Battery pack

Abstract

To improve an energy density of a battery pack by reducing the size of the battery pack.SOLUTION: A battery pack 10 comprises an assembled battery 30, a lower case 21, an upper case 22, and a bus bar module 40. The bus bar module 40 comprises an outer connection positive electrode terminal 45P and an outer connection negative electrode terminal 45N. To a side wall 22B of the upper case 22, an outer connection connector 50 is previously attached. The outer connection connector 50 comprises: an outer connection positive electrode bus bar 52 of which one end is fastened to the outer connection positive electrode terminal 45P; and an outer connection negative electrode bus bar 53 of which one end is fastened to the outer connection negative electrode terminal 45N. In the battery pack 10, the upper case 22 is attached to the lower case 21 so that the one end of the outer connection positive electrode bus bar 52 and the outer connection positive electrode terminal 45P are arranged so as to be fastened and the one end of the outer connection negative electrode bus bar 53 and the outer connection negative electrode terminal 45N are arranged so as to be fastened.SELECTED DRAWING: Figure 17

Description

[Technical Field]

[0001] The present disclosure relates to a battery pack. [Background technology]

[0002] A known example of a battery pack for an automobile is the battery pack described in JP 2020-87913 A (Patent Document 1 below). This battery pack includes a housing, a lid, a battery assembly, and an end assembly. The housing has a first storage chamber, and the lid covers the housing, and the lid has a second storage chamber. The battery assembly is housed in a sealed space formed by the first storage chamber and the second storage chamber. The end assembly includes a panel and two or more connectors fixed to the panel. The battery assembly is electrically connected to a device outside the sealed space, such as another battery pack or a high-voltage box, by the connectors. The panel is hermetically connected to the housing or the lid, and is connected to the housing via a bracket.

[0003] When assembling the battery pack, the battery assembly is fixed to the housing, and the end assembly is attached to the housing via a bracket. After the connector in the end assembly passes through the window in the lid, the lid is covered by the housing and the two are hermetically connected using fasteners and a sealing ring. After that, the panel of the end assembly and the lid are hermetically connected, and for example, a sealing ring is provided between the window and the panel, and a sealing adhesive or the like is applied. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-87913 Summary of the Invention [Problem to be solved by the invention]

[0005] In the battery pack described above, the bracket is covered by the lid, which increases the size of the lid and hinders efforts to reduce the size of the battery pack. One possible way to reduce the size of the battery pack is to eliminate the bracket and directly attach the end assembly to the lid. However, if the end assembly is attached to the lid and then the lid is attached to the housing, connecting the end assembly and the battery assembly becomes difficult. This is because the end assembly and the battery assembly are usually connected using metal plates such as bus bars, which requires a separate fastening process.

[0006] Even if the lid were provided with an opening for fastening work separate from the window for attaching the end assembly, assembly space would be required inside the lid to assemble the end assembly to the lid so that the bus bar faces the opening from the end assembly.Furthermore, the end assembly would need to be assembled to the lid so that one end of the bus bar can connect to the battery assembly.Therefore, various challenges remain to be overcome in order to enable the operation of fastening one end of the bus bar to the battery assembly. [Means for solving the problem]

[0007] The battery pack of the present disclosure includes: an assembled battery formed by stacking cells having positive and negative electrode terminals; a flat lower case on which the assembled battery is placed; an upper case in the shape of a box that opens downwards and is attached to the lower case from above to house the assembled battery together with the lower case; and a bus bar module attached to the upper surface of the assembled battery and accommodating a plurality of internal connection bus bars that connect the positive electrode terminal and the negative electrode terminal, the bus bar module including an external connection positive terminal connected to the positive electrode terminal and an external connection negative terminal connected to the negative electrode terminal, an external connection connector is attached in advance to a side wall of the upper case, the external connection connector including an external connection positive bus bar having one end fastened to the external connection positive terminal and an external connection negative bus bar having one end fastened to the external connection negative terminal, an opening is formed in the top wall of the upper case to expose one end of the external connection positive bus bar and one end of the external connection negative bus bar to the outside, and the upper case is attached to the lower case such that one end of the external connection positive bus bar and the external connection positive terminal are arranged to be fastenable to each other, and one end of the external connection negative bus bar and the external connection negative terminal are arranged to be fastenable to each other. [Effects of the Invention]

