Power storage device

Abstract

Provided is a power storage device wherein direct cooling with a cooling medium can be performed throughout a specific region of one side surface of a case to be cooled.　In this power storage device that accommodates, in a case, both a layered cell in which a plurality of power storage cells are layered and an electric component wired to the layered cell, at least one side surface of the case is a planar first side surface, a cooling plate is joined to an outer surface of a specific region of the first side surface, the cooling plate has a general surface and a protuding, extending groove section, and a cooling flow path is formed by the groove section and the outer surface of the first side surface.

Description

Power storage device

[0001] The present invention relates to an electricity storage device.

[0002] Electricity storage devices are installed as power sources in, for example, electric vehicles, hybrid vehicles, and the like, and are capable of outputting large currents. In these electricity storage devices, a plurality of electricity storage cells are stacked in a stacking direction to form stacked cells, and the stacked cells are housed and fixed in a case directly or as modular units. A cooling structure is used for the purpose of forcibly cooling the stacked cells that generate heat within the case. A typical cooling structure, for example, as disclosed in Patent Document 1 (JP 2023-12176 A), is a structure in which a cooler, which is an independent volumetric housing, is attached to the bottom of the case via a heat transfer member, and water, which serves as a cooling medium, is circulated within the cooler.

[0003] However, installing a cooler, which is an independent volumetric component, alongside the case is undesirable in terms of cost and weight. Furthermore, heat transfer between separate components is hindered (high thermal resistance), and the need for a heat transfer member to fill minute irregularities and ensure contact area makes it difficult to reduce thermal resistance. Therefore, Patent Document 2 (Patent Registration No. 7167103) proposes fixing a cooler (cooling mechanism 400) to the bottom of the case 200. The cooling mechanism 400, which is a box that forms the cooling flow path, does not have a top cover. Instead, the bottom of the case 200 seals the cooling medium. In other words, the cooling medium, water, directly contacts the bottom of the case 200, reducing thermal resistance.

[0004] Similarly, Patent Document 3 (Patent Registration No. 7097975) proposes fixing a cooler in direct contact with the bottom of the case. The resin plate 2 that forms the cooling flow path does not have a top cover, and instead the metal case bottom 3 seals the coolant. The case bottom 3 is surface-modified before the resin plate is welded. This also reduces thermal resistance because the coolant comes into direct contact with the bottom of the case.

[0005] Japanese Patent Application Laid-Open No. 2023-12176 Patent Registration No. 7167103 Patent Registration No. 7097975

[0006] However, these cooling devices require the cooling device, which is an independent volumetric housing, to be tightly attached to the entire bottom surface of the case, which requires increased strength of the cooling device as a housing and requires complex means for tight attachment, resulting in high costs and manufacturing difficulties. Furthermore, there is a concern about malfunctions due to differences in thermal expansion between the bottom surface of the case and the cooling device. Furthermore, since the cooling device must be tightly attached to the entire side of the case, it is necessary to cool areas of the case that do not particularly require cooling, resulting in unnecessary cooling in areas that do not require cooling. In other words, there is a need in the technical field for a technology that can directly cool one side of the case with a cooling medium over a specific area of ​​that side.

[0007] In view of the above-mentioned problems, an object of the present invention is to provide an electricity storage device that can directly cool a specific region on one side of a case that is desired to be cooled with a cooling medium.

[0008] In order to solve the above problems, the energy storage device of the present invention is an energy storage device in which a stacked cell formed by stacking a plurality of energy storage cells and electrical components connected to the stacked cell are housed together in a case, at least one side of the case is a first side having a planar specific area, a cooling plate is joined to the outer surface of the specific area on the first side, the cooling plate has a general surface and a groove portion protruding and extending from the general surface, and a cooling flow path is formed by the groove portion and the outer surface of the first side.

[0009] According to the present invention, a cooling plate is joined only to a specific planar region of the first side surface, and the cooling plate and the specific region form a refrigerant flow path, allowing the refrigerant to directly contact the specific region, thereby enabling cooling of only the desired area with low thermal resistance. Furthermore, the cooling plate functions as a reinforcing material that improves the surface rigidity of the first side surface, allowing the thickness of the first side surface and the cooling plate to be reduced, thereby achieving weight reduction and heat mass reduction. The cooling plate can be made of the same metal as the first side surface, which facilitates joining the two. The entire outer periphery of the general surface of the cooling plate is joined to the first side surface in a liquid-tight manner. The joining method is not particularly limited, but a method that allows continuous welding, such as arc welding, can be used.

[0010] Another aspect of the present invention is defined as follows. That is, in the energy storage device defined in the first aspect, the first side surface has an overhang portion that protrudes more than an adjacent side surface, both ends of the cooling plate are located in the overhang portion, and both ends are provided with a coolant inlet and outlet portion. In the invention defined in this way, the coolant inlet and outlet portions are provided in the overhang portion, and the coolant can be introduced into and discharged from the overhang portion into the cooling flow path. This allows the coolant piping connected to the inlet and outlet portions to be concentrated on one side of the case, thereby making the case more compact.

