Battery pack manufacturing method

Abstract

The invention relates to a method for manufacturing a battery pack. The method for manufacturing a battery pack includes a molding step for molding a case that accommodates a battery, the molding step including: a step for bringing the bottom of a lower case into a flat plate shape by bringing the bottom into close contact with a jig; and a step for adhering the cooler to the lower surface of the lower case in a state in which the bottom of the lower case is brought into close contact with the jig.

Description

TECHNICAL FIELD

[0001] The present application relates to a manufacturing method of a battery pack. BACKGROUND

[0002] In Japanese Patent Application Publication No. 2023-046659, a battery pack provided with a case that houses a battery and a cooler that cools the battery is disclosed. In the structure described in Japanese Patent Application Publication No. 2023-046659, a plate-shaped cooler is arranged outside the case and is adhered to the lower surface of the case. SUMMARY

[0003] However, the case of the battery pack is sometimes formed by press working. However, if the case becomes large, it is difficult to perform press working on the bottom of the case with high flatness. In the case where the bottom of the case having a concave-convex is coated with an adhesive, the adhesive that coats only the concave-convex causes the layer of the adhesive to become thick. Therefore, in the structure where the cooler is adhered to the lower surface of the case as in the structure described in Japanese Patent Application Publication No. 2023-046659, since there is a portion where the adhesive is thick, the thermal resistance becomes large, and the cooling performance decreases.

[0004] The present application provides a manufacturing method of a battery pack that is capable of joining a plate-shaped member to the bottom of a case in a state where the flatness of the case is good.

[0005] The manufacturing method of the battery pack of the present application includes a forming process of forming a case that houses a battery, characterized by,

[0006] the forming process includes:

[0007] a first process in which the bottom of the case is brought into close contact with a jig so that the bottom becomes a flat plate; and

[0008] a second process in which a plate-shaped member is joined to the lower surface of the case in a state where the bottom of the case is in close contact with the jig.

[0009] In the present application, a plate-shaped member can be joined to the bottom of a case in a state where the flatness of the case is good. BRIEF DESCRIPTION OF DRAWINGS

[0010] Features, advantages, and technical and industrial significance of exemplary embodiments of the present application will be described below with reference to the accompanying drawings, wherein the same reference numerals in different drawings denote the same element, and wherein:

[0011] Figure 1 is a view for explaining a manufacturing method of a battery pack in an embodiment;

[0012] Figure 2 is a view for explaining a manufacturing method of a battery pack in a case where vacuum suction is used;

[0013] Figure 3 is a drawing for explaining a manufacturing method of a battery pack in a case where a plate-like member is a protection member. DETAILED DESCRIPTION

[0014] Hereinafter, a manufacturing method of a battery pack in an embodiment of the present application will be specifically described. Note that the present application is not limited to the following described embodiment.

[0015] Figure 1 is a drawing for explaining a manufacturing method of a battery pack in an embodiment. The battery pack 1 is provided with a battery 2, a case 3 that houses the battery 2, and a cooler 4 that cools the battery 2. The case 3 includes an upper case and a lower case 5. The cooler 4 is provided outside the case 3 and engages with a lower surface 5a of the lower case 5. The lower surface 5a of the lower case 5 is a lower surface of the case 3. A flow path through which a coolant for cooling a battery cell flows is provided inside the cooler 4. The battery cell is cooled by the coolant flowing inside the cooler 4. Note that, Figure 1 shows a cross section of the battery pack 1.

[0016] The manufacturing method of the battery pack 1 includes a molding process of molding the case 3 (processes S1 to S3) and a setting process of setting the battery 2 inside the molded case 3 (process S4).

[0017] The molding process includes a process of making the bottom 5b of the lower case 5 into a flat plate shape using a jig 10 (processes S1 to S2) and a process of engaging the cooler 4 with the lower surface 5a of the lower case 5 (process S3).

[0018] Specifically, first, the lower case 5 after press working is placed on the jig 10 (process S1). The case 3 is a metal case. For example, the lower case 5 is made of iron. In a large case 3, since the bottom 5b of the lower case 5 also becomes large, there is a case where the flatness of the bottom 5b is poor in the lower case 5 after press working. After press working, the bottom 5b of the lower case 5 is deformed (including a concave-convex shape). The jig 10 is formed in the same shape as a press die. The jig 10 includes an electromagnet and has a flat-shaped suction surface 10a. For example, the jig 10 is a jig in which an electromagnet is installed. The jig 10 can generate a magnetic force from the electromagnet by energization of the electromagnet. In process S1, the electromagnet of the jig 10 is turned off, and the lower case 5 is placed on the jig 10 in a manner that the lower surface 5a of the lower case 5 faces upward. In a state where the lower case 5 is placed on the jig 10, the inner surface of the bottom 5b faces the suction surface 10a. Note that, in the case where the lower case 5 is made of iron, the bottom 5b of the lower case 5 is attracted to the suction surface 10a of the jig 10 by the magnetic force of the electromagnet. Figure 1 shows a cross section of the jig 10.

