Battery pack

Abstract

An objective of the present invention is to provide a battery pack in which it is possible to prevent disconnection of a voltage detection wire without using any new components or the like.　The battery pack includes a voltage detection electric wire having first voltage detection electric wires 21a1 that start from electrode junction terminals 25 and that are for detecting the voltage of each unit battery, a second voltage detection electric wire 21a2 to which the first voltage detection electric wires are connected so as to branch off midway along, and a splice terminal 27 crimped to the connecting part of the first voltage detection electric wires 21a1 and the second voltage detection electric wire 21a2, wherein the voltage detection electric wire 21a including the splice terminal 27 is disposed in an electric wire routing path 24c of an electric wire storage box 24, and folded excess length portions 28 are formed in the first voltage detection electric wires 21a1 between the electrode junction terminals 25 and the splice terminal 27.

Description

battery pack

[0001] The present invention relates to a battery pack formed by connecting a plurality of unit batteries, and more particularly to a battery pack provided with status detection wires connected to detectors that detect the status (e.g., voltage status) of each unit battery.

[0002] For example, electrolyte batteries including a positive electrode layer capable of absorbing / desorbing lithium ions and a negative electrode layer are widely used as high-energy-density batteries in various fields such as electric vehicles, hybrid vehicles, and power storage. Known electrolyte batteries include those that use a liquid electrolyte and those that use a solid electrolyte.

[0003] A secondary battery using an electrolyte battery is composed of a battery pack consisting of multiple unit cells (electrolyte cells) connected together. This battery pack can generate large amounts of power by electrically connecting the unit cells with electrode members (hereinafter referred to as bus bars) made of conductive metals such as aluminum, copper, and iron.

[0004] The battery pack also has a pair of external terminals that enable the exchange of power, and the bus bars and the pair of external terminals are made of insulating materials, mainly made of engineering plastics, that insulate adjacent bus bars from each other and from high-voltage components including the external terminals.

[0005] The battery pack includes voltage detection wires connected to bus bars to detect the voltage of each unit battery. The voltage information of the unit batteries is acquired from the voltage detection wires and sent to a control means, which uses the information to control the charging and discharging of the battery pack. Batteries installed in automobiles, in particular, are used in a wide range of environmental temperatures, from low to high. Since the input / output characteristics and life characteristics of the battery are temperature-dependent, voltage information is necessary to appropriately control the charging and discharging of the battery pack.

[0006] A known technology for a battery pack equipped with such a voltage detection wire is described in, for example, Japanese Patent Laid-Open No. 2019-139925 (Patent Document 1). This patent document discloses a battery pack including a plurality of battery cells, a case for housing the battery cells, a plurality of voltage detection wires, one end of which is electrically connected to the electrode connection terminals of each of the battery cells, a first connector for bundling the other ends of the voltage detection wires together, a second connector into which the first connector is inserted, and a circuit board on which the second connector is mounted, the case and the circuit board facing each other, and the first connector is inserted into the second connector in a direction along the surface of the circuit board facing the case.

[0007] Japanese Patent Application Laid-Open No. 2019-139925

[0008] In a battery pack equipped with a plurality of voltage detection wires of this type, a wiring configuration is sometimes adopted in which the copper wires constituting the voltage detection wires branch off to other copper wires midway when viewed from the electrode connection terminal of the bus bar. For this reason, it is preferable that unnecessary force not be applied to the branched portion due to excessive or repeated movement caused by a tensile load or repeated load acting on the voltage detection wires leading to the electrode connection terminal of the bus bar.

[0009] Although the embodiment described below focuses on a voltage detection wire, other detection wires, such as a temperature detection wire for detecting the temperature of a unit battery, may also have the same problem. Therefore, voltage detection wires and temperature detection wires can be generalized and referred to as "status detection wires."

[0010] An object of the present invention is to provide a battery pack having a highly reliable state detection wire.

[0011] The present invention is characterized in that it comprises a status detection wire including a plurality of stacked unit batteries, a first status detection wire having a status detection terminal for detecting the status of each unit battery, and a second status detection wire branched from a branch portion formed in the middle of the first status detection wire, and the plurality of status detection wires including the branch portion are arranged in a wire routing path of a wire storage box, and further, a folded excess portion is formed in the first status detection wire between the status detection terminal and the branch portion.

