Battery pack and method for manufacturing battery pack

Abstract

To provide a battery pack which can be manufactured by a simplified manufacturing process.SOLUTION: A battery pack 30 has a left holder 31L. The left holder 31L has a resin part 32 molded of a resin, and a plurality of lead plates 41 held by the resin part 32. The plurality of lead plates 41 includes a first lead plate 41 connected to a terminal 33a of a first battery cell 33, and a second lead plate 41 connected to the terminal 33a of the other battery cell 33. In the resin part 32, a through hole 32b penetrating through the resin part 32 in the lateral direction is formed. The through hole 32b is positioned between outer edges 41e of the two lead plates 41.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

[0001] The present disclosure relates to a battery pack and a method for manufacturing the battery pack. [Background technology]

[0002] Electric vehicles (including electric four-wheel vehicles, electric two-wheel vehicles, and electrically assisted bicycles) are equipped with battery packs consisting of multiple battery cells. For example, Patent Documents 1 and 2 listed below disclose battery packs having multiple cylindrical battery cells. The battery pack has multiple lead plates for connecting the terminals of the multiple battery cells. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-053205 [Patent Document 2] International Publication No. 2013 / 077205 Summary of the Invention [Problem to be solved by the invention]

[0004] In the battery pack manufacturing process, typically, multiple lead plates are aligned with multiple battery cells, and the battery cell terminals are welded to the lead plates. However, there are cases where the positions of the battery cells and the lead plates are misaligned, making the welding process difficult. In particular, when the number of battery cells and lead plates is large, the alignment work becomes complicated. [Means for solving the problem]

[0005] (1) The battery pack proposed in this disclosure includes a plurality of battery cells, each having a terminal at an end on a first side in a first direction, and a first holder including a resin portion disposed on the first side of the plurality of battery cells and molded from resin, and a plurality of lead plates held by the resin portion. The plurality of battery cells include a first battery cell and a second battery cell arranged in a second direction intersecting the first direction. The plurality of lead plates include a first lead plate connected to the terminal of the first battery cell and having a first edge, and a second lead plate connected to the terminal of the second battery cell and having a second edge facing the first edge in the second direction. The resin portion has a through hole formed therethrough in the first direction. The through hole is located between the first edge of the first lead plate and the second edge of the second lead plate.

[0006] This battery pack simplifies its manufacturing process. For example, a first holder can be formed by insert molding using a base material having multiple lead plates connected to each other, and then the connected lead plates can be separated by inserting a punch into a through hole. This reduces the number of press operations required to obtain multiple lead plates and the number of parts required for the press operations. Furthermore, by aligning the positions of the first holder and the battery cell, the positions of the multiple lead plates and the battery cell can be aligned. As a result, the welding process of the lead plates and the battery cell can be simplified.

[0007] (2) In the battery pack of (1), the first edge of the first lead-plate and the second edge of the second lead-plate may have a portion exposed inside the through-hole.

[0008] (3) In the battery pack of (1) or (2), the plurality of battery cells further includes a third battery cell. When the plurality of battery cells are viewed in the first direction, the first battery cell, the second battery cell, and the third battery cell may be located at three vertices of an equilateral triangle. When the plurality of battery cells are viewed in the first direction, the through hole may be located at the center of the equilateral triangle. This structure makes it easy to ensure a sufficient distance between the through hole and the battery cell.

[0009] (4) In the battery pack of (1) or (2), the plurality of battery cells further includes a third battery cell and a fourth battery cell. When the plurality of battery cells are viewed in the first direction, the first battery cell, the second battery cell, the third battery cell, and the fourth battery cell may be located at four vertices of a square. When the plurality of battery cells are viewed in the first direction, the through hole may be located at the center of the square. This structure makes it easy to ensure a sufficient distance between the through hole and the battery cells.

[0010] (5) In the battery pack of any one of (1) to (4), the first holder may have a signal line electrically connected to a circuit board and a third lead plate. The signal line may be arranged along a third edge of the third lead plate. The resin portion may have a through-hole formed therein, the through-hole penetrating the resin portion in the first direction and positioned between the signal line and the third edge of the third lead plate.

[0011] This structure enables a manufacturing method in which the left holder is formed by insert molding using a base material having a signal wire and lead plate connected to each other, and then the lead plate and signal wire are separated using a punch inserted into the through hole. Therefore, by aligning the positions of the first holder and the battery cell, the signal wire position can be optimized, making the battery pack assembly process easier.

[0012] (6) In the battery pack of (5), the signal line and the third edge of the third lead plate may have portions that are exposed inside the through hole.

[0013] (7) In the battery pack of any one of (1) to (6), a recess may be formed on the first edge of the first lead plate, and the inner edge of the recess formed on the first edge may be exposed inside the through hole. This structure can reduce the distance between the edges of two adjacent lead plates. As a result, the area of ​​each lead plate can be increased, and the electrical resistance of each lead plate can be reduced.

[0014] (8) In the battery pack of (7), a recess may be formed on the second edge of the second lead-plate, and the inner edge of the recess formed on the second edge may be exposed inside the through-hole. With this structure, the distance between the edges of two adjacent lead-plates can be further reduced.

[0015] (9) In the battery pack of any one of (1) to (6), the first edge of the first lead-plate may have a protrusion extending toward the second edge of the second lead-plate, and the protrusion may be exposed inside the through-hole.

[0016] (10) In the battery pack of (9), the second edge of the second lead-plate may have a recess formed therein, and the through-hole may be located between the first edge of the first lead-plate and the inner edge of the recess in the second edge. This structure reduces the distance between the edge of the first lead-plate and the edge of the second lead-plate. As a result, the area of ​​each lead-plate can be increased, and the electrical resistance of each lead-plate can be reduced.

[0017] (11) In the battery pack of any one of (1) to (10), each of the plurality of battery cells may have a terminal at an end portion on a second side in the first direction. The battery pack may have a second holder disposed on the second side of the plurality of battery cells and including a resin portion molded from resin and a plurality of lead plates held by the resin portion. The plurality of battery cells may include a fifth battery cell and a sixth battery cell. The plurality of lead plates of the second holder may include a fourth lead plate and a fifth lead plate. The resin portion of the second holder may have a through hole penetrating the resin portion in the first direction, and the through hole formed in the resin portion of the second holder may be located between an edge of the fourth lead plate and an edge of the fifth lead plate.

[0018] (12) A manufacturing method of a battery pack proposed in the present disclosure includes a step of preparing a substrate having a first lead plate, a second lead plate aligned with the first lead plate, and a connection portion connecting an edge of the first lead plate to an edge of the second lead plate; a molding step of forming a holder having a resin portion for holding the substrate by insert molding, and forming a through hole in the resin portion at a position corresponding to the connection portion; and a cutting step of cutting the connection portion with a punch inserted into the through hole.

[0019] This manufacturing method reduces the number of press operations required to obtain multiple lead plates and the number of parts required for press operations. Furthermore, by aligning the holder and battery cell positions, the positions of the multiple lead plates and the battery cells can be aligned. This simplifies the welding process for the lead plates and battery cells.

[0020] (13) The manufacturing method of (12) may include the steps of preparing a plurality of battery cells, each including a first battery cell and a second battery cell, each having a terminal at an end of a first side in a first direction; and placing the holder on the first side of the plurality of battery cells, welding the terminal of the first battery cell to the first lead plate, and welding the terminal of the second battery cell to the second lead plate.