[0019] Next, the bottom 5b of the lower case 5 is brought into close contact with the jig 10 (step S2). In step S2, the electromagnet included in the jig 10 is energized to generate a magnetic force, and the bottom 5b of the lower case 5 is attracted to the attraction surface 10a of the jig 10 by the magnetic force generated by the electromagnet. The jig 10 including the electromagnet is capable of generating a magnetic force that attracts the bottom 5b of the lower case 5 to the attraction surface 10b by energization. In step S2, the electromagnet included in the jig 10 is in an on state, and the bottom 5b of the lower case 5 is in a state of being magnetically attracted to the jig 10. The state of magnetically attracting the bottom 5b to the jig 10 is a state in which the flatness of the bottom 5b is temporarily improved. That is, in step S2, if the electromagnet is returned from the on state to the off state, the shape of the bottom 5b returns from the flat shape shown in step S2 to the uneven shape shown in step S1.

[0020] Next, in the state in which the bottom 5b of the lower case 5 is in close contact with the jig 10, the cooler 4 is joined to the lower surface 5a of the lower case 5 (step S3). In step S3, in the state in which the bottom 5b of the lower case 5 is magnetically attracted to the jig 10 (the state in which the flatness of the bottom 5b is temporarily improved), the cooler 4 is adhered to the lower surface 5a of the lower case 5 via the adhesive 6. The adhesive 6 is a joining member for joining the plate-shaped member to the lower surface 5a of the lower case 5. For example, the adhesive 6 is composed of a thermally conductive adhesive. The cooler 4 is a plate-shaped member that is joined to the lower surface 5a of the lower case 5. The cooler 4 includes a flat plate portion that faces the lower surface 5a of the lower case 5.

[0021] For example, in step S3, the adhesive 6 is applied to the lower surface 5a of the lower case 5, and the flat plate portion of the cooler 4 is adhered to the lower surface 5a from above the adhesive 6. After the adhesion, a sandwiched panel structure in which the bottom 5b of the lower case 5, the adhesive 6, and the cooler 4 are stacked is formed, and thus the bottom 5b side of the lower case 5 becomes high in rigidity. Thus, even if the state in which the bottom 5b is in close contact with the jig 10 is released, the flatness of the bottom 5b does not deteriorate. That is, even if the close contact with the jig 10 is released, the shape of the bottom 5b does not return to the uneven shape shown in step S1, and the state in which the flatness of the bottom 5b is good can be maintained. In this way, step S3 includes a step of stopping the energization after the adhesion of the cooler 4 and bringing the jig 10 into a state in which the electromagnet is off, and releasing the state in which the bottom 5b is in close contact with the jig 10. If the electromagnet is turned off before the cooler 4 is adhered to the lower surface 5a via the adhesive 6, the shape of the bottom 5b returns from the flat shape shown in step S2 to the uneven shape shown in step S1. Before this release, the cooler 4 is adhered to the lower surface 5a by the adhesive 6 in step S3.

[0022] Further, in the process S3, the adhesive 6 is applied to the lower surface 5a in a state in which the flatness of the bottom 5b is temporarily good by the magnetic attraction, and thus the adhesive 6 is thinned, the cooling performance is improved, and the adhesive 6 is reduced, and the cost is reduced. If the adhesive 6 is applied to the inner surface of the bottom 5b in a state in which the shape of the bottom 5b is the concave-convex shape shown in the process S1, the adhesive 6 is applied so as to fill only the concave-convex of the inner surface of the bottom 5b. In this case, since there is a portion in which the adhesive 6 is thick, the thermal resistance is increased, the cooling performance is deteriorated, and a large amount of the adhesive 6 is required, and the cost is increased.

