Battery pack and method for manufacturing battery pack

Abstract

To reduce the number of parts, to facilitate assembly and to reduce an assembly cost.SOLUTION: The battery pack 1 includes the plurality of battery cells 2, the case 3 that houses the plurality of battery cells 2, and the cooler 4 that is provided inside the case 3 and cools the battery cells 2 with the coolant, the cooler 4 includes the plurality of coolers 10, each of the coolers 10 includes the flow path 13 through which the coolant flows and the cooling-surface 10a that is in contact with the battery cell 2, and the plurality of coolers 10 and the plurality of battery cells 2 are alternately stacked in the X direction inside the case 3. The cooler 4 is an integral structure in which a plurality of coolers 10 are joined, and the coolers 10 are deformable so as to displace the cooled surface 10a in the X direction according to the pressure inside the coolers 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a battery pack in which a cooling device for cooling battery cells is provided inside a case that houses the battery cells. In the configuration described in Patent Document 1, the cooling device has multiple coolers, and the multiple coolers and multiple battery cells are stacked alternately. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2024-509489 Summary of the Invention [Problem to be solved by the invention]

[0004] The configuration described in Patent Document 1 requires a separate pipe member to connect adjacent coolers, which increases the number of parts and complicates assembly, resulting in increased assembly costs.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a battery pack and a method for manufacturing the battery pack that can reduce the number of parts, facilitate assembly, and reduce assembly costs. [Means for solving the problem]

[0006] The present invention provides a battery pack comprising a plurality of battery cells, a case that houses the plurality of battery cells, and a cooling device that is provided inside the case and cools the battery cells with a coolant, wherein the cooling device has a plurality of coolers, each of which has a flow path through which the coolant flows and a cooling surface that contacts the battery cells, and inside the case, the plurality of coolers and the plurality of battery cells are stacked alternately in a first direction, and the cooling device is an integrated structure to which the plurality of coolers are joined, and the coolers are deformable to displace the cooling surface in the first direction in accordance with the pressure inside the coolers.

[0007] According to this configuration, the cooler having an integral structure can be installed in the case, which makes assembly easier and reduces assembly costs.

[0008] Furthermore, when the cooler is placed inside the case and the pressure inside the cooler becomes negative pressure which is lower than the pressure outside the cooler, the cooler may be deformed so as to displace the cooling surface to a position where it does not come into contact with the battery cells.

[0009] This configuration makes it easy to insert the battery cells between the coolers.

[0010] The cooler may also have a diaphragm portion including the cooling surface, a flat plate portion formed on the periphery of the diaphragm portion and extending in a second direction perpendicular to the first direction, and a pipe portion extending from the flat plate portion in the first direction.

[0011] With this configuration, when inserting a battery cell between the coolers, the diaphragm portion can deform the cooling surface to create a recess, making it easier to insert the battery cell.

[0012] Furthermore, between adjacent coolers, the pipe portion of one cooler may be joined to the pipe portion of the other cooler.

[0013] According to this configuration, the coolers are joined together, so the number of parts can be reduced.

[0014] Furthermore, when the cooler is placed inside the case and the pressure inside the cooler is greater than the pressure outside the cooler, the cooler may deform so as to displace the cooling surface to a position where it comes into contact with the battery cell.

[0015] With this configuration, by increasing the pressure inside the cooler, the cooler expands and deforms, allowing the cooling surface to come into close contact with the battery cells.

[0016] The present invention is a method for manufacturing a battery pack, comprising: a joining step of forming an integrated cooling device consisting of a plurality of coolers and joining the plurality of coolers so that the cooling surfaces of the coolers face each other; an installation step of installing the integrated cooling device inside a case for accommodating a plurality of battery cells; a deformation step of deforming the coolers after the integrated cooling device has been installed inside the case, by creating a negative pressure state in which the pressure inside the coolers is lower than the pressure outside the coolers, and displacing the cooling surfaces to a position where they do not contact the battery cells; an insertion step of inserting the battery cells between adjacent coolers with the cooling surfaces displaced due to the negative pressure state; and a contact step of releasing the negative pressure state and bringing the cooling surfaces into contact with the battery cells after the battery cells have been inserted between the coolers.

[0017] With this configuration, the inside of the cooler is put into a negative pressure state when the battery cells are placed between the coolers, making it easier to insert the battery cells. Also, because the cooling device is an integrated structure, assembly is easier and assembly costs can be reduced.

[0018] The cooling device having an integral structure may have a structure in which the coolers are joined together, and the joining step may include a step of joining the coolers together by brazing.