[0021] (14) In the manufacturing method of (13), the plurality of battery cells may further include a third battery cell. When the plurality of battery cells are viewed in the first direction, the first battery cell, the second battery cell, and the third battery cell may be arranged at three vertices of an equilateral triangle, and the through hole may be formed at the center of the equilateral triangle in the molding step. This manufacturing method makes it easy to ensure a sufficient distance between the through hole and the battery cell.

[0022] (15) In the manufacturing method of (13), the plurality of battery cells may further include a third battery cell and a fourth battery cell. When the plurality of battery cells are viewed in the first direction, the first battery cell, the second battery cell, the third battery cell, and the fourth battery cell may be arranged at the four vertices of a square. In the molding step, the through hole may be formed at the center of the square. This manufacturing method makes it easy to ensure a sufficient distance between the through hole and the battery cell.

[0023] (16) In any of the manufacturing methods (12) to (15), the base may have a third lead plate, a signal wire arranged along an edge of the third lead plate, and a connection portion connecting the edge of the third lead plate and the signal wire. In the molding step, a through hole may be formed through the resin portion at a position corresponding to the connection portion, and in the cutting step, the connection portion may be cut using a punch inserted into the through hole. With this method, the signal wire can be positioned appropriately by aligning the holder and the battery cell, thereby facilitating the assembly of the battery pack. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a side view of an electric bicycle equipped with a battery pack proposed in the present disclosure. [Figure 2] FIG. 1 is a perspective view showing an example of a battery pack. [Figure 3] FIG. [Figure 4A] FIG. 2 is a perspective view of a left holder that constitutes the battery pack. [Figure 4B] FIG. 10 is a perspective view showing the inside (battery cell side) of the left holder. [Figure 5] FIG. 10 is an exploded perspective view showing the lead plates and battery cells of the left holder, and the lead plates of the right holder. [Figure 6] 10A and 10B are diagrams illustrating the positional relationship between a battery cell, a through hole formed in a resin part, and a welded part. [Figure 7] 10 is a diagram illustrating electrical connections between the lead plates of the left holder, the battery cell, and the lead plates of the right holder. FIG. [Figure 8] FIG. 4 is a flow chart for explaining a method for manufacturing a battery pack. [Figure 9A] 1 is a diagram showing an example of a substrate used in the manufacturing process of a battery pack, in which two adjacent lead plates are connected to each other, and adjacent lead plates and signal lines are also connected to each other. [Figure 9B] 9B is a diagram showing a state in which the lead plate and the signal line shown in FIG. 9A are separated. [Figure 10A] FIG. 9B is an enlarged view of an area X shown in FIG. 9A. [Figure 10B] This is an enlarged view of the region X shown in Figure 9B. The region X in Figure 9B is the same as the region X in Figure 9A. [Figure 11A] FIG. 9B is an enlarged view of region XI shown in FIG. 9A. [Figure 11B] This is an enlarged view of region XI shown in Figure 9B. Region XI in Figure 9B is the same as region XI in Figure 9A. [Figure 12A] FIG. 9B is an enlarged view of region XII shown in FIG. 9A. [Figure 12B] This is an enlarged view of region XII shown in Figure 9B. Region X in Figure 9B is the same as region X in Figure 9A. [Figure 13] 10B is a cross-sectional view of the left holder taken along line XIII-XIII in FIG. 10A for explaining a step of cutting the connection portion. FIG. [Figure 14] FIG. 10 is a diagram showing a modified example of the layout of the battery cells. DETAILED DESCRIPTION OF THE INVENTION

[0025] The battery pack and the manufacturing method of the battery pack proposed in this disclosure will be described below. Figure 1 is a side view of an electrically assisted bicycle 100, which is an example of a vehicle equipped with the battery pack proposed in this disclosure. The battery pack proposed in this disclosure may be mounted on an electric vehicle (a vehicle that runs solely on the driving force of an electric motor, such as an electric two-wheeled vehicle, an electric three-wheeled vehicle, or an electric four-wheeled vehicle).

[0026] As shown in Figure 1, a bicycle 100 has a crankshaft 2. A crank arm is attached to the end of the crankshaft 2. A pedal 2a is connected to the end of this crank arm. The crankshaft 2 is supported at the lower end of a seat tube 11. A saddle 18 is fixed to the upper end of the seat tube 11.

[0027] At the front of the bicycle 100 are provided a handlebar stem 8, a handlebar 7 fixed to the upper part of the handlebar stem 8, a front fork 19 fixed to the lower part of the handlebar stem 8, and a front wheel 9 supported at the lower end of the front fork 19. The handlebar stem 8 is supported by a head pipe 17a provided at the front end of a frame 17. The shape of the frame 17 is not limited to the example shown in FIG. 1 and may be modified as appropriate.

[0028] As shown in FIG. 1, bicycle 100 has a drive unit 20. Drive unit 20 has an electric motor that outputs a force (auxiliary torque) to assist in driving rear wheel 6, and a reducer. The electric motor is driven by power supplied from battery pack 30. In the example of bicycle 100, battery pack 30 is attached to the rear side of seat tube 11, and drive unit 20 is disposed behind crankshaft 2. The layout of drive unit 20 and battery pack 30 is not limited to the example of bicycle 100, and may be changed as appropriate.

[0029] The force applied to the crankshaft 2 through the pedals 2a is transmitted to the rear wheel 6, for example, via a chain 5. The power output from the drive unit 20 (torque of the electric motor) is also transmitted to the rear wheel 6 via the chain 5.

[0030] [Battery pack] 2 to 8 are diagrams showing a battery pack 30, an example of a battery pack proposed in this disclosure. In these figures, the directions indicated by Z1 and Z2 are referred to as upward and downward, respectively. Furthermore, the directions indicated by X1 and X2 are referred to as right and left, respectively, and the directions indicated by Y1 and Y2 are referred to as forward and backward, respectively. These directions are used to describe the relative positions and shapes of the parts, components, and elements that make up the battery pack 30, and do not limit the orientation of the battery pack 30 on the vehicle. Therefore, for example, the battery pack 30 may be mounted on the bicycle 100 so that the rear (Y2 direction) shown in FIG. 2 faces upward from the bicycle 100.

[0031] 3, the battery pack 30 has a plurality of battery cells 33, a left holder 31L, and a right holder 31R. The battery pack 30 may also have a center holder 34 and a circuit board 51. The battery pack 30 may also have a housing (not shown) that houses the battery cells 33 and the holders 31L and 31R.

[0032] [Battery cell] As shown in FIG. 3, the battery cells 33 have terminals 33a at their ends in the left-right direction. Some of the battery cells 33 are arranged so that the positive terminal 33a+ faces left and the negative terminal 33a- faces right. The remaining battery cells 33 are arranged so that the positive terminal 33a+ faces right and the negative terminal 33a- faces left. Each battery cell 33 may be cylindrical. The multiple battery cells 33 are aligned in two directions perpendicular to the left-right direction. More specifically, the multiple battery cells 33 are aligned in the front-to-back direction (Y1-Y2 direction) and in oblique directions inclined both in the front-to-back direction and the up-to-down direction (Z1-Z2 direction).