[0023] Next, the battery 2 is disposed inside the lower case 5 (process S4). In the process S4, the battery cell of the battery 2 is adhered to the inner surface of the bottom 5b of the lower case 5 via the adhesive 7. The adhesive 7 is composed of a thermally conductive adhesive. For example, the adhesive 7 is applied to the inner surface of the bottom 5b of the lower case 5, and the lower surface of the battery cell is adhered to the inner surface of the bottom 5b from above the adhesive 7. In the process S4, since the flatness of the bottom 5b is maintained in a good state by the sandwiched panel structure, by applying the adhesive 7 to the bottom 5b in this state, the adhesive 7 is thinned, the cooling performance is improved, and the adhesive 7 is reduced, and the cost is reduced. If the adhesive 7 is applied to the inner surface of the bottom 5b in a state in which the shape of the bottom 5b is the concave-convex shape shown in the process S1, the adhesive 7 is applied so as to fill only the concave-convex of the inner surface of the bottom 5b. In this case, since there is a portion in which the adhesive 7 is thick, the thermal resistance is increased, the cooling performance is deteriorated, and a large amount of the adhesive 7 is required, and the cost is increased.

[0024] As described above, according to the embodiment, in a state in which the flatness of the bottom 5b of the lower case 5 is temporarily good by the magnetic attraction, the sandwiched panel structure composed of the bottom 5b, the adhesive 6, and the cooler 4 is formed. Thus, even if the close contact with the jig 10 is released, the flatness of the bottom 5b can be maintained in a good state.

[0025] Note that, although the method of the magnetic attraction to the jig 10 is described, the method of manufacturing the battery pack 1 is not limited thereto. The method of bringing the bottom 5b into close contact with the jig is not limited to the magnetic attraction, and can be the vacuum attraction.

[0026] As Figure 2As shown, the manufacturing method of the battery pack 1 using vacuum suction includes a step of bringing the lower case 5 into close contact with the jig 20. The jig 20 is formed in the same shape as the press die. The jig 20 has a suction surface 20a in a planar shape and a vacuum circuit 20b. The vacuum circuit 20b is constituted by a pipe, for example. The manufacturing method of the battery pack 1 using the jig 20 includes a molding step (steps Sll to S13) of molding the case 3 and a setting step (step S14) of setting the battery 2 inside the molded case 3. The molding step includes a step (steps Sll to S12) of bringing the bottom portion 5b of the lower case 5 into a flat plate shape using the jig 20 and a step (step S13) of joining the cooler 4 to the lower surface 5a of the lower case 5. Note that the step S14 is the same as the step S4, and thus the description is omitted. In addition, in the Figure 2 A cross section of the jig 20 is shown in FIG. 12.

[0027] First, the lower case 5 after press working is placed on the jig 20 (step Sll). The jig 20 is capable of vacuum suction when vacuuming from the vacuum circuit 20b is started. In the step Sll, the vacuum of the jig 20 is closed, and the lower case 5 is placed on the jig 20 in a manner that the lower surface 5a of the lower case 5 faces upward.

[0028] Next, the bottom portion 5b of the lower case 5 is brought into close contact with the jig 20 (step S12). In the step S12, the vacuum of the jig 20 is started, and the bottom portion 5b of the lower case 5 is suctioned to the suction surface 20a of the jig 20 by vacuum suction. The state of suctioning the bottom portion 5b to the jig 20 is a state of temporarily improving the flatness of the bottom portion 5b. In the step S12, it is assumed that the state of starting the vacuum returns to the state of closing, and the shape of the bottom portion 5b returns from the flat plate shape shown in the step S12 to the concave-convex shape shown in the step Sll.

[0029] Next, the cooler 4 is joined to the lower surface 5a of the lower case 5 in the state of bringing the bottom portion 5b of the lower case 5 into close contact with the jig 20 (step S13). In the step S13, the cooler 4 is adhered to the lower surface 5a of the lower case 5 via the adhesive 6 in the state of suctioning the bottom portion 5b of the lower case 5 to the jig 20 (the state of temporarily improving the flatness of the bottom portion 5b).

[0030] Thus, the same effects as the manufacturing method of the battery pack 1 using magnetic suction can be obtained for the manufacturing method of the battery pack 1 using vacuum suction shown in FIG. 12. Figure 2

[0031] In addition, the plate-shaped member adhered to the lower surface 5a of the lower case 5 is not limited to the cooler 4. The plate member is not limited to the cooler 4, and can be a cover that protects the case 3.

