Battery pack

Abstract

To prevent reduction in cooling efficiency of a battery module inside a battery pack.SOLUTION: A battery pack has: a chargeable / dischargeable battery module; and a housing part which houses the battery module. The housing part has a bottom part on which the battery module is placed. The bottom part has: a passage part through which a coolant for cooling the battery module flows; and a heat insulating part provided on the opposite side, across the passage part, to the side where the battery module is placed.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a battery pack.

Background Art

[0002] A battery pack mounted on an electric vehicle or the like has a large capacity and a relatively large amount of heat generation during rapid charging or the like, so it is preferable to be provided with a cooling structure. For example, Patent Document 1 discloses a technique in which a refrigerant flow path is formed between a housing portion of a battery module constituting a battery pack and a plate member disposed apart from the housing portion, and the battery module is cooled by a refrigerant flowing through the refrigerant flow path.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique disclosed in Patent Document 1, a plate member that forms a refrigerant flow path integrally with the housing portion of the battery module may come into contact with other members on the surface on the side not facing the refrigerant flow path. If the plate member comes into contact with other members, the refrigerant flowing through the refrigerant flow path cools not only the battery module but also other members. As a result, there is a risk of a decrease in the cooling efficiency of the battery module in the battery pack.

[0005] The present invention has been made in view of such problems, and an object thereof is to suppress a decrease in the cooling efficiency of the battery module in the battery pack.

Means for Solving the Problems

[0006] A battery pack according to an embodiment of the present invention includes a rechargeable battery module and a housing portion that houses the battery module. The housing portion has a bottom portion on which the battery module is placed. The bottom portion includes a flow path portion through which a refrigerant for cooling the battery module flows, and a heat insulating portion provided on a side opposite to the side on which the battery module is placed with respect to the flow path portion, and the flow path portion and the heat insulating portion are arranged adjacent to each other. The flow path section includes a first plate-like member that contacts the battery module, and a second plate-like member that is connected to the opposite surface of the first plate-like member, which is opposite to the surface that contacts the battery module. In the second plate-like member, both end portions in the width direction are connected to the first plate-like member, and a flow path through which the refrigerant flows is formed by the central portion, which is inside both end portions, being separated from the opposite surface. The heat insulation section is disposed adjacent to the second plate-like member and covers the entire central portion. The flow path is arranged such that, in plan view, the outer shape in the width direction of the flow path fits inside the outer shape in the width direction of the battery module.

Advantages of the Invention

[0007] According to the present invention, it is possible to suppress a decrease in the cooling efficiency of the battery pack.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like.

[0010] FIG. 1 is a perspective view of the battery pack 100 of the present embodiment. In the figure, the direction from the lower left to the upper right in the longitudinal direction of the battery pack 100 is the x-axis direction, the direction from the lower right to the upper left in the short-side direction is the y-axis direction, and the direction from the bottom to the top in the mounting direction is the z-axis direction. In the following description, the up, down, left, and right directions in the figure are mainly used, but the mounting direction of the battery pack 100 is not limited to the direction in the figure. That is, the bottom at the lower part of the battery pack 100 in the figure is not necessarily mounted on another member vertically below, but may be mounted in contact with the inverted surface, or may be mounted under another member vertically above.

[0011] Inside the battery pack 100, battery modules (not shown in FIG. 1) are arranged side by side in the mounting plane (xy plane) direction, and the battery modules are configured in one or two or more stages in the mounting direction (z-axis). Specifically, the lower-stage (first-stage) battery modules are arranged side by side over the entire mounting surface, and in the right-back side in the longitudinal (x-axis) direction, the upper-stage (second-stage) battery module is arranged above the lower-stage battery module. Hereinafter, the portion that accommodates the battery module with a relatively large area in the lower stage is referred to as the lower accommodation portion 1, and the portion that accommodates the battery module with a relatively small area in the upper stage is referred to as the upper accommodation portion 2. In the example of the present embodiment, the battery module is configured in two stages, but it is not limited thereto and may be configured in three or more stages.