[0008] According to the present disclosure, the battery pack can be made smaller and the energy density of the battery pack can be improved. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of the battery pack as seen obliquely from above and in front. [Figure 2] FIG. 2 is a perspective view of the battery pack as seen obliquely from below and behind. [Figure 3] FIG. 3 is a perspective view of the lower case. [Figure 4] FIG. 4 is a perspective view showing a state in which the battery pack is placed on the upper surface of the lower case. [Figure 5]FIG. 5 is a perspective view showing a state in which a bus bar module is attached to the upper surface of the battery pack. [Figure 6] FIG. 6 is a perspective view showing a state in which the upper case, to which the external connection connector has been previously attached, is attached to the lower case from above. [Figure 7] FIG. 7 is a partially enlarged plan view of a part of FIG. 6 as viewed from above. [Figure 8] FIG. 8 is a perspective view of the upper case. [Figure 9] FIG. 9 is a perspective view of the upper case to which the external connector is attached in advance, as seen obliquely from above. [Figure 10] FIG. 10 is a perspective view of the upper case to which the external connector is attached in advance, as seen obliquely from below. [Figure 11] 11 is a partially enlarged plan view of the external connector of FIG. 9, viewed from above. [Figure 12] 12 is a partially enlarged front view of the external connector of FIG. 9, as viewed from the front. [Figure 13] 13 is a partially enlarged rear view of the external connection connector of FIG. 9, seen from the rear. [Figure 14] FIG. 14 is a plan view showing a state in which a bus bar module is attached to the upper surface of the battery pack. [Figure 15] FIG. 15 is a plan view showing the internal structure of the bus bar module of FIG. [Figure 16] FIG. 16 is a cross-sectional view showing the internal structure of the battery pack. [Figure 17] FIG. 17 is a cross-sectional view showing a fastening structure between the second connection portion of the external connection positive electrode bus bar and the external connection positive electrode terminal. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. (1) A battery pack disclosed herein includes an assembled battery formed by stacking cells having positive and negative electrode terminals; a flat lower case on which the assembled battery is placed; an upper case that is box-shaped and opens downward and is attached to the lower case from above to house the assembled battery together with the lower case; and a bus bar module that is attached to the upper surface of the assembled battery and houses a plurality of internal connection bus bars that connect the positive electrode terminals and the negative electrode terminals, the bus bar module including an external connection positive terminal connected to the positive electrode terminal and an external connection negative terminal connected to the negative electrode terminal, and the upper case an external connection connector is attached in advance to a side wall of the upper case, the external connection connector including an external connection positive bus bar having one end fastened to the external connection positive terminal and an external connection negative bus bar having one end fastened to the external connection negative terminal; an opening is formed in an upper wall of the upper case to expose one end of the external connection positive bus bar and one end of the external connection negative bus bar to the outside; the upper case is attached to the lower case so that one end of the external connection positive bus bar and the external connection positive terminal are arranged to be fastenable to each other, and one end of the external connection negative bus bar and the external connection negative terminal are arranged to be fastenable to each other.

[0011] In the battery pack described above, the external connector is not attached to the upper case via a bracket but is fixed directly to the upper case, which allows the battery pack to be downsized by the amount of the bracket, thereby improving the energy density of the battery pack. Furthermore, since the external connector is attached to the upper case in advance, and the upper case is attached to the lower case so that one end of the external connection positive bus bar and the external connection positive terminal can be fastened together, and one end of the external connection negative bus bar and the external connection negative terminal can be fastened together, no assembly space is required inside the upper case, further reducing the size of the battery pack.

[0012] (2) Preferably, the bus bar module includes a protector that holds the plurality of internal connection bus bars, the protector including a positive terminal insulating wall formed around the external connection positive terminal and a negative terminal insulating wall formed around the external connection negative terminal, and when the upper case is attached to the lower case, one end of the external connection positive bus bar is fitted and housed within the positive terminal insulating wall, and one end of the external connection negative bus bar is fitted and housed within the negative terminal insulating wall. When the upper case is attached to the lower case, one end of the external connection positive bus bar fits into and is housed within the positive terminal insulating wall, thereby positioning one end of the external connection positive bus bar so that it can be fastened to the external connection positive terminal, and one end of the external connection negative bus bar fits into and is housed within the negative terminal insulating wall, thereby positioning one end of the external connection negative bus bar so that it can be fastened to the external connection negative terminal.

[0013] (3) Preferably, the bus bar module includes a control board and a plurality of voltage detection lines connecting the plurality of internal connection bus bars to the control board. Since the voltage-related signals input to the control board can be aggregated using multiple voltage detection wires, the aggregated voltage-related signal can be output to the outside of the battery pack using a single wire.

[0014] (4) It is preferable that a gas flow path be formed between the protector and the battery pack, for discharging gas generated inside the cells to the outside. Since the gas flow path is formed by attaching the bus bar module to the upper surface of the battery pack, there is no need to form a gas flow path separately from the bus bar module.