[0012] The present invention is also characterized in that it comprises a status detection electric wire including a plurality of stacked unit batteries, a first status detection electric wire starting from a status detection terminal for detecting the status of each unit battery, a second status detection electric wire connected to the first status detection electric wire so as to branch midway, and a splice terminal crimped to the connection portion of the first status detection electric wire and the second status detection electric wire, the status detection electric wire including the splice terminal being arranged in a wire routing path of a wire storage box, and a folded-back excess portion being formed in the first status detection electric wire between the status detection terminal and the splice terminal.

[0013] In the present invention, the branch portion is arranged in the electric wire routing path, which prevents the branch portion from moving, and the folded-back excess length portion is formed, which provides a battery pack with a highly reliable state detection mechanism. This makes it possible to prevent force from acting on the branch portion even when a tensile load or repeated load is applied.

[0014] 1 is an exploded perspective view of a battery pack according to an embodiment to which the present invention is applied; FIG. 2 is an external top view of the battery pack shown in FIG. 1; FIG. 3 is an external side view of the battery pack shown in FIG. 1; FIG. 4 is a sectional perspective view of the battery pack shown in FIG. 2 taken along the line A-A, as viewed obliquely from above; FIG. 5 is a sectional perspective view of the battery pack shown in FIG. 2 taken along the line B-B, as viewed obliquely from above; FIG. 6 is a perspective view of a wire storage box, a voltage detection wire, and a bus bar as viewed obliquely from above; FIG. 7 is an enlarged perspective view of a portion Q shown in FIG. 7 taken obliquely from above; FIG. 8 is an explanatory diagram illustrating the relationship between the wire routing path and the folded-back excess length portion;

[0015] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the following embodiment and includes various modifications and applications within the technical concept of the present invention. Note that the following description will be given taking a voltage detection wire as an example of a status detection wire.

[0016] Before describing the embodiments of the present invention, a brief description will be given of the configuration of the battery pack to which the present invention is applied. Fig. 1 is an exploded perspective view of an assembled battery according to an embodiment of the present invention, viewed obliquely from above, Fig. 2 is a top view of the assembled battery, viewed from above, Fig. 3 is a side view thereof, Fig. 4 is a cross-sectional perspective view of the A-A section of Fig. 2, viewed obliquely from above, Fig. 5 is a cross-sectional perspective view of the B-B section of Fig. 2, viewed obliquely from above, and Fig. 6 is a perspective view of the wire storage box removed, viewed obliquely from above.

[0017] 1 to 6, the housing 11 constituting the battery pack 10 has a generally elongated rectangular parallelepiped shape with its longitudinal dimension greater than its lateral and height dimensions, and holds a plurality of unit batteries 13 (see FIG. 4) that constitute the battery group 12 (see FIG. 4).

[0018] More specifically, as shown in FIG. 1 , the battery pack according to this embodiment is composed of a plurality of unit batteries 13 (battery group), a pair of end plates 15 and side plates 16 that surround the unit batteries 13 from the outside, a bus bar case 17 made of synthetic resin that covers the top surfaces of the unit batteries 13, bus bars 23 that are housed in the bus bar case 17 and connected to the electrode terminals of the unit batteries 13, a wire storage box (also referred to as a harness case below) 24 that houses a bundle of wires (also referred to as a harness below) that are connected to the bus bars 23 and extract a detected voltage signal to the outside, and a bus bar cover 18 that is fixed to the top surfaces of the end plates 15 and side plates 16 so as to cover the harness case 24, the bus bars 23, and the bus bar case 17.

[0019] The bus bar 23 has end bus bars 23E at both ends, and is connected to external electrical equipment via these end bus bars 23E. The unit batteries 13 are held in cell holders 14 made of synthetic resin. Spacers 31 are interposed between the end plates 15 and the unit batteries 13, and similarly, spacers 31 are interposed between each unit battery 13 and an adjacent unit battery 13. An intermediate plate 13M is disposed midway between the multiple unit batteries 13 stacked along the longitudinal direction of the side plates 16.

[0020] 5, the unit battery 13 is formed in a rectangular parallelepiped shape, and as is well known, a positive electrode terminal 32(+) and a negative electrode terminal 32(-) are provided on the top surface along a direction perpendicular to the stacking direction. The top surface faces the bus bar case 17. The unit battery 13 is composed of a container 34 and a lid 35, and the container 34 contains a current collector and an electrolyte.

[0021] The lid 35 seals the current collector and the electrolyte together with the container 34. The lid 35 is joined to the container 34. A positive electrode terminal 32(+) and a negative electrode terminal 32(-) are attached to the lid 35. The bus bar 23 is welded to the positive electrode terminal 32(+) and the negative electrode terminal 32(-) by a method such as ultrasonic welding.

