Battery pack and method for manufacturing a 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 Art

[0002] An electric vehicle (including an electric four-wheel vehicle, an electric two-wheel vehicle, and an electric assist bicycle) is equipped with a battery pack composed of a plurality of battery cells. For example, in Patent Documents 1 and 2 below, a battery pack having a plurality of cylindrical battery cells is disclosed. The battery pack has a plurality of lead plates for connecting the terminals of the plurality of battery cells.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the manufacturing process of a battery pack, generally, the positions of a plurality of lead plates are aligned with a plurality of battery cells, and the terminals of the battery cells and the lead plates are welded. However, the positions of the battery cells and the lead plates may be misaligned, and the welding operation may not be performed smoothly. In particular, when the number of battery cells and the number of lead plates increase, the alignment operation becomes complicated.

Means for Solving the Problems

[0005] (1) The battery pack proposed in this disclosure comprises a plurality of battery cells, each having a terminal at its end on a first side in a first direction; a first holder comprising 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 through holes formed therein that penetrate the resin portion in the first direction. The through holes are located between the first edge of the first lead plate and the second edge of the second lead plate.

[0006] This battery pack simplifies the manufacturing process. For example, by using a base material with multiple interconnected lead plates, a first holder can be formed by insert molding, and then the interconnected lead plates can be separated by a punch inserted into a through-hole. This 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 positions of the first holder and the battery cells, the positions of the multiple lead plates and the battery cells can be aligned. As a result, the welding process between the lead plates and battery cells 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 portions that are exposed inside the through hole.

[0008] (3) In the battery pack of (1) or (2), the plurality of battery cells 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 located at the three vertices of an equilateral triangle, respectively. Also, 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 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 located at the four vertices of a square, respectively. 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 cell.

[0010] (5) In any of the battery packs 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 the third edge of the third lead plate. The resin part may have a through hole that penetrates the resin part in the first direction and is located between the signal line and the third edge of the third lead plate.

[0011] This structure allows for a manufacturing method in which a left holder is formed by insert molding using a base material that has interconnected signal wires and lead plates, and then the lead plates and signal wires are separated by a punch inserted into a through hole. Therefore, by aligning the position of the first holder and the battery cell, the position of the signal wires can be optimized, thus simplifying the assembly of the battery pack.

[0012] In the battery pack of (6)(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 any of the battery packs of (1) to (6), a recess is 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 makes it possible to 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] In the battery pack of (8)(7), a recess is 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. This structure allows for an even smaller distance between the edges of two adjacent lead plates.

[0015] (9) In any of the battery packs 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. The protrusion may be exposed inside the through hole.

[0016] In the battery pack of (10)(9), a recess is formed on the second edge of the second lead plate, and the through hole may be located between the first edge of the first lead plate and the inner edge of the recess on the second edge. This structure allows the distance between the edge of the first lead plate and the edge of the second lead plate to be reduced. 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 any of the battery packs of (1) to (10), each of the plurality of battery cells may have a terminal at the end on the second side in the first direction. The battery pack may have a second holder which is located on the second side of the plurality of battery cells and includes a resin portion which is molded from resin and a plurality of lead plates which are 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 has a through hole which penetrates the resin portion in the first direction, and the through hole formed in the resin portion of the second holder may be located between the edge of the fourth lead plate and the edge of the fifth lead plate.

[0018] (12) A method for manufacturing a battery pack proposed in this disclosure includes the steps of: preparing a base material having a first lead plate, a second lead plate adjacent to the first lead, and a connecting portion connecting the edge of the first lead plate and the edge of the second lead plate; 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 connecting portion; and cutting the connecting 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 the battery cells, the positions of the multiple lead plates and the battery cells can be matched. As a result, the welding process between the lead plates and battery cells can be simplified.

[0020] The manufacturing method of (13)(12) may include the steps of preparing a plurality of battery cells, each comprising a first battery cell and a second battery cell, each having terminals at the end on the first side in a first direction, and arranging the holder on the first side of the plurality of battery cells, welding the terminals of the first battery cell to the first lead plate, and welding the terminals 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 viewing the plurality of battery cells in the first direction, the first battery cell, the second battery cell, and the third battery cell are respectively arranged at three vertices of an equilateral triangle, and in the forming step, the through hole may be formed at the center of the equilateral triangle. According to this manufacturing method, it is easy to ensure a sufficient distance between the through hole and the battery cells.

[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 viewing the plurality of battery cells in the first direction, the first battery cell, the second battery cell, the third battery cell, and the fourth battery cell may be respectively arranged at four vertices of a square. In the forming step, the through hole may be formed at the center of the square. According to this manufacturing method, it is easy to ensure a sufficient distance between the through hole and the battery cells.

