Method for manufacturing a cooler and battery pack

Abstract

To prevent the cooling fluid passages from being blocked by batteries that swell during use, thereby ensuring cooling performance. [Solution] A cooler that is stacked alternately with batteries to cool the batteries, having a cooling section positioned between adjacent batteries in the stacking direction, the cooling section having a flow path through which a cooling liquid flows, a first cooling surface which is a cooling surface that contacts one of the batteries, a second cooling surface which is a cooling surface that contacts the other of the batteries, a first projection that protrudes from the back surface of the first cooling surface toward the back surface of the second cooling surface in the stacking direction, and a second projection that protrudes from the back surface of the second cooling surface toward the back surface of the first cooling surface in the stacking direction, the flow path is formed by an internal space where the back surfaces of the cooling surfaces face each other, and when the first cooling surface and the second cooling surface are in surface contact with the batteries, the first projection and the second projection face each other in the stacking direction inside the cooling section.

Description

Technical Field

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

Background Art

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

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a structure in which battery cells and coolers are alternately stacked as in the configuration described in Patent Document 1, during use, when the battery cells expand, the coolers are deformed so as to be compressed. In this case, when the coolers are greatly compressed, the flow path of the coolant provided inside the coolers becomes narrow, and the cooling performance deteriorates.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a cooler and a method for manufacturing a battery pack that can prevent the flow path of the coolant from being blocked by the expanded battery during use and ensure the cooling performance.

Means for Solving the Problems

[0006] The cooler according to the present invention is a cooler that is stacked alternately with batteries and cools the batteries, and has a cooling section disposed between adjacent batteries in the stacking direction, the cooling section having a flow path through which a cooling liquid flows, a first cooling surface which is a cooling surface that contacts one of the batteries, a second cooling surface which is a cooling surface that contacts the other of the batteries, a first projection that protrudes from the back surface of the first cooling surface toward the back surface of the second cooling surface in the stacking direction, and a second projection that protrudes from the back surface of the second cooling surface toward the back surface of the first cooling surface in the stacking direction, the flow path is formed by an internal space where the back surfaces of the cooling surfaces face each other, and when the first cooling surface and the second cooling surface are in surface contact with the batteries, the first projection and the second projection face each other in the stacking direction inside the cooling section.

[0007] A method for manufacturing a battery pack according to the present invention is a method for manufacturing a battery pack equipped with a cooler according to the above invention, wherein a cooling device formed by a plurality of coolers such that the cooling surfaces of the coolers face each other is installed inside a case that houses a plurality of battery cells, and the method includes an insertion step of inserting the battery cells between adjacent coolers, and a deformation step of deforming the coolers after the battery cells have been inserted between the coolers by increasing the internal pressure of the coolers so that the cooling surfaces come into contact with the battery cells, wherein, inside the coolers before deformation in the insertion step, the first projection and the second projection do not face each other in the stacking direction, and inside the coolers after deformation in the deformation step, the first projection and the second projection face each other in the stacking direction. [Effects of the Invention]

[0008] In this invention, it is possible to prevent the cooling liquid flow path from being crushed by the battery expanding during use, thereby ensuring cooling performance. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing the battery pack in the embodiment. [Figure 2] This is a diagram illustrating a cooling system. [Figure 3] This is a diagram illustrating a condenser. [Figure 4] This is a diagram illustrating the cooling system. [Figure 5] Figure 5(a) is a diagram illustrating the shape in the extruded state, Figure 5(b) is a diagram illustrating the shape during deformation when pressure is applied inside the cooler, and Figure 5(c) is a diagram illustrating the shape after deformation when pressure is applied inside the cooler. [Figure 6] This diagram illustrates how, during use, the battery cells expand, causing their protrusions to support each other within the cooling section. [Figure 7] Figure 7(a) is a diagram illustrating the insertion process, Figure 7(b) is a diagram illustrating the deformation process in progress, and Figure 7(c) is a diagram illustrating the state after the deformation process is completed. [Figure 8] Figure 8(a) is a diagram illustrating a structure in which the corner has a thin-walled section, Figure 8(b) is a diagram illustrating another shape of the thin-walled section, and Figure 8(c) is a diagram illustrating yet another shape of the thin-walled section. [Modes for carrying out the invention]

[0010] The following describes in detail the methods for manufacturing the cooler and battery pack according to embodiments of the present invention. However, the present invention is not limited to the embodiments described below.