[0022] In addition, a gas release valve 33, which is a safety valve, is provided on the lid 35 between the positive terminal 32(+) and the negative terminal 32(-), and breaks open outward when the internal pressure in the unit battery 13 exceeds a predetermined value. The gas release valve 33 is thin and integrally formed with part of the lid 35.

[0023] 2 and 3, the housing 11 includes a plurality of cell holders 14 (see FIG. 4) that hold the unit batteries 13, a pair of end plates 15, a pair of side plates 16, a bus bar case 17, and a bus bar cover 18. As shown in FIG. 3, the end plates 15 and the side plates 16 are firmly fixed together with fixing members such as fixing bolts and rivets. The unit batteries 13 incorporate battery elements therein, including an electrolyte, a positive electrode layer, and a negative electrode layer. The electrolyte may be liquid or solid.

[0024] The cell holder 14 shown in Fig. 4 is made of a resin material, such as polybutylene terephthalate (PBT). The cell holder 14 is interposed between adjacent unit batteries 13 of the multiple unit batteries 13 stacked in the longitudinal direction, and holds each unit battery 13 by sandwiching it from both sides in the thickness direction (the longitudinal direction of the housing).

[0025] The pair of end plates 15 are metal plate-shaped members and are arranged on either side of the battery group 12 in the stacking direction of the multiple unit batteries 13 that make up the battery group 12, with a pair of cell holders 14 interposed between them. One surface of each of the pair of end plates 15 faces each other so as to sandwich the multiple unit batteries 13 held by the cell holders 14, and a fixing portion is provided on the other surface facing outward, opposite the battery group 12.

[0026] The fixing portions 15a provided on the pair of end plates 15 are formed in a generally cylindrical shape, with part of the cylindrical side surface extending forward or backward from the outer flat surface of the end plate 15. The fixing portions 15a have bolt holes along a central axis that is parallel to the height direction (up-down direction) of the end plate 15.

[0027] The fixing portion 15a of the end plate 15 is a fixing member attachment portion for fixing the battery pack 10 to an external mechanism such as a vehicle or other machine. The lower end surface of the fixing portion 15a of the end plate 15 is a support surface of the housing 11 that is supported by the external mechanism.

[0028] That is, the battery pack 10 can be fixed to the external mechanism by supporting the support surface of the housing 11, which is the bottom surface of the fixing portion 15a of the end plate 15, with the external mechanism, and fastening the bolts inserted into the bolt holes of the fixing portion 15a with female threads or nuts on the external mechanism. In other words, the battery pack 10 is fixed to the external mechanism with the bolts, and is supported by the external mechanism at least by the support surface of the housing 11, which is the bottom surface of the fixing portion 15a of the end plate 15.

[0029] The pair of side plates 16 are arranged via cell holders 14 on both sides in the width direction of the plurality of unit batteries 13 that make up the battery group 12. The pair of side plates 16 are roughly rectangular plate-shaped metal members, and are arranged on both sides in the width direction of the housing 11 so as to face each other and sandwich the battery group 12 therebetween.

[0030] The pair of side plates 16 are roughly rectangular, with the stacking direction of the multiple unit batteries 13 that make up the battery group 12 being the long side direction, i.e., the longitudinal direction, and the height direction of the multiple unit batteries 13 that make up the battery group 12 being the short side direction, i.e., the lateral direction.

[0031] Both longitudinal ends of the pair of side plates 16 are fastened to the pair of end plates 15 by fastening members such as rivets or bolts. Both lateral ends of the pair of side plates 16 are engaged with concave grooves provided in the cell holder 14.

[0032] The bus bar cases 17 (see FIGS. 1 and 3 ) are plate-shaped members made of electrically insulating resin such as PBT and having a predetermined rigidity, and are disposed opposite each other on the upper end surfaces of the battery containers on which the cell positive and negative terminals of the unit batteries 13 are provided. Note that the predetermined rigidity means a degree of rigidity that prevents unnecessary deformation when the bus bar cases 17 are attached to the battery pack 10. In other words, it is sufficient for the bus bar cases 17 to have sufficient rigidity.

