Energy storage device

Abstract

To provide a power storage device that can efficiently release heat from a power storage element unit to the outside.SOLUTION: A power storage device 1 includes a power storage element unit 101 having one or more power storage elements 100, and an exterior body 10 that houses the power storage element unit 101. The exterior body 10 includes a bottom wall unit 13 facing the power storage element unit in a first direction (Z-axis direction), and a side wall unit 14 facing the power storage element unit in a second direction (Y-axis direction) intersecting the Z-axis direction. The side wall unit 14 includes a plurality of first fins 51 on an inner surface 14a facing the power storage element unit 101, each of which projects toward the power storage element unit 101 and extends along the Z-axis direction.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a power storage device including a power storage element and an exterior body that houses the power storage element.

Background Art

[0002] The assembled battery module disclosed in Patent Document 1 includes a plurality of secondary batteries, a housing made of aluminum die-cast, and a non-conductive lid. The housing includes a plurality of heat dissipation fins on the surfaces of a pair of opposing second wall portions. Each of the plurality of heat dissipation fins has a shape extending parallel to the insertion direction of the plurality of secondary batteries into the housing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described conventional assembled battery module, each of the plurality of heat dissipation fins is disposed on the outer surface of the second wall portion of the housing so as to contact the air outside the housing, thereby improving the heat dissipation performance of the assembled battery module. However, in this assembled battery module, secondary batteries are housed in each of the plurality of housing portions of the housing, and an opening (an opening of the housing) for exposing the terminal surfaces of the plurality of secondary batteries to the outside is covered by the lid. In this case, for example, there arises a problem that heat generated from the plurality of secondary batteries (power storage elements) tends to stay inside the housing. This is not preferable from the viewpoint of efficiently discharging the heat generated by the plurality of power storage elements to the outside of the housing.

[0005] The present invention was made by the inventor of the present application in light of the above-mentioned problems, and aims to provide an energy storage device comprising an energy storage element unit having one or more energy storage elements, which can efficiently dissipate heat from the energy storage element unit to the outside. [Means for solving the problem]

[0006] An energy storage device according to one aspect of the present invention comprises an energy storage element unit having one or more energy storage elements, and an outer casing housing the energy storage element unit, wherein the outer casing has a bottom wall portion facing the energy storage element unit in a first direction, and a side wall portion facing the energy storage element unit in a second direction intersecting the first direction, and the side wall portion has a plurality of first fins on its inner surface facing the energy storage element unit, each of which protrudes toward the energy storage element unit and extends along the first direction. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an energy storage device that can efficiently release heat from an energy storage element unit to the outside. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view showing the external appearance of the energy storage device according to the embodiment. [Figure 2] This is an exploded perspective view of the energy storage device according to the embodiment. [Figure 3] This is a cross-sectional view showing the structural relationship between the first fin, the second fin, and the energy storage element unit according to the embodiment. [Figure 4] This is a plan view showing the structural relationship between the first fin, the second fin, and the energy storage element unit according to the embodiment. [Figure 5A] This diagram shows the relative sizes of the first heat conductive member and the second heat conductive member according to the embodiment. [Figure 5B] This is a plan view showing the first heat conduction member, which is formed from a single metal plate. [Figure 6]This is a cross-sectional view showing the structural relationship between the first fin, the second fin, and the energy storage element unit according to a modified example 1 of the embodiment. [Figure 7] This is a cross-sectional view showing the structural relationship between the first fin, the second fin, and the energy storage element unit according to a modified example 2 of the embodiment. [Figure 8] This is a cross-sectional view showing the heat conductive member according to a modified example 2 of the embodiment separated from the outer casing. [Modes for carrying out the invention]

[0009] An energy storage device according to one aspect of the present invention comprises an energy storage element unit having one or more energy storage elements, and an outer casing housing the energy storage element unit, wherein the outer casing has a bottom wall portion facing the energy storage element unit in a first direction, and a side wall portion facing the energy storage element unit in a second direction intersecting the first direction, and the side wall portion has a plurality of first fins on its inner surface facing the energy storage element unit, each of which protrudes toward the energy storage element unit and extends along the first direction.

[0010] In this configuration, the side wall has multiple first fins, which increases the contact area with the gas (air) inside the outer casing. As a result, the amount of heat absorbed by the side wall from the heat storage element unit increases. Consequently, the heat generated by the heat storage element unit can be efficiently released (dissipated) to the outside of the outer casing via the side wall. Furthermore, since energy storage devices are generally positioned with the bottom wall facing downwards, the direction in which the multiple first fins extend is vertical. As a result, the multiple first fins do not easily resist the flow of hot air moving from bottom to top. In other words, the multiple first fins are positioned in a way that does not easily obstruct the flow of air whose temperature has risen due to the heat from the energy storage element unit. This makes it easier for air to flow inside the outer casing, and as a result, the heat from the energy storage element unit can be efficiently transferred to the side wall by convection. Thus, according to this embodiment of the energy storage device, the heat generated by the energy storage element unit can be efficiently released to the outside.

[0011] The side wall portion may further consist of a plurality of second fins arranged on the outer surface opposite to the inner surface, each having a plurality of second fins extending in a direction along the outer surface.

[0012] This configuration increases the contact area between the side wall and the gas (air) outside the outer casing. As a result, the heat absorbed on the inner surface, which has multiple first fins, can be efficiently released by the multiple second fins provided on the outer surface.

[0013] Each of the aforementioned plurality of second fins may extend in a third direction that intersects the first direction and the second direction.

[0014] Energy storage devices are generally positioned with their bottom walls facing downwards. In this case, the second fins, which are exposed to the outside air of the outer casing, are positioned to extend laterally. Therefore, when the energy storage device is mounted on a mobile device, or when it is installed in a location where it is exposed to horizontally flowing air, the air flows along the second fins, efficiently cooling the side walls. Consequently, the heat dissipation efficiency of the heat generated by the energy storage element unit can be further improved.