[0012] The lower accommodation portion 1 and the upper accommodation portion 2 have bottoms (not shown in FIG. 1) that fix the battery modules on the lower side of the figure. And those bottoms are provided with flow paths (not shown in FIG. 1) inside, and the battery modules are cooled by the refrigerant flowing through the flow paths.

[0013] In the lower accommodation portion 1, the portion where the upper accommodation portion 2 on the upper right rear side in the figure is provided is configured in a tapered shape such that the width in the short side (y-axis) direction becomes shorter toward the upper right rear side in the figure. The portion where the upper accommodation portion 2 on the upper left front side in the figure is not provided is configured to have a constant width in the short side direction. Further, in the lower accommodation portion 1, the corner portion is chamfered on the side surface on the upper left front side in the figure, and a side surface that intersects both the longitudinal side surface and the short side surface is configured. Note that such a shape of the battery pack 100 is an example, and the shape of the battery pack 100, the shape and number of battery modules accommodated therein, etc. can be arbitrarily designed.

[0014] In FIG. 1, as a configuration related to the lower accommodation portion 1, a lower box portion 3 that accommodates a battery module and a lower cover 4 provided above the lower box portion 3 are shown.

[0015] The lower box portion 3 is a box-shaped member with an open upper portion, and a battery module is fixed to the bottom via a lower fixing plate (not shown in FIG. 1). Further, a flow path through which a refrigerant flows is formed in the bottom of the lower box portion 3. On the side surface on the upper left front side in the figure, a lower refrigerant port 31 (lower refrigerant inlets 311 and 312) serving as an inlet for the refrigerant from the outside of the lower box portion 3 to the internal flow path is provided.

[0016] The lower cover 4 covers the portion of the upper opening of the lower box portion 3 where the upper accommodation portion 2 is not provided, that is, the portion configured to have a constant width in the short side direction on the upper left front side in the figure. Therefore, the upper opening of the lower box portion 3 is covered by the lower cover 4 on the upper left front side in the figure and is covered by the upper accommodation portion 2 on the upper right rear side in the figure.

[0017] Also, in FIG. 1, as a configuration related to the upper accommodation portion 2, an upper flow path member 5 that places a battery module and has a refrigerant flow path therein, and an upper box portion 6 that accommodates the battery module are shown.

[0018] 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). Further, on the side surface at the front right side of the figure, two upper refrigerant ports 51 (upper refrigerant inlet 511 and upper refrigerant outlet 512) serving as refrigerant flow ports between the outside and the inside flow paths of the upper flow path member 5 are provided.

[0019] The upper box portion 6 is a box-shaped member with an open bottom. The upper box portion 6 is fixed to the upper surface of the upper flow path member 5 in a state of being arranged so as to cover the battery module placed on the upper flow path member 5. Thus, in the upper housing portion 2 including the upper flow path member 5 and the upper box portion 6, the battery module is placed on the upper flow path member 5 which is the bottom.

[0020] Details of the constituent members of the lower housing portion 1 including the lower box portion 3 and the lower cover 4, and details of the constituent members of the upper housing portion 2 including the upper flow path member 5 and the upper box portion 6 will be described with reference to FIG. 2.

[0021] FIG. 2 is an exploded perspective view of the battery pack 100. Note that the longitudinal, lateral, and placement directions in FIG. 2 are the same as those in FIG. 1 respectively. In the lower housing portion 1, a lower fixing plate 8 for placing the battery module 7 on the upper part is further shown between the lower box portion 3 and the lower cover 4. In the upper housing portion 2, an upper fixing plate 9 for placing the battery module 7 on the upper part is further shown between the upper flow path member 5 and the upper box portion 6. Hereinafter, details of each constituent member will be described.

