Voltage monitoring module and battery unit

Abstract

To provide a voltage monitoring module and a battery unit having a structure in which a connection terminal can excellently follow the movement of a corresponding cell terminal with contraction or expansion of a battery cell.SOLUTION: A voltage monitoring module 100 monitors a voltage state of a battery pack 200 in which a plurality of sections 250 each having a plurality of battery cells 210 stacked in a first direction are arranged in the first direction, and includes a plurality of flexible printed boards 10 corresponding to the plurality of sections 250. Each of the plurality of flexible printed boards 10 includes a main body portion 11, and a plurality of branch portions 20 intermittently arranged in the first direction. The branch portion 20 has a connection terminal 55. The connection terminal 55 of the branch portion 20 of each flexible printed board 10 is connected to a cell terminal 220 of the battery cell 210 of the section 250 corresponding to the flexible printed board 10.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a voltage monitoring module and a battery unit. [Background technology]

[0002] Patent Document 1 describes a voltage monitoring module (described in the document as a busbar module) that monitors the voltage state of a battery pack (described in the document as a battery assembly) comprising a plurality of stacked battery cells (described in the document as single cells), the voltage monitoring module including a flexible printed circuit board (described in the document as a flexible circuit board) having a plurality of wirings, the flexible printed circuit board including a main body portion (described in the document as a main line) extending in a first direction and a plurality of branch portions (described in the document as branch lines) each branching off from the main body portion and arranged intermittently in the first direction, the flexible printed circuit board corresponding to the entire battery pack, and connection terminals of the branch portions of the flexible printed circuit board being connected to cell terminals of all battery cells in the battery pack. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-013766 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to the investigations of the present inventors, there is room for improvement in the technique of Patent Document 1 in terms of enabling the connection terminals to better follow the movement of the corresponding cell terminals as the battery cells contract or expand.

[0005] The present invention has been made in consideration of the above-mentioned problems, and provides a voltage monitoring module and a battery unit in which the connection terminals can closely follow the movement of the corresponding cell terminals as the battery cells contract or expand. [Means for solving the problem]

[0006] According to the present invention, there is provided a voltage monitoring module for monitoring a voltage state of a battery pack in which a plurality of compartments, each of which has a plurality of battery cells stacked in a first direction, are arranged in the first direction, the voltage monitoring module comprising: a plurality of flexible printed circuit boards each corresponding to one of the plurality of sections; Each of the plurality of flexible printed circuit boards is A main body portion extending in the first direction; A plurality of branch portions each branching from the main body portion and arranged intermittently in the first direction; Equipped with the branch portion has a connection terminal at a tip end portion thereof that is connected to a cell terminal that is a terminal of the battery cell, A voltage monitoring module is provided such that the connection terminals of the branched portions of each flexible printed circuit board are connected to the cell terminals of the battery cells in the section corresponding to that flexible printed circuit board.

[0007] According to the present invention, there is also provided a voltage monitoring module according to the present invention, The battery pack; Equipped with A battery unit is provided in which each connection terminal of the flexible printed circuit board is connected to a corresponding one of the cell terminals of the battery pack. Effect of the Invention

[0008] According to the present invention, the connection terminal can smoothly follow the movement of the corresponding cell terminal as the battery cell contracts or expands. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a perspective view of the battery unit according to the first embodiment. [Diagram 2] FIG. 2 is a plan view of the battery unit according to the first embodiment. [Diagram 3] FIG. 2 is a plan view of the voltage monitoring module in the first embodiment. [Figure 4] Figures 4(a) and 4(b) are plan views of the battery pack according to the first embodiment, in which Figure 4(a) shows the state of the battery pack when discharging, and Figure 4(b) shows the state of the battery pack when charging. [Diagram 5] FIG. 2 is a perspective view showing an expansion / contraction section and its surrounding structure in the first embodiment. [Figure 6] 6(a) and 6(b) are partial enlarged views of the connection terminal and its surrounding structure in the first embodiment, with FIG. 6(a) being a perspective view and FIG. 6(b) being a plan view. [Figure 7] Figures 7(a) and 7(b) are side views showing the expansion / contraction section and its surrounding structure in the first embodiment, where Figure 7(a) shows the state when the battery pack is discharging and Figure 7(b) shows the state when the battery pack is charging. [Figure 8] Figures 8(a) and 8(b) are side views showing the expansion / contraction portion and its surrounding structure in variant example 1 of the first embodiment, where Figure 8(a) shows the state of the battery pack when discharging, and Figure 8(b) shows the state of the battery pack when charging. [Figure 9] Figures 9(a) and 9(b) are side views showing the expansion / contraction portion and its surrounding structure in variant example 2 of the first embodiment, where Figure 9(a) shows the state of the battery pack when discharging, and Figure 9(b) shows the state of the battery pack when charging. [Figure 10] 13 is a plan view of a battery unit according to a third modified example of the first embodiment. FIG. [Figure 11] FIG. 11 is a plan view of a battery unit according to a fourth modified example of the first embodiment. [Figure 12] FIG. 11 is a plan view of a flexible printed circuit board according to a second embodiment. [Figure 13]FIG. 13(a) is a partially enlarged plan view of a branching portion and its surrounding structure in a first modified example of the second embodiment, and FIG. 13(b) is a partially enlarged plan view of a branching portion and its surrounding structure in a second modified example of the second embodiment. [Figure 14] FIG. 13 is a plan view of a voltage monitoring module according to a third modified example of the second embodiment. [Figure 15] FIG. 13 is a plan view of a voltage monitoring module according to a third embodiment. [Figure 16] FIG. 13 is a bottom view of the flexible printed circuit board according to the third embodiment. [Figure 17] FIG. 13 is a bottom view of the flexible printed circuit board according to Modification 1 of the third embodiment. [Figure 18] FIG. 13 is a plan view of a flexible printed circuit board according to a second modified example of the third embodiment. [Figure 19] FIG. 13 is a perspective view of a flexible printed circuit board according to a fourth embodiment. [Figure 20] 20A and 20B are side views showing an expandable section and its surrounding structure in a fourth embodiment, in which FIG. 20A shows a state in which the battery pack is discharging, and FIG. 20B shows a state in which the battery pack is charging. [Figure 21] FIG. 13 is a plan view of a battery unit according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0011] [First embodiment] First, the first embodiment will be described with reference to FIG. 1 to FIG.

[0012] As shown in Figures 1 and 2, the voltage monitoring module 100 of this embodiment is a voltage monitoring module that monitors the voltage state of a battery pack 200 in which a number of compartments 250, each having a number of battery cells 210 stacked in a first direction, are arranged in a first direction, and the voltage monitoring module 10 includes a number of flexible printed circuit boards 10 each corresponding to one of the multiple compartments 250. Each of the multiple flexible printed circuit boards 10 includes a main body portion 11 extending in a first direction (in this embodiment, the X direction shown in Figure 1, etc.) and multiple branch portions 20 branching off from the main body portion 11 and arranged intermittently in the first direction. The branch portion 20 has a connection terminal 55 (see Figure 6 (a)) at its tip end portion which is connected to a cell terminal 220 which is a terminal of the battery cell 210, and the connection terminal 55 of the branch portion 20 of each flexible printed circuit board 10 is connected to the cell terminal 220 of the battery cell 210 in the section 250 corresponding to that flexible printed circuit board 10. The first direction here refers to the longitudinal direction of the main body 11. The section 250 here refers to a section formed of a plurality of battery cells 210 that are continuously arranged in the first direction. In the case of this embodiment, the plurality of battery cells 210 are arranged in a straight line in the first direction. Moreover, "corresponding to each of the multiple sections 250" means that each section 250 and each flexible printed circuit board 10 correspond one-to-one to each other. Each connection terminal 55 of each flexible printed circuit board 10 is connected to the cell terminal 220 of the battery cell 210 in the corresponding section 250, but is not connected to the cell terminal 220 of the battery cell 210 in the section 250 corresponding to another flexible printed circuit board 10. Moreover, each connection terminal 55 is connected to one of the cell terminals 220 in the corresponding section 250 .

[0013] The voltage monitoring module 100 is attached to the battery pack 200 so that the longitudinal direction (ie, the first direction) of the main body 11 is aligned with the stacking direction of the battery cells 210, and each connection terminal 55 is connected to a corresponding cell terminal 220. 4(a) and 4(b), when the battery pack 200 is charged, each of the multiple battery cells 210 expands in the stacking direction (first direction) in a direction (the direction of arrow A shown in FIG. 4(a)) away from a first reference position 510 (in this embodiment, the right end of the battery pack 200) based on the first reference position 510. When the battery pack 200 is discharged, each of the multiple battery cells 210 contracts in a direction (the direction opposite to the direction of arrow A shown in FIG. 4(a)) approaching the first reference position 510 based on the first reference position 510 (same as above). In addition, at least a portion of the flexible printed circuit board 10 in the longitudinal direction (first direction) is directly or indirectly fixed to the battery pack 200, and the fixed position of the portion in the first direction relative to the battery pack 200 is a reference position for movement of the connection terminal 55 (hereinafter, a second reference position 520 (see FIG. 2, etc.)). When the battery pack 200 is being charged, as the battery cells 210 expand, each cell terminal 220 moves in the first direction away from the first reference position 510. The connection terminal 55 connected to the cell terminal 220 moves in a direction away from the second reference position 520 (in the direction of arrows B and C in FIG. 2 in this embodiment) following the cell terminal 220. The movable range of the connection terminal 55 at this time is determined according to the length of the branch section 20 having the connection terminal 55. More specifically, the larger the length of the branch section 20, the wider the movable range of the connection terminal 55. Furthermore, when the battery pack 200 is discharged, as the multiple battery cells 210 contract, each cell terminal 220 moves in the first direction toward the first reference position 510. Furthermore, the connection terminal 55 connected to the cell terminal 220 moves in a direction toward the second reference position 520 following the cell terminal 220. The movable range of the connection terminal 55 at this time is determined according to the length dimension of the branch section 20 having the connection terminal 55. More specifically, the larger the length dimension of the branch section 20, the wider the movable range of the connection terminal 55.

[0014] Here, among the multiple connection terminals 55, the connection terminal 55 connected to a cell terminal 220 located farther from the second reference position 520 in the first direction requires a larger amount of movement to follow that cell terminal 220 (to absorb fluctuations in the cell terminal 220). In contrast, the voltage monitoring module 100 according to this embodiment includes a plurality of flexible printed circuit boards 10 each corresponding to one of the plurality of sections 250 of the battery pack 200. The connection terminal 55 of each of the branch portions 20 of the plurality of flexible printed circuit boards 10 is connected to the cell terminal 220 of the battery cell 210 in the section 250 corresponding to the flexible printed circuit board 10. As a result, when the battery cell 210 expands or contracts, each connection terminal 55 of each flexible printed circuit board 10 can selectively follow the cell terminal 220 of the battery cell 210 in the corresponding section 250 among all the battery cells 210 in the battery pack 200. In other words, compared to the case where the flexible printed circuit board 10 corresponds to the entire battery pack 200, the amount of movement required for each connection terminal 55 to follow the corresponding cell terminal 220 (to absorb fluctuations in the cell terminal 220) can be made smaller. Therefore, according to this embodiment, the connection terminal 55 can smoothly follow the movement of the corresponding cell terminal 220. Furthermore, since the amount of movement required for each connection terminal 55 to follow the corresponding cell terminal 220 can be made smaller, the length dimension of the branch portion 20 that determines the movable range of each connection terminal 55 can be set to be smaller. Therefore, according to this embodiment, the connection terminal 55 can be configured to closely follow the movement of the corresponding cell terminal 220, while the length dimension of the branch section 20 and thus the entire voltage monitoring module 100 can be designed to be more compact.