[0019] According to this configuration, an integral structure can be formed by brazing, making assembly easy.

[0020] The inserting step may include a step of placing the battery cell inside the case in a position where the battery cell and the cooling surface do not come into contact with each other when the cooler is in a deformed state, and the contacting step may include a step of abutting the cooling surface against the battery cell to form a stack in which the cooler and the battery cell are stacked, and compressing the battery cell in the stacking direction of the stack with the cooler.

[0021] This configuration makes it easy to insert the battery cells and simplifies assembly.

[0022] The present invention is a method for manufacturing a battery pack, comprising the steps of: forming an integrated cooling device consisting of a plurality of coolers, and joining the plurality of coolers so that the cooling surfaces of the coolers face each other; installing the integrated cooling device inside a case for accommodating a plurality of battery cells; inserting the battery cells between adjacent coolers after the integrated cooling device has been installed inside the case; and deforming the coolers after the battery cells have been inserted between the coolers, making the pressure inside the coolers greater than the pressure outside the coolers, and displacing the cooling surfaces into a position where they come into contact with the battery cells.

[0023] This configuration makes it easy to insert the battery cells when arranging them between the coolers. Also, because the cooling device is an integrated structure, assembly is easy and assembly costs can be reduced.

[0024] The cooling device of the integral structure may have a structure in which the cooler is joined to a pipe, and the joining step may include a step of joining the cooler and the pipe by brazing.

[0025] According to this configuration, the cooler and the pipe can be brazed to form an integrated structure, which makes assembly easier.

[0026] The inserting step may include a step of positioning the battery cells inside the case in a position where the battery cells do not come into contact with the cooling surface when the cooler is not deformed, and the deforming step may include a step of abutting the cooling surface against the battery cells to form a stack in which the cooler and the battery cells are stacked, and compressing the battery cells in the stacking direction of the stack with the cooler.

[0027] With this configuration, there is no need to deform the cooler when inserting the battery cells, making it easier to insert the battery cells. [Effects of the Invention]

[0028] In the present invention, the number of parts can be reduced, assembly is facilitated, and assembly costs can be reduced. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a diagram schematically illustrating a battery pack according to an embodiment. [Figure 2] FIG. 2 is a diagram showing a cooling device for a monolithic structure. [Figure 3] FIG. 3 is a diagram showing a cooler. [Figure 4] FIG. 4 is a diagram for explaining the structure of the cooler. [Figure 5] FIG. 5 is a diagram for explaining a state in which the coolant flows through the cooler. [Figure 6] FIG. 6 is a flowchart showing a method for manufacturing a battery pack. [Figure 7] FIG. 7 is a diagram showing the cooling device installed inside the case. [Figure 8] FIG. 8 is a diagram showing a state in which the inside of the cooler is put into a negative pressure state and the cooler is deformed. [Figure 9]FIG. 9 is a diagram for explaining the state before the cooler is deformed. [Figure 10] FIG. 10 is a diagram for explaining a state in which the cooler is deformed. [Figure 11] FIG. 11 is a diagram illustrating the state in which a battery cell is inserted between coolers in a deformed state. [Figure 12] FIG. 12 is a diagram showing a structure in which a plurality of battery cells are arranged in the Y direction. [Figure 13] FIG. 13 is a diagram schematically showing a battery pack according to a modified example. [Figure 14] FIG. 14 is a diagram showing a cooling device for an integral structure according to a modified example. [Figure 15] FIG. 15 is a diagram for explaining the cooling device. [Figure 16] FIG. 16 is a diagram for explaining the state of the cooler after it has been deformed. [Figure 17] FIG. 17 is a diagram for explaining the state before the cooler is deformed. [Figure 18] FIG. 18 is a flowchart showing a manufacturing method of a battery pack according to a modified example. [Figure 19] FIG. 19 is a diagram for explaining an installation process for arranging the cooling device inside the case. [Figure 20] FIG. 20 is a diagram illustrating the insertion step of inserting a battery cell. [Figure 21] FIG. 21 is a diagram for explaining the deformation step of deforming the cooler. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, a battery pack and a method for manufacturing the battery pack according to an embodiment of the present invention will be specifically described, but the present invention is not limited to the embodiment described below.

[0031] Figure 1 is a diagram schematically illustrating a battery pack according to an embodiment. The battery pack 1 includes a plurality of battery cells 2, a case 3 for accommodating the plurality of battery cells 2, and a cooling device 4 for cooling the battery cells 2. For example, the battery pack 1 is mounted on an electric vehicle. In the electric vehicle equipped with the battery pack 1, the electric power stored in the battery pack 1 is supplied to a driving motor.

