Battery pack and manufacturing method for battery pack

Abstract

To provide a battery pack having improved cooling performance and a manufacturing method for the battery pack.SOLUTION: There is provided a battery pack including a battery module, a battery case housing the battery module, and a cooler disposed on a bottom surface of the battery case. The bottom surface of the battery case has a central part having a shape in which a protrusion protruding to the cooler side extends in one direction, and a nonplanar part provided with a first side part and a second side part forming a ridge skirt of the protrusion. The cooler has at least two flow paths where coolant circulates, and a connection part connecting the two flow paths. At least one flow path is disposed on and opposite each of the first side part and the second side part. The connection part is disposed opposite the central part. There is also provided a manufacturing method for the battery pack.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, there are known battery packs to be mounted on vehicles, etc. For example, there is known a battery pack that includes a case that houses a battery stack, a cooler provided outside the case, an outer thermally conductive layer disposed between the case and the cooler, and an inner thermally conductive layer disposed between the battery stack and the case (Patent Document 1). [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] In a battery pack, increasing the battery capacity also increases the amount of heat generated by the battery, which requires improving the cooling performance. A battery pack using multiple thermally conductive layers is known as a battery pack with improved cooling performance (Patent Document 1), but further improvements in cooling performance have been desired.

[0005] An object of one embodiment of the present disclosure is to provide a battery pack with improved cooling performance and a method for manufacturing the battery pack. [Means for solving the problem]

[0006] The means for solving the problems include the following aspects. <1> A battery pack comprising: a battery module; a battery case that houses the battery module; and a cooler that is arranged on the bottom surface of the battery case, wherein the bottom surface of the battery case has a non-flat portion that includes a central portion having a shape in which a convex portion that is convex toward the cooler side extends in one direction, and a first side portion and a second side portion that form the base of the convex portion, and wherein the cooler has at least two flow paths through which a refrigerant flows and a connecting portion that connects the two flow paths, at least one flow path being arranged opposite each of the first side portion and the second side portion, and the connecting portion being arranged opposite the central portion. <2> The first side portion and the second side portion are each inclined toward the center portion, and the flow passages are disposed at an incline corresponding to the first side portion and the second side portion. <1> The battery pack according to claim 1. <3> The heat transfer device includes an outer heat conductive material, and the flow passages are disposed opposite the first side portion and the second side portion via the outer heat conductive material having a substantially uniform thickness. <1> or <2> The battery pack according to claim 1. <4> A method for manufacturing a battery pack in which a cooler having a flow passage and a connection portion is placed on the bottom surface of a battery case that houses a battery module, the bottom surface having a non-flat portion with a convex portion that is convex toward the cooler, the connection portion being deformable, and the method includes a step of assembling the cooler to the bottom surface while following the shape of the non-flat portion by placing the connection portion opposite the convex portion. <5> The step of assembling the cooler to the bottom surface is performed by a jig for assembling the cooler, the jig having a pressing roller, and the jig presses the cooler to the bottom surface using the pressing roller, thereby assembling the cooler to the bottom surface. <4> A method for manufacturing the battery pack according to claim 1. [Effects of the Invention]

[0007] According to one embodiment of the present disclosure, a battery pack with improved cooling performance and a method for manufacturing the battery pack are provided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a battery pack. [Figure 2]FIG. 2 is a schematic plan view showing an example of a cooler. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. [Figure 4] FIG. 4 is a schematic cross-sectional view of a battery pack in which the thickness of the outer thermally conductive material is non-uniform. [Figure 5] FIG. 5 is a schematic plan view of a cooler having a flat shape. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. When embodiments of the present disclosure are described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Components indicated by the same reference numerals in the drawings are the same components. In some drawings, only some components may be designated by reference numerals. The dimensional ratios in the drawings do not necessarily represent the actual dimensional ratios. In the present disclosure, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.

[0010] <Battery pack> The battery pack of the present disclosure includes a battery module, a battery case that houses the battery module, and a cooler that is disposed on the bottom surface of the battery case. The bottom surface of the battery case has a non-planar portion including a central portion and first and second side portions. The central portion has a shape in which a convex portion that is convex toward the cooler extends in one direction, and the first and second side portions each form a foot of the convex portion. The cooler has at least two flow passages through which a refrigerant flows and a connecting portion connecting the two flow passages, at least one flow passage being disposed opposite each of the first and second side portions, and the connecting portion being disposed opposite the center portion.

