Method for manufacturing battery pack

Abstract

To provide a manufacturing method of a battery pack capable of joining a plate-like member to a bottom part of a case with good flatness.SOLUTION: The method for manufacturing the battery pack 1 includes a forming step (steps S1 to S3) of forming the case 3 that houses the battery 2, and the forming step includes a step (step S2) of bringing the bottom side 5b of the lower case 5 into close contact with the jig 10 to form the bottom side 5b into a flat plate shape, and a step (step S3) of bonding the coolers 4 to the lower side 5b of the lower case 5 in a state where the bottom side 5a of the lower case 5 is in close contact with the jig 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a battery pack that includes a case that houses a battery and a cooler that cools the battery. In the configuration described in Patent Document 1, the plate-shaped cooler is placed outside the case and adhered to the underside of the case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-046659 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, battery pack cases are sometimes formed by press working. However, as the case becomes larger, it becomes difficult to press the bottom of the case with high flatness. When applying adhesive to the bottom of a case with unevenness, the adhesive is applied only to fill the unevenness, resulting in a thick adhesive layer. Therefore, in a structure in which a cooler is attached to the bottom of the case, as in the configuration described in Patent Document 1, there are areas where the adhesive is thick, which increases thermal resistance and reduces cooling performance.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a method for manufacturing a battery pack that can join a plate-like member to the bottom of a case that has good flatness. [Means for solving the problem]

[0006] The present invention is a method for manufacturing a battery pack, which includes a molding step of molding a case that houses a battery, and is characterized in that the molding step includes a first step of closely adhering the bottom of the case to a jig to make the bottom flat, and a second step of joining a plate-shaped member to the underside of the case while the bottom of the case is closely adhering to the jig. [Effects of the Invention]

[0007] In the present invention, the plate-like member can be joined to the bottom of the case, which is in a state of good flatness. [Brief explanation of the drawings]

[0008] [Figure 1] 5A to 5C are diagrams for explaining a manufacturing method of a battery pack according to an embodiment. [Figure 2] 10A and 10B are diagrams for explaining a manufacturing method of a battery pack when vacuum suction is used. [Figure 3] 10A to 10C are diagrams for explaining a method of manufacturing a battery pack when the plate-shaped member is a protective member. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a method for manufacturing a battery pack according to an embodiment of the present invention will be specifically described, although the present invention is not limited to the embodiment described below.

[0010] FIG. 1 is a diagram illustrating a manufacturing method of a battery pack according to an embodiment. The battery pack 1 includes 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 on the outside of the case 3 and is joined to the bottom surface 5a of the lower case 5. The bottom surface 5a of the lower case 5 is the bottom surface of the case 3. A flow path is provided inside the cooler 4 through which a coolant flows to cool the battery cells. The battery cells are cooled by the coolant flowing inside the cooler 4. Note that a cross section of the battery pack 1 is shown in FIG. 1.

[0011] The manufacturing method of the battery pack 1 includes a molding step of molding the case 3 (steps S1 to S3) and an installation step of installing the battery 2 inside the molded case 3 (step S4).

[0012] The molding process includes a step of forming the bottom portion 5b of the lower case 5 into a flat plate shape using a jig 10 (steps S1 and S2), and a step of joining the cooler 4 to the lower surface 5a of the lower case 5 (step S3).

[0013] Specifically, first, the pressed lower case 5 is placed on the jig 10 (step S1). The case 3 is a metal case. For example, the lower case 5 is made of iron. In a large case 3, the bottom 5b of the lower case 5 is also large, so the flatness of the bottom 5b of the pressed lower case 5 may be poor. The bottom 5b of the lower case 5 is distorted (including uneven shapes) after the press process. The jig 10 is formed in the same shape as the press mold. The jig 10 includes an electromagnet and has a flat attraction surface 10a. For example, the jig 10 is a jig with an electromagnet inside. When the jig 10 is energized, the electromagnet is turned on and a magnetic force can be generated from the electromagnet. In step S1, the electromagnet of the jig 10 is turned off, and the lower case 5 is placed on the jig 10 with the bottom surface 5a of the lower case 5 facing upward. When the lower case 5 is placed on the jig 10, the inner surface of the bottom portion 5b faces the suction surface 10a. Note that a cross section of the jig 10 is shown in FIG.