[0015] [Details of the embodiments of the present disclosure] Specific examples of the connector of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0016] <Embodiment> An embodiment of the present disclosure will be described with reference to Figures 1 to 17. In the following description, the direction indicated by arrow X is the front-to-rear direction, the direction indicated by arrow Y is the left-to-right direction, and the direction indicated by arrow Z is the up-to-down direction. Furthermore, for multiple identical components, reference numerals may be assigned to only some of the components, and the reference numerals for the other components may be omitted.

[0017] [Battery pack] The battery pack 10 of this embodiment is mounted on a vehicle such as a hybrid vehicle powered by an internal combustion engine such as a gasoline engine or a diesel engine and a motor powered by a rechargeable battery, a plug-in hybrid vehicle capable of external charging, or an electric vehicle. The battery pack 10 is provided as a driving power source for these vehicles.

[0018] [Case] 1 and 2, the battery pack 10 includes a housing 20 made up of a flat lower case 21 and a box-shaped upper case 22 that opens downward. The housing 20 has a substantially rectangular parallelepiped block shape. A battery pack 30 shown in FIG. 4 and a bus bar module 40 shown in FIG. 5 are housed inside the housing 20 in a stacked state.

[0019] 2, a safety valve 23 is attached to the rear surface of the upper case 22. The safety valve 23 is connected to a gas flow path 49A, which will be described later, and is configured to release gas within the battery pack 30 to the outside of the housing 20 when the internal pressure of the battery pack 30 reaches a predetermined pressure.

[0020] As shown in Figures 3 and 4, the lower case 21 has an upper surface 21A on which the battery pack 30 is placed, a rectangular tube portion 21B protruding upward from the upper surface 21A, a plurality of mounting holes 21C formed around the rectangular tube portion 21B on the upper surface 21A, and a pair of positioning protrusions 21D.

[0021] 3, the pair of positioning protrusions 21D are formed at a pair of diagonally opposite corners of the four corners of the lower case 21. Meanwhile, a pair of positioning holes 22D are formed through the upper case 22 at positions corresponding to the pair of positioning protrusions 21D. By inserting the pair of positioning protrusions 21D into the pair of positioning holes 22D, the lower case 21 and the upper case 22 are assembled in a properly positioned state.

[0022] A square annular seal ring 24 is attached between the rectangular tube portion 21B and each mounting hole 21C on the top surface 21A of the lower case 21. In the upper case 22, insertion holes 22C (see FIG. 6) for inserting mounting bolts B1 are formed at positions corresponding to each mounting hole 21C.

[0023] The upper case 22 is attached to the lower case 21 from above, and the mounting bolts B1 are inserted into the insertion holes 22C and fastened to the mounting holes 21C, whereby the seal ring 24 is sandwiched between the lower case 21 and the upper case 22. As a result, the lower case 21 and the upper case 22 are fixed together with the gap between them sealed.

[0024] [Battery pack] The battery pack 10 further includes a battery assembly 30. As shown in FIG. 4, the battery assembly 30 is formed by stacking a plurality of cells 31. The cells 31 are composed of batteries (secondary batteries) such as lithium-ion batteries or nickel-metal hydride batteries. The cells 31 are stacked in the front-rear direction (the direction indicated by the arrow X in FIG. 4; hereinafter, also referred to as the "stacking direction of the cells 31").

[0025] The unit cells 31 have a thin plate shape that is approximately rectangular parallelepiped. The multiple unit cells 31 are stacked such that the side surfaces with the largest areas among the multiple side surfaces that form the exterior of the unit cells 31 face each other between the unit cells 31 adjacent to each other in the stacking direction. The multiple unit cells 31 are stacked such that the thickness direction of each unit cell 31 is parallel to the stacking direction of the unit cells 31.

[0026] The battery pack 30 has a rectangular parallelepiped appearance. When viewed from above, the direction in which the long sides of the battery pack 30 extend is parallel to the stacking direction of the cells 31, and the left-right direction in which the short sides of the battery pack 30 extend (the direction indicated by arrow Y in FIG. 4 ) is perpendicular to the stacking direction of the cells 31.

[0027] The battery pack 30 has an upper surface 32 and a plurality of electrode terminals 33. The upper surface 32 is a flat surface that forms the upper portion of the battery pack 30. The plurality of electrode terminals 33 protrude from the upper surface 32. The plurality of electrode terminals 33 are arranged in two rows in the stacking direction of the cells 31.

[0028] More specifically, each cell 31 has a positive electrode terminal 33P and a negative electrode terminal 33N that constitute the electrode terminal 33. In each cell 31, the positive electrode terminal 33P and the negative electrode terminal 33N are arranged apart in the left-right direction. In the battery pack 30, the positive electrode terminals 33P and the negative electrode terminals 33N are arranged alternately in the stacking direction of the cells 31. The positive electrode terminals 33P and the negative electrode terminals 33N that are adjacent in the stacking direction of the cells 31 are connected by an internal connection bus bar 41, which will be described later. The cells 31 are electrically connected in series.