[0022] The lower box portion 3 is configured in a box shape with an open top. Also, the lower box portion 3 is fixed on the placement surface of other members different from the battery pack 100. In this example, the lower box portion 3 is formed using a metal material such as aluminum or stainless steel by die casting (casting), press molding, etc. Alternatively, it may be formed using a resin material such as a thermoplastic resin or FRP (fiber-reinforced plastic) by injection molding, casting, etc. The bottom of the lower box portion 3 is composed of two metal plates (not shown) spaced apart in the vertical direction, and a hollow portion is formed between these two metal plates. Further, a groove-shaped recess is provided on the upper surface of the upper metal plate among the two metal plates, that is, on the upper surface of the bottom. This recess serves as the lower flow path 32 through which the refrigerant flows.

[0023] Furthermore, in the lower box portion 3, on the front left side in the figure, lower refrigerant inlets 311 and 312 are provided as refrigerant ports that communicate between the lower flow path 32 and the outside of the lower box portion 3, and on the side surface at the rear right side in the figure, a lower refrigerant outlet (not shown in FIG. 2) is provided. Note that the shape of the lower flow path 32 will be described using FIG. 3(B) to be described later, and the detailed configuration of the bottom of the lower box portion 3 will be described using the cross-sectional view of FIG. 4 to be described later.

[0024] The lower fixing plate 8 is a plate-shaped member and is composed 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 composed of the same material as the lower box portion 3 or a different material.

[0025] The lower fixing plate 8 is configured such that its outer peripheral edge is substantially the same as the inner wall surface of the lower box portion 3 in the in-plane direction of the placement surface (xy plane). Thereby, the lower fixing plate 8 is fixed by the wall surface when disposed on the upper surface of the bottom of the lower box portion 3. Note that the lower fixing plate 8 is in close contact with the upper surface of the bottom of the lower box portion 3 where the lower flow path 32 is not provided. Therefore, it is possible to prevent the refrigerant flowing through the lower flow path 32 from leaking between the lower box portion 3 and the lower fixing plate 8.

[0026] The battery module 7 has a common configuration in both the lower accommodation part 1 and the upper accommodation part 2, and is a rectangular parallelepiped rechargeable secondary battery. In the present embodiment, in the lower accommodation part 1, a total of 12 are arranged, 2 in the short side direction and 6 in the long side direction. Also, in the upper accommodation part 2, a total of 4 are arranged, 2 in the short side direction and 2 in the long side direction. The size of the battery module 7 varies according to the width in the short side direction of the lower box part 3 and the upper box part 6 at the placement location.

[0027] Specifically, among the 12 battery modules 7 provided in the lower accommodation part 1, the 8 battery modules 7 provided in the equal-width part in the short side direction on the left front side in the figure are larger than the 4 battery modules 7 provided in the tapered part on the right rear side in the figure. Also, among the 4 battery modules 7 provided in the upper accommodation part 2, the 2 battery modules on the left front side in the figure are larger than the 2 battery modules on the right rear side in the figure. This is because the upper box part 6 is configured in a tapered shape such that the width in the short side direction becomes shorter toward the right rear in the long side direction.

[0028] Note that the battery modules 7 in the lower accommodation part 1 and the upper accommodation part 2 are electrically connected to each other. Specifically, a plurality of battery modules 7 connected in series so as to obtain a desired voltage are connected in parallel so as to obtain a desired power capacity. As described above, the shape of the battery pack 100 in the present embodiment is an example, and the shape, number, etc. of the battery modules 7 accommodated inside can be arbitrarily designed.

[0029] The lower cover 4 is a plate-shaped member, which is made of, for example, a metal material such as aluminum or stainless steel, or a resin material such as a thermoplastic resin or FRP (fiber-reinforced plastic). The lower cover 4 may be made of the same material as the lower box portion 3 or a different material. The lower fixing plate 8 is configured such that the outer peripheral edge in the direction of the mounting surface is substantially the same as the region having the same width in the short-side direction of the outer wall surface of the lower box portion 3 where the upper storage portion 2 on the front left side in the figure is not provided. Then, the lower cover 4 is fixed on the side surface of the lower box portion 3 using screws or the like. With such a configuration, the lower cover 4 covers the portion of the upper opening of the lower box portion 3 where the upper storage portion 2 is not provided.