[0011] In the above, all of the stacked cells are housed within the specific region. In the first aspect, relatively heat-resistant components, such as electrical components, can be placed in regions other than the specific region. Alternatively, high-heat-generating components for which the cooling plate's cooling capacity is insufficient may be placed (in this case, a separate cooling device is provided). In either case, it is preferable to prevent or reduce thermal interference between the specific region and regions other than the specific region. Therefore, by arranging a cooling flow path between the specific region and a region other than the specific region where other components (such as electrical components) are placed, it is possible to prevent or reduce thermal interference between the two regions. To achieve this, it is preferable to arrange a cooling water channel in the specific region so that it follows the other components. To introduce fresh cooling medium into such a cooling water channel, it is preferable to attach a portion that continues from the cooling medium inlet.

[0012] It is a bottom perspective view of the electric storage device according to the first embodiment of the present invention.It is a cross-sectional view of the inlet / outlet part of the cooling plate of the electric storage device according to the first embodiment of the present invention.

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will now be described with reference to FIGS.

[0014] FIG. 1 is a schematic bottom perspective view showing an example of the configuration of the energy storage device 1. When the energy storage device 1 is mounted on a vehicle or the like and in an operating position, a first side surface 5 of the case 2 is positioned vertically downward. That is, the first side surface 5 is the bottom surface of the case 2. The case 2 has a box-like shape, and a side surface serving as a lid on the top surface opposite the first side surface 5 is not shown in the figure. The case 2 also has four side surfaces, of which a second side surface 6 and a third side surface 7 are shown in the figure. All of the side surfaces of the case 2 are made of rigid plate materials such as metal or resin, and are combined to ensure airtightness to form a housing. It is preferable that at least the side surface to which the cooling plate 9 (described later) is joined is made of metal. In this embodiment, the first side surface is made of metal as an example. Furthermore, when multiple side surfaces are made of metal, the side surfaces may be assembled together using a panel joining method, or integral molding by press working, casting, or the like may be used.

[0015] A plurality of stacked cell rows 3 (four in this embodiment) are housed side by side in the case 2 and are wired to one another. Next to the stacked cell rows 3, electrical components 4 are also arranged, which are wired to the stacked cell rows 3 and have functions such as power input / output control. The stacked cell rows 3 may be a stack of cells only, or a modular stack in which the cells are constrained in fixed units. The stacked cell rows 3 may require forced cooling to maintain an appropriate temperature during operation. On the other hand, the electrical components 4 often do not necessarily require forced cooling. The four stacked cell rows 3 and the electrical components 4 are mounted on a first side 5, which is the underside of the case 2, via a heat transfer member (not shown), but the heat transfer member is not essential.

[0016] The entire outer periphery of a metal cooling plate 9 is liquid-tightly joined to the planar specific region on the first side surface 5 by laser welding, a type of linear joining method. In other words, the specific region is the region facing the cooling plate 9 on one side surface 5. In this embodiment, the cooling plate 9 is made of metal as an example, but it may be a separate member, and the linear joining method is not limited to laser welding. The specific region is a region in which the stacked cell row 3 exists and is a region that requires forced cooling. The region to which the cooling plate 9 is not joined is a non-cooling region 8, which corresponds to a region in which electrical components 4 that do not require forced cooling exist. If forced cooling of the electrical components 4 is also required, the non-cooling region 8 may be eliminated and the specific region may be expanded.

[0017] The cooling plate 9 has a flat general surface 11 and grooves 10 extending downward from the general surface 11 as convex portions. The grooves 10 meander across the entire surface of the specific region, with coolant inlet ports 12 and outlet ports 13 at both ends. Thus, the grooves 10 and the first side surface 5 form a meandering, unicursal coolant flow path. However, the shape of the grooves 10, i.e., the flow path, within the specific region can be arbitrarily configured. In this example, a portion of the grooves 10 (cooling water channels) of the cooling plate 9 is positioned along the non-cooled region 8. This prevents or reduces thermal interference between the specific region requiring cooling and the non-cooled region 8. The grooves are preferably located upstream of the coolant flow to increase the efficiency of preventing thermal interference between the two regions. To further increase the efficiency of preventing thermal interference, it is preferable to extend the grooves vertically from the third side surface 7 and minimize the distance from the coolant inlet ports.

[0018] In this embodiment, the linear joining of the metal cooling plate 9 to the specific metal region is performed by continuous linear joining (e.g., laser welding) on ​​the general surface 11 around the entire periphery of the cooling plate 9 to liquid-tightly join the general surface 11 and the specific metal region of the first side surface 5. Linear joining is also performed on the general surface 11 between the serpentine grooves 10 to prevent short-circuiting of the coolant between adjacent grooves 10. For two-dimensional continuous linear joining of metals, laser welding using a robotic welder is preferred, but alternative methods such as roll seam welding may also be selected as appropriate. Of course, if a material other than metal is selected for the side surface or cooling plate, any suitable joining method, including adhesive bonding or brazing, may be selected as appropriate. In other words, any linear joining method is acceptable as long as continuous linear joining is possible and the specific region of the first side surface 5 can be liquid-tightly fixed to the general surface 11 of the cooling plate 9.