[0032] The battery cell 2 is a battery formed in a rectangular parallelepiped shape. The battery cell 2 includes a flat surface 2a that has the largest area among the surfaces of the battery cell 2. The battery cell 2 is placed inside the case 3 with the flat surface 2a facing in the X direction. The X direction is a first direction. Inside the case 3, multiple battery cells 2 are stacked in the X direction.

[0033] The case 3 is a case for accommodating a plurality of battery cells 2. The case 3 accommodates a cooling device 4 together with the plurality of battery cells 2. For example, the case 3 has an upper case and a lower case. Inside the case 3, the plurality of battery cells 2 can configure a battery module. Therefore, the case 3 can accommodate a plurality of battery modules each consisting of a plurality of battery cells 2.

[0034] The cooling device 4 is provided inside the case 3 and cools the battery cells 2 with a coolant. The cooling device 4 includes multiple coolers 10. The coolers 10 have cooling surfaces 10a that come into contact with the battery cells 2. The coolers 10 are made of metal members. As shown in FIG. 2, the cooling device 4 is an integrated structure in which multiple coolers 10 are joined together, with the cooling surfaces 10a of the coolers 10 facing each other. In the cooling device 4, the coolers 10 are brazed to each other.

[0035] When the battery pack 1 is completed, a stack is formed inside the case 3, with multiple coolers 10 and multiple battery cells 2 alternately stacked in the X direction, and the coolers 10 are located on both ends of the stack in the stacking direction. The stacking direction is the same as the X direction. Because the battery cells 2 are rectangular and the coolers 10 are flat, one battery cell 2 is sandwiched between two coolers 10. The battery cells 2 and the coolers 10 are stacked so that the surfaces with the largest areas among their multiple surfaces are in contact. The cooling surface 10a is in contact with the flat surface 2a of the battery cell 2.

[0036] As shown in FIG. 3, the cooler 10 has a cooling section 11 and a pipe section 12.

[0037] The cooling section 11 is formed in the shape of a hollow plate. A flow path 13 through which a coolant flows is provided inside the cooling section 11. The internal space of the cooling section 11 is the flow path 13 for the coolant. As shown in FIG. 1, when the cooling device 4 is housed in the case 3, the cooling section 11 extends in the Y direction, which is perpendicular to the X direction. The Y direction is the second direction. The cooling section 11 is disposed between the battery cells 2, and forms a stack together with the battery cells 2. The cooling section 11 includes a cooling surface 10a. As shown in FIG. 4, when the cooler 10 is viewed from the X direction, the cooling section 11 is formed in a rectangular shape. The cooling section 11 has a diaphragm portion 14 and a flat plate portion 15.

[0038] The diaphragm portion 14 is a portion that includes the cooling surface 10a and is deformable to displace the cooling surface 10a in the X direction in response to the pressure inside the cooler 10. The cooling portion 11 has diaphragm portions 14 on both sides in the X direction. The cooler 10 is deformable so that the thickness of the cooling portion 11 changes as the diaphragm portions 14 deform. The diaphragm portion 14 has a groove portion 14a formed in a frame shape to surround the cooling surface 10a. The diaphragm portion 14 can elastically deform to displace the cooling surface 10a surrounded by the groove portion 14a in the X direction. The diaphragm portion 14 can return to its original shape after being deformed to recess the cooling surface 10a.

[0039] As shown in Fig. 4, the diaphragm portion 14 is formed in a rectangular shape with the Y direction as the longitudinal direction and the Z direction as the lateral direction. The Z direction is perpendicular to the Y direction and perpendicular to the X direction. The groove portion 14a is formed in a quadrangular frame shape with the Y direction as the longitudinal direction and the Z direction as the lateral direction. The cooling surface 10a is formed in a rectangular shape with the Y direction as the longitudinal direction and the Z direction as the lateral direction.

[0040] The flat plate portion 15 is formed on the periphery of the diaphragm portion 14 and extends in the Y direction. The flat plate portion 15 includes a flat surface facing the X direction. The flat plate portion 15 supports the diaphragm portion 14 and does not deform even when the diaphragm portion 14 deforms. The rigidity of the flat plate portion 15 is higher than the rigidity of the groove portion 14a. The tube portion 12 is provided on the part of the flat plate portion 15 that is outside the diaphragm portion 14 in the Y direction.