[0030] As described above, in the lower storage portion 1, the lower fixing plate 8 is disposed on the upper surface of the bottom of the lower box portion 3, and further, the battery module 7 is placed on the upper surface of the lower fixing plate 8. Then, the space between the lower flow path 32 provided at the bottom of the lower box portion 3 and the lower fixing plate 8 serves as a refrigerant flow path. Therefore, in the entire lower storage portion 1, the bottom is constituted by the lower box portion 3 and the lower fixing plate 8, and a refrigerant flow path is formed inside the bottom.

[0031] Similar to the lower box portion 3, the upper flow path member 5 is formed in a plate shape using, for example, a metal material such as aluminum or stainless steel, or a resin material such as a thermoplastic resin or FRP (fiber-reinforced plastic). The outer wall surface of the upper flow path member 5 is configured such that the width in the short-side direction becomes shorter toward the back right direction in the figure, and is substantially the same as the outer wall surface of the tapered portion in the lower box portion 3. Also, similar to the bottom of the lower box portion 3, the upper flow path member 5 is constituted by 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 among the two metal plates, that is, on the upper surface of the upper flow path member 5. The recess configured in this way serves as the upper flow path 52 through which the refrigerant flows.

[0032] Furthermore, as a refrigerant port that communicates between the upper flow path 52 and the outside of the upper flow path member 5 and serves as a refrigerant outlet, an upper refrigerant port 51 (upper refrigerant inlet 511, upper refrigerant outlet 512) is provided on the side surface at the front right of the figure, and an upper refrigerant port 51 (upper refrigerant outlet 513, upper refrigerant inlet 514) is provided on the side surface at the back left of the figure.

[0033] In addition, in the upper flow path member 5, two openings 53 that penetrate in the vertical (mounting) direction are provided at a portion near the center in the direction of the mounting surface where the upper flow path 52 is not provided. A cable (not shown, also referred to as a harness) passes through the opening 53, and the battery module 7 in the lower housing portion 1 and the battery module 7 in the upper housing portion 2 are electrically connected using the cable. Note that the shape of the upper flow path 52 will be described with reference to FIG. 3(A) described later, and the detailed configuration of the bottom of the upper flow path member 5 will be described with reference to the cross-sectional view of FIG. 4 described later.

[0034] 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 can cover the upper flow path 52, and its outer peripheral edge is configured to be inside the outer periphery of the upper flow path member 5.

[0035] 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. Therefore, leakage of the refrigerant flowing through the upper flow path 52 from between the lower box portion 3 and the lower fixing plate 8 is prevented. Furthermore, in the upper fixing plate 9, similar to the upper flow path member 5, an opening 91 through which a cable connecting the battery module 7 in the lower housing portion 1 and the battery module 7 in the upper housing portion 2 passes is provided.

[0036] In a state where 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. Then, the battery module 7 in the lower housing portion 1 and the battery module 7 in the upper housing portion 2 are connected using the cable passing through these openings 53 and 91.

[0037] The upper box portion 6 is composed of a box-shaped member with an open lower part and a flange portion 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 placement surface, and houses the upper fixing plate 9 on which the battery module 7 is placed inside. A fastening hole (not shown) is provided at the end of the flange portion. The upper box portion 6 is fastened to the upper flow path member 5 by screws or the like at the flange portion.

[0038] In this way, in the upper housing portion 2, the upper fixing plate 9 is arranged 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. And 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 whole of the upper housing portion 2, the bottom is composed of the upper flow path member 5 and the upper fixing plate 9, and a refrigerant flow path is configured inside the bottom.

[0039] FIG. 3 is a plan view of the upper flow path member 5 and the lower box portion 3 as viewed from above (the side opposite to the placement surface) in the placement direction. In this figure, the left-right direction of the figure corresponds to the longitudinal direction (x-axis), the up-down direction of the figure corresponds to the short-side direction (y-axis), and the front-back direction of the paper corresponds to the placement direction (z-axis). In addition, the longitudinal and short-side directions in the following description are the same as those in the description of FIGS. 1 and 2, and indicate the directions based on the length and shortness in the direction of the entire placement surface of the battery pack 100.

