Bus bar module

Abstract

To provide a bus bar module excellent in assemblability to a battery assembly and followability to deformation and manufacturing variations of the battery assembly.SOLUTION: A bus bar module 10 to be attached to a battery assembly 1 includes a circuit body 20 formed of a flexible substrate and a bus bar 30 connected to each of electrodes 4 and 5 of a plurality of unit cells 2. The circuit body 20 includes a main line 21 disposed so as to extend along a stacking direction of the unit cells 2, a branch line 22 branched from the main line 21 so as to extend toward the bus bar 30 and including an absorption part 23 extending along the stacking direction, and a terminal part 25 provided at a position of the branch line 22 on the terminal side of the absorption part 23 and attached to the bus bar 30. The branch line 22 has a shape folded back toward the main line 21 so that at least a part of the branch line 22 overlaps the main line 21 in the thickness direction of the main line 21.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a busbar module. [Background technology]

[0002] BACKGROUND ART Busbar modules have conventionally been used by being assembled into battery assemblies (battery modules in which a plurality of battery cells are stacked) that serve as driving power sources mounted on electric vehicles, hybrid vehicles, and the like.

[0003] For example, one conventional busbar module includes multiple busbars that are stacked and connect the positive and negative electrodes of adjacent battery cells, and voltage detection wires that are connected to each of the multiple busbars. The voltage detection wires are configured to bundle multiple electric wires that have a general structure in which core wires are covered with an insulating coating (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-220128 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, battery cells constituting a battery assembly expand and contract in the stacking direction due to operating heat generated during charging and discharging, the temperature of the external environment, and other factors. As a result, the battery assembly also deforms by expanding and contracting in the stacking direction of the battery cells. Furthermore, due to assembly tolerances when stacking multiple battery cells, the size of the battery assembly in the stacking direction generally varies from one manufactured battery assembly to another (i.e., manufacturing variations may occur). Therefore, busbar modules are generally designed to have a certain amount of leeway in the length of the voltage detection wires to accommodate such deformation of the battery assembly and manufacturing variations.

[0006] However, in the conventional busbar module described above, if the number of stacked battery cells is increased for the purpose of increasing the capacity of the battery assembly, for example, the number of electric wires constituting the voltage detection line also increases. As a result, if the voltage detection line is formed by bundling these many electric wires, the rigidity of the voltage detection line as a whole (and therefore the rigidity of the busbar module) increases, which may make it difficult for the busbar module to expand and contract sufficiently to accommodate deformation of the battery assembly and manufacturing variations.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a busbar module that is excellent in adaptability to deformation of a battery assembly and manufacturing variations. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the bus bar module according to the present invention has the following features.

[0009] A busbar module to be attached to a battery assembly in which a plurality of cells are stacked, a circuit body formed of a flexible substrate on which a wiring pattern is provided, and a bus bar to be connected to each electrode of the plurality of unit cells, The circuit body is a main line that is arranged to extend along the stacking direction of the plurality of unit cells; a branch wire branching from the main wire and extending toward the bus bar, the branch wire having a portion extending along the stacking direction as at least a part of the branch wire; a terminal portion provided on the branch line at a location closer to the end than the portion and attached to the bus bar, The branch line is At least a part of the branch wire has a shape folded back toward the main wire so as to overlap with the main wire in the thickness direction of the main wire. It is a busbar module. [Effects of the Invention]

[0010] According to the busbar module of the present invention, a circuit body made of a flexible substrate includes a main wire and a branch wire branching from the main wire. At least a portion of the branch wire has a portion (an absorbing portion, described below) that extends in the stacking direction of the unit cells. Furthermore, the branch wire has a shape in which at least a portion of the branch wire is folded back toward the main wire so as to overlap the main wire in the thickness direction of the main wire. Therefore, when the battery assembly expands or contracts in the stacking direction due to thermal deformation of each unit cell, the branch wire deforms around the absorbing portion of the branch wire of the circuit body and its surroundings, allowing each bus bar to move in the stacking direction of the unit cells. Similarly, the busbar module can absorb size variations in the stacking direction of the battery assembly due to assembly tolerances of the unit cells. In other words, the busbar module of this configuration does not require any deformation of the main wire of the circuit body; essentially, only the branch wire deforms, making it easy to accommodate expansion and contraction of the battery assembly and manufacturing variations. Furthermore, because the branch wires are folded back toward the main wire so as to overlap the main wire in the thickness direction of the main wire, the width of the circuit body can be reduced compared to when the branch wires simply extend from the main wire. Furthermore, flexible substrates generally flexibly deform with much less force than the wires used in the conventional busbar modules described above, even when incorporating multiple circuit structures. Therefore, the busbar module of the present invention is highly adaptable to deformations of the battery assembly and manufacturing variations.