[0011] Figure 1 is a schematic diagram of a battery pack in an embodiment. The battery pack 1 comprises a plurality of battery cells 2, a case 3, and a cooling device 4. The battery pack 1 is mounted on an electric vehicle. The electric vehicle equipped with the battery pack 1 runs by supplying the power stored in the battery pack 1 to a motor for driving.

[0012] The battery cell 2 is a battery formed in the shape of a rectangular parallelepiped. The battery cell 2 includes a flat surface 2a with the largest surface area. The battery cell 2 is placed inside the case 3 with the flat surface 2a facing the X direction. The X direction is the first direction. Inside the case 3, multiple battery cells 2 are stacked in the X direction.

[0013] Case 3 houses the battery cells 2 and the cooling device 4. Inside Case 3, multiple battery cells 2 constitute a battery module. Case 3 is a battery pack case that houses multiple battery modules.

[0014] The cooling device 4 cools the battery cells 2 with a cooling liquid. The cooling device 4 comprises a plurality of coolers 20 and a pair of pipes 30.

[0015] The coolers 20 are stacked alternately with the battery cells 2 to cool the battery cells 2. The coolers 20 are made of extruded metal. The coolers 20 extend in the Y direction. The coolers 20 have a cooling surface 20a that contacts the battery cells 2. As shown in Figure 2, the cooling device 4 is an integral structure in which a plurality of coolers 20 are joined to a pair of pipes 30, and the coolers 20 have a structure in which their cooling surfaces 20a face each other. The coolers 20 are configured to be deformable so that their thickness in the X direction increases. Figure 2 shows the cooler 20 before deformation, with its thickness in the X direction remaining thin. Figure 1 shows the cooler 20 after deformation, with its thickness in the X direction increased. The coolers 20 are manufactured in a thinner state than when in use and brazed to the pipes 30.

[0016] As shown in FIG. 1, in the completed state of the battery pack 1, a laminate is formed inside the case 3 in which a plurality of coolers 20 and a plurality of battery cells 2 are alternately stacked in the X direction, and the coolers 20 are located at both ends in the stacking direction of the laminate. The stacking direction is the same as the X direction. Since the battery cell 2 is rectangular and the cooler 20 is flat, one battery cell 2 is sandwiched between two coolers 20. The battery cell 2 and the cooler 20 are stacked such that the surfaces with the largest area among the plurality of surfaces are in contact. The cooling surface 20a contacts the flat surface 2a of the battery cell 2. The cooling surface 20a includes a first cooling surface that contacts one of the adjacent battery cells 2 and a second cooling surface that contacts the other of the adjacent battery cells 2.

[0017] The cooler 20 has a cooling part 21 and a connection part 22.

[0018] The cooling part 21 is disposed between adjacent battery cells 2 in the stacking direction. The cooling part 21 is a part that includes the cooling surface 20a. As shown in FIG. 3, the cooling part 21 is a hollow plate member. Inside the cooling part 21, a flow path 23 through which a coolant flows is provided. The internal space of the cooling part 21 is the flow path 23 of the coolant. The flow path 23 is formed by an internal space in which the back surfaces of the cooling surfaces 20a face each other. The cooling part 21 forms a laminate together with the battery cells 2. As shown in FIG. 1, in the state where the cooling device 4 is housed in the case 3, the cooling part 21 extends in the Y direction orthogonal to the X direction. The Y direction is the second direction.

[0019] The connection part 22 is formed at both ends of the cooling part 21 and is connected to the pipe 30. In the cooling device 4, the coolers 20 are arranged such that the cooling surfaces 20a face each other, and the connection parts 22 of the coolers 20 are joined to the pipe 30.

