Battery pack

Abstract

To improve uniformity of cooling of a battery module.SOLUTION: The battery pack 10 includes a battery module 100 and a flow path 300 through which a refrigerant for cooling the battery module 100 flows. The flow path 300 includes a fourth cooling-flow path 100c and a fifth cooling-flow path 100d that at least partially overlap the third battery module 310d and the fourth battery module 310e, and a sixth cooling-flow path 310e that branches off from the fifth cooling-flow path 310f. The flow path length of the fourth cooling water flow path 310d is longer than the flow path length of the fifth cooling water flow path 310e.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] In recent years, various types of battery packs have been developed, and some battery packs include a battery module and a flow path for flowing a coolant for cooling the battery module.

[0003] Patent Document 1 describes a battery pack. The battery pack includes a plurality of battery cells and a press plate that overlaps the plurality of battery cells. Grooves are formed in the press plate. The grooves form cooling paths.

[0004] Patent Document 2 describes a cold plate for a battery module, which includes a liquid supply assembly, a liquid cooling module that fits the battery module, and a liquid discharge assembly. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Chinese Utility Model No. 215418404 [Patent Document 2] Chinese Patent Application Publication No. 111668574 Summary of the Invention [Problem to be solved by the invention]

[0006] As described in Patent Documents 1 and 2, battery modules may be cooled by cooling channels. When cooling battery modules by cooling channels, it may be necessary to improve the uniformity of cooling of the battery modules.

[0007] One object of the present invention is to improve the uniformity of cooling of a battery module. Other objects of the present invention will become apparent from the description herein. [Means for solving the problem]

[0008] One aspect of the present invention is as follows. 1. A battery module; a flow path for flowing a refrigerant for cooling the battery module; Equipped with the flow path includes a plurality of cooling flow paths at least partially overlapping with the battery module, and a branch flow path branching from at least one of the cooling flow paths; A battery pack, wherein the flow path length of at least one other of the cooling flow paths is longer than the flow path length of the at least one other of the cooling flow paths. 2. The battery module has a plurality of battery cells arranged in a predetermined direction, 1. The battery pack according to claim 1, wherein the plurality of cooling channels extend at least partially in the predetermined direction. 3. The battery pack described in 2., wherein the plurality of cooling flow paths are configured to allow the refrigerant to flow from portions of the plurality of cooling flow paths that overlap with approximately the center portions of the battery modules in a direction perpendicular to the predetermined direction. 4. The battery pack according to 2. or 3., wherein a plurality of the battery modules are arranged in the predetermined direction. 5. The battery pack according to any one of 1. to 4., wherein the branch flow path at least partially overlaps a heat-generating element different from the battery module. 6. A battery module; a flow path for flowing a refrigerant for cooling the battery module; Equipped with The flow path includes a plurality of cooling flow paths at least partially overlapping with the battery modules, and a communication flow path communicating with at least one of the cooling flow paths. 7. The battery module has a plurality of battery cells arranged in a predetermined direction, 6. The battery pack according to claim 6, wherein the plurality of cooling channels extend at least partially in the predetermined direction. 8. The battery pack described in 7., wherein the plurality of cooling flow paths are configured to allow the refrigerant to flow from portions of the plurality of cooling flow paths that overlap with approximately the center portions of the battery modules in a direction perpendicular to the predetermined direction. 9. The battery pack according to claim 7 or 8, wherein a plurality of the battery modules are arranged in the predetermined direction. 10. The battery pack according to any one of 6 to 9, wherein the communication flow path at least partially overlaps a heat-generating element different from the battery module. 11. A battery module; a flow path for flowing a refrigerant for cooling the battery module; Equipped with the flow path has a first region into which the refrigerant flows at a predetermined first flow rate, a second region located downstream of the first region and into which the refrigerant flows at a second flow rate less than the first flow rate from a region different from the first region, a third region branched from the first region and into which the refrigerant flows at a third flow rate less than both the first flow rate and the second flow rate, and a fourth region located downstream of the third region, A battery pack, wherein a portion of the flow path between the first region and the second region and a portion of the flow path between the third region and the fourth region are fluidly connected to each other. 12. The battery pack according to claim 11, wherein at least some corners of the flow path from the first region to the fourth region are rounded. 13. The battery pack according to claim 11 or 12, wherein the first region and the second region are regions into which the coolant flows from a region that at least partially overlaps with the battery module. [Effects of the Invention]

[0009] According to the above aspect of the present invention, it is possible to improve the uniformity of cooling of the battery module. [Brief explanation of the drawings]

[0010] [Figure 1]FIG. 1 is a perspective view of a battery pack according to an embodiment. [Figure 2] FIG. 2 is a plan view of the battery pack according to the embodiment with the side frame and the upper case removed. [Figure 3] FIG. 10 is a plan view of the lower plate according to the embodiment with the upper cooling plate removed. [Figure 4] FIG. 4 is an enlarged plan view of a peripheral portion of a communication flow path of a flow path according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, similar components are designated by similar reference numerals, and the description thereof will be omitted as appropriate.

[0012] Fig. 1 is a perspective view of a battery pack 10 according to an embodiment. Fig. 2 is a plan view of the battery pack 10 according to an embodiment with a side frame 220 and an upper case 230 removed. Fig. 3 is a plan view of a lower plate 210 according to an embodiment with an upper cooling plate 214 removed.

[0013] In the embodiment, the battery pack 10 is mounted on an automobile. Specifically, the battery pack 10 is mounted between the front and rear wheels of the automobile. Unless otherwise specified, the following description will be given assuming that the battery pack 10 is mounted on an automobile. However, the battery pack 10 can also be used for purposes other than automobiles.

[0014] For the purpose of explanation, the X, Y, and Z directions are shown in each figure. The X direction indicates the front-to-rear direction of the battery pack 10. The Y direction is one of the perpendicular directions. The Y direction indicates the left-to-right direction of the battery pack 10. The Z direction is perpendicular to both the X and Y directions. The Z direction indicates the up-to-down direction of the battery pack 10. The arrows pointing to the X direction, the Y direction, and the Z direction indicate the front, left, and up directions of the battery pack 10, respectively. In Figures 2 and 3, the white circle with a black dot indicating the Z direction indicates that the arrow pointing to the Z direction extends from the back of the page to the front. The relationship between the X, Y, and Z directions and the front-to-rear, left-to-right, and up-to-down directions of the battery pack 10 is not limited to this example.