[0011] The present invention has been briefly described above. The details of the present invention will become more apparent from the detailed description of the invention set forth below, taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view showing a circuit body and bus bars that constitute a bus bar module according to an embodiment of the present invention, and a battery assembly to which the bus bar module is attached. FIG. [Figure 2] 2 is a top view showing the state before the branch wire is folded back in the circuit body shown in FIG. 1.

[0023] FIG. [Figure 3]3 is a top view showing a state in which the branch wire is folded back in the circuit body shown in FIG. 2.

[0023] FIG. [Figure 4] FIG. 10 is a top view showing a state before the branch wire is folded back in the circuit body according to the first modified example. [Figure 5] 5 is a top view showing a state in which the branch wire is folded back in the circuit body shown in FIG. 4. FIG. [Figure 6] FIG. 10 is a top view showing a state in which a branch wire is folded back in a circuit body according to a second modified example. [Figure 7] FIG. 11 is a top view showing a state in which a branch wire is folded back in a circuit body according to a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Embodiment> Hereinafter, a busbar module 10 according to an embodiment of the present invention will be described with reference to the drawings. The busbar module 10 according to this embodiment is used by being assembled into a battery assembly (a battery module in which a plurality of cells are stacked) as a driving power source mounted on, for example, an electric vehicle or a hybrid vehicle.

[0014] For ease of explanation, the following definitions are used for the "front-rear direction," "up-down direction," "left-right direction," "front," "rear," "up," "down," "left," and "right" as shown in FIG. 1 etc. The "front-rear direction," "up-down direction," and "left-right direction" are perpendicular to one another. The front-rear direction coincides with the "stacking direction of the plurality of unit cells" of the present invention, and the up-down direction coincides with the "thickness direction of the main line" of the present invention.

[0015] First, a battery assembly 1 to which a busbar module 10 of this embodiment is attached will be described. As shown in Fig. 1, the battery assembly 1 is configured by connecting a plurality of unit cells 2 in series. Each of the unit cells 2 has a battery body (body) 3 formed in a rectangular parallelepiped shape, and a positive electrode 4 and a negative electrode 5 protruding from the upper part of the battery body 3. The positive electrode 4 and the negative electrode 5 are arranged apart from each other on an electrode surface 6 of the battery body 3, and each protrudes in a cylindrical shape approximately vertically upward from the electrode surface 6.

[0016] The battery assembly 1 is arranged by stacking the cells 2 in the front-to-rear direction (stacking direction) so that the positive electrodes 4 and negative electrodes 5 of adjacent cells 2 alternate. In this battery assembly 1, for example, of the cells 2 corresponding to both ends of the series-connected cells 2, the positive electrode 4 of one cell 2 serves as the overall positive electrode, and the negative electrode 5 of the other cell 2 serves as the overall negative electrode.

[0017] Next, the busbar module 10 of this embodiment will be described. As shown in Fig. 1, the busbar module 10 has a circuit body 20 made of a flexible printed circuit (so-called FPC), and busbars 30 connected to the positive electrodes 4 and negative electrodes 5 of the plurality of single cells 2. The busbar module 10 may have a resin holder (not shown) for accommodating and holding the circuit body 20 and for attaching it to the battery assembly 1.

[0018] As shown in Fig. 1, the circuit body 20 has a strip-shaped main line 21 arranged on each cell 2 in the stacking direction and provided with a plurality of wiring patterns. A connector (not shown) is attached to the end of the main line 21 in the longitudinal direction (front-rear direction, which in this example substantially coincides with the "stacking direction" of the battery assembly 1) via a voltage detection line (not shown) drawn out from the main line 21. This connector is connectable to a voltage detection device (not shown).

