Bus bar

Abstract

To provide a busbar that can suppress increases in rigidity and temperature. [Solution] A plate-shaped busbar 40 made of a conductive material is connected to terminals provided on both sides of two battery cells 11 arranged in a predetermined direction, and comprises a first connection portion 58 connected to one terminal of the two battery cells, a second connection portion 60 connected to the other terminal of the two battery cells, and a first through hole 64 and a second through hole 62 provided in the region between the first and second connection portions and arranged vertically relative to each other, with a recess 70 formed on the edge of the first through hole on the side of the second through hole that is recessed toward the opposite side of the second through hole.

Description

Technical Field

[0001] The present invention relates to a bus bar.

Background Art

[0002] The following Patent Document 1 discloses a technique of forming slits (through holes) in a bus bar that connects terminals provided on the outer surfaces of battery cells arranged in a predetermined direction.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] If the rigidity of the bus bar is too high, the bus bar is likely to separate from the terminals of the battery cells when the battery cells are moved by an external force. Also, when the number of through holes provided in the bus bar increases, the heat dissipation of the bus bar decreases.

[0005] The invention of the above Patent Document 1 has room for improvement in suppressing an increase in the rigidity of the bus bar and suppressing an increase in the temperature of the bus bar.

[0006] In consideration of the above facts, an object of the present invention is to obtain a bus bar capable of suppressing an increase in rigidity and temperature.

Means for Solving the Problems

[0007] The busbar of the first embodiment is a plate-shaped busbar made of a conductive material that is connected to terminals provided on both sides of two battery cells arranged in a predetermined direction in a direction perpendicular to the predetermined direction and the vertical direction, and comprises a first connection portion connected to the terminal of one of the two battery cells, a second connection portion connected to the terminal of the other of the two battery cells, and a first through hole and a second through hole provided in the region between the first connection portion and the second connection portion and arranged vertically relative to each other, wherein a recess is formed on the edge of the first through hole on the side of the second through hole, recessing toward the opposite side of the second through hole.

[0008] The busbar of the first embodiment is a plate-shaped busbar that connects to terminals provided on both orthogonal sides of two battery cells arranged in a predetermined direction. The first connection portion of the busbar is connected to one terminal of two adjacent battery cells, and the second connection portion is connected to the other terminal of two adjacent battery cells. The busbar has a first through hole and a second through hole formed in the region between the first and second connection portions, which are arranged vertically relative to each other.

[0009] Since the busbar in the first embodiment has a first through hole and a second through hole formed therein, the increase in rigidity is suppressed.

[0010] Furthermore, in the busbar of the first embodiment, a recess is formed on the edge of the first through-hole on the side facing the second through-hole, indenting toward the opposite side of the second through-hole. As a result of the recess, the width (vertical dimension) and heat dissipation area of ​​the region (transmission path) between the first and second connection parts are larger. As a result of the recess, the electrical resistance of the transmission path is reduced and heat dissipation is improved. Therefore, the busbar is less likely to overheat.

[0011] In the second embodiment, the busbar has a first through-hole whose vertical width is greater than the second through-hole's vertical width.

[0012] The busbar of the second embodiment allows for a larger width in the region (transmission path) between the first and second connection parts and a larger heat dissipation area compared to the case where a recess is formed on the edge of the second through-hole on the first through-hole side.

[0013] The busbar of the third embodiment comprises, in the first or second embodiment, a first plate-like portion including the first connecting portion, a second plate-like portion including the second connecting portion and located on the same plane as the first plate-like portion, a pair of rising wall portions extending in the orthogonal direction away from the battery cell from the opposing edges of the first plate-like portion and the second plate-like portion, and a central plate portion connecting the opposing edges of the pair of rising wall portions, wherein the first through hole is formed to span the first plate-like portion, the second plate-like portion, the pair of rising wall portions, and the central plate portion, and the recess is formed only in the central plate portion.

[0014] In the busbar of the third embodiment, the rigidity of the connection between the first plate-like portion and the second plate-like portion and the rising wall portion tends to be high. However, this connection portion has a portion that is wider vertically than the portion where the recess of the first through-hole is formed. Therefore, the rigidity of this connection portion can be reduced compared to the case where a recess is formed in this connection portion. Furthermore, in the busbar of the third embodiment, the recess is formed only in the central plate portion. The portion where the recess is formed is less likely to have its rigidity reduced by the first through-hole, but the central plate portion has lower rigidity compared to the above-mentioned connection portion. Therefore, although a recess is formed in the central plate portion, it is difficult to increase its rigidity.