[0015] The battery unit 300 according to this embodiment includes the voltage monitoring module 100 according to this embodiment and a battery pack 200. Each connection terminal 55 of the flexible printed circuit board 10 is connected to a corresponding cell terminal 220 of the battery pack 200 .

[0016] According to the present embodiment, as described above, there are provided a plurality of flexible printed circuit boards 10 each corresponding to one of the plurality of sections 250 of the battery pack 200. The connection terminal 55 of each of the branch portions 20 of the plurality of flexible printed circuit boards 10 is connected to the cell terminal 220 of the battery cell 210 in the section 250 corresponding to the flexible printed circuit board 10. This allows the connection terminals 55 to smoothly follow the movement of the corresponding cell terminals 220, while also allowing the length of the branch section 20 and therefore the entire voltage monitoring module 100 to be designed more compactly.

[0017] In the following, when describing the positional relationship between the components of the voltage monitoring module 100 and the battery unit 300, one side in the first direction is referred to as the right (right side), and the other side is referred to as the left (left side). In addition, in the second direction (Y direction shown in Figs. 1 and 2, etc.) perpendicular to both the normal direction of the main body 11 and the first direction, one side is referred to as the front (forward), and the other side is referred to as the rear (rear). In addition, the direction perpendicular to both the first direction and the second direction is referred to as the up-down direction, and in the up-down direction, one side is referred to as the up (upward), and the other side is referred to as the down (downward). In addition, the direction perpendicular to the up-down direction is referred to as the horizontal (horizontal direction), and the direction along the up-down direction is referred to as the vertical (vertical direction). Moreover, the positional relationship and shape of each part of the voltage monitoring module 100 and the battery unit 300 are described based on the positional relationship and shape when the battery pack 200 is being discharged, unless otherwise specified.

[0018] For example, a connector 90 (see FIG. 5) is attached to the flexible printed circuit board 10, and the flexible printed circuit board 10 is connected to a measuring device that performs various controls via the connector 90, enabling voltage monitoring. Note that the connector 90 is not shown in FIGS. 1 and 2. The flexible printed circuit board 10 is used for monitoring voltage by connecting wiring 51 to a bus bar 70 (described in detail later) that connects a plurality of battery cells 210, for example. The connector 90 is attached to the upper surface of, for example, the end portion (the left end portion in this embodiment) of the main body portion 11 of the flexible printed circuit board 10 opposite to the side where the branch portion 20 is formed.

[0019] As shown in FIGS. 1 to 3, the shape of each of the main body portions 11 of the flexible printed circuit boards 10 is, for example, a substantially rectangular shape that is elongated in a first direction in a plan view. The multiple flexible printed circuit boards 10 are arranged, for example, parallel to one another in the second direction.

[0020] Here, in this embodiment, the main body portion 11 of one or more flexible printed circuit boards 10 has a corresponding section extension portion 12 extending in a first direction along a section 250 corresponding to the flexible printed circuit board 10, and another section extension portion 13 extending in the first direction along a section 250 corresponding to another flexible printed circuit board 10. As shown in FIGS. 2 and 3, in the flexible printed circuit board 10, of the relevant section extending portion 12 and the other section extending portion 13, a plurality of branch portions 20 are formed in the relevant section extending portion 12. In FIG. According to such a configuration, for example, by adjusting the length dimension of the other section extension portion 13, the positions of the end portions (left end portions) of the flexible printed circuit boards 10 opposite to the side where the branch portion 20 is formed can be aligned with each other in the second direction. This allows the attachment positions of the flexible printed circuit boards 10 to the battery pack 200 and the positions of the connectors 90 attached to the flexible printed circuit boards 10 to be aligned with each other in the second direction. In this embodiment, the corresponding section extension portion 12 extends in the first direction from the battery cell 210 on one end side of the corresponding section 250 to the battery cell 210 on the other end side. More specifically, in the first direction, the length dimension of the corresponding section extension portion 12 is set to be equal to or greater than the length dimension of the corresponding section 250. However, in the present invention, the length dimension of the corresponding section extension portion 12 may be smaller than the length dimension of the corresponding section 250. Moreover, the other section extension portion 13 extends in the first direction from the battery cell 210 on one end side of the section 250 corresponding to the other flexible printed circuit board 10 to the battery cell 210 on the other end side. More specifically, in the first direction, the length dimension of the other section extension portion 13 is set to be equal to or greater than the total value of the length dimensions of the sections 250 corresponding to the other flexible printed circuit boards 10. However, in the present invention, the length dimension of the other section extension portion 13 may be smaller than the total value of the length dimensions of the sections 250 corresponding to the other flexible printed circuit boards 10.

[0021] As an example, the main bodies 11 of the multiple flexible printed circuit boards 10 are separated from each other. According to such a configuration, the positions of the main bodies 11 of the multiple flexible printed circuit boards 10 relative to the battery pack 200 can be designed with a wider degree of freedom. Note that "separate from each other" here means that the main body parts 11 of the multiple flexible printed circuit boards 10 are each made of a different member, and these main body parts 11 are not directly connected to each other. Therefore, for example, the main body parts 11 may be indirectly connected to each other via another member (for example, a partition plate 260 described later).

[0022] More specifically, in this embodiment, the battery pack 200 has three sections 250 (first section 250a, second section 250b, and third section 250c, in that order from the left). The voltage monitoring module 100 has three flexible printed circuit boards 10 (first flexible printed circuit board 10a, second flexible printed circuit board 10b, and third flexible printed circuit board 10c) corresponding to each of the three sections 250. The main body portions 11 of the first flexible printed circuit board 10a to the third flexible printed circuit board 10c are separated from each other. The first flexible printed circuit board 10a corresponds to the second section 250b and has a corresponding section extension portion 12 extending in a first direction along the second section 250b and an other section extension portion 13 extending in the first direction along the first section 250a. The left end portion of the first flexible printed circuit board 10a is formed by the left end portion of the other section extension portion 13 of the first flexible printed circuit board 10a, and the right end portion of the first flexible printed circuit board 10a is formed by the right end portion of the corresponding section extension portion 12 of the first flexible printed circuit board 10a. The second flexible printed circuit board 10b corresponds to the first section 250a and has a corresponding section extension portion 12 extending in the first direction along the first section 250a, but does not have an other section extension portion 13. The left end portion of the second flexible printed circuit board 10b is formed by the left end portion of the corresponding section extension portion 12 of the first flexible printed circuit board 10a, and the right end portion of the second flexible printed circuit board 10b is formed by the right end portion of the corresponding section extension portion 12 of the second flexible printed circuit board 10b. The third flexible printed circuit board 10c corresponds to the third section 250c, and has a section extension portion 12 extending in the first direction along the third section 250c, and an other section extension portion 13 extending in the first direction along the first section 250a and the second section 250b. The left end portion of the third flexible printed circuit board 10c is formed by the left end portion of the other section extension portion 13 of the third flexible printed circuit board 10c, and the right end portion of the third flexible printed circuit board 10c is formed by the right end portion of the other section extension portion 12 of the third flexible printed circuit board 10c.

[0023] In this embodiment, the third flexible printed board 10c, the first flexible printed board 10a, and the second flexible printed board 10b are arranged side by side in this order from the rear side in the second direction. More specifically, with respect to the battery pack 200, the third flexible printed circuit board 10c and the first flexible printed circuit board 10a are each disposed on one side in the second direction (in this embodiment, rearward), and the second flexible printed circuit board 10b is disposed on the other side in the second direction (in this embodiment, frontward). Moreover, the first flexible printed circuit board 10a is disposed between the third flexible printed circuit board 10c and the battery pack 200 in the second direction. The multiple branch portions 20 of the third flexible printed circuit board 10c are formed on the front edge of the corresponding section extension portion 12 of the third flexible printed circuit board 10c, and the connection terminals 55 of these multiple branch portions 20 are connected to the cell terminals 220 of the battery cells 210 in the third section 250c. Similarly, the multiple branch portions 20 of the first flexible printed circuit board 10a are formed on the front edge of the corresponding section extension portion 12 of the first flexible printed circuit board 10a, and the connection terminals 55 of these multiple branch portions 20 are connected to the cell terminals 220 of the battery cells 210 in the second section 250b. The multiple branch portions 20 of the second flexible printed circuit board 10b are formed at the rear edge of the corresponding section extension portion 12 of the second flexible printed circuit board 10b, and the connection terminals 55 of these multiple branch portions 20 are connected to the cell terminals 220 of the battery cells 210 in the first section 250a.

[0024] Here, in the case of this embodiment, the relevant section extension portion 12 of one or more flexible printed circuit boards 10 is formed, for example, to be wider than the other section extension portions 13 of the flexible printed circuit boards 10 (having a larger dimension in the second direction). According to this configuration, even if one or more flexible printed circuit boards 10 are disposed farther away from the battery pack 200 than other flexible printed circuit boards 10 in the second direction, it is easy to dispose the branch portion 20 formed in the corresponding section extension portion 12 near the battery pack 200. Therefore, the connection terminal 55 of the flexible printed circuit board 10 can be satisfactorily connected to the corresponding cell terminal 220. More specifically, for example, as shown in Fig. 2, when the flexible printed circuit board 10 and another flexible printed circuit board 10 are disposed apart from each other in the second direction, it is preferable that the width dimension of the corresponding section extension portion 12 of the flexible printed circuit board 10 is set to a dimension larger than the separation distance between the flexible printed circuit board 10 and the other flexible printed circuit board 10. More preferably, the width dimension of the corresponding section extension portion 12 is approximately equal to the sum of the separation distance between the flexible printed circuit board 10 and the other flexible printed circuit board 10 and the width dimension of the corresponding section extension portion 12 of the other flexible printed circuit board 10. With this configuration, the position of the corresponding section extension portion 12 of the flexible printed circuit board 10 and the position of the other corresponding section extension portion 12 can be aligned with each other in the second direction. In the present embodiment, as an example, the corresponding section extension 12 of the third flexible printed circuit board 10c, which is disposed farthest from the battery pack 200 in the second direction among the multiple flexible printed circuit boards 10, is wider than the first flexible printed circuit board 10a. More specifically, the width dimension of the corresponding section extension 12 of the third flexible printed circuit board 10c is, for example, approximately twice the width dimension of the first flexible printed circuit board 10a.

[0025] As shown in FIGS. 1 and 2, the third flexible printed circuit board 10c is the largest in length dimension (dimension in the first direction), followed by the first flexible printed circuit board 10a and the second flexible printed circuit board 10b. More specifically, the left ends of the first to third flexible printed boards 10a to 10c are positioned at the same positions in the first direction. Meanwhile, the right end of the second flexible printed board 10b terminates near the right end of the first section 250a, the right end of the first flexible printed board 10a terminates near the right end of the second section 250b, and the right end of the third flexible printed board 10c terminates near the right end of the third section 250c.

