JP7709285B2 - Battery pack - Google Patents

Description

The present invention relates to a battery pack.

Battery packs mounted on electric vehicles and the like have a large capacity and generate a relatively large amount of heat during rapid charging, so it is preferable to provide a cooling structure. For example, Patent Document 1 discloses a technology in which a refrigerant flow path is formed between a storage section of a battery module constituting a battery pack and a plate member arranged at a distance from the storage section, and the battery module is cooled by the refrigerant flowing through the refrigerant flow path.

International Publication No. 2019/230325

In the technology disclosed in Patent Document 1, there is a risk that the plate member that is integrated with the battery module housing to form the refrigerant flow path may come into contact with other members on the side that does not face the refrigerant flow path. If the plate member comes into contact with other members, the refrigerant flowing through the refrigerant flow path will cool not only the battery module but also the other members. As a result, there is a risk that the cooling efficiency of the battery module in the battery pack will decrease.

The present invention was made in consideration of these problems, and aims to prevent a decrease in the cooling efficiency of the battery modules in the battery pack.

A battery pack according to an embodiment of the present invention includes a chargeable and dischargeable battery module and a storage section for storing the battery module. The storage section has a bottom on which the battery module is placed. The bottom includes a flow path section through which a coolant for cooling the battery module flows and a heat insulating section provided on the opposite side of the flow path section from the side on which the battery module is placed, and the flow path section and the heat insulating section are arranged so as to be adjacent to each other. The flow path section includes a first plate member that contacts the battery module and a second plate member that connects to an opposite surface of the first plate member that is opposite to the surface on which the battery module contacts. In the second plate member, both ends in the width direction are connected to the first plate member, and a central portion that is inside the both ends is separated from the opposite surface to form a flow path through which the coolant flows. The heat insulating section is arranged so as to be adjacent to the second plate member and to cover the entire central portion. The flow path is arranged so that the outer shape of the flow path in the width direction is contained inside the outer shape of the battery module in a plan view.

This invention makes it possible to prevent a decrease in the cooling efficiency of the battery pack.

FIG. 1 is a perspective view of a battery pack according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the battery pack. FIG. 3 is a plan view of the bottoms of the upper and lower storage sections as viewed from above. FIG. 4 is a cross-sectional view of the battery pack. FIG. 5 is an enlarged view of the vicinity of the opening in FIG.

The following describes an embodiment of the present invention with reference to the drawings.

Figure 1 is a perspective view of a battery pack 100 according to this embodiment. In the figure, the direction from the lower left to the upper right in the longitudinal direction of the battery pack 100 is indicated as the x-axis direction, the direction from the lower right to the upper left in the lateral direction is indicated as the y-axis direction, and the direction from bottom to top in the placement direction is indicated as the z-axis direction. In the following description, the up, down, left, and right directions in the figure are mainly used, but the placement direction of the battery pack 100 is not limited to the directions in the figure. In other words, the bottom of the battery pack 100 at the bottom of the figure is not necessarily placed on another component located vertically below, but may be placed so as to be in contact with an inverted surface, or may be placed under another component located vertically above.

Inside the battery pack 100, battery modules (not shown in FIG. 1) are arranged side by side in the direction of the mounting surface (xy plane), and the battery modules are arranged in one or more stages in the mounting direction (z axis). In detail, the lower stage (first stage) of battery modules are arranged side by side across the entire mounting surface, and the upper stage (second stage) of battery modules is arranged above the lower stage battery modules at the far right side of the figure in the longitudinal (x axis) direction. Hereinafter, the lower stage portion that accommodates the battery modules in a relatively large area is referred to as the lower stage accommodation section 1, and the upper stage portion that accommodates the battery modules in a relatively small area is referred to as the upper stage accommodation section 2. In the example of this embodiment, the battery modules are arranged in two stages, but this is not limited to this, and they may be arranged in three or more stages.

The lower storage section 1 and the upper storage section 2 each have a bottom (not shown in FIG. 1) on the lower side of the figure to which the battery module is fixed. These bottoms also have internal flow paths (not shown in FIG. 1), and the battery module is cooled by the refrigerant that flows through the flow paths.