[0015] In the fourth embodiment, the busbar is such that, in the first or second embodiment, at least a portion of the portion of the first through-hole where the recess is formed is located above or below the region between the straight line connecting the upper ends of the first and second connecting portions and the straight line connecting the lower ends of the first and second connecting portions.

[0016] Electricity flows easily in the region between the straight line connecting the upper ends of the first and second connection parts and the straight line connecting the lower ends of the first and second connection parts. In the busbar of the fourth embodiment, at least a portion of the area where the recess of the first through-hole is formed is located above or below this region. Therefore, there is little risk of the electrical resistance of the busbar increasing due to the first through-hole. [Effects of the Invention]

[0017] As described above, the bus bar according to the present invention has an excellent effect of being able to suppress an increase in rigidity and temperature.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 9 is a perspective view seen from the left side showing a part of a battery module including a bus bar according to an embodiment. [Figure 2] FIG. 12 is a perspective view seen from the right side showing a part of the battery module. [Figure 3] FIG. 15 is an exploded perspective view of a bus bar and two battery cells. [Figure 4] FIG. 18 is a side view of a bus bar and two battery cells.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, a battery module 10 including a bus bar according to an embodiment will be described with reference to the accompanying drawings. In each figure, the arrow UP, the arrow FR, and the arrow LH indicate the upper side in the vehicle up-down direction, the front side in the vehicle front-rear direction (predetermined direction), and the left side in the vehicle left-right direction (orthogonal direction), respectively.

[0020] The battery module 10 of the present embodiment is mounted on a vehicle via a case (not shown). The vehicle of the present embodiment is a battery electric vehicle (BEV: Battery Electric Vehicle).

[0021] At least one battery module 10 is housed in the case of the present embodiment. The power of the battery module 10 is supplied to, for example, an electric motor (not shown) that applies a driving force to the drive wheels of the vehicle.

[0022] As shown in FIG. 1, the battery module 10 includes a plurality of battery cells 11 that are lithium ion secondary batteries, a plurality of separators 20 that are insulating members located between adjacent battery cells 11, a plurality of bus bars 40, and a restraint member.

[0023] Each battery cell 11 has a metal, rectangular cell case 12. The front shape of the cell case 12 is a rectangle, with the left-right dimension being larger than the top-down dimension. As shown in Figures 1 and 2, a positive terminal (terminal) 13P is provided on one of the left and right end faces of the cell case 12, and a negative terminal (terminal) 13N is provided on the other end face. The positive terminal 13P and the negative terminal 13N are made of metal. In this embodiment, as shown in Figures 1 and 2, the left-right orientation of each battery cell 11 is determined so that the positive terminal 13P and the negative terminal 13N of each battery cell 11 are arranged alternately in the front-back direction.

[0024] Each resin separator 20 is a roughly rectangular parallelepiped-shaped component. Each separator 20 is positioned between the two battery cells 11.

[0025] Each battery cell 11 and each separator 20 is restrained by a restraining member (not shown). Therefore, adjacent battery cells 11 and separators 20 are in contact with each other.

[0026] Next, we will describe the multiple metal busbars 40. The busbars 40 are made of a metal material such as copper, which has excellent conductivity.

[0027] As shown in Figures 3 and 4, the busbar 40 is an integrally molded product having a first plate-like portion 42, a second plate-like portion 46, a first rising wall portion (rising wall portion) 50, a second rising wall portion (rising wall portion) 52, and a central plate portion 54. The busbar 40 of this embodiment is manufactured, for example, by press molding a metal plate.

[0028] The first plate-like portion 42 and the second plate-like portion 46 are flat plate-shaped parts. The first plate-like portion 42 has a main body portion 43 with a substantially rectangular side shape and a downward extension portion 44 extending downward from the main body portion 43. The upper edges of the first plate-like portion 42 and the upper edges of the second plate-like portion 46 are substantially the same in the vertical direction. When the busbar 40 is in a free state, the first plate-like portion 42 and the second plate-like portion 46 are located substantially on the same plane.