[0026] As described above, in this embodiment, the section extension 12 of the third flexible printed circuit board 10c is formed to be wider (has a larger dimension in the second direction) than the other section extension 13 of the third flexible printed circuit board 10c. On the other hand, the corresponding section extension 12 of the first flexible printed circuit board 10a is set to have the same width dimension as the other section extension 13 of the first flexible printed circuit board 10a. More specifically, the entire main body 11 of the first flexible printed circuit board 10a has a constant width dimension regardless of the position in the longitudinal direction (first direction). Similarly, the entire body portion 11 of the second flexible printed circuit board 10b including the section extension portion 12 has a constant width dimension regardless of the position in the longitudinal direction (first direction). The other section extension portion 13 of the third flexible printed board 10c, the main body portion 11 of the first flexible printed board 10a, and the main body portion 11 of the second flexible printed board 10b are set to have, for example, the same width dimension as each other.

[0027] Also, as shown in FIG. 2, in the first direction, the second reference position 520 of the flexible printed circuit board 10 corresponding to the section 250 located farther from the first reference position 510 is set to be located farther from the first reference position 510. According to such a configuration, in each flexible printed circuit board 10, the amount of movement required for the connection terminals 55 to follow the corresponding cell terminals 220 (to absorb fluctuations of the cell terminals 220) can be made small. More specifically, in this embodiment, both ends of the main body 11 of the first flexible printed circuit board 10a are fixed to the battery pack 200 (for example, via a partition plate 260 described later). Among these, a fixed position of the end of the main body 11 of the first flexible printed circuit board 10a on the first reference position 510 side (the right end in this embodiment) relative to the battery pack 200 in the first direction is the second reference position 520 (hereinafter, the second reference position 520a) of the first flexible printed circuit board 10a. The second reference position 520a of the first flexible printed circuit board 10a is located near the battery cell 210 located closest to the first reference position 510 in the second section 250b. Similarly, both ends of the main body 11 of the third flexible printed circuit board 10c are fixed to the battery pack 200 (same as above). Of these, the fixed position of the end of the main body 11 of the third flexible printed circuit board 10c on the first reference position 510 side (the right end in this embodiment) relative to the battery pack 200 in the first direction is the second reference position 520 (hereinafter, the second reference position 520c) of the third flexible printed circuit board 10c. The second reference position 520c of the third flexible printed circuit board 10c is located near the battery cell 210 located closest to the first reference position 510 in the third section 250c. On the other hand, an end portion (left end portion in this embodiment) of the main body portion 11 of the second flexible printed circuit board 10b opposite to the first reference position 510 side is fixed (same as above) to the battery pack 200, and an end portion (right end portion in this embodiment) on the first reference position 510 side is not fixed to the battery pack 200. A fixed position of the end portion (same as above) of the second flexible printed circuit board 10b opposite to the first reference position 510 side relative to the battery pack 200 in the first direction is a second reference position 520 (hereinafter, second reference position 520b) of the second flexible printed circuit board 10b. The second reference position 520b of the second flexible printed circuit board 10b is located near the battery cell 210 located farthest from the first reference position 510 in the first section 250a.

[0028] Furthermore, in this embodiment, in each flexible printed circuit board 10, the distance in the first direction between the second reference position 520 and the cell terminal 220 located farthest from the second reference position 520 in the corresponding section 250 is set to be approximately equal to each other. According to this configuration, the maximum amount of movement required for the connection terminal 55 to follow the corresponding cell terminal 220 (to absorb the fluctuation of the cell terminal 220) can be made substantially equal in each flexible printed circuit board 10. Therefore, the movement of the cell terminal 220 caused by the expansion and contraction of the battery cell 210 can be absorbed by distributing it substantially evenly among the flexible printed circuit boards 10. Furthermore, it is possible to reduce the maximum amount of movement required for the connection terminals 55 to follow the movement of the corresponding cell terminals 220, compared to when the flexible printed circuit board 10 corresponds to the entire battery pack 200. Therefore, while enabling the connection terminals 55 in each flexible printed circuit board 10 to favorably follow the movement of the corresponding cell terminals 220, it is possible to design the length dimension of the branching section 20, and therefore the entire voltage monitoring module 100, to be more compact.

[0029] In the present invention, it is not necessarily required that a flexible printed circuit board 10 is arranged on each side of the battery pack 200 in the second direction (in this embodiment, the front and rear). For example, multiple flexible printed circuit boards 10 may be selectively arranged on one side of the battery pack 200 in the second direction (in this embodiment, the front or rear). In the present invention, the flexible printed circuit board 10 arranged on one side of the battery pack 200 in the second direction and the flexible printed circuit board 10 arranged on the other side in the second direction may be arranged interchangeably. In this case, the shape and the orientation of the plate surface of the flexible printed circuit board 10 are appropriately set so that the side edge on the side where the branch portion 20 is formed of the flexible printed circuit board 10 is arranged on the battery pack 200 side.

[0030] Here, among the multiple flexible printed circuit boards 10, the other section extension portion 13 of the main body portion 11 of one or more flexible printed circuit boards 10 has, for example, an expansion / contraction portion 80 (see FIG. 5) that is expandable and contractable in a first direction. Note that in FIG. 1, for convenience, the expansion / contraction portion 80 is omitted from illustration, and the other section extension portion 13 is illustrated as a flat shape in its entirety. With this configuration, the other section extension portion 13 can follow the expansion and contraction of the battery cell 210 in the section 250 corresponding to the other flexible printed circuit board 10 (absorb the expansion and contraction of the battery cell 210) by the expansion and contraction of the expansion and contraction portion 80.

[0031] As shown in Figs. 5, 7(a) and 7(b), in this embodiment, in the stretchable section 80, the main body section 11 is folded back so that parts of the main body section 11 overlap each other. According to such a configuration, the maximum extension range of the stretchable section 80 and the minimum contraction range of the stretchable section 80 can both be satisfactorily secured. Here, "parts of main body 11 overlap" means that they overlap in a direction parallel to the normal direction of the flat extending portion of main body 11.

[0032] More specifically, for example, in the stretchable portion 80, the main body portion 11 is folded back in a meandering manner in the first direction by one and a half round trips or more. With this configuration, the maximum extension range of the stretchable portion 80 can be satisfactorily ensured.

[0033] More specifically, in this embodiment, the other section extending portion 13 of the first flexible printed circuit board 10a and the other section extending portion 13 of the third flexible printed circuit board 10c each have an expandable portion 80. As shown in FIG. 5 and FIG. 7(a), in the present embodiment, in each of the stretching sections 80 of the first flexible printed circuit board 10a and the third flexible printed circuit board 10c, the other section extension section 13 is folded back in a meandering manner in the first direction for approximately one and a half round trips, and a portion of the other section extension section 13 is curved in a shape of a substantially S-shaped letter laid down on its side in a front view. More specifically, the portion of the other section extension section 13 is folded back while curving from the second reference position 520 side (hereinafter, simply the right side) toward the opposite side of the second reference position 520 (hereinafter, simply the left side) in the first direction, and then further folded back while curving from the left side to the right side in the first direction. In the stretching section 80, the portion folded back from the left side to the right side (hereinafter, the first portion 81) is stacked on the portion folded back from the right side to the left side (hereinafter, the second portion 82). A plane of a portion of the first portion 81 and a plane of a portion of the second portion 82 are opposed to each other in the up-down direction. As shown in FIG. 2, the extensible portion 80 of the third flexible printed circuit board 10c extends along substantially the entirety of each of the first section 250a and the second section 250b in the first direction. Moreover, the extensible portion 80 of the first flexible printed circuit board 10a extends along substantially the entire first section 250a in the first direction. 5, 7(a) and 7(b), the stretchable portion 80 of the first flexible printed circuit board 10a is selectively illustrated, and the stretchable portion 80 of the third flexible printed circuit board 10c is omitted. In the present invention, the shape of the stretchable portion 80 is not limited to the above-mentioned example, and may be folded back in a meandering manner about two and a half to three and a half times in the first direction, for example. Furthermore, in the present embodiment, the main body 11 of the expandable part 80 is in an extended state before being attached to the battery pack 200, and is configured to be folded back (contracted) by being fixed to the battery pack 200. However, in the present invention, the main body 11 of the expandable part 80 may be in a folded back (contracted) state even before being attached to the battery pack 200 (for example, by being held by a case 65 described later).

[0034] In this embodiment, when the battery pack 200 is charged, the expanding and contracting portion 80 expands in a direction away from the second reference position 520 in accordance with the expansion of the battery cells 210 in the section 250 corresponding to the other flexible printed circuit boards 10. More specifically, as the battery cells 210 expand, the folding start point 80a of the expanding and contracting portion 80 also moves in the same direction. At this time, a part of the expanding and contracting portion 80 is deformed from a folded-back shape to a shape extending substantially flat (see FIG. 7(b)). Then, as the connection terminal 55 moves, the dimension of the part of the expanding and contracting portion 80 that extends substantially flat gradually increases, and the dimension of the folded-back part gradually decreases. In this way, the expanding and contracting portion 80 can expand in a direction away from the second reference position 520. Furthermore, when the battery pack 200 is discharged, the expandable portion 80 contracts in a direction approaching the second reference position 520 as the battery cells 210 in the sections 250 corresponding to the other flexible printed circuit boards 10 contract. More specifically, as the battery cells 210 contract, the folding start point 80a of the expandable portion 80 also moves in the same direction. At this time, a part of the expandable portion 80 is deformed from a shape extending substantially flat to a folded-back shape (see FIG. 7(a)). Then, as the connection terminal 55 moves, the dimension of the part extending substantially flat in the expandable portion 80 gradually decreases, and the dimension of the folded-back part gradually increases. In this way, the expandable portion 80 can contract in a direction approaching the second reference position 520. In the present invention, the "starting point 80a of the fold" means the position where the other-section extending portion 13 starts to rise from a state in which it extends flat.

[0035] As shown in FIGS. 2 and 3, the branch portion 20 includes, for example, a first direction extending portion 22 that extends in a first direction. More specifically, each of the multiple branched portions 20 has, for example, a protruding portion 26 protruding from the main body portion 11 in a second direction (Y direction) perpendicular to both the normal direction of the main body portion 11 and the first direction (X direction), a first direction extending portion 22 extending in the first direction from the tip of the protruding portion 26, and a tip protruding portion 28 protruding in the second direction from the tip of the first direction extending portion 22 (the end portion opposite to the protruding portion 26 side). As shown in FIG. 6(a), the tip protruding portion 28 has a connection terminal 55. Note that in figures other than FIG. 6(a), illustration of the connection terminal 55 is omitted as appropriate. Each of the first direction extending portion 22, the protruding portion 26, and the tip protruding portion 28 extends linearly in a plan view.

[0036] In this embodiment, when the battery pack 200 is being charged, when each connection terminal 55 moves in the first direction, following the corresponding cell terminal 220, in a direction away from the first reference position 510, the tip protrusion 28 of the branch portion 20 is also pulled by the cell terminal 220 and moves in a direction away from the second reference position 520. When the movement amount of the cell terminal 220 (the movement distance of the cell terminal 220 in the first direction) is smaller than the length dimension of the first direction extending portion 22, a portion of the first direction extending portion 22 bends in an upwardly convex arc shape. This allows the connection terminal 55 to follow the corresponding cell terminal 220. On the other hand, when the movement amount (same as above) of the cell terminal 220 is larger than the length dimension of the first direction extending portion 22, a part of the first direction extending portion 22 is deformed into a shape that is curved and folded back from the second reference position 520 side toward the opposite side of the second reference position 520 in the first direction. More specifically, the flat surfaces of parts of the first direction extending portion 22 face each other in the up-down direction. Then, as the tip protrusion 28 moves in a direction away from the second reference position 520, the starting point 80a of the folding back of the first direction extending portion 22 also moves in the same direction. At this time, the dimension of the part located on the lower side of the first direction extending portion 22 gradually decreases, and the dimension of the part located on the upper side gradually increases. This allows the connection terminal 55 to follow the corresponding cell terminal 220.