[0015] In the embodiment, the front-rear direction, left-right direction, and up-down direction of the battery pack 10 are determined by the vehicle in which the battery pack 10 is mounted. The X direction, Y direction, and Z direction respectively indicate the front-rear direction, left-right direction, and up-down direction of the vehicle. The arrow pointing to the X direction, the arrow pointing to the Y direction, and the arrow pointing to the Z direction respectively indicate the front, left, and up directions of the vehicle. However, the relationship between the front-rear direction, left-right direction, and up-down direction of the battery pack 10 and the front-rear direction, left-right, and up-down directions of the vehicle is not limited to this example.

[0016] Hereinafter, as needed, the side indicated by the arrow indicating the X direction will be referred to as the +X side, and the side opposite the side indicated by the arrow indicating the X direction will be referred to as the -X side. Hereinafter, as needed, the side indicated by the arrow indicating the Y direction will be referred to as the +Y side, and the side opposite the side indicated by the arrow indicating the Y direction will be referred to as the -Y side. Hereinafter, as needed, the side indicated by the arrow indicating the Z direction will be referred to as the +Z side, and the side opposite the side indicated by the arrow indicating the Z direction will be referred to as the -Z side.

[0017] A battery pack 10 according to an embodiment will be described with reference to FIGS.

[0018] As shown in FIGS. 1 to 3, a battery pack 10 according to the embodiment includes a plurality of battery modules 100, a junction box 110, and a pack housing 200. The battery pack 10 includes a plurality of battery modules 100, a junction box 110, and a pack housing 200. As shown in FIG.

[0019] 2, the plurality of battery modules 100 according to the embodiment include a first battery module 100a, a second battery module 100b, a third battery module 100c, a fourth battery module 100d, and a fifth battery module 100e. When viewed from the Z direction, the first battery module 100a, the second battery module 100b, the third battery module 100c, and the fourth battery module 100d are arranged in two rows and two columns in the X and Y directions, respectively. When viewed from the Z direction, the first battery module 100a, the second battery module 100b, the third battery module 100c, and the fourth battery module 100d are located on the +X side and the -Y side, the +X side and the +Y side, the -X side and the -Y side, and the -X side and the +Y side, respectively, of the center of the area in which the first battery module 100a, the second battery module 100b, the third battery module 100c, and the fourth battery module 100d are arranged. The fifth battery module 100e is located on the -X side relative to the third battery module 100c and the fourth battery module 100d.

[0020] As shown in FIG. 2, the first battery module 100a has a plurality of battery cells 102 and a module housing 104. In FIG. 2, for the sake of explanation, the plurality of battery cells 102 of the first battery module 100a are shown with dashed lines. Each battery cell 102 of the first battery module 100a has a substantially rectangular parallelepiped shape with a pair of long sides substantially parallel to the X direction and a pair of short sides substantially parallel to the Z direction, and a height substantially parallel to the Y direction. The plurality of battery cells 102 of the first battery module 100a are aligned in the Y direction. The plurality of battery cells 102 of the first battery module 100a are electrically connected to each other in series, in parallel, or in a combination of series and parallel. The module housing 104 of the first battery module 100a accommodates the plurality of battery cells 102 of the first battery module 100a. In the example shown in FIG. 2, the module housing 104 of the first battery module 100a has a substantially rectangular parallelepiped shape with a base that is substantially rectangular, with a pair of sides substantially parallel to the X direction and another pair of sides substantially parallel to the Y direction, and a height that is substantially parallel to the Z direction.

[0021] Similar to the first battery module 100a, the second battery module 100b, the third battery module 100c, and the fourth battery module 100d also have a plurality of battery cells 102 and a module housing 104. The configurations of the plurality of battery cells 102 and the module housing 104 of each of the second battery module 100b, the third battery module 100c, and the fourth battery module 100d are the same as the configurations of the plurality of battery cells 102 and the module housing 104 of the first battery module 100a.

[0022] Similar to the first battery module 100a, the fifth battery module 100e has a plurality of battery cells 102 and a module housing 104. When viewed from the Z direction, the plurality of battery cells 102 of the fifth battery module 100e may be aligned in the X direction. The volume of the module housing 104 of the fifth battery module 100e is less than the volume of the module housing 104 of each of the first battery module 100a, the second battery module 100b, the third battery module 100c, and the fourth battery module 100d. In the example shown in FIG. 2, the module housing 104 of the fifth battery module 100e has a substantially rectangular parallelepiped shape with a pair of short sides substantially parallel to the X direction and a pair of long sides substantially parallel to the Y direction, a substantially rectangular bottom surface, and a height substantially parallel to the Z direction.

[0023] The junction box 110 is located on the +X side relative to the first battery module 100a and the second battery module 100b. The batteries formed by the multiple battery cells 102 of each battery module 100 are electrically connected to each other via conductors such as bus bars (not shown) arranged outside each battery module 100. The junction box 110 is electrically connected to a circuit formed by the multiple battery cells 102 of the multiple battery modules 100.

[0024] The number and arrangement of the battery modules 100 in the battery pack 10 are not limited to the example shown in Fig. 2. For example, the fifth battery module 100e does not have to be provided. The battery pack 10 may include only one battery module 100.

[0025] The pack housing 200 houses a plurality of battery modules 100 and a junction box 110. As shown in FIG.

[0026] As shown in FIGS. 2 and 3 , the lower plate 210 includes a lower cooling plate 212 and an upper cooling plate 214. The lower cooling plate 212 and the upper cooling plate 214 are arranged substantially perpendicular to the Z direction. The lower cooling plate 212 and the upper cooling plate 214 overlap each other in the Z direction, with the upper cooling plate 214 arranged on the +Z side of the lower cooling plate 212. As shown in FIGS. 2 and 3 , the lower cooling plate 212 and the upper cooling plate 214 have substantially the same shape when viewed from the Z direction. In the example shown in FIGS. 2 and 3 , the lower cooling plate 212 and the upper cooling plate 214 have a substantially rectangular shape with a pair of long sides substantially parallel to the X direction and a pair of short sides substantially parallel to the Y direction, and with the four corners cut off, when viewed from the Z direction. In other words, the lower cooling plate 212 and the upper cooling plate 214 have a substantially octagonal shape when viewed from the Z direction. The shapes of the lower cooling plate 212 and the upper cooling plate 214 are not limited to the examples shown in FIGS.

