Energy storage device

Abstract

In the energy storage device, the goal is to achieve both miniaturization and rapid drainage from the pack case, while simultaneously preventing water from entering the pack case. [Solution] The energy storage device comprises a valve case housed in the internal space of a pack case containing energy storage cells, a valve member fitted inside the valve case, and a breathable membrane member provided on the lower surface of the pack case to close the opening. The valve case has a hole communicating with the opening and a first inclined surface whose diameter decreases as it approaches the internal space. The valve member has a second inclined surface opposite the first inclined surface. The device can achieve a first state in which a communication path is formed that connects the outside and the internal space of the pack case through the gap between the first and second inclined surfaces, and a second state in which the first and second inclined surfaces come into contact with each other as the valve member moves in a first direction from the outside to the internal space of the pack case, thereby blocking the communication path. A groove or hole included in the communication path is formed in a part of the circumferential direction of the second inclined surface.

Description

Technical Field

[0001] This technology relates to a power storage device.

Background Art

[0002] Examples of technologies that disclose a drainage structure from a pack case of a battery pack include those described in JP-A-2020-113488 (Patent Document 1), JP-A-2011-173447 (Patent Document 2), and JP-A-2019-220342 (Patent Document 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, when water leakage or the like occurs inside the pack case of a power storage device, prompt drainage is required. On the other hand, it is also required to suppress water intrusion from outside the pack case. From a different perspective, miniaturization of the power storage device is required. From the viewpoint of achieving both of these points, there is still room for improvement in the conventional drainage structure.

[0005] An object of this technology is to provide a power storage device that achieves both prompt drainage from the pack case and suppression of water intrusion into the pack case while achieving miniaturization.

Means for Solving the Problems

[0006] This technology provides the following power storage device.

[0007] [1] A pack case comprising an internal space for housing energy storage cells, a lower surface defining the internal space, and an opening provided on the lower surface; a valve case attached to the lower surface of the pack case adjacent to the opening and housed in the internal space; a valve member fitted inside the valve case; and a breathable membrane member provided on the lower surface of the pack case to close the opening, wherein the valve case has a hole communicating with the opening and a first inclined surface that reduces the diameter of the hole towards the internal space side, and the valve The member has a second inclined surface facing the first inclined surface, and is capable of achieving a first state in which a communication path is formed that connects the outside of the pack case and the internal space through the gap between the first inclined surface and the second inclined surface, and a second state in which the first inclined surface and the second inclined surface come into contact as the valve member moves in a first direction from the outside of the pack case toward the internal space, thereby blocking the communication path, wherein a groove or hole included in the communication path is formed in a part of the circumferential direction of the second inclined surface.

[0008] [2] The energy storage device according to [1], wherein the first direction is the direction perpendicular to the lower surface.

[0009] [3] The energy storage device according to [1] or [2], wherein the valve member includes a first portion adjacent to the outside of the pack case with respect to the second inclined surface and a second portion adjacent to the outside of the pack case with respect to the first portion and having a smaller diameter than the first portion.

[0010] [4] The energy storage device according to [3], wherein the valve case includes a guide portion that protrudes from the inner circumferential surface of the hole toward the second portion of the valve member and guides the movement of the valve member in the first direction.

[0011] [5] The energy storage device according to any one of [1] to [4], wherein the membrane member is made of a water-soluble material.

[0012] [6] The energy storage device according to any one of [1] to [5], wherein the pack case includes a gas discharge valve that opens when the pressure in the internal space rises, and the gas discharge valve is configured to open at a pressure lower than the pressure at which the membrane member ruptures or falls off the lower surface. [Effects of the Invention]

[0013] This technology makes it possible to achieve both miniaturization of the energy storage device and rapid drainage from the pack case, as well as suppression of water ingress into the pack case. [Brief explanation of the drawing]

[0014] [Figure 1] This is a top view of the energy storage device. [Figure 2] This is a perspective view of the valve component. [Figure 3] This is a cross-sectional perspective view of the valve case. [Figure 4] This figure shows the AA cross-section in Figure 1 in the first state (valve open state). [Figure 5] This figure shows the AA cross-section in Figure 1 in the second state (valve open state). [Figure 6] This figure shows the BB cross section in Figure 1 in the first state (valve open state). [Figure 7] This figure shows the BB cross section in Figure 1 in the second state (valve open state). [Modes for carrying out the invention]

[0015] Embodiments of this technology are described below. Note that the same or corresponding parts may be denoted by the same reference numerals, and their descriptions may not be repeated.