[0040] FIG. 3(A) shows the upper flow path member 5 provided with the upper flow path 52, and FIG. 3(B) shows the lower box portion 3 provided with the lower flow path 32.

[0041] As shown in FIG. 3(A), the upper flow path 52 extends in the up-down direction of the figure and is composed of two upper flow paths 521 and 522 provided from the left to the right side of the figure. Note that the upper flow path 521 on the left side of the figure is configured such that the wall surface on the right side is recessed to form the opening 53.

[0042] Further, the upper flow path 521 communicates with the upper refrigerant inlet 511 on the lower side of the figure and communicates with the upper refrigerant outlet 513 on the upper side of the figure. The upper flow path 522 communicates with the upper refrigerant inlet 514 on the upper side of the figure and communicates with the upper refrigerant outlet 512 on the lower side of the figure. And on the upper side of the figure, the upper refrigerant outlet 513 and the upper refrigerant inlet 514 are connected by piping (not shown) or the like.

[0043] As a result, the refrigerant flowing in from the upper refrigerant inlet 511 provided on the lower left side of the figure flows upward from the lower side in the upper flow path 521. The refrigerant discharged from the upper refrigerant outlet 513 provided on the upper left side of the figure flows into the upper flow path 522 from the upper refrigerant inlet 514 provided on the upper right side of the figure through piping or the like. And in the upper flow path 522, the refrigerant flows downward from the upper side, and then is discharged from the upper refrigerant outlet 512 provided on the lower right side of the figure.

[0044] In this way, the refrigerant flowing through the upper flow paths 521 and 522 cools the battery module 7 placed on the upper fixing plate 9 (not shown) on the front side of the paper surface.

[0045] As shown in FIG. 3(B), it is composed of lower flow paths 321 and 322 extending in the left-right direction of the figure. The lower flow path 321 is provided on the upper side of the figure, and the lower flow path 322 is provided on the lower side of the figure. Each of the lower flow paths 321 and 322 is composed of a plurality (six in this figure) of sub-flow paths arranged side by side in the left-right direction of the figure.

[0046] The lower flow path 321 communicates with the lower refrigerant inlet 311 on the upper left side of the figure and communicates with the lower refrigerant outlet 313 on the upper right side of the figure. The lower flow path 322 communicates with the lower refrigerant inlet 312 on the lower left side of the figure and communicates with the lower refrigerant outlet 314 on the lower right side of the figure.

[0047] The six sub-channels provided in the lower flow paths 321 and 322 are connected such that the refrigerant meanders in each of the lower flow paths 321 and 322. With such a configuration, the retention of the refrigerant in the lower flow paths 321 and 322 is suppressed. Then, the battery module 7 placed on the lower fixing plate 8 (not shown) on the front side of the paper surface is cooled by the refrigerant flowing through the lower flow paths 321 and 322.

[0048] Note that the flow path as described above is an example. The upper refrigerant ports 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 ports 31 (lower refrigerant inlet 311, lower refrigerant inlet 312, lower refrigerant outlet 313, lower refrigerant outlet 314) provided in the lower box portion 3 may be either the refrigerant inlet or the outlet. 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 order of the lower refrigerant outlet 314, the upper refrigerant inlet 511, the upper refrigerant outlet 513, the upper refrigerant inlet 514, the upper refrigerant outlet 512, the lower refrigerant outlet 313, and the lower refrigerant inlet 311.

[0049] FIG. 4 is a cross-sectional view of the battery pack 100. FIG. 4(A) is a cross-sectional view taken along line I-I in FIG. 1, FIG. 4(B) is a cross-sectional view taken along line II-II, and FIG. 4(C) is a cross-sectional view taken along line III-III. In this figure, the left-right direction of the figure corresponds to the short side direction, the up-down direction of the figure corresponds to the mounting direction, and the front-back direction in the figure corresponds to the longitudinal direction.