[0041] The pipe portion 12 is a linear pipe portion extending in the X direction from the flat plate portion 15. The pipe portion 12 is in communication with the flow path 13.

[0042] The pipe section 12 includes a first pipe section 16 that supplies the coolant to the flow path 13 and a second pipe section 17 through which the coolant that has circulated through the flow path 13 flows. The first pipe section 16 is a supply pipe section provided upstream of the flow path 13. The second pipe section 17 is a discharge pipe section provided downstream of the flow path 13. As shown in FIG. 5 , the coolant supplied to the cooler 10 flows from the first pipe section 16 into the flow path 13 in the cooling section 11. Inside the cooling section 11, the coolant circulates in the Y direction within the flow path 13 from the inlet on the first pipe section 16 side to the outlet on the second pipe section 17 side. The coolant that has circulated within the cooling section 11 flows out from the flow path 13 to the second pipe section 17.

[0043] The pipe section 12 also includes a third pipe section 18 and a fourth pipe section 19. The third pipe section 18 is a connecting pipe section that is connected to an adjacent cooler 10, and allows the coolant to circulate before exchanging heat with the battery cells 2. In a cooler 10 that includes the third pipe section 18, the third pipe section 18 is provided downstream of the first pipe section 16, and the downstream side of the first pipe section 16 branches into the flow path 13 and the third pipe section 18. The third pipe section 18 supplies the coolant that has flowed from the first pipe section 16 into the inside of the flat plate section 15 to the adjacent cooler 10. Between adjacent coolers 10, the third pipe section 18 of one cooler 10 is connected to the first pipe section 16 of the other cooler 10.

[0044] The fourth pipe section 19 is a connecting pipe section that is connected to an adjacent cooler 10, and circulates the coolant after heat exchange with the battery cells 2. The fourth pipe section 19 is connected to the second pipe section 17 of the adjacent cooler 10. Between adjacent coolers 10, the fourth pipe section 19 of one cooler 10 is connected to the second pipe section 17 of the other cooler 10. The fourth pipe section 19 supplies the coolant that flows in from the adjacent cooler 10 to the second pipe section 17 of its own cooler 10. In a cooler 10 that includes the fourth pipe section 19, the fourth pipe section 19 is provided upstream of the second pipe section 17, and the flow path 13 and the fourth pipe section 19 merge upstream of the second pipe section 17.

[0045] Between adjacent coolers 10, the pipe portion 12 of one cooler 10 is joined to the pipe portion 12 of the other cooler 10. As shown in FIG. 2 , between adjacent coolers 10, the third pipe portion 18 of one cooler 10 is fitted to the first pipe portion 16 of the other cooler 10. The third pipe portion 18 and the first pipe portion 16, which are fitted together, are joined by brazing. Similarly, between adjacent coolers 10, the fourth pipe portion 19 of one cooler 10 is fitted to the second pipe portion 17 of the other cooler 10. The fourth pipe portion 19 and the second pipe portion 17, which are fitted together, are joined by brazing.

[0046] 5, in the cooling device 4, the flow paths 13 in the coolers 10 are connected in parallel, and the coolant flows through each of the flow paths 13. The multiple coolers 10 are connected by pipe sections 12. In the cooler 10 arranged at one end in the X direction, the first pipe section 16 serves as the inlet of the cooling device 4, and the second pipe section 17 serves as the outlet of the cooling device 4. The cooler 10 arranged at the other end in the X direction does not have the third pipe section 18 or the fourth pipe section 19.

[0047] 6 is a flowchart showing a method for manufacturing the battery pack 1. The method for manufacturing the battery pack 1 includes a joining step (step S1), an installation step (step S2), a deformation step (step S3), an insertion step (step S4), and a contact step (step S5).

[0048] First, in a joining process, a plurality of coolers 10 are joined (step S1). In the joining process, the plurality of coolers 10 are joined by brazing so that the coolers 10 form an integrated structure with their cooling surfaces 10a facing each other. At this time, the coolers 10 are brazed to each other. In the joining process, all of the coolers 10 are joined, and all of the components constituting the cooling device 4 are joined by brazing. For example, in the joining process, a paste containing a brazing material is applied to the parts to be joined, and then the parts are placed in a furnace to be brazed. The parts to be joined include the part where the first pipe portion 16 is fitted into the third pipe portion 18 and the part where the second pipe portion 17 is fitted into the fourth pipe portion 19.

