JP2016091959A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery pack that suppresses a rise of temperature of a bus bar for connecting a plurality of unit cells.SOLUTION: A battery pack 10 includes a plurality of unit cells 20 connected in parallel by bus bars (positive electrode bus bar 30, negative electrode bus bar 40). The bus bars include connection surfaces (upper surface 32, lower surface 42) to which the plurality of unit cells are connected and include cooling fins 33, 43 on surfaces on the sides opposite to the connection surfaces. A positive electrode coupling surface 37 of a positive electrode coupling unit 35 and a negative electrode coupling surface 47 of a negative electrode coupling unit 45 may be connected in series by welding etc.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an assembled battery. More specifically, the present invention relates to an assembled battery in which a plurality of single cells are connected by a bus bar.

  In general, when a battery is used as a power source for various purposes, it is used as an assembled battery in which a plurality of single cells are combined in order to obtain an output corresponding to the use. For example, an assembled battery used for a vehicle or the like includes a large number of single cells connected by a bus bar. In the assembled battery, when the current value of the current flowing through the circuit is high, the amount of heat generated may increase. For this reason, in an assembled battery in which a large current flows, it is important to take into consideration that the temperature does not rise too much.

  For example, Patent Document 1 discloses an assembled battery in which a plurality of cylindrical unit cells are accommodated in a single case and having a cooling unit. The cooling unit is capable of flowing a refrigerant for cooling each single cell in the case of the assembled battery. And since it is possible to keep the temperature of each unit cell at substantially the same temperature by the cooling unit, it is said that variation in cell characteristics of the unit cell can be suppressed.

JP 2012-238393 A

  By the way, in an assembled battery, heat is generated even in a bus bar connecting a plurality of single cells during charging and discharging. In addition, in an assembled battery that can be charged and discharged with a large current, the amount of heat generated in the bus bar also increases. However, in the above-described prior art, although the unit cell in the assembled battery can be cooled, the heat generation of the bus bar is not taken into consideration. Therefore, there was a risk that the temperature of the bus bar would rise too much.

  The present invention has been made for the purpose of solving the problems of the prior art described above. That is, the place made into the subject is providing the assembled battery by which the temperature rise of the bus bar which connects a several cell was suppressed.

  The assembled battery of the present invention made for the purpose of solving this problem is an assembled battery in which a plurality of single cells are connected by a bus bar, and the bus bar has a connection surface to which the plurality of single cells are connected. The battery pack has a cooling fin on the surface opposite to the connection surface.

  In the assembled battery of the present invention, the bus bar has a cooling fin on the surface opposite to the connection surface. Therefore, the temperature rise of the bus bar is suppressed by the cooling fin.

  ADVANTAGE OF THE INVENTION According to this invention, the assembled battery by which the temperature rise of the bus bar which connects a several cell was suppressed was provided.

It is a perspective view of the assembled battery which concerns on this form. It is a front view of the assembled battery which concerns on this form. It is a side view of the assembled battery which concerns on this form. It is sectional drawing of a bus bar. It is a perspective view of the assembled battery formed by connecting a plurality of assembled batteries in series. It is detail drawing which shows the terminal part of a bus-bar. It is a figure which shows the connection state of the terminal parts of a bus bar. It is detail drawing which shows the terminal part of the bus bar different from FIG. It is a figure which shows the connection state of the terminal parts of FIG.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best mode for embodying the present invention will be described in detail with reference to the drawings. Note that the drawings used in the description include portions where the thickness and shape are exaggerated from the actual ones for ease of understanding.

  In FIG. 1, the perspective view of the assembled battery 10 which concerns on this form is shown. The assembled battery 10 of this embodiment is formed by connecting a plurality of unit cells 20 by bus bars 30 and 40. Specifically, the assembled battery 10 is formed by connecting eight unit cells 20. A conductive metal can be used for the bus bars 30 and 40.

  FIG. 2 is a front view of the assembled battery 10. FIG. 3 is a side view of the assembled battery 10. As shown in FIGS. 2 and 3, the unit cell 20 of the present embodiment is of a cylindrical type. In addition, the cell 20 of this embodiment is a secondary battery that can be charged and discharged. For this reason, a lithium ion secondary battery, a nickel hydrogen rechargeable battery, or the like can be used as the unit cell 20. In the assembled battery 10 of this embodiment, all of the plurality of single cells 20 are assembled with the positive terminal 21 facing upward and the negative terminal 22 facing downward.