[0033] [Central holder] As shown in Fig. 3, the central holder 34 is formed with a plurality of holding holes 34a that penetrate it in the left-right direction. The plurality of battery cells 33 may be fitted into and held in the plurality of holding holes 34a. Unlike the example shown in the figure, the battery pack 30 does not need to have a central holder 34. In this case, the battery cells 33 may be held only by the left holder 31L and the right holder 31R, which will be described later.

[0034] [Left holder] Left holder 31L is disposed on the left side of the multiple battery cells 33. As shown in FIGS. 4A and 5, left holder 31L has a resin part 32 and multiple lead plates 41A to 41F.

[0035] Each of the lead plates 41A to 41F has multiple welds 41a. As shown in FIG. 5, for example, each of the lead plates 41A to 41F may have three welds 41a, and each of the lead plates 41B to 41E may have six welds 41a. Each weld 41a is welded to the left terminal 33a of the battery cell 33. A slit 41b (see FIG. 6) is formed in the weld 41a, and the inner edge of this slit 41b may be welded to the terminal 33a. As shown in FIG. 6, the slit 41b is, for example, a substantially H-shape rotated 90 degrees, but the shape is not limited to this and may be, for example, an I-shape.

[0036] 4B, a plurality of recesses 32a may be formed on the right surface (the surface facing the battery cells 33) of the resin part 32. The left portions of the plurality of battery cells 33 may be fitted into the plurality of recesses 32a, respectively.

[0037] Resin portion 32 and lead plates 41A to 41F are formed by insert molding. Lead plates 41A to 41F are held by resin portion 32. More specifically, portions of lead plates 41A to 41F other than welded portions 41a are embedded in the material of resin portion 32.

[0038] In insert molding, lead plates 41A-41F (more specifically, substrate 40L, described later) are placed in a cavity of a mold, and then molten resin (material for resin portion 32) is filled into the cavity. Examples of materials that can be used for resin portion 32 include polycarbonate (PC), ABS resin (Acrylonitrile Butadiene Styrene resin), a mixed resin of PC and ABS, polypropylene (PP), polyamide (PA), and polyphenylene sulfide (PPS). When the molten resin solidifies, resin portion 32 is formed, and lead plates 41A-41F are fixed to resin portion 32. Fasteners such as screws or bolts do not need to be used to fix lead plates 41A-41F to resin portion 32.

[0039] As shown in FIG. 7(a), the lead plates 41A-41F are arranged along a common plane and do not overlap one another when viewed in the left-right direction. The left holder 31L has, for example, six lead plates 41A-41F. In one example of the battery pack 30, lead plate 41A is arranged at the forefront. Lead plate 41B is located behind the lower part of lead plate 41A, and the front part of lead plate 41C is located above lead plate 41B. Lead plate 41D is located below the rear part of lead plate 41C, and lead plate 41E is located behind lead plate 41D. Lead plate 41F is located above the rear part of lead plate 41C. The number and layout of lead plates 41A-41F are not limited to the example described here. They may be changed as appropriate to suit the number, layout, and connection relationship of the battery cells 33.

[0040] As shown in FIG. 4A, the left holder 31L may have power terminals 43A-43F. The power terminals 43A-43F protrude outside the resin part 32. When the battery pack 30 is in use, the battery pack 30 supplies current to the drive unit 20 through the power terminals 43A-43F. As shown in FIG. 7(a), the power terminal 43A may be formed on, for example, the lead plate 41A. Also, the power terminal 43F may be formed on, for example, the lead plate 41F.

[0041] As shown in FIG. 4A, the left holder 31L may further have signal terminals 43B to 43E. The signal terminals 43B to 43E also protrude outside the resin portion 32. As shown in FIG. 7(a), the left holder 31L may have a plurality of signal wires 42B, 42D, and 42E. The signal wires 42B, 42D, and 42E extend from lead plates 41B, 41D, and 41E, respectively. The signal terminal 43B may be formed at an end of the signal wire 42B. Similarly, the signal terminal 43D may be formed at an end of the signal wire 42D, and the signal terminal 43E may be formed at an end of the signal wire 42E. The signal terminal 43C may extend from the lead plate 41C. The terminals 43A to 43F may be arranged at the front of the battery pack 30 and lined up in the front-to-rear direction.

[0042] As shown in FIG. 2, the signal terminals 43B to 42E may be connected to a circuit board 51. A control IC chip for monitoring the state of the battery cells 33 may be mounted on the circuit board 51. This IC chip may detect the voltages of the signal terminals 43B to 43E and monitor the state of the battery cells 33 (more specifically, the battery cells 33 to which the terminals 43B to 43E are connected via the signal lines 42B to 42E) based on the voltages. The power terminals 43A to 43F may also be electrically connected to the circuit board 51. The IC chip may detect the voltages of the power terminals 43A to 43F and monitor the state of the battery cells 33 based on the voltages.

[0043] In the following description, when the lead plates 41A to 41F are not distinguished from one another, the lead plates will be designated by the symbol "41." When the signal wires 42B to 42E are not distinguished from one another, the signal wires will be designated by the symbol "42." When the power terminals 43A to 43F and the signal terminals 43B to 43E are not distinguished from one another, the terminals will be designated by the symbol "43."

[0044] As will be described in detail later, in the insert molding, the outer edges 41e of two adjacent lead plates 41 (e.g., lead plates 41A and 41B) are connected to each other by connecting portions 44a, 44b, and 44e (see FIGS. 9A, 10A, and 11A). Therefore, the lead plates constitute a single metal plate (hereinafter referred to as "substrate 40L," see FIG. 9A). The signal lines 42 and the lead plates 41 also constitute the substrate 40L. After the substrate 40L is fixed to the resin portion 32 by insert molding, the connecting portions 44a, 44b, and 44e are cut by press processing, and the lead plates 41 are separated (cutting step, see FIG. 9B). To enable such press processing, the resin portion 32 has through-holes 32b (see FIG. 4A) penetrating it in the left-right direction. The through-holes 32b are formed at the positions of the connecting portions 44a, 44b, and 44e. During the press working, the connecting portions 44a, 44b, and 44e are cut off by a punch inserted into the through-hole 32b.

[0045] Note that multiple types of connecting portions 44a to 44e (see FIGS. 9A, 10A, 11A, and 12A) are used in substrate 40L (FIG. 9A) from which multiple lead plates 41 are made. In the following, when there is no need to distinguish between these types, the connecting portions will be referred to as "44."

[0046] [Right holder] As shown in FIG. 3, the right holder 31R is disposed to the right of the multiple battery cells 33. Like the left holder 31L, the right holder 31R has a resin part 32 and multiple lead plates 41G-41K (see FIG. 5). Each of the lead plates 41G-41K has multiple welds 41a. Each weld 41a is welded to a terminal 33a on the right side of the battery cell 33. Like the left holder 31L, the welds 41a may have a slit 41b formed in a roughly H-shape rotated by 90 degrees. The resin part 32 and lead plates 41G-41K of the right holder 31R are formed by insert molding, and the lead plates 41G-41K are held by the resin part 32.

[0047] Furthermore, a plurality of recesses 32a (see FIG. 3) may be formed on the left surface (the surface facing the battery cells 33) of the resin part 32. The right portions of the plurality of battery cells 33 may be fitted into the plurality of recesses 32a, respectively.

[0048] 7(b), the right holder 31R may have signal terminals 43G-43K. The signal terminals 43G-43K protrude to the outside of the resin part 32. Similar to the left holder 31L, the right holder 31R may have signal wires 42G-42K extending from the lead plates 41G-41K to the signal terminals 43G-43K.