[0016] In the embodiments described below, when referring to the number, quantity, etc., unless otherwise specified, the scope of the present technology is not necessarily limited to such number, quantity, etc. Also, in the following embodiments, each component is not necessarily essential for the present technology, unless otherwise specified. Further, the present technology is not limited to necessarily achieving all the effects mentioned in the present embodiments.

[0017] In this specification, the descriptions of "comprise", "include", and "have" are in an open - ended form. That is, when including a certain configuration, other configurations other than the said configuration may or may not be included.

[0018] Also, in this specification, when geometric terms and terms representing positional and directional relationships, such as "parallel", "orthogonal", "diagonal 45°", "coaxial", "along", etc., are used, these terms allow for manufacturing errors or slight variations. When terms representing relative positional relationships such as "upper side", "lower side", etc., are used in this specification, these terms are used to indicate the relative positional relationship in one state, and depending on the installation direction of each mechanism (for example, turning the entire mechanism upside down, etc.), the relative positional relationship can be reversed or rotated at an arbitrary angle.

[0019] Also, in this specification, the dimensions such as the width, length, diameter, etc. of each member shown in the figures are not limited to those shown in the figures and can be appropriately changed. In this specification, each configuration may be assigned ordinal numbers such as "first", "second", etc., but these ordinal numbers do not limit the priority, order, etc., unless explicitly specified.

[0020] In this specification, the "power storage device" or "power storage cell" is not limited to a "battery", "battery pack" or "battery cell", and may include a capacitor, etc. In this specification, the "battery" is not limited to a lithium - ion battery and may include other batteries such as nickel - hydrogen batteries and sodium - ion batteries.

[0021] In this specification, "battery cell" is not necessarily limited to prismatic cells, but may also include cells of other shapes such as cylindrical, pouch-type, and blade-type cells. Furthermore, "batteries" or "battery cells" can be installed in hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs). However, the use of "batteries" or "battery cells" is not limited to automotive applications.

[0022] Figure 1 is a top view of the battery pack 1 (energy storage device). As shown in Figure 1, the battery pack 1 includes a pack case 100, battery cells 200 (energy storage cells), a separator 300, a valve device 400, a gas discharge valve 500, and a cooler 600.

[0023] The pack case 100 has an internal space 100A. The internal space 100A houses the battery cells 200 and separators 300. The battery cells 200 and separators 300 are arranged alternately along the Y-axis. The separators 300 are insulating members provided between a plurality of battery cells 200.

[0024] The valve device 400 (first valve device) is provided on the lower surface of the pack case 100. The lower surface of the pack case 100 is located vertically downward when the battery pack 1 is mounted on the vehicle. The lower surface of the pack case 100 extends in a direction perpendicular to the Z-axis direction.

[0025] The gas discharge valve 500 (second valve device) is provided on the pack case 100 at a different location from the valve device 400. Preferably, the gas discharge valve 500 is provided on a different surface of the pack case 100 from the surface on which the valve device 400 is provided. In the example in Figure 1, the valve device 400 is provided on the lower surface of the pack case 100, and the gas discharge valve 500 is provided on the side surface of the pack case 100.

[0026] The gas discharge valve 500 opens when the pressure in the internal space 100A rises, preventing the pressure in the internal space 100A from rising excessively. This ensures reliable protection of the pack case 100 (prevention of damage, etc.). The gas discharge valve 500 is configured to open at a pressure (second pressure) lower than the pressure (first pressure) at which the membrane member 30, described later, ruptures or falls off the bottom surface of the pack case 100. Therefore, when the internal pressure in the internal space 100A rises, the gas discharge valve 500 is reliably activated, preventing gas from being discharged from unintended locations.

[0027] The cooler 600 is housed in the internal space 100A of the pack case 100. A cooling medium for cooling the battery cells 200 can be circulated through the cooler 600. By housing the cooler 600 in the internal space 100A, the battery cells 200 can be cooled efficiently. Furthermore, by providing a valve device 400 on the bottom surface of the pack case 100, even if the cooling medium (cooling liquid) from the cooler 600 leaks into the internal space 100A, it can be quickly drained to protect the battery cells 200 (preventing short circuits, etc.).

[0028] Figures 2 and 3 show the valve member 10 (Figure 2) and valve case 20 (Figure 3) that constitute the valve device 400, respectively. The valve member 10 and valve case 20 can be made of materials such as resin or metal.

[0029] As shown in Figure 2, the valve member 10 includes a valve body 11, an inclined surface 12 (second inclined surface), a shaft 13, and a drainage groove 14 (groove). The valve member 10 is fitted inside the valve case 20.

[0030] The valve body portion 11 (first portion) is adjacent to the outside of the pack case 100 with respect to the inclined surface 12. The shaft portion 13 (second portion) is adjacent to the outside of the pack case 100 with respect to the valve body portion 11. The shaft portion 13 is formed to have a smaller diameter than the valve body portion 11.

