Bus bar

Abstract

To provide a busbar that can suppress increases in rigidity and temperature. [Solution] The battery cell comprises a first plate-shaped portion 42 including a first connection portion 58 connected to one terminal of two battery cells 11, a second plate-shaped portion 46 including a second connection portion 60 connected to the other terminal of the two battery cells, a first rising wall portion connected to the opposite edge of the first plate-shaped portion with respect to the second plate-shaped portion, a second rising wall portion connected to the second plate-shaped portion, a central plate portion 54 connecting the first and second rising wall portions, and first through holes 61 and second through holes 62 provided in the region between the first and second connection portions and arranged vertically relative to each other, with a first auxiliary through hole 70 formed at the connection portion between the first rising wall portion and the first plate-shaped portion, and a second auxiliary through hole 75 formed at the connection portion between the second rising wall portion and the second plate-shaped portion.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 below 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, if the number of through holes provided in the bus bar increases, the heat dissipation performance of the bus bar will deteriorate.

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

[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] A busbar in 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 an orthogonal direction perpendicular to the predetermined direction and the vertical direction, comprising: a first plate-shaped portion including a first connecting portion connected to the terminal of one of the two battery cells; a second plate-shaped portion including a second connecting portion connected to the terminal of the other of the two battery cells; and a first rising wall portion extending in the orthogonal direction away from the battery cell from the edge of the first plate-shaped portion opposite to the second plate-shaped portion. The device comprises: a second rising wall portion extending in the orthogonal direction away from the battery cell from the edge of the second plate-shaped portion opposite to the first plate-shaped portion; a central plate portion connecting the opposing edges of the first rising wall portion and the second rising wall portion; and a first through hole and a second through hole provided in the region between the first and second connecting portions and aligned vertically with respect to each other, wherein a first auxiliary through hole is formed at the connection between the first rising wall portion and the first plate-shaped portion, and a second auxiliary through hole is formed at the connection between the second rising wall portion and the second plate-shaped portion.

[0008] In the busbar of the first embodiment, the connection between the first rising wall and the first plate-like portion, and the connection between the second rising wall and the second plate-like portion, are parts that greatly affect the rigidity of the busbar. Therefore, if the first auxiliary through-hole and the second auxiliary through-hole are formed in these parts, even if the first and second auxiliary through-holes are small, the rigidity of the busbar is easily reduced. For this reason, there is little risk that the electrical resistance of the busbar will increase significantly due to the first and second auxiliary through-holes. Consequently, it is possible to suppress an increase in the rigidity of the busbar.

[0009] Furthermore, since the first and second auxiliary through-holes can be made smaller, the heat dissipation area of ​​the busbar is less likely to decrease, and the electrical resistance of the busbar is less likely to increase. Therefore, the busbar is less likely to overheat.

[0010] In the second embodiment, the busbar is such that, in the first embodiment, the first auxiliary through-hole is formed at the connection between the first rising wall portion and the central plate portion, and the second auxiliary through-hole is formed at the connection between the second rising wall portion and the central plate portion.

[0011] In the busbar of the second embodiment, the first auxiliary through-hole is also formed at the connection between the first rising wall and the central plate, and the second auxiliary through-hole is also formed at the connection between the second rising wall and the central plate. This makes it easier to suppress an increase in the rigidity of the busbar.

[0012] In the third embodiment, the busbar is positioned such that, in the first or second embodiment, the first auxiliary through-hole and the second auxiliary through-hole are located above and below at least one of the regions 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.

[0013] 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 third embodiment, the first and second auxiliary through holes are located above or below this region. Therefore, there is little risk of the electrical resistance of the busbar increasing due to the first and second auxiliary through holes.

[0014] In the fourth embodiment, the busbar, in the first or second embodiment, is located above or below the central position of the busbar in the vertical direction, and the sum of the opening areas of the first through hole, the second through hole, the first auxiliary through hole, and the portion of the second auxiliary through hole located above or below the central position is greater than 50% of the sum of the opening areas of the first through hole, the second through hole, the first auxiliary through hole, and the second auxiliary through hole.

[0015] In the busbar of the fourth embodiment, the rigidity of the parts of the busbar where the first and second connection portions are provided tends to decrease. Therefore, the connection between the first and second connection portions and the terminals of the battery cell is easier to maintain. [Effects of the Invention]

[0016] As described above, the busbar according to the present invention has the excellent effect of suppressing increases in rigidity and temperature.

Brief Description of the Drawings

[0017] [Figure 1] It 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] It is a perspective view seen from the right side showing a part of the battery module. [Figure 3] It is an exploded perspective view of a bus bar and two battery cells. [Figure 4] It is a side view of a bus bar and two battery cells.

Modes for Carrying Out the Invention

[0018] Hereinafter, a battery module 10 including a bus bar according to an embodiment will be described with reference to the accompanying drawings. In the arrows UP, arrow FR, and arrow LH in each figure 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.

[0019] 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).