[0027] The side frame 220 is disposed on the outer periphery in the Z direction on the +Z side surface of the upper cooling plate 214. When viewed from the Z direction, the side frame 220 surrounds the plurality of battery modules 100 and the battery modules 100 in the Z direction.

[0028] The upper case 230 is located on the +Z side with respect to the multiple battery modules 100 and the junction box 110. The upper case 230 is disposed approximately perpendicular to the Z direction. When viewed from the Z direction, the lower plate 210 and the upper case 230 have approximately the same shape. Portions of the +Z side surface of the side frame 220 and the -Z side surface of the upper case 230 that overlap with the side frame 220 in the Z direction are attached to each other. The lower plate 210, the side frame 220, and the upper case 230 define an accommodation space that accommodates the multiple battery modules 100 and the junction box 110, with the +Z side surface of the side frame 220 and the -Z side surface of the upper case 230 that overlap with the side frame 220 in the Z direction being attached to each other.

[0029] 3, the lower plate 210 defines a flow path 300. In the embodiment, the flow path 300 is defined by a recess provided on the +Z side surface of the lower cooling plate 212 and a portion of the upper cooling plate 214 that covers the recess. However, the structure of the flow path 300 is not limited to this example. For example, piping for defining the flow path 300 may be provided separately from the lower plate 210.

[0030] As shown in FIG. 3, the flow path 300 has an inlet portion 302, an outlet portion 304, a first branch introduction flow path 306a, a second branch introduction flow path 306b, a third branch introduction flow path 306c, a first communicating introduction flow path 306d, a second communicating introduction flow path 306e, a first upstream exhaust flow path 308a1, a first downstream exhaust flow path 308a2, a second upstream exhaust flow path 308b1, a second downstream exhaust flow path 308b2, a communicating flow path 308c, a communicating exhaust flow path 308d, and multiple cooling flow paths 310.

[0031] The flow path 300 is a flow path for flowing a refrigerant for cooling the multiple battery modules 100 and the junction box 110 from the inlet portion 302 to the outlet portion 304. The refrigerant may be a liquid such as water, but is not limited to this. In the example shown in Fig. 3, when viewed from the Z direction, the inlet portion 302 is located at a corner on the +X side and the -Y side of the lower plate 210. In the example shown in Fig. 3, when viewed from the Z direction, the outlet portion 304 is located at a corner on the +X side and the +Y side of the lower plate 210.

[0032] As shown in FIG. 3 , the first branch introduction channel 306a, the second branch introduction channel 306b, and the third branch introduction channel 306c are branched off from one another, with one end of each of the first branch introduction channel 306a, the second branch introduction channel 306b, and the third branch introduction channel 306c fluidly connected to the inlet portion 302. When viewed from the Z direction, the first branch introduction channel 306a, the second branch introduction channel 306b, and the third branch introduction channel 306c extend in the X direction, excluding the periphery of the inlet portion 302 in the Z direction. In the example shown in FIG. 3 , the portion of the first branch introduction channel 306a extending in the X direction, the portion of the second branch introduction channel 306b extending in the X direction, and the portion of the third branch introduction channel 306c extending in the X direction are aligned in this order from the +Y side to the −Y side. The cross sections perpendicular to the channel lengths of the first branch introduction channel 306a, the second branch introduction channel 306b, and the third branch introduction channel 306c are substantially equal. Therefore, the flow rates of the refrigerant in the first branch introduction flow path 306a, the second branch introduction flow path 306b, and the third branch introduction flow path 306c are approximately equal.

[0033] As shown in FIG. 3 , when viewed from the Z direction, the first upstream discharge flow path 308a1 extends in the X direction. When viewed from the Z direction, the first downstream discharge flow path 308a2 extends in the X direction except for the periphery of the outlet portion 304 in the Z direction. The first upstream discharge flow path 308a1 and the first downstream discharge flow path 308a2 are aligned in the X direction with the +X side end of the first upstream discharge flow path 308a1 and the -X side end of the first downstream discharge flow path 308a2 fluidly connected to each other. The first upstream discharge flow path 308a1 and the first downstream discharge flow path 308a2 are located upstream and downstream of the flow path 300 with respect to the +X side end of the first upstream discharge flow path 308a1 and the -X side end of the first downstream discharge flow path 308a2, respectively. The cross-sectional areas perpendicular to the flow path lengths of the first upstream discharge flow path 308a1 and the first downstream discharge flow path 308a2 are approximately equal.

[0034] As shown in FIG. 3 , when viewed from the Z direction, the second upstream discharge flow path 308b1 extends in the X direction. When viewed from the Z direction, the second downstream discharge flow path 308b2 extends in the X direction except for the periphery around the outlet portion 304 in the Z direction. The second upstream discharge flow path 308b1 and the second downstream discharge flow path 308b2 are aligned in the X direction with the +X side end of the second upstream discharge flow path 308b1 and the -X side end of the second downstream discharge flow path 308b2 fluidly connected to each other. The second upstream discharge flow path 308b1 and the second downstream discharge flow path 308b2 are located upstream and downstream of the flow path 300, respectively, with respect to the +X side end of the second upstream discharge flow path 308b1 and the -X side end of the second downstream discharge flow path 308b2. The cross-sectional areas perpendicular to the flow path lengths of the second upstream discharge flow path 308b1 and the second downstream discharge flow path 308b2 are approximately equal.

[0035] The first upstream discharge flow path 308a1 and the second upstream discharge flow path 308b1 branch off from each other, and the first downstream discharge flow path 308a2 and the second downstream discharge flow path 308b2 branch off from each other. A portion of the flow path 300 between the +X side end of the first upstream discharge flow path 308a1 and the -X side end of the first downstream discharge flow path 308a2 and a portion of the flow path 300 between the +X side end of the second upstream discharge flow path 308b1 and the -X side end of the second downstream discharge flow path 308b2 are fluidly connected to each other via a communication flow path 308c. When viewed from the Z direction, the first upstream discharge flow path 308a1 and the second upstream discharge flow path 308b1 are located on the -Y side and the +Y side, respectively, of the region between the first upstream discharge flow path 308a1 and the second upstream discharge flow path 308b1. When viewed from the Z direction, the first downstream discharge flow path 308a2 and the second downstream discharge flow path 308b2 are located on the -Y side and +Y side, respectively, of the region between the second upstream discharge flow path 308b1 and the second downstream discharge flow path 308b2.