[0015] The plurality of first fins are provided on a first heat conductive member fixed to the inner surface of the side wall, and the plurality of second fins are provided on a second heat conductive member fixed to the outer surface of the side wall, and when viewed from the second direction, the second heat conductive member may be formed to be larger in size than the first heat conductive member.

[0016] With this configuration, the member having multiple fins can be manufactured separately from the side wall, making it easier to manufacture an exterior body with multiple fins than, for example, when the multiple fins are formed integrally with the side wall. Furthermore, since the second heat conductive member on the outer surface is larger than the first heat conductive member on the inner surface, the second heat conductive member can more reliably receive the heat absorbed by the first heat conductive member, and as a result, the heat inside the exterior body can be released to the outside of the exterior body more efficiently.

[0017] Hereinafter, with reference to the drawings, a power storage device according to an embodiment (including its modified examples) of the present invention will be described. Each of the embodiments described below shows comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, manufacturing processes, order of manufacturing processes, etc. shown in the following embodiments are merely examples and are not intended to limit the present invention. In each figure, dimensions and the like are not strictly shown as they are. Further, in each figure, the same or similar components are denoted by the same reference numerals.

[0018] In the following description and drawings, the short side direction of the exterior of the power storage device or the opposing direction of the short side surfaces of the power storage elements is defined as the X-axis direction. The longitudinal direction of the exterior of the power storage device or the arrangement direction of a plurality of power storage elements is defined as the Y-axis direction. The arrangement direction of the main body and the lid of the exterior of the power storage device or the vertical direction is defined as the Z-axis direction. These X-axis direction, Y-axis direction, and Z-axis direction are directions that intersect (orthogonal in this embodiment) with each other. Although the Z-axis direction may not be the vertical direction depending on the usage mode, hereinafter, for the convenience of explanation, the Z-axis direction will be described as the vertical direction.

[0019] In the following description, for example, the X-axis plus direction indicates the arrow direction of the X-axis, and the X-axis minus direction indicates the direction opposite to the X-axis plus direction. The same applies to the Y-axis direction and the Z-axis direction. Merely stating "X-axis direction" means a bidirectional or one-way direction parallel to the X-axis. The same applies to terms related to the Y-axis and Z-axis.

[0020] Furthermore, expressions indicating relative directions or postures such as parallel and orthogonal include cases where they are not strictly in that direction or posture. For example, when it is said that two directions are orthogonal, it means not only that the two directions are completely orthogonal but also that they are substantially orthogonal, that is, for example, including a difference of about several percent. In the following description, when the expression "insulation" is used, it means "electrical insulation".

[0021] (Embodiment) [1. General explanation of energy storage devices] First, the general configuration of the energy storage device 1 in this embodiment will be described. Figure 1 is a perspective view showing the external appearance of the energy storage device 1 according to this embodiment. Figure 2 is an exploded perspective view of the energy storage device 1 according to this embodiment. Inside the outer casing 10, in addition to the components shown in Figures 2 and later, busbars and electrical equipment are housed, and spacers arranged along the energy storage elements 100, and restraining members that restrain the multiple energy storage elements 100 may also be arranged. However, the illustration and description of these components will be omitted as appropriate.

[0022] The energy storage device 1 is a device that can charge electricity from an external source and discharge electricity to the outside, and in this embodiment, it has a substantially rectangular parallelepiped shape. The energy storage device 1 is, for example, a battery module (battery pack) used for power storage or power supply purposes. Specifically, the energy storage device 1 is used as a battery for driving or starting the engine of mobile vehicles such as automobiles, motorcycles, watercraft, ships, snowmobiles, agricultural machinery, construction machinery, or railway vehicles for electric railways. Examples of automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicles. Examples of railway vehicles for electric railways include electric trains, monorails, linear motor cars, and hybrid trains equipped with both diesel engines and electric motors. The energy storage device 1 can also be used as a stationary battery for household or commercial use.

[0023] As shown in Figures 1 and 2, the energy storage device 1 comprises an outer casing 10 and an energy storage element unit 101 housed within the outer casing 10. The outer casing 10 is a box-shaped (approximately rectangular parallelepiped) container (module case) that constitutes the housing of the energy storage device 1. In other words, the outer casing 10 is positioned outside the energy storage element unit 101 and protects the energy storage element unit 101 from impacts and the like. In this embodiment, the outer casing 10 is made of a metal such as iron, aluminum, or an aluminum alloy. In addition to metal, resin and the like can also be used as the material for forming the outer casing 10. Examples of such resins include polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), polyamide (PA), ABS resin, or composite materials thereof.

[0024] The exterior body 10 comprises an exterior body 12 that constitutes the main body of the exterior body 10 and a lid 11. The exterior body 12 is a bottomed rectangular cylindrical housing having a bottom wall portion 13 at one end in the Z-axis direction, an opening 12a at the other end in the Z-axis direction, and side wall portions 14 at each end in the Y-axis direction.

[0025] The side wall portion 14 of the exterior body 12 according to this embodiment has a plurality of first fins 51 provided on the inner surface 14a of the side wall portion 14, the plurality of first fins 51 protruding toward the energy storage element unit 101. The side wall portion 14 further has a plurality of second fins 61 arranged on the outer surface 14b of the side wall portion 14. In this embodiment, the plurality of first fins 51 are provided on a first heat conductive member 50 fixed to the inner surface 14a of the side wall portion 14, and the plurality of second fins 61 are provided on a second heat conductive member 60 fixed to the outer surface 14b of the side wall portion 14. The configuration of the side wall portion 14 having the plurality of first fins 51 and the plurality of second fins 61 and its surrounding area will be described later with reference to Figures 3 to 5A.