[0023] (16) In any of the manufacturing methods of (12) to (15), the base material may have a third lead plate, a signal line arranged along the edge of the third lead plate, and a connection portion connecting the edge of the third lead plate and the signal line. In the forming step, a through hole penetrating the resin portion may be formed at a position corresponding to the connection portion, and in the cutting step, the connection portion may be cut by a punch inserted into the through hole. According to this method, if the positions of the holder and the battery cells are aligned, the position of the signal line can be optimized, so that the assembly work of the battery pack can be facilitated.

Brief Description of the Drawings

[0024] [Figure 1] It is a side view of an electric bicycle equipped with the battery pack proposed in the present disclosure. [Figure 2] It is a perspective view showing an example of the battery pack. [Figure 3] It is an exploded perspective view of the battery pack. [Figure 4A] It is a perspective view of the left holder constituting the battery pack. [Figure 4B] This is a perspective view showing the inside (battery cell side) of the left holder. [Figure 5] This is an exploded perspective view showing the lead plates and battery cells in the left holder, and the lead plates in the right holder. [Figure 6] This diagram shows the positional relationship between the battery cell, the through-hole formed in the resin part, and the welded part. [Figure 7] This diagram illustrates the electrical connections between the lead plates of the left holder, the battery cell, and the lead plates of the right holder. [Figure 8] This is a flowchart illustrating the manufacturing method of a battery pack. [Figure 9A] This figure shows an example of a substrate used in the manufacturing process of a battery pack. In this figure, two adjacent lead plates are connected to each other, and adjacent lead plates and signal lines are also connected to each other. [Figure 9B] This figure shows the lead plate and signal lines separated, as shown in Figure 9A. [Figure 10A] This is an enlarged view of region X shown in Figure 9A. [Figure 10B] This is an enlarged view of region X shown in Figure 9B. Region X in Figure 9B is the same as region X in Figure 9A. [Figure 11A] This is an enlarged view of region XI shown in Figure 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] This is an enlarged view of region XII shown in Figure 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] This diagram illustrates the process of cutting the connection point, and is a cross-sectional view of the left holder along the line XIII-XIII shown in Figure 10A. [Figure 14] This figure shows a modified example of the battery cell layout. [Modes for carrying out the invention]

[0025] The battery pack and method for manufacturing the battery pack proposed in this disclosure will be described below. Figure 1 is a side view of an electric assist bicycle 100, which is an example of a vehicle having 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, the bicycle 100 has a crank axle 2. A crank arm is attached to the end of the crank axle 2. A pedal 2a is connected to the end of this crank arm. The crank axle 2 is supported at the lower end of the seat tube 11. A saddle 18 is fixed to the upper end of the seat tube 11.

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

[0028] As shown in Figure 1, the bicycle 100 has a drive unit 20. The drive unit 20 has an electric motor that outputs a force (auxiliary torque) to assist in driving the rear wheel 6, and a reduction gear. The electric motor is powered by electricity supplied from a battery pack 30. In the example of bicycle 100, the battery pack 30 is attached to the rear of the seat tube 11, and the drive unit 20 is located behind the crank axle 2. The layout of the drive unit 20 and the battery pack 30 is not limited to the example of bicycle 100 and may be changed as appropriate.

[0029] The force applied to the crank axle 2 through the pedal 2a is transmitted to the rear wheel 6 via, for example, the 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] Figures 2 to 8 show an example of a battery pack 30 proposed in this disclosure. In these figures, the directions indicated by Z1 and Z2 are referred to as upward and downward, respectively. 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 explain the relative positions and shapes of the components, members, and elements that constitute 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 such that the backward direction (Y2 direction) shown in Figure 2 faces upward on the bicycle 100.

[0031] As shown in Figure 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 central holder 34 and a circuit board 51. The battery pack 30 may also have a housing (not shown) that accommodates the battery cells 33 and holders 31L and 31R.

[0032] [Battery cell] As shown in Figure 3, each battery cell 33 has terminals 33a at its left and right ends. Some 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. Multiple battery cells 33 are arranged in two directions perpendicular to the left-right direction. More specifically, multiple battery cells 33 are arranged in the front-back direction (Y1-Y2 direction) and in an oblique direction inclined in the front-back direction and the up-down direction (Z1-Z2 direction).

[0033] [Central holder] As shown in Figure 3, the central holder 34 has multiple holding holes 34a that penetrate it in the left-right direction. Multiple battery cells 33 may be held by fitting each of the multiple holding holes 34a. Unlike the example shown in the figure, the battery pack 30 does not have 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] The left holder 31L is positioned to the left of the multiple battery cells 33. As shown in Figures 4A and 5, the left holder 31L has a resin part 32 and multiple lead plates 41A to 41F.