[0029] Each cell 31 further has a release valve 34. The release valve 34 is provided on the top surface 32 of the cell 31, between the positive electrode terminal 33P and the negative electrode terminal 33N. The release valve 34 opens when the pressure of gas generated inside the cell 31 increases, thereby releasing the pressure inside the cell 31. Each release valve 34 is connected to a gas flow path 49A, which will be described later. This allows gas generated inside the cell 31 to be discharged into the gas flow path 49A, and then from the gas flow path 49A to the outside of the casing 20 via the safety valve 23.

[0030] [Busbar module] The battery pack 10 further includes a bus bar module 40. As shown in FIG. 5, the bus bar module 40 is attached to the upper surface 32 of the battery pack 30. As shown in FIG. 15, the bus bar module 40 has a plurality of internal connection bus bars 41. The internal connection bus bars 41 are arranged in two rows in the front-to-rear direction indicated by the arrow X. The arrangement direction of the internal connection bus bars 41 is parallel to the stacking direction of the cells 31.

[0031] The internal connection bus bar 41 is connected to the positive electrode terminal 33P and the negative electrode terminal 33N that are adjacent in the stacking direction of the cells 31. The internal connection bus bar 41 on the left side in the figure and the internal connection bus bar 41 on the right side in the figure are arranged in a staggered pattern in the stacking direction of the cells 31.

[0032] The bus bar module 40 further includes a plurality of voltage detection wires 42. The voltage detection wires 42 are electric wires for detecting the state of the battery pack 30. The voltage detection wires 42 detect the voltage of the battery pack 30. One end of each of the voltage detection wires 42 is connected to one of the plurality of internal connection bus bars 41.

[0033] The busbar module 40 further includes a resin protector 43. The protector 43 includes a box-shaped protector body 43A that opens upward, and a pair of covers 43B that cover the protector body 43A from above. The pair of covers 43B are connected to the left and right sides of the protector body 43A via hinges.

[0034] The protector body 43A holds a plurality of internal connection bus bars 41 and a control board 44. Each internal connection bus bar 41 is held in a position that allows connection to each electrode terminal 33. As a result, when the bus bar module 40 is attached to the upper surface 32 of the battery pack 30, each internal connection bus bar 41 is disposed at the position of the corresponding electrode terminal 33.

[0035] The other ends of the multiple voltage detection wires 42 are connected to a control board 44. Multiple relays 44A, FRAM 44B, output connector 44C, etc. are mounted on the control board 44. Signals related to voltage input from each voltage detection wire 42 to the control board 44 are aggregated and output to an external device from the output connector 44C via a single electric wire.

[0036] 15, the electrode terminal 33 located at the uppermost position among the electrode terminals 33 on the left side of the figure is a positive electrode terminal 33P, which is a total positive electrode terminal 33P1 that is not connected to the internal connection bus bar 41. Furthermore, the electrode terminal 33 located at the lowermost position among the electrode terminals 33 on the right side of the figure is a negative electrode terminal 33N, which is a total negative electrode terminal 33N1 that is not connected to the internal connection bus bar 41.

[0037] An external connection positive terminal 45P and an external connection negative terminal 45N are arranged at the illustrated lower end of the protector body 43A. The external connection positive terminal 45P is arranged to the left of the external connection negative terminal 45N. The external connection positive terminal 45P is configured by the right end of the positive terminal third relay bus bar 46P3. The external connection negative terminal 45N is configured by the left end of the negative terminal relay bus bar 46N. The external connection positive terminal 45P is connected to one end of an external connection positive bus bar 52, which will be described later, and the external connection negative terminal 45N is connected to one end of an external connection negative bus bar 53, which will be described later.

[0038] The total positive terminal 33P1 is connected to one end of an external connection positive bus bar 52 via a positive terminal first relay bus bar 46P1, a control board 44, a positive terminal second relay bus bar 46P2, a fuse 47, and a positive terminal third relay bus bar 46P3. The total negative terminal 33N is connected to one end of an external connection negative bus bar 53 via a negative terminal relay bus bar 46N.

[0039] A gas flow path forming portion 49 extending in the front-rear direction is provided in the center of the protector body 43A in the left-right direction. As shown in Fig. 16, a gas flow path 49A that discharges gas generated inside the cells 31 to the outside is formed between the gas flow path forming portion 49 and the upper surface 32 of the battery pack 30. The release valves 34 of each cell 31 are connected to the gas flow path 49A. The gas flow path 49A extends in the front-rear direction, and the downstream end of the gas flow path 49A is connected to the safety valve 23.