[0033] An electric wire outlet tube 20 is exposed from the top surface of the bus bar cover 18, and various electric wire bundles 21a to 21c are drawn out from this portion. Connection sockets 22a to 22c are provided at the ends of the electric wire bundles 21a to 21c, and are connected to control means (not shown). An electric wire bundle 21a (hereinafter referred to as a voltage detection electric wire) that detects the voltage of the unit battery of this embodiment is also drawn out from the electric wire outlet tube 20. The voltage detection electric wire 21a can move freely relative to the electric wire outlet tube 20, and this movement is also transmitted to the voltage detection electric wire 21a arranged in an electric wire storage box (described later).

[0034] The voltage detection wire 21a is composed of a coating made of a flexible insulating synthetic resin and an electrically conductive copper wire covered with this coating. However, for convenience of explanation, the voltage detection wire may hereinafter be referred to as the coated copper wire or the copper wire itself.

[0035] 5 , the bus bar case 17 has openings that expose the upper end surfaces of the positive electrode terminals 32(+) and negative electrode terminals 32(-) of the multiple unit batteries 13, and partition walls 17W that provide insulation between the positive electrode terminals 32(+) and negative electrode terminals 32(-) of adjacent unit batteries 13 and between adjacent bus bars. The partition walls 19 of the bus bar case 17 are provided to surround the peripheries of the 32(+) and negative electrode terminals 32(-) of the unit batteries 13 and the bus bars 23.

[0036] The battery group 12 (see FIG. 4 ) is constructed by stacking flat rectangular unit batteries 13, i.e., thin hexahedral or rectangular unit batteries 13 whose thickness is smaller than their width and height, in the longitudinal direction of the side plates 16. The unit batteries 13 are rectangular lithium-ion batteries and include a flat rectangular battery container, an electrode group (not shown) housed inside the battery container, an electrolyte solution or a solid electrolyte sheet, and a pair of cell electrode terminals connected to the electrode group and located on the upper end surface of the battery container in the height direction. Here, as described above, the pair of cell electrode terminals is the positive terminal 32(+) and the negative terminal 32(-).

[0037] A pair of cell electrode terminals of the unit battery 13 has a three-dimensional, roughly rectangular parallelepiped shape that protrudes in the height direction from the upper end surface of the lid 35 of the battery container. The pair of cell electrode terminals and the battery container, and the battery container and the electrode group are electrically insulated by resin insulating members. The multiple unit batteries 13 that make up the battery group 12 are stacked in such a way that the positive electrode terminal 32(+) of one adjacent unit battery 13 and the negative electrode terminal 32(-) of the other unit battery 13 are alternately rotated 180° in the stacking direction so that they are adjacent to each other.

[0038] The bus bars 23 are connecting conductors that electrically and mechanically connect the unit batteries 13 of the battery group 12 and also electrically and mechanically connect the battery group 12 to external terminals. The bus bars 23 that electrically and mechanically connect the unit batteries 13 of the battery group 12 are multiple bus bars that electrically and mechanically connect the unit batteries 13 together, and are joined by welding to the upper end surfaces of the cell electrode terminals of the unit batteries 13 of the battery group 12 that are exposed at the openings of the bus bar case 17.

[0039] Of a pair of unit batteries 13 adjacent to each other in the stacking direction, the cell positive terminal of one unit battery 13 is electrically connected to the cell negative terminal of the other unit battery 13 by a bus bar 23, thereby forming a battery group 12 in which all unit batteries 13 are electrically connected in series.

[0040] Returning to Figure 2, the bus bar cover 18 is a plate-shaped member made of electrically insulating resin such as PBT, and is arranged to cover the bus bar case 17 at the upper end of the housing 11 on the opposite side of the battery group 12 in the height direction (vertical direction) of the housing 11.

[0041] 5, a harness case 24 extending in the longitudinal direction of the housing 11 is disposed near the center of the upper part of the housing 11. The harness case 24 includes an upper plate 24a extending in the longitudinal direction and located on the opposite side to the battery group 12, and a side plate 24b extending in the longitudinal direction and connected to the upper plate 24a, and a harness storage section (hereinafter also referred to as an electric wire routing path) 24c extending in the longitudinal direction, which is a storage space for wiring, is formed between the upper plate 24a and the side plate 24b.

[0042] The top plate 24a and both side plates 24b are arranged to surround the electric wire routing path 24c from above and from the sides. A plurality of voltage detection wires 21a are housed in the electric wire routing path 24c. The top plate 24a also has an opening (through hole) 30 formed therein, which functions to diffuse gas discharged when a gas discharge valve formed on the top surface of the unit battery 13 is opened.