[0031] The drainage channel 14 is formed in a part of the circumferential direction of the inclined surface 12. When the valve device 400 is in the open state, the drainage channel 14 constitutes part of the passage (communication path) that connects the outside and the internal space 100A of the pack case 100. Instead of the drainage channel 14, a hole that penetrates the valve body 11 may be provided in a part of the circumferential direction of the inclined surface 12.

[0032] As shown in Figure 3, the valve case 20 includes a cylindrical hole 21 (hole portion), an inclined surface 22 (first inclined surface), a drainage groove 23, a guide portion 24, and an opening 25.

[0033] The inclined surface 22 and the opening 25 are provided at one end (upper end) of the cylindrical hole 21. The drainage groove 23 and the guide portion 24 are provided at the other end (lower end) of the cylindrical hole 21. The drainage groove 23 and the guide portion 24 are formed alternately so as to be adjacent to each other in the circumferential direction of the cylindrical hole 21. The guide portion 24 is formed so as to protrude inward from the inner circumferential surface of the cylindrical hole 21 toward the shaft portion 13 of the valve member 10 in a part of the circumferential direction of the cylindrical hole 21.

[0034] The valve body portion 11 of the valve member 10 fits into the cylindrical hole 21 of the valve case 20. The inclined surface 12 of the valve member 10 faces the inclined surface 22 of the valve case 20. When the inclined surfaces 12 and 22 are separated, the valve device 400 opens, and when the inclined surfaces 12 and 22 come into contact with each other, the valve device 400 closes. The shaft portion 13 of the valve member 10 fits into the guide portion 24 of the valve case 20. When the valve member 10 moves up and down relative to the valve case 20, the shaft portion 13 is guided by the guide portion 24.

[0035] Figures 4 and 5 show the AA cross-section in Figure 1. Figures 6 and 7 show the BB cross-section in Figure 1. Figures 4 and 6 show the valve device 400 in the open state (first state), and Figures 5 and 7 show the valve device 400 in the open state (second state).

[0036] As shown in Figures 4 to 7, the valve case 20 of the valve device 400 is mounted inside the lower surface 100B of the pack case 100. The lower surface 100B of the pack case 100 defines the internal space 100A. Therefore, the valve case 20 is housed in the internal space 100A of the pack case 100. By integrating the valve case 20 into the pack case 100, the battery pack 1 can be miniaturized.

[0037] An opening 100C is provided on the lower surface 100B of the pack case 100. The valve case 20 is positioned adjacent to the opening 100C. The cylindrical hole 21 of the valve case 20 communicates with the opening 100C of the pack case 100. The inclined surface 22 is inclined in a direction that reduces the inner diameter of the cylindrical hole 21 as it moves towards the upper side in the figure, i.e., towards the inside of the pack case 100 (towards the internal space 100A). The inclined surface 22 does not necessarily have to be a straight tapered surface, but may have a curved tapered shape. An opening 25 is provided on the inner circumference side of the inclined surface 22.

[0038] A membrane member 30 is provided on the lower surface 100B of the pack case 100 so as to close the opening 100C. By providing the membrane member 30, the intrusion of foreign matter from the outside can be suppressed under normal circumstances.

[0039] The membrane member 30 is breathable. The membrane member 30 can be joined to the bottom surface 100B of the pack case 100 using an adhesive. The membrane member 30 can be made of, for example, a porous material. Preferably, at least one of the membrane member 30 and the adhesive is made of a water-soluble material. The membrane member 30 can be joined to the bottom surface 100B of the pack case 100 using an adhesive made from a highly hydrophilic component such as polyvinyl alcohol.

[0040] As shown in Figures 4 and 6, under normal conditions, the valve device 400 is in the open state (first state). At this time, the valve member 10 falls downward due to gravity and is supported by the valve case 20 from below. Preferably, the shaft portion 13 of the valve member 10 protrudes outward from the inner surface of the lower surface 100B, and the lower end of the shaft portion 13 is on the inner circumference of the opening 100C.

[0041] In this state, a passage (dashed arrow in Figure 4) is formed that connects the outside of the pack case 100 to the internal space 100A through the gap between the inclined surfaces 12 and 22. The outside of the pack case 100 and the internal space 100A are connected via the membrane member 30.

[0042] The communication between the outside of the pack case 100 and the internal space 100A ensures airflow between the internal space 100A and the outside of the pack case 100 under normal conditions. Furthermore, if a leak occurs in the cooler 600 within the internal space 100A, the leaked coolant can be quickly discharged to the outside of the pack case 100 via the valve device 400, protecting the battery cells 200 (preventing short circuits, etc.). At this time, the membrane member 30 will either rupture or dissolve due to the coolant, or detach from the bottom surface 100B of the pack case 100. This ensures a drainage passage for the liquid from the internal space 100A.