[0050] FIG. 4(A) is a cross-sectional view of a portion in the battery pack 100 where the battery modules 7 in the lower accommodation portion 1 are stacked in one layer. FIG. 4(B) is a cross-sectional view of a portion where the lower accommodation portion 1 and the upper accommodation portion 2 are stacked and the battery modules 7 are stacked in two layers. FIG. 4(C) is a cross-sectional view of a portion where the battery modules 7 are stacked in two layers as in FIG. 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.

[0051] FIG. 4(A) shows a cross-section of the lower accommodation portion 1. The lower box portion 3 with an opening at the upper part on the upper side in the mounting direction in the drawing is formed by injection molding using aluminum or the like, and the side surface is hollow.

[0052] The bottom portion on the lower side in the drawing of the lower box portion 3 is configured such that two plate members 33 and 34 face each other in the up-down direction in the drawing with an air layer 35 therebetween. A lower flow path 32 recessed in the downward direction in the drawing is provided on the upper surface of the upper plate member 33. The lower plate member 34 is configured to have a recess similar to that of the plate member 33 so that the separation distance from the plate member 33 is constant.

[0053] In addition, between the two plate members 33 and 34, near both ends in the left-right direction in the drawing, wall portions 36 for connecting the plate members 33 and 34 in the up-down direction in the drawing are provided. Also, a wall portion 37 is provided in a region where the central lower flow path 32 is not formed. The wall portions 36 and 37 are provided in pairs in their respective regions, have a predetermined length in the up-down direction in the drawing, and extend in the front-rear direction (longitudinal direction) in the drawing.

[0054] In addition, the upper surface portion of the plate member 33 where the lower flow path 32 is not provided is closely fixed to 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 such a configuration, the battery module 7 fixed to the upper portion 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. Further, an air layer 35 is provided below the plate member 33, and since the air layer 35 has heat insulation properties, absorption of thermal energy by the refrigerant 38 flowing above the plate member 33 is suppressed. As a result, it is possible to suppress the refrigerant 38 from cooling objects other than the battery module 7, and the cooling efficiency of the battery module 7 can be improved.

[0055] FIG. 4(B) shows a cross-section of the portion where the lower housing portion 1 and the upper housing portion 2 are laminated. Regarding the lower housing portion 1, description of the portions equivalent to those shown in FIG. 4(A) is omitted. Note that, compared with FIG. 4(A), the lower box portion 3 of the lower housing portion 1 is covered by the upper flow path member 5 of the upper housing portion 2 instead of the lower cover 4.

[0056] The upper flow path member 5 is a plate-like member formed by injection molding using aluminum or the like. The bottom portion on the lower side of the upper flow path member 5 in the figure is configured such that two plate members 54 and 55 face each other with an air layer 56 therebetween, similar to the lower box portion 3. An upper flow path 52 that is recessed in the downward direction in the figure is provided on the upper surface of the upper plate member 54 on the upper side of the figure. The lower plate member 55 has a recess similar to that of the plate member 54, so that the separation distance from the plate member 54 is constant and an air layer 56 is provided between the plate members 54 and 55.

[0057] In addition, similar to the wall portions 36 and 37 provided on the wall portions 36 and 37 of the lower box portion 3 described above, wall portions 57 and 58 for connecting the two are provided between the plate members 54 and 55 of the two upper flow path members 5. Specifically, wall portions 57 are provided near both ends in the left-right direction of the figure, and wall portions 58 are provided in a region where the central upper flow path 52 is not formed. Note that the wall portions 57 and 58 are provided in pairs in their respective regions, have a predetermined length in the up-down direction of the figure, and extend in the front-rear direction (longitudinal direction) of the paper surface in the figure.

[0058] Further, the upper surface portion of the plate member 54 where the lower flow path 32 is not provided is closely fixed to the upper fixing 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 fixing plate 9. Due to such a configuration, the battery module 7 fixed to the upper part of the upper fixing plate 9 is cooled by the refrigerant 38 flowing between the upper flow path 52 and the upper fixing plate 9. Also, an air layer 35 is provided below the plate member 54, and since the air layer 35 has heat insulation properties, absorption of thermal energy into the refrigerant 38 flowing above the plate member 54 is suppressed. As a result, it is possible to suppress the refrigerant 38 from cooling objects other than the battery module 7, and the cooling efficiency of the battery module 7 can be improved.