[0036] 3, the plurality of cooling channels 310 form a plurality of cooling zones 312 of the lower plate 210. As shown in FIG. 3, when viewed in the Z direction, each cooling channel 310 is at least partially serpentine, with each cooling zone 312 being occupied substantially entirely by the cooling channel 310. The plurality of cooling channels 310 includes a first cooling channel 310a, a second cooling channel 310b, a third cooling channel 310c, a fourth cooling channel 310d, a fifth cooling channel 310e, and a sixth cooling channel 310f. The first cooling flow path 310a, the second cooling flow path 310b, the third cooling flow path 310c, the fourth cooling flow path 310d, the fifth cooling flow path 310e, and the sixth cooling flow path 310f form the first cooling region 312a, the second cooling region 312b, the third cooling region 312c, the fourth cooling region 312d, the fifth cooling region 312e, and the sixth cooling region 312f, respectively.

[0037] The first cooling channel 310a, the second cooling channel 310b, the third cooling channel 310c, the first cooling region 312a, the second cooling region 312b, and the third cooling region 312c will be described with reference to FIGS.

[0038] As shown in FIG. 3, the first cooling region 312a and the second cooling region 312b are aligned in the X direction to form a single cooling region. The first cooling region 312a and the second cooling region 312b are located on the +X side and the -X side, respectively, of the boundary between the first cooling region 312a and the second cooling region 312b. The area of ​​the first cooling region 312a perpendicular to the Z direction and the area of ​​the second cooling region 312b perpendicular to the Z direction are substantially equal. As shown in FIG. 3, when viewed from the Z direction, the first cooling region 312a has a substantially rectangular shape with a pair of short sides substantially parallel to the X direction and a pair of long sides substantially parallel to the Y direction. As shown in FIG. 3, when viewed from the Z direction, the second cooling region 312b has a substantially rectangular shape with a pair of short sides substantially parallel to the X direction and a pair of long sides substantially parallel to the Y direction. The shapes of the first cooling region 312a and the second cooling region 312b are not limited to the example shown in FIG. 3.

[0039] As shown in Fig. 3, when viewed from the Z direction, the third cooling region 312c is located away from the first cooling region 312a toward the +X side. As shown in Fig. 3, when viewed from the Z direction, the third cooling region 312c has a substantially rectangular shape having a pair of short sides substantially parallel to the X direction and a pair of long sides substantially parallel to the Y direction. The shape of the third cooling region 312c is not limited to the example shown in Fig. 3.

[0040] The first cooling flow path 310a and the first branch introduction flow path 306a are in communication with each other, with one end of the first cooling region 312a of the first cooling flow path 310a on the -Y side fluidly connected to the other end of the first branch introduction flow path 306a opposite the inlet portion 302. The first cooling flow path 310a and the third cooling flow path 310c are in communication with each other, with the other end of the first cooling region 312a of the first cooling flow path 310a on the +Y side fluidly connected to one end of the third cooling region 312c of the third cooling flow path 310c on the -X side fluidly connected to each other. The first cooling flow path 310a is configured to allow the refrigerant to flow from one end of the first cooling region 312a of the first cooling flow path 310a on the -Y side to the other end of the first cooling region 312a of the first cooling flow path 310a on the +Y side. In other words, the inlet and outlet of the refrigerant of the first cooling flow path 310a are located at one end of the first cooling region 312a of the first cooling flow path 310a on the -Y side and the other end of the first cooling region 312a of the first cooling flow path 310a on the +Y side, respectively. In the example shown in Fig. 3, the first cooling flow path 310a is folded back alternately on both sides of the first cooling region 312a in the Y direction. The shape of the first cooling flow path 310a is not limited to the example shown in Fig. 3.

[0041] Hereinafter, unless otherwise specified, the inlet of the first cooling flow path 310a refers to one end on the -Y side of the first cooling region 312a of the first cooling flow path 310a, and the outlet of the first cooling flow path 310a refers to the other end on the +Y side of the first cooling region 312a of the first cooling flow path 310a.

[0042] The second cooling flow path 310b and the first branch inlet flow path 306a are in communication with each other, with one end of the second cooling region 312b of the second cooling flow path 310b on the -Y side fluidly connected to the other end of the first branch inlet flow path 306a opposite the inlet portion 302. The second cooling flow path 310b and the first downstream discharge flow path 308a2 are in communication with the other end of the second cooling region 312b of the second cooling flow path 310b on the +Y side fluidly connected to the -X side end of the first downstream discharge flow path 308a2. The second cooling flow path 310b is configured to flow the refrigerant from one end of the second cooling region 312b of the second cooling flow path 310b on the -Y side to the other end of the second cooling region 312b of the second cooling flow path 310b on the +Y side. In other words, the inlet and outlet of the refrigerant of the second cooling flow path 310b are located at one end of the second cooling region 312b of the second cooling flow path 310b on the -Y side and the other end of the second cooling region 312b of the second cooling flow path 310b on the +Y side, respectively. In the example shown in Fig. 3, the second cooling flow path 310b is folded back alternately on both sides of the second cooling region 312b in the Y direction. The shape of the second cooling flow path 310b is not limited to the example shown in Fig. 3.

[0043] Hereinafter, unless otherwise specified, the inlet of the second cooling flow path 310b refers to one end on the -Y side of the second cooling region 312b of the second cooling flow path 310b, and the outlet of the second cooling region 312b refers to the other end on the +Y side of the second cooling region 312b of the second cooling flow path 310b.

[0044] As shown in FIGS. 2 and 3 , the first cooling region 312a and the second cooling region 312b at least partially overlap the first battery module 100a and the second battery module 100b in the Z direction. The −Z side surface of the module housing 104 of the first battery module 100a and the +Z side surface of the lower plate 210 at the portion overlapping the first battery module 100a in the Z direction are bonded to each other via a thermally conductive material such as a thermally conductive filler. The −Z side surface of the module housing 104 of the second battery module 100b and the +Z side surface of the lower plate 210 at the portion overlapping the second battery module 100b in the Z direction are bonded to each other via a thermally conductive material such as a thermally conductive filler. The first battery module 100a and the second battery module 100b are heat-generating elements. In this embodiment, the first battery module 100a and the second battery module 100b can be cooled by the first cooling region 312a and the second cooling region 312b.