[0020] 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.

[0021] 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.

[0022] Each battery cell 11 has a metal rectangular parallelepiped cell case 12. The front shape of the cell case 12 is a rectangle with a larger left - right dimension than the up - down dimension. As shown in FIGS. 1 and 2, a positive electrode terminal (terminal) 13P is provided on one of the left and right end faces of the cell case 12, and a negative electrode terminal (terminal) 13N is provided on the other of the left and right end faces. The positive electrode terminal 13P and the negative electrode terminal 13N are made of metal. In this embodiment, as shown in FIGS. 1 and 2, the left - right direction of each battery cell 11 is determined so that the positive electrode terminals 13P and the negative electrode terminals 13N of each battery cell 11 are arranged alternately in the front - rear direction.

[0023] Each resin separator 20 is a substantially rectangular parallelepiped member. Each separator 20 is located between two battery cells 11 respectively.

[0024] Each battery cell 11 and each separator 20 are constrained by a constraining member (not shown). Therefore, adjacent battery cells 11 and separators 20 are in contact with each other.

[0025] Next, a plurality of metal bus bars 40 will be described. The bus bar 40 is made of a metal material such as copper which has excellent conductivity, for example.

[0026] As shown in FIGS. 3 and 4, the bus bar 40 is an integrally - formed product having a first plate - like portion 42, a second plate - like portion 46, a first rising wall portion 50, a second rising wall portion 52, and a central plate portion 54. The bus bar 40 of this embodiment is manufactured, for example, by press - forming a metal plate.

[0027] 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 whose side shape is substantially rectangular, and a downward extension portion 44 extending downward from the main body portion 43. The vertical positions of the upper edge portions of the first plate - like portion 42 and the second plate - like portion 46 are substantially the same as each other. When the bus bar 40 is in a free state, the first plate - like portion 42 and the second plate - like portion 46 are located on substantially the same plane. ​​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.

[0029] 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.

[0030] 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.

[0031] In the main transmission area 45 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, slits (first through holes) 61 are formed on the upper edge and near thereto, extending linearly along the front-rear direction in a side view. Specifically, slits 61 are also formed in the four connection portions 48, 49, 55, and 56 of the busbar 40. Connection portion 48 is the portion (ridge) connecting the main body 43 and the first rising wall 50, and connection portion 49 is the portion (ridge) connecting the first rising wall 50 and the central plate 54. Also, connection portion 55 is the portion (ridge) connecting the second plate-like portion 46 and the second rising wall 52, and connection portion 56 is the portion (ridge) connecting the second rising wall 52 and the central plate 54.

[0032] Near the lower edge of the main power transmission area 45 of 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, 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.

[0033] Furthermore, in the region below the slit 62 of 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, a slit 63 is formed that extends linearly along the front-rear direction in a side view. The side shape of the slit 63 is substantially the same as that of the slits 61 and 62.

[0034] Furthermore, as shown in Figures 3 and 4, each busbar 40 has five auxiliary slits (first auxiliary through holes) 70 that span the main body portion 43, connecting portion 48, first rising wall portion 50, connecting portion 49, and central plate portion 54. In addition, each busbar 40 has five auxiliary slits (second auxiliary through holes) 75 that span the second plate portion 46, connecting portion 55, second rising wall portion 52, connecting portion 56, and central plate portion 54. The uppermost auxiliary slits 70 and 75 are in the same vertical position and are located above slit 61. The second highest auxiliary slits 70 and 75 are in the same vertical position and are located between slit 61 and slit 62. The third highest auxiliary slits 70 and 75 are in the same vertical position and are located between slit 62 and slit 63. The fourth highest auxiliary slits 70 and 75 are in the same vertical position, and the fifth highest auxiliary slits 70 and 75 are in the same vertical position.

[0035] As is clear from Figures 3 and 4, the total length of auxiliary slits 70 and 75 is shorter than that of slits 61, 62, and 63. Also, the vertical width of slits 61, 62, and 63 and auxiliary slits 70 and 75 are substantially the same.

[0036] 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.

[0037] 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.

[0038] (Mechanism of action and effect) Next, the operation and effects of the embodiment will be described.

[0039] 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.

[0040] The connection portions 48 and 55 in each busbar 40 of this embodiment are parts that greatly affect the rigidity of the busbar 40. Furthermore, the connection portions 49 and 55 also greatly affect the rigidity of the busbar 40. Five auxiliary slits 70 and 75 are formed in the connection portions 48, 49, 55, and 56 of the busbar 40, respectively. Therefore, although the auxiliary slits 70 and 75 are smaller (shorter) than the slits 61, 62, and 63, forming the auxiliary slits 70 and 75 in these connection portions 48, 49, 55, and 56 reduces the rigidity of the busbar 40. Consequently, for example, when an external force is applied to the busbar 40 from the battery cells 11 due to vibrations during vehicle operation, or when each battery cell 11 expands and contracts, the busbar 40 can deform flexibly and absorb this external force. Therefore, in such cases, there is little risk of the first weld 58 and the second weld 60 of each busbar 40 separating from the corresponding positive terminal 13P or negative terminal 13N.