  As shown in FIG. 2, the bus bar 30 has a flat plate portion 31. As shown in FIG. 2, the bus bar 30 is connected to the positive terminals 21 of the plurality of unit cells 20 on the lower surface 32 of the flat plate portion 31. For this reason, the bus bar 30 is hereinafter referred to as a positive electrode bus bar 30. Moreover, the lower surface 32 of the positive electrode bus bar 30 is a connection surface to which a plurality of single cells 20 are connected.

  The bus bar 40 also has a flat plate portion 41 as shown in FIG. As shown in FIG. 2, the bus bar 40 is connected to the negative terminals 22 of the plurality of unit cells 20 on the upper surface 42 of the flat plate portion 41. For this reason, the bus bar 40 is hereinafter referred to as a negative electrode bus bar 40. The upper surface 42 of the negative electrode bus bar 40 is a connection surface to which a plurality of unit cells 20 are connected.

  Further, as shown in FIGS. 1 to 3, the positive electrode bus bar 30 has a positive electrode terminal portion 34 extending downward from the flat plate portion 31 on the outer edge thereof. As shown in FIG. 3, the positive terminal portion 34 includes a positive electrode connecting portion 35 and a connecting portion 36 connecting the positive electrode connecting portion 35 to the flat plate portion 31. The positive electrode coupling part 35 is a part protruding from the connection part 36 toward the outside of the assembled battery 10, and has a positive electrode coupling surface 37 on the side opposite to the connection part 36.

  As shown in FIGS. 1 to 3, the negative electrode bus bar 40 has a negative electrode terminal portion 44 extending upward from the flat plate portion 41 on the outer edge thereof. As shown in FIG. 3, the negative electrode terminal portion 44 includes a negative electrode connection portion 45 and a connection portion 46 that connects the negative electrode connection portion 45 to the flat plate portion 41. The negative electrode coupling portion 45 is a portion protruding from the connection portion 46 toward the outside of the assembled battery 10, and has a negative electrode coupling surface 47 on the side opposite to the connection portion 46.

  As shown in FIGS. 1 to 3, in the assembled battery 10, the plurality of single cells 20 are connected in parallel by a positive electrode bus bar 30 and a negative electrode bus bar 40. The assembled battery 10 can be charged / discharged in each unit cell 20 via the positive electrode terminal portion 34 of the positive electrode bus bar 30 and the negative electrode terminal portion 44 of the negative electrode bus bar 40.

  Further, as shown in FIGS. 1 to 3, the positive electrode bus bar 30 has cooling fins 33 composed of a plurality of convex portions on the surface of the flat plate portion 31 opposite to the lower surface 32 to which the unit cells 20 are connected. doing. Similarly, the negative electrode bus bar 40 has cooling fins 43 made up of a plurality of convex portions on the surface of the flat plate portion 41 opposite to the upper surface 42 to which the unit cells 20 are connected. That is, both the cooling fins 33 and the cooling fins 43 have a surface area larger than that of the plane and a shape with high heat dissipation.

  Here, in the battery pack 10, heat is generated in the positive electrode bus bar 30 and the negative electrode bus bar 40 when charging and discharging are performed. For this reason, in the assembled battery 10, it is preferable that the temperature rise in the positive electrode bus bar 30 and the negative electrode bus bar 40 is reduced as much as possible. This is because the battery performance of the assembled battery 10 is deteriorated due to an increase in the resistance values of the positive electrode bus bar 30 and the negative electrode bus bar 40.

  Therefore, in the assembled battery 10 of this embodiment, the positive and negative electrode bus bars 30 and 40 are provided with the cooling fins 33 and the cooling fins 43 having high heat dissipation properties as described above. For this reason, the temperature of the positive electrode bus bar 30 and the negative electrode bus bar 40 does not increase so much even during charging, and the battery performance of the assembled battery 10 is prevented from deteriorating.

  FIG. 4 is a cross-sectional view of the positive electrode bus bar 30. In FIG. 4, the thickness of the flat plate portion 31 is indicated by A. The thickness A of the flat plate portion 31 is preferably 0.4 mm or more. This is because if the thickness A of the flat plate portion 31 is 0.4 mm or more, the resistance value of the flat plate portion 31 of the positive electrode bus bar 30 is not so high.