[0045] As shown in Fig. 3, the first cooling flow path 310a at least partially extends in the Y direction, excluding the turning backs on both sides of the first cooling region 312a of the first cooling flow path 310a in the Y direction. As shown in Fig. 3, the second cooling flow path 310b at least partially extends in the Y direction, excluding the turning backs on both sides of the second cooling region 312b of the second cooling flow path 310b in the Y direction. As described above, in each of the first battery module 100a and the second battery module 100b, the multiple battery cells 102 are aligned in the Y direction. Therefore, when viewed from the Z direction, the first cooling flow path 310a and the second cooling flow path 310b at least partially extend in the alignment direction of the multiple battery cells 102 of the first battery module 100a and the second battery module 100b. Therefore, the uniformity of cooling of the multiple battery cells 102 in each of the first battery module 100a and the second battery module 100b can be improved compared to when the first cooling flow path 310a and the second cooling flow path 310b extend in a direction perpendicular to the arrangement direction of the multiple battery cells 102 in the first battery module 100a and the second battery module 100b when viewed from the Z direction.

[0046] 2 and 3, the inlets of the first cooling flow path 310a and the second cooling flow path 310b overlap in the Z direction with the approximate center in the X direction of the -Y side portion of the first battery module 100a. The multiple battery cells 102 of each of the first battery module 100a and the second battery module 100b tend to generate heat more easily in the approximate center in the X direction of each battery cell 102 than at both ends in the X direction of each battery cell 102. Therefore, the uniformity of cooling of the multiple battery cells 102 of each of the first battery module 100a and the second battery module 100b can be improved compared to when the inlets of the first cooling flow path 310a and the second cooling flow path 310b are positioned offset in the X direction from the approximate center in the X direction of the first battery module 100a.

[0047] The third cooling flow path 310c is a communicating flow path that communicates with the first cooling flow path 310a, with one end of the third cooling region 312c of the third cooling flow path 310c on the -X side fluidly connected to the other end of the first cooling region 312a of the first cooling flow path 310a on the +Y side, and with the other end of the third cooling region 312c of the third cooling flow path 310c on the +X side fluidly connected to the outlet portion 304. In the example shown in FIG. 3, the third cooling flow path 310c is folded back at the end of the third cooling region 312c on the -Y side. The shape of the third cooling flow path 310c is not limited to the example shown in FIG. 3.

[0048] 2 and 3, the third cooling region 312c and the junction box 110 at least partially overlap each other in the Z direction. The junction box 110 is a heat-generating element. In the embodiment, the junction box 110 can be cooled by the third cooling region 312c.

[0049] In this embodiment, the flow path length of first cooling flow path 310a and the flow path length of second cooling flow path 310b are approximately equal, and the cross-sectional area perpendicular to the flow path length of first cooling flow path 310a and the cross-sectional area perpendicular to the flow path length of second cooling flow path 310b are approximately equal. The flow path length from inlet portion 302 to the inlet of first cooling flow path 310a and the flow path length from inlet portion 302 to the inlet of second cooling flow path 310b are approximately equal. Meanwhile, the shortest distance from the outlet of first cooling flow path 310a to outlet portion 304 is shorter than the shortest distance from the outlet of second cooling flow path 310b to outlet portion 304. Therefore, if the first cooling flow path 310a were connected to the first downstream exhaust flow path 308a2 without communicating with the third cooling flow path 310c, the flow path length from the inlet portion 302 to the outlet portion 304 via the first cooling flow path 310a would be shorter than the flow path length from the inlet portion 302 to the outlet portion 304 via the second cooling flow path 310b, and the cooling capacity of the second cooling region 312b would be less than the cooling capacity of the first cooling region 312a. However, in this embodiment, the first cooling flow path 310a is connected to the third cooling flow path 310c without communicating with the first downstream exhaust flow path 308a2. Therefore, the flow path length from the inlet portion 302 to the outlet portion 304 via the first cooling flow path 310a can be longer than in the case where the first cooling flow path 310a is connected to the first downstream exhaust flow path 308a2 without communicating with the third cooling flow path 310c. Therefore, compared to when the first cooling flow path 310a is not connected to the third cooling flow path 310c but is connected to the first downstream discharge flow path 308a2, the cooling capacity of the first cooling flow path 310a can be made closer to the cooling capacity of the second cooling flow path 310b, and the uniformity of cooling of the first battery module 100a and the second battery module 100b by the first cooling area 312a and the second cooling area 312b can be improved.

[0050] From the description of the embodiment, when multiple cooling channels corresponding to the first cooling channel 310a and the second cooling channel 310b at least partially overlap with the battery module 100, by communicating at least one cooling channel with the communicating channel corresponding to the third cooling channel 310c, it is possible to improve the uniformity of cooling of the battery module 100 by the multiple cooling channels. For example, when the channel lengths from the inlet portion 302 to the outlet portion 304 via the cooling channels are different in the multiple cooling channels in the absence of a communicating channel, it is possible to improve the uniformity of cooling of the battery module 100 by the multiple cooling channels by communicating a cooling channel with a shorter channel length from the inlet portion 302 to the outlet portion 304 via the cooling channels with the communicating channel.

[0051] In the embodiment, the third cooling channel 310c for cooling the junction box 110 is a communicating channel that communicates with the first cooling channel 310a. However, the communicating channel does not have to be a cooling channel for cooling a heat-generating element such as the junction box 110, and may simply be a channel that communicates with the first cooling channel 310a. Alternatively, the communicating channel may at least partially overlap in the Z direction with a heat-generating element other than the junction box 110, such as the battery module 100.

[0052] The first cooling channel 310a and the second cooling channel 310b may have various shapes as long as the shape improves the cooling uniformity of the first cooling region 312a and the second cooling region 312b. For example, even if the first cooling channel 310a is alternately folded back on both sides of the first cooling region 312a in the X direction and the second cooling region 312b is alternately folded back on both sides of the second cooling region 312b in the X direction, the first cooling channel 310a and the third cooling channel 310c are connected to each other, thereby improving the cooling uniformity of the first cooling region 312a and the second cooling region 312b.

[0053] The fourth cooling channel 310d, the fifth cooling channel 310e, the sixth cooling channel 310f, the fourth cooling region 312d, the fifth cooling region 312e, and the sixth cooling region 312f will be described with reference to FIGS.