[0014] Next, the bottom 5b of the lower case 5 is brought into close contact with the jig 10 (step S2). In step S2, current is applied to the electromagnet included in the jig 10 to generate a magnetic force, and the magnetic force generated by the electromagnet attracts the bottom 5b of the lower case 5 to the attracting surface 10a of the jig 10. The jig 10, which includes an electromagnet, can generate a magnetic force by applying current so that the bottom 5b of the lower case 5 is attracted to the attracting surface 10b. In step S2, the electromagnet included in the jig 10 is turned on, and the bottom 5b of the lower case 5 is magnetically attracted to the jig 10. The state in which the bottom 5b is magnetically attracted to the jig 10 temporarily improves the flatness of the bottom 5b. In other words, if the electromagnet is returned from the on state to the off state in step S2, the shape of the bottom 5b returns from the flat shape shown in step S2 to the uneven shape shown in step S1.

[0015] Next, the cooler 4 is bonded to the underside 5a of the lower case 5 with the bottom 5b of the lower case 5 in close contact with the jig 10 (step S3). In step S3, the cooler 4 is bonded to the underside 5a of the lower case 5 via adhesive 6 with the bottom 5b of the lower case 5 magnetically attracted to the jig 10 (a state in which the flatness of the bottom 5b is temporarily improved). The adhesive 6 is a bonding member for bonding a plate-like member to the underside 5a of the lower case 5. For example, the adhesive 6 is made of a thermally conductive adhesive. The cooler 4 is a plate-like member bonded to the underside 5a of the lower case 5. The cooler 4 includes a flat plate portion facing the underside 5a of the lower case 5.

[0016] For example, in step S3, adhesive 6 is applied to the underside 5a of the lower case 5, and the flat portion of the cooler 4 is bonded to the underside 5a through the adhesive 6. After bonding, the bottom 5b of the lower case 5, the adhesive 6, and the cooler 4 are laminated to form a sandwich-like panel structure, making the bottom 5b side of the lower case 5 highly rigid. As a result, the flatness of the bottom 5b does not deteriorate even when the bottom 5b is released from the jig 10. In other words, even when the bottom 5b is released from the jig 10, the shape of the bottom 5b does not return to the uneven shape shown in step S1, and the flatness of the bottom 5b can be maintained in a good state. Thus, step S3 includes a step of turning off the power supply to the jig 10 after bonding the cooler 4, thereby releasing the bottom 5b from the jig 10. If the electromagnet is turned off before the cooler 4 is bonded to the lower surface 5a via the adhesive 6, the shape of the bottom 5b will return from the flat shape shown in step S2 to the uneven shape shown in step S1. Before the release, the cooler 4 is bonded to the lower surface 5a with the adhesive 6 in step S3.

[0017] Furthermore, in step S3, adhesive 6 is applied to underside 5a, which is temporarily flattened by magnetic attraction, so the adhesive 6 is thin, resulting in high cooling performance and less adhesive 6, resulting in lower costs. If adhesive 6 were applied to underside 5a when bottom 5b has the uneven shape shown in step S1, only enough adhesive 6 would be applied to fill in the unevenness of underside 5a. In this case, there would be thick areas of adhesive 6, which would increase thermal resistance and reduce cooling performance, and more adhesive 6 would be required, resulting in higher costs.