[0026] The cover 11 is a rectangular member that closes the opening 12a of the outer casing body 12. The cover 11 and the outer casing body 12 are joined together by fastening with bolts and nuts (not shown) with a gasket interposed between them. If the cover 11 and the outer casing body 12 are made of resin such as PC, the cover 11 and the outer casing body 12 may be joined by adhesive, heat sealing, or ultrasonic welding. The cover 11 is provided with, for example, an exhaust pipe (not shown), and when gas is discharged from the gas discharge section 105 of the energy storage element 100, the gas inside the outer casing 10 is discharged to the outside of the outer casing 10 via the exhaust pipe. The joint between the outer casing body 12 and the cover 11 has relatively high airtightness due to the placement of the gasket as described above. Therefore, when gas is discharged from the energy storage element 100, gas leakage from the joint is suppressed. The cover 11 is provided with a pair of external terminals 19, which are a pair of module terminals for the positive and negative electrodes. The energy storage device 1 charges with electricity from the outside and discharges electricity to the outside through this pair of external terminals 19. The external terminals 19 are formed of a conductive metal material such as aluminum, aluminum alloy, copper, or copper alloy. In this embodiment, when the outer casing 10 is made of metal, the external terminals 19 are fixed to the cover 11 of the outer casing 10 via an insulating material (not shown), such as a resin terminal block.

[0027] The energy storage element unit 101 is a group of energy storage elements 100 composed of one or more energy storage elements 100. In this embodiment, the energy storage element unit 101 is composed of eight energy storage elements 100, and the eight energy storage elements 100 are arranged in the Y-axis direction with their long side surface 110a facing the Y-axis direction. The energy storage element unit 101 may have spacers or holders (not shown) arranged along the sides of the energy storage elements 100. The energy storage element unit 101 may have restraining members (not shown) that restrain the multiple energy storage elements 100 in their alignment direction. The energy storage element unit 101 may have a container for housing the group of energy storage elements 100 separately from the outer casing 10. In this case, the energy storage element unit 101 having a container for housing the group of energy storage elements 100 is housed in the outer casing 10. The eight energy storage elements 100 of the energy storage element unit 101 are connected, for example, in series by a plurality of busbars (not shown). The electrical connection configuration of the eight energy storage elements 100 is not limited to this. For example, four groups of energy storage elements 100, each consisting of two energy storage elements 100 connected in parallel, may be formed, and these four groups of energy storage elements 100 may be connected in series using multiple busbars.

[0028] The energy storage element 100 is a secondary battery (single cell) capable of charging and discharging electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. As shown in Figure 2, the energy storage element 100 comprises a flat rectangular parallelepiped (square) shaped container 110, and inside the container 110 are electrodes, a current collector, and an electrolyte (not shown). As the electrodes, for example, a wound-type electrode is used, which is formed by winding together layers of electrodes with a separator sandwiched between a positive electrode plate and a negative electrode plate. Examples of electrodes for the energy storage element 100 include a wound-type electrode, a stacked electrode formed by stacking multiple flat electrode plates, and a bellows-type electrode formed by folding electrode plates in a bellows-like manner. As for the electrolyte contained in the container 110, there are no particular restrictions on the type as long as it does not impair the performance of the energy storage element 100, and various types can be selected. The energy storage element 100 is not limited to a non-aqueous electrolyte secondary battery, but may be a secondary battery other than a non-aqueous electrolyte secondary battery, or a capacitor. The energy storage element 100 may not be a secondary battery, but a primary battery that allows the user to use the stored electricity without charging. The energy storage element 100 may be a pouch-type energy storage element. The energy storage element 100 may be a battery using a solid electrolyte. The shape of the energy storage element 100 is not limited to the above-mentioned prismatic shape, but may be other polygonal prism shapes, cylindrical shapes, elliptical prism shapes, oblong cylindrical shapes, etc.

[0029] As shown in Figure 2, the container 110 is a rectangular parallelepiped case having a pair of long sides 110a, a pair of short sides 110b, a bottom surface 110d, and a terminal arrangement surface 110c. The terminal arrangement surface 110c is provided with a pair of electrode terminals 120 and a gas discharge section 105. The container 110 having such a configuration is designed so that after housing the electrode body and the like inside the container body which forms the parts other than the terminal arrangement surface 110c, the inside can be sealed by welding the container body and the lid plate which forms the terminal arrangement surface 110c together. The material of the container 110 is not particularly limited, but it is preferable to use a weldable metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet.

[0030] The electrode terminals 120 are terminal members that are electrically connected to the electrode body housed in the container 110, and are provided protruding from the terminal arrangement surface 110c. One of the pair of electrode terminals 120 is electrically connected to the positive electrode of the electrode body, and the other is electrically connected to the negative electrode of the electrode body. The electrode terminals 120 are formed from a conductive material such as aluminum, aluminum alloy, copper, or copper alloy.

[0031] In the energy storage device 1 configured in this way, the side wall portion 14 of the outer casing 10 has multiple fins (multiple first fins 51 and multiple second fins 61), thereby improving the heat dissipation efficiency for the heat generated by the energy storage element unit 101. The configuration of the side wall portion 14 and its surroundings, which has multiple first fins 51 and multiple second fins 61, will be described below with reference to Figures 3 to 5A, in addition to Figure 2 described above.

[0032] [2. Structure of the side wall and its surrounding area] Figure 3 is a cross-sectional view showing the structural relationship between the first fin 51 and the second fin 61 and the energy storage element unit 101 according to the embodiment. In Figure 3, a simplified cross-section of a part of the energy storage device 1 in the ZY plane passing through line III-III in Figure 2 is shown, and the cover 11 is not shown. In Figure 3, each of the multiple energy storage elements 100 is shown in a side view rather than a cross-sectional view. Figure 4 is a plan view (viewed from the positive Z-axis direction) showing the structural relationship between the first fin 51 and the second fin 61 and the energy storage element unit 101 according to the embodiment. The white arrows in Figures 3 and 4 represent the airflow along the first fin 51 or the second fin 61. Figure 5A is a diagram showing the relative sizes of the first heat conductive member 50 and the second heat conductive member 60 according to the embodiment. In Figure 5A, a pair of the first heat conductive member 50 and the second heat conductive member 60 located in the negative Y-axis direction in Figure 4 are shown. In Figure 5A, the second heat conduction member 60 is represented by a solid line, and the first heat conduction member 50, located in the positive Y-axis direction of the second heat conduction member 60, is represented by a dashed line. In Figure 5A, the white circles located at the four corners of the first heat conduction member 50 represent fasteners 59, and the black circles located at the four corners of the second heat conduction member 60 represent fasteners 69. Each of the fasteners 59 and 69 is, for example, a screw.