The portion of the lower storage section 1 on the far right side of the figure where the upper storage section 2 is provided is tapered so that its width in the short side (y-axis) direction decreases toward the far right side of the figure. The portion on the front left side of the figure where the upper storage section 2 is not provided is configured with an equal width in the short side direction. In addition, the corners of the side surface of the lower storage section 1 on the front left side of the figure are chamfered, and a side surface is configured that intersects with both the long side surface and the short side surface. Note that this shape of the battery pack 100 is one example, and the shape of the battery pack 100 and the shape and number of battery modules stored therein can be designed as desired.

In FIG. 1, the configuration of the lower storage section 1 is shown to include a lower box section 3 that stores a battery module, and a lower cover 4 that is provided on the upper part of the lower box section 3.

The lower box section 3 is a box-shaped member with an open top, and the battery module is fixed to the bottom via a lower fixing plate (not shown in FIG. 1). A flow path through which the refrigerant flows inside is formed at the bottom of the lower box section 3. A lower refrigerant port 31 (lower refrigerant inlet ports 311, 312) is provided on the side surface on the front left side of the figure, which serves as an inlet for the refrigerant from the outside of the lower box section 3 to the flow path inside.

The lower cover 4 covers the portion of the upper opening of the lower box section 3 where the upper storage section 2 is not provided, i.e., the portion configured with an equal width in the short direction on the front left side of the figure. Therefore, the upper opening of the lower box section 3 is covered by the lower cover 4 on the front left side of the figure, and is covered by the upper storage section 2 on the rear right side of the figure.

In addition, FIG. 1 shows the configuration of the upper storage section 2, which includes an upper flow path member 5 on which the battery module is placed and which has a refrigerant flow path therein, and an upper box section 6 which stores the battery module.

The upper flow path member 5 is a plate-shaped member that fixes the battery module via an upper fixing plate (not shown in FIG. 1). In addition, two upper refrigerant ports 51 (upper refrigerant inlet 511, upper refrigerant outlet 512) that serve as flow path ports for the refrigerant between the external and internal flow paths of the upper flow path member 5 are provided on the side surface on the right front side of the figure.

The upper box section 6 is a box-shaped member with an open bottom. The upper box section 6 is fixed to the top surface of the upper flow path member 5 in a state in which it is positioned so as to cover the battery module placed on the upper flow path member 5. In this way, in the upper storage section 2 including the upper flow path member 5 and the upper box section 6, the battery module is placed on the upper flow path member 5, which is the bottom.

Details of the components of the lower storage section 1, including the lower box section 3 and the lower cover 4, and the components of the upper storage section 2, including the upper flow path member 5 and the upper box section 6, will be described with reference to FIG. 2.

Figure 2 is an exploded perspective view of the battery pack 100. Note that the long sides, short sides, and mounting direction in Figure 2 are the same as those in Figure 1. In the lower storage section 1, between the lower box section 3 and the lower cover 4, there is further shown a lower fixing plate 8 on which the battery module 7 is mounted on top. In the upper storage section 2, between the upper flow path member 5 and the upper box section 6, there is further shown an upper fixing plate 9 on which the battery module 7 is mounted on top. Each component will be described in detail below.

The lower box section 3 is configured in a box shape with an open top. The lower box section 3 is fixed on the mounting surface of another member different from the battery pack 100. In this example, the lower box section 3 is formed using metal materials such as aluminum and stainless steel by die casting (casting), press molding, etc. In addition, it may be formed using resin materials such as thermoplastic resin and FRP (fiber reinforced plastic) by injection molding, casting, etc. The bottom of the lower box section 3 is composed of two metal plates (not shown) spaced apart in the vertical direction, and a hollow section is formed between these two metal plates. Furthermore, a groove-shaped recess is provided on the upper surface of the upper one of the two metal plates, that is, on the upper surface of the bottom. This recess becomes the lower flow path 32 through which the refrigerant flows.