[0049] Next, in the installation step, the integrally structured cooling device 4 is installed inside the case 3 (step S2). In the installation step, as shown in Fig. 7, the integrally structured cooling device 4 is installed inside the case 3 in a state where the battery cells 2 are not installed.

[0050] Next, in the deformation process, the inside of the cooler 10 is placed in a negative pressure state, thereby denting the diaphragm portion 14 (step S3). In the deformation process, after the cooling device 4 is placed inside the case 3, as shown in FIG. 8 , the most downstream second pipe portion 17 is closed by a valve or the like, and the fluid inside the cooler 10 is sucked from the most upstream first pipe portion 16, thereby placing the inside of the cooler 10 in a negative pressure state. The negative pressure state of the cooler 10 is a state in which the pressure inside the cooler 10 is lower than the pressure outside the cooler 10. In this case, the fluid sucked from the inside of the cooler 10 may be either gas or liquid. By placing the inside of the cooler 10 in a negative pressure state, the diaphragm portion 14 deforms, and the cooler 10 can be deformed so that the flow path 13 inside the cooler 10 narrows in the X direction. The diaphragm portion 14 can be deformed to reduce the thickness of the cooling portion 11 by placing the inside of the cooler 10 in a negative pressure state.

[0051] As shown in FIG. 9, before the inside of the cooler 10 is placed in a negative pressure state and the diaphragm portion 14 is not deformed, the X-direction thickness of the cooling portion 11 of the cooler 10 is thickness D1. As shown in FIG. 10, before the inside of the cooler 10 is placed in a negative pressure state and the diaphragm portion 14 is deformed, the X-direction thickness of the cooling portion 11 of the cooler 10 is thickness D2. The thickness D2 after deformation is thinner than the thickness D1 before deformation. In the deformation process, when the diaphragm portion 14 is deformed so that the thickness of the cooling portion 11 becomes thinner like thickness D2, the cooler 10 is deformed so that the cooling surface 10a is displaced to a position where it does not contact the battery cell 2. In the deformation process, before the battery cell 2 is placed inside the case 3, the inside of the cooler 10 is placed in a negative pressure state and the diaphragm portion 14 is deformed so that the cooling surface 10a is displaced to a position where it does not contact the flat surface 2a.

[0052] Next, in the insertion process, the battery cells 2 are inserted between the coolers 10 (step S4). In the insertion process, the inside of the coolers 10 is in a negative pressure state, causing the diaphragm portion 14 to deform so as to displace the cooling surfaces 10a, and the battery cells 2 are inserted into the space between adjacent coolers 10 where the cooling surfaces 10a face each other. When the inside of the coolers 10 is in a negative pressure state and the diaphragm portion 14 deforms, the cooling surfaces 10a are displaced in the X direction to a position where they do not come into contact with the flat surfaces 2a of the battery cells 2. This displacement ensures a gap between the battery cells 2 and the cooling surfaces 10a in the X direction. In the insertion process, with the coolers 10 in a deformed state, the battery cells 2 are placed in a position in the space where the cooling surfaces 10a face each other, so that the battery cells 2 do not come into contact with the cooling surfaces 10a.

[0053] Then, in the contact step, the negative pressure state of the cooler 10 is released and the cooling surface 10a is brought into contact with the battery cell 2 (step S5). In the contact step, after the battery cell 2 is inserted into the space between the opposing cooling surfaces 10a, the suction of fluid from the first pipe portion 16 is stopped, the negative pressure state of the cooler 10 is released, and the deformation of the diaphragm portion 14 is released. When the deformation of the diaphragm portion 14 is released, the X-direction thickness of the cooling portion 11 attempts to return to thickness D1 from thickness D2, so that the cooling surface 10a can be brought into contact with the flat surface 2a of the battery cell 2. In the contact step, the cooling surface 10a is brought into contact with the battery cell 2 to form a stack in which the cooler 10 and battery cell 2 are stacked, and the cooler 10 compresses the battery cell 2 in the stacking direction of the stack.

[0054] As described above, according to the embodiment, pipe members for connecting adjacent coolers 10 are not required, and the number of parts can be reduced. In the cooling device 4, all of the coolers 10 are joined by brazing, which makes assembly easier and reduces assembly costs.

[0055] The number of battery cells 2 is not particularly limited. The number of battery cells 2 stacked in the X direction (number of layers) is not limited. Alternatively, a structure in which multiple battery cells 2 are arranged side by side in the Y direction may be used. As shown in FIG. 12, the battery pack 1 has a structure in which four battery cells 2 are arranged side by side in the Y direction and seven battery cells 2 are arranged stacked in the X direction. In this case, one cooling surface 10a comes into contact with four battery cells 2.