[0040] As shown in Fig. 14, a positive terminal insulating wall 48P and a negative terminal insulating wall 48N are formed on a pair of covers 43B of the protector 43. Each insulating wall 48P, 48N is disposed at the lower end of the pair of covers 43B as shown in the figure. The positive terminal insulating wall 48P is formed around the external connection positive terminal 45P, and the negative terminal insulating wall 48N is formed around the external connection negative terminal 45N. Each insulating wall 48P, 48N is formed by opening a part of the pair of covers 43B, and has a gate shape that opens downward as shown in the figure.

[0041] [External connection connector] 8 and 9, a through-hole 25, through which an external connection connector 50 is disposed, is formed in a side wall 22B of the upper case 22. A plurality of insertion holes 25A are formed in the side wall 22B of the upper case 22 around the through-hole 25. The external connection connector 50 includes a resin housing 51, an external connection positive bus bar 52, and an external connection negative bus bar 53.

[0042] 17, the housing 51 includes a cylindrical housing main body 51A that passes through the through-hole 25 and protrudes to the outside of the upper case 22, and a flange 51B that extends from an end of the housing main body 51A along the inner surface of the upper case 22. A nut (not shown) is housed in the flange 51B, and the external connection connector 50 is fixed to the upper case 22 by inserting a seal screw S through the insertion hole 25A from the outside of the upper case 22 and fastening it to the nut.

[0043] An annular seal ring 54 is sandwiched between the inner surface of upper case 22 and flange 51B. Seal ring 54 is disposed around through hole 25. This prevents water from entering the interior of upper case 22 through through hole 25.

[0044] Because the external connection positive bus bar 52 and the external connection negative bus bar 53 have the same shape, the following description will be directed to the external connection positive bus bar 52. Furthermore, the same configuration of the external connection negative bus bar 53 as that of the external connection positive bus bar 52 will be designated by a reference numeral with the numeral portion changed from 52 to 53.

[0045] The external connection positive bus bar 52 is formed by punching and bending a plate-shaped metal sheet material. As shown in Fig. 17, the external connection positive bus bar 52 includes a first connection portion 52A accommodated in the housing main body 51A, an intermediate connection portion 52B extending upward from an end of the first connection portion 52A, and a second connection portion 52C extending from an end of the intermediate connection portion 52B to the side opposite the first connection portion 52A. A bent portion is formed between the first connection portion 52A and the intermediate connection portion 52B, and a bent portion is formed between the intermediate connection portion 52B and the second connection portion 52C.

[0046] A locking hole 52A1 is formed in the first connection portion 52A. Meanwhile, a lance 51A1 that fits into and locks into the locking hole 52A1 is formed in the housing main body 51A. The lance 51A1 locks into the inner wall of the locking hole 52A1, thereby holding the external connection positive bus bar 52 in the housing 51.

[0047] The housing main body 51A has an accommodating hole 51A2 that accommodates the first connecting portion 52A. A slight clearance is provided between the first connecting portion 52A and the inner wall of the accommodating hole 51A2. This allows for dimensional tolerances and assembly tolerances of each component to be accommodated when connecting the second connecting portion 52C to the external connection positive terminal 45P.

[0048] The distance between the intermediate connection portion 52B and the flange 51B is the same as or slightly larger than the plate thickness of the intermediate connection portion 52B. The distance between the intermediate connection portion 52B and the protector 43 of the bus bar module 40 is also smaller than the plate thickness of the intermediate connection portion 52B. As a result, the space accommodating the intermediate connection portion 52B is quite narrow, and the side wall 22B of the upper case 22, the battery assembly 30, and the bus bar module 40 are arranged in close proximity to each other, thereby reducing the size of the battery pack 10.

[0049] 10 and 11 , the second connection portion 52C of the external connection positive bus bar 52 and the second connection portion 53C of the external connection negative bus bar 53 are both exposed to the outside of the upper case 22 through the opening 26. The external connection positive bus bar 52 and the external connection negative bus bar 53 are both guided by the accommodation hole 51A2 of the housing 51 so as to be movable mainly in the front-rear direction, and their movement in the front-rear direction is suppressed by the lance 51A1, so that they are held at a constant position relative to the housing 51. Therefore, the positions at which the second connection portions 52C and 53C are exposed to the outside of the upper case 22 through the opening 26 are substantially constant.

[0050] When the upper case 22 is attached to the lower case 21 with the external connection connector 50 already attached to the side wall 22B of the upper case 22, the second connection portion 52C of the external connection positive bus bar 52 and the external connection positive terminal 45P are arranged so that they can be fastened together, and the second connection portion 53C of the external connection negative bus bar 53 and the external connection negative terminal 45N are arranged so that they can be fastened together, as shown in Figure 7.