Furthermore, in the lower box section 3, lower refrigerant inlets 311, 312 are provided on the front left side of the figure as refrigerant ports that communicate between the lower flow path 32 and the outside of the lower box section 3, and a lower refrigerant outlet (not shown in FIG. 2) is provided on the side surface on the rear right side of the figure. The shape of the lower flow path 32 will be explained using FIG. 3(B) described later, and the detailed structure of the bottom of the lower box section 3 will be explained using the cross-sectional view of FIG. 4 described later.

The lower fixing plate 8 is a plate-shaped member and is made of a material with high thermal conductivity, for example, a metal material such as aluminum or stainless steel. The lower fixing plate 8 may be made of the same material as the lower box section 3, or may be made of a different material.

The lower fixing plate 8 is configured so that its outer periphery is approximately flush with the inner wall surface of the lower box section 3 in the inner direction of the placement surface (xy plane). As a result, the lower fixing plate 8 is fixed by the wall surface when placed on the upper surface of the bottom of the lower box section 3. The lower fixing plate 8 is in close contact with the upper surface of the bottom of the lower box section 3 where the lower flow path 32 is not provided. This prevents the refrigerant flowing through the lower flow path 32 from leaking out from between the lower box section 3 and the lower fixing plate 8.

The battery modules 7 are a common configuration in both the lower storage section 1 and the upper storage section 2, and are rectangular parallelepiped rechargeable secondary batteries. In this embodiment, a total of 12 battery modules are arranged in the lower storage section 1, two in the short direction and six in the long direction. In the upper storage section 2, a total of four battery modules are arranged, two in the short direction and two in the long direction. The size of the battery modules 7 varies depending on the short-side width of the lower box section 3 and upper box section 6 at the placement location.

In detail, of the 12 battery modules 7 provided in the lower storage section 1, the eight battery modules 7 provided in the equal-width section in the short direction on the front left side of the figure are larger than the four battery modules 7 provided in the tapered section on the back right side of the figure. Also, of the four battery modules 7 provided in the upper storage section 2, the two battery modules on the front left side of the figure are larger than the two battery modules on the back right side of the figure. This is because the upper box section 6 is configured in a tapered shape such that the width in the short direction becomes shorter in the longitudinal direction toward the back right side of the figure.

The battery modules 7 in the lower storage section 1 and the upper storage section 2 are electrically connected to each other. In particular, a plurality of battery modules 7 connected in series to achieve a desired voltage are connected in parallel to achieve a desired power capacity. As described above, the shape of the battery pack 100 in this embodiment is just one example, and the shape and number of the battery modules 7 stored therein can be designed as desired.

The lower cover 4 is a plate-shaped member, and is made of, for example, a metal material such as aluminum or stainless steel, or a resin material such as thermoplastic resin or FRP (fiber reinforced plastic). The lower cover 4 may be made of the same material as the lower box section 3, or a different material. The lower fixing plate 8 is configured so that the outer peripheral edge in the direction of the inner surface of the placement surface is approximately the same as the area of equal width in the short direction of the outer wall surface of the lower box section 3 where the upper storage section 2 is not provided on the front left side of the figure. The lower cover 4 is fixed on the side of the lower box section 3 using screws or the like. With this configuration, the lower cover 4 covers the part of the upper opening of the lower box section 3 where the upper storage section 2 is not provided.

In this way, in the lower storage section 1, the lower fixing plate 8 is placed on the upper surface of the bottom of the lower box section 3, and further, the battery module 7 is placed on the upper surface of the lower fixing plate 8. The space between the lower flow path 32 provided in the bottom of the lower box section 3 and the lower fixing plate 8 becomes the refrigerant flow path. Therefore, in the entire lower storage section 1, the bottom is formed by the lower box section 3 and the lower fixing plate 8, and the refrigerant flow path is formed inside the bottom.