[0054] As shown in FIG. 3, the fourth cooling region 312d and the fifth cooling region 312e are aligned in the X direction to form an integrated cooling region. The fourth cooling region 312d and the fifth cooling region 312e are located on the +X side and the -X side, respectively, of the boundary between the fourth cooling region 312d and the fifth cooling region 312e. The area of ​​the fourth cooling region 312d perpendicular to the Z direction is larger than the area of ​​the fifth cooling region 312e perpendicular to the Z direction when the partial convex portion on the -X side of the fourth cooling region 312d fits into the partial concave portion on the +X side of the fifth cooling region 312e. As shown in FIG. 3, when viewed from the Z direction, the fourth cooling region 312d has a composite shape in which the convex portion of the fourth cooling region 312d is added to a substantially rectangular shape having a pair of short sides substantially parallel to the X direction and a pair of long sides substantially parallel to the Y direction. As shown in Fig. 3, when viewed from the Z direction, the fifth cooling region 312e has a composite shape obtained by subtracting the recessed portion of the fifth cooling region 312e from a generally rectangular shape having a pair of short sides generally parallel to the X direction and a pair of long sides generally parallel to the Y direction. In the example shown in Fig. 3, when viewed from the Z direction, the protrusions of the fourth cooling region 312d and the recessed portion of the fifth cooling region 312e have a generally quadrangular shape having a pair of sides generally parallel to the X direction and another pair of sides generally parallel to the Y direction. The shapes of the fourth cooling region 312d and the fifth cooling region 312e are not limited to the example shown in Fig. 3.

[0055] As shown in Fig. 3, when viewed from the Z direction, the sixth cooling region 312f is located away from the fifth cooling region 312e toward the -X side. As shown in Fig. 3, when viewed from the Z direction, the fifth cooling region 312e has a substantially rectangular shape having a pair of short sides substantially parallel to the X direction and a pair of long sides substantially parallel to the Y direction. The shape of the sixth cooling region 312f is not limited to the example shown in Fig. 3.

[0056] The fourth cooling flow path 310d and the second branch introduction flow path 306b are in communication with each other, with one end of the fourth cooling region 312d of the fourth cooling flow path 310d on the -Y side fluidly connected to the other end of the second branch introduction flow path 306b opposite the inlet portion 302. The fourth cooling flow path 310d and the first upstream discharge flow path 308a1 are in communication with the other end of the fourth cooling region 312d of the fourth cooling flow path 310d on the +Y side fluidly connected to the +X side end of the first upstream discharge flow path 308a1. The fourth cooling flow path 310d is configured to flow the refrigerant from one end of the fourth cooling region 312d of the fourth cooling flow path 310d on the -Y side to the other end of the fourth cooling region 312d of the fourth cooling flow path 310d on the +Y side. In other words, the inlet and outlet of the refrigerant of the fourth cooling flow path 310d are located at one end of the fourth cooling flow path 310d on the -Y side of the fourth cooling region 312d and the other end of the fourth cooling flow path 310d on the +Y side of the fourth cooling region 312d, respectively. In the example shown in Fig. 3, the fourth cooling flow path 310d is partially bent at a substantially right angle toward the -X side at a partial convex portion on the -X side of the fourth cooling region 312d, and is folded back at the partial convex portion on the -X side of the fourth cooling region 312d and the -Y side of the fourth cooling region 312d. The shape of the fourth cooling flow path 310d is not limited to the example shown in Fig. 3.

[0057] Hereinafter, unless otherwise specified, the inlet of the fourth cooling flow path 310d refers to one end on the -Y side of the fourth cooling region 312d of the fourth cooling flow path 310d, and the outlet of the fourth cooling flow path 310d refers to the other end on the +Y side of the fourth cooling region 312d of the fourth cooling flow path 310d.

[0058] The fifth cooling flow channel 310e and the third branch introduction flow channel 306c are in communication with each other, with one end of the fifth cooling region 312e of the fifth cooling flow channel 310e on the -Y side fluidly connected to the other end of the third branch introduction flow channel 306c opposite the inlet portion 302. The fifth cooling flow channel 310e and the first upstream discharge flow channel 308a1 are in communication with the other end of the fifth cooling region 312e of the fifth cooling flow channel 310e on the +Y side fluidly connected to the -X side end of the first upstream discharge flow channel 308a1. The fifth cooling flow channel 310e is configured to flow a refrigerant from one end of the fifth cooling region 312e of the fifth cooling flow channel 310e on the -Y side to the other end of the fifth cooling region 312e of the fifth cooling flow channel 310e on the +Y side. In other words, the inlet and outlet of the refrigerant of the fifth cooling flow path 310e are located at one end of the fifth cooling region 312e of the fifth cooling flow path 310e on the -Y side and the other end of the fifth cooling flow path 310e on the +Y side of the fifth cooling region 312e, respectively. In the example shown in Fig. 3, the fifth cooling flow path 310e is folded back alternately on both sides of the fifth cooling region 312e in the Y direction. The shape of the fifth cooling flow path 310e is not limited to the example shown in Fig. 3.

[0059] Hereinafter, unless otherwise specified, the inlet of the fifth cooling flow path 310e refers to one end on the -Y side of the fifth cooling region 312e of the fifth cooling flow path 310e, and the outlet of the fifth cooling flow path 310e refers to the other end on the +Y side of the fifth cooling region 312e of the fifth cooling flow path 310e.

[0060] As shown in FIGS. 2 and 3 , the fourth cooling region 312d and the fifth cooling region 312e at least partially overlap with the third battery module 100c and the fourth battery module 100d in the Z direction. The -Z side surface of the module housing 104 of the third battery module 100c and the +Z side surface of the lower plate 210 that overlaps with the third battery module 100c in the Z direction are bonded to each other via a thermally conductive material such as a thermally conductive filler. The -Z side surface of the module housing 104 of the fourth battery module 100d and the +Z side surface of the lower plate 210 that overlaps with the fourth battery module 100d in the Z direction are bonded to each other via a thermally conductive material such as a thermally conductive filler. The third battery module 100c and the fourth battery module 100d are heat-generating elements. In this embodiment, the third battery module 100c and the fourth battery module 100d can be cooled by the fourth cooling region 312d and the fifth cooling region 312e.