[0043] 6 shows the configuration of the harness case 24, the voltage detection wires 21a, and the electrode junction terminals (which also serve as status detection terminals / voltage detection terminals) 25 for detecting the voltage status. The harness case 24 is made of synthetic resin and includes a top plate 24a, a pair of side plates 24b connected to the top plate 24a at a 90° angle, and a wire routing path 24c (see FIGS. 7 and 8) formed by these plates. The wire routing path 24c is formed in two rows in the longitudinal direction of the harness case 24, and coincides with the arrangement direction of the bus bars 23 arranged along the longitudinal direction of the harness case 24.

[0044] The voltage detection wires 21a are drawn out from the wire routing paths 24c to the side plate 24b so as to correspond to the positions of the cell electrode terminals of the unit batteries 13, and are joined to the electrode joining terminals 25. The drawn-out voltage detection wires 21a are held inside a wire holder 26, which is fixedly held on the side plate 24b.

[0045] The voltage detection wire 21a and the electrode joint terminal 25 are electrically and mechanically connected in advance by crimping or the like. The electrode joint terminal 25 is electrically joined to the bus bar 23 by ultrasonic welding. This ultrasonic welding is performed after the harness case 24 is attached to the upper side of the battery pack 12.

[0046] The above-described electric wire routing path 24c has the following characteristics. The electric wire routing path 24c extends in the stacking direction of the unit batteries 13. The electric wire routing path 24c extends in a direction passing between the positive electrode terminal 32(+) and the negative electrode terminal 32(-) of the unit battery 13. The electric wire routing path 24c is formed farther from the end of the unit battery 13 than the positive electrode terminal 32(+) or the negative electrode terminal 32(-). In other words, the electric wire routing path 24c is located between the positive electrode terminal 32(+) and the negative electrode terminal 32(-) of the unit battery 13. The electric wire routing path 24c is also located in the stacking direction of the unit batteries 13 (the longitudinal direction of the side plates 16) on both sides of the gas release valve 33, which opens when the internal battery pressure exceeds a predetermined value. Furthermore, the openings 30 formed in the harness case 24 are located at positions corresponding to the gas release valves 33.

[0047] In the voltage detection wire having the above-described configuration, a wiring configuration may be adopted in which the copper wire constituting the voltage detection wire 21a branches off into another copper wire midway when viewed from the electrode joining terminal 25 connected to the bus bar 23. Then, for example, in order to ensure a reliable wiring connection at this branched portion, the copper wire at the branched portion is joined by a splice terminal.

[0048] However, because the splice terminal secures the copper wires at the branched portion by crimping, the copper wires are crushed. Therefore, if an excessive tensile load or repeated load is applied to the voltage detection wire 21a leading to the electrode connection terminal 25 joined to the bus bar 23, it is desirable to prevent the branched portion of the splice terminal from moving excessively or repeatedly, resulting in unnecessary stress being applied to the branched portion. In particular, reliable measurement of battery voltage in products such as assembled batteries is desirable for controlling the charge and discharge of the assembled batteries.

[0049] In order to address these issues, this embodiment proposes a battery pack that includes a voltage detection wire having a first voltage detection wire that starts from an electrode junction terminal for detecting the voltage of each unit battery, a second voltage detection wire that is connected to the first voltage detection wire so that it branches off midway, and a splice terminal that is crimped and attached to the connection portion of the first voltage detection wire and the second voltage detection wire, and the voltage detection wire including the splice terminal is arranged in a wire routing path in a wire storage box, and a folded-back excess portion is formed in the first voltage detection wire between the electrode junction terminal and the splice terminal.

[0050] Further, for example, the battery pack may include a battery group in which unit batteries are stacked so that the positive electrode terminals or the negative electrode terminals face one side, a voltage detection wire for detecting the voltage of the unit batteries, and a wire housing box having a wire routing path for housing the plurality of voltage detection wires, wherein the voltage detection wire is connected to an electrode junction terminal for detecting the voltage of one unit battery and includes a first voltage detection wire connected to a first output portion, a branch portion formed midway on the first voltage detection wire, and a second voltage detection wire branched from the branch portion and connected to a second output portion, wherein the plurality of voltage detection wires include a voltage detection wire having a folded excess length formed between the electrode junction terminal of the first voltage detection wire and the branch portion, and the wire routing path extends along a first direction in which the unit batteries are stacked, and the wire routing path houses the first status detection wire, the second status detection wire, the branch portion, and the excess length.