[0029] The first rising wall section 50 and the second rising wall section 52 are connected to the opposing edges of the main body section 43 and the second plate-like section 46, respectively. The front shape of the first rising wall section 50 and the second rising wall section 52 is a roughly rectangular shape, with the vertical dimension being longer than the horizontal dimension. One edge of the first rising wall section 50 in the left-right direction is connected to the edge of the main body section 43, and one edge of the second rising wall section 52 in the left-right direction is connected to the edge of the second plate-like section 46. When the busbar 40 is in a free state, the first rising wall section 50 and the second rising wall section 52 are roughly perpendicular to the first plate-like section 42 and the second plate-like section 46.

[0030] The front and rear edges of the central plate section 54 are connected to the opposing edges of the main body section 43 and the second plate-like section 46 of the first rising wall section 50 and the second rising wall section 52, respectively. The side shape of the central plate section 54 is approximately rectangular, with the left-right dimension being longer than the vertical dimension. When the busbar 40 is in a free state, the central plate section 54 is approximately perpendicular to the first rising wall section 50 and the second rising wall section 52, and approximately parallel to the first plate-like section 42 and the second plate-like section 46.

[0031] The main body portion 43 of the first plate-like portion 42 is provided with a first welded portion (first connecting portion) 58, and the second plate-like portion 46 is provided with a second welded portion (second connecting portion) 60. The first welded portion 58 and the second welded portion 60 are substantially the same shape. That is, the side shape of the first welded portion 58 and the second welded portion 60 is approximately circular, and a through hole is formed in the center. The first welded portion 58 and the second welded portion 60 are counterbored, and their plate thickness is thinner than other areas of the main body portion 43 and the second plate-like portion 46. As shown in Figure 4, the first welded portion 58 and the second welded portion 60 are located above the vertical center position 40C of the main body portion 43 and the second plate-like portion 46. As shown in Figure 4, the region between the straight line LU connecting the upper edge of the first weld 58 and the upper end of the second weld 60 in the busbar 40, and the straight line LD connecting the lower edge of the first weld 58 and the lower end of the second weld 60, is referred to as the main power transmission region 45.

[0032] In the main body portion 43, the first rising wall portion 50, the central plate portion 54, the second rising wall portion 52, and the portion of the second plate-like portion 46 located below the central position 40C, a slit 61 is formed that extends linearly along the front-to-back direction in a side view. Here, the width (vertical dimension) of the slit 61 is defined as the first width W1.

[0033] In the main body portion 43, the first rising wall portion 50, the central plate portion 54, the second rising wall portion 52, and the second plate-like portion 46, located above the main power transmission area 45, a slit (second through hole) 62 is formed that extends linearly along the front-rear direction in a side view. The side shape of the slit 62 is substantially the same as that of the slit 61. That is, the width of the slit 62 is the first width W1.

[0034] A slit (first through hole) 64 is formed in the vertical center of the main body 43, the first rising wall 50, the central plate 54, the second rising wall 52, and the second plate-like portion 46. The front-to-back dimensions of the slit 64 are approximately the same as those of slits 61 and 62. The slit 64 has a narrow portion 65 which is formed in the central plate 54, a first wide portion 67 which is located on the first plate-like portion 42 side of the narrow portion 65 and connected to the narrow portion 65, and a second wide portion 68 which is located on the second plate-like portion 46 side of the narrow portion 65 and connected to the narrow portion 65. The second width W2, which is the width (vertical dimension) of the first wide portion 67 and the second wide portion 68, is greater than the width of the narrow portion 65 and the first width W1. In other words, a recess 70 is formed on the edge of the portion of the slit 64 on the slit 62 side where the narrow portion 65 is formed.

[0035] As shown in Figures 1 and 2, each busbar 40 is welded to the positive terminal 13P and negative terminal 13N located on the left and right sides of two adjacent battery cells 11. The first weld portion 58 of each busbar 40 located on the left side of the battery cell 11 is welded to the negative terminal 13N of the battery cell 11 using a laser beam emitted from a welding device (not shown) located to the left of the busbar 40. Furthermore, the second weld portions 60 of these busbars 40 are welded to the positive terminal 13P of the battery cell 11 using a laser beam emitted from a welding device. In addition, the first weld portion 58 of each busbar 40 located on the right side of the battery cell 11 is welded to the positive terminal 13P of the battery cell 11 using a laser beam emitted from a welding device located to the right of the busbar 40, and the second weld portions 60 of these busbars 40 are welded to the negative terminal 13N of the battery cell 11 using a laser beam emitted from a welding device. In other words, in the battery module 10 of this embodiment, each battery cell 11 is connected in series by a plurality of busbars 40.