The upper flow path member 5, like the lower box section 3, is formed in a plate shape from metal materials such as aluminum and stainless steel, or resin materials such as thermoplastic resin and FRP (fiber reinforced plastic). The outer wall surface of the upper flow path member 5 is configured so that the width in the short direction decreases toward the back right of the figure, and is approximately the same as the outer wall surface of the tapered part of the lower box section 3. In addition, like the bottom of the lower box section 3, the upper flow path member 5 is formed from two metal plates (not shown) spaced apart in the vertical direction, and a hollow portion is formed between these two metal plates. A groove-shaped recess is provided on the upper surface of the upper metal plate of the two metal plates, that is, the upper surface of the upper flow path member 5. The recess configured in this way becomes the upper flow path 52 through which the refrigerant flows.

Furthermore, as refrigerant ports that communicate between the upper flow path 52 and the outside of the upper flow path member 5 and serve as refrigerant outlets, upper-stage refrigerant ports 51 (upper-stage refrigerant inlet 511, upper-stage refrigerant outlet 512) are provided on the side surface on the front right side of the figure, and upper-stage refrigerant ports 51 (upper-stage refrigerant outlet 513, upper-stage refrigerant inlet 514) are provided on the side surface on the rear left side of the figure.

In addition, the upper flow path member 5 has two openings 53 that penetrate in the vertical (mounting) direction in a portion near the center in the mounting surface direction where the upper flow path 52 is not provided. A cable (not shown, also called a harness) passes through the openings 53, and the battery module 7 in the lower storage section 1 and the battery module 7 in the upper storage section 2 are electrically connected using the cable. The shape of the upper flow path 52 will be described later using FIG. 3(A), and the detailed configuration of the bottom of the upper flow path member 5 will be described later using the cross-sectional view of FIG. 4.

The upper fixing plate 9 is made of a material with high thermal conductivity, similar to the lower fixing plate 8. The upper fixing plate 9 is capable of covering the upper flow path 52, and is configured so that its outer periphery is inside the outer periphery of the upper flow path member 5.

The upper fixing plate 9 is in close contact with the upper surface of the upper flow path member 5 where the upper flow path 52 is not provided. This prevents the refrigerant flowing through the upper flow path 52 from leaking out from between the lower box portion 3 and the lower fixing plate 8. Furthermore, in the upper fixing plate 9, like the upper flow path member 5, an opening 91 is provided through which a cable connecting the battery module 7 in the lower storage portion 1 and the battery module 7 in the upper storage portion 2 passes.

When the battery pack 100 is assembled, the two openings 53 of the upper flow path member 5 communicate with the two openings 91 of the upper fixing plate 9. The battery module 7 in the lower storage section 1 and the battery module 7 in the upper storage section 2 are connected using cables passing through these openings 53, 91.

The upper box section 6 is composed of a box-shaped member with an open bottom and a flange section provided at the lower end of the box-shaped member. The opening of the box-shaped member is substantially larger than the upper fixing plate 9 in the direction of the mounting surface, and accommodates the upper fixing plate 9 on which the battery module 7 is mounted. Fastening holes (not shown) are provided at the end of the flange section. The upper box section 6 is fastened to the upper flow path member 5 at the flange section with screws or the like.

In this way, in the upper storage section 2, the upper fixing plate 9 is disposed on the upper surface of the upper flow path member 5, and further, the battery module 7 is placed on the upper surface of the upper fixing plate 9. The space between the upper flow path 52 provided in the upper flow path member 5 and the upper fixing plate 9 becomes the refrigerant flow path. Therefore, in the entire upper storage section 2, the bottom is formed by the upper flow path member 5 and the upper fixing plate 9, and the refrigerant flow path is formed inside the bottom.

Figure 3 is a plan view of the upper flow path member 5 and the lower box section 3 as viewed from above (the side opposite the mounting surface) in the mounting direction. In this figure, the left-right direction in the figure corresponds to the longitudinal direction (x-axis), the up-down direction in the figure corresponds to the lateral direction (y-axis), and the front-to-back direction on the paper corresponds to the mounting direction (z-axis). Note that the longitudinal and lateral directions in the following explanation are the same as those in Figures 1 and 2, and refer to directions based on the length and shortness of the entire battery pack 100 in the direction within the mounting surface.