  In FIG. 4, the height of the convex portion in the cooling fin 33 is indicated by B, and the width of the convex portion in the cooling fin 33 is indicated by C. Further, in FIG. 4, an interval between adjacent convex portions in the cooling fin 33 is indicated by D. In the present embodiment, the height B of the cooling fin 33 is preferably in the range of 0.4 mm or more and 0.8 mm or less. In addition, for the cooling fin 33, both the width C and the interval D are preferably in the range of 5 mm or more and 150 mm or less. The preferable ranges of the width C and the interval D are the same in the depth direction in FIG.

  And heat dissipation in the positive electrode bus bar 30 can be favorably performed by setting the height B, width C, and interval D of the cooling fins 33 within the above ranges. Specifically, by making the shape of the cooling fin 33 within the above range, the temperature of the positive electrode bus bar 30 at the time of charging / discharging is compared with that of only the flat plate portion 31 where the cooling fin 33 is not provided. Can be lowered by about 10 ° C. FIG. 4 shows the positive bus bar 30, but the negative bus bar 40 can have the same shape.

  Moreover, the assembled battery 10 of this embodiment can be further connected to form an assembled battery. FIG. 5 is a perspective view of an assembled battery 90 formed by connecting three assembled batteries 10. In the assembled battery 90, the adjacent assembled batteries 10 are connected in series by the positive electrode terminal portion 34 and the negative electrode terminal portion 44. Therefore, the assembled battery 90 can be charged and discharged via the positive terminal portion 34 of the leftmost assembled battery 10 and the negative terminal portion 44 of the rightmost assembled battery 10 in FIG.

  FIG. 6 is a detailed view of the positive terminal portion 34 of this embodiment. As shown in FIG. 6, the positive terminal portion 34 of this embodiment is formed by bending a sheet metal. That is, in the positive electrode terminal portion 34 of this embodiment, the positive electrode coupling portion 35 is formed by bending the tip of the connection portion 36 as shown in FIG. In FIG. 6, E represents the area of the positive electrode connection surface 37 of the positive electrode connection portion 35 formed by bending.

  Further, in the positive electrode terminal portion 34 of the present embodiment, as shown in FIG. 6, the connecting portion 36 has a portion 38 formed wider than the width F of the connecting portion 36 toward the inside in the width direction of the connecting portion 36. It is formed by bending. Accordingly, the positive terminal portion 34 of the present embodiment has a small width F of the connecting portion 36. Furthermore, the thickness of the connecting portion 36 formed by bending the wide portion 38 is greater than the thickness of one sheet. Although FIG. 6 shows the positive terminal portion 34, the negative terminal portion 44 has the same shape.

  FIG. 7 is a diagram showing a connection state between the positive terminal portion 34 and the negative terminal portion 44 in the present embodiment. The positive electrode terminal portion 34 and the negative electrode terminal portion 44 are joined by welding in a state where the positive electrode connection surface 37 and the negative electrode connection surface 47 are combined.

  In this embodiment, when the positive electrode terminal portion 34 and the negative electrode terminal portion 44 are welded, the positive electrode connecting surface 37 and the negative electrode connecting surface 47 are made thicker in a state where the positive electrode connecting surface 37 and the negative electrode connecting surface 47 are combined. It can be easily sandwiched by a processing jig for welding in the vertical direction. In this embodiment, as described above, both the positive electrode connecting portion 35 and the negative electrode connecting portion 45 are formed so as to protrude toward the outside of the assembled battery 10. For this reason, a sufficient space is provided around the positive electrode connecting portion 35 and the negative electrode connecting portion 45 for allowing a processing jig for welding to approach.

  In this embodiment, the positive terminal portion 34 and the negative terminal portion 44 are welded by ultrasonic welding. In ultrasonic welding, thicker plates can be joined than resistance welding. For this reason, as the positive electrode terminal part 34 and the negative electrode terminal part 44, a thing with thick plate | board thickness can be used. In this embodiment, the cross-sectional area is increased by using the positive electrode terminal portion 34 and the negative electrode terminal portion 44 having a large plate thickness. Thereby, the resistance value in the positive electrode terminal part 34 and the negative electrode terminal part 44 at the time of charging / discharging is reduced.