[0051] An embodiment of the present invention will be described below with reference to Figures 7 and 8. Figure 7 shows only the harness case 24, and Figure 8 shows an enlarged view of part Q in Figure 7. Note that part Q is shown with a portion of the side plate 24b cut away, and the wire holder is also omitted.

[0052] 6, a number of voltage detection wires 21a connected to electrode junction terminals 25 are housed in a wire routing path 24c formed by an upper plate 24a and a pair of side plates 24b of a harness case 24. These voltage detection wires 21a are collected in a wire draw-out tube 20, drawn out to the outside, and connected to a connection socket 22a.

[0053] One end of the voltage detection wire 21a is connected to the electrode junction terminal 25, and a first voltage detection wire 21a1 is connected to the connection socket 22a, which is the first output portion, via a branched splice terminal 27. A second voltage detection wire 21a2 branches off from the splice terminal 27 formed midway on the first voltage detection wire 21a1 and is connected to the connection socket 22b, which is the second output portion.

[0054] In this embodiment, an example has been described in which a signal from one electrode junction terminal 25 is output from connection socket 22a and connection socket 22b, but connection socket 22a may also have an output terminal from the first voltage detection wire 21a1 and an output terminal from the second voltage detection wire 21a2.

[0055] In addition, the first voltage detection wire 21a1 has been described as including both the wiring on the electrode junction terminal 25 side of the branch and the wiring on the connection socket 22a side. This includes not only a voltage detection wire made of a continuous wire, but also a voltage detection wire in which different wires are joined at a predetermined branch and connected to a connection socket.

[0056] The electric wire routing path 24c formed in the harness case 24 is a groove having a U-shaped cross section formed by the side plate 24b and the top plate 24a as described above, and many voltage detection electric wires 21a are arranged in this groove. This state will be explained with reference to FIG.

[0057] 7, a plurality of voltage detection wires 21a are arranged in the wire routing path 24c. Some of these voltage detection wires 21a include a first voltage detection wire (first copper wire) 21a1 that is crimped and connected to the electrode junction terminal 25. The voltage detection wire 21a1 starts from the electrode junction terminal 25, and is branched off by being joined to another second voltage detection wire (second copper wire) 21a2 midway.

[0058] At this joint, the coating is stripped off and the copper wires are wound around and joined. At this branched portion, a splice terminal 27 is crimped to the connection portion of the copper wires of the first voltage detection wire 21a1 and the second voltage detection wire 21a2. Note that the first copper wire and the second copper wire can also be electrically joined in a form where the copper wires are joined by the splice terminal 27 having two crimping portions, rather than being wound around and joined.

[0059] The first voltage detection wire 21a1 and the second voltage detection wire 21a2, including the splice terminal 27, are arranged in the wire routing path 24c. Therefore, the splice terminal 27 is arranged together with the plurality of voltage detection wires 21a in the space between a pair of side plates 24b that form the wire routing path 24c. Therefore, even if repeated external forces are applied to the voltage detection wires 21a from the connection socket 22a side and act on the splice terminal 27, the side plates 24b of the wire routing path 24c function to prevent the splice terminal 27 from moving.

[0060] The first voltage detection wire 21a1 between the splice terminal 27 and the electrode joining terminal 25 has a folded excess length 28 folded back in the space between the opposing side plates 24b of the wire routing path 24c.

[0061] 9 shows the length of the folded excess length portion 28. In FIG. 9, the first voltage detection wire 21a1 and the second voltage detection wire 21a2 are arranged between the side plates 24b that form the wire routing path 24c, and the splice terminal 27 is located at the branched portion. The first voltage detection wire 21a1 extending from the splice terminal 27 is folded back midway and extends toward the splice terminal 27 again.

[0062] Furthermore, on the way to the splice terminal 27, the first voltage detection wire 21a1 is pulled outward from a pull-out groove 29 formed in the side plate 24b. The pulled-out first voltage detection wire 21a1 is connected by crimping to the electrode joint terminal 25. The length (L) of the folded excess length portion 28 is from point (P) to point (R) and is determined to be longer than the length (W) of the wire routing path 24c in the width direction (between the opposing side plates). Note that points (P) and (R) are positions corresponding to the positions of the pull-out groove 29.

[0063] The length (L) of the excess portion 28 is from point (P) to point (R) and is stored so that it is longer than the length (W) of the width direction (between the opposing side plates) of the electric wire routing passage 24c.