[0032] As​Figure 3 The manufacturing method of the battery pack 1 in the case where the plate-like member is the protection member includes a process of bonding the common panel 8 to the lower surface 5a of the lower case 5. The battery pack 1 has a structure in which the common panel 8 is bonded to the lower surface 5a of the lower case 5. The common panel 8 is a protection member that protects the case 3 and is a plate-like protection cover that covers the lower surface 5a of the lower case 5. The manufacturing method of the battery pack 1 including the common panel 8 includes a molding process (processes S21 to S23) of molding the case 3 and a process (process S24) of disposing the battery 2 inside the molded case 3. The molding process includes a process (processes S21 to S22) of making the bottom portion 5b of the lower case 5 flat using the jig 10 and a process (process S23) of joining the common panel 8 to the lower surface 5a of the lower case 5. Note that the processes S21 to S22 are the same as the processes S1 to S2, and thus the description thereof is omitted. In addition, the cross section of the battery pack 1 is shown in FIG. 8. Figure 3

[0033] In the process S23, the common panel 8 is joined to the lower surface 5a of the lower case 5 in a state in which the bottom portion 5b of the lower case 5 is in close contact with the jig 10. The common panel 8 is bonded to the lower surface 5a via the adhesive 6 in a state in which the bottom portion 5b is magnetically attracted to the jig 10. The common panel 8 includes a flat portion that faces the lower surface 5a of the lower case 5. After bonding, the bottom portion 5b of the lower case 5, the adhesive 6, and the common panel 8 become a sandwiched panel structure, and thus the bottom portion 5b of the lower case 5 becomes highly rigid. Thus, even if the state in which the bottom portion 5b is in close contact with the jig 10 is released, the flatness of the bottom portion 5b does not deteriorate. The process S23 includes a process of stopping the energization after bonding to the cooler 4 and placing the jig 10 in a state in which the electromagnet is off, and releasing the state in which the bottom portion 5b is in close contact with the jig 10.

[0034] Next, the battery 2 is disposed inside the lower case 5 (process S24). In the process S24, the battery cell of the battery 2 is placed on the bottom portion 5b of the lower case 5. Since the flatness of the bottom portion 5b is maintained in a good state by the sandwiched panel structure, the battery 2 is housed in the case 3. If the battery 2 is placed inside the case 3 in a state in which the shape of the bottom portion 5b is the concave-convex shape shown in the process S21, the flatness of the bottom portion 5b is poor, and sometimes the battery 2 cannot be housed in the case 3. In this case, the case 3 must be made larger so that the battery 2 can be housed even if the flatness of the bottom portion 5b is poor. That is, the energy density of the battery pack 1 becomes small.

[0035] Thus, according to the manufacturing method of the battery pack 1 having the common panel 8 shown in Figure 3 , it is possible to prevent the energy density of the battery pack 1 from becoming small.

[0036] ​In addition, the method of joining the cooler 4, the common panel 8, and the lower surface 5a of the lower case 5 is not limited to adhesion. The joining method of the plate-shaped members can also be adhesion, welding, friction stir joining, or mechanical fastening.

[0037] In addition, the battery 2 can be a battery module in which a plurality of battery cells are combined, or can also be a plurality of battery cells in a state that is not modularized. That is, the battery pack 1 can be a battery pack in which a battery module that is the battery 2 is housed in the case 3, or can also be a battery pack in which a plurality of battery cells that are the battery 2 are directly housed in the case 3.

Claims

1. A method of manufacturing a battery pack, comprising a forming process of forming a case that houses a battery, wherein the forming process includes: a first process in which a bottom of the case is brought into close contact with a jig so that the bottom becomes a flat plate; and a second process in which a plate-shaped member is joined to a lower surface of the case in a state in which the bottom of the case is in close contact with the jig.

2. The method of manufacturing a battery pack according to claim 1, wherein the second process includes a process of joining a cooling member or a protection member as the plate-shaped member to the lower surface of the case.

3. The method of manufacturing a battery pack according to claim 2, wherein the first process includes a process of generating a magnetic force by energization from an electromagnet included in the jig, and adsorbing the bottom of the case made of metal to an adsorption surface of the jig by the magnetic force generated by the electromagnet.

4. The method of manufacturing a battery pack according to claim 2, wherein the first process includes a process of performing vacuuming from a vacuuming circuit provided to the jig, and adsorbing the bottom of the case to the adsorption surface of the jig by the vacuuming from the vacuuming circuit.

5. The method of manufacturing a battery pack according to claim 3 or 4, wherein the second process includes a process of adhering the plate-shaped member to the lower surface of the case via an adhesive, as the process of joining the plate-shaped member to the lower surface of the case.

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