  Further, in the positive electrode terminal portion 34 of the present embodiment, as described with reference to FIG. 6, a process of bending the wide portion 38 of the connection portion 36 inward is performed. This also applies to the negative electrode terminal portion 44. For this reason, both the positive electrode terminal portion 34 and the negative electrode terminal portion 44 have a large cross-sectional area at the connection portions 36 and 46 while keeping the width of the connection portions 36 and 46 small. Therefore, the widths of the connecting portions 36 and 46 are kept small, and the resistance values at the positive electrode terminal portion 34 and the negative electrode terminal portion 44 during charging and discharging are reduced.

  Therefore, the assembled battery 90 has good charge / discharge performance due to the low resistance values of the positive electrode terminal portion 34 and the negative electrode terminal portion 44 connected to each assembled battery 10. That is, the assembled battery 90 is of high quality. Furthermore, the positive electrode terminal portion 34 is prevented from generating heat due to the reduced resistance value. For this reason, the positive electrode bus bar 30 is also restrained from an increase in temperature at the positive electrode terminal portion 34. Similarly, the negative terminal portion 44 has a reduced resistance value, thereby suppressing heat generation. For this reason, also about the negative electrode bus bar 40, the temperature rise in the negative electrode terminal part 44 is also suppressed.

  Moreover, it is preferable that the joint area of the positive electrode terminal part 34 and the negative electrode terminal part 44 is sufficiently large. This is because when the area of the joining portion is small, the resistance value at that portion becomes high. In the positive electrode terminal portion 34 of this embodiment, as described in FIG. 6, the positive electrode connecting portion 35 is formed by bending. For this reason, the area E of the positive electrode connection surface 37 of the positive electrode connection part 35 can be taken sufficiently. This also applies to the negative electrode terminal portion 44.

  Therefore, the area of the positive electrode connection surface 37 and the negative electrode connection surface 47 can be made sufficiently large at the joint portion between the positive electrode terminal portion 34 and the negative electrode terminal portion 44 of this embodiment, and the resistance value at the joint portion is reduced. can do. For this reason, an increase in temperature is also suppressed at the joint portion between the positive electrode terminal portion 34 and the negative electrode terminal portion 44. Further, by increasing the areas of the positive electrode connecting surface 37 and the negative electrode connecting surface 47, the bonding strength is also sufficient.

  In addition, the positive electrode bus bar 30 can be manufactured by integrating the flat plate portion 31, the cooling fin 33, and the positive electrode terminal portion 34 by sheet metal processing. In other words, the cooling fins 33 can be formed by press working that presses a mold having irregularities on the surface opposite to the lower surface 32 of the positive electrode bus bar 30. Similarly, the negative electrode bus bar 40 can be manufactured by integrating the flat plate portion 41, the cooling fins 43, and the negative electrode terminal portion 44 by sheet metal processing. And when manufacturing the positive electrode bus bar 30 and the negative electrode bus bar 40 by sheet metal processing, it is preferable to carry out escape processing necessary for bending the sheet metal in an appropriate place.

  Further, when the assembled battery 10 is for in-vehicle use such as PHV and the positive electrode bus bar 30 and the negative electrode bus bar 40 are manufactured by sheet metal processing, the thickness of the metal plate to be used should be at least 0.4 mm or more. It is preferable to use it. In the battery pack 10 for consumer use that has a lower current than that for in-vehicle use, a metal plate having a thickness of 0.15 mm or 0.2 mm can be used. Furthermore, when cost is considered, it is preferable to use a metal plate having a thickness of 0.8 mm or less. When the battery pack 10 is for in-vehicle use and a high current flows, the thickness of the flat plate portion 31 is increased while the resistance value is reduced while the plate thickness is 1 as a metal plate. It is conceivable to use a 2 mm or 2 mm one.

  FIG. 8 shows a positive electrode terminal portion 134 which is a modified example of this embodiment. The positive electrode terminal portion 134 can also be formed by bending a sheet metal, like the positive electrode terminal portion 34 described above. Moreover, the positive electrode terminal part 134 has the positive electrode connection part 135 located in the front-end | tip. Also in the positive electrode terminal part 134, the opposite side of the connection part 136 to the positive electrode connection part 135 is connected to the flat plate part of the positive electrode bus bar. Furthermore, the positive electrode connection part 135 is a part formed so as to protrude on the opposite side to the assembled battery.

  Also in the positive electrode terminal portion 134 shown in FIG. 8, one surface of the positive electrode connecting portion 135 is a positive electrode connecting surface 137. In FIG. 8, the area of the positive electrode connection surface 137 is indicated by G. Further, the connection portion 136 is also formed by bending a metal plate formed wider than its width H. For this reason, also in the connection part 136, the cross-sectional area is enlarged, keeping the width H small. Therefore, by using the positive electrode terminal portion 134 shown in FIG. 8, the resistance value can be lowered, so that heat generation in the positive electrode terminal portion 134 can be suppressed.