[0035] Each lead plate 41A to 41F has multiple welds 41a. As shown in Figure 5, for example, each lead plate 41A and 41F may have three welds 41a, and each lead plate 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 Figure 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 Figure 6, the slit 41b is, for example, an approximately H shape rotated 90 degrees, but its shape is not limited to this, and may be, for example, an I shape.

[0036] As shown in Figure 4B, a plurality of recesses 32a may be formed on the right side of the resin part 32 (the side facing the battery cell 33). The left sides of the plurality of battery cells 33 may be fitted into these plurality of recesses 32a, respectively.

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

[0038] In insert molding, lead plates 41A to 41F (specifically, the base material 40L described later) are placed in the cavity of the mold, and then molten resin (material for the resin part 32) is filled into this cavity. As the material for the resin part 32, for example, polycarbonate (PC), ABS resin (Acrylonitrile Butadiene Styrene resin), a mixed resin of PC and ABS, polypropylene (PP), polyamide (PA), polyphenylene sulfide (PPS), etc. are available. The resin part 32 is formed when the molten resin solidifies, and the lead plates 41A to 41F are fixed to the resin part 32. Fasteners such as screws or bolts do not need to be used to fix the lead plates 41A to 41F to the resin part 32.

[0039] As shown in Figure 7(a), the multiple lead plates 41A to 41F are arranged along a common plane and do not overlap when viewed from left to right. The left holder 31L has, for example, six lead plates 41A to 41F. In one example of the battery pack 30, lead plate 41A is located at the very front. 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. Also, 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 to 41F are not limited to the example described here. They may be changed as appropriate according to the number, layout, and connection relationships of the battery cells 33.

[0040] As shown in Figure 4A, the left holder 31L may have power terminals 43A and 43F. Power terminals 43A and 43F protrude to the outside of 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 and 43F. As shown in Figure 7(a), power terminal 43A may be formed on, for example, the lead plate 41A. Also, power terminal 43F may be formed on, for example, the lead plate 41F.

[0041] As shown in Figure 4A, the left holder 31L may further have signal terminals 43B to 43E. The signal terminals 43B to 43E also protrude to the outside of the resin part 32. As shown in Figure 7(a), the left holder 31L may have multiple signal lines 42B, 42D, and 42E. The signal lines 42B, 42D, and 42E extend from lead plates 41B, 41D, and 41E, respectively. Signal terminal 43B may be formed at the end of signal line 42B. Similarly, signal terminal 43D may be formed at the end of signal line 42D, and signal terminal 43E may be formed at the end of signal line 42E. Signal terminal 43C may extend from lead plate 41C. Terminals 43A to 43F are located at the front of the battery pack 30 and may be arranged in the front-to-back direction.

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

[0043] In the following explanations where lead plates 41A to 41F are not distinguished, the designation "41" will be used for the lead plates. Similarly, in explanations where signal lines 42B to 42E are not distinguished, the designation "42" will be used for the signal lines, and in explanations where power terminals 43A and 43F and signal terminals 43B to 43E are not distinguished, the designation "43" will be used for these terminals.

[0044] As will be explained in detail later, in insert molding, the outer edges 41e of two adjacent lead plates 41 (for example, lead plates 41A and 41B) are interconnected by connecting portions 44a, 44b, and 44e (see Figures 9A, 10A, and 11A). Therefore, the multiple lead plates constitute a single metal plate (hereinafter referred to as "base material 40L," see Figure 9A). The signal lines 42 also constitute the base material 40L together with the lead plates 41. After the base material 40L is fixed to the resin part 32 by insert molding, the connecting portions 44a, 44b, and 44e are cut by press working, and the multiple lead plates 41 are separated (cutting process, see Figure 9B). To enable such press working, the resin part 32 has through holes 32b (see Figure 4A) that penetrate 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 process, the connecting parts 44a, 44b, and 44e are cut by a punch inserted into the through-hole 32b.

[0045] Furthermore, the base material 40L (Figure 9A), which serves as the basis for the multiple lead plates 41, utilizes multiple types of connection parts 44a to 44e (see Figures 9A, 10A, 11A, and 12A). In the following, when these types are not distinguished, the designation "44" will be used for the connection part.

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

[0047] Furthermore, multiple recesses 32a (see Figure 3) may be formed on the left side of the resin part 32 (the side facing the battery cell 33). The right sides of the multiple battery cells 33 may be fitted into these multiple recesses 32a, respectively.

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

[0049] As shown in Figure 2, signal terminals 43G to 43K are connected to the circuit board 51. A control IC chip mounted on the circuit board 51 may detect the voltage of signal terminals 43G to 43K and monitor the battery cell 33 (more specifically, the battery cell 33 welded to lead plates 41G to 41K to which terminals 43G to 43K are connected via signal lines) based on that voltage.