[0011] With the battery pack of the present disclosure having the above configuration, even if the bottom surface of the battery case has a non-flat portion, the cooler can be installed by adjusting the gap between the components that make up the battery pack so that it follows the shape of the non-flat portion. Therefore, the cooling performance of the battery module by the cooler is not impaired, and the cooling performance of the battery pack as a whole is improved.

[0012] As shown in FIG. 1, in one example of a battery pack according to the present disclosure, a battery pack 10 includes a battery module 11. The battery module 11 includes a plurality of battery stacks therein. Each battery stack includes a plurality of power storage cells. Examples of the power storage cells include lithium ion batteries. The plurality of battery stacks are arranged side by side within the battery module 11. The battery module 11 may include a single battery stack therein.

[0013] Although not shown in FIG. 1, the battery module 11 is housed in a battery case. The battery case includes a lower case 12 and an upper case (not shown), and the case structure is formed by combining the lower case 12 and the upper case. The lower case 12 is disposed below the battery module 11 and forms the bottom surface of the battery case. The lower case 12 may be disposed below the battery module 11 with the inner heat conductive material 13 interposed therebetween.

[0014] The lower case 12 has a non-flat portion including a central portion 12a and first and second side portions 12b and 12c. The central portion 12a has a shape in which a convex portion that is convex toward the cooler 14 extends in one direction. The one direction refers to the y direction (see FIG. 2), which is the longitudinal direction of the flow passage 14a of the cooler 14. The first side portion 12b and the second side portion 12c each form the foot of the convex portion of the central portion 12a. The first side portion 12b and the second side portion 12c are formed continuously in the y direction on both sides of the convex portion in the x direction, which is perpendicular to the y direction in which the convex portion extends. Because they are formed continuously with the convex portion, the first side portion 12b and the second side portion 12c also have a shape that extends in the y direction, similar to the convex portion. As described above, the bottom surface of the lower case 12 has a non-flat portion that includes a convex portion and a base of the convex portion.

[0015] The cooler 14 is disposed on the bottom surface of the lower case 12 and cools the battery module 11 through the lower case 12. The cooler 14 is made of a metal such as aluminum.

[0016] 2, the cooler 14 has flow passages 14b and 14c and a connecting portion 14a connecting these flow passages. Each of the flow passages 14b and 14c has a flow path through which a refrigerant such as water flows. The cooler 14 may have a plurality of combinations of the flow passages 14b, the connecting portion 14a, and the flow passages 14c, or may have only one combination. The flow passages 14a and 14b are connected to an inlet pipe 21 and an outlet pipe 22 that supply a refrigerant to the flow passages 14a and 14b. The refrigerant flows into the inlet pipe 21 and flows out from the outlet pipe 22. The cooler 14 continuously exhibits its cooling performance by circulating the refrigerant.

[0017] The connecting portion 14a connects the flow passage 14a and the flow passage 14b. The connecting portion 14a is deformable. The connecting portion 14a is only required to be configured to be deformable, and the deformation may be physical deformation or material deformation. Examples of physical deformation include a spring shape, a bellows shape, etc. Examples of material deformation include using an elastically deformable material. A combination of physical deformation and material deformation may also be used. For example, the connecting portion 14a may be configured by using an elastically deformable metal and forming this metal into a bellows shape.

[0018] As shown in Fig. 3, the deformable connecting portion 14a can be formed in a bellows shape by repeatedly folding the metal that constitutes the connecting portion 14a into a mountain fold and a valley fold. Because the connecting portion 14a has a bellows shape, by arranging the connecting portion 14a opposite a protrusion on the bottom surface of the lower case 12, the connecting portion 14a deforms in accordance with the protrusion, and the flow passages 14b and 14c connected to the connecting portion 14a can also move, for example, in the direction of the arrows in Fig. 3, and can be arranged to correspond to the bottom surface of the lower case 12. This allows the gaps between the components of the battery pack 10 to be adjusted.

[0019] Flow path 14b is disposed opposite first side portion 12b, and flow path 14c is disposed opposite second side portion 12c. Flow path 14b and flow path 14c may be disposed in first side portion 12b and second side portion 12c, respectively, via outer thermal conductive material 15. The connecting portion 14a is disposed opposite the central portion 12a of the lower case 12.