Figure 3(A) shows the upper flow path member 5 with the upper flow path 52, and Figure 3(B) shows the lower box section 3 with the lower flow path 32.

As shown in FIG. 3A, the upper flow path 52 is composed of two upper flow paths 521, 522 that extend vertically in the figure and are provided from left to right in the figure. Note that the upper flow path 521 on the left side of the figure is configured so that the wall surface on the right side of the figure is recessed in order to form the opening 53.

The upper flow path 521 communicates with the upper refrigerant inlet 511 at the bottom of the figure, and communicates with the upper refrigerant outlet 513 at the top of the figure. The upper flow path 522 communicates with the upper refrigerant inlet 514 at the top of the figure, and communicates with the upper refrigerant outlet 512 at the bottom of the figure. At the top of the figure, the upper refrigerant outlet 513 and the upper refrigerant inlet 514 are connected by piping or the like (not shown).

As a result, the refrigerant flowing in from the upper refrigerant inlet 511 located on the lower left side of the figure flows from the bottom to the top in the upper flow path 521. The refrigerant discharged from the upper refrigerant outlet 513 located on the upper left side of the figure flows into the upper flow path 522 from the upper refrigerant inlet 514 located on the upper right side of the figure via piping, etc. Then, in the upper flow path 522, the refrigerant flows from the top to the bottom in the figure, and is then discharged from the upper refrigerant outlet 512 located on the lower right side of the figure.

The refrigerant flowing through the upper flow paths 521 and 522 in this manner cools the battery module 7 placed on the upper fixing plate 9 (not shown) on the front side of the page.

As shown in FIG. 3B, it is composed of lower flow paths 321 and 322 that extend in the left-right direction of the figure. Note that lower flow path 321 is provided on the upper side of the figure, and lower flow path 322 is provided on the lower side of the figure. Each of lower flow paths 321 and 322 is composed of multiple sub-flow paths (six in this figure) that are arranged side by side in the left-right direction of the figure.

The lower flow path 321 communicates with the lower refrigerant inlet 311 at the upper left of the figure, and communicates with the lower refrigerant outlet 313 at the upper right of the figure. The lower flow path 322 communicates with the lower refrigerant inlet 312 at the lower left of the figure, and communicates with the lower refrigerant outlet 314 at the lower right of the figure.

The six sub-flow paths of the lower flow paths 321, 322 are connected so that the refrigerant meanders in each of the lower flow paths 321, 322. This configuration prevents the refrigerant from stagnating in the lower flow paths 321, 322. The refrigerant flowing through the lower flow paths 321, 322 cools the battery module 7 placed on the lower fixing plate 8 (not shown) on the front side of the page.

The above-mentioned flow paths are merely examples, and the upper refrigerant port 51 (upper refrigerant inlet 511, upper refrigerant outlet 512, upper refrigerant outlet 513, upper refrigerant inlet 514) provided in the upper flow path member 5 and the lower refrigerant port 31 (lower refrigerant inlet 311, lower refrigerant inlet 312, lower refrigerant outlet 313, lower refrigerant outlet 314) provided in the lower box section 3 may be either an inlet or an outlet for the refrigerant. For example, the lower refrigerant outlet 314 and the upper refrigerant inlet 511 may be connected, the upper refrigerant outlet 513 and the upper refrigerant inlet 514 may be connected, and the upper refrigerant outlet 512 and the lower refrigerant outlet 313 may be connected. In such a case, the refrigerant flowing in from the lower refrigerant inlet 312 flows in the following order: lower refrigerant outlet 314, upper refrigerant inlet 511, upper refrigerant outlet 513, upper refrigerant inlet 514, upper refrigerant outlet 512, lower refrigerant outlet 313, and lower refrigerant inlet 311.

Figure 4 is a cross-sectional view of the battery pack 100. Figure 4(A) is a cross-sectional view taken along line I-I in Figure 1, Figure 4(B) is a cross-sectional view taken along line II-II, and Figure 4(C) is a cross-sectional view taken along line III-III. Note that in this figure, the left-right direction corresponds to the short side direction, the up-down direction corresponds to the placement direction, and the front-to-back direction corresponds to the long side direction.