[0050] In the following explanations where lead plates 41G to 41K are not distinguished, the designation "41" will be used for the lead plates. Similarly, in explanations where signal lines 42G to 42K are not distinguished, the designation "42" will be used for the signal lines, and in explanations where signal terminals 43G to 43K are not distinguished, the designation "43" will be used for these terminals.

[0051] Similar to the lead plates 41 of the left holder 31L, in insert molding, the multiple lead plates 41 of the right holder 31R are connected to each other by connecting parts 44, forming a single metal plate (hereinafter referred to as the "base material"). The signal lines 42 extending from the lead plates 41 also constitute the base material together with the lead plates 41. After the base material is fixed to the resin part 32 by insert molding, the connecting parts 44 are cut by press working, and the multiple lead plates 41 are separated (cutting process). To enable such press working, the resin part 32 has through holes 32b (see Figure 3) that penetrate it in the left-right direction. Each through hole 32b is formed at the position of the connecting part 44. During press working, a punch is inserted into these through holes 32b, and the connecting parts 44 are cut.

[0052] [Connecting multiple battery cells] In the battery pack 30, multiple battery cells 33 connected in parallel form a set. Multiple sets are then connected in series. For example, in the battery pack 30, three battery cells 33 connected in parallel form a set. Ten such sets are then connected in series.

[0053] The electrical connections of the battery cell 33 will be explained 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 subscripts of the battery cells 33 to which the welds 41a of the lead plates 41 are welded are indicated at the positions of the welds 41a on the lead plates 41. For example, the symbol "33_1(+)" shown in Figure 7(a) indicates that the weld 41a at the position of this symbol 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 the position of this symbol is welded to the negative terminal 33a- of the second set of battery cells 33. Furthermore, in Figure 7(b), the symbol "33_1(-)" means that the weld 41a at the position of this symbol is welded to the negative terminal 33a- of the first set of battery cells 33.

[0055] As shown in Figure 7(a), the power terminal 43A (positive terminal of the battery pack 30) of the battery pack 30 is formed on lead plate 41A. The power terminal 43F (negative terminal of the battery pack 30) is formed on lead plate 41F. Between lead plate 41A and 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 cell 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 of right holder 31R (13) Lead plate 41I, (14) Lead plate 41D of left holder 31L, (15) Lead plate 41J of right holder 31R, (16) Lead plate 41E of left holder 31L, (17) Lead plate 41E of left holder 31L, (19) Lead plate 41K of right holder 31R, (21) Lead plate 41F of left holder 31L, (22) Lead plate 41F of left holder 31L, (23) 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 each welded. The lead plate 41F has three welds 41a to which the negative terminals 33a- of the three battery cells 33 are each welded. In contrast, each lead plate 41B to 41E has six welds 41a. Three of these 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 lead plate 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 each welded, and three welds 41a to which the negative terminals 33a- of the three battery cells 33 are each welded.

[0058] Furthermore, the number of battery cells 33 constituting each group is not limited to three; it may be two or more than three. Also, the number of groups connected in series may be less than 10 or more than 10.

[0059] [Battery pack manufacturing method] The manufacturing method of the battery pack 30 will be explained with reference to Figure 8.

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

[0061] Figure 9A shows 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 reduces the number of press working steps required to obtain multiple lead plates 41 and the number of parts required for press working. Figure 9B shows the lead plates 41 and signal lines 42 separated by press working (cutting step S103) performed after insert molding.

[0062] [Connection point between the two lead plates] Figures 10A and 11A are enlarged views of regions X and XI in Figure 9A, respectively. As shown in Figure 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 toward the outer edge 41e of the other lead plate 41C along a plane parallel to the base material 40L.

[0063] Furthermore, as shown in Figure 11A, the outer edge 41e of lead plate 41A and the outer edge 41e of 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 base material 40L. A recess 41f is formed in the outer edge 41e of lead plate 41B. This recess 41f will be described later.

[0064] The outer edges 41e of lead plate 41C and the outer edges 41e of lead plate 41D are also connected to each other. Similarly, the outer edges 41e of lead plate 41D and the outer edges 41e of lead plate 41E are also connected to each other, and the outer edges 41e of lead plate 41E and the outer edges 41e of lead plate 41F are also connected to each other.

[0065] Two adjacent lead plates 41 may be connected to each other by a plurality of connecting parts 44. This can increase the strength of the base material 40L. For example, lead plate 41A and lead plate 41B are connected to each other by two connecting parts 44b. Also, lead plate 41B and lead plate 41C are connected to each other by two connecting parts 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 base material 40L to be used in the manufacture of a battery pack 30 with a large number of lead plates 41.