[0020] The pipe 30 is a rectangular pipe extending in the X direction. The pipe 30 is made of extruded metal. Multiple coolers 20 are connected to the pipe 30. The pipe 30 has multiple connection ports 31. The connection ports 31 are openings that open in the Y direction. The pipe 30 is formed by extrusion molding, and the connection ports 31 are opened by machining. The connection portions 22 of the coolers 20 are connected to the connection ports 31. The coolers 20 and the pipe 30 are joined when the connection portions 22 are fitted into the connection ports 31.

[0021] A first end cap 32 and a second end cap 33 are joined 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. In the pair of pipes 30, a first pipe section 34 is joined to one of the first end caps 32, and a second pipe section 35 is joined to the other first end cap 32. The first pipe section 34 is the inlet pipe section. 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 outlet pipe section. Coolant discharged from the cooling device 4 flows out to the outside of the cooling device 4 from the second pipe section 35.

[0022] In the cooling device 4, the cooling section 21 is deformable such that the cooling surface 20a is displaced in the X direction according to the pressure inside the cooler 20. The cooling section 21 has a deformable section 21a. The deformable section 21a is the part that deforms so that the thickness of the cooling section 21 in the X direction increases. As shown in Figure 3, the deformable section 21a is formed in a shape that is inclined with respect to the X direction.

[0023] Figure 4 is a diagram illustrating the cooling section. Note that Figure 4 shows the state before deformation of the deformed section 21a, that is, the shape of the cooler 20 as it was extruded.

[0024] The cooling section 21 has a parallelogram shape in its as-extruded form. The cooling section 21 has projections 21b that protrude in the stacking direction from the back surface of the cooling surface 20a. The projections 21b are a structure for securing internal space in the cooling section 21 when in use. Inside the cooling section 21, a pair of projections 21b are provided on the inner surfaces facing each other in the stacking direction. The projections 21b include a first projection that protrudes in the stacking direction from the back surface of one cooling surface 20a toward the back surface of the other cooling surface 20a, and a second projection that protrudes in the stacking direction from the back surface of the other cooling surface 20a toward the back surface of the first cooling surface 20a. In the as-extruded form, the pair of projections 21b in the cooling section 21 are arranged in a staggered pattern.

[0025] In its pre-deformation state, the deformed portion 21a is inclined with respect to the cooling surface 20a. At both ends of the pre-deformation deformed portion 21a, one corner 21c between the deformed portion 21a and the cooling surface 20a is formed at an obtuse angle, while the other corner 21d between the deformed portion 21a and the cooling surface 20a is formed at an acute angle.

[0026] In the cooling section 21, the cooling surface 20a extends along the Z direction before and after deformation. In other words, as the deformation of the deformable section 21a occurs, the cooling surface 20a maintains its position along the Z direction, causing the cooling section 21 to deform in such a way that it becomes thicker in the X direction.

[0027] As shown in Figure 5(a), before deformation of the deformable portion 21a, the thickness of the cooling portion 21 in the X direction is thin. As shown in Figure 5(b), while the deformable portion 21a is being deformed, the thickness of the cooling portion 21 in the X direction becomes thicker than before deformation. As shown in Figure 5(c), after deformation of the deformable portion 21a, the thickness of the cooling portion 21 in the X direction is thick. When both cooling surfaces 20a are in surface contact with the flat surface 2a of the battery cell 2, the pair of protrusions 21b face each other in the stacking direction inside the cooling portion 21. After deformation due to the application of internal pressure, the Z-direction positions of the pair of protrusions 21b of the cooler 20 are aligned. In the deformed state, the deformable portion 21a is perpendicular to the cooling surface 20a. The deformed cooling portion 21 has a rectangular outer shape.

[0028] As shown in Figure 6, when the battery cell 2 expands and the cooling surface 20a deforms so that the internal space of the cooling section 21 narrows, the pair of protrusions 21b are in contact with each other inside the cooling section 21, with the back surfaces of one cooling surface 20a separated from the back surface of the other cooling surface 20a. When the pair of protrusions 21b are in contact with each other, the load acting from the battery cell 2 on the cooling surface 20a is supported by the pair of protrusions 21b, 21b to prevent the flow path 23 from being crushed and blocked. The cooling section 21 is shaped such that once it is deformed to expand, the pair of protrusions 21b support each other, preventing it from returning to its thin state. Even if the battery cell 2 expands during use, the support provided by the pair of protrusions 21b inside the cooling section 210 prevents the flow path 23 from being crushed and blocked.