[0019] A band-shaped branch wire 22 extends from each of a plurality of locations on the side edge of the main wire 21 along its longitudinal direction. In FIG. 1, one of the branch wires 22 extending from each of the locations is representatively shown. The main wire 21 and the branch wire 22 are made of FPC. Therefore, the main wire 21 and the branch wire 22 are flexibly deformable, particularly in the direction perpendicular to their respective surfaces.

[0020] As shown in FIG. 2 , before being folded back as described below, the branch wire 22 extends from a side end of the main wire 21 in a region outside the side end of the main wire 21 in the width direction (left-right direction) while bending so as to have a generally U-shaped shape that opens toward the main wire 21 when viewed from the top-bottom direction. The branch wire 22 includes an absorbing portion 23 that extends in the longitudinal direction of the main wire 21 (i.e., the stacking direction of the battery assembly 1). Therefore, when the branch wire 22 deforms around the absorbing portion 23, the end portion 24 of the branch wire 22 can move relative to the main wire 21 in the longitudinal direction of the main wire 21 (i.e., the stacking direction of the battery assembly 1). A metal terminal portion 25 is connected to the end portion 24 of the branch wire 22 (a portion distal to the absorbing portion 23). In this embodiment, the terminal portion 25 is a rectangular, flat metal plate. The terminal portion 25 is electrically connected to the voltage detection line drawn from the main line 21 via a wiring pattern in the branch line 22 and a wiring pattern in the main line 21. In this example, one absorbing portion 23 is provided on the branch line 22.

[0021] 1 and 3, in this embodiment, the branch wire 22 shown in Fig. 2 is folded back toward the front side (upper side) of the main wire 21 so that almost the entire branch wire 22 overlaps with the main wire 21 in the thickness direction (vertical direction) of the main wire 21 (so that almost the entire branch wire 22 is located within the area occupied by the main wire 21 when viewed from the vertical direction). As a result, the terminal portion 25 is arranged to protrude outward in the width direction (left and right direction) from the side end of the main wire 21.

[0022] As shown in FIG. 1 , the busbar 30 integrally includes a busbar body 31, which is a flat, electrically conductive (e.g., copper) member having an overall rectangular shape, and a connection piece 32 that protrudes from the busbar body 31 toward the main wire 21. The busbar body 31 is provided with two electrode holes 33, 33 through which the positive electrode 4 and the negative electrode 5 of an adjacent cell 2 are respectively passed. A terminal portion 25 provided at the end portion 24 of the branch wire 22 is connected to the upper surface of the connection piece 32 of the busbar 30. That is, as the branch wire 22 deforms around the absorbing portion 23, the busbar 30 connected to the terminal portion 25 provided at the end portion 24 of the branch wire 22 becomes movable relative to the main wire 21 in the longitudinal direction of the main wire 21 (i.e., the stacking direction of the battery assembly 1).

[0023] When the busbar module 10 having the above configuration is attached to the battery assembly 1, even if the relative positions of the battery assembly 1 and the circuit body 20 change due to, for example, deformation of the battery assembly 1, causing a change in the relative position between the main wire 21 and the busbar 30 in the stacking direction of the battery assembly 1, the change (misalignment) in the relative position can be absorbed by deformation of the branch wire 22 centered on the absorbing section 23. Similarly, even if the size of the battery assembly 1 in the stacking direction varies among manufactured battery assemblies 1 due to assembly tolerances of the multiple cells 2, the manufacturing variation can be absorbed by deformation of the branch wire 22 centered on the absorbing section 23. Furthermore, because the branch wire 22 has a shape that is folded back toward the main wire 21 so as to overlap with the main wire 21 in the thickness direction of the main wire 21, the size of the circuit body 20 in the width direction can be reduced.