[0036] In this way, the battery module 10 is completed by welding the busbars 40 to the positive terminal 13P and negative terminal 13N of each battery cell 11. The assembled battery module 10 is then housed in a case, and this case is fixed to the vehicle body.

[0037] (Mechanism of action and effect) Next, the operation and effects of the embodiment will be described.

[0038] When electricity flows between the positive terminal 13P and the negative terminal 13N connected to the busbar 40, this electricity flows through the region between the first weld 58 and the second weld 60 in the busbar 40. Hereinafter, the region in the busbar 40 through which electricity flows will be referred to as the transmission path 41. This transmission path 41 is a wider region than the main transmission region 45. That is, electricity may flow through the region above the main transmission region 45 in the busbar 40, or through the region below the main transmission region 45 in the busbar 40. Furthermore, the main transmission region 45 is particularly conducive to electricity flow within the transmission path 41.

[0039] Each busbar 40 in this embodiment is a plate-shaped member connected to the positive terminal 13P and negative terminal 13N provided on both sides in the left-right direction (orthogonal direction) of a plurality of battery cells 11 arranged in the front-rear direction. The first welded portion 58 of the busbar 40 is connected to one terminal (one of the positive terminal 13P and negative terminal 13N) of two adjacent battery cells 11, and the second welded portion 60 is connected to the other terminal (the other of the positive terminal 13P and negative terminal 13N) of two adjacent battery cells 11. The busbar 40 has slits 62 and 64 formed in it, which are provided in the power transmission line 41 and are arranged vertically relative to each other.

[0040] As described above, the bus bar 40 has slits 61, 62, and 64 formed therein. Therefore, the mechanical strength (rigidity) of the bus bar 40 is reduced by the amount to which the slits 61, 62, and 64 are formed. Furthermore, the slit 64 has a first wide portion 67 and a second wide portion 68 having a second width W2 that is larger than the first width W1 of the slits 61 and 62. Therefore, these slits 61, 62, and 64 prevent the bus bar 40 from becoming too rigid. Consequently, for example, when an external force is applied to the bus bar 40 from the battery cell 11 due to vibrations during vehicle operation, or when each battery cell 11 expands and contracts, the bus bar 40 can deform flexibly and absorb this external force. Therefore, in such cases, there is little risk of the first welded portion 58 and the second welded portion 60 of each bus bar 40 separating from the corresponding positive terminal 13P or negative terminal 13N.

[0041] Furthermore, in the bus bar 40, a recess 70 is formed on the edge of the slit 64 on the slit 62 side, which is recessed toward the opposite side of the slit 62. As a result of the formation of the recess 70, the width (vertical dimension) of the transmission line 41 (main transmission area 45) and the heat dissipation area of ​​the bus bar 40 are larger. As a result of the formation of the recess 70, the electrical resistance in the transmission line 41 of the bus bar 40 is reduced and the heat dissipation is improved. Therefore, the bus bar 40 is less likely to overheat. In addition, electricity flows easily between the first welded part 58 and the second welded part 60 of each bus bar 40.

[0042] Furthermore, if a recess is formed on the edge of slit 62 on the slit 64 side, the vertical width of this recess will be smaller than that of the recess 70. In other words, in this case, the electrical resistance reduced by this recess will be smaller than the electrical resistance reduced by the formation of the recess 70, and the heat dissipation area of ​​the busbar 40 will also be smaller. In other words, the busbar 40 of this embodiment can reduce the electrical resistance in the transmission line 41 of the busbar 40 and improve the heat dissipation performance of the busbar 40 more easily than when a recess is formed on the edge of slit 62 on the slit 64 side.