[0020] The bottom surface of the lower case 12 has a central portion 12a that has a convex portion that is convex toward the cooler 14 side and a non-flat portion that has a base of the convex portion, so that when the flow path 14b is arranged opposite the first side portion 12b, the connection portion 14a is arranged opposite the central portion 12a, and the flow path 14c is arranged opposite the second side portion 12c, the flow paths 14b and 14c of the cooler 14 and the connection portion 14a are also arranged non-planarly in correspondence with the non-flat portion of the bottom surface of the lower case 12. In this way, the flow paths 14b and 14c and the connection portion 14a are arranged along the shape of the non-flat portion of the bottom surface of the lower case 12.

[0021] To improve the thermal performance of the battery module 11, it is conceivable to form the bottom surface of the lower case 12 in a convex shape that is convex toward the cooler 14. Then, to improve the cooling performance of the cooler 14, it is conceivable to control the gaps between the various components that make up the battery pack 10, such as the battery module 11, lower case 12, and cooler 14. 4, in battery pack 110, in order to control the gap between lower case 112 and cooler 114, outer thermally conductive material 115 interposed between cooler 114 and lower case 112 is formed to have an uneven thickness corresponding to the convex bottom surface of lower case 112, and is brought into close contact with cooler 114, which is formed flat, and the bottom surface of lower case 112, which has a non-flat portion, is brought into close contact with cooler 114. In this case, cooler 114 has a flat shape as a whole, including connection portion 114a and flow paths 114b and 114c, as shown in FIG. 5, and it is difficult to make cooler 114 conform to the shape of a battery case with a non-flat bottom surface.

[0022] The inventors focused on the shape of the cooler 14 to further improve cooling performance. The cooler 14 is composed of flow paths 14b, 14c, and a connecting portion 14a, and by deforming the connecting portion 14a, the shape of the cooler 14 can be adjusted to follow the shape of the battery case. Furthermore, by arranging the cooler 14 to correspond to the non-flat portion of the bottom surface of the lower case 12 of the battery case, cooling performance can be further improved compared to when the shape of the outer thermally conductive material 15 is formed to be non-uniform (see FIG. 4). It is presumed that the improved cooling performance of the battery pack of the present disclosure is due to the controlled gap between the cooler 14 and the lower case 12 as described above.

[0023] In the battery pack 10, it is preferable that the first side portion 12b and the second side portion 12c are each inclined toward the central portion 12a, and the flow passages are arranged at an incline corresponding to the first side portion 12b and the second side portion 12c, respectively (see FIG. 1).

[0024] On the bottom surface of the lower case 12, the first side portion 12b and the second side portion 12c are each shaped to slope toward the center portion 12a, and the cooler 14 is attached in a shape that corresponds to the bottom surface of the lower case 12. This causes a force to act in the direction that the lower case 12 presses the battery module 11, creating areas where the battery module 11 and the lower case 12 are in closer contact with each other. This allows for smooth heat transfer and more effective cooling of the battery module 11 via the lower case 12. An inner heat conductive material 13 may be interposed between the battery module and the lower case 12, which is also preferable because it improves the cooling performance.

[0025] The battery pack 10 includes an outer thermally conductive material 15. The flow paths 14b and 14c are preferably disposed opposite the first side portion 12b and the second side portion 12c, respectively, via the outer thermally conductive material 15, which has a substantially uniform thickness.

[0026] Since the flow paths 14b and 14c are arranged opposite the first side portion 12b and the second side portion 12c, respectively, the thickness of the outer heat conductive material 15 can be made substantially uniform. "Substantially uniform" means that the thickness is uniform at a glance, and the variation in thickness is approximately 10% or less. This allows contact between flow path 14b, outer thermal conductive material 15, and first side portion 12b, or between flow path 14c, outer thermal conductive material 15, and second side portion 12c, via outer thermal conductive material 15 of a substantially uniform thickness, thereby facilitating smooth heat transfer therebetween. This allows for more efficient cooling of battery module 11 via lower case 12 by flow paths 14b and 14c.