[0067] [Connection point between signal wire and lead plate] As described above, the left holder 31L has signal lines 42 extending from each lead plate 41. The signal lines 42 may be positioned 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 suppress displacement of the signal lines 42 within the mold cavity when performing insert molding (S102), which will be described later.

[0068] For example, as shown in Figure 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 connector 44c. The connector 44c, like the connector 44a described above, is a portion that extends along a plane parallel to the base material 40L.

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

[0070] [Connection point between two signal lines] Multiple signal lines 42 may be arranged between the outer edges 41e of two lead plates 41. In this case, these multiple signal lines 42 may be connected to each other via a connector 44. In the example shown in Figure 12A, two signal lines 42D and 42E are arranged between the outer edge 41e of lead plate 41F and the outer edge 41e of lead plate 41C. The two signal lines 42D and 42E are connected to each other by a connector 44d (see Figures 9A and 12A). This structure makes it possible to suppress misalignment of each signal line 42, even when there are many signal lines 42.

[0071] Unlike the example in Figure 12A, the signal line 42 placed between the two lead plates 41 may be just one. In this case, this single signal line 42 may be connected to only one of the two lead plates 41, or to both.

[0072] [Insert molding] The left holder 31L is formed by insert molding using the base material 40L (S102). That is, after placing the base material 40L in the cavity of the mold, molten resin (material for the resin part 32) is filled into this cavity to obtain the resin part 32 that holds the base material 40L. At this time, through holes 32b are formed at positions corresponding to the multiple connection parts 44, penetrating the resin part 32 in the left-right direction. The connection parts 44 are exposed on the right and left sides of the left holder 31L through these through holes 32b. In addition, multiple fastening holes 32e (see Figure 4A) penetrating the resin part 32 may be formed in step S102.

[0073] [Cutting process] Next, the connecting portion 44 is cut by press working (more specifically, by punching holes), separating the multiple lead plates 41 and signal lines 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 obtained along the line XIII-XIII in Figure 10A.

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

[0075] Furthermore, 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 of the through hole 32b (see Figure 13(c)) is located between the outer edges 41e of two adjacent lead plates 41. The outer edges 41e of one lead plate 41 and the outer edges 41e of the other lead plate 41 have portions that are exposed inside the through hole 32b of the resin portion 32 (see Figure 13(c)).

[0076] In addition, during the cutting process in S103, multiple connecting parts 44 may be cut simultaneously. That is, multiple connecting parts 44 may be cut by a single press.

[0077] Furthermore, the connection portion 44 connecting the signal line 42 and the lead plate 41 is cut using the same procedure as in the example shown in Figure 13. As a result, multiple through holes 32b, which are aligned along the outer edge 41e of the lead plate 41, are formed between the signal line 42 and the outer edge 41e of the lead plate 41. That is, the center C1 of each through hole 32b (see Figure 13(c)) is located between the signal line 42 and the outer edge 41e of the lead plate 41. In addition, the signal line 42 and the outer edge 41e of the lead plate 41 have portions that are 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 base material containing multiple lead plates 41 and multiple signal lines 42 for the right holder 31R is prepared (S104). In this base material as well, the outer edges 41e of two adjacent lead plates 41 may be connected to each other. The signal lines 42 may also be connected to the outer edges 41e of the lead plates 41. Furthermore, two adjacent signal lines 42 may also 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 are formed in the resin part 32 in the left-right direction at positions corresponding to the multiple connection parts 44. In addition, multiple fastening holes 32e (see Figure 3) may be formed in the resin part 32 during the molding in S105.

[0080] Next, the connecting portion 44 is cut by press working (more specifically, by punching holes), separating the lead plate 41 and signal line 42 that were connected to each other (S106). In the cutting process of S106, multiple connecting portions 44 may be cut simultaneously. That is, multiple connecting portions 44 may be cut by a single press.

[0081] [Assembly process] Next, multiple battery cells 33 are fitted into the multiple holding holes 34a (see Figure 3) formed in the central holder 34 (S107). Then, the battery cells 33, the left holder 31L, and the right holder 31R are combined 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 fix the holders 31L and 31R together. Note that the combination process is not limited to the procedure described above. For example, multiple battery cells 33 may be fitted into the left holder 31L (or right holder 31R), then the central holder 34 may be fitted into the multiple battery cells 33, and then the right holder 31R (or left holder 31L) may be combined.

[0082] [Welding Process] Subsequently, 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). This completes the battery pack 30.

[0083] Furthermore, in S109, if 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 coincide with the positions of the battery cell 33. Similarly, if 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 coincide with the positions of the battery cell 33. This makes welding easier.