[0037] In addition, when the battery pack 200 is discharged, when each connection terminal 55 moves in the first direction, following the corresponding cell terminal 220, in a direction approaching the first reference position 510, the tip protrusion 28 of the branch portion 20 is also pulled by the cell terminal 220 and moves in a direction approaching the second reference position 520. At this time, if a portion of the first direction extending portion 22 is bent into an upwardly convex arc shape during charging of the battery pack 200, the bent portion deforms (restores) to a shape extending substantially flat. This allows the connection terminal 55 to follow the corresponding cell terminal 220. On the other hand, when a part of the first direction extending part 22 is deformed into a shape that is curved and folded back from the second reference position 520 side toward the opposite side of the second reference position 520 in the first direction during charging of the battery pack 200, as the tip protruding part 28 moves in a direction approaching the second reference position 520, the starting point 80a of the folding back of the first direction extending part 22 also moves in the same direction. At this time, in the first direction extending part 22, the dimension of the part located on the lower side gradually increases, and the dimension of the part located on the upper side gradually decreases. Therefore, the part of the first direction extending part 22 is deformed (returned) from the folded back shape to a shape that extends substantially flat. This allows the connection terminal 55 to follow the corresponding cell terminal 220.

[0038] Also, the branching portion 20 is bent around an axis AX (see FIG. 6(a)) that intersects with both the normal direction of the main body 11 and the first direction, and has a first portion 35 extending in the first direction and a second portion 37 having a connection terminal 55 and standing from the first portion 35. In FIG. 6(a), the axis AX is illustrated by a two-dot chain line. In this embodiment, the axis AX is perpendicular to both the normal direction (vertical direction) of the main body 11 and the first direction, and the axial direction of the axis AX is the second direction. However, in the present invention, the axis AX only needs to intersect with at least both the normal direction of the main body 11 and the first direction, and does not necessarily have to be perpendicular to both the normal direction of the main body 11 and the first direction. As a result, a part (second portion 37) of the branch portion 20 stands up in advance, and this standing portion has the connection terminal 55. Therefore, when the battery pack 200 is charged, the first direction extending portion 22 can be smoothly deformed in the first direction into a shape folded back from the second reference position 520 side toward the opposite side of the second reference position 520. That is, the connection terminal 55 can smoothly move in a direction away from the second reference position 520 in accordance with the movement of the cell terminal 220. More specifically, in this embodiment, the tip portion of the first direction extending portion 22 and the tip protrusion 28 constitute the second portion 37, and the portion of the tip portion of the first direction extending portion 22 excluding the second portion 37 constitutes the first portion 35.

[0039] In this embodiment, the first direction extending portions 22 of the first flexible printed circuit board 10a to the third flexible printed circuit board 10c are set to have the same length dimension as each other. That is, the movable ranges of the connection terminals 55 of the first flexible printed circuit board 10a to the third flexible printed circuit board 10c are set to be the same as each other. Even in such a case, as described above, the voltage monitoring module 100 according to this embodiment can reduce the amount of movement required for each connection terminal 55 to follow the corresponding cell terminal 220 (to absorb fluctuations in the corresponding cell terminal 220). Therefore, while allowing the connection terminals 55 to smoothly follow the movement of the corresponding cell terminal 220, the length of the branching section 20 and therefore the entire voltage monitoring module 100 can be designed to be more compact. More specifically, the branching portions 20 of the first flexible printed circuit board 10a and the third flexible printed circuit board 10c are set to have the same shape and dimensions as each other. Also, the branching portion 20 of the second flexible printed circuit board 10b is formed in a shape symmetrical with respect to the front and rear and is disposed symmetrical with respect to the front and rear of the branching portions 20 of the third flexible printed circuit board 10c and the first flexible printed circuit board 10a. However, in the present invention, the branch portions 20 of the multiple flexible printed circuit boards 10 may be set to different shapes and dimensions.

[0040] The multiple wirings 51 each extend from within the main body 11 to the tip protruding portion 28 of each branch portion 20. For example, one wiring 51 is disposed for each branch portion 20. One connection terminal 55 is formed on each tip protruding portion 28, and the tip of each wiring 51 is connected to the corresponding connection terminal 55. The connection terminal 55 is exposed on the surface of the tip protruding portion 28, for example.

[0041] 1, the voltage monitoring module 100 includes, for example, a flexible printed circuit board 10 and a plurality of bus bars 70, and a plurality of battery cells 210 are connected in series by these bus bars 70. However, in the present invention, the bus bars 70 may also connect, for example, some of the plurality of battery cells 210 in parallel. The bus bar 70 is disposed so as to overlap the cell terminal 220 and is connected (for example, by laser welding) to the cell terminal 220. Note that the bus bar 70 is not shown in FIG. The busbar 70 is formed by bending a flat metal member multiple times. The shape of the busbar 70 is not particularly limited, but as an example, the busbar 70 is formed in a generally U-shape when viewed from the front. More specifically, the bus bar 70 includes a pair of left and right outer leg portions 72 and a main portion 74 disposed across the pair of left and right outer leg portions 72 . The pair of left and right outer legs 72 stand vertically, and each plate surface faces the first direction. As shown in Fig. 1 and Fig. 6(b), each outer leg 72 is disposed on top of the cell terminal 220 and connected (for example, by laser welding) to the cell terminal 220. More specifically, of two battery cells 210 disposed adjacent to each other in the first direction, the left outer leg 72 is connected to the cell terminal 220 of the left battery cell 210, and the right outer leg 72 is connected to the cell terminal 220 of the right battery cell 210. Note that in Fig. 6(b), one of the pair of left and right outer legs 72 is illustrated by a two-dot chain line. The main portion 74 is formed, for example, in a generally rectangular flat plate shape that is elongated in the first direction in a plan view, and the plate surface is disposed horizontally. In the present invention, the shape of busbar 70 is not limited to the example shown in FIG. 1, and may be, for example, substantially M-shaped when viewed from the front.

[0042] 2, in this embodiment, the battery unit 300 includes, for example, a housing 310 that houses the battery pack 200, and a cushioning material 320 that biases the multiple battery cells 210 toward the first reference position 510. In addition, in FIG. 2, the housing 310 and the cushioning material 320 are illustrated by two-dot chain lines. As shown in FIG. 2, the entire battery pack 200 is housed in a housing 310. In the present invention, the battery unit 300 may include a thermistor (not shown) for detecting the temperature of the battery pack 200, and wiring (not shown) for connecting the thermistor to a measuring device that performs various controls. The cushioning material 320 biases the multiple battery cells 210 toward the first reference position 510. The cushioning material 320 is capable of expanding and contracting in a first direction in accordance with the expansion and contraction of the battery cells 210. More specifically, when the battery pack 200 is charged, the cushioning material 320 is pressed by the battery cells 210 and compressed in the first direction against the elastic restoring force. When the battery pack 200 is discharged, the cushioning material 320 elastically restores and expands in the first direction. Therefore, even if the battery cells 210 repeatedly expand and contract, the pair of left and right cushioning materials 320 can prevent the left end of the battery pack 200 (the first reference position 510) from being displaced relative to the housing 310. The buffer material 320 is not particularly limited, but in this embodiment, a cushion member can be used as an example. However, in the present invention, the cushioning material 320 may be a spring member or the like that biases the battery cell 210 toward the first reference position 510 side.

[0043] Each of the multiple battery cells 210 is a secondary battery. 1 and 2, each of the plurality of battery cells 210 is formed in a rectangular flat plate shape when viewed from the side. Each of the plurality of battery cells 210 is set to have the same shape and the same dimensions as one another. Each of the plurality of battery cells 210 has, for example, a pair of front and rear cell terminals 220. Each of the pair of front and rear cell terminals 220 stands upward from, for example, an upper end surface of the corresponding battery cell 210. The shape of the cell terminal 220 is not particularly limited, but as an example, it is formed in a generally rectangular flat plate shape when viewed from the side, and the plate surface faces in the first direction. To each connection terminal 55, one cell terminal 220 is connected.

[0044] As shown in Fig. 6(a), in this embodiment, the connection terminal 55 is connected to the cell terminal 220 in a position perpendicular to the main body 11. In Fig. 6(a) and Fig. 6(b), the cell terminal 220 is illustrated by a two-dot chain line. This allows the connection terminal 55 to move smoothly in the first direction away from the first reference position 510 in response to the movement of the cell terminal 220.

[0045] In this embodiment, as shown in FIG. 6(b), the connection terminal 55 is connected to the cell terminal 220 via a welding plate 40, for example. The shape of the welded plate 40 is not particularly limited, but as an example, it is formed in a substantially rectangular flat plate shape, with the plate surface facing the first direction. The welding plate 40 is disposed so as to overlap one surface of the cell terminal 220, and is joined to the one surface by welding. The side end portion of the welding plate 40 on the branch portion 20 side protrudes from the cell terminal 220 toward the branch portion 20 side. The tip protrusion 28 of the branch portion 20, and thus the connection terminal 55, are connected to the portion of the welding plate 40 protruding from the cell terminal 220. More specifically, the tip portion of the tip protrusion 28 is disposed, for example, so as to overlap the surface of the welding plate 40 on the cell terminal 220 side, and is soldered to the surface on the cell terminal 220 side. In this manner, the connection terminal 55 is electrically connected to the cell terminal 220 in a position perpendicular to the main body 11 . However, in the present invention, the method of connecting the connection terminal 55 to the cell terminal 220 is not limited to this example, and the connection terminal 55 may be directly connected to the cell terminal 220, for example, without going through the welding plate 40. Furthermore, outer leg portion 72 of bus bar 70 is disposed so as to overlap the surface of cell terminal 220 opposite to welded plate 40 and is joined to the opposite surface. In the present invention, the bus bar 70 does not necessarily have to be connected to each of all the cell terminals 220. In the case of this embodiment, among the multiple cell terminals 220, the cell terminal 220 located on the leftmost side and the cell terminal 220 located on the rightmost side are not connected to the bus bar 70.

[0046] The battery unit 300 includes, for example, a plurality of partition plates 260, and the plurality of partition plates 260 divide the battery pack 200 into a plurality of sections 250. The plurality of partition plates 260 are arranged side by side in a first direction (stacking direction of the battery cells 210) with the plurality of battery cells 210 sandwiched therebetween. In the present embodiment, the battery pack 200 includes four partition plates 260 (from the left side, a first partition plate 260a, a second partition plate 260b, a third partition plate 260c, and a fourth partition plate 260d), and the four partition plates 260 divide the plurality of battery cells 210 into three sections 250 (a first partition plate 250a, a second partition plate 250b, and a third partition plate 250c). Each of the sections 250 includes, for example, the same number (for example, eight) of battery cells 210. However, in the present invention, the number of battery cells 210 included in each of the sections 250 may be different from each other. The plate surface of each partition plate 260 is disposed along the plate surface of the adjacent battery cell 210. In each section 250, the plate surfaces of the adjacent battery cells 210 are in surface contact with each other. In this embodiment, the fourth partition plate 260d, which is disposed closest to the first reference position 510 among the four partition plates 260, does not displace relative to the battery pack 200 when the battery cell 210 expands and contracts. On the other hand, the other partition plates 260 (the first partition plate 260a to the third partition plate 260c) move in a direction away from the first reference position 510 as the battery cell 210 expands, and move in a direction approaching the first reference position 510 as the battery cell 210 contracts. As shown in FIG. 2, the width dimension of the multiple partition plates 260 is larger than the width dimension of each battery cell 210, and in a plan view, the multiple partition plates 260 protrude beyond each battery cell 210 on both sides in the second direction.