[0049] 2, the signal terminals 43G-43K are connected to a circuit board 51. A control IC chip mounted on the circuit board 51 may detect the voltages of the signal terminals 43G-43K and monitor the battery cells 33 (more specifically, the battery cells 33 welded to the lead plates 41G-41K to which the terminals 43G-43K are connected via signal lines) based on the detected voltages.

[0050] In the following description, when the lead plates 41G to 41K are not distinguished from one another, the lead plates will be designated by the symbol "41." In the following description, when the signal wires 42G to 42K are not distinguished from one another, the signal wires will be designated by the symbol "42." In the following description, when the signal terminals 43G to 43K are not distinguished from one another, the signal terminals will be designated by the symbol "43."

[0051] Like the lead plates 41 of the left holder 31L, the multiple lead plates 41 of the right holder 31R are connected to one another by connection portions 44 during insert molding, forming a single metal plate (hereinafter referred to as the "substrate"). The signal wires 42 extending from the lead plates 41 also form the substrate together with the lead plates 41. After the substrate is fixed to the resin portion 32 by insert molding, the connection portions 44 are cut by press working, and the multiple lead plates 41 are separated (cutting process). To enable such press working, the resin portion 32 is formed with through holes 32b (see FIG. 3) that penetrate it in the left-right direction. Each through hole 32b is formed at the position of a connection portion 44. During press working, a punch is inserted into the through holes 32b, and the connection portions 44 are cut.

[0052] [Connection of multiple battery cells] In the battery pack 30, a plurality of battery cells 33 connected in parallel constitute one set. Then, a plurality of sets are connected in series. For example, in the battery pack 30, three battery cells 33 connected in parallel constitute one set. Then, ten sets are connected in series.

[0053] The electrical connections of the battery cells 33 will be described with reference to Figure 7. Figure 7(a) shows the lead plate 41 of the left holder 31L. Figure 7(b) shows the lead plate 41 of the right holder 31R.

[0054] In this figure, the positions of the welds 41a on the lead plates 41 are indicated by the subscripts of the battery cells 33 to which they are welded. For example, the symbol "33_1(+)" in FIG. 7(a) indicates that the weld 41a at this position is welded to the positive terminal 33a+ of the first set of battery cells 33. Similarly, the symbol "33_2(-)" indicates that the weld 41a at this position is welded to the negative terminal 33a- of the second set of battery cells 33. Furthermore, in FIG. 7(b), the symbol "33_1(-)" indicates that the weld 41a at this position is welded to the negative terminal 33a- of the first set of battery cells 33.

[0055] 7(a), the power terminal 43A (positive terminal of the battery pack 30) of the battery pack 30 is formed on the lead-plate 41A. The power terminal 43F (negative terminal of the battery pack 30) is formed on the lead-plate 41F. Between the lead-plate 41A and the lead-plate 41F, the lead-plates 41B to 41E of the left holder 31L, the lead-plates 41G to 41K of the right holder 31R, and the battery cells 33 are electrically connected in the following order (1) to (23).

[0056] (1) Power terminal 43A, (2) Lead plate 41A of left holder 31L, (3) First set of three battery cells 33, (4) Lead plate 41G of right holder 31R, (5) Second set of three battery cells 33, (6) Lead plate 41B of left holder 31L, (7) Third set of three battery cells 33, (8) Lead plate 41H of right holder 31R, (9) Fourth set of three battery cells 33, (10) Lead plate 41C of left holder 31L, (11) Fifth set of three battery cells 33, (12) Lead plate 41C of right holder 31R (13) the sixth set of three battery cells 33, (14) the lead plate 41D of the left holder 31L, (15) the seventh set of three battery cells 33, (16) the lead plate 41J of the right holder 31R, (17) the eighth set of three battery cells 33, (18) the lead plate 41E of the left holder 31L, (19) the ninth set of three battery cells 33, (20) the lead plate 41K of the right holder 31R, (21) the tenth set of three battery cells 33, (22) the lead plate 41F of the left holder 31L, and (23) the power terminal 43F.

[0057] The lead plate 41A of the left holder 31L has three welds 41a to which the positive terminals 33a+ of the three battery cells 33 are respectively welded. The lead plate 41F has three welds 41a to which the negative terminals 33a- of the three battery cells 33 are respectively welded. In contrast, each of the lead plates 41B to 41E has six welds 41a. Three of the welds 41a are welded to the positive terminals 33a+ of the three battery cells 33, and the remaining three are welded to the negative terminals 33a- of the three battery cells 33. Similarly, each of the lead plates 41G to 41K of the right holder 31R has three welds 41a to which the positive terminals 33a+ of the three battery cells 33 are respectively welded, and three welds 41a to which the negative terminals 33a- of the three battery cells 33 are respectively welded.

[0058] The number of battery cells 33 constituting each group is not limited to three, but may be two or more than three. The number of groups connected in series may be less than ten or more than ten.

[0059] [Battery pack manufacturing method] A method for manufacturing the battery pack 30 will be described with reference to FIG.

[0060] A single base material 40L including a plurality of lead plates 41 and signal lines 42 of the left holder 31L is prepared (S101). For example, a plurality of base materials 40L may be cut out from a single rectangular metal plate by press working (punching).

[0061] 9A is a diagram showing an example of such a substrate 40L. As shown in the figure, the outer edges 41e of two adjacent lead plates 41 are connected to each other. This structure can reduce the number of press processes required to obtain multiple lead plates 41 and the number of parts required for press processes. FIG. 9B is a diagram showing lead plates 41 and signal wires 42 separated by press processes (cutting process in S103) performed after insert molding.

[0062] [Connection between two lead plates] 10A and 11A are enlarged views of region X and region XI in FIG. 9A, respectively. As shown in FIG. 10A, the outer edge 41e of lead plate 41B and the outer edge 41e of lead plate 41C are connected to each other by a connecting portion 44a. The connecting portion 44a extends from the outer edge 41e of one lead plate 41B to the outer edge 41e of the other lead plate 41C along a plane parallel to the base material 40L.

[0063] 11A, the outer edge 41e of the lead plate 41A and the outer edge 41e of the lead plate 41B may be connected by a connecting portion 44b. The connecting portion 44b extends from the outer edge 41e of one lead plate 41A toward the outer edge 41e of the other lead plate 41B along a plane parallel to the substrate 40L. A recess 41f is formed in the outer edge 41e of the lead plate 41B. This recess 41f will be described later.

[0064] Outer edge 41e of lead plate 41C is connected to outer edge 41e of lead plate 41D. Similarly, outer edge 41e of lead plate 41D is connected to outer edge 41e of lead plate 41E, and outer edge 41e of lead plate 41E is connected to outer edge 41e of lead plate 41F.

[0065] Two adjacent lead plates 41 may be connected to each other by multiple connection portions 44. This can increase the strength of the base material 40L. For example, lead plates 41A and 41B are connected to each other by two connection portions 44b. Lead plates 41B and 41C are also connected to each other by two connection portions 44a.

[0066] Furthermore, one lead plate 41 may be connected to multiple adjacent lead plates 41. For example, lead plate 41B is connected to lead plate 41A located in front of lead plate 41B, lead plate 41C located above lead plate 41B, and lead plate 41D located behind lead plate 41B. This allows the substrate 40L to be used in manufacturing a battery pack 30 with a large number of lead plates 41.