[0033] As shown in Figures 2 and 3 to 5A above, the energy storage device 1 has a plurality of first fins 51 inside the outer casing 10, thereby improving the heat dissipation efficiency for the heat generated by the energy storage element unit 101. Specifically, the energy storage device 1 according to this embodiment comprises an energy storage element unit 101 having one or more energy storage elements 100, and an outer casing 10 that houses the energy storage element unit 101. The energy storage device 1 may have a plurality of energy storage element units 101 inside the outer casing 10. The outer casing 10 has a bottom wall portion 13 facing the energy storage element unit 101 in a first direction (Z-axis direction), and a side wall portion 14 facing the energy storage element unit 101 in a second direction (Y-axis direction) that intersects with the Z-axis direction. The side wall portion 14 has a plurality of first fins 51 on its inner surface 14a facing the energy storage element unit 101, each of which protrudes toward the energy storage element unit 101 and extends along the Z-axis direction.

[0034] In the first direction (Z-axis direction), the energy storage element unit 101 and the bottom wall portion 13 are facing each other, which includes cases where there is a space between the energy storage element unit 101 and the bottom wall portion 13 in the Z-axis direction, where there is no such space, and where some object is placed in the space. In the second direction (Y-axis direction), the energy storage element unit 101 and the side wall portion 14 are facing each other, which includes cases where there is a space between the energy storage element unit 101 and the side wall portion 14 in the Y-axis direction, where there is no such space, and where some object is placed in the space.

[0035] As described above, in the energy storage device 1 according to this embodiment, the side wall portion 14 has a plurality of first fins 51 provided on the inner surface 14a. Therefore, the contact area between the gas (air) inside the outer casing 10 and the side wall portion 14 is increased, and as a result, the amount of heat absorbed by the side wall portion 14 from the heat generated by the energy storage element unit 101 is increased. As a result, the heat generated by the energy storage element unit 101 can be efficiently released (dissipated) to the outside of the outer casing 10 via the side wall portion 14. Generally, the energy storage device 1 is arranged in a position where the bottom wall portion 13 faces downwards, as shown in Figure 2, for example. Therefore, the direction in which the plurality of first fins 51 extend is in the vertical direction, and as a result, the plurality of first fins 51 do not easily resist the flow of hot air moving from bottom to top. In other words, the plurality of first fins 51 are arranged in a position that does not easily obstruct the flow of air whose temperature has risen due to the heat of the energy storage element unit 101. As a result, airflow is more easily generated inside the outer casing 10. In other words, air circulation inside the outer casing 10 is promoted, and as a result, heat from the energy storage element unit 101 can be efficiently transferred to the side wall portion 14 by convection.

[0036] As described above, the energy storage device 1 according to this embodiment can efficiently release the heat generated by the energy storage element unit 101 to the outside. This effect is particularly useful when the outer casing 10 has a structure that seals the inside. For example, in a structure like this embodiment, where a gasket is placed at the joint between the outer casing body 12 and the lid 11 to improve the airtightness of the joint, the exchange of air between the inside and outside of the outer casing 10 under normal conditions is limited. Therefore, it is difficult to immediately replace the air heated inside the outer casing 10 with outside air. In this regard, in this embodiment, a plurality of first fins 51 extending in the vertical direction are provided on the inner surface 14a of the side wall portion 14 of the outer casing 10, thereby promoting the circulation of air inside the outer casing 10. As a result, heat exchange between the air heated inside the outer casing 10 and the outer casing 10, which is at a lower temperature than the air, is promoted. This allows the heat generated by the energy storage element unit 101 to be efficiently released to the outside without relying on the exchange of air between the air inside the outer casing 10 and outside air.

[0037] In this embodiment, when the energy storage device 1 is placed on a horizontal surface, the direction in which the multiple first fins 51 extend is parallel to the vertical direction. That is, as shown in Figures 2 to 5A, when the inner surface of the bottom wall portion 13 (the surface on which the energy storage element unit 101 is placed) is parallel to the XY plane, the direction in which the multiple first fins 51 extend is parallel to the Z axis direction (see, for example, Figure 5A). However, the direction in which the multiple first fins 51 extend does not need to perfectly coincide with the Z axis direction. That is, when a first fin 51 protruding in the Y axis direction is viewed from the Y axis direction, the angle between the direction in which the first fin 51 extends and the Z axis direction does not need to be 0°, and the angle may be greater than 0° and 45° or less. When the angle between the direction in which the first fin 51 extends and the Z axis direction is greater than 0°, the angle is preferably 30° or less, more preferably 20° or less, and even more preferably 10° or less. In other words, when the energy storage device 1 is placed on a surface parallel to the horizontal plane, if the angle between the direction in which the first fin 51 extends and the vertical direction is 45° or less, the first fin 51 can guide hot air upward without accumulating (i.e., promote air circulation) and remove heat from the hot air. Not all of the multiple first fins 51 do not need to satisfy the above angle condition. If one or more of the multiple first fins 51 satisfy the above angle condition, air circulation can be promoted by that one or more first fins 51.

[0038] The side wall portion 14 of the exterior body 10 according to this embodiment has a plurality of first fins 51 that promote the circulation of air inside the exterior body 10, as well as a plurality of second fins 61 that release the heat received by the side wall portion 14 to the outside of the exterior body 10. Specifically, the side wall portion 14 has a plurality of second fins 61 arranged on the outer surface 14b opposite to the inner surface 14a. Each of the plurality of second fins 61 extends in a direction along the outer surface 14b.