[0061] As shown in FIG. 3 , the fourth cooling flow path 310d at least partially extends in the Y direction, excluding the turning back of the partial convex portion of the fourth cooling region 312d of the fourth cooling flow path 310d on the -X side and the turning back of the fourth cooling flow path 310d and the fourth cooling region 312d on the -Y side. As shown in FIG. 3 , the fifth cooling flow path 310e at least partially extends in the Y direction, excluding the turning back of the fifth cooling region 312e of the fifth cooling flow path 310e on both sides of the Y direction. As described above, in each of the third battery module 100c and the fourth battery module 100d, the multiple battery cells 102 are aligned in the Y direction. Therefore, when viewed from the Z direction, the fourth cooling flow path 310d and the fifth cooling flow path 310e at least partially extend in the alignment direction of the multiple battery cells 102 of the third battery module 100c and the fourth battery module 100d. Therefore, the uniformity of cooling of the multiple battery cells 102 in each of the third battery module 100c and the fourth battery module 100d can be improved compared to when the fourth cooling flow path 310d and the fifth cooling flow path 310e extend in a direction perpendicular to the arrangement direction of the multiple battery cells 102 in the third battery module 100c and the fourth battery module 100d when viewed from the Z direction.

[0062] 2 and 3, the inlets of the fourth cooling region 312d and the fifth cooling region 312e overlap in the Z direction with the approximate center in the X direction of the -Y side portion of the third battery module 100c. The multiple battery cells 102 of each of the third battery module 100c and the fourth battery module 100d tend to generate heat more easily in the approximate center in the X direction of each battery cell 102 than at both ends in the X direction of each battery cell 102. Therefore, the uniformity of cooling of the multiple battery cells 102 of each of the third battery module 100c and the fourth battery module 100d can be improved compared to when the inlets of the fourth cooling channel 310d and the fifth cooling channel 310e are positioned offset in the X direction from the approximate center in the X direction of the third battery module 100c.

[0063] The sixth cooling channel 310f is a branch channel branched from the fifth cooling channel 310e, with one end of the sixth cooling region 312f of the sixth cooling channel 310f on the -Y side fluidly connected to the other end of the third branch introduction channel 306c opposite the inlet portion 302 via the first communicating introduction channel 306d and the second communicating introduction channel 306e, and the other end of the sixth cooling region 312f of the sixth cooling channel 310f on the +Y side fluidly connected to the -X side ends of the first upstream exhaust channel 308a1 and the second upstream exhaust channel 308b1 via the communicating exhaust channel 308d. In the example shown in FIG. 3, the fifth cooling channel 310e is alternately folded back on both sides of the fifth cooling region 312e in the X direction. The shape of the fifth cooling channel 310e is not limited to the example shown in FIG. 3.

[0064] 2 and 3, the sixth cooling region 312f and the fifth battery module 100e at least partially overlap each other in the Z direction. The fifth battery module 100e is a heat-generating element. In the embodiment, the fifth battery module 100e can be cooled by the sixth cooling region 312f.

[0065] In the embodiment, the cross-sectional area perpendicular to the channel length of the fourth cooling channel 310d and the cross-sectional area perpendicular to the channel length of the fifth cooling channel 310e are substantially equal. The flow rate of the refrigerant flowing from the third branch introduction channel 306c to the fifth cooling channel 310e is less than the flow rate of the refrigerant flowing from the second branch introduction channel 306b to the fourth cooling channel 310d because some refrigerant flows from the third branch introduction channel 306c to the sixth cooling channel 310f. Therefore, when the channel lengths of the fourth cooling channel 310d and the fifth cooling channel 310e are substantially equal, the cooling capacity of the fifth cooling region 312e may be less than the cooling capacity of the fourth cooling region 312d. However, in the embodiment, the channel length of the fourth cooling channel 310d is longer than the channel length of the fifth cooling channel 310e. Therefore, compared to when the flow path length of the fourth cooling flow path 310d and the flow path length of the fifth cooling flow path 310e are approximately equal, the cooling capacity of the fourth cooling region 312d can be made closer to the cooling capacity of the fifth cooling region 312e, and the uniformity of cooling of the third battery module 100c and the fourth battery module 100d by the fourth cooling region 312d and the fifth cooling region 312e can be improved.

[0066] The relationship between the flow rate of the refrigerant flowing from the third branch introduction channel 306c to the fifth cooling channel 310e and the flow rate of the refrigerant flowing from the third branch introduction channel 306c to the sixth cooling channel 310f can be adjusted by the cross-sectional area perpendicular to the channel length of the first communication introduction channel 306d. In the example shown in FIG. 3, the cross-sectional area perpendicular to the channel length of the first communication introduction channel 306d is less than the cross-sectional area perpendicular to the channel length of the third branch introduction channel 306c. The smaller the cross-sectional area perpendicular to the channel length of the first communication introduction channel 306d, the smaller the flow rate of the refrigerant flowing to the sixth cooling region 312f can be. The channel lengths of the fourth cooling channel 310d and the fifth cooling channel 310e can be determined, for example, depending on the cross-sectional area perpendicular to the channel length of the first communication introduction channel 306d and the channel length of the sixth cooling channel 310f. For example, the channel length of the fourth cooling channel 310d is approximately equal to the sum of the channel length of the fifth cooling channel 310e and the channel length of the sixth cooling channel 310f.

[0067] In this embodiment, the sixth cooling channel 310f for cooling the fifth battery module 100e is a branch channel branched from the fifth cooling channel 310e. However, the branch channel does not have to be a cooling channel for cooling heat-generating elements such as the fifth battery module 100e, and may simply be a channel branched from the fourth cooling channel 310d. Alternatively, the branch channel may at least partially overlap in the Z direction with a heat-generating element other than the battery module 100, such as the junction box 110.

[0068] The fourth cooling channel 310d and the fifth cooling channel 310e may have various shapes as long as the cooling uniformity of the fourth cooling region 312d and the fifth cooling region 312e can be improved. For example, even if the fourth cooling channel 310d does not have the partial bends of the embodiment and is alternately folded back on both sides in the Y direction, the channel length of the fourth cooling channel 310d can be longer than the channel length of the fifth cooling channel 310e, thereby improving the cooling uniformity of the fourth cooling region 312d and the fifth cooling region 312e.

[0069] FIG. 4 is an enlarged plan view of the periphery of the communication channel 308c of the channel 300 according to the embodiment.

[0070] The first upstream discharge flow path 308a1, the first downstream discharge flow path 308a2, the second upstream discharge flow path 308b1, and the second downstream discharge flow path 308b2 will be described with reference to FIGS.