[0056] Furthermore, the cooling device 4 may be an integral structure in which the components constituting the cooling device 4 are joined together, and is not limited to a structure in which the coolers 10 are joined together. Furthermore, the cooling device 4 may be configured so that the cooling surface 10a is displaced in the X direction in response to the pressure inside the cooler 10, and is not limited to a structure in which the diaphragm portion 14 is deformed by creating a negative pressure inside the cooler 10. Therefore, examples of modified examples of the battery pack 1 are shown in Figs. 13 to 17.

[0057] As shown in Fig. 13, the battery pack 1 of the modified example includes a cooling device 4 including coolers 20 and pipes 30. The cooling device 4 includes a plurality of coolers 20 and a pair of pipes 30. The coolers 20 are configured to be deformable so that their thickness in the X direction increases. Fig. 13 shows the cooler 20 after deformation, in which the thickness in the X direction has increased.

[0058] As shown in FIG. 14, the cooling device 4 is an integrated structure in which multiple coolers 20 are joined to a pair of pipes 30. The coolers 20 have a cooling section 21 and a connecting section 22. The cooling section 21 is a section that includes a cooling surface 20a. The cooling section 21 is a hollow plate member and has a flow path 23 formed therein. A coolant flows through the flow path 23. The cooling section 21 is disposed between the battery cells 2 and forms a stack together with the battery cells 2. The connecting sections 22 are formed on both ends of the cooling section 21 and are connected to the pipes 30. In the cooling device 4, the coolers 20 are disposed so that their cooling surfaces 20a face each other, and the connecting sections 22 of the coolers 20 are brazed to the pipes 30. Both the coolers 20 and the pipes 30 are made of metal. FIG. 14 shows the cooler 20 before deformation, in which its thickness in the X direction remains thin.

[0059] As shown in FIG. 15, the pipe 30 is a square pipe extending in the X direction. The pipe 30 has a plurality of connection ports 31. The connection ports 31 are openings that open in the Y direction. For example, the pipe 30 is formed by extrusion molding, and the connection ports 31 are formed by machining. The connection portion 22 of the cooler 20 is connected to the connection port 31. The connection portion 22 of the cooler 20 fits into the connection port 31 of the pipe 30. The fitted connection portion 22 and connection port 31 are joined by brazing. A plurality of coolers 20 are connected to the pipe 30. FIG. 15 shows the cooler 20 after deformation, with its thickness increased in the X direction.

[0060] A first end cap 32 and a second end cap 33 are brazed to the pipe 30. The first end cap 32 is joined to the pipe 30 so as to cover one open end of the pipe 30 in the X direction. The second end cap 33 is joined to the pipe 30 so as to cover the other open end of the pipe 30 in the X direction. The first end cap 32 and the second end cap 33 are formed by machining. As shown in FIG. 14 , in a pair of pipes 30, a first pipe section 34 is joined to the first end cap 32 of one pipe 30, and a second pipe section 35 is joined to the first end cap 32 of the other pipe 30. The first pipe section 34 is the pipe section on the inlet side. The coolant supplied to the cooling device 4 flows into the cooling device 4 from the first pipe section 34. The second pipe section 35 is the pipe section on the outlet side. The coolant discharged from the cooling device 4 flows out of the cooling device 4 from the second pipe section 35. The first pipe portion 34 and the second pipe portion 35 are formed by extrusion molding.

[0061] As shown in Fig. 15, the cooling section 21 is composed of a multi-hole pipe extending in the Y direction. The cooling section 21 has a plurality of flow paths 23 partitioned in the Z direction. The connection section 22 has one flow path that is not partitioned in the Z direction. The flow path of the cooler 20 is formed so that it branches from the flow path of the connection section 22 on the upstream side into the plurality of flow paths 23 of the cooling section 21 and merges at the flow path of the connection section 22 on the downstream side from the cooling section 21.

[0062] The cooling section 21 has a deforming section 21a. The deforming section 21a is a portion that deforms so that the thickness of the cooling section 21 in the X direction increases. As shown in FIGS. 16 and 17, the deforming section 21a is formed in a shape that is inclined with respect to the X direction and with respect to the Z direction. The deforming section 21a includes a deforming section 21a that is formed in an inverted V shape toward one side in the Z direction, and a deforming section 21a that is formed in a V shape toward the other side in the Z direction. FIG. 16 shows the shape of the deforming section 21a after deformation, and FIG. 17 shows the shape of the deforming section 21a before deformation.