[0039] Thus, by having multiple second fins 61 on the outer surface 14b of the side wall portion 14, the contact area with the gas (air) outside the outer body 10 is increased. As a result, the heat absorbed by the inner surface 14a, which has multiple first fins 51, can be efficiently released by the multiple second fins 61 provided on the outer surface 14b.

[0040] More specifically, each of the multiple second fins 61 extends in a third direction (X-axis direction) that intersects the Z-axis and Y-axis directions.

[0041] Generally, the energy storage device 1 is positioned with the bottom wall portion 13 on which the energy storage element unit 101 is placed facing downwards. In this case, the second fins 61 exposed to the outside air of the outer casing 10 are positioned to extend laterally. Therefore, when the energy storage device 1 is mounted on a mobile device, or when the energy storage device 1 is installed in a position where it is exposed to horizontally flowing wind, the side wall portion 14 can be efficiently cooled by the air flowing along the second fins 61. Thus, the heat dissipation efficiency for the heat generated by the energy storage element unit 101 can be further improved.

[0042] In this embodiment, the exterior body 10 is made of a metal such as iron, and therefore the weight of the power storage device 1 is relatively large. For this reason, by placing the power storage device 1 at the rear of the forklift, for example, the power storage device 1 can be used as a power supply for the operation of the forklift and can also be used as at least part of the balance weight (counterweight). In this case, the power storage device 1 is placed on the forklift with the bottom wall portion 13 facing downwards and in a position where the direction in which the multiple second fins 61 extend (the X-axis direction in this embodiment) coincides with the straight-line direction of the forklift. As a result, when the forklift is moving, the airflow around the power storage device 1 is more likely to coincide with the direction in which the multiple second fins 61 extend, and as a result, heat exchange between the multiple second fins 61 and the outside air is performed more efficiently.

[0043] In this embodiment, the multiple first fins 51, which have the heat dissipation function described above, are part of a component manufactured separately from the side wall portion 14. By fixing this component to the inner surface 14a of the side wall portion 14, the side wall portion 14 has multiple first fins 51. The same applies to the multiple second fins 61. In this embodiment, the multiple second fins 61 are part of a component manufactured separately from the side wall portion 14. By fixing this component to the outer surface 14b of the side wall portion 14, the side wall portion 14 has multiple second fins 61.

[0044] Specifically, multiple first fins 51 are provided on a first heat conductive member 50 fixed to the inner surface 14a of the side wall portion 14. Multiple second fins 61 are provided on a second heat conductive member 60 fixed to the outer surface 14b of the side wall portion 14. When viewed from the Y-axis direction, the second heat conductive member 60 is formed to be larger in size than the first heat conductive member 50 (see Figure 5A). In other words, when viewed from the Y-axis direction, the first heat conductive member 50 is positioned within the arrangement range of the second heat conductive member 60.

[0045] With this configuration, the members having multiple fins (first fins or second fins) (first heat conducting member 50 and second heat conducting member 60) can be manufactured separately from the side wall portion 14. Therefore, the exterior body 10 having multiple fins can be manufactured more easily than, for example, when the multiple fins are formed integrally with the side wall portion 14.

[0046] As shown in Figure 5A, the second heat conduction member 60 on the outer surface 14b is larger than the first heat conduction member 50 on the inner surface 14a. Therefore, for example, the second heat conduction member 60 can more reliably receive the heat absorbed by the first heat conduction member 50, and as a result, the heat inside the outer casing 10 can be released to the outside of the outer casing 10 more efficiently. Furthermore, it is also possible to form the second heat conduction member 60 to cover almost the entire area of ​​the outer surface 14b, which has a larger area than the inner surface 14a of the side wall portion 14, thereby further increasing the heat dissipation area by the second heat conduction member 60.

[0047] Because the second heat conduction member 60 is larger than the first heat conduction member 50, it is easy to position, for example, the fasteners for fixing the second heat conduction member 60 and the fasteners for fixing the first heat conduction member 50 to the side wall 14 at offset positions in the direction of the side wall 14's expansion. For example, as shown in Figure 5A, consider a case where the rectangular second heat conduction member 60, when viewed from the Y-axis direction, is fixed to the side wall 14 with fasteners 69 (screws, etc.) placed at each of its four corners. In this case, the rectangular first heat conduction member 50, when viewed from the Y-axis direction, can also be similarly fixed to the side wall 14 with fasteners 59 (screws, etc.) placed at each of its four corners. In other words, the fasteners 59 placed at the four corners of the rectangular first heat conduction member 50 and the fasteners 69 placed at the four corners of the rectangular second heat conduction member 60 can be positioned so as not to interfere with each other. Therefore, the screw holes into which the fastener 59 is screwed and the screw holes into which the fastener 69 is screwed can be formed relatively deep (for example, more than half the thickness of the side wall portion 14). This allows the first heat conductive member 50 and the second heat conductive member 60 to be stably fixed to the side wall portion 14.

[0048] In this embodiment, as shown in Figures 2 and 4, for example, the length of each of the multiple first fins 51 in the direction of protrusion of the first fin 51 (Y-axis direction) is greater than or equal to the width T1 of the first fin 51 in the X-axis direction (i.e., the thickness of the first fin 51).

[0049] Thus, since the first fin 51 has a relatively thin shape in terms of thickness (width in the X-axis direction), a relatively large number of first fins 51 can be arranged in the X-axis direction. This contributes to improved heat dissipation efficiency. In this embodiment, similar to the first fin 51, the length of the second fin 61 in the protruding direction is greater than or equal to the thickness of the second fin 61 (T2, see Figure 3). Therefore, a relatively large number of second fins 61 can be arranged in the X-axis direction. This contributes to improved heat dissipation efficiency.

[0050] In this embodiment, as shown in Figures 2 to 4, for example, in the energy storage element unit 101, each of the multiple energy storage elements 100 is a rectangular battery and is arranged in the Y-axis direction with its long side surface 110a facing the Y-axis direction.