[0041] Furthermore, each auxiliary slit 70, 75 is smaller (shorter) than slits 61, 62, 63. Therefore, although some auxiliary slits 70, 75 are formed in the power transmission line 41, there is little risk of a significant increase in the electrical resistance of the busbar 40 due to each auxiliary slit 70, 75, and the heat dissipation area of ​​the busbar 40 is not significantly reduced. As a result, the busbar 40 is less likely to become overheated. In addition, electricity flows easily between the first weld 58 and the second weld 60 of each busbar 40.

[0042] 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, some of the auxiliary slits 70 and 75 are located above or below the main transmission region 45. Therefore, compared to the case where all of the auxiliary slits 70 and 75 are formed in the main transmission region 45, there is less risk of the electrical resistance of the busbar 40 becoming high.

[0043] Furthermore, the first weld 58 and the second weld 60 are located above the central position 40C of the busbar 40, and the slits 61, 62 and the two upper auxiliary slits 70, 75 are also located above the central position 40C. The opening area of ​​slits 61, 62 (63) is larger than the opening area of ​​the auxiliary slits 70, 75. Therefore, the value obtained by dividing the second total value (sum of the opening areas of slits 61, 62 and the two upper auxiliary slits 70, 75) by the first total value (sum of the opening areas of slits 61, 62, 63 and all the auxiliary slits 70, 75) is greater than 0.5 (50%). In other words, the majority of slits 61, 62, 63 and all the auxiliary slits 70, 75 are formed near the first weld 58 and the second weld 60 of the busbar 40. Therefore, compared to the case where the value obtained by dividing the second total value by the first total value is 0.5 or less, the rigidity of the peripheral parts of the first weld 58 and the second weld 60 in the bus bar 40 is reduced. As a result, compared to the case where the value obtained by dividing the second total value by the first total value is 0.5 or less, there is less risk of the first weld 58 and the second weld 60 of each bus bar 40 separating from the corresponding positive terminal 13P or negative terminal 13N when an external force is applied to the bus bar 40 from the battery cell 11.

[0044] 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.

[0045] For example, the auxiliary slits 70 and 75 may be formed only above or below the main transmission area 45.

[0046] Auxiliary slits 70 and 75 are provided in the connecting portions 48 and 55, but do not necessarily have to be provided in the connecting portions 49 and 56.

[0047] The first weld 58 and the second weld 60 may be located below the central position 40C of the busbar 40. In this case, it is preferable that the value obtained by dividing the second total value (the sum of the opening areas of the slits 61, 62, 62 and auxiliary slits 70, 75 located below the central position 40C) by the first total value (the sum of the opening areas of the slits 61, 62, 63 and all auxiliary slits 70, 75) is greater than 0.5 (50%).

[0048] The slit 63 may be omitted from the busbar 40. Alternatively, in addition to the slits 61, 62, and 63, 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 40C center position 42 First plate-like portion 46 Second plate-like portion 48 49 Connection part 50 First rising wall section 52 Second rising wall section 55 56 Connection part 58. First weld (first connection) 60. Second weld (second connection) 61 Slit (First through hole) 62 Slit (Second Through Hole) 70 Auxiliary slit (first auxiliary through hole) 75 Auxiliary slit (second auxiliary through hole)

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 plate-shaped portion including a first connecting portion connected to the terminal of one of the two battery cells, A second plate-shaped portion including a second connecting portion connected to the terminal of the other of the two battery cells, A first rising wall portion extends in the orthogonal direction from the edge of the first plate-shaped portion opposite to the second plate-shaped portion so as to move away from the battery cell, A second rising wall portion extends in the orthogonal direction from the edge of the second plate-shaped portion opposite to the first plate-shaped portion so as to move away from the battery cell, A central plate portion connecting the opposing edges of the first and second rising wall portions, 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 first auxiliary through-hole is formed at the connection between the first rising wall portion and the first plate-like portion. A bus bar having a second auxiliary through-hole formed at the connection point between the second rising wall portion and the second plate-like portion.

2. The first auxiliary through-hole is formed at the connection between the first rising wall portion and the central plate portion. The bus bar according to claim 1, wherein the second auxiliary through hole is formed at the connection between the second rising wall portion and the central plate portion.

3. The bus bar according to claim 1 or claim 2, wherein the first auxiliary through-hole and the second auxiliary through-hole are located above and below at least one of the regions 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.

4. The first and second connecting portions are located either above or below the central position in the vertical direction of the busbar. The bus bar according to claim 1 or claim 2, wherein the total opening area of ​​the first through hole, the second through hole, the first auxiliary through hole, and the portion of the second auxiliary through hole located above or below the central position is greater than 50% of the total opening area of ​​the first through hole, the second through hole, the first auxiliary through hole, and the second auxiliary through hole.

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