Figure 4(A) is a cross-sectional view of a portion of the battery pack 100 where the battery modules 7 in the lower storage section 1 are stacked in one layer. Figure 4(B) is a cross-sectional view of a portion where the lower storage section 1 and the upper storage section 2 are stacked, and the battery modules 7 are stacked in two layers. Figure 4(C) is a cross-sectional view of a portion where the battery modules 7 are stacked in two layers, similar to Figure 4(B), at a position passing through the opening 53 of the upper flow path member 5 and the opening 91 of the upper fixing plate 9.

Figure 4 (A) shows a cross section of the lower storage section 1. The lower box section 3, which is open at the top on the upper side of the figure in the placement direction, is made by injection molding using aluminum or the like, and has hollow sides.

The bottom of the lower box section 3 at the bottom of the figure is configured with two plate members 33, 34 facing each other in the vertical direction of the figure with an air layer 35 between them. A lower flow path 32 that is recessed downward in the figure is provided on the upper surface of the plate member 33 at the top of the figure. The plate member 34 at the bottom of the figure is configured to have a recess similar to that of the plate member 33, so that the distance between the plate member 33 and the plate member 34 is constant.

Walls 36 are provided between the two plate members 33, 34 near both ends in the left-right direction of the figure, connecting the plate members 33, 34 in the up-down direction of the figure. Walls 37 are provided in the area in the center where the lower flow path 32 is not formed. The walls 36, 37 are provided in pairs in each area, have a predetermined length in the up-down direction of the figure, and extend in the front-to-back direction (longitudinal direction) in the figure.

The upper surface of the plate member 33 where the lower flow path 32 is not provided is fixed in close contact with the lower fixed plate 8. As a result, a flow path for the refrigerant 38 is formed between the lower flow path 32 of the plate member 33 and the lower fixed plate 8. Due to this configuration, the battery module 7 fixed to the upper part of the lower fixed plate 8 is cooled by the refrigerant 38 flowing between the lower flow path 32 and the lower fixed plate 8. In addition, an air layer 35 is provided at the lower part of the plate member 33, and since the air layer 35 has thermal insulation properties, the absorption of thermal energy into the refrigerant 38 flowing above the plate member 33 is suppressed. As a result, the refrigerant 38 can be suppressed from cooling objects other than the battery module 7, and the cooling efficiency of the battery module 7 can be improved.

Figure 4(B) shows a cross section of the part where the lower storage section 1 and the upper storage section 2 are stacked. Regarding the lower storage section 1, a description of the parts equivalent to the configuration shown in Figure 4(A) will be omitted. In addition, compared to Figure 4(A), the lower box section 3 of the lower storage section 1 is covered by the upper flow path member 5 of the upper storage section 2, not the lower cover 4.

The upper flow path member 5 is a plate-shaped member made of aluminum or the like by injection molding. The bottom of the upper flow path member 5 on the lower side of the figure is configured with two plate members 54, 55 facing each other with an air layer 56 between them, similar to the lower box section 3. The upper surface of the plate member 54 on the upper side of the figure is provided with an upper flow path 52 that is recessed downward in the figure. The plate member 55 on the lower side of the figure has a recess similar to that of the plate member 54, so that the distance between the plate member 55 and the plate member 54 is constant and an air layer 56 is provided between the plate members 54, 55.

Furthermore, similar to the walls 36, 37 of the lower box section 3 described above, walls 57, 58 are provided between the two plate members 54, 55 of the upper flow path member 5, connecting them. In detail, the walls 57 are provided near both ends in the left-right direction of the figure, and the walls 58 are provided in the area in the center where the upper flow path 52 is not formed. The walls 57, 58 are provided in pairs in each area, have a predetermined length in the up-down direction of the figure, and extend in the front-to-back direction (longitudinal direction) of the paper in the figure.