[0084] [Details of the connection] The following sections will provide a detailed explanation of the connection points 44 between two adjacent lead plates 41, and the connection points 44 between a lead plate 41 and a signal line 42.

[0085] As shown in Figure 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, for example, the diameter of the through hole 32b (more specifically, the diameter of the small diameter portion 32b1). If the length of the connecting portion 44a is as shown, the entire connecting portion 44a may be cut off as a result of the cutting process shown in S103-S106 in Figure 8, as shown in Figure 10B.

[0086] Furthermore, as a result of this cutting process, a recess 41g (see Figure 10B) may be formed on the outer edge 41e of one lead plate 41 and the outer edge 41e of the other lead plate 41. By utilizing such a connection portion 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 plates 41 can be increased, and the electrical resistance of the lead plates 41 can be reduced. In the final battery pack 30, the inner edge of this recess 41g will be exposed inside the through hole 32b formed in the resin portion 32.

[0087] Furthermore, as shown in Figure 11A, a recess 41f may be formed on the outer edge 41e of one lead plate 41 (41B). The connecting 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. In this structure as well, the distance between the outer edges 41e of two adjacent lead plates 41 can be reduced. Also, the length of the connecting portion 44b can be sufficiently secured. And because the distance between the two outer edges 41e is small, 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 Figure 11A, as a result of the cutting process shown in S103-S106 of Figure 8, only a portion of the connecting portion 44b may be cut, as shown in Figure 11B. Then, a portion of the connecting portion 44b (protrusion 41h) may remain on the outer edge 41e of one lead plate 41 (41A). Similarly, a portion of the connecting portion 44b (protrusion 41i) may 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 of the through hole 32b (Figure 13(c)) 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 final battery pack 30, these protrusions 41h and 41i will be exposed inside the through-hole 32b formed in the resin part 32.

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

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

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

[0092] Furthermore, as a result of this cutting process, a recess 41j (see Figure 12B) may be formed on the outer edge 41e of the lead plate 41, and a recess 42a (see Figure 12B) may be formed on the edge of the signal line 42. With this structure, the distance between the outer edge 41e of the lead plate 41 and the signal line 42 is reduced. As a result, the area of ​​the lead plate 41 can be increased, and the thickness of the signal line 42 can also be increased, thereby reducing their electrical resistance. This connection structure may be applied to other connection structures between signal lines and lead plates (for example, the connection structure between signal line 42E and lead plate 41F).

[0093] [Location of through-hole] Multiple battery cells 33 arranged in the front-to-back direction constitute multiple rows. As shown in Figure 5, the multiple battery cells 33 constitute the first row S1, the second row S2, the third row S3, and the fourth row S4. The positions of the battery cells 33 arranged in two adjacent rows are offset in the front-to-back direction. As a result, as shown in Figure 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 three battery cells 33 may be located at the vertices n1 to n3 of the equilateral triangle T. This arrangement of battery cells 33 allows for an increase in the arrangement density of battery cells 33, and enables miniaturization of the battery pack 30.

[0094] It should be noted that "the battery cell 33 is located at vertices n1 to n3 of the equilateral triangle T" does not necessarily mean that the position of the center C of the battery cell 33 and the positions of vertices n1 to n3 are perfectly coincide. In other words, the position of the center C of the battery cell 33 may be offset from the positions of vertices n1 to n3. In this case, when viewing the battery cell 33 from left to right, it is sufficient that vertices n1 to n3 overlap with a part of the battery cell 33.

[0095] As described above, the resin portion 32 has through holes 32b at the positions of the connection portions 44a to 44e (Figures 10A, 11A, and 12A). As shown in Figure 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 setting the position of the through holes 32b in this way, it is possible to secure a sufficient distance between the through holes 32b and the battery cell 33.

[0096] Furthermore, the statement that "the through-hole 32b is formed at the center C of the equilateral triangle T" does not necessarily mean that the center of the through-hole 32b and the center C of the equilateral triangle T coincide. In other words, the center of the through-hole 32b may be offset from the center C of the equilateral triangle T. In this case, the center C of the equilateral triangle T only needs to be located inside the through-hole 32b (inside the large-diameter portion 32b2).

[0097] Note that the arrangement of the battery cells 33 is not limited to the example shown in Figure 6. Figure 14 shows a modified example of the layout of the battery cells 33. In this figure, four adjacent battery cells 33 are located at vertices n1 to n4 of the 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-hole 32b may be formed at the center C of the square L. By setting the position of the through-hole 32b in this way, it is possible to secure the distance from the through-hole 32b to the battery cell 33.