  FIG. 9 is a diagram illustrating a connection state of the positive terminal portion 134 illustrated in FIG. 8 and the negative terminal portion 144. The negative electrode terminal portion 144 shown in FIG. 9 is also formed by bending similar to the positive electrode terminal portion 134. Thus, the negative electrode terminal portion 144 is formed in a shape such that the negative electrode connection surface 147 is aligned with the positive electrode connection surface 137 of the positive electrode terminal portion 134.

  Then, welding of the positive electrode terminal portion 134 and the negative electrode terminal portion 144 shown in FIG. 9 is performed while sandwiching the positive electrode connecting portion 135 and the negative electrode connecting portion 145 in the thickness direction by a processing jig for welding. Can do. The sandwiching can be easily performed. Both the positive electrode connecting portion 135 and the negative electrode connecting portion 145 are formed so as to protrude toward the outside of the assembled battery. For this reason, a sufficient space is provided around the positive electrode connecting portion 135 and the negative electrode connecting portion 145 for allowing a processing jig for welding to approach.

  Further, the connecting portions 136 and 146 of the positive terminal portion 134 and the negative terminal portion 144 are both formed by bending as shown in FIG. For this reason, both the connection parts 136 and 146 have a large cross-sectional area at the connection parts 136 and 146 while keeping the width small. Therefore, the widths of the connecting portions 136 and 146 are kept small, and the resistance values at the positive electrode terminal portion 134 and the negative electrode terminal portion 144 during charging and discharging are reduced. Therefore, the temperature rise is also suppressed for the positive terminal portion 134 and the negative terminal portion 144.

  Furthermore, the area G of the positive electrode connection surface 137 of the positive electrode connection part 135 formed by bending can be made sufficiently large. The same applies to the negative electrode connecting surface 147 of the negative electrode connecting portion 145. Therefore, since the area of the joining portion between the positive electrode terminal portion 134 and the negative electrode terminal portion 144 can be made sufficiently large, an increase in temperature can be suppressed and sufficient joining strength can be obtained. Further, the welding of the positive electrode terminal portion 134 and the negative electrode terminal portion 144 can also be performed by ultrasonic welding, so that a material with a large plate thickness can be used, so that the temperature rise can be further suppressed.

  As described above in detail, the assembled battery 10 according to the present embodiment is formed by connecting a plurality of single cells 20 in parallel by the positive electrode bus bar 30 and the negative electrode bus bar 40. The positive electrode bus bar 30 has cooling fins 33 on the surface opposite to the lower surface 32 to which the unit cells 20 are connected. The negative electrode bus bar 40 has cooling fins 43 on the surface opposite to the upper surface 42 to which the unit cells 20 are connected. Therefore, an assembled battery in which the temperature rise of the bus bar connecting the plurality of single cells is suppressed is realized.

  Note that this embodiment is merely an example, and does not limit the present invention. Accordingly, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, in the above-described embodiment, the positive electrode bus bar 30 and the negative electrode bus bar 40 are described as being integrally manufactured by sheet metal processing. However, for example, the positive electrode bus bar 30 may be manufactured by integrating the flat plate portion 31 and the positive electrode terminal portion 34 by sheet metal processing. That is, the cooling fin 33 may be joined to the surface opposite to the lower surface 32 of the flat plate portion 31 by welding or the like. The same applies to the negative electrode bus bar 40.

  Further, for example, the unit cell 20 is not limited to a cylindrical type, and may be a rectangular type. Further, for example, the number of unit cells 20 in the assembled battery 10 is merely an example. That is, the number of unit cells 20 in the assembled battery 10 may be any number that can obtain an output according to the application, and may be 7 or less, or 9 or more.

10 assembled battery 20 single cell 30 positive electrode bus bar 31 flat plate portion 32 lower surface 33 cooling fin 34 positive electrode terminal portion 40 negative electrode bus bar 41 flat plate portion 42 upper surface 43 cooling fin 44 negative electrode terminal portion

Claims (1)

In an assembled battery in which multiple cells are connected by a bus bar,
The bus bar has a connection surface to which the plurality of unit cells are connected, and a cooling fin on a surface opposite to the connection surface.

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