[0029] The manufacturing method for the battery pack 1 includes a joining step, an installation step, an insertion step, and a deformation step. In this manufacturing method, after assembling the battery cells 2 to the cooler 20, the cooler 20 is expanded by applying internal pressure to the cooler 20, causing the cooler 20 and the battery cells 2 to be in close contact.

[0030] The joining process involves joining multiple coolers 20 to a pair of pipes 30. In the joining process, a cooling device 4 is formed as a single integrated structure, and the components of the cooling device 4 are joined together so that the coolers 20 face each other on the cooling surface 20a. The cooling device 4 shown in Figure 2 is formed by the joining process.

[0031] The installation process involves installing the integrated cooling device 4 inside the case 3. In the installation process, the integrated cooling device 4 is installed inside the case 3 while the battery cells 2 are not yet installed.

[0032] The insertion process involves inserting the battery cells 2 between the coolers 20. In the insertion process, with the cooling device 4, which is formed so that the coolers 20 face each other with their cooling surfaces 20a, installed inside the case 3, the battery cells 2 are inserted between adjacent coolers 20. Before inserting the battery cells 2, the coolers 20 are thin. The coolers 20 are extruded into this thin shape.

[0033] As shown in Figure 7(a), in the insertion step, with the cooler 20 in an undeformed state, the battery cell 2 is positioned in a location where the flat surface 2a and the cooling surface 20a do not come into contact within the space where the cooling surfaces 20a face each other. The insertion step includes the step of positioning the battery cell 2 in a location where the battery cell 2 and the cooler 20 do not come into contact with each other, with the cooler 20 in an undeformed state. When inserting the battery cell 2, a clearance exists between the cooler 20 and the battery cell 2. Inside the cooler 20 before deformation in the insertion step, as shown in Figures 7(a) and 5(a), the pair of protrusions 21b do not face each other in the stacking direction.

[0034] The deformation process involves increasing the internal pressure of the cooler 20 to expand the cooling section 21. In the deformation process, after the battery cells 2 are inserted between the coolers 20, the internal pressure of the cooler 20 is increased to deform the cooler 20 so that the cooling surface 20a comes into contact with the battery cells 2.

[0035] As pressure is applied to the inside of the cooler 20 during the deformation process, the cooler 20 begins to expand, as shown in Figure 7(b). When pressure is applied to the inside of the cooler 20 during the deformation process, the cooler 20 becomes fully expanded, as shown in Figure 7(c). Inside the cooler 20 after deformation during the deformation process, the pair of protrusions 21b are facing each other in the stacking direction and spaced apart, as shown in Figures 7(c) and 5(c).

[0036] The deformation process also includes a step of bringing the cooling surface 20a into contact with the battery cell 2 to form a laminate in which the cooler 20 and the battery cell 2 are stacked, and a step of compressing the battery cell 2 with the cooler 20 in the stacking direction of the laminate.

[0037] For example, in the deformation process, after the cooling device 4 is placed inside the case 3, the second pipe section 35 side is closed with a valve or the like, and the coolant inside the cooler 20 is supplied from the first pipe section 34 side by a pump or the like, applying pressure inside the cooler 20. As the pressure inside the cooler 20 increases, the deformation section 21a is deformed so that the flow path 23 inside the cooler 20 widens 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 the deformation process, the cooler 20 is deformed so that the cooling surface 20a comes into contact with the flat surface 2a of the battery cell 2. After the battery cell 2 is inserted into the space between the opposing cooling surfaces 20a, the coolant is supplied from the pump to the first pipe section 34, increasing the pressure inside the cooler 20. As the pressure inside the cooler 20 increases and the cooling section 21 deforms to increase its thickness in the X direction, the cooling surface 20a can be brought into close contact with the flat surface 2a. The deformation process involves bringing the cooling surface 20a into contact with the battery cell 2 to form a laminate in which the cooler 20 and the battery cell 2 are stacked, and compressing the battery cell 2 in the stacking direction of the laminate with the cooler 20.