[0064] Therefore, even if an external tensile force is applied to the voltage detection wire 21a from the connection socket 22a side and the splice terminal 27 moves, the splice terminal 27 is able to move due to the folded excess length portion 28, and by absorbing the external tensile force, the voltage detection wire 21a1 is prevented from being cut.

[0065] Furthermore, since the detected signal can be output with high reliability, a highly reliable battery pack can be provided.Furthermore, by efficiently using the space of the electric wire routing path, a small and highly reliable signal can be output, so a highly reliable battery pack can be provided.

[0066] Although this embodiment focuses on a voltage detection wire, the concept of the present invention can also be applied to other detection wires, such as a temperature detection wire for detecting the temperature of a unit battery. Therefore, voltage detection wires and temperature detection wires can be generalized and referred to as "status detection wires." Furthermore, electrode junction terminals connected to bus bars and temperature detection terminals connected to thermistors can also be considered as status detection terminals.

[0067] In addition, in this embodiment, splice terminals are used at the branching portions, but other connection methods can also be used depending on the purpose.

[0068] As described above, the present invention is characterized in that it comprises a status detection electric wire including a plurality of stacked unit batteries, a first status detection electric wire starting from a status detection terminal for detecting the status of each unit battery, a second status detection electric wire connected to the first status detection electric wire so as to branch midway, and a splice terminal crimped to the connection portion of the first status detection electric wire and the second status detection electric wire, the status detection electric wire including the splice terminal being arranged in a wire routing path of a wire storage box, and a folded excess portion being formed in the first status detection electric wire between the status detection terminal and the splice terminal.

[0069] With this, since the splice terminal is arranged in the wire routing path, movement of the splice terminal is suppressed, and further, since a folded excess length portion is formed, it is possible to prevent breakage even if excessive tensile load or repeated load is applied.

[0070] Further, for example, the battery pack may include a battery group in which unit batteries are stacked so that the positive electrode terminals or the negative electrode terminals face one side, and a wire housing box having a status detection wire for detecting the voltage of the unit batteries and a wire routing path for storing the plurality of status detection wires, wherein the status detection wire is connected to a status detection terminal for detecting the status of one unit battery and includes a first status detection wire connected to a first output part, a branch part formed midway on the first status detection wire, and a second status detection wire branched from the branch part and connected to the second output part, and the plurality of status detection wires include a status detection wire having a folded excess part formed between the status detection terminal and the branch part of the first status detection wire, and the wire routing path extends along a first direction in which the unit batteries are stacked, and the wire routing path stores the first status detection wire, the second status detection wire, the branch part, and the excess part.

[0071] This allows the detected signal to be output with high reliability, making it possible to provide a highly reliable battery pack. Since the multiple state detection lines are housed in the housing space of the electric wire routing path, it is possible to provide a space-saving battery pack.

[0072] In terms of space efficiency, it is preferable that the electrode terminal be formed farther from the end of the unit battery than the positive electrode terminal or the negative electrode terminal in the second direction passing through the positive electrode terminal and the negative electrode terminal of the unit battery.

[0073] The first state detection electric wire, the second state detection electric wire, the branch portion, and the extra length portion may be arranged not only inside the electric wire routing path, but also outside the electric wire routing path.

[0074] Alternatively, the state detection electric wire may have a third state detection electric wire without a branch portion.The electric wire routing path is characterized in that the third state detection electric wire has a surplus portion having a length (L) shorter than that of the first state detection electric wire, or has a third state detection electric wire without a surplus portion.

[0075] This allows for efficient use of the space for the electric wire routing, resulting in a compact and highly reliable signal output, making it possible to provide a highly reliable battery pack.

[0076] Also, for example, the unit battery has a gas exhaust valve that opens when the internal battery pressure reaches a predetermined value, the wire storage box has an opening facing the gas exhaust valve along the first direction, and the wire routing path has multiple paths that are formed along the first direction and arranged on both sides of the opening.

[0077] This allows reliable measurement of the state of the state detection line even when the gas exhaust valve is open.

[0078] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made without departing from the spirit of the present invention as defined in the claims. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0079] 10... battery pack, 11... housing, 12... battery group, 13... unit battery, 14... cell holder, 15... end plate, 16... side plate, 17... bus bar case, 18... bus bar cover, 20... wire pull-out tube, 21a, 21a1, 21a2... voltage detection wire, 22a... connection socket, 23... bus bar, 24... wire storage box (harness case), 24a... upper plate, 24b... side plate, 24c... wire routing path (harness storage section), 25... electrode junction terminal, 26... wire holder, 27... splice terminal, 28... folded excess length portion, 29... pull-out groove, 30... opening (through hole), 32 (+)... positive electrode terminal, 32 (-)... negative electrode terminal, 33... gas release valve.