[0019] FIG. 2 is a cross-sectional view of the coolant inlet 12 and outlet 13 provided at both ends of the groove 10. Through-hole laser welds 15, 16 are applied to the general surface 11 on both sides of the groove 10, and the cooling plate 9 is welded to the overhang 14 of the first side surface 5. The pipe-shaped inlet 12 and outlet 13 are fitted into holes in the first side surface 5 and fixed liquid-tightly by a circumferential joint 17. The circumferential joint 17 may be laser welded, TIG / MIG welded, brazed, or adhesive. With this structure, the coolant flows into the groove 10 from one connecting portion, absorbs heat from the first side surface 5 as it passes through the meandering flow path, and is then discharged from the other connecting portion. In this way, cooling within the specific region is ensured.

[0020] The overhang portion 14 of the first side surface 5 is a portion of the first side surface 5 that protrudes relative to the adjacent third side surface 7. In other words, the third side surface 7 is recessed relative to the first side surface 5, creating a space. Within the space of the overhang portion 14, connection portions 12 and 13 for the refrigerant flow path are installed approximately parallel to the third side surface 7, and cooling medium piping (not shown) is connected. Either of the connection portions 12 and 13 may be selected as the cooling medium inlet and outlet ports. In this example, the side closer to the non-cooling region can be used as the outlet port 13, and the side further away can be used as the inlet port 12. This allows the connection portions 12 and 13 to be contained within the overhang portion 14 and not protrude from the outer periphery of the case 2, making it easier to avoid interference with peripheral components. In this example, the overhang portion 14 is provided on one side of the case 2, where components for introducing and discharging the cooling medium are arranged. This allows the width of the case 2 to be narrower than in a structure in which such components are arranged on both sides of the case 2.

[0021] With the above-described configuration, in the present invention, only the first side surface 5 (and the heat transfer member, if necessary) exists between the stacked cell row 3 and the cooling medium, making it possible to cool the stacked cell row 3 with minimal thermal resistance. Furthermore, the area to be cooled can be set as desired.

[0022] For the purpose of explaining the present invention, an embodiment having a specific configuration has been described above with reference to the accompanying drawings. However, the scope of the present invention should not be construed as being limited to this embodiment, and it goes without saying that appropriate modifications can be made within the scope of the claims and the matters described in the specification.

[0023] DESCRIPTION OF SYMBOLS 1 Energy storage device 2 Case 3 Stacked cell row 4 Electrical component 5 First side surface 6 Second side surface 7 Third side surface 8 Non-cooled area 9 Cooling plate 10 Groove portion 11 General surface 12 Inlet portion 13 Outlet portion 14 Overhang portion

Claims

1. A power storage device that houses a stacked cell formed by stacking a plurality of power storage cells and electrical components connected to the stacked cell in a case, at least one side surface of the case is a planar region facing a cooling plate, and includes a specific region where the stacked cell that requires cooling is located, and a non-specific region where the electrical components that do not require cooling are located, which is a first side surface, the cooling plate is liquid-tightly joined to the outer surface of the specific region on the first side surface by a linear joining method, the cooling plate has a general surface and a groove portion that extends as a convex portion protruding outward from the general surface, the groove portion, extends in a meandering manner across the entire surface of the specific region, and the general surfaces between the meandering groove portions are liquid-tightly joined by the linear joining method, a cooling flow path is formed between the groove portion and the outer surface of the specific region, A power storage device characterized by the above.

2. The specific region includes at least the storage range of the stacked cell, The power storage device according to claim 1.

3. The cooling plate and the first side surface are made of the same kind of metal, the entire outer periphery of the general surface of the cooling plate is liquid-tightly joined to the outer surface of the first side surface, The power storage device according to claim 1 or 2.

4. The first side surface has an overhang portion that protrudes more than the adjacent side surfaces, both ends of the cooling plate are located at the overhang portion, a cooling medium introduction portion and a discharge portion are provided at both ends, The power storage device according to claim 1.

5. The discharge portion of the cooling medium is arranged at a position closer to the electrical component than the introduction portion, The power storage device according to claim 4.

6. A cooling flow path following the discharge portion is arranged along the electrical component, The power storage device according to claim 5.

7. The cooling flow path following the discharge portion is perpendicular to the side surface adjacent to the one side surface of the case, The power storage device according to claim 6.

8. A power storage device that houses a stacked cell formed by stacking a plurality of power storage cells and electrical components connected to the stacked cell in a case, at least one side surface of the case is a planar region facing a cooling plate, and includes a specific region where the stacked cell that requires cooling is located, and a non-specific region where the electrical components that do not require cooling are located, which is a first side surface, A side surface extending in a direction intersecting the first side surface, the side surface having a side end surface positioned inward from an edge of the first side surface; comprising; the cooling plate has a general surface and a groove portion protruding and extending from the general surface; a cooling flow path is formed at an outer surface of the groove portion and the first side surface; the first side surface has an overhang portion that constitutes a part of a space formed to protrude relatively outward from the side surface; both end portions of the cooling plate are positioned at the overhang portion; a cooling medium introduction portion and a discharge portion are provided along a plane of the overhang portion at both end portions; A power storage device characterized by the above.