[0098] Furthermore, the statement that "the battery cell 33 is located at vertices n1 to n4 of the square L" does not necessarily mean that the position of the center C of the battery cell 33 and the positions of vertices n1 to n4 are perfectly coincidental. In other words, the position of the center C of the battery cell 33 may be offset from the positions of vertices n1 to n4. In this case, when the battery cell 33 is viewed in the left-right direction, it is sufficient that vertices n1 to n4 overlap with a part of the battery cell 33. Also, the statement that "the through hole 32b is formed at the center C of the square L" does not necessarily mean that the center of the through hole 32b and the center C of the square L are coincidentally located. In other words, the center of the through hole 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 hole 32b (inside the large diameter portion 32b2).

[0099] [summary] (1) As described above, the battery pack 30 has a plurality of battery cells 33 having terminals 33a at the left and right ends, and a left holder 31L. The left holder 31L has a resin part 32 molded from resin and a plurality of lead plates 41 held by the resin part 32. The plurality of battery cells 33 are arranged 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 the 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 part 32 has a through hole 32b that penetrates the resin part 32 in the left-right direction. The through hole 32b is located between the outer edges 41e of these two lead plates 41.

[0100] This battery pack 30 simplifies the manufacturing process. For example, it is possible to form a 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 a 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 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, the welding work between the lead plates 41 of the left holder 31L and the battery cells 33 can be simplified.

[0101] (2) In the structure of (1), the outer edges 41e of the two lead plates 41 have portions that are exposed inside the through hole 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 the equilateral triangle T, respectively. The through hole 32b may be located at the center C of the equilateral triangle T. This structure makes it easy to secure a sufficient distance between the through hole 32b and the battery cell 33.

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

[0104] (5) In any of the structures of (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 that penetrates 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 allows for a manufacturing method in which a base material 40L having interconnected signal wires 42 and lead plates 41 is used to form the left holder 31L by insert molding, and then the interconnected lead plates 41 and signal wires 42 are separated by a punch 92 inserted into a through hole 32b. Therefore, by aligning the left holder 31L with the battery cell 33, the position of the signal wires 42 can be optimized, making the assembly of the battery pack 30 easier.

[0106] In the structure of (6)(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 of (1) to (6), a recess 41g may be formed on the outer edge 41e of the lead plate 41 (for example, lead plate 41B). The inner edge of the recess 41g may be exposed by the through hole 32b. This structure makes it possible to 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 plates 41 can be reduced.

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

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

[0110] In the structure of (10)(9), a recess 41f may be formed in the outer edge 41e of the lead plate 41B. The through hole 32b may be located between the outer edge 41e of the lead plate 41A and the inner edge of the recess 41f of the outer edge 41e of the lead plate 41B. This structure makes it possible to reduce the distance between the outer edge 41e of the lead plate 41B and the outer edge 41e of the lead plate 41A. As a result, the area of ​​the lead plates 41A and 41B can be increased, and the electrical resistance of the lead plates 41A and 41B can be reduced. In any of the structures described in (11)(1) to (10), the battery pack 30 may have a right holder 31R positioned to the right 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 allows for a manufacturing method in which a right holder 31R is formed by insert molding using a base material having multiple lead plates 41 connected to each other, and then the connected lead plates 41 are separated by a punch 92 inserted into a 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 press operations. Furthermore, by aligning the positions of the right holder 31R and the battery cell 33, the positions of the multiple lead plates 41 and the positions of the battery cell 33 coincide. As a result, the welding work between the lead plates 41 of the right holder 31R and the battery cell 33 can be simplified.

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

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

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

[0115] In the manufacturing method of (14)(13), when multiple 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 that penetrates the resin part 32 may be formed at the center C of the equilateral triangle T. This manufacturing method makes it easy to secure a sufficient distance between the through hole 32b and the battery cell 33.

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

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

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

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

[0120] Furthermore, the shape of the connecting portion 44 that connects the outer edges 41e of two adjacent lead plates 41, and the shape of the connecting portion 44 that connects the signal line 42 to the lead plate 41, are not limited to the examples shown in Figures 10A, 11A, and 12A. The connecting portions 44 of the base material 40L are all of sufficient length, and in the cutting process shown in S103 and S106 of Figure 8, only a portion thereof may be cut. In the final holders 31R and 31L, the recesses 41f, 41g, and 41j shown in Figures 10A, 11A, and 12A do not need to be formed. [Explanation of Symbols]