[0051] Each second connection portion 52C, 53C is adapted to be housed in a corresponding insulating wall 48P, 48N. As a result, as shown in Fig. 17, the bolt holes of each second connection portion 52C, 53C, the bolt holes of each terminal 45P, 45N, and the nuts N arranged below each terminal 45P, 45N are arranged coaxially. This allows the connection bolt B2 to be fastened to the nuts N from above each second connection portion 52C, 53C. In other words, simply attaching the upper case 22 to the lower case 21 allows the second connection portions 52C, 53C and the terminals 45P, 45N to be fastened together.

[0052] The opening 26 is closed by an auxiliary cover 27. A seal ring 28 is attached around the periphery of the opening 26. The auxiliary cover 27 has an insertion hole formed in a position corresponding to the mounting hole 26A of the opening 26. By inserting a blocking bolt B3 into the insertion hole of the auxiliary cover 27 and fastening it to the mounting hole 26A of the opening 26, the auxiliary cover 27 is fixed to the top wall 22A of the upper case 22, and the opening 26 is closed by the auxiliary cover 27. In this way, the seal ring 28 is sandwiched between the top wall 22A of the upper case 22 and the auxiliary cover 27, preventing water from entering the interior of the housing 20 through the opening 26.

[0053] [How to assemble the battery pack] First, as a preliminary step before starting assembly of the battery pack 10, the external connector 50 is attached to the upper case 22 with the connection bolt B2. Then, the internal connection bus bar 41, the control board 44, the relay bus bars 46P1, 46P2, 46P3, 46N, and the fuse 47 are assembled inside the protector 43, and the internal connection bus bars 41 and the control board 44 are connected with the voltage detection wires 42, thereby assembling the bus bar module 40.

[0054] After the preliminary preparations are complete, start assembling the battery pack 10. As shown in Fig. 4, the battery pack 30 is placed into the rectangular tube portion 21B of the lower case 21 from above, and the battery pack 30 is placed on the top surface 21A. The rectangular tube portion 21B positions the battery pack 30 in the front-to-back and left-to-right directions, and by placing the battery pack 30 on the top surface 21A, it is placed in a fixed position in the up-down direction.

[0055] Next, as shown in Fig. 5, the bus bar module 40 is attached to the upper surface 32 of the battery pack 30. When the pair of covers 43B are opened, each internal connection bus bar 41 is positioned above the corresponding electrode terminal 33, and the internal connection bus bars 41 are then connected to the electrode terminals 33. This connection may be made by laser welding or bolt fastening.

[0056] Once all fastening connections are complete, the pair of covers 43B are closed. In this state, only the external connection positive terminal 45P of the positive terminal third relay bus bar 46P3 is exposed to the outside from the positive terminal insulating wall 48P, and only the external connection negative terminal 45N of the negative terminal relay bus bar 46N is exposed to the outside from the negative terminal insulating wall 48N. Also, as shown in FIG. 11, it is confirmed that the pair of second connection portions 52C, 53C are positioned in the opening 26.

[0057] Next, the upper case 22, to which the external connection connector 50 has been previously attached, is attached to the lower case 21 from above. At this time, the positioning protrusions 21D are inserted into the positioning holes 22D, and the upper case 22 is placed on the top surface 21A of the lower case 21 while being positioned relative to the lower case 21. Simultaneously with this positioning, the upper case 22 is attached to the lower case 21 so that the pair of second connection portions 52C, 53C are housed inside the pair of insulating walls 48P, 48N, as shown in FIG. 7 . In this manner, the upper case 22 is attached to the lower case 21 so that the second connection portion 52C of the external connection positive bus bar 52 and the external connection positive terminal 45P can be fastened together, and the second connection portion 53C of the external connection negative bus bar 53 and the external connection negative terminal 45N can be fastened together.

[0058] 6, the mounting bolt B1 is inserted into the insertion hole 22C of the upper case 22 and fastened to the mounting hole 21C of the lower case 21. As a result, the seal ring 24 is sandwiched between the lower case 21 and the upper case 22, sealing the gap between the lower case 21 and the upper case 22.

[0059] Once all fastening work is complete, connect the external connection positive bus bar 52 to the external connection positive terminal 45P. As shown in Fig. 7, look inside the upper case 22 through the opening 26 and confirm that the second connection portion 52C of the external connection positive bus bar 52 fits into and is housed inside the positive terminal insulating wall 48P. Similarly, confirm that the second connection portion 53C of the external connection negative bus bar 53 fits into and is housed inside the negative terminal insulating wall 48N.