The upper surface of the plate member 54, where the lower flow path 32 is not provided, is fixed in close contact with the upper fixed plate 9. As a result, a flow path for the refrigerant 38 is formed between the upper flow path 52 of the plate member 54 and the upper fixed plate 9. Due to this configuration, the battery module 7 fixed to the upper part of the upper fixed plate 9 is cooled by the refrigerant 38 flowing between the upper flow path 52 and the upper fixed plate 9. In addition, an air layer 35 is provided at the lower part of the plate member 54, and since the air layer 35 has thermal insulation properties, the absorption of thermal energy into the refrigerant 38 flowing above the plate member 54 is suppressed. As a result, the refrigerant 38 can be suppressed from cooling objects other than the battery module 7, and the cooling efficiency of the battery module 7 can be improved.

Figure 4(C) shows a cross section at a different position from that in Figure 4(B) where the lower storage section 1 and upper storage section 2 are stacked. In this figure, explanations of parts of the lower storage section 1 and upper storage section 2 that are equivalent to the configurations shown in Figures 4(A) and (B) will be omitted.

Compared to the configuration shown in FIG. 4(B), the upper storage section 2 in this figure has openings 53, 91 near the center in the left-right direction of the figure that connect the inside of the lower box section 3 to the inside of the upper box section 6. The details of the configuration of these openings 53, 91 will be explained using FIG. 5.

Figure 5 is an enlarged view of the vicinity of the openings 53 and 91 provided in the upper box section 6.

As shown in this figure, of the plate members 54 and 55, the plate member 54 at the top of the figure has an end portion 54E formed by cutting away the center in the short side direction (left to right in the figure).

Furthermore, the plate member 55 on the lower side of the figure is broken near the center in the left-right direction of the figure, and the tip portion formed by the break is bent upward in the figure to form end portion 55E. Here, end portion 55E is configured so that the lateral surface in the left-right direction of the figure, i.e., the surface not facing opening 53, is separated a predetermined distance from end portion 54E of plate member 54. As described below, end portion 9E of upper fixing plate 9 is positioned in the space between ends 54E, 55E.

The upper fixing plate 9 is broken near the center in the left-right direction of the figure, and the tip formed by the break is bent downward in the figure to form the end 9E. The end 9E is positioned so that it is inserted between the end 54E of the plate member 54 and the end 55E of the plate member 55. The tip of the end 55E of the plate member 55 is welded to the surface of the end 9E of the upper fixing plate 9 that faces the opening 53.

With this configuration, the air layer 56 provided between the plate members 54, 55 is separated so as not to communicate with the interior of the lower box section 3 that houses the battery module 7 of the lower storage section 1, and the interior of the upper box section 6 that houses the battery module 7 of the upper storage section 2. The air layer 56 is kept at a relatively low temperature because it does not mix with the air inside the lower box section 3 and the upper box section 6 that is relatively hot due to the heat generated by the battery modules 7. As a result, the refrigerant 38 is inhibited from absorbing thermal energy from the plate member 54 side. This makes it possible to prevent the refrigerant 38 from cooling objects other than the battery modules 7, and improve the cooling efficiency of the battery modules 7.

In the above embodiment, the air layer 35 between the plate members 33 and 34 and the air layer 56 between the plate members 54 and 55 are used as heat insulating members, but this is not limited to the above. A heat insulating layer may be formed by filling the space between the plate members 33 and 34 with a gas such as nitrogen, drawing a vacuum, or filling the space with a foam material such as urethane.

According to this embodiment, the following effects can be obtained.

According to the battery pack 100 of this embodiment, the lower storage section 1 and upper storage section 2 that store the battery module 7 have bottoms (the bottom of the lower box section 3 and the lower fixing plate 8, and the upper flow path member 5 and the upper fixing plate 9) on which the battery module 7 is placed. The insides of these bottoms respectively have the lower flow path 32 and the upper flow path 52, and the air layers 35, 56 that have thermal insulation. The air layers 35, 56 are provided on the side of the lower flow path 32 and the upper flow path 52 opposite to the side on which the battery module 7 is placed.