[0043] Furthermore, in the busbar 40, the mechanical strength (rigidity) of the connection between the first plate-like portion 42 and the first rising wall portion 50, the connection between the second plate-like portion 46 and the second rising wall portion 52, the connection between the first rising wall portion 50 and the central plate portion 54, and the connection between the second rising wall portion 52 and the central plate portion 54 tends to be higher than that of other parts. However, these connection portions have a first wide portion 67 and a second wide portion 68 formed therein, which are wider vertically than the narrow portion 65 of the slit 64. Therefore, the rigidity of these connection portions can be reduced compared to the case where recesses are formed in these connection portions.

[0044] Furthermore, in the bus bar 40, the recess 70 is formed only in the central plate portion 54. The portion of the bus bar 40 in which the recess is formed is less likely to have its rigidity reduced by the slit 64, but the central plate portion 54 has lower rigidity compared to the connection portion. Therefore, although the recess 70 is formed in the central plate portion 54, the rigidity of the central plate portion 54 is not easily increased.

[0045] Furthermore, as mentioned above, the main transmission region 45 is a region within the transmission line 41 where electricity flows particularly easily. In the busbar 40, the narrow portion 65 where the recess 70 in the slit 64 is formed is located below the main transmission region 45. Therefore, compared to the case where the overall vertical width of the slit 64 is the second width W2, there is less risk that the slit 64 will increase the electrical resistance of the transmission line 41 of the busbar 40 or reduce the heat dissipation performance of the busbar 40.

[0046] Although busbars according to the embodiments have been described above, these can be modified as appropriate without departing from the spirit of the present invention.

[0047] For example, a slit 64 may be formed in the area where the slit 62 is formed in the embodiment, and a slit 62 may be formed in the area where the slit 64 is formed in the embodiment. In this case, a recess 70 is formed at the lower edge of the slit 64. Furthermore, in this case, the slit 62 is located below the main transmission area 45, and the narrow portion 65 is located above the main transmission area 45.

[0048] The slit 61 may be omitted from the busbar 40. Alternatively, in addition to the slits 61, 62, and 64, the busbar 40 may have slits that extend in the front-rear direction and span the main body portion 43, the first rising wall portion 50, the central plate portion 54, the second rising wall portion 52, and the second plate-like portion 46.

[0049] The vehicle may be an electric vehicle that is different from an electric vehicle and is equipped with an electric motor that utilizes the power of a battery module. For example, the vehicle may be a hybrid electric vehicle (HEV) or a plug-in hybrid electric vehicle (PHEV). [Explanation of Symbols]

[0050] 11 battery cells 13P Positive Terminal (Terminal) 13N Negative terminal (terminal) 40 Bus Bar 42 First plate-like portion 46 Second plate-like portion 50 First rising wall section (rising wall section) 52 Second rising wall section (rising wall section) 54 Center plate part 58. First weld (first connection) 60. Second weld (second connection) 62 Slit (Second Through Hole) 64 Slit (First through hole) 70 recess

Claims

1. A plate-shaped busbar made of a conductive material, connected to terminals provided on both sides of two battery cells arranged in a predetermined direction, in a direction perpendicular to the predetermined direction and the vertical direction, A first connection portion connected to the terminal of one of the two battery cells, A second connection portion connected to the other terminal of the two battery cells, A first through-hole and a second through-hole are provided in the region between the first connecting portion and the second connecting portion, and are arranged vertically relative to each other. Equipped with, A bus bar having a recess formed on the edge of the first through-hole on the side of the second through-hole, which is recessed toward the opposite side of the second through-hole.

2. The bus bar according to claim 1, wherein the vertical width of the first through-hole is greater than the vertical width of the second through-hole.

3. The first plate-shaped portion including the first connecting portion, A second plate-shaped portion that includes the second connecting portion and is located on the same plane as the first plate-shaped portion, A pair of rising wall portions extending in the orthogonal direction away from the battery cell from the opposing edges of the first plate-shaped portion and the second plate-shaped portion, A central plate portion connecting the opposing edges of a pair of the aforementioned rising wall portions, Equipped with, The first through-hole is formed to span the first plate-like portion, the second plate-like portion, the pair of rising wall portions, and the central plate portion. The bus bar according to claim 1 or claim 2, wherein the recess is formed only in the central plate portion.

4. The bus bar according to claim 1 or claim 2, wherein at least a portion of the part of the first through hole in which the recess is formed is located above or below the region between the straight line connecting the upper ends of the first and second connecting parts and the straight line connecting the lower ends of the first and second connecting parts.

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