[0038] As described above, according to this embodiment, even if the battery cell 2 expands during use, the pair of protrusions 21b provided inside the cooling unit 21 prevent the flow path 23 from collapsing completely. This ensures that the flow path cross-sectional area of ​​the flow path 23 is maintained and that cooling performance is ensured.

[0039] The number of battery cells 2 is not particularly limited. The number of battery cells 2 stacked in the X direction is not limited. A structure in which multiple battery cells 2 are arranged side by side in the Y direction is also possible.

[0040] Furthermore, in the cooling section 21, the thickness of the corners 21c and 21d may be thinner than that of other parts. When the inside of the extruded cooler 20 is pressurized, the cooler 20 deforms while maintaining its parallelogram shape, so that the corners 21c and 21d are made weaker by providing thin-walled sections. As shown in Figure 8(a), the corner 21c is formed by a thin-walled section extending along the deformed section 21a. The corner 21c is thinner than the deformed section 21a. The shape of the thin-walled section is not particularly limited. As shown in Figure 8(b), the corner 21c may be formed by a thin-walled section extending along the Z direction. Alternatively, as shown in Figure 8(c), the corner 21c may be formed by a thin-walled section extending along the X direction. [Explanation of symbols]

[0041] 1 Battery pack 2 battery cells 2a flat surface 3 cases 4 Cooling device 20 Cooler 20a cooling surface 21 Cooling section 22 Connection part 23 Flow channels 30 pipes

Claims

1. A cooler that is stacked alternately with batteries and cools the batteries, It has a cooling section positioned between adjacent batteries in the stacking direction, The cooling unit is The flow path through which the coolant flows, A first cooling surface which is a cooling surface that contacts one of the aforementioned batteries, A second cooling surface which is a cooling surface that contacts the other of the two batteries, A first projection extending from the back surface of the first cooling surface toward the back surface of the second cooling surface in the stacking direction, It has a second projection that protrudes in the stacking direction from the back surface of the second cooling surface toward the back surface of the first cooling surface, The aforementioned flow path is formed by an internal space where the back surfaces of the cooling surfaces face each other. When the first cooling surface and the second cooling surface are in surface contact with the battery, the first projection and the second projection face each other in the stacking direction inside the cooling section. A cooler characterized by the following features.

2. If the battery expands and the cooling surface deforms so that the internal space narrows, the first projection and the second projection are in contact with each other inside the cooling section, with the back surfaces of the first cooling surface and the second cooling surface separated. The cooler according to feature 1.

3. When the first projection and the second projection are in contact, the load acting from the battery on the cooling surface is received by the first projection and the second projection so that the flow path is not crushed and blocked. The cooler according to feature 2.

4. A method for manufacturing a battery pack equipped with a cooler according to any one of claims 1 to 3, With a cooling device formed by a plurality of coolers such that the cooling surfaces of the coolers face each other, installed inside a case that houses a plurality of battery cells, the insertion step involves inserting the battery cells between adjacent coolers, After the battery cells are inserted between the coolers, a deformation step is performed to deform the coolers by increasing the internal pressure of the coolers so that the cooling surface comes into contact with the battery cells. Includes, In the interior of the cooler before deformation during the insertion process, the first projection and the second projection are not facing each other in the stacking direction. In the interior of the cooler after deformation in the deformation process, the first projection and the second projection face each other in the stacking direction. A method for manufacturing a battery pack characterized by the following:

5. The insertion step includes the step of arranging the battery cell inside the case in a position where the battery cell and the cooling surface do not come into contact, while the cooler is not deformed. The deformation step includes bringing the cooling surface into contact with the battery cell to form a laminate in which the cooler and the battery cell are stacked, and compressing the battery cell in the stacking direction of the laminate with the cooler. In the interior of the cooler after deformation in the deformation process, the first projection and the second projection are separated. The method for manufacturing a battery pack according to claim 4.

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