With this configuration, the refrigerant 38 flowing through the lower flow path 32 and the upper flow path 52 at the bottom cools the battery module 7 fixed on the top surface of the bottom. At the same time, air layers 35, 56 with insulating properties are provided below the lower flow path 32 and the upper flow path 52 at the bottom, preventing the refrigerant 38 from absorbing thermal energy from the side opposite the side where the battery module 7 is provided. This prevents the refrigerant 38 from cooling objects other than the battery module 7, improving the cooling efficiency of the battery module 7.

According to the battery pack 100 of this embodiment, the lower storage section 1 (first storage section) and the upper storage section 2 (second storage section) are stacked via the bottom of the upper storage section 2 (upper flow path member 5 and upper fixing plate 9). The bottom is provided with openings 53, 91 that connect the inside of the lower storage section 1 to the inside of the upper storage section 2. Cables that connect the battery module 7 stored in the lower storage section 1 and the battery module 7 stored in the upper storage section 2 pass through the openings 53, 91. With this configuration, the integration density of the battery modules 7 can be improved, and the battery pack 100 can be made smaller.

According to the battery pack 100 of this embodiment, at the bottom of the upper storage section 2 (upper flow path member 5 and upper fixing plate 9), the air layer 35, which is a heat insulating section, and the openings 53 and 91 are separated from each other without communicating with each other by providing ends 9E and 55E.

With this configuration, the air layer 56 is kept at a relatively low temperature because it does not mix with the air inside the lower box section 3 and the upper box section 6, which becomes relatively hot due to heat generated by the battery modules 7. This prevents the refrigerant 38 from absorbing thermal energy from the side of the plate member 54 where the battery modules 7 are not provided. As a result, it is possible to prevent the refrigerant 38 from cooling objects other than the battery modules 7, and it is possible to improve the cooling efficiency of the battery modules 7.

The above-described embodiments of the present invention, the above-described embodiments, and the modified examples merely show some of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above-described embodiments.

REFERENCE SIGNS LIST 1 Lower storage section 2 Upper storage section 3 Lower box section 5 Upper flow path member 7 Battery module 8 Lower fixing plate 9 Upper fixing plate 35 Air layer 53, 91 Opening 100 Battery pack

Claims (4)

A battery pack including a chargeable and dischargeable battery module and a housing for housing the battery module,
the housing portion has a bottom portion on which the battery module is placed,
The bottom portion is
A flow path portion through which a refrigerant for cooling the battery module flows;
a heat insulating section provided on the opposite side of the flow path section from the side on which the battery module is placed,
The flow path portion and the heat insulating portion are disposed adjacent to each other ,
The flow path portion is
A first plate member in contact with the battery module;
a second plate-like member connected to an opposite surface of the first plate-like member opposite to a surface in contact with the battery module,
In the second plate-like member, both end portions in a width direction are connected to the first plate-like member, and a central portion that is inside the both end portions is separated from the opposite surface, thereby forming a flow path through which a refrigerant flows,
The heat insulating portion is disposed adjacent to the second plate-shaped member and so as to cover the entire central portion,
The flow path is a battery pack arranged such that the widthwise outline of the flow path is contained inside the widthwise outline of the battery module in a plan view . 2. The battery pack according to claim 1,
The storage section is configured with a first storage section and a second storage section, and is stacked in this order in the placement direction,
The battery module includes:
A first battery module accommodated in the first accommodation portion;
a second battery module accommodated in the second accommodation portion,
The bottom portion is
a first bottom portion on which the first battery module is placed;
and a second bottom portion on which the second battery module is placed. 3. The battery pack according to claim 2,
The second bottom portion is
A first region that accommodates the flow path portion and the heat insulating portion therein in a plan view;
A second region that is located outside the first region in a plan view,
A communication hole that communicates between the first storage portion and the second storage portion is formed in the second region,
A cable electrically connecting the first battery module and the second battery module is inserted into the communication hole of the battery pack. 4. The battery pack according to claim 3,
The heat insulating portion is configured as an air layer,
The air layer is separated so as not to communicate with the communication hole.