[0059] FIG. 4(C) shows a cross section at a portion where the lower accommodation portion 1 and the upper accommodation portion 2 are laminated, at a position different from that in FIG. 4(B). In this figure, for the lower accommodation portion 1 and the upper accommodation portion 2, descriptions of portions equivalent to the configurations shown in FIGS. 4(A) and 4(B) are omitted.

[0060] The upper accommodation portion 2 in this figure, when compared with the configuration shown in FIG. 4(B), has openings 53 and 91 that communicate the inside of the lower box portion 3 and the inside of the upper box portion 6 near the center in the left - right direction of the figure. Details of the configurations of these openings 53 and 91 will be described with reference to FIG. 5.

[0061] FIG. 5 is an enlarged view of the vicinity of the openings 53 and 91 provided in the upper box portion 6.

[0062] As shown in this figure, in the upper - side plate member 54 of the plate members 54 and 55 in the drawing, an end portion 54E is formed by cutting out the vicinity of the center in the short - hand (left - right in the drawing) direction.

[0063] Furthermore, in the plate member 55 on the lower side of the figure, the vicinity of the center in the left - right direction of the figure is broken, and further, the tip formed by the break is bent upward in the figure, thereby forming the end portion 55E. Here, the end portion 55E is configured to be separated by a predetermined distance from the end portion 54E of the plate member 54 on the side surface in the left - right direction of the figure, that is, the surface that does not face the opening 53. As will be described later, the end portion 9E of the upper - stage fixing plate 9 is disposed in the separation portion between the end portions 54E and 55E.

[0064] In the upper - stage fixing plate 9, the vicinity of the center in the left - right direction of the figure is broken, and further, the tip formed by the break is bent downward in the figure, thereby forming the end portion 9E. The end portion 9E is disposed so as to be inserted between the end portion 54E of the plate member 54 and the end portion 55E of the plate member 55. And the tip of the end portion 55E of the plate member 55 is welded to the surface facing the opening 53 of the end portion 9E of the upper - stage fixing plate 9.

[0065] With such a configuration, the air layer 56 provided between the plate members 54 and 55 is separated so as not to communicate with the inside of the lower - stage box portion 3 that houses the battery module 7 of the lower - stage housing portion 1 and the inside of the upper - stage box portion 6 that houses the battery module 7 of the upper - stage housing portion 2. Since the air layer 56 does not mix with the air inside the lower - stage box portion 3 and the upper - stage box portion 6, which becomes relatively high temperature due to the heat generation of the battery module 7, it is kept at a relatively low temperature. As a result, the refrigerant 38 is suppressed from absorbing thermal energy from the side of the plate member 54. Thereby, it is possible to prevent the refrigerant 38 from cooling objects other than the battery module 7, and it is possible to improve the cooling efficiency of the battery module 7.

[0066] In the above - described embodiment, the air layers 35 provided between the plate members 33 and 34 and the air layer 56 provided between the plate members 54 and 55 are used as heat - insulating members, but it is not limited to this. A heat - insulating layer may be formed by filling a gas such as nitrogen, evacuating, or filling a foaming material such as urethane between the plate members 33 and 34.

[0067] According to this embodiment, the following effects can be obtained.

[0068] According to the battery pack 100 of this embodiment, the lower accommodation part 1 and the upper accommodation part 2 that accommodate the battery module 7 are provided with bottoms (the bottom of the lower box part 3, 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. And inside those bottoms, there are provided a lower flow path 32 and an upper flow path 52, and air layers 35, 56 having heat insulation properties, respectively. The air layers 35, 56 are provided on the side opposite to the side on which the battery module 7 is placed with respect to the lower flow path 32 and the upper flow path 52.