[0060] Next, the connection bolt B2 is inserted through the bolt hole of the second connection portion 52C of the external connection positive bus bar 52 and the bolt hole of the external connection positive terminal 45P, and is fastened with a nut N, thereby electrically connecting the external connection positive bus bar 52 and the external connection positive terminal 45P (see FIG. 17). Similarly, the connection bolt B2 is inserted through the bolt hole of the second connection portion 53C of the external connection negative bus bar 53 and the bolt hole of the external connection negative terminal 45N, and is fastened with a nut N, thereby electrically connecting the external connection negative bus bar 53 and the external connection negative terminal 45N.

[0061] Next, the opening 26 is closed with the auxiliary cover 27. The closing bolts B3 are inserted into the insertion holes of the auxiliary cover 27 and fastened to the mounting holes 26A arranged around the opening 26. As a result, the seal ring 28 is sandwiched between the auxiliary cover 27 and the top wall 22A of the upper case 22, sealing the gap between the auxiliary cover 27 and the top wall 22A of the upper case 22. Once all fastening operations are complete, the battery pack 10 shown in FIG. 1 is completed.

[0062] [Effects of the embodiment] The battery pack 10 of the present disclosure includes an assembled battery 30 formed by stacking cells 31 having positive and negative electrode terminals 33, a flat lower case 21 on whose top surface 21A the assembled battery 30 is placed, an upper case 22 which is box-shaped and opens downward and is attached to the lower case 21 from above to house the assembled battery 30 together with the lower case 21, and a bus bar module 40 which is attached to the top surface 32 of the assembled battery 30 and houses a plurality of internal connection bus bars 41 which connect the positive electrode terminals 33 and the negative electrode terminals 33, the bus bar module 40 including an external connection positive terminal 45P connected to the positive electrode terminal 33 and an external connection negative terminal 45N connected to the negative electrode terminal 33, and an external connection connector 45B is attached to a side wall 22B of the upper case 22. and an external connection connector (50) is attached in advance to the upper case (22). The external connection connector (50) includes an external connection positive bus bar (52), the second connection portion (52C) ​​of which is fastened to an external connection positive terminal (45P), and an external connection negative bus bar (53), the second connection portion (53C) of which is fastened to an external connection negative terminal (45N). An opening (26) is formed in an upper wall (22A) of the upper case (22) to expose the second connection portion (52C) ​​of the external connection positive bus bar (52) and the second connection portion (53C) of the external connection negative bus bar (53) to the outside. The upper case (22) is attached to the lower case (21) so that the second connection portion (52C) ​​of the external connection positive bus bar (52) and the external connection positive terminal (45P) can be fastened together, and the second connection portion (53C) of the external connection negative bus bar (53) and the external connection negative terminal (45N) can be fastened together.

[0063] According to the above-described battery pack 10, the external connector 50 is not attached to the upper case 22 via a bracket but is fixed directly to the upper case 22, which allows the battery pack 10 to be downsized by the amount of the bracket, thereby improving the energy density of the battery pack 10. Furthermore, the external connector 50 is attached to the upper case 22 in advance, and the upper case 22 is attached to the lower case 21 so that the second connection portion 52C of the external connection positive bus bar 52 and the external connection positive terminal 45P are arranged so as to be fastenable to each other, and the second connection portion 53C of the external connection negative bus bar 53 and the external connection negative terminal 45N are arranged so as to be fastenable to each other. This eliminates the need for assembly space inside the upper case 22, further enabling the battery pack 10 to be downsized.

[0064] The bus bar module 40 includes a protector 43 that holds a plurality of internal connection bus bars 41, and the protector 43 includes a positive terminal insulating wall 48P formed around the external connection positive terminal 45P and a negative terminal insulating wall 48N formed around the external connection negative terminal 45N. When the upper case 22 is attached to the lower case 21, it is preferable that the second connection portion 52C of the external connection positive bus bar 52 is fitted and housed within the positive terminal insulating wall 48P, and the second connection portion 53C of the external connection negative bus bar 53 is fitted and housed within the negative terminal insulating wall 48N.

[0065] When attaching the upper case 22 to the lower case 21, the second connection portion 52C of the external connection positive bus bar 52 fits into and is housed within the positive terminal insulating wall 48P, thereby positioning the second connection portion 52C of the external connection positive bus bar 52 so that it can be fastened to the external connection positive terminal 45P, and the second connection portion 53C of the external connection negative bus bar 53 fits into and is housed within the negative terminal insulating wall 48N, thereby positioning the second connection portion 53C of the external connection negative bus bar 53 so that it can be fastened to the external connection negative terminal 45N.

[0066] The bus bar module 40 preferably includes a control board 44 and a plurality of voltage detection wires 42 connecting the plurality of internal connection bus bars 41 and the control board 44 . Since the signals relating to the voltage input to the control board 44 can be aggregated by the multiple voltage detection wires 42, the aggregated signals relating to the voltage can be output to the outside of the battery pack 10 by a single wire.