[0063] 14 and 17, before deformation portion 21a is deformed, cooling portion 21 has a thin thickness in the X direction. As shown in FIGS. 13, 15, and 16, after deformation portion 21a is deformed, cooling portion 21 has a thick thickness in the X direction.

[0064] 18 is a flowchart showing a manufacturing method of a battery pack according to a modified example. The manufacturing method of this battery pack 1 includes a joining step (step S11), an installation step (step S12), an insertion step (step S13), and a deformation step (step S14).

[0065] First, in the joining process, a plurality of coolers 20 and a pair of pipes 30 are joined together (step S11). In the joining process, an integrally structured cooling device 4 is formed, and the components of the cooling device 4 are joined so that the cooling surfaces 20a of the coolers 20 face each other. In the joining process, all components can be brazed together by applying a paste containing brazing material to the areas to be joined and then placing the components in a furnace.

[0066] The components of the cooling device 4 include a cooler 20, a pipe 30, a first end cap 32, a second end cap 33, a first pipe section 34, and a second pipe section 35. The first pipe section 34 is brazed to one of the first end caps 32. The second pipe section 35 is brazed to the other first end cap 32. The first end cap 32 is brazed to the pipe 30 so as to cover one open end of the pipe 30. The second end cap 33 is brazed to the pipe 30 so as to cover the other open end of the pipe 30. The connecting section 22 of the cooler 20 is brazed to the pair of pipes 30.

[0067] Next, in the installation step, the integrally structured cooling device 4 is installed inside the case 3 (step S12). In the installation step, as shown in Fig. 19, the integrally structured cooling device 4 is installed inside the case 3 in a state where the battery cells 2 are not installed.

[0068] Next, in the insertion step, the battery cells 2 are inserted between the coolers 20 (step S13). In the insertion step, as shown in Fig. 20, the battery cells 2 are inserted into the space between adjacent coolers 20 where the cooling surfaces 20a face each other. In the insertion step, when the coolers 20 are not deformed, the battery cells 2 are placed in a position in the space where the cooling surfaces 20a face each other so that the flat surfaces 2a and the cooling surfaces 20a do not come into contact with each other.

[0069] Then, in the deformation process, the pressure inside the cooler 20 is increased to expand the cooling section 21, which is made of a multi-hole tube (step S14). In the deformation process, after the cooling device 4 is placed inside the case 3, as shown in FIG. 21 , the second pipe section 35 is closed using a valve 60 or the like, and the coolant inside the cooler 20 is supplied from the first pipe section 34 using a pump 50 or the like to apply pressure to the inside of the cooler 20. At this time, the pressure inside the cooler 20 is made greater than the pressure outside the cooler 20. For example, the cooling section 21 is expanded at a pressure greater than atmospheric pressure but less than 2 MPa. By increasing the pressure inside the cooler 20, the deformation section 21a can be deformed so that the flow path 23 inside the cooler 20 becomes wider in the X direction. In the deformation process, the cooling section 21 is deformed to increase its thickness in the X direction, thereby bringing the cooling surface 20a into close contact with the battery cell 2. In other words, the deformation process includes a contact process. In the deformation process, the cooler 20 is deformed to bring the cooling surfaces 20a into contact with the flat surfaces 2a of the battery cells 2. After the battery cells 2 are inserted into the space between the opposing cooling surfaces 20a, the pump 50 supplies coolant to the first pipe section 34, increasing the pressure inside the cooler 20. When the pressure inside the cooler 20 increases and the cooling section 21 deforms to increase its thickness in the X direction, the cooling surfaces 20a can be brought into tight contact with the flat surfaces 2a. In the deformation process, the cooling surfaces 20a are brought into contact with the battery cells 2 to form a stack in which the cooler 20 and the battery cells 2 are stacked, and the cooler 20 compresses the battery cells 2 in the stacking direction of the stack.