[0067] [Connection between signal wire and lead plate] As described above, the left holder 31L has signal wires 42 extending from the lead plates 41. The signal wires 42 may be arranged along the outer edge 41e of another lead plate 41 and connected to the outer edge 41e of this other lead plate 41. This makes it possible to prevent the signal wires 42 from shifting in position within the cavity of a mold when insert molding (S102), which will be described later, is performed.

[0068] 12A, the signal line 42D may be arranged along the outer edge 41e of the lead plate 41C. The outer edge 41e of the lead plate 41C and the signal line 42D are connected to each other by a connecting portion 44c. Similar to the connecting portion 44a described above, the connecting portion 44c extends along a plane parallel to the base material 40L.

[0069] The outer edge 41e of the lead-plate 41C and the signal wire 42D may be connected by a plurality of connecting portions 44c arranged at intervals along the outer edge 41e of the lead-plate 41C. Also, as shown in Fig. 12A, the signal wire 42E may be connected to the outer edge 41e of the lead-plate 41F by a plurality of connecting portions 44c, similar to the signal wire 42D.

[0070] [Connection between two signal lines] A plurality of signal wires 42 may be arranged between the outer edges 41e of the two lead plates 41. In this case, the plurality of signal wires 42 may be connected to each other via a connecting portion 44. In the example shown in FIG. 12A, two signal wires 42D and 42E are arranged between the outer edges 41e of lead plates 41F and 41e of lead plates 41C. The two signal wires 42D and 42E are connected to each other by a connecting portion 44d (see FIGS. 9A and 12A). With this structure, even when there are a large number of signal wires 42, it is possible to prevent the signal wires 42 from shifting in position.

[0071] 12A, there may be only one signal line 42 disposed between two lead plates 41. In this case, this single signal line 42 may be connected to only one of the two lead plates 41 or to both of them.

[0072] [Insert molding] The left holder 31L is formed by insert molding using the base material 40L (S102). That is, after the base material 40L is placed in a cavity of a mold, the cavity is filled with molten resin (the material of the resin portion 32) to obtain the resin portion 32 that holds the base material 40L. At this time, through holes 32b that penetrate the resin portion 32 in the left-right direction are formed at positions corresponding to the multiple connection portions 44. The connection portions 44 are exposed to the right and left sides of the left holder 31L through the through holes 32b. Furthermore, in the step of S102, multiple fastening holes 32e (see FIG. 4A) that penetrate the resin portion 32 may be formed.

[0073] [Cutting process] Next, the connection portions 44 are cut by pressing (more specifically, punching) to separate the multiple lead plates 41 and signal wires 42 that were connected to each other (S103). Figure 13 is a cross-sectional view illustrating this cutting process. Figure 13 shows, for example, a cross section of the left holder 31L taken along line XIII-XIII in Figure 10A.

[0074] As shown in FIG. 13(a), the through-hole 32b may have a small-diameter portion 32b1 and a large-diameter portion 32b2. As described above, the connection portions 44 are exposed to the right and left sides of the left holder 31L through the through-hole 32b. As shown in FIG. 13(b), a die 91 having a recess 91a formed therein is inserted into the large-diameter portion 32b2, and a punch 92 is inserted into the small-diameter portion 32b1. This cuts each connection portion 44. As a result, two adjacent lead plates 41 are separated, as shown in FIG. 13(c). The shape and structure of the punch 92 are not particularly limited as long as it can cut the cutting portions 44.

[0075] In the left holder 31L formed in this manner, the through hole 32b is located between the outer edges 41e of two adjacent lead plates 41. More specifically, the center C1 (see FIG. 13(c)) of the through hole 32b is located between the outer edges 41e of two adjacent lead plates 41. The outer edges 41e of one lead plate 41 and the other lead plate 41 have portions exposed inside the through hole 32b of the resin part 32 (see FIG. 13(c)).

[0076] In the cutting step of S103, a plurality of connection portions 44 may be cut simultaneously, that is, a plurality of connection portions 44 may be cut by pressing once.

[0077] 13A and 13B, the connection portions 44 connecting the signal wires 42 and the lead plates 41 are also cut in the same manner as in the example shown in Fig. 13A. As a result, a plurality of through holes 32b aligned along the outer edge 41e of the lead plate 41 are formed between the signal wires 42 and the outer edge 41e of the lead plate 41. That is, the center C1 (see Fig. 13C) of each through hole 32b is positioned between the signal wires 42 and the outer edge 41e of the lead plate 41. Furthermore, the signal wires 42 and the outer edge 41e of the lead plate 41 have portions exposed inside the through holes 32b.

[0078] [Right holder] The right holder 31R is manufactured in the same manner as the left holder 31L. Specifically, first, a single base material including a plurality of lead plates 41 and a plurality of signal wires 42 of the right holder 31R is prepared (S104). In this base material, as in the base material 40L, the outer edges 41e of two adjacent lead plates 41 may be connected to each other. Furthermore, the signal wires 42 may be connected to the outer edges 41e of the lead plates 41. Furthermore, two adjacent signal wires 42 may be connected to each other.

[0079] Next, the right holder 31R is formed by insert molding using the base material prepared in S104 (S105). At this time, through holes 32b that penetrate the resin part 32 in the left-right direction are formed at positions corresponding to the multiple connection parts 44. Furthermore, multiple fastening holes 32e (see FIG. 3) may be formed in the resin part 32 during the molding in S105.

[0080] Next, the connection portions 44 are cut by pressing (more specifically, punching) to separate the lead plates 41 and the signal wires 42 that have been connected to each other (S106). Note that in the cutting step of S106, multiple connection portions 44 may be cut simultaneously. That is, multiple connection portions 44 may be cut by a single press.

[0081] [Combination process] Next, the plurality of battery cells 33 are fitted into the plurality of holding holes 34a (see FIG. 3) formed in the central holder 34 (S107). Then, the battery cells 33, the left holder 31L, and the right holder 31R are combined together in the left-right direction (S108). At this time, fasteners such as bolts and nuts may be inserted into the fastening holes 32e formed in the resin parts 32 of the holders 31L and 31R to secure the holders 31L and 31R to each other. Note that the combining process is not limited to the above-described procedure. For example, the plurality of battery cells 33 may be fitted into the left holder 31L (or the right holder 31R), and then the plurality of battery cells 33 may be fitted into the central holder 34, and then the right holder 31R (or the left holder 31L) may be combined.

[0082] [Welding process] Thereafter, the welded portion 41a of the left holder 31L is welded to the left terminal 33a of the battery cell 33, and the welded portion 41a of the right holder 31R is welded to the right terminal 33a (S109). In this way, the battery pack 30 is obtained.

[0083] In S109, when the left holder 31L and the battery cell 33 are aligned, the positions of the multiple lead plates 41 on the left holder 31L will match the positions of the battery cell 33. When the right holder 31R and the battery cell 33 are aligned, the positions of the multiple lead plates 41 on the right holder 31R will match the positions of the battery cell 33. This makes the welding work easier.

[0084] [Connection details] The connection portion 44 between two adjacent lead plates 41 and the connection portion 44 between the lead plate 41 and the signal line 42 will be described in detail below.