Claims

1. A battery pack comprising: a plurality of stacked unit batteries; a first status detection wire having a status detection terminal for detecting the status of each of the unit batteries; and a second status detection wire branching from a branch portion formed midway on the first status detection wire; wherein the plurality of status detection wires including the branch portion are arranged in a wire routing path of a wire storage box; and further, a folded-back excess portion is formed on the first status detection wire between the status detection terminal and the branch portion.

2. The battery pack according to claim 1, wherein the unit batteries have positive and negative electrode terminals, and the unit batteries are stacked so that the positive or negative electrode terminal faces one side; and a wire housing box having the status detection wires for detecting the status of the unit batteries and the wire routing path for accommodating a plurality of the status detection wires, wherein the status detection wires are connected to the status detection terminal for detecting the status of one of the unit batteries and include the first status detection wire connected to a first output part, the branch part formed midway on the first status detection wire, and the second status detection wire branched from the branch part and connected to a second output part; and the plurality of status detection wires include the status detection wire having the folded excess length formed between the status detection terminal and the branch part of the first status detection wire, and the wire routing path extends along a first direction in which the unit batteries are stacked; The battery pack, wherein the first state detection wire, the second state detection wire, the branch portion, and the folded excess length portion are housed in the wire routing path.

3. The battery pack according to claim 1, wherein the state detection wire is a voltage detection wire.

4. A battery pack according to claim 3, wherein the wire routing path of the wire storage box is a storage space surrounded by an upper plate of the wire storage box and a pair of side plates connected to the upper plate, the first voltage detection wire, the second voltage detection wire, and the branch portion are stored in the storage space, and the length (L) of the folded excess portion is set to be longer than the length (W) of the pair of side plates facing each other.

5. A battery pack having a plurality of stacked unit batteries, bus bars provided on each of the unit batteries, a wire storage box arranged in the stacking direction of the unit batteries, a wire routing path formed in the wire storage box, and a voltage detection wire arranged in the wire routing path and connected to an electrode connection terminal welded to the bus bar, wherein the voltage detection wire comprises at least a first voltage detection wire starting from the electrode connection terminal, a second voltage detection wire connected to the first voltage detection wire so as to branch midway, and a branch portion crimped to the connection portion of the first voltage detection wire and the second voltage detection wire, wherein the voltage detection wire including the branch portion is arranged in the wire routing path of the wire storage box, and a folded-back excess length portion is formed in the first voltage detection wire between the electrode connection terminal and the branch portion.

6. A battery pack according to claim 5, wherein the wire routing path of the wire storage box is a storage space surrounded by an upper plate of the wire storage box and a pair of side plates connected to the upper plate, the first voltage detection wire, the second voltage detection wire, and the branch portion are stored in the storage space, and the length of the folded excess portion is determined to be longer than the opposing length of the pair of side plates.

7. The battery pack according to claim 2, wherein the state detection wire is a voltage detection wire.

8. A battery pack according to claim 2, wherein the state detection wire comprises a third state detection wire that does not have the branch portion, and the wire routing path accommodates the folded excess length that is shorter than the folded excess length of the first state detection wire, or the third state detection wire does not accommodate the folded excess length.

9. A battery pack as claimed in claim 2, wherein the unit battery has a gas release valve that opens when the internal battery pressure reaches a predetermined value, the wire storage box has an opening facing the gas release valve along the first direction, and the wire routing path is provided in plurality, is formed along the first direction and is arranged on both sides of the opening.

10. A battery pack according to claim 2, wherein the electric wire routing path is formed farther from the end of the unit battery than the positive electrode terminal or the negative electrode terminal in a second direction passing through the positive electrode terminal and the negative electrode terminal of the unit battery.

11. A battery pack comprising: a plurality of stacked unit batteries; a first status detection wire originating from a status detection terminal for detecting the status of each of the unit batteries; a second status detection wire connected to the first status detection wire so as to branch midway; and a splice terminal crimped to the connection portion of the first status detection wire and the second status detection wire; wherein the status detection wire including the splice terminal is arranged in a wire routing path of a wire storage box; and further, a folded excess portion is formed in the first status detection wire between the status detection terminal and the splice terminal.

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