[0051] The long side 110a of the rectangular battery-shaped energy storage element 100 is the side with the largest surface area, and therefore dissipates a large amount of heat. Accordingly, by arranging multiple first fins 51 at positions facing the long side 110a of the energy storage element 100 at the Y-axis end of the energy storage element unit 101, more efficient heat dissipation is achieved.

[0052] In this embodiment, as shown in Figures 3 and 4, for example, the electrical element unit 101 is positioned to form a gap between itself and the plurality of first fins 51.

[0053] Thus, because a gap exists between the multiple first fins 51 and the energy storage element unit 101, the air heated by the energy storage element unit 101 can freely circulate through this gap. In other words, for example, air stagnation in the direction in which the multiple first fins 51 are aligned becomes less likely. This contributes to improving the heat dissipation efficiency of the energy storage device 1.

[0054] In this embodiment, as shown in Figure 3 for example, each of the multiple first fins 51 extends along the Z-axis direction on the inner surface 14a of the side wall portion 14, but not to the edges on one and the other sides of the inner surface 14a in the Z-axis direction.

[0055] Thus, in this embodiment, there is space in the Z-axis positive and Z-axis negative directions of the multiple first fins 51 that allows air to flow freely. Therefore, for example, a situation in which air moving from bottom to top along the first fins 51 becomes stagnant near the upper end of the first fins 51 becomes less likely. Furthermore, for example, a situation in which airflow attempting to move in the X-axis direction is obstructed by the lower end of the first fins 51 becomes less likely. These factors contribute to improving the heat dissipation efficiency of the energy storage device 1.

[0056] More specifically, the first heat conductive member 50 has a flat plate-shaped first base 55 and a plurality of first fins 51 arranged on one surface of the first base 55 in the thickness direction. The first heat conductive member 50 is fixed to the side wall 14 such that the other surface of the first base 55 in the thickness direction is in surface contact with the side wall 14. Therefore, it can be said that the plurality of first fins 51 of the side wall 14 are arranged on the inner surface 14a via the first base 55. Alternatively, it can be said that the side of the first base 55 facing the energy storage element unit 101 constitutes a part of the inner surface 14a of the side wall 14. In this case, it can be said that the plurality of first fins 51 of the side wall 14 are arranged on the inner surface 14a. The second heat conductive member 60 is similar to the first heat conductive member 50, and has a flat plate-shaped second base 65 and a plurality of second fins 61 arranged on one surface of the second base 65 in the thickness direction. The second heat conductive member 60 is fixed to the side wall portion 14 such that the other surface of the second base 65 in the thickness direction is in surface contact with the side wall portion 14. Therefore, it can be said that the multiple second fins 61 of the side wall portion 14 are arranged on the outer surface 14b via the second base 65. Alternatively, it can be said that the side of the second base 65 opposite to the side wall portion 14 constitutes a part of the outer surface 14b of the side wall portion 14. In this case, it can be said that the multiple second fins 61 of the side wall portion 14 are arranged on the outer surface 14b.

[0057] Each of the first heat conduction member 50 and the second heat conduction member 60 is formed of a metal such as iron, aluminum, or an aluminum alloy, similar to the outer casing 10. In this case, the first heat conduction member 50, which has a first base 55 and a plurality of first fins 51, is manufactured by various methods such as extrusion, casting, machining, or welding, or a combination thereof. The same applies to the second heat conduction member 60.

[0058] The manufacturing methods for the first heat conduction member 50 and the second heat conduction member 60 are not limited to these. For example, a first heat conduction member having multiple first fins 51 may be formed by bending a single metal plate along multiple bending lines aligned in the X-axis direction and parallel to the Z-axis direction. Figure 5B is a plan view showing a first heat conduction member 50a formed from a single metal plate 80. In the first heat conduction member 50a shown in Figure 5B, the collection of portions (partial bases 55a) that form a surface parallel to the XZ plane corresponds to the first base 55. In this case, the first fins 51 are formed from two layers of metal plates (partial fins 52) that overlap in the X-axis direction. Therefore, the space between the two layers of partial fins 52 can also be used as an air passage. The same applies to the second heat conduction member 60.

[0059] The materials forming the first heat conductive member 50 and the second heat conductive member 60 do not have to be metal. For example, the first heat conductive member 50 and the second heat conductive member 60 may be formed from resin such as PC, or a mixed material in which a heat conductive filler is mixed with resin.

[0060] The above description of the energy storage device 1 according to the embodiment focuses on the configuration of the side wall portion 14 having a plurality of first fins 51 and a plurality of second fins 61, and its surrounding area. However, the configuration of the side wall portion 14 and its surrounding area may differ from that shown in Figures 2 to 5A. Therefore, the following describes modified configurations of the side wall portion 14 and its surrounding area, focusing on the differences from the above embodiment.

[0061] [3-1. Variation 1] Figure 6 is a cross-sectional view showing the structural relationship between the first fin 51a and the second fin 61a and the energy storage element unit 101 according to Modification 1 of the embodiment. The position of the cross-section in Figure 6 corresponds to the position of the cross-section in Figure 3. In Figure 6, a simplified cross-section of the end of the energy storage device 1a in the negative Y-axis direction according to Modification 1 is shown, and the cover 11 is not shown. In Figure 6, of the multiple first fins 51a arranged in the X-axis direction, only the first fin 51a at the position of the cross-section (the first fin 51a in the foreground) is shown in a shaded area. The multiple first fins 51a behind the first fin 51a in the foreground are hidden by the first fin 51a and cannot be seen. Therefore, in Figure 6, the existence of the multiple first fins 51a in the background is schematically represented by dashed lines. These supplementary points regarding Figure 6 also apply to Figures 7 and 8, which will be described later.