[0085] As shown in Fig. 10A, the outer edges 41e of two adjacent lead plates 41 may be connected to each other by a relatively short connecting portion 44a. The connecting portion 44a may be shorter than the diameter of the through-hole 32b (more specifically, the diameter of the small-diameter portion 32b1), for example. When the connecting portion 44a has such a length, the entire connecting portion 44a may be cut as a result of the cutting steps shown in S103 to S106 of Fig. 8, as shown in Fig. 10B.

[0086] Furthermore, as a result of this cutting process, recesses 41g (see FIG. 10B) may be formed in the outer edges 41e of one lead plate 41 and the other lead plate 41. By using such connection portions 44a, the distance between the outer edges 41e of two adjacent lead plates 41 can be reduced. As a result, the area of ​​the lead plate 41 can be increased, and the electrical resistance of the lead plate 41 can be reduced. In the finally obtained battery pack 30, the inner edges of the recesses 41g are exposed inside the through-holes 32b formed in the resin portion 32.

[0087] 11A, a recess 41f may be formed in the outer edge 41e of one lead plate 41 (41B). The connection portion 44b may extend from the outer edge 41e of the other lead plate 41 (41A) and connect to the inside of this recess 41f. This structure also allows the distance between the outer edges 41e of two adjacent lead plates 41 to be reduced. Furthermore, the length of the connection portion 44b can be ensured sufficiently. Furthermore, because the distance between the two outer edges 41e is short, the area of ​​the lead plate 41 can be increased, and the electrical resistance of the lead plate 41 can be reduced.

[0088] When the lead plates 41 are connected as shown in FIG. 11A, the cutting steps S103 to S106 in FIG. 8 result in only a portion of the connection portion 44b being cut off, as shown in FIG. 11B. A portion of the connection portion 44b (protrusion 41h) may remain on the outer edge 41e of one lead plate 41 (41A). A portion of the connection portion 44b (protrusion 41i) may also remain on the outer edge 41e of the other lead plate 41 (41B). In this case, the through hole 32b may be located between the outer edge 41e of one lead plate 41 (41A) and the inner edge of the recess 41f of the other lead plate 41 (41B). More specifically, the center C1 (FIG. 13(c)) of the through hole 32b may be located between the outer edge 41e of one lead plate 41 (41A) and the inner edge of the recess 41f of the other lead plate 41 (41B). In the battery pack 30 that is finally obtained, the protrusions 41h and 41i are exposed inside the through-holes 32b formed in the resin part 32.

[0089] If the distance between outer edges 41e of two adjacent lead plates 41 is large, recess 41g shown in Fig. 10B and recess 41f shown in Fig. 11A may not be formed. For example, as shown in Fig. 9A, lead plates 41E and 41F may be connected to each other via connecting portion 44e. In this case, as shown in Fig. 9B, only a portion of connecting portion 44e may be cut in the cutting steps shown in S103-S106 of Fig. 8.

[0090] The connection portions 44a, 44b, and 44e described above may be applied to the connection of the other lead plates 41D, 41E, and 41F.

[0091] As shown in Fig. 12A, the lead plate 41 (41C) and the signal line 42 (42D) may also be connected to each other by a relatively short connection portion 44c. The connection portion 44c may be shorter than the diameter of the through hole 32b (more specifically, the diameter of the small diameter portion 32b1), for example. When the length of the connection portion 44c is such, the entire connection portion 44c may be cut as a result of the cutting steps shown in S103 to S106 of Fig. 8, as shown in Fig. 12B.

[0092] Furthermore, as a result of this cutting process, recesses 41j (see FIG. 12B) may be formed in outer edges 41e of lead plates 41, and recesses 42a (see FIG. 12B) may be formed in edges of signal wires 42. This structure reduces the distance between outer edges 41e of lead plates 41 and signal wires 42. As a result, the area of ​​lead plates 41 can be increased, and the thickness of signal wires 42 can also be increased, thereby reducing their electrical resistance. This connection structure may be applied to connection structures between other signal wires and lead plates (for example, a connection structure between signal wire 42E and lead plate 41F).

[0093] [Through hole position] The battery cells 33 arranged in the front-to-rear direction form multiple columns. As shown in FIG. 5, the battery cells 33 form a first column S1, a second column S2, a third column S3, and a fourth column S4. The positions of the battery cells 33 arranged in two adjacent columns are offset in the front-to-rear direction. As a result, as shown in FIG. 6, when the battery cells 33 are viewed in the left-to-right direction, three adjacent battery cells 33 are located at the vertices n1 to n3 of an equilateral triangle T. For example, the centers of the three battery cells 33 may be located at the vertices n1 to n3 of the equilateral triangle T. This arrangement of the battery cells 33 can increase the arrangement density of the battery cells 33, thereby enabling the battery pack 30 to be made more compact.

[0094] Note that "battery cells 33 are located at vertices n1 to n3 of an equilateral triangle T" does not necessarily mean that the position of the center C of the battery cell 33 and the positions of the vertices n1 to n3 are exactly the same. In other words, the position of the center C of the battery cell 33 may be shifted from the positions of the vertices n1 to n3. In this case, it is sufficient that the vertices n1 to n3 overlap part of the battery cell 33 when the battery cell 33 is viewed in the left-right direction.

[0095] As described above, the resin part 32 has through holes 32b at the positions of the connection parts 44a to 44e (FIGS. 10A, 11A, and 12A). As shown in FIG. 6, when the battery cell 33 is viewed in the left-right direction, the through holes 32b are formed at the center C of the equilateral triangle T. By positioning the through holes 32b in this way, it is possible to ensure a sufficient distance between the through holes 32b and the battery cells 33.

[0096] Note that "through hole 32b is formed at the center C of equilateral triangle T" does not necessarily mean that the center of through hole 32b and the center C of equilateral triangle T are aligned. In other words, the center of through hole 32b may be offset from the center C of equilateral triangle T. In this case, it is sufficient that the center C of equilateral triangle T is located inside through hole 32b (inside large diameter portion 32b2).

[0097] The arrangement of the battery cells 33 is not limited to the example shown in Fig. 6. Fig. 14 is a diagram showing a modified layout of the battery cells 33. In this diagram, four adjacent battery cells 33 are located at vertices n1 to n4 of a square L. For example, the centers of the four battery cells 33 may be located at vertices n1 to n4 of the square L. In this case, the through-holes 32b may be formed at the center C of the square L. By setting the positions of the through-holes 32b in this way, it is possible to ensure a sufficient distance from the through-holes 32b to the battery cells 33.

[0098] Note that "the battery cells 33 are located at the vertices n1 to n4 of the square L" does not necessarily mean that the center C of the battery cells 33 and the vertices n1 to n4 are perfectly aligned. That is, the center C of the battery cells 33 may be offset from the vertices n1 to n4. In this case, it is sufficient that the vertices n1 to n4 overlap a portion of the battery cells 33 when the battery cells 33 are viewed in the left-right direction. Furthermore, "the through-holes 32b are formed at the center C of the square L" does not necessarily mean that the center of the through-holes 32b and the center C of the square L are aligned. That is, the center of the through-holes 32b may be offset from the center C of the square L. In this case, it is sufficient that the center C of the square L is located inside the through-holes 32b (inside the large-diameter portions 32b2).