[0070] In this way, even in the battery pack 1 of the modified example, all of the components of the cooling device 4 are joined by brazing, which makes assembly easy and reduces assembly costs. In addition, since it is not necessary to provide a part for connecting adjacent coolers 20 at each opposing location, an increase in the number of parts can be suppressed. [Explanation of symbols]

[0071] 1 battery pack 2 battery cells 2a flat surface 3 Cases 4 Cooling device 10 Cooler 10a cooling surface 11 Cooling section 12 Pipe section 13 Flow path 14 Diaphragm part 14a Groove 15 Flat plate part 16 First Pipe Section 17 Second Pipe Section 18 Third Pipe Section 19 Fourth Pipe Section 20 Cooler 20a cooling surface 21 Cooling section 22 Connection 23 Flow path 30 Pipe 31 Connection port 32 First end cap 33 Second end cap 34 First Pipe Section 35 Second Pipe Section

Claims

1. A plurality of battery cells; a case that houses the plurality of battery cells; a cooling device provided inside the case that cools the battery cells with a coolant; Equipped with the cooling device includes a plurality of coolers; the cooler has a flow path through which the coolant flows and a cooling surface that contacts the battery cell; a battery pack in which a plurality of the coolers and a plurality of the battery cells are alternately stacked in a first direction inside the case, the cooling device is an integral structure in which the plurality of coolers are joined together, The cooler is deformable to displace the cooling surface in the first direction in response to pressure inside the cooler. A battery pack characterized by:

2. When the cooler is placed inside the case and the pressure inside the cooler is in a negative pressure state that is lower than the pressure outside the cooler, the cooler deforms so as to displace the cooling surface to a position that does not contact the battery cells.

2. The battery pack according to claim 1, wherein the battery pack is a battery pack having a plurality of electrodes.

3. The cooler is a diaphragm portion including the cooling surface; a flat plate portion formed on a periphery of the diaphragm portion and extending in a second direction perpendicular to the first direction; a tubular portion extending from the flat plate portion in the first direction; 3. The battery pack according to claim 2.

4. Between adjacent coolers, the pipe portion of one cooler is joined to the pipe portion of the other cooler.

4. The battery pack according to claim 3.

5. When the cooler is disposed inside the case and the pressure inside the cooler is greater than the pressure outside the cooler, the cooler deforms to displace the cooling surface to a position where it comes into contact with the battery cell.

2. The battery pack according to claim 1, wherein the battery pack is a battery pack having a plurality of electrodes.

6. A method for manufacturing a battery pack, comprising: a joining step of forming a cooling device having an integral structure including a plurality of coolers and joining the plurality of coolers so that cooling surfaces of the coolers face each other; an installation step of installing the integrated cooling device inside a case for accommodating a plurality of battery cells; a deformation step in which, after the integrated cooling device is installed inside the case, the pressure inside the cooler is made to be a negative pressure that is lower than the pressure outside the cooler, and the cooler is deformed so that the cooling surface is displaced to a position where it does not contact the battery cells; an insertion step of inserting the battery cells between adjacent coolers in a state in which the cooling surfaces are displaced due to the negative pressure state; a contact step of releasing the negative pressure state after the battery cell is inserted between the coolers and bringing the cooling surface into contact with the battery cell; A method for manufacturing a battery pack, comprising:

7. The cooling device of the integral structure has a structure in which the coolers are joined to each other, The joining step includes a step of joining the coolers to each other by brazing. The method for manufacturing a battery pack according to claim 6 .

8. the inserting step includes a step of arranging the battery cell inside the case at a position where the battery cell does not contact the cooling surface when the cooler is in a deformed state; The contact step includes a step of abutting the cooling surface against the battery cells to form a stack in which the cooler and the battery cells are stacked, and compressing the battery cells with the cooler in the stacking direction of the stack. The method for manufacturing a battery pack according to claim 7 .

9. A method for manufacturing a battery pack, comprising: a joining step of forming a cooling device having an integral structure including a plurality of coolers and joining the plurality of coolers so that cooling surfaces of the coolers face each other; an installation step of installing the integrated cooling device inside a case for accommodating a plurality of battery cells; an inserting step of inserting the battery cells between adjacent coolers after the integral cooling device is installed inside the case; a deformation step of deforming the cooler after the battery cells are inserted between the coolers, by making the pressure inside the cooler greater than the pressure outside the cooler, and displacing the cooling surface to a position where it contacts the battery cells; A method for manufacturing a battery pack, comprising:

10. The cooling device of the integral structure has a structure in which the cooler is joined to a pipe, The joining step includes a step of joining the cooler and the pipe by brazing. The method for manufacturing a battery pack according to claim 9 .

11. the inserting step includes a step of arranging the battery cell inside the case at a position where the battery cell does not contact the cooling surface when the cooler is not deformed, The deformation step includes a step of abutting the cooling surface against the battery cells to form a stack in which the cooler and the battery cells are stacked, and compressing the battery cells in the stack direction of the stack with the cooler. The method for manufacturing a battery pack according to claim 10 .

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