[0024] <Actions and Effects> As described above, in the busbar module 10 according to this embodiment, the circuit body 20 made of a flexible substrate includes a strip-shaped main wire 21 and strip-shaped branch wires 22 branching from the main wire 21. At least a portion of the branch wire 22 includes an absorbing portion 23 extending along the stacking direction of the battery assembly 1 and is folded back toward the main wire 21 so as to overlap the main wire 21 in the thickness direction of the main wire 21. Therefore, when the battery assembly 1 expands or contracts in the stacking direction due to thermal deformation of each battery cell 2, the branch wire 22 of the circuit body 20 deforms around the absorbing portion 23 of the branch wire 22, thereby allowing each busbar 30 to move in the stacking direction of the battery cells 2. Similarly, size variations in the stacking direction of the battery assembly 1 caused by assembly tolerances of the battery cells 2 can be accommodated. In other words, the busbar module 10 according to this embodiment does not require any deformation of the main wires 21 of the circuit body 20, and substantially only the branch wires 22 deform, thereby easily adapting to expansion and contraction of the battery assembly 1 and manufacturing variations. Furthermore, because the branch wires 22 are folded back toward the main wires 21 so as to overlap with the main wires 21 in the thickness direction of the main wires 21, the width of the circuit body 20 can be reduced. Furthermore, flexible substrates generally flexibly deform with much less force than the electric wires used in the conventional busbar modules described above, even when multiple circuit structures are incorporated. This significantly improves the ease of assembling the busbar module 10 to the battery assembly 1.

[0025] <Other aspects> It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be adopted within the scope of the present invention. For example, the present invention is not limited to the above-described embodiments, and modifications, improvements, etc. are possible as appropriate. Furthermore, the material, shape, dimensions, number, location, etc. of each component in the above-described embodiments are arbitrary as long as they can achieve the present invention, and are not limited thereto.

[0026] For example, in the above embodiment, before being folded back, as shown in Figure 2, the branch wire 22 extends from the side end of the main wire 21 in a widthwise outer region from the side end of the main wire 21, bending so as to have an approximately U-shaped shape that opens toward the main wire 21 when viewed from the top and bottom, and the branch wire 22 shown in Figure 2 is folded back toward the front side (upper side) of the main wire 21 so that almost the entire branch wire 22 overlaps with the main wire 21 in the thickness direction of the main wire 21, as shown in Figure 3.

[0027] In contrast, in a first modified example shown in FIGS. 4 and 5 , before being folded back, the branch wire 22 extends in the longitudinal direction of the main wire 21 while bending from the side end of the main wire 21 in a region outside the side end of the main wire 21 in the width direction, forming a substantially S-shaped curve when viewed from the up-down direction, as shown in FIG. 4 . The branch wire 22 shown in FIG. 4 is folded back toward the front side (upper side) of the main wire 21 so that almost the entire branch wire 22 overlaps with the main wire 21 in the thickness direction of the main wire 21, as shown in FIG. 5 . As a result, the terminal portion 25 is arranged to protrude outward in the width direction (left-right direction) from the side end of the main wire 21. In the first modified example, the branch wire 22 includes an absorbing portion 23 that extends in the longitudinal direction of the main wire 21. In this example, two absorbing portions 23 are provided in the branch wire 22. This allows the branch wires 22 to more efficiently absorb expansion and contraction of the battery assemblies 1 in the stacking direction and variations in size of the battery assemblies 1 in the stacking direction due to assembly tolerances.

[0028] Furthermore, in the second modified example shown in Figure 6, as in the above embodiment, before being folded back, the branch wire 22 extends from the side end of the main wire 21 in a widthwise outer region from the side end of the main wire 21, as shown in Figure 2, while bending so as to have an approximately U-shaped shape that opens toward the main wire 21 when viewed from the top and bottom, and the branch wire 22 shown in Figure 2 is folded back toward the back side (bottom side) of the main wire 21 so that almost the entire branch wire 22 overlaps with the main wire 21 in the thickness direction of the main wire 21, as shown in Figure 6.

[0029] Furthermore, in the third modified example shown in Figure 7, similar to the first modified example described above, before being folded back, the branch wire 22 extends in the longitudinal direction of the main wire 21, as shown in Figure 4, in the widthwise outer region from the side end of the main wire 21, while bending so as to have an approximately S-shaped shape when viewed from the top and bottom, and the branch wire 22 shown in Figure 4 is folded back toward the back side (bottom side) of the main wire 21 so that almost the entire branch wire 22 overlaps with the main wire 21 in the thickness direction of the main wire 21, as shown in Figure 7.