[0099] [summary] (1) As described above, the battery pack 30 includes a plurality of battery cells 33 having terminals 33a at the left and right ends, and a left holder 31L. The left holder 31L includes a resin portion 32 molded from resin and a plurality of lead plates 41 held by the resin portion 32. The plurality of battery cells 33 are aligned in two directions perpendicular to the left-right direction. The plurality of lead plates 41 include a first lead plate 41 (e.g., lead plate 41B) connected to the terminal 33a of a first battery cell 33 and a second lead plate 41 (e.g., lead plate 41C) connected to the terminal 33a of another battery cell 33. The resin portion 32 has a through hole 32b formed therethrough in the left-right direction. The through hole 32b is located between the outer edges 41e of the two lead plates 41.

[0100] This battery pack 30 can simplify its manufacturing process. For example, it is possible to form the left holder 31L by insert molding using a base material 40L having multiple lead plates 41 connected to each other, and then separate the connected lead plates 41 using a punch 92 inserted into the through hole 32b. This reduces the number of press operations required to obtain the multiple lead plates 41 and the number of parts required for the press operations. Furthermore, by aligning the positions of the left holder 31L and the battery cells 33, the positions of the multiple lead plates 41 and the battery cells 33 will coincide. As a result, it is possible to easily weld the lead plates 41 of the left holder 31L to the battery cells 33.

[0101] (2) In the structure of (1), the outer edges 41e of the two lead plates 41 have portions exposed inside the through holes 32b.

[0102] (3) In the structure of (1) or (2), when the battery cells 33 are viewed in the left-right direction, three adjacent battery cells 33 may be located at the three vertices n1 to n3 of an equilateral triangle T. The through-hole 32b may be located at the center C of the equilateral triangle T. This structure makes it easy to ensure a sufficient distance between the through-hole 32b and the battery cells 33.

[0103] (4) In the structure of (1) or (2), when the battery cells 33 are viewed in the left-right direction, four adjacent battery cells 33 may be located at four vertices n1 to n4 of a square L. The center C of the square L may be located inside the through-hole 32b. This structure makes it easy to ensure a sufficient distance between the through-hole 32b and the battery cells 33.

[0104] (5) In any of the structures (1) to (4), the left holder 31L may have a signal line 42 (e.g., signal line 42D) electrically connected to the circuit board 51 and a lead plate 41 (e.g., lead plate 41C). The signal line 42 may be arranged along the outer edge 41e of the lead plate 41. The resin part 32 may have a through hole 32b formed therein, penetrating the resin part 32 in the left-right direction. The through hole 32b may be located between the signal line 42 and the outer edge 41e of the lead plate 41.

[0105] This structure enables a manufacturing method in which the left holder 31L is formed by insert molding using a base material 40L having connected signal wires 42 and lead plates 41, and then the connected lead plates 41 and signal wires 42 are separated using a punch 92 inserted into the through hole 32b. Therefore, by aligning the positions of the left holder 31L and the battery cell 33, the position of the signal wires 42 can be optimized, making it easier to assemble the battery pack 30.

[0106] (6) In the structure of (5), the signal line 42 and the outer edge 41e of the lead plate 41 have portions that are exposed inside the through hole 32b.

[0107] (7) In any of the structures (1) to (6), a recess 41g may be formed in the outer edge 41e of the lead plate 41 (e.g., lead plate 41B). The inner edge of the recess 41g may be exposed through the through-hole 32b. This structure can reduce the distance between the outer edges 41e of two adjacent lead plates 41. As a result, the area of ​​each lead plate 41 can be increased, and the electrical resistance of the lead plate 41 can be reduced.

[0108] In the structures (8) and (7), a recess 41g may be formed in the outer edge 41e of the other lead plate 41 (e.g., lead plate 41C). The inner edge of this recess 41g may be exposed through the through hole 32b. This structure further reduces the distance between the outer edges 41e of the two lead plates 41.

[0109] (9) In any of the structures (1) to (6), the outer edge 41e of one lead plate 41 (e.g., lead plate 41A) may have a protrusion 41h extending toward the outer edge 41e of the other lead plate 41 (e.g., lead plate 41B). The protrusion 41h may be exposed inside the through hole 32b.

[0110] In the structures (10) and (9), a recess 41f may be formed in the outer edge 41e of lead plate 41B. The through hole 32b may be located between the outer edge 41e of lead plate 41A and the inner edge of the recess 41f in the outer edge 41e of lead plate 41B. This structure reduces the distance between the outer edge 41e of lead plate 41B and the outer edge 41e of lead plate 41A. As a result, the area of ​​lead plates 41A and 41B can be increased, and the electrical resistance of lead plates 41A and 41B can be reduced. (11) In any of the structures (1) to (10), the battery pack 30 may have a right holder 31R disposed on the right side of the battery cell 33. The right holder 31R has a resin portion 32 molded from resin and a plurality of lead plates 41 held by the resin portion 32. The resin portion 32 of the right holder 31R also has a through hole 32b that penetrates the resin portion 32 in the left-right direction. The through hole 32b is located between the outer edges 41e of two adjacent lead plates 41.

[0111] This battery pack 30 can be manufactured by forming the right holder 31R by insert molding using a base material having multiple lead plates 41 connected to each other, and then separating the connected lead plates 41 using a punch 92 inserted into the through hole 32b. This reduces the number of press operations required to obtain the multiple lead plates 41 and the number of parts required for the press operations. Furthermore, by aligning the positions of the right holder 31R and the battery cells 33, the positions of the multiple lead plates 41 and the battery cells 33 will coincide. As a result, the welding of the lead plates 41 of the right holder 31R to the battery cells 33 can be facilitated.

[0112] (12) As described above, the manufacturing method of the battery pack 30 includes the steps of: preparing a base material 40L having a plurality of lead plates 41 and connection portions 44 (e.g., connection portions 44a) that connect the outer edges 41e of two adjacent lead plates 41 (e.g., lead plates 41B and 41C); forming a left holder 31L having a resin portion 32 that holds the base material 40L by insert molding; forming through holes 32b in the resin portion 32 at positions corresponding to the connection portions 44; and cutting the connection portions 44 using a punch 92 inserted into the through holes 32b.

[0113] This manufacturing method can reduce the number of press operations required to obtain multiple lead plates 41 and the number of parts required for the press operations. Furthermore, by aligning the left holder 31L with the battery cells 33, the positions of the multiple lead plates 41 and the battery cells 33 will match. As a result, welding the lead plates 41 of the left holder 31L to the battery cells 33 can be simplified.

[0114] (13) The manufacturing method of (12) includes a step of placing the left holder 31L on the left side of the plurality of battery cells 33 and welding the terminals 33a of the battery cells 33 to the lead plates 41.

[0115] (14) In the manufacturing method of (13), when the plurality of battery cells 33 are viewed in the left-right direction, three adjacent battery cells 33 may be located at the three vertices n1 to n3 of an equilateral triangle T. In the molding process, a through-hole 32b penetrating the resin part 32 may be formed at the center C of the equilateral triangle T. This manufacturing method makes it easy to ensure a sufficient distance between the through-hole 32b and the battery cells 33.

[0116] (15) In the manufacturing method of (13), when the plurality of battery cells 33 are viewed in the left-right direction, four adjacent battery cells 33 may be located at four vertices n1 to n4 of a square L. In insert molding, a through hole 32b penetrating the resin part 32 may be formed at the center C of the square L. This manufacturing method makes it easy to ensure a sufficient distance between the through hole 32b and the battery cell 33.