[0062] In the modified energy storage device 1a, the side wall portion 14 of the outer body 12 of the outer body 10a has a plurality of first fins 51a on the inner surface 14a facing the energy storage element unit 101, each protruding toward the energy storage element unit 101 and extending along the Z-axis direction. The side wall portion 14 further has a plurality of second fins 61a arranged on the outer surface 14b opposite to the inner surface 14a. Each of the plurality of second fins 61a extends in a direction along the outer surface 14b. Specifically, each of the plurality of second fins 61a extends in the X-axis direction. These features are common to the plurality of first fins 51 and plurality of second fins 61 in the embodiment.

[0063] In this modified example, each of the multiple first fins 51a and the multiple second fins 61a is integrally provided on the side wall portion 14, which differs from the multiple first fins 51 and the multiple second fins 61 in the embodiment. In this case, each of the multiple first fins 51a and the multiple second fins 61a is directly connected to the side wall portion 14, so that heat exchange with the side wall portion 14 can be carried out more efficiently.

[0064] If metal is used as the material for the exterior body 10a according to this modified example, the plurality of first fins 51a and plurality of second fins 61a integrally provided on the side wall portion 14 may be formed by, for example, casting, machining, welding, or a combination thereof. If resin is used as the material for the exterior body 10a, the side wall portion 14 having the plurality of first fins 51a and plurality of second fins 61a may be manufactured by injection molding using a combination of a plurality of molds.

[0065] Only one of the multiple first fins 51a and the multiple second fins 61a may be integrally provided on the side wall portion 14. For example, only the multiple first fins 51a may be integrally provided on the side wall portion 14. In this case, by fixing the second heat conductive member 60 (Figures 2 to 4) to the side wall portion 14, the side wall portion 14 can also be provided with multiple second fins 61.

[0066] [3-2. Variation 2] Figure 7 is a cross-sectional view showing the structural relationship between the first fin 51b and the second fin 61b and the energy storage element unit 101 according to Modification 2 of the embodiment. Figure 8 is a cross-sectional view showing the heat conductive member 70 according to Modification 2 of the embodiment separated from the outer casing 10b.

[0067] In the modified energy storage device 1b, the side wall portion 14 of the outer body 12 of the outer body 10b has a plurality of first fins 51b on its inner surface 14a facing the energy storage element unit 101, each protruding toward the energy storage element unit 101 and extending along the Z-axis direction. The side wall portion 14 further has a plurality of second fins 61b arranged on the outer surface 14b opposite to the inner surface 14a. Each of the plurality of second fins 61b extends in a direction along the outer surface 14b. Specifically, each of the plurality of second fins 61b extends in the X-axis direction. These features are common to the plurality of first fins 51 and plurality of second fins 61 in the embodiment.

[0068] In the modified energy storage device 1b, a heat conductive member 70 having a plurality of first fins 51b and a plurality of second fins 61b integrally is arranged in a side wall opening 14e provided in the side wall portion 14. In this respect, the plurality of first fins 51b and a plurality of second fins 61b in this modified example differ from the plurality of first fins 51 and a plurality of second fins 61 in the embodiment.

[0069] In other words, in the outer casing 10b, a side wall opening 14e is pre-formed in the side wall portion 14, penetrating in the thickness direction (Y-axis direction), and the heat conductive member 70 is inserted into the side wall opening 14e and fixed to the peripheral edge of the side wall opening 14e by welding or the like. This forms a side wall portion 14 having a plurality of first fins 51b and a plurality of second fins 61b.

[0070] Specifically, the heat conductive member 70 has a base body 75 that closes the side wall opening 14e when inserted into the side wall opening 14e of the side wall portion 14, and a plurality of first fins 51b and a plurality of second fins 61b provided on the base body 75. The plurality of first fins 51b are provided on the inner surface 75a of the base body 75 that faces the energy storage element unit 101. The plurality of second fins 61b are provided on the outer surface 75b of the base body opposite to the energy storage element unit 101. In this modified example, as shown in Figures 7 and 8, the inner surface 14a of the side wall portion 14 is formed by the inner surface 75a of the base body and the inner surface 14c of the opening periphery of the side wall portion 14. Furthermore, the outer surface 14b of the side wall portion 14 is formed by the outer surface 75b of the base body and the outer surface 14d of the opening periphery of the side wall portion 14. In this configuration, the base body 75 is a member that forms part of the side wall portion 14, as shown in Figure 7. Therefore, it can also be described that each of the multiple first fins 51b and the multiple second fins 61b is integrally provided with the side wall portion 14.

[0071] The heat-conducting member 70 configured as described above is manufactured, for example, by various methods such as extrusion, casting, cutting, or welding of a metal material such as iron, or a combination thereof.

[0072] With this configuration, similar to the energy storage device 1b in the modified example 1, each of the multiple first fins 51b and the multiple second fins 61b is directly connected to the side wall portion 14, so that heat exchange with the side wall portion 14 can be carried out more efficiently.

[0073] Even if a resin such as PC is used instead of metal as the material for forming the exterior body 10b in this modified example, the portion having multiple first fins 51b and multiple second fins 61b (i.e., the heat conducting member 70) can be formed from a metal with high thermal conductivity. As a result, the heat generated by the energy storage element unit 101 can be released to the outside of the exterior body 10 more efficiently compared to the case where the entire exterior body 10b is formed from resin.

[0074] In this modified example, the heat conduction member 70, which has a plurality of first fins 51b and a plurality of second fins 61b, can be manufactured as a separate component from the outer casing 10b. Therefore, forming the two types of fins (first fins 51b and second fins 61b) that extend in directions that intersect each other is easier than when the two types of fins are integrally provided on the outer casing 10b (see, for example, Modified Example 1).

[0075] The heat conduction member 70 may have only one of the plurality of first fins 51b and the plurality of second fins 61b. For example, only the plurality of first fins 51b may be integrally provided on the base body 75. In this case, by fixing the second heat conduction member 60 (Figures 2 to 4) to the outer surface 75b of the base body 75 which is fixed to the outer casing 10b, the side wall portion 14 can also be provided with a plurality of second fins 61.