[0030] The first to third modified examples can also achieve the same effects as those of the above embodiment.

[0031] Here, the features of the embodiment of the busbar module 10 according to the present invention described above will be briefly summarized and listed below in [1] to [2].

[0032] [1] A busbar module (10) to be attached to a battery assembly (1) in which a plurality of unit cells (2) are stacked, a circuit body (20) made of a flexible substrate on which a wiring pattern is provided, and a bus bar (30) to be connected to each of the electrodes (4, 5) of the plurality of single cells (2), The circuit body (20) is a main line (21) that is arranged to extend along the stacking direction of the plurality of unit cells (2); a branch wire (22) branching from the main wire (21) and extending toward the bus bar (30), the branch wire (22) having a portion (23) extending along the stacking direction as at least a part of the branch wire (22); a terminal portion (25) provided at a location on the branch line (22) closer to the end than the portion (23) and attached to the bus bar (30), The branch line (22) At least a part of the branch wire (22) is folded back toward the main wire (21) so as to overlap with the main wire (21) in the thickness direction of the main wire (21). Busbar module (10).

[0033] In the busbar module having the above configuration, the circuit body made of a flexible substrate includes a main wire and a branch wire branching from the main wire. At least a portion of the branch wire has a portion (an absorbing portion, described below) that extends in the stacking direction of the unit cells. Furthermore, the branch wire has a shape in which at least a portion of the branch wire is folded back toward the main wire so as to overlap the main wire in the thickness direction of the main wire. Therefore, when the battery assembly expands or contracts in the stacking direction due to thermal deformation of each unit cell, the branch wire deforms around the absorbing portion of the branch wire of the circuit body and its surroundings, allowing each bus bar to move in the stacking direction of the unit cells. Similarly, the busbar module can absorb size variations in the stacking direction of the battery assembly due to assembly tolerances of the unit cells. In other words, the busbar module having this configuration does not require any deformation of the main wire of the circuit body, and essentially only the branch wire deforms, making it easy to accommodate expansion and contraction of the battery assembly and manufacturing variations. Furthermore, because the branch wires are folded back toward the main wire so as to overlap the main wire in the thickness direction of the main wire, the width of the circuit body can be reduced compared to when the branch wires simply extend from the main wire. Furthermore, flexible substrates generally flexibly deform with much less force than the wires used in the conventional busbar modules described above, even when incorporating multiple circuit structures. Therefore, the busbar module of this configuration is highly adaptable to deformations of the battery assembly and manufacturing variations.

[0034] [2] In the busbar module (10) described in [1] above, The branch line (22) The branch line (22) has the portions (23) at multiple locations. Busbar module (10).

[0035] According to the busbar module having the configuration [2] above, the branch wire of the circuit body has a plurality of the aforementioned portions (i.e., absorbing portions), which allows the branch wire to more efficiently absorb expansion and contraction in the stacking direction of the battery assembly caused by thermal deformation of each cell, and size variations in the stacking direction of the battery assembly caused by assembly tolerances of the cells. [Explanation of symbols]

[0036] 1 battery assembly 2 D cells 4 Positive electrode 5. Negative electrode 10 Busbar module 20 Circuit body 21 Main Line 22 branch line 23 Absorption section (part) 25 Terminal section 30 Bus Bar

Claims

1. A busbar module to be attached to a battery assembly in which a plurality of cells are stacked, a circuit body formed of a flexible substrate on which a wiring pattern is provided, and a bus bar to be connected to each electrode of the plurality of unit cells, The circuit body is a main line that is arranged to extend along the stacking direction of the plurality of unit cells; a branch wire branching from the main wire and extending toward the bus bar, the branch wire having a portion extending along the stacking direction as at least a part of the branch wire; a terminal portion provided on the branch line at a location closer to the end than the portion and attached to the bus bar, The branch line is At least a part of the branch wire has a shape folded back toward the main wire so as to overlap with the main wire in the thickness direction of the main wire. Busbar module.

2. The busbar module according to claim 1, The branch line is The branch line has the portion at a plurality of locations. Busbar module.

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