G-3. Other embodiment 3: In the above embodiment, busbars 20, 20a, 20d preferably have a point-symmetric shape, similar to busbars 20b, 20c. Since busbars 20, 20a to 20d have a point-symmetric shape, they can be used as positive electrode busbar 26 or negative electrode busbar 24 simply by inverting them. In addition, busbars 20, 20a to 20d do not have to have a point-symmetric shape, and an even number of terminal connection portions 40 may be formed, and paired terminal connection portions 40 may be arranged in point-symmetric positions.

[0082] The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features in each embodiment corresponding to the technical features in each form described in the Summary of the Invention column can be appropriately replaced or combined in order to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if the technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0083] 10... battery, 12... battery body, 13... upper surface, 14... negative electrode terminal, 16... positive electrode terminal, 18... measurement terminal, 20, 20a to 20d... bus bars, 24... negative electrode bus bar, 26... positive electrode bus bar, 40... terminal connection portion, 42... through hole, 44... downstream terminal connection portion, 45... upstream terminal connection portion, 46... bent portion, 48... symmetrical terminal connection portion, 50... body portion, 51... first portion Body portion, 52... second body portion, 60... conductive portion, 70, 70a, 70b, 70d... heat capacity increasing portion, 71... first heat capacity increasing portion, 72b, 72d... second heat capacity increasing portion, 73b, 73d... third heat capacity increasing portion, 74c... fourth heat capacity increasing portion, 90, 90c... conductive member, 92... through hole, 100... battery pack, D1... first direction, D2... second direction, L1 to L5... dimensions

Claims

1. A bus bar is provided for connecting terminals of the same polarity of a plurality of rectangular batteries having positive and negative terminals on the same plane in a first direction, the positive and negative terminals being arranged in a staggered manner in a battery pack, the bus bar comprising: A plurality of terminal connection parts respectively connected to the plurality of terminals of the same polarity; a pair of main body portions each connected to the terminal connection portions and extending in the first direction and parallel to each other; a conductive portion that electrically connects the pair of main body portions to each other; Equipped with The bus bar further includes a heat capacity increasing portion that increases a heat capacity, the heat capacity increasing portion has the same plate thickness as the main body portion or the terminal connection portion, and the bus bar is formed by extending from the main body portion or the terminal connection portion; In a battery pack including the plurality of batteries, the bus bar connects the positive terminals of the plurality of batteries to each other; The heat capacity increasing portion has a fourth heat capacity increasing portion, the fourth heat capacity increasing portion is formed as a part of a downstream terminal connection portion that is located most downstream in a current path of the bus bar among the plurality of terminal connection portions, a dimension of the downstream terminal connection portion along the first direction is larger than a dimension of the downstream terminal connection portion along a short side direction of the main body portion to which the downstream terminal connection portion is connected, Battery pack.

2. 2. The battery pack according to claim 1, a cross-sectional area of ​​the increased heat capacity portion in a cross section perpendicular to a current path of the bus bar is larger than a cross-sectional area of ​​a portion of the bus bar excluding the increased heat capacity portion in the cross section. Battery pack.

3. The battery pack according to claim 1 or 2, The heat capacity increasing portion includes a first heat capacity increasing portion, The first heat capacity increasing portion is formed in parallel with the conductive portion and connects the pair of main body portions to each other. Battery pack.

4. The battery pack according to any one of claims 1 to 3, The heat capacity increasing portion has a second heat capacity increasing portion, The second heat capacity increasing portion is formed at an end portion in the first direction of at least one of the pair of body portions, and extends in the first direction from a position where the terminal connection portion closest to the end portion is connected to the body portion. Battery pack.

5. The battery pack according to claim 4, The heat capacity increasing section further includes a third heat capacity increasing section, the third heat capacity increasing portion is formed in parallel with the conductive portion and connects the other of the pair of body portions and the second heat capacity increasing portion to each other. Battery pack.

6. The battery pack according to any one of claims 1 to 5, The heat capacity increasing portion is formed of the same material as other portions except the heat capacity increasing portion. Battery pack.

7. A battery pack in which a plurality of rectangular batteries having positive and negative terminals on the same plane are arranged along a first direction, the positive and negative terminals being arranged in a staggered pattern, the battery pack comprising: a bus bar for connecting terminals of the same polarity of the plurality of batteries to each other, A plurality of terminal connection parts respectively connected to the plurality of terminals of the same polarity; a pair of main body portions each connected to the terminal connection portions and extending in the first direction and parallel to each other; a conductive portion that electrically connects the pair of main body portions to each other; Equipped with The bus bar further includes a heat capacity increasing portion that increases a heat capacity, the heat capacity increasing portion has the same plate thickness as the main body portion or the terminal connection portion, and the bus bar is formed by extending from the main body portion or the terminal connection portion; In a battery pack including the plurality of batteries, the bus bar connects the negative terminals of the plurality of batteries to each other; The heat capacity increasing portion has a fourth heat capacity increasing portion, the fourth heat capacity increasing portion is formed as a part of an upstream terminal connection portion that is located most upstream in a current path of the bus bar among the plurality of terminal connection portions, A dimension of the upstream terminal connection portion along the first direction is larger than a dimension of the upstream terminal connection portion along a short side direction of the main body portion to which the upstream terminal connection portion is connected. Battery pack.

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