[0027] Furthermore, when the inner thermal conductive material 13 is disposed between the lower case 12 and the battery module 11, it is preferable to adjust the thickness of the inner thermal conductive material 13. This adjusts the gaps between all of the components of the flow paths 14b and 14c, the optionally disposed outer thermal conductive material 15, the lower case 12, the optionally disposed inner thermal conductive material 13, and the battery module 11. This allows for smoother heat transfer, further improving cooling performance. In addition, the contact area, contact strength, and other adhesion between the components can be adjusted, further improving cooling performance.

[0028] <Battery pack manufacturing method> The manufacturing method of the battery pack disclosed herein is a manufacturing method of a battery pack in which a cooler having a flow passage and a connection portion is disposed on the bottom surface of a battery case that houses battery modules, and includes a step of assembling the cooler to the bottom surface while conforming to the shape of the non-flat portion by arranging the connection portion opposite a convex portion, wherein the bottom surface includes a non-flat portion having a convex portion that is convex toward the cooler, and the connection portion is deformable.

[0029] The manufacturing method of the battery pack 10 includes a step of assembling the cooler 14 to the bottom surface while allowing it to follow the shape of the non-flat portion of the bottom surface of the lower case 12 by positioning the deformable connecting portion 14a opposite the convex portion of the bottom surface of the lower case 12. As a result, the connecting portion 14a deforms to correspond to the convex portion on the bottom surface of the lower case 12, and the entire cooler 14 including the connecting portion 14a and the flow portion is assembled to the bottom surface while following the shape of the non-flat portion on the bottom surface of the lower case 12, allowing the cooler 14 to be installed by adjusting the gap between the cooler 14 and the lower case 12. Therefore, the cooling performance of the cooler 14 for the battery module 11 is not impaired, and the cooling performance of the battery pack 10 as a whole is improved.

[0030] The process of assembling the cooler 14 to the bottom surface is preferably carried out using a jig for assembling the cooler 14, the jig being equipped with a pressing roller, and the jig preferably assembles the cooler 14 to the bottom surface by pressing the cooler 14 against the bottom surface using the pressing roller.

[0031] By providing a shape-following mechanism, such as a pressure roller, on the side of the jig used to assemble the cooler 14, which applies pressure to make the shape of the cooler 14 follow the shape of the bottom surface of the lower case 12, it becomes possible to adjust the gap between the cooler 14 and the lower case 12 with greater precision, thereby further improving the cooling performance. [Explanation of symbols]

[0032] 10, 110 battery pack 11 Battery module 12, 112 Lower case 12 Distribution path 12a central part 12b First side 12c Second side 13 Inner thermal conductive material 14, 114 Cooler 14a, 114a connection 14a, 114b Distribution path 14b, 114c Distribution path 14c Distribution path 15, 115 Outer thermal conductive material 21 Inlet piping 22 Outlet piping

Claims

1. a battery module, a battery case that houses the battery module, and a cooler that is disposed on a bottom surface of the battery case; the bottom surface of the battery case has a non-flat portion including a central portion having a shape in which a convex portion that is convex toward the cooler side extends in one direction, and a first side portion and a second side portion that form a foot of the convex portion, the cooler has at least two flow passages through which a refrigerant flows and a connection portion that connects the two flow passages; At least one of the flow passages is disposed opposite each of the first side portion and the second side portion, The connection portion is disposed opposite the central portion of the battery pack.

2. the first side portion and the second side portion are each inclined toward the central portion; The battery pack according to claim 1 , wherein the flow passage is disposed at an incline corresponding to each of the first side portion and the second side portion.

3. an outer thermally conductive material; The battery pack according to claim 1 , wherein the flow passages are disposed opposite the first side portion and the second side portion, with the outer thermally conductive material having a substantially uniform thickness interposed therebetween.

4. A method for manufacturing a battery pack in which a cooler having a flow path and a connection portion is disposed on a bottom surface of a battery case that houses battery modules, the bottom surface includes a non-flat portion having a convex portion that is convex toward the cooler, the connecting portion is deformable; a step of assembling the cooler to the bottom surface while conforming to the shape of the non-flat portion by arranging the connecting portion opposite the convex portion.

5. the step of assembling the cooler to the bottom surface is performed using a jig for assembling the cooler; The jig includes a pressing roller, The method for manufacturing a battery pack according to claim 4 , wherein the jig assembles the cooler to the bottom surface by pressing the cooler against the bottom surface using the pressing roller.

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