[0043] As shown in Figures 5 and 7, when the battery pack 1 is submerged in water, the valve device 400 is in a closed state (second state). At this time, the valve member 10 rises due to the buoyancy from the water 40, and the inclined surface 12 of the valve member 10 and the inclined surface 22 of the valve case 20 come into close contact.

[0044] In this state, the inclined surfaces 12 and 22 are in contact without any gaps, thus blocking the communication path between the outside and the internal space 100A of the pack case 100. At this time, the membrane member 30 either melts or falls off the bottom surface 100B of the pack case 100.

[0045] By blocking the communication path between the outside and the internal space 100A of the pack case 100, water ingress into the pack case 100 is suppressed when the battery pack 1 is submerged in water, thereby protecting the battery cells 200 (preventing short circuits, etc.).

[0046] Thus, in the battery pack 1 according to this embodiment, under normal circumstances, waterproofing and airtightness are ensured by the membrane member 30, while drainage from the internal space 100A of the pack case 100 can be ensured as needed. Furthermore, when the battery pack 1 is submerged in water, the buoyancy from the water 40 causes the valve member 10 to move toward the internal space 100A (first direction), thereby closing the valve device 400 and suppressing water ingress into the internal space 100A of the pack case 100. In this embodiment, the valve member 10 is moved along the Z-axis direction, but the direction of movement of the valve member 10 may be oblique to the Z-axis direction.

[0047] Furthermore, in the battery pack 1 according to this embodiment, a drainage groove 14 (or hole) that constitutes a communication path between the outside and the internal space 100A of the pack case 100 is formed in a part of the circumferential direction of the inclined surface 12. By doing so, the diameter of the valve body 11 (inclined surface 12) can be increased in the parts where the drainage groove 14 (or hole) is not provided. Compared to the case where a gap is provided between the valve member 10 and the valve case 20 around the entire circumference of the inclined surface 12, the buoyancy acting on the valve member 10 when submerged can be increased, thereby improving the responsiveness of the valve device 400.

[0048] While embodiments of the present technology have been described above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present technology is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0049] 1 Battery pack, 10 Valve member, 11 Valve body, 12 Inclined surface, 13 Shaft, 14 Drainage channel, 20 Valve case, 21 Cylindrical hole, 22 Inclined surface, 23 Drainage channel, 24 Guide part, 25 Opening, 30 Membrane member, 40 Water, 100 Pack case, 100A Internal space, 100B Bottom surface, 100C Opening, 200 Battery cell, 300 Separator, 400 Valve device, 500 Gas discharge valve, 600 Cooler.

Claims

1. A pack case including an internal space for housing energy storage cells, a lower surface defining the internal space, and an opening provided on the lower surface, A valve case is attached to the lower surface of the pack case so as to be adjacent to the opening and housed in the internal space, A valve member fitted inside the valve case, The pack case comprises a breathable membrane member provided on the lower surface of the pack case so as to close the opening, The valve case has a hole that communicates with the opening and a first inclined surface that reduces the diameter of the hole as it approaches the internal space. The valve member has a second inclined surface facing the first inclined surface, It is possible to achieve a first state in which a communication path is formed that connects the outside of the pack case and the internal space through the gap between the first inclined surface and the second inclined surface, and a second state in which the valve member moves in a first direction from the outside of the pack case toward the internal space, causing the first inclined surface and the second inclined surface to come into contact and the communication path to be blocked. A power storage device in which a groove or hole included in the communication path is formed in a part of the circumferential direction of the second inclined surface.

2. The energy storage device according to claim 1, wherein the first direction is a direction perpendicular to the lower surface.

3. The energy storage device according to claim 1 or claim 2, wherein the valve member includes a first portion adjacent to the outside of the pack case with respect to the second inclined surface, and a second portion adjacent to the outside of the pack case with respect to the first portion and having a smaller diameter than the first portion.

4. The energy storage device according to claim 3, wherein the valve case includes a guide portion that protrudes from the inner circumferential surface of the hole toward the second portion of the valve member and guides the movement of the valve member in the first direction.

5. The energy storage device according to claim 1 or claim 2, wherein the membrane member is made of a water-soluble material.

6. The energy storage device according to claim 1 or 2, wherein the pack case includes a gas discharge valve that opens when the pressure in the internal space rises, and the gas discharge valve is configured to open at a pressure lower than the pressure at which the membrane member ruptures or falls off the lower surface.

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