[0018] The battery 2 is then installed inside the lower case 5 (step S4). In step S4, the battery cells of the battery 2 are bonded to the inner surface of the bottom 5b of the lower case 5 via adhesive 7. The adhesive 7 is made of a thermally conductive adhesive. For example, adhesive 7 is applied to the inner surface of the bottom 5b of the lower case 5, and the underside of the battery cell is bonded to the inner surface of the bottom 5b over the adhesive 7. In step S4, the sandwich-like panel structure maintains the flatness of the bottom 5b. By applying adhesive 7 to the bottom 5b in this state, the adhesive 7 is thin, improving cooling performance and reducing the amount of adhesive 7, thereby reducing costs. If adhesive 7 were applied to the inner surface of the bottom 5b when the shape of the bottom 5b is uneven as shown in step S1, only enough adhesive 7 would be applied to fill the unevenness of the inner surface of the bottom 5b. In this case, the thick adhesive 7 would increase thermal resistance, reducing cooling performance, and requiring a large amount of adhesive 7, resulting in high costs.

[0019] As described above, according to the embodiment, the flatness of the bottom 5b of the lower case 5 is temporarily improved by magnetic attraction, and a sandwich panel structure is formed by the bottom 5b, adhesive 6, and cooler 4. This allows the flatness of the bottom 5b to remain good even when the adhesion to the jig 10 is released.

[0020] Although the method of magnetically adsorbing to the jig 10 has been described, the method of manufacturing the battery pack 1 is not limited to this. The method of tightly adhering the bottom 5b to the jig is not limited to magnetic adsorption, and may be vacuum adsorption.

[0021] As shown in FIG. 2, a manufacturing method of a battery pack 1 using vacuum suction includes a step of closely adhering a lower case 5 to a jig 20. The jig 20 is formed in the same shape as a press die. The jig 20 has a flat suction surface 20a and a vacuum circuit 20b. For example, the vacuum circuit 20b is configured with piping. A manufacturing method of a battery pack 1 using the jig 20 includes a molding step of molding the case 3 (steps S11 to S13) and an installation step of installing a battery 2 inside the molded case 3 (step S14). The molding step includes a step of flattening the bottom 5b of the lower case 5 using the jig 20 (steps S11 to S12) and a step of joining a cooler 4 to the underside 5a of the lower case 5 (step S13). Note that step S14 is similar to step S4, and therefore will not be described here. FIG. 2 also shows a cross section of the jig 20.

[0022] First, the pressed lower case 5 is placed on the jig 20 (step S11). The jig 20 can be vacuum-sucked when vacuuming from the vacuum circuit 20b is turned on. In step S11, the vacuuming of the jig 20 is turned off, and the lower case 5 is placed on the jig 20 with the lower surface 5a of the lower case 5 facing upward.

[0023] Next, the bottom 5b of the lower case 5 is brought into close contact with the jig 20 (step S12). In step S12, the vacuum of the jig 20 is turned on, and the bottom 5b of the lower case 5 is adsorbed to the adsorption surface 20a of the jig 20 by vacuum suction. The state in which the bottom 5b is adsorbed to the jig 20 by vacuum suction temporarily improves the flatness of the bottom 5b. If the vacuum suction is returned from the on state to the off state in step S12, the shape of the bottom 5b will return from the flat shape shown in step S12 to the uneven shape shown in step S11.

[0024] Next, the cooler 4 is bonded to the underside 5a of the lower case 5 with the bottom 5b of the lower case 5 in close contact with the jig 20 (step S13). In step S13, the cooler 4 is bonded to the underside 5a of the lower case 5 via the adhesive 6 with the bottom 5b of the lower case 5 being vacuum-adsorbed to the jig 20 (a state in which the flatness of the bottom 5b is temporarily improved).

[0025] In this way, the manufacturing method of the battery pack 1 using vacuum suction as shown in FIG. 2 can also provide the same effects as the manufacturing method of the battery pack 1 using magnetic suction.

[0026] Furthermore, the plate-like member bonded 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 may be a cover for protecting the case 3.

[0027] As shown in FIG. 3, a manufacturing method for a battery pack 1 in which a plate-shaped member is used as a protective member includes a step of adhering a shear panel 8 to the underside 5a of the lower case 5. The battery pack 1 has a structure in which the shear panel 8 is adhered to the underside 5a of the lower case 5. The shear panel 8 is a protective member that protects the case 3 and is a plate-shaped protective cover that covers the underside 5a of the lower case 5. A manufacturing method for a battery pack 1 including the shear panel 8 includes a molding step of molding the case 3 (steps S21 to S23) and an installation step of installing a battery 2 inside the molded case 3 (step S24). The molding step includes a step of flattening the bottom 5b of the lower case 5 using a jig 10 (steps S21 to S22) and a step of joining the shear panel 8 to the underside 5a of the lower case 5 (step S23). Note that steps S21 to S22 are similar to steps S1 to S2, and therefore will not be described here. A cross section of the battery pack 1 is also shown in FIG. 3.