[0076] The method of joining the heat conduction member 70 to the peripheral edge of the side wall opening 14e is not limited to welding. The joining method may include heat welding (when at least one of the heat conduction member 70 and the outer casing 10b is made of resin), adhesive bonding, or fixing with screws. For example, a flange may be provided on the outer circumference of the base body 75, and the flange and the peripheral edge of the side wall opening 14e may be joined with multiple screws.

[0077] [4. Other variations] Although the embodiment of the energy storage device 1 and its modified forms have been described above, the present invention is not limited to the embodiment and its modified forms. In other words, the embodiments disclosed herein are illustrative and not restrictive in all respects, and the scope of the present invention includes all modifications in the sense and scope equivalent to the claims.

[0078] The shape, number, and arrangement layout of each of the multiple first fins 51 on the outer casing 10 do not have to be those shown in Figures 2 to 5A. For example, the first fins 51 may be trapezoidal or triangular in shape, with their thickness (width in the X-axis direction) decreasing as they move away from the side wall 14 when viewed from the Z-axis direction. The height of the first fins 51 from the side wall 14 does not need to be constant in the Z-axis direction. For example, the height of the first fins 51 from the side wall 14 may be made lower as they approach the upper end of the first fin 51. In any case, each of the multiple first fins 51 extends along the Z-axis direction, allowing them to efficiently remove heat from the air moving from one side to the other in the Z-axis direction.

[0079] The same applies to the multiple second fins 61; the shape, number, and arrangement layout of each of the multiple second fins 61 do not have to be those shown in Figures 2 to 5A. For example, the direction in which each of the multiple second fins 61 extends when viewed from the Y-axis direction does not need to be parallel to the X-axis direction (see, for example, Figure 5A). In other words, the multiple second fins 61 only need to release the heat received through the side wall portion 14 to the outside. Therefore, the direction in which the multiple second fins 61 extend should be along the outer surface 14b of the side wall portion 14. For example, if the energy storage device 1 is placed in an environment where outside air flows in the vertical direction, the direction in which each of the multiple second fins 61 extends may be parallel to the vertical direction (Z-axis direction). This allows for more efficient heat exchange between the outside air and the multiple second fins 61.

[0080] It is not essential that the outer casing 10 has multiple second fins 61. For example, if the outer casing 10 is made of a metal such as iron, the multiple first fins 51 can also release heat received from the air inside the outer casing 10 to the outside of the outer casing 10 through the surface of the outer casing 10 (including the outer surface 14b of the side wall portion 14).

[0081] Each of the multiple first fins 51 does not have to be formed in a perfectly straight line when viewed from the protruding direction (Y-axis direction). For example, a part of the first fin 51 may be curved or bent when viewed from the Y-axis direction. In other words, each of the multiple first fins 51 may have a distortion that does not substantially obstruct the airflow as long as it extends along the Z-axis direction. The same applies to the multiple second fins 61. In other words, if the outer casing 10 has multiple second fins 61, each of the multiple second fins 61 may have a distortion that does not substantially obstruct the airflow as long as it extends in a direction along the outer surface 14b of the side wall portion 14.

[0082] The first heat conductive member 50 has a structure in which a plurality of first fins 51 are arranged in the X-axis direction on a single first base body 55 (see Figure 4). However, one first base body may be provided corresponding to each of the plurality of first fins 51. In other words, when viewed from the Z-axis direction, each of the plurality of first fins 51 may be formed in a T-shape. Furthermore, one first base body may be provided for every two or more first fins 51. In other words, the first heat conductive member 50 according to the embodiment may be configured as an assembly of a plurality of members separated for each of the one or more first fins 51. In any case, each group containing one or more first fins 51 can be arranged on the inner surface 14a of the side wall portion 14 independently of the other groups. Therefore, the degree of freedom in the arrangement layout of the plurality of first fins 51 is improved.

[0083] Various supplementary details regarding the plurality of first fins 51 and plurality of second fins 61 according to the above embodiment may also be applied to the plurality of first fins 51a and plurality of second fins 61a according to Modification 1 above, and to the plurality of first fins 51b and plurality of second fins 61b according to Modification 2 above. Configurations constructed by arbitrarily combining the components included in the above embodiment and its modifications are also within the scope of the present invention. [Industrial applicability]

[0084] This invention can be applied to energy storage devices equipped with energy storage elements such as lithium-ion secondary batteries. [Explanation of Symbols]

[0085] 1, 1a, 1b Energy storage device 10, 10a, 10b Outer casing 13 Bottom wall section 14 Side wall section 14a Inner surface 14b External surface 14c Inner surface of the opening periphery 14d Outer surface of the opening periphery 14e Side wall opening 50, 50a First heat conduction member 51, 51a, 51b First fin 52 partial fins 55 First base 55a Partial base 59, 69 Fixtures 60 Second heat conduction member 61, 61a, 61b Second fin 65 Second base 70 Heat conductive material 75 Base 75a Base inner surface 75b Base body outer surface 80 metal plate 100 energy storage elements 101 Energy Storage Element Unit 110a long side

Claims

1. A storage element unit having one or more energy storage elements, The system comprises an outer casing that houses the energy storage element unit, The exterior body is, It has a bottom wall portion facing the energy storage element unit in a first direction, and a side wall portion facing the energy storage element unit in a second direction intersecting the first direction, The side wall portion has a plurality of first fins on its inner surface facing the energy storage element unit, each of which protrudes toward the energy storage element unit and extends along the first direction. Energy storage device.

2. The side wall portion further comprises a plurality of second fins arranged on the outer surface opposite to the inner surface, each having a plurality of second fins extending in a direction along the outer surface. The energy storage device according to claim 1.

3. Each of the plurality of second fins extends in a third direction intersecting the first direction and the second direction. The energy storage device according to claim 2.

4. The plurality of first fins are provided on a first heat conductive member fixed to the inner surface of the side wall portion, The plurality of second fins are provided on a second heat conductive member fixed to the outer surface of the side wall portion, When viewed from the second direction, the second heat conduction member is formed to be larger in size than the first heat conduction member. The energy storage device according to claim 2 or 3.

Images