[0117] (16) In any of the manufacturing methods (12) to (15), the base material 40L may have a signal wire 42 (e.g., signal wire 42D) arranged along an outer edge 41e of the lead plate 41 (e.g., lead plate 41C), and a connection portion 44 (e.g., connection portion 44c) connecting the outer edge 41e of the lead plate 41 to the signal wire 42. In the molding step, a through hole 32b penetrating the resin portion 32 may be formed at a position corresponding to the connection portion 44. Thereafter, the connection portion 44 may be cut by a punch 92 inserted into the through hole 32b.

[0118] The battery pack and the manufacturing method thereof proposed in the present disclosure are not limited to the above-described examples.

[0119] For example, the layout of the lead plates 41 is not limited to the example shown in FIG. 7 and may be changed as appropriate.

[0120] Furthermore, the shapes of the connection portions 44 connecting the outer edges 41e of two adjacent lead plates 41 and the connection portions 44 connecting the signal wires 42 and the lead plates 41 are not limited to the examples shown in Figures 10A, 11A, and 12A. All of the connection portions 44 of the substrate 40L have a sufficient length, and only a portion of them may be cut in the cutting steps shown in S103 and S106 of Figure 8. The finally obtained holders 31R and 31L may not have the recesses 41f, 41g, and 41j shown in Figures 10A, 11A, and 12A. [Explanation of symbols]

[0121] 2: crankshaft, 2a: pedal, 5: chain, 6: rear wheel, 7: handlebars, 8: handlebar stem, 9: front wheel, 11: seat tube, 17: frame, 17a: head pipe, 18: saddle, 19: front fork, 20: drive unit, 30: battery pack, 31L: left holder, 31R: right holder, 32: resin part, 32a: recess, 32b: through hole, 32b1: small diameter part, 32b2: large diameter part, 32e: fastening hole, 33: battery cell, 33a: terminal, 33a+: positive terminal, 33a-: Negative terminal, 34: central holder, 34a: retaining hole, 40L: base material, 41, 41A to 41K: lead plate, 41a: welded portion, 41b: slit, 41e: outer edge, 41f: recess, 41g: recess, 41h: convex portion, 41i: convex portion, 41j: recess, 42, 42B to 42E, 42G to 42K: signal line, 42a: recess, 43A, 43F: power terminal, 43B to 43E: signal terminal, 44, 44a to 44e: connection portion, 51: circuit board, 91: die, 91a: recess, 92: punch, 100: electric assist bicycle.

Claims

1. a plurality of battery cells each having a terminal at a first end in a first direction; the first holder is disposed on the first side of the plurality of battery cells and includes a resin portion molded from resin and a plurality of lead plates held by the resin portion; and the plurality of battery cells includes a first battery cell and a second battery cell arranged side by side in a second direction intersecting the first direction; the plurality of lead plates include a first lead plate connected to the terminal of the first battery cell and having a first edge, and a second lead plate connected to the terminal of the second battery cell and having a second edge facing the first edge in the second direction; a through hole penetrating the resin portion in the first direction is formed in the resin portion; The through hole is located between the first edge of the first lead plate and the second edge of the second lead plate. Battery pack.

2. The first edge of the first lead plate and the second edge of the second lead plate have portions exposed inside the through hole. The battery pack according to claim 1 .

3. the plurality of battery cells further includes a third battery cell; When the plurality of battery cells are viewed in the first direction, the first battery cell, the second battery cell, and the third battery cell are located at three vertices of an equilateral triangle, respectively; When the plurality of battery cells are viewed in the first direction, the through hole is located at the center of the equilateral triangle. The battery pack according to claim 1 .

4. the plurality of battery cells further includes a third battery cell and a fourth battery cell; When the plurality of battery cells are viewed in the first direction, the first battery cell, the second battery cell, the third battery cell, and the fourth battery cell are located at four vertices of a square, respectively; When the plurality of battery cells are viewed in the first direction, the through-hole is located at the center of the square. The battery pack according to claim 1 .

5. Further comprising a circuit board; the first holder has a signal line electrically connected to the circuit board and a third lead plate; the signal line is along a third edge of the third lead plate; The resin portion has a through hole formed therein, the through hole passing through the resin portion in the first direction and positioned between the signal line and the third edge of the third lead plate. The battery pack according to claim 1 .

6. The signal line and the third edge of the third lead plate have exposed portions inside the through hole. The battery pack according to claim 5 .

7. a recess formed in the first edge of the first lead plate; The inner edge of the recess formed in the first edge is exposed inside the through hole. The battery pack according to claim 1 .

8. a recess formed on the second edge of the second lead plate; The inner edge of the recess formed in the second edge is exposed inside the through hole. The battery pack according to claim 7.

9. the first edge of the first lead plate has a protrusion extending toward the second edge of the second lead plate; The protrusion is exposed inside the through hole. The battery pack according to claim 1 .

10. a recess formed in the second edge of the second lead plate; The through hole is located between the first edge of the first lead plate and an inner edge of the recess of the second edge. The battery pack according to claim 9.

11. each of the plurality of battery cells has a terminal at an end on a second side in the first direction; the battery pack has a second holder that is disposed on the second side of the plurality of battery cells and includes a resin portion molded from resin and a plurality of lead plates held by the resin portion; the plurality of battery cells includes a fifth battery cell and a sixth battery cell, the plurality of lead plates of the second holder include a fourth lead plate and a fifth lead plate, a through hole penetrating the resin portion of the second holder in the first direction is formed in the resin portion; The through hole formed in the resin portion of the second holder is located between an edge of the fourth lead plate and an edge of the fifth lead plate. The battery pack according to claim 1 .

12. preparing a substrate having a first lead plate, a second lead plate aligned with the first lead plate, and a connecting portion connecting an edge of the first lead plate to an edge of the second lead plate; a molding step of forming a holder having a resin portion for holding the base material by insert molding, and forming a through hole in the resin portion at a position corresponding to the connection portion; a cutting step of cutting the connection portion with a punch inserted into the through hole; A method for manufacturing a battery pack having the above structure.

13. providing a plurality of battery cells including a first battery cell and a second battery cell, each having a terminal at an end on a first side in a first direction; The holder is placed on the first side of the plurality of battery cells, and a terminal of the first battery cell is welded to the first lead plate, and a terminal of the second battery cell is welded to the second lead plate. The method for manufacturing a battery pack according to claim 12.

14. the plurality of battery cells further includes a third battery cell; When the plurality of battery cells are viewed in the first direction, the first battery cell, the second battery cell, and the third battery cell are arranged at three vertices of an equilateral triangle, respectively; In the molding step, the through hole is formed at the center of the equilateral triangle. The method for manufacturing the battery pack according to claim 13 .

15. the plurality of battery cells further includes a third battery cell and a fourth battery cell; When the plurality of battery cells are viewed in the first direction, the first battery cell, the second battery cell, the third battery cell, and the fourth battery cell are arranged at four vertices of a square, respectively; In the molding step, the through hole is formed in the center of the square. A method for manufacturing a battery pack according to claim 13.

16. the base material has a third lead plate, a signal line disposed along an edge of the third lead plate, and a connection portion connecting the edge of the third lead plate and the signal line, In the molding step, a through hole is formed through the resin portion at a position corresponding to the connection portion, In the cutting step, the connection portion is cut by a punch inserted into the through hole. The method for manufacturing a battery pack according to claim 12.

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