[0047] In the case of this embodiment, as an example, the voltage monitoring module 100 is installed between a plurality of partition plates 260 and disposed above the battery pack 200. More specifically, the left end of the main body 11 of each of the first to third flexible printed boards 10a to 10c is fixed to the rear end of the upper end surface of the first partition plate 260a. Also, the right end of the main body 11 of the first flexible printed circuit board 10a is fixed to the rear end of the upper end surface of the third partition plate 260c. That is, the first flexible printed circuit board 10a extends in the first direction from the first partition plate 260a to the third partition plate 260c, straddling the second partition plate 260b (and thus the first section 250a and the second section 250b). The right end of the main body 11 of the second flexible printed circuit board 10b terminates before (on the left side of) the second partition plate 260b and is not fixed to the second partition plate 260b. A right end of the main body 11 of the third flexible printed circuit board 10c is fixed to a rear end of the upper end surface of the fourth partition plate 260d. That is, the third flexible printed circuit board 10c extends in the first direction from the first partition plate 260a to the fourth partition plate 260d, straddling the second partition plate 260b and the third partition plate 260c (and thus the first section 250a to the third section 250c). In this way, the plate-like member 60 and therefore the voltage monitoring module 100 are mounted between the multiple partition plates 260 and disposed above the battery pack 200. In this state, as described above, the voltage monitoring module 100 is attached such that the longitudinal direction (first direction) of the main body 11 is aligned with the stacking direction of the battery cells 210.

[0048] In the present invention, the main body 11 of the flexible printed circuit board 10 may be fixed directly to the partition plate 260, or may be fixed indirectly via a plate-like member 60 to be described later. Furthermore, in the present invention, the battery pack 200 does not necessarily have to include the multiple partition plates 260 as in a fifth embodiment described later.

[0049] An example of the operation of the battery unit 300 during discharging and charging will be described in more detail below. As described above, when the battery pack 200 is charged, each of the battery cells 210 expands in a direction away from the first reference position 510, with the first reference position 510 as a reference. With the expansion of the battery cells 210, each cell terminal 220 moves in a direction away from the first reference position 510 in the first direction. Also, the connection terminal 55 connected to the cell terminal 220 moves in a direction away from the corresponding second reference position 520 following the cell terminal 220. More specifically, the connection terminal 55 of each of the first flexible printed circuit board 10a and the third flexible printed circuit board 10c moves in a direction away from the second reference positions 520a, 520c (the direction of the arrow B shown in FIG. 2). The connection terminal 55 of the second flexible printed circuit board 10b moves in a direction away from the second reference position 520b (the direction of the arrow C shown in FIG. 2). Furthermore, when the battery pack 200 is discharged, each of the multiple battery cells 210 contracts to the right with respect to the first reference position 510. As the multiple battery cells 210 contract, each cell terminal 220 moves in the first direction toward the first reference position 510. Furthermore, the connection terminal 55 connected to the cell terminal 220 moves in a direction toward the corresponding second reference position 520 following the cell terminal 220. More specifically, each of the connection terminals 55 of the first flexible printed circuit board 10a and the third flexible printed circuit board 10c moves in a direction toward the second reference positions 520a, 520c. The connection terminal 55 of the second flexible printed circuit board 10b moves in a direction toward the second reference position 520b.

[0050] Here, as described above, among the multiple connection terminals 55, the connection terminal 55 connected to a cell terminal 220 located farther from the second reference position 520 in the first direction requires a larger amount of movement to follow that cell terminal 220 (to absorb fluctuations in the cell terminal 220). In this embodiment, the voltage monitoring module 100 includes a plurality of flexible printed circuit boards 10 each corresponding to one of the plurality of sections 250 of the battery pack 200. The connection terminal 55 of each of the branch portions 20 of the plurality of flexible printed circuit boards 10 is connected to the cell terminal 220 of the battery cell 210 in the section 250 corresponding to the flexible printed circuit board 10. Therefore, it is possible to reduce the amount of movement required for each connection terminal 55 to follow the corresponding cell terminal 220 (to absorb fluctuations in the corresponding cell terminal 220) compared to when the flexible printed circuit board 10 corresponds to the entire battery pack 200. Therefore, while enabling the connection terminals 55 to properly follow the movement of the corresponding cell terminal 220, it is possible to design the length dimension of the branching section 20 and therefore the entire voltage monitoring module 100 to be more compact. As described above, in this embodiment, the other section extending portion 13 of one or more flexible printed circuit boards 10 (the first flexible printed circuit board 10a and the third flexible printed circuit board 10c) has the stretchable portion 80. Therefore, the other section extension section 13 can smoothly follow the expansion and contraction of the battery cells 210 in the section 250 corresponding to the other flexible printed circuit board 10 (absorb the fluctuation of the battery cells 210) by the expansion and contraction of the expansion and contraction section 80. Therefore, the amount of movement required for each connection terminal 55 to follow the corresponding cell terminal 220 (absorb the fluctuation of the corresponding cell terminal 220) can be further reduced.

[0051] <Modification 1 of the First Embodiment> Next, a first modified example of the first embodiment will be described with reference to Fig. 8(a) and Fig. 8(b). Note that in Fig. 8(a) and Fig. 8(b), the stretchable portion 80 of the first flexible printed circuit board 10a is selectively illustrated, and the stretchable portion 80 of the third flexible printed circuit board 10c is omitted. The voltage monitoring module 100 of this modified example differs from the voltage monitoring module 100 of the first embodiment described above in the points described below, but in other respects is configured in the same way as the voltage monitoring module 100 of the first embodiment described above.

[0052] As shown in FIG. 8(a) and FIG. 8(b), in this modified example, the main body portion 11 is folded back and forth once in the first direction in the stretchable portion 80. Even with this configuration, one or more flexible printed circuit boards 10 can effectively absorb the expansion and contraction of the battery cells 210 in the sections 250 corresponding to other flexible printed circuit boards 10 by expanding and contracting the expanding and contracting sections 80. Therefore, the amount of movement required for each connection terminal 55 to follow the corresponding cell terminal 220 (to absorb the fluctuation of the corresponding cell terminal 220) can be further reduced. More specifically, a portion of the other section extending portion 13 is curved and folded back in the first direction from the second reference position 520 side toward the opposite side to the second reference position 520 side. Planes of portions of the other section extending portion 13 face each other in the up-down direction. When the battery pack 200 is being charged, as the battery cells 210 expand, the folding start point 80a of the expansion / contraction portion 80 moves in a direction away from the second reference position 520 (the direction of the arrow B in FIG. 8(a)). At this time, in the other section extension portion 13, the dimension of the portion located on the lower side gradually decreases, and the dimension of the portion located on the upper side gradually increases. This allows the expansion / contraction portion 80 to extend in a direction away from the second reference position 520. 8B, as the battery cells 210 contract, the folding start point 80a of the extension portion 80 moves toward the second reference position 520. At this time, the dimension of the lower portion of the other section extension portion 13 gradually increases, and the dimension of the upper portion gradually decreases. This allows the extension portion 80 to contract toward the second reference position 520.

[0053] <Modification 2 of the First Embodiment> Next, a second modified example of the first embodiment will be described with reference to Fig. 9(a) and Fig. 9(b). Note that in Fig. 9(a) and Fig. 9(b), the stretchable portion 80 of the first flexible printed circuit board 10a is selectively illustrated, and the stretchable portion 80 of the third flexible printed circuit board 10c is omitted. The voltage monitoring module 100 of this modified example differs from the voltage monitoring module 100 of the first embodiment described above in the points described below, but in other respects is configured in the same way as the voltage monitoring module 100 of the first embodiment described above.

[0054] As shown in FIGS. 9(a) and 9(b), in this modified example, in the expandable portion 80, the main body portion 11 is curved in the normal direction to the other portion of the expandable portion 80. Here, the "normal direction of the other part of the stretchable portion 80" means the normal direction of the part of the stretchable portion 80 that is not folded back and extends substantially flat. Even with this configuration, one or more flexible printed circuit boards 10 can effectively absorb the expansion and contraction of the battery cells 210 in the sections 250 corresponding to other flexible printed circuit boards 10 by expanding and contracting the expanding and contracting sections 80. Therefore, the amount of movement required for each connection terminal 55 to follow the corresponding cell terminal 220 (to absorb the fluctuation of the corresponding cell terminal 220) can be further reduced. More specifically, a portion of the other section extension portion 13 is curved in a generally U-shape that is convex downward, and the curved portion constitutes the stretchable portion 80. The stretchable portion 80 has a shape that moves back and forth up and down so that it descends, then ascends, and returns to its original position. When the battery pack 200 is being charged, the expansion / contraction portion 80 is deformed from a U-shaped curved shape to a flatter shape as the battery cells 210 expand. This allows the expansion / contraction portion 80 to extend in a direction away from the second reference position 520 (the direction of the arrow B shown in FIG. 9(a)). 9(a), the expandable portion 80 is deformed (restored) from a substantially flat extending shape to a U-shaped curved shape in accordance with the contraction of the battery cell 210. This allows the expandable portion 80 to contract in a direction approaching the second reference position 520.

[0055] <Modifications 3 and 4 of the First Embodiment> Next, modified examples 3 and 4 of the first embodiment will be described with reference to Figures 10 and 11. Note that in Figures 10 and 11, the stretchable portion 80 is omitted from illustration. The voltage monitoring module 100 of this modified example differs from the voltage monitoring module 100 of the first embodiment described above in the points described below, but in other respects is configured in the same way as the voltage monitoring module 100 of the first embodiment described above.

[0056] In the present invention, the number of compartments 250 in the battery pack 200 and the number of flexible printed circuit boards 10 in the voltage monitoring module 100 are not particularly limited, and can be set appropriately depending on the purpose and dimensions of the voltage monitoring module 100 and the battery unit 300. 10 and 11, the battery pack 200 has four sections 250 (from the left, a first section 250a, a second section 250b, a third section 250c, and a fourth section 250d), and the voltage monitoring module 100 has four flexible printed circuit boards 10 (a first flexible printed circuit board 10a, a second flexible printed circuit board 10b, a third flexible printed circuit board 10c, and a fourth flexible printed circuit board 10d) corresponding to each of the four sections 250. The first flexible printed circuit board 10a corresponds to the second section 250b, the second flexible printed circuit board 10b corresponds to the first section 250a, the third flexible printed circuit board 10c corresponds to the third section 250c, and the fourth flexible printed circuit board 10d corresponds to the fourth section 250d. In addition, in the first direction, the second reference position 520b of the second flexible printed circuit board 10b, the second reference position 520a of the first flexible printed circuit board 10a, the second reference position 520c of the third flexible printed circuit board 10c, and the second reference position 520d of the fourth flexible printed circuit board 10d are arranged in this order from the left side. According to such a configuration, for example, even in the case of a battery pack 200 having a larger length dimension compared to the battery pack 200 in the first embodiment, the connection terminal 55 can be configured to smoothly follow the movement of the corresponding cell terminal 220, while the length dimension of the branch section 20 and therefore the entire voltage monitoring module 100 can be designed to be more compact.