[0067] It is preferable that a gas flow path 49A is formed between the protector 43 and the battery pack 30 to discharge gas generated inside the cells 31 to the outside. Since the gas flow passage 49A is formed by attaching the bus bar module 40 to the upper surface 32 of the battery pack 30, it is not necessary to form the gas flow passage 49A separately from the bus bar module 40.

[0068] <Other embodiments> (1) In the above embodiment, the bus bar module 40 includes the protector 43, but the bus bar module may not include a protector.

[0069] (2) In the above embodiment, the voltage detection line 42 is formed of an electric wire, but the voltage detection line may be formed of a flexible printed circuit board.

[0070] (3) In the above embodiment, the gas flow path 49A is formed between the protector 43 and the battery pack 30, but the gas flow path may be formed by a member separate from the protector. [Explanation of symbols]

[0071] 10: Battery pack 20: Housing 21: Lower case 21A: Top surface 21B: Square tube portion 21C: Mounting hole 21D: Positioning protrusion 22: Upper case 22A: Top wall 22B: Side wall 22C: Insertion hole 22D: Positioning hole 23: Safety valve 24: Seal ring 25: Through hole 25A: Insertion hole 26: Opening 26A: Mounting hole 27: Auxiliary cover 28: Seal ring 30: Battery pack 31: Cell 32: Top surface 33: Electrode terminal 33P: Positive electrode terminal 33P1: Total positive electrode terminal 33N: Negative electrode terminal 33N1: Total negative electrode terminal 34: Release valve 40: Busbar module 41: Internal connection busbar 42: Voltage detection wire 43: Protector 43A: Protector body 43B: Cover 44: Control board 44A: Relay 44B: FRAM 44C: Output connector 45P: External connection positive terminal 45N: External connection negative terminal 46P1: Positive terminal first relay busbar 46P2: Positive terminal second relay busbar 46P3: Positive terminal third relay busbar 46N: Negative terminal relay busbar 47: Fuse 48P: Positive terminal insulating wall 48N: Negative terminal insulating wall 49: Gas flow path configuration part 49A: Gas flow path 50: External connection connector 51: Housing 51A: Housing body 51A1: Lance 51A2: Receiving hole 51B: Flange 52: External connection positive bus bar 52A: First connection portion 52A1: Locking hole 52B: Intermediate connection portion 52C: Second connection portion (one end) 53: External connection negative bus bar 53A: First connection portion 53B: Intermediate connection portion 53C: Second connection portion (one end) 54: Seal ring B1: Mounting bolt B2: Connection bolt B3: Blocking bolt N: Nut S: Seal screw

Claims

1. a battery pack formed by stacking unit cells each having a positive electrode terminal and a negative electrode terminal; a planar lower case on which the battery pack is placed; an upper case that is box-shaped and opens downward, that is attached to the lower case from above, and that houses the battery pack together with the lower case; a bus bar module attached to an upper surface of the battery pack and accommodating a plurality of internal connection bus bars that connect the positive electrode terminal and the negative electrode terminal, the busbar module includes an external connection positive electrode terminal connected to the positive electrode terminal and an external connection negative electrode terminal connected to the negative electrode terminal, An external connector is attached to the side wall of the upper case in advance, the external connection connector includes an external connection positive bus bar, one end of which is fastened to the external connection positive terminal, and an external connection negative bus bar, one end of which is fastened to the external connection negative terminal; an upper wall of the upper case has openings that expose one end of the external connection positive bus bar and one end of the external connection negative bus bar to the outside; the upper case is attached to the lower case so that one end of the external connection positive bus bar and the external connection positive terminal are arranged so as to be fastenable to each other, and one end of the external connection negative bus bar and the external connection negative terminal are arranged so as to be fastenable to each other.

2. the bus bar module includes a protector that holds a plurality of the internal connection bus bars; the protector includes a positive electrode terminal insulating wall formed around the external connection positive electrode terminal and a negative electrode terminal insulating wall formed around the external connection negative electrode terminal, 2. The battery pack according to claim 1, wherein, when the upper case is attached to the lower case, one end of the external connection positive bus bar is fitted and housed within the positive terminal insulating wall, and one end of the external connection negative bus bar is fitted and housed within the negative terminal insulating wall.

3. 3. The battery pack according to claim 1, wherein the bus bar module comprises: a control board; and a plurality of voltage detection lines connecting the plurality of internal connection bus bars to the control board.

4. The battery pack according to claim 2 , wherein a gas flow path is formed between the protector and the battery pack, for discharging gas generated inside the cells to the outside.

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