[0121] 2: Crank axle, 2a: Pedal, 5: Chain, 6: Rear wheel, 7: Handlebars, 8: Handlebar stem, 9: Front wheel, 11: Seat tube, 17: Frame, 17a: Head tube, 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-: 41: Negative terminal, 34: Central holder, 34a: Holding hole, 40L: Base material, 41·41A~41K: Lead plate, 41a: Welded part, 41b: Slit, 41e: Outer edge, 41f: Recess, 41g: Recess, 41h: Protrusion, 41i: Protrusion, 41j: Recess, 42·42B~42E·42G~42K: Signal line, 42a: Recess, 43A·43F: Power terminal, 43B~43E: Signal terminal, 44·44a~44e: Connection part, 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 the end on the first side in the first direction, The first holder is located 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. 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 having a welded portion and a first edge welded to the terminals of the first battery cell, and a second lead plate having a welded portion welded to the terminals of the second battery cell and a second edge facing the first edge in the second direction. The first lead plate and the second lead plate have portions embedded in the resin portion, in addition to the welded portion. The resin portion has a through hole formed in it that penetrates the resin portion 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. Battery pack.

2. The first edge of the first lead plate and the second edge of the second lead plate have portions that are exposed inside the through hole. The battery pack described in claim 1.

3. The plurality of battery cells 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 are located at the three vertices of an equilateral triangle, 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 described in claim 1.

4. The plurality of battery cells 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 are located at the four vertices of the square, 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 described in claim 1.

5. It further comprises a circuit board, The first holder has signal lines electrically connected to the circuit board and a third lead plate. The signal line is along the third edge of the third lead plate, The resin portion has a through hole that penetrates the resin portion in the first direction and is located between the signal line and the third edge of the third lead plate. The battery pack described in claim 1.

6. The signal line and the third edge of the third lead plate have portions that are exposed inside the through hole. The battery pack described in claim 5.

7. A recess is formed on the first edge of the first lead plate. The inner edge of the recess formed on the first edge is exposed on the inside of the through hole. The battery pack described in claim 1.

8. A recess is formed on the second edge of the second lead plate. The inner edge of the recess formed on the second edge is exposed on the inside of the through hole. The battery pack described in claim 7.

9. The first edge of the first lead plate has a protrusion that extends toward the second edge of the second lead plate. The aforementioned protrusion is exposed on the inside of the through hole. The battery pack described in claim 1.

10. A recess is formed on the second edge of the second lead plate. The through hole is located between the first edge of the first lead plate and the inner edge of the recess of the second edge. The battery pack described in claim 9.

11. Each of the plurality of battery cells has a terminal at the end on the second side in the first direction, The battery pack has a second holder which is located 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 include 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, The resin portion of the second holder has a through hole that penetrates the resin portion in the first direction. The through hole formed in the resin portion of the second holder is located between the edge of the fourth lead plate and the edge of the fifth lead plate. The battery pack described in claim 1.

12. A plurality of battery cells, each having a terminal at the end on the first side in the first direction, The first holder is located 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. 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 having a welded portion and a first edge welded to the terminals of the first battery cell, and a second lead plate having a welded portion welded to the terminals of the second battery cell and a second edge facing the first edge in the second direction. The first lead plate and the second lead plate have portions embedded in the resin portion, in addition to the welded portion. The resin portion has a through hole formed in it that penetrates the resin portion 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. The first edge of the first lead plate and the second edge of the second lead plate have exposed portions that are exposed inside the through hole. A method for manufacturing a battery pack, A step of preparing a substrate having a first lead plate, a second lead plate, and a connecting portion connecting the first edge of the first lead plate and the second edge of the second lead plate, A molding step is to form a first holder that holds the substrate and has the resin portion by insert molding, wherein the portion of the first lead plate and the portion of the second lead plate are embedded in the resin portion, and the through hole is formed at a position in the resin portion corresponding to the connecting portion, A cutting step in which the connecting portion is cut by a punch inserted into the through hole, A welding step comprising welding the welded portion of the first lead plate to the terminal of the first battery cell, and welding the welded portion of the second lead plate to the terminal of the second battery cell. A method for manufacturing a battery pack having the following characteristics.

13. The plurality of battery cells further include a third battery cell, When viewing the plurality of battery cells in the first direction, the first battery cell, the second battery cell, and the third battery cell are arranged at the three vertices of an equilateral triangle, In the molding process, the through hole is formed at the center of the equilateral triangle. A method for manufacturing a battery pack according to claim 12.

14. The plurality of battery cells 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 are arranged at the four vertices of the square, In the molding process, the through hole is formed in the center of the square. A method for manufacturing a battery pack as described in claim 12.

15. The substrate has a third lead plate, a signal line arranged along the edge of the third lead plate, and a connecting portion that connects the edge of the third lead plate and the signal line. In the molding process, a through hole is formed at a position corresponding to the connecting portion, which penetrates the resin portion. In the cutting process, the connecting portion is cut by a punch inserted into the through hole. A method for manufacturing a battery pack according to claim 12.

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