[0057] In addition, in the present invention, as described above, the flexible printed circuit board 10 arranged on one side of the battery pack 200 in the second direction and the flexible printed circuit board 10 arranged on the other side in the second direction may be arranged in an interchangeable manner. More specifically, as shown in FIG. 10, for example, with the battery pack 200 as a reference, the first flexible printed circuit board 10a and the third flexible printed circuit board 10c may each be arranged on one side (e.g., rear) in the second direction, and the second flexible printed circuit board 10b and the fourth flexible printed circuit board 10d may each be arranged on the other side (e.g., front) in the second direction. Also, as shown in FIG. 11, for example, with the battery pack 200 as a reference, the fourth flexible printed circuit board 10d and the third flexible printed circuit board 10c may each be arranged on one side in the second direction (e.g., rearward), and the second flexible printed circuit board 10b and the first flexible printed circuit board 10a may each be arranged on the other side in the second direction (e.g., forward).

[0058] Second Embodiment Next, a second embodiment will be described with reference to FIG. The voltage monitoring module 100 of this embodiment differs from the voltage monitoring module 100 of the first embodiment described above in the points described below, but in other respects is configured in the same way as the voltage monitoring module 100 of the first embodiment described above.

[0059] In this embodiment, as shown in FIG. 12, among the multiple branch portions 20 possessed by one or more flexible printed circuit boards 10, the branch portion 20 located farther away from the reference position (second reference position 520) in the first direction has a larger length dimension of the first direction extending portion 22. This makes it possible to ensure a sufficient range of movement in the direction toward the second reference position 520 and in the direction away from the second reference position 520 for the connection terminal 55 connected to the cell terminal 220 located farther from the first reference position 510 in the first direction among the multiple cell terminals 220. Therefore, even if the amount of movement of the cell terminal 220 due to the contraction or expansion of the battery cell 210 in the corresponding section 250 is large, the connection terminal 55 can smoothly follow the movement of the cell terminal 220.

[0060] In the present invention, it is sufficient that at least two of the multiple branch portions 20 included in one or more flexible printed circuit boards 10 have a relationship in which the branch portion 20 located farther from the second reference position 520 in the first direction has a longer length dimension of the branch portion 20 from the base end of the branch portion 20 to the connection terminal 55. Preferably, as described later, the branch portion 20 located farther from the second reference position 520 in the first direction has a longer length dimension of the branch portion 20 from the base end of the branch portion 20 to the connection terminal 55.

[0061] Moreover, the multiple branch portions 20 of one or more flexible printed circuit boards 10 include an offset branch portion 24 that is offset from the other branch portions 20 in a second direction (Y direction) that is perpendicular to both the normal direction of the main body portion 11 and the first direction. When viewed in the second direction, the offset branch portion 24 and the other branch portions 20 partially overlap each other. With this configuration, even if the movable range of the connection terminal 55 of the offset branch portion 24 overlaps with the movable range of the connection terminal 55 of the other branch portion 20 in the first direction, it is possible to prevent the connection terminal 55 of the offset branch portion 24 and the connection terminal 55 of the other branch portion 20 from interfering with each other when moving in accordance with the cell terminal 220.

[0062] Moreover, among the multiple branch portions 20 of one or more flexible printed circuit boards 10, a portion of some of the branch portions 20 (in this embodiment, the offset branch portion 24) is contained within a rectangle 410 that circumscribes the main body portion 11 in a plan view. In addition, in Fig. 12, the rectangle 410 is indicated by a two-dot chain line. This more reliably prevents the connection terminal 55 of the offset branch portion 24 and the connection terminal 55 of the other branch portion 20 from interfering with each other. More specifically, in the present embodiment, a slit 11a recessed forward is formed in the rear edge of the main body 11. The protrusions 26 and the first direction extending portions 22 of some of the branches 20 (offset branches 24) are disposed inside the slits 11a in plan view. Meanwhile, the distal ends of the distal protrusions 28 of some of the branches 20 (offset branches 24) protrude outside the slits 11a in plan view. In FIG. 12, in order to make the shape of the rectangle 410 easier to understand, for the sake of convenience, each side of the rectangle 410 is illustrated slightly offset outward from each corresponding side of the main body portion 11.

[0063] More specifically, in the example shown in Figure 12, among the multiple branch portions 20 of each of the first flexible printed circuit board 10a and the second flexible printed circuit board 10b, for two branch portions 20, the branch portion 20 located farther from the second reference position 520 in the first direction has a longer length dimension of the branch portion 20 from the base end of the branch portion 20 to the connection terminal 55. 12, the plurality of branch portions 20 of each of the first flexible printed circuit board 10a and the second flexible printed circuit board 10b include the above-mentioned offset branch portion 24. A portion of the offset branch portion 24 is contained within a rectangle 410 that circumscribes the main body portion 11 in a plan view. In addition, in Fig. 12, the third flexible printed circuit board 10c is omitted from the illustration of each flexible printed circuit board 10. However, among the multiple branching parts 20 of the third flexible printed circuit board 10c, the branching part 20 located farther from the reference position (second reference position 520) in the first direction may have a configuration in which the length dimension of the first direction extending part 22 is larger. Similarly, the multiple branching parts 20 of the third flexible printed circuit board 10c may include an offset branching part 24, and a part of some of the multiple branching parts 20 of the third flexible printed circuit board 10c (for example, the offset branching part 24) may be included in a rectangle 410 circumscribing the main body part 11 in a plan view.

[0064] <Modifications 1 and 2 of the second embodiment> Next, first and second modifications of the second embodiment will be described with reference to FIGS. 13(a) and 13(b). The voltage monitoring module 100 of this modified example differs from the voltage monitoring module 100 of the first embodiment described above in the points described below, but in other respects is configured in the same way as the voltage monitoring module 100 of the first embodiment described above.

[0065] 13(a), the branch portion 20 located at one end side in the first direction (the left end side in this modification) has a protrusion 26a protruding in the first direction from one end of the main body portion 11 in the first direction, a primary extension portion 31 extending from the tip of the protrusion 26a in a second direction (rearward in this modification) perpendicular to both the normal direction of the main body portion 11 and the first direction, a first direction extension portion 22a extending from the tip of the primary extension portion 31 in a direction opposite to the protrusion direction of the protrusion 26, and a tip protrusion 28a protruding in the second direction from the tip of the first direction extension portion 22a. The tip protrusion 28a has a connection terminal 55. In this way, in the present invention, the branch portion 20 may be arranged in the same direction as the movement direction of the cell terminal 220 when the battery cell 210 expands. Even with this configuration, the connection terminal 55 can smoothly follow the movement of the cell terminal 220 accompanying the contraction or expansion of the battery cell 210.

[0066] In the case of the modified example 2 shown in FIG. 13(b), the branch portion 20 located at one end side in the first direction (the left end side in the case of this modified example) includes a protruding portion 26b protruding from the main body portion 11 in a second direction (rearward in the case of this modified example) perpendicular to both the normal direction of the main body portion 11 and the first direction, a primary extending portion 31a extending in the first direction from the tip end of the protruding portion 26b beyond one end (the left end in the case of this modified example) of the main body portion 11 in the first direction, and a primary extending portion 31b extending in the first direction from the tip end of the protruding portion 26b. The connector 1 includes a secondary extending portion 33 extending from a tip end of the main body 11 in a direction opposite to the protruding direction of the protruding portion 26b (forward in this modified example), beyond the edge of the main body 11 in the second direction (rear edge in this modified example), a first direction extending portion 22b extending from a tip end of the secondary extending portion 33 in a direction opposite to the extending direction of the primary extending portion 31a, and a tip protruding portion 28b protruding from a tip end of the first direction extending portion 22b in a direction opposite to the protruding direction of the protruding portion. The tip protruding portion 28b has a connection terminal 55. Thus, in the present invention, the branch portion 20 may be routed around one end of the main body portion 11. Even with such a configuration, the connection terminal 55 can smoothly follow the movement of the cell terminal 220 accompanying the contraction or expansion of the battery cell 210. Here, the branch portion 20 located on one end side in the first direction (the left end side in this modified example) refers to the branch portion 20 located furthest from the first end side among the multiple branch portions 20.

[0067] <Modification 3 of the second embodiment> Next, a third modified example of the second embodiment will be described with reference to FIG. The voltage monitoring module 100 of this modified example differs from the voltage monitoring module 100 of the first embodiment described above in the points described below, but in other respects is configured in the same way as the voltage monitoring module 100 of the first embodiment described above.

[0068] In this modified example, the main body portions 11 of multiple flexible printed circuit boards 10 are connected to each other via connecting portions 17 extending in a second direction perpendicular to both the normal direction of the main body portions 11 and the first direction. With this configuration, the structural strength of the voltage monitoring module 100 can be sufficiently ensured. Here, "the main body portions 11 of the multiple flexible printed circuit boards 10 are connected to each other via the connecting portions 17" means that the main body portions 11 of each of the multiple flexible printed circuit boards 10 are directly connected to the connecting portions 17, that is, the main body portions 11 are directly connected to each other via the connecting portions 17. More specifically, the main body portions 11 of the multiple flexible printed circuit boards 10 are punched out integrally with each other.

[0069] More specifically, as shown in FIG. 14, in this modified example, among the multiple flexible printed circuit boards 10, the left end portion of the first flexible printed circuit board 10a and the left end portion of the second flexible printed circuit board 10b are connected to each other via a connecting portion 17. 14, the third flexible printed circuit board 10c is omitted. However, in the present invention, the third flexible printed circuit board 10c may be connected to other flexible printed circuit boards 10 via the connection parts 17. More specifically, in the present invention, for example, all of the flexible printed circuit boards 10 included in the voltage monitoring module 100 may be connected to each other via the connection parts 17, or some of the flexible printed circuit boards 10 may be connected to each other via the connection parts 17.

[0070] Third Embodiment Next, a third embodiment will be described with reference to FIGS. The voltage monitoring module 100 of this embodiment differs from the voltage monitoring module 100 of the first and second embodiments described above in the points described below, but in other respects is configured similarly to the voltage monitoring module 100 of the first and second embodiments described above.

[0071] In this embodiment, as shown in FIGS. 15 and 16, the voltage monitoring module 100 includes a rigid plate-like member 60 to which a main body 11 is attached. With this configuration, the structural strength of the main body 11 can be sufficiently ensured.

[0072] More specifically, in this embodiment, the end portion of the main body portion 11 of one or more flexible printed circuit boards 10 on the side having the corresponding partition extension portion 12 and the portion between the corresponding partition extension portion 12 and the expansion portion 80 in the main body portion 11 of the flexible printed circuit board 10 are each fixed (directly or indirectly) to the battery cell 210 via a rigid plate-like member 60. With this configuration, in one or more flexible printed circuit boards 10, a configuration can be more reliably realized in which expansion and contraction of the battery cells 210 in the section 250 corresponding to other flexible printed circuit boards 10 is absorbed by the expansion / contraction section 80 of the other section extension portion 13, and fluctuations of the cell terminals 220 of the corresponding section 250 are absorbed by the multiple branch portions 20 formed in the corresponding section extension portion 12.