[0069] With such a 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 to the upper surface of the bottom. At the same time, air layers 35, 56 having heat insulation properties are provided below the lower flow path 32 and the upper flow path 52 at the bottom, and the absorption of thermal energy into the refrigerant 38 from the side opposite to the side where the battery module 7 is provided is prevented. Therefore, it is possible to prevent the refrigerant 38 from cooling objects other than the battery module 7, and the cooling efficiency of the battery module 7 can be improved.

[0070] According to the battery pack 100 of this embodiment, the lower accommodation part 1 (the first accommodation part) and the upper accommodation part 2 (the second accommodation part) are laminated via the bottom of the upper accommodation part 2 (the upper flow path member 5 and the upper fixing plate 9). And openings 53, 91 for communicating the inside of the lower accommodation part 1 and the inside of the upper accommodation part 2 are provided in the bottom. Cables connecting the battery module 7 accommodated in the lower accommodation part 1 and the battery module 7 accommodated in the upper accommodation part 2 pass through the openings 53, 91. By having such a configuration, the integration density of the battery module 7 can be improved, and thus the battery pack 100 can be miniaturized.

[0071] According to the battery pack 100 of the present embodiment, in the bottom part (the upper flow path member 5 and the upper fixing plate 9) of the upper accommodation part 2, the air layer 35 which is a heat insulation part, and the openings 53 and 91 are separated from each other without communicating with each other by providing the end parts 9E and 55E.

[0072] With such a configuration, since the air layer 56 does not mix with the air in the lower box part 3 and the upper box part 6 which become relatively high temperature due to the heat generation of the battery module 7, it is kept at a relatively low temperature. Therefore, in the refrigerant 38, absorption of thermal energy from the side of the plate member 54 where the battery module 7 is not provided is suppressed. As a result, it is possible to prevent the refrigerant 38 from cooling objects other than the battery module 7, and it is possible to improve the cooling efficiency of the battery module 7.

[0073] As described above, the embodiments, the above embodiments and the modified examples of the present invention only show a part 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 embodiments.

Explanation of reference numerals

[0074] 1 Lower accommodation part 2 Upper accommodation part 3 Lower box part 5 Upper flow path member 7 Battery module 8 Lower fixing plate 9 Upper fixing plate 35 Air layer 53, 91 Openings 100 Battery pack

Claims

1. A battery pack having a rechargeable battery module and a housing portion for housing the battery module, wherein the housing portion has a bottom portion on which the battery module is placed, the bottom portion, has a flow path portion through which a refrigerant for cooling the battery module flows, and a heat insulating portion provided on a side opposite to the side on which the battery module is placed with respect to the flow path portion, wherein the flow path portion and the heat insulating portion are arranged adjacent to each other, the flow path portion, includes a first plate-like member that contacts the battery module, and a second plate-like member connected to an opposite surface that is opposite to the surface of the first plate-like member that contacts the battery module, wherein in the second plate-like member, both end portions in the 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 the refrigerant flows, the heat insulating portion is arranged adjacent to the second plate-like member and covers the entire central portion, the flow path is arranged such that in a plan view, an outer shape of the flow path in the width direction is accommodated inside an outer shape of the battery module in the width direction. A battery pack.

2. The battery pack according to claim 1, wherein the housing portion is composed of a first housing portion and a second housing portion, and the first housing portion and the second housing portion are stacked in this order in the placement direction, the battery module, includes a first battery module housed in the first housing portion, and a second battery module housed in the second housing portion, the bottom portion, includes 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. A battery pack.

3. The battery pack according to claim 2, the second bottom portion, includes a first region that accommodates the flow path portion and the heat insulating portion inside in a plan view, and a second region that is outside the first region in a plan view, wherein a communication hole that communicates the first housing portion and the second housing portion is formed in the second region, and a cable that electrically connects the first battery module and the second battery module is inserted through the communication hole. A battery pack.

4. The battery pack according to claim 3, wherein the heat insulating portion is configured as an air layer, and the air layer is separated so as not to communicate with the communication hole. A battery pack.

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