[0071] The flow rate of the refrigerant flowing into the first upstream discharge flow path 308a1 is the sum of the flow rate of the refrigerant flowing from the fourth cooling region 312d, the flow rate of the refrigerant flowing from the fifth cooling region 312e, and the flow rate of the refrigerant flowing from the sixth cooling region 312f via the communicating discharge flow path 308d into the first upstream discharge flow path 308a1. The flow rate of the refrigerant flowing into the first downstream discharge flow path 308a2 from a region other than the first upstream discharge flow path 308a1 is the flow rate of the refrigerant flowing from the second cooling region 312b. The flow rate of the refrigerant flowing into the second upstream discharge flow path 308b1 is the flow rate of the refrigerant flowing from the sixth cooling flow path 310f via the communicating discharge flow path 308d into the second upstream discharge flow path 308b1. The sum of the flow rates of the refrigerant flowing through the fourth cooling region 312d and the fifth cooling region 312e is greater than both the flow rate of the refrigerant flowing through the second cooling region 312b and the flow rate of the refrigerant flowing through the sixth cooling flow path 310f. The flow rate of the refrigerant flowing through the second cooling region 312b is greater than the flow rate of the refrigerant flowing through the sixth cooling channel 310f. Therefore, the flow rate of the refrigerant flowing into the first downstream discharge channel 308a2 from a region other than the first upstream discharge channel 308a1 is less than the flow rate of the refrigerant flowing into the first upstream discharge channel 308a1. Furthermore, the flow rate of the refrigerant flowing into the second upstream discharge channel 308b1 is less than both the flow rate of the refrigerant flowing into the first upstream discharge channel 308a1 and the flow rate of the refrigerant flowing into the first downstream discharge channel 308a2 from a region other than the first upstream discharge channel 308a1.

[0072] In the embodiment, as described above, the flow rate of the refrigerant flowing into the first downstream discharge flow path 308a2 from a region other than the first upstream discharge flow path 308a1 is less than the flow rate of the refrigerant flowing into the first upstream discharge flow path 308a1. Therefore, resistance is generated in the flow of the refrigerant from the +X side end of the first upstream discharge flow path 308a1 toward the −X side end of the first downstream discharge flow path 308a2. In the embodiment, even if resistance is generated in the flow of the refrigerant from the +X side end of the first upstream discharge flow path 308a1 toward the −X side end of the first downstream discharge flow path 308a2, at least a portion of the refrigerant flowing through the first upstream discharge flow path 308a1 can flow into the second downstream discharge flow path 308b2 via the communication flow path 308c. By allowing the refrigerant to flow from the first upstream discharge flow path 308a1 to the second downstream discharge flow path 308b2 via the communication flow path 308c, the flow rate of the refrigerant in the second downstream discharge flow path 308b2 can be made higher than the flow rate of the refrigerant in the second upstream discharge flow path 308b1. Therefore, compared to when the refrigerant does not flow from the first upstream discharge flow path 308a1 to the second downstream discharge flow path 308b2, the flow rates of the refrigerant in the first downstream discharge flow path 308a2 and the second downstream discharge flow path 308b2 can be made equal or closer to each other, and the difference in temperature between the refrigerant in the first downstream discharge flow path 308a2 and the second downstream discharge flow path 308b2 can be eliminated or reduced. Therefore, compared to when the refrigerant does not flow from the first upstream discharge flow path 308a1 to the second downstream discharge flow path 308b2, the uniformity of cooling of the multiple battery modules 100 can be improved.

[0073] As shown in FIG. 4 , when viewed from the Z direction, the corners of the flow path 300 from the +X-side end of the first upstream discharge flow path 308a1 to the communicating flow path 308c, the corners of the flow path 300 from the −X-side end of the first downstream discharge flow path 308a2 to the communicating flow path 308c, the corners of the flow path 300 from the +X-side end of the second upstream discharge flow path 308b1 to the communicating flow path 308c, and the corners of the flow path 300 from the −X-side end of the second downstream discharge flow path 308b2 to the communicating flow path 308c are rounded. Therefore, compared to when these corners are sharp, the refrigerant can flow more smoothly from the first upstream discharge flow path 308a1 to the second downstream discharge flow path 308b2. When viewed from the Z direction, all of the above-mentioned corners do not need to be rounded. Even when at least some of the corners of the flow path 300 from the first upstream discharge flow path 308a1 to the second downstream discharge flow path 308b2 are rounded when viewed from the Z direction, the refrigerant can be smoothly flowed from the first upstream discharge flow path 308a1 to the second downstream discharge flow path 308b2.

[0074] Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various other configurations can also be adopted. [Explanation of symbols]

[0075] 10 battery pack, 100 battery module, 100a first battery module, 100b second battery module, 100c third battery module, 100d fourth battery module, 100e fifth battery module, 102 battery cell, 104 module housing, 110 junction box, 200 pack housing, 210 lower plate, 212 lower cooling plate, 214 upper cooling plate, 220 side frame, 230 upper case, 300 flow path, 302 inlet portion, 304 outlet portion, 306a first branch introduction flow path, 306b second branch introduction flow path, 306c third branch introduction flow path, 306d first communication introduction flow path, 306e second communication introduction flow path, 308a1 first upstream discharge flow path, 308a2 first downstream discharge flow path, 308b1 second upstream discharge flow path, 308b2 second downstream discharge flow path, 308c Communication flow path, 308d communication exhaust flow path, 310 cooling flow path, 310a first cooling flow path, 310b second cooling flow path, 310c third cooling flow path, 310d fourth cooling flow path, 310e fifth cooling flow path, 310f sixth cooling flow path, 312 cooling region, 312a first cooling region, 312b second cooling region, 312c third cooling region, 312d fourth cooling region, 312e fifth cooling region, 312f sixth cooling region

Claims

1. A battery module; a flow path for flowing a refrigerant for cooling the battery module; Equipped with the flow path includes a plurality of cooling flow paths at least partially overlapping with the battery module, and a branch flow path branching from at least one of the cooling flow paths; A battery pack, wherein the flow path length of at least one other of the cooling flow paths is longer than the flow path length of the at least one other of the cooling flow paths.

2. the battery module has a plurality of battery cells arranged in a predetermined direction, The battery pack according to claim 1 , wherein the plurality of cooling channels extend at least partially in the predetermined direction.

3. 3. The battery pack according to claim 2, wherein the plurality of cooling channels are configured to allow the refrigerant to flow from portions of the plurality of cooling channels that overlap with approximate centers of the battery modules in a direction perpendicular to the predetermined direction.

4. The battery pack according to claim 2 , wherein a plurality of the battery modules are arranged in the predetermined direction.

5. 5. The battery pack according to claim 1, wherein the branch flow path at least partially overlaps a heat generating element different from the battery module.

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