[0028] In step S23, the shear panel 8 is joined to the underside 5a of the lower case 5 with the bottom 5b of the lower case 5 in close contact with the jig 10. With the bottom 5b magnetically attached to the jig 10, the shear panel 8 is bonded to the underside 5a via adhesive 6. The shear panel 8 includes a flat portion facing the underside 5a of the lower case 5. After bonding, the bottom 5b of the lower case 5, the adhesive 6, and the shear panel 8 form a sandwich-like panel structure, which gives the bottom 5b side of the lower case 5 high rigidity. This prevents deterioration of the flatness of the bottom 5b even when the bottom 5b is released from the close contact with the jig 10. Step S23 includes a step of turning off the power to the jig 10 after bonding the cooler 4, thereby releasing the close contact of the bottom 5b with the jig 10.

[0029] Then, the battery 2 is placed inside the lower case 5 (step S24). In step S24, the battery cell of the battery 2 is placed on the bottom 5b of the lower case 5. The sandwich panel structure keeps the flatness of the bottom 5b good, so the battery 2 fits inside the case 3. If the battery 2 is placed inside the case 3 when the bottom 5b has the uneven shape shown in step S21, the flatness of the bottom 5b may be poor and the battery 2 may not fit inside the case 3. In this case, the case 3 must be made larger so that the battery 2 can fit inside even if the flatness of the bottom 5b is poor. This means that the energy density of the battery pack 1 will be reduced.

[0030] In this way, according to the manufacturing method of the battery pack 1 having the shared panel 8 as shown in FIG. 3, it is possible to prevent the energy density of the battery pack 1 from becoming small.

[0031] Furthermore, the method of joining the cooler 4 and the shear panel 8 to the lower surface 5a of the lower case 5 is not limited to adhesive bonding. The plate-like members may be joined by adhesive bonding, welding, friction stir welding, or mechanical fastening.

[0032] The battery 2 may be a battery module made up of multiple battery cells, or multiple unmodularized battery cells. In other words, the battery pack 1 may be a battery module (battery 2) housed in the case 3, or multiple battery cells (battery 2) housed directly in the case 3. [Explanation of symbols]

[0033] 1 battery pack 2 batteries 3 cases 4 Cooler 5 Lower case 6,7 Adhesive 8 Share Panel 10,20 Jig 10a,20a Adsorption surface 20b Vacuum circuit

Claims

1. A method for manufacturing a battery pack including a molding step of molding a case that houses a battery, The molding step includes: a first step of bringing the bottom of the case into close contact with a jig to form the bottom into a flat plate shape; a second step of joining a plate-like member to the lower surface of the case while the bottom of the case is in close contact with the jig. A method for manufacturing a battery pack comprising:

2. The second step includes a step of joining a cooling member or a protective member as the plate-like member to the bottom surface of the case. The method for manufacturing a battery pack according to claim 1 .

3. The first step includes a step of generating a magnetic force by energizing an electromagnet included in the jig, and attracting the bottom of the metal case to an attraction surface of the jig by the magnetic force generated by the electromagnet. The method for manufacturing a battery pack according to claim 2 .

4. The first step includes a step of drawing a vacuum from a vacuum circuit provided in the jig, and adsorbing the bottom of the case to an adsorption surface of the jig by the vacuum from the vacuum circuit. The method for manufacturing a battery pack according to claim 2 .

5. The second step is a step of joining the plate-like member to the lower surface of the case, and includes a step of adhering the plate-like member to the lower surface of the case via an adhesive.

5. The method for manufacturing a battery pack according to claim 3 or 4.

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