[0073] More specifically, in this embodiment, the voltage monitoring module 100 has a pair of first reinforcing plates 61 as the plate-like member 60. The material forming the pair of first reinforcing plates 61 is not particularly limited, but one example is a hard resin material. Each of the pair of first reinforcing plates 61 is formed in a rectangular shape that is elongated in the second direction in a plan view. Each of the pair of first reinforcing plates 61 is attached along the lower surface (the surface on the battery pack 200 side) of the main body 11. For example, a rear end portion of each of the pair of first reinforcing plates 61 protrudes rearward from the main body 11 in a plan view. Of the pair of first reinforcing plates 61, one of the first reinforcing plates 61 is attached to an end portion (in the case of this embodiment, the right end portion) of the main body portion 11 of the flexible printed circuit board 10 on the side having the corresponding section extension portion 12, and the end portion is fixed to the partition plate 260 (and thus the battery cell 210) via the one of the first reinforcing plates 61. Of the pair of first reinforcing plates 61, the other of the pair of first reinforcing plates 61 is attached to a portion (in the case of this embodiment, the middle portion) between the corresponding section extension portion 12 and the stretchable portion 80 in the main body portion 11 of the flexible printed circuit board 10 (same as above), and the middle portion is fixed to the partition plate 260 (and thus the battery cell 210) via the other of the first reinforcing plates 61. In FIG. 15, the partition plate 260 is illustrated by a two-dot chain line. However, in the present invention, the pair of first reinforcing plates 61 may be fixed directly to the corresponding battery cells 210. The method for fixing the pair of first reinforcing plates 61 to the main body 11 of the flexible printed circuit board 10 is not particularly limited, and they may be fixed by thermal caulking, or may be fixed using an adhesive or the like, for example. 15 and 16 show an example in which the first flexible printed circuit board 10a is attached to the plate-shaped member 60 (the pair of first reinforcing plates 61), but other flexible printed circuit boards 10 may be attached to the plate-shaped member 60 (the pair of first reinforcing plates 61). More specifically, in the present invention, for example, all of the flexible printed circuit boards 10 included in the voltage monitoring module 100 may be attached to the plate-shaped member 60 (the pair of first reinforcing plates 61), or some of the flexible printed circuit boards 10 may be attached to the plate-shaped member 60 (the pair of first reinforcing plates 61).

[0074] <Modification 1 of the third embodiment> Next, a first modified example of the third embodiment will be described with reference to FIG. The voltage monitoring module 100 of this modified example differs from the voltage monitoring module 100 of the third embodiment described above in the points described below, but in other respects is configured similarly to the voltage monitoring module 100 of the third embodiment described above.

[0075] In this modified example, the voltage monitoring module 100 may further include, as the plate-shaped member 60, a pair of first reinforcing plates 61, and a connecting plate 62 connecting the pair of first reinforcing plates 61 to each other. According to such a configuration, for example, without fixing the main body portion 11 to the battery pack 200 via a plate-like member 60 (more specifically, a pair of first reinforcing plates 61), it is possible to more reliably realize a configuration in which, in one or more flexible printed circuit boards 10, expansion and contraction of the battery cells 210 in the compartment 250 corresponding to another flexible printed circuit board 10 is absorbed by the expansion / contraction portion 80 of the other compartment extension portion 13, and fluctuations of the cell terminals 220 of the corresponding compartment 250 are absorbed by the multiple branch portions 20 formed in the corresponding compartment extension portion 12. More specifically, the connecting plate 62 extends linearly in the first direction, for example, and is provided between one first reinforcing plate 61 and the other first reinforcing plate 61 .

[0076] <Modification 2 of the third embodiment> Next, a second modified example of the third embodiment will be described with reference to FIG. The voltage monitoring module 100 of this embodiment differs from the voltage monitoring module 100 of the above-described third embodiment and variant 1 in the respects described below, but is otherwise configured in the same manner as the voltage monitoring module 100 of the above-described third embodiment and variant 1.

[0077] In this modified example, as shown in FIG. 18, the voltage monitoring module 100 includes, as the plate-like member 60, one second reinforcing plate 63 that extends linearly in the first direction. With this configuration, the structural strength of the main body 11 can be sufficiently ensured. More specifically, the second reinforcing plate 63 extends over the entire area in the longitudinal direction of the flexible printed circuit board 10, and the entire main body 11 of the flexible printed circuit board 10 is disposed on the upper surface of the second reinforcing plate 63. The material constituting the second reinforcing plate 63 is not particularly limited, but one example is a hard resin material. 18, the end portion (the right end portion in this modified example) of the main body portion 11 of the flexible printed circuit board 10 on the side having the corresponding section extension portion 12 is fixed to the second reinforcing plate 63 by thermal caulking. Similarly, the portion (the middle portion in this modified example) between the corresponding section extension portion 12 and the stretchable portion 80 in the main body portion 11 of the flexible printed circuit board 10 is fixed to the second reinforcing plate 63 by thermal caulking. More specifically, as an example, a thermal crimping portion 18 is formed at each of the right end portion and the middle portion of the main body portion 11, and the main body portion 11 is fixed to the plate-like member 60 (second reinforcing plate 63) by the thermal crimping portion 18. A protrusion portion (not shown) is formed on the upper surface of the second reinforcing plate 63, and a through hole (not shown) is formed in the main body portion 11 at a portion corresponding to the protrusion portion. Then, with the protrusion portion of the second reinforcing plate 63 inserted into the through hole of the main body portion 11, the tip portion of the protrusion is crushed by thermal crimping, and the outer diameter is made larger than the inner diameter of the through hole. As a result, the thermal crimping portion 18 is formed, and the protrusion portion of the plate-like member 60 is prevented from coming off from the main body portion 11. 18 shows an example in which the first flexible printed circuit board 10a is attached to the plate-shaped member 60 (second reinforcing plate 63), but other flexible printed circuit boards 10 may be attached to the plate-shaped member 60 (second reinforcing plate 63). More specifically, in the present invention, for example, all of the flexible printed circuit boards 10 included in the voltage monitoring module 100 may be attached to the plate-shaped member 60 (second reinforcing plate 63), or some of the flexible printed circuit boards 10 may be attached to the plate-shaped member 60 (second reinforcing plate 63).

[0078] [Fourth embodiment] Next, a fourth embodiment will be described with reference to Figures 19, 20(a) and 20(b). Figure 19 is a perspective view of the voltage monitoring module 100 as viewed from the bottom side. The voltage monitoring module 100 of this embodiment differs from the voltage monitoring modules 100 of the first to third embodiments described above in the points described below, but is otherwise configured in the same way as the voltage monitoring modules 100 of the first to third embodiments described above.

[0079] In this embodiment, a case 65 is provided for housing the stretchable portion 80 of one or more flexible printed circuit boards 10, and the case 65 regulates the bulging of the stretchable portion 80 in the normal direction to other parts of the main body portion 11. Here, the "normal direction of the other part of the stretchable portion 80" means the normal direction of the part of the stretchable portion 80 that is not folded back and extends substantially flat. Also, "restraining the expansion" means that the stretchable portion 80 is restrained in a folded-back shape. According to such a configuration, the expansion / contraction section 80 can expand and contract in accordance with the expansion and contraction of the battery cell 210 while favorably maintaining the shape folded back in the first direction.

[0080] Furthermore, in this embodiment, the folding start point 80 a of the stretchable portion 80 is fixed to the case 65 . According to such a configuration, the stretchable portion 80 can be stretched with good reproducibility using the folding start point 80a as a reference. As described above, in the present invention, the "starting point 80a of the fold" means the position where the other-section extending portion 13 starts to rise from a state in which it extends flat.

[0081] More specifically, the case 65 includes, for example, a top surface portion 65a arranged along a plane located on the upper side of the telescopic portion 80, a bottom surface portion 65b arranged along a plane located on the lower side of the telescopic portion 80, and a pair of side surface portions (not shown) that cover the sides of the telescopic portion 80 and connect the top surface portion 65a and the bottom surface portion 65b to each other. According to this configuration, the top surface portion 65a can restrict the upward bulging of the expandable portion 80, and the bottom surface portion 65b can restrict the downward bulging of the expandable portion 80. In addition, the pair of side surface portions can also restrict the lateral projection of the expandable portion 80. Each of the top surface portion 65a and the bottom surface portion 65b is formed in a flat plate shape and extends linearly in the first direction. However, a part of the left end portion of the bottom surface portion 65b, for example, forms a step portion. Note that the part of the left end portion of the bottom surface portion 65b does not necessarily have to form a step portion. As shown in FIG. 19, the case 65 is fixed to the expansion and contraction portion 80 by, for example, the thermal caulking portion 18. More specifically, in the other section extending portion 13, a portion near the start point 80a of the fold in the stretching portion 80 and to the left of the start point is fixed to the bottom surface portion 65b via the thermal crimping portion 18. In addition, in the other section extending portion 13, a portion near the end point of the fold in the stretching portion 80 and to the left of the end point is fixed to the bottom surface portion 65b via the thermal crimping portion 18. It should be noted that the thermal crimping portion 18 is omitted in FIGS. 20(a) and 20(b). The material from which the case 65 is made is not particularly limited, but one example is a hard resin material.

[0082] In the present embodiment, the above-mentioned second reinforcing plate 63 may be fixed to the portion of each flexible printed circuit board 10 exposed from the case 65, as shown in FIG. According to this configuration, the shape of the expandable portion 80 is favorably maintained by the case 65, and the structural strength of each flexible printed circuit board 10 can be favorably secured.

[0083] As shown in FIGS. 20(a) and 20(b), in this embodiment, a folding start point 80a of an expandable portion 80 is fixed to the upper surface of a bottom portion 65b via an adhesive sheet 68. In the present invention, the method for fixing the folding starting point 80a of the expanding and contracting portion 80 to the case 65 is not limited to this example, and other methods such as adhesive or crimping may be used as appropriate. In the present invention, the folding start point 80a of the expandable portion 80 does not have to be fixed to the case 65, for example. 19, 20(a) and 20(b) show an example in which the expansion / contraction portion 80 of the first flexible printed circuit board 10a is housed in the case 65, but the expansion / contraction portions 80 of the other flexible printed circuit boards 10 may be housed in the case 65. More specifically, in the present invention, the expansion / contraction portions 80 of all the flexible printed circuit boards 10 included in the voltage monitoring module 100 may each be housed in the case 65, or only the expansion / contraction portions 80 of some of the flexible printed circuit boards 10 may be housed in the case 65.

[0084] Fifth embodiment Next, a fourth embodiment will be described with reference to FIG. The voltage monitoring module 100 of this embodiment differs from the voltage monitoring modules 100 of the first to fourth embodiments described above in the points described below, but is otherwise configured in the same manner as the voltage monitoring modules 100 of the first to fourth embodiments described above.

[0085] As shown in FIG. 21, in this embodiment, the voltage monitoring module 100 does not include a plurality of partition plates 260, and in the entire battery pack 200, the plate surfaces of adjacent battery cells 210 are arranged in surface contact with each other. The main body 11 of each flexible printed circuit board 10 is fixed to the corresponding battery cell 210 directly or indirectly (for example, via the above-mentioned plate-like member 60). More specifically, an end portion of the main body 11 of the first flexible printed circuit board 10a on the first reference position 510 side (the right end portion in this embodiment) is directly or indirectly fixed to the battery cell 210 located closest to the first reference position 510 among the battery cells 210 in the second section 250b. The second reference position 520a of the first flexible printed circuit board 10a is located at a position equivalent to or close to the battery cell 210 located closest to the first reference position 510 among the battery cells 210 in the second section 250b in the first direction. On the other hand, an end portion of the main body 11 of the first flexible printed circuit board 10a on the opposite side to the first reference position 510 side (the left end portion in this embodiment) is movable in a direction away from and toward the first reference position 510 in accordance with the expansion and contraction of the battery pack 200. More specifically, the left end portion of the main body portion 11 of the first flexible printed circuit board 10a is fixed, for example, directly or indirectly (for example, via the above-mentioned plate-shaped member 60 or cushioning material 320) to the battery cell 210 located furthest from the first reference position 510 among the battery cells 210 in the entire battery pack 200. Similarly, an end portion (the right end portion in this embodiment) of the main body portion 11 of the third flexible printed circuit board 10c on the first reference position 510 side is directly or indirectly fixed to the battery cell 210 located closest to the first reference position 510 among the battery cells 210 in the third section 250c. The second reference position 520c of the third flexible printed circuit board 10c is located at a position equivalent to or close to the battery cell 210 located closest to the first reference position 510 among the battery cells 210 in the third section 250c in the first direction. On the other hand, an end portion (the left end portion in this embodiment) of the main body portion 11 of the third flexible printed circuit board 10c on the opposite side to the first reference position 510 side is movable in a direction away from and toward the first reference position 510 in accordance with the expansion and contraction of the battery pack 200. More specifically, the left end portion of the main body portion 11 of the third flexible printed circuit board 10c is fixed directly or indirectly (same as above) to, for example, the battery cell 210 located furthest from the first reference position 510 among the battery cells 210 in the entire battery pack 200. An end portion (the right end portion in this embodiment) of the main body portion 11 of the second flexible printed circuit board 10b on the first reference position 510 side is not fixed to the battery pack 200. On the other hand, an end portion (the left end portion in this embodiment) of the main body portion 11 of the second flexible printed circuit board 10b on the opposite side to the first reference position 510 side is movable in a direction away from and toward the first reference position 510 following the expansion and contraction of the battery pack 200. More specifically, the left end portion of the main body portion 11 of the second flexible printed circuit board 10b is fixed directly or indirectly (same as above) to, for example, the battery cell 210 located on the farthest side from the first reference position 510 among the battery cells 210 of the entire battery pack 200. The second reference position 520b of the second flexible printed circuit board 10b is located at the same position as or in the vicinity of the battery cell 210 located on the farthest side from the first reference position 510 in the first direction.

[0086] Although the embodiments have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than those described above can also be adopted.

[0087] For example, in the above, an example has been described in which the cell terminal 220 is formed in a flat plate shape, but in the present invention, the shape of the cell terminal 220 is not limited to this example, and it may be formed in, for example, a cylindrical shape.

[0088] Furthermore, in the present invention, the first reference position 510 for the expansion and contraction of the battery cell 210 is not limited to a position at one end in the first direction, and may be, for example, a central position of the battery pack 200.

[0089] The present embodiment encompasses the following technical ideas. (1) A voltage monitoring module for monitoring a voltage state of a battery pack in which a plurality of compartments, each of which has a plurality of battery cells stacked in a first direction, are arranged in the first direction, a plurality of flexible printed circuit boards each corresponding to one of the plurality of sections; Each of the plurality of flexible printed circuit boards is A main body portion extending in the first direction; A plurality of branch portions each branching from the main body portion and arranged intermittently in the first direction; Equipped with the branch portion has a connection terminal at a tip end portion thereof that is connected to a cell terminal that is a terminal of the battery cell, The connection terminal of the branch portion of each flexible printed circuit board is connected to the cell terminal of the battery cell in the section corresponding to the flexible printed circuit board. (2) The main body portion of one or more of the flexible printed circuit boards is a corresponding section extension portion extending in the first direction along the section corresponding to the flexible printed circuit board; a second section extending in the first direction along the section corresponding to the second flexible printed circuit board; The voltage monitoring module according to (1) above. (3) The voltage monitoring module according to (2), wherein the corresponding section extension portion of one or more of the flexible printed circuit boards is formed to be wider than the other section extension portions of the flexible printed circuit board. (4) The branch portion includes a first direction extending portion extending in the first direction, A voltage monitoring module as described in any one of (1) to (3), wherein among the multiple branch portions, the branch portion located farther from the reference position in the first direction has a longer length dimension of the first direction extension portion. (5) The plurality of branch portions include an offset branch portion that is offset with respect to other branch portions in a second direction perpendicular to both the normal direction of the main body portion and the first direction, The voltage monitoring module according to any one of (1) to (4), wherein when viewed in the second direction, the offset branch portion and the other branch portion overlap each other in part. (6) A voltage monitoring module according to any one of (1) to (5), wherein a portion of some of the multiple branch portions is within a rectangle circumscribing the main body portion in a plan view. (7) A voltage monitoring module according to any one of (1) to (6), comprising a rigid plate-like member to which the main body is attached. (8) The voltage monitoring module according to any one of (1) to (7), wherein the main body portions of the multiple flexible printed circuit boards are separated from each other. (9) A voltage monitoring module described in any one of (1) to (8), wherein the main body portions of the multiple flexible printed circuit boards are connected to each other via connecting portions extending in a second direction perpendicular to both the normal direction of the main body portions and the first direction. (10) A voltage monitoring module according to any one of (1) to (3), The battery pack; Equipped with A battery unit in which each connection terminal of the flexible printed circuit board is connected to a corresponding cell terminal of the battery pack. (11) The main body portion of one or more of the flexible printed circuit boards is a corresponding section extension portion extending along the section corresponding to the flexible printed circuit board; a different section extension portion extending along the section corresponding to the different flexible printed circuit board; having The battery unit according to claim 10, wherein the other compartment extension portion has an expandable portion that is expandable in the first direction. (12) The battery unit according to (11), wherein the main body portion is folded back at the expansion section so that portions of the main body portion overlap each other. (13) The battery unit according to (12), wherein the main body portion is folded back in the first direction in a zigzag manner, at least one and a half round trips, in the expansion and contraction portion. (14) The battery unit according to (11), wherein the main body portion is curved in a normal direction to the other portion of the expandable portion. (15) A case is provided to house the stretchable portion of the one or more flexible printed circuit boards, The battery unit according to claim 13, wherein the case restricts the expansion of the expandable portion in a normal direction to other portions of the expandable portion in the main body. (16) The battery unit according to (15), wherein the starting point of the fold at the extension portion is fixed to the case. (17) A battery unit described in any one of (11) to (13), wherein an end portion of the main body portion of the one or more flexible printed circuit boards on the side having the corresponding partition extension portion and a portion of the main body portion of the flexible printed circuit board between the corresponding partition extension portion and the expansion portion are each fixed to the battery cell via a rigid plate-shaped member. [Explanation of symbols]

[0090] 10 Flexible Printed Circuit Board 10a First flexible printed circuit board 10b Second flexible printed circuit board 10c Third flexible printed circuit board 10d 4th flexible printed circuit board 11 Main body 11a Slit 12. Extension of the relevant section 13 Extension of other sections 17 Connecting part 18 Heat crimping part 20 Branch 22, 22a, 22b First direction extension part 24 Offset branch 26, 26a, 26b protrusion 28, 28a, 28b Tip protrusion 31, 31a Primary extension part 33 Secondary extension 35 Part 1 37 Part 2 40 Welded Plate 51 Wiring 55 Connection terminal 60 Plate-shaped member 61 First reinforcement plate 62 Connecting plate 63 Second Reinforcement Plate 65 cases 65a Top section 65b Bottom part 68 Adhesive Sheet 70 Busbar 72 External legs 74 Main Section 80 Telescopic part 80a starting point 81 Part 1 82 Part 2 90 Connector 100 Voltage Monitoring Module 200 Battery Pack 210 Battery Cell 220 Cell terminal 250 plots 250a Section 1 250b Section 2 250c Section 3 250d Section 4 260 Partition 260a First partition 260b Second partition plate 260c 3rd partition 260d 4th partition 300 Battery Unit 310 Case 320 Cushioning material 410 rectangle 510 1st reference position 520, 520a, 520b, 520c, 520d 2nd reference position AX axis

Claims

1. A voltage monitoring module for monitoring a voltage state of a battery pack in which a plurality of compartments, each of which has a plurality of battery cells stacked in a first direction, are arranged in the first direction, a plurality of flexible printed circuit boards each corresponding to one of the plurality of sections; Each of the plurality of flexible printed circuit boards is A main body portion extending in the first direction; A plurality of branch portions each branching from the main body portion and arranged at intervals in the first direction; Equipped with the branch portion has a connection terminal at a tip end portion thereof that is connected to a cell terminal that is a terminal of the battery cell, The connection terminal of the branch portion of each flexible printed circuit board is connected to the cell terminal of the battery cell in the section corresponding to the flexible printed circuit board.

2. The main body portion of one or more of the flexible printed circuit boards is a corresponding section extension portion extending in the first direction along the section corresponding to the flexible printed circuit board; an other section extension portion extending in the first direction along the section corresponding to the other flexible printed circuit board; 2. The voltage monitoring module of claim 1, comprising:

3. 3. The voltage monitoring module according to claim 2, wherein the corresponding section extension portion of one or more of the flexible printed circuit boards is formed to be wider than the other section extension portions of the corresponding flexible printed circuit boards.

4. The branch portion includes a first direction extending portion extending in the first direction, The voltage monitoring module according to claim 1 , wherein among the plurality of branch portions, a branch portion located farther from a reference position in the first direction has a longer length dimension of the first direction extending portion.

5. The plurality of branch portions include an offset branch portion that is offset with respect to other branch portions in a second direction perpendicular to both a normal direction of the main body portion and the first direction, The voltage monitoring module according to claim 1 , wherein the offset branch portion and the other branch portion partially overlap each other when viewed in the second direction.

6. The voltage monitoring module according to claim 1 , wherein a portion of some of the plurality of branch portions is within a rectangle circumscribing the main body portion in a plan view.

7. The voltage monitoring module according to claim 1 , further comprising a rigid plate-like member to which the main body is attached.

8. The voltage monitoring module according to claim 1 , wherein the main bodies of the plurality of flexible printed circuit boards are separated from each other.

9. 4. A voltage monitoring module as described in any one of claims 1 to 3, wherein the main body portions of the multiple flexible printed circuit boards are connected to each other via connecting portions extending in a second direction perpendicular to both the normal direction of the main body portions and the first direction.

10. A voltage monitoring module according to any one of claims 1 to 3; The battery pack; Equipped with A battery unit in which each connection terminal of the flexible printed circuit board is connected to a corresponding cell terminal of the battery pack.

11. The main body portion of one or more of the flexible printed circuit boards is a corresponding section extension portion extending along the section corresponding to the flexible printed circuit board; a different section extension portion extending along the section corresponding to the different flexible printed circuit board; having The battery unit according to claim 10 , wherein the other compartment extension portion has an expandable portion that is expandable and contractable in the first direction.

12. The battery unit according to claim 11 , wherein the main body is folded back at the expansion section so that parts of the main body overlap each other.

13. The battery unit according to claim 12 , wherein the main body is folded back in the expandable portion in a zigzag manner in the first direction for at least one and a half round trips.

14. The battery unit according to claim 11 , wherein the main body portion is curved in a normal direction of the other portion of the expandable portion.

15. a case that houses the stretchable portion of the one or more flexible printed circuit boards; The battery unit according to claim 13 , wherein the case restricts bulging of the expandable portion in a normal direction of the other portion of the expandable portion in the main body.

16. The battery unit according to claim 15 , wherein a starting point of the fold at the expansion section is fixed to the case.

17. The battery unit of claim 11, wherein an end portion of the main body portion of one or more of the flexible printed circuit boards on the side having the corresponding partition extension portion and a portion of the main body portion of the flexible printed circuit board between the corresponding partition extension portion and the expansion portion are each fixed to the battery cell via a rigid plate-shaped member.

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