Pack Case

Abstract

The disclosed pack case includes a pack housing and a lid that covers the open top surface of the pack housing, and a restraining device that secures the lid to the pack housing has a built-in venting mechanism that releases pressure inside the pack that exceeds a predetermined value to the outside.

Description

[Technical Field]

[0001] The present invention relates to a pack case that can maintain the sealed structure of a lid that is constrained to a pack housing for a longer period of time in the event of thermal runaway.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0114714, filed on August 30, 2023, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference. [Background technology]

[0003] Unlike primary batteries, secondary batteries are rechargeable and have the potential to be small and have large capacities, which has led to extensive research and development in recent years. Demand for secondary batteries as an energy source is rapidly increasing due to the increasing technological development and demand for mobile devices, as well as the emergence of electric vehicles and energy storage systems in response to modern demands for environmental protection.

[0004] Secondary batteries are classified into coin-type batteries, cylindrical batteries, prismatic batteries, and pouch-type batteries depending on the shape of the battery case. The electrode assembly installed inside the battery case of a secondary battery is a power generating element that can be charged and discharged and has a laminated structure of electrodes and a separator.

[0005] Since secondary batteries are required to be used continuously for a long period of time, it is necessary to effectively control the heat generated during the charging and discharging process.If secondary batteries are not cooled smoothly, a positive feedback chain reaction will occur in which a rise in temperature causes an increase in current, and the increase in current causes another rise in temperature, ultimately leading to a catastrophic state of thermal runaway.

[0006] Furthermore, when secondary batteries are grouped together in the form of a module or pack, thermal runaway in one secondary battery can cause other surrounding secondary batteries to continuously overheat, resulting in a thermal propagation phenomenon. In other words, when thermal runaway occurs in a battery module within a battery pack, a large amount of conductive dust, gas, and flames are emitted from the high-voltage terminal of the battery module, causing dust to accumulate at the high-voltage terminals of other adjacent battery modules, and the heat transfer caused by the gas and flames triggers a thermal propagation phenomenon.

[0007] When a heat propagation phenomenon occurs in a battery pack, the pressure and temperature inside the battery pack rise rapidly. To withstand these sudden increases in pressure and temperature, the battery pack must maintain its structural robustness for a considerable period of time. If the battery pack experiences structural collapse and external air flows inside, the combustion reaction will rapidly intensify, posing a significant risk of fire or explosion outside the pack.

[0008] In a structure in which a lid covers and restrains the battery pack housing, there is a limit to the volume increase inside the battery pack, and pressure cannot be released instantly when an event such as heat propagation occurs. This could cause the pack structure to collapse before the venting device is activated, resulting in flames erupting to the outside.

[0009] The prevention and delay of heat propagation is particularly important in electric vehicles, where it can directly affect human life, and related regulations are becoming increasingly strict. This means that a sufficient time delay is required before the battery pack experiences structural collapse, ensuring time for emergency evacuation and safety measures to be taken after a thermal runaway occurs. Therefore, it is necessary to provide a solution that allows the lid, which is constrained to the pack housing, to maintain its sealed structure for a sufficient period of time. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention aims to provide a pack case in which the lid is constrained to the pack housing, and when a thermal runaway or heat propagation event occurs and the internal pressure rises suddenly, the internal pressure can be appropriately released before the lid exceeds its volumetric expansion limit, thereby preventing the pack case from collapsing and ensuring time until the venting device is activated.

[0011] However, the technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0012] The present invention relates to a pack case, which in one example includes a pack housing and a lid that covers the open top surface of the pack housing, and a restraint that secures the lid to the pack housing has a built-in venting mechanism that releases pressure inside the pack that exceeds a predetermined value to the outside.

[0013] In one embodiment of the present invention, the restraint can be fixed to the pack housing by screwing the lid.

[0014] The restraints can be fastened to a center beam and / or cross beams that traverse the interior of the pack housing.

[0015] The restraint device has a pressure inlet that communicates with the space formed by the inner surface of the lid relative to the center beam and / or cross beam, and a pressure outlet that is provided in a head protruding from the outer surface of the lid and communicates with the pressure inlet.

[0016] The lid is fixed to the side frame of the pack case along an edge, and the restraining device can prevent the lid from coming off the pack case.

[0017] The pack housing is provided with at least one venting device, and the venting mechanism built into the restraint can operate at a pressure lower than the operating pressure of the venting device.

[0018] In one embodiment, the venting mechanism may be a valve mechanism that is positioned inside the restraint between the pressure inlet and pressure outlet and is opened and closed by a spring.

[0019] Alternatively, the venting mechanism may be a rupture disk positioned within the restraint between the pressure inlet and pressure outlet.

[0020] The venting mechanism may further include a mesh member installed between the pressure inlet and the rupture disk.

[0021] A capsule containing a liquid fire extinguishing agent may be provided in the space formed between the rupture disk and the mesh member.

[0022] The capsule can burst due to vaporization of the liquid fire extinguishing agent.

[0023] The capsule may burst before the rupture disk.

[0024] For example, the liquid fire extinguishing agent may be a fluorinated ketone. [Effects of the Invention]

[0025] In the pack case according to one embodiment of the present invention, as the internal pressure of the pack increases, the relatively thin lid expands and increases in volume, but before the volume limit is reached and the lid structure collapses, the venting mechanism built into the restraint device releases the pressure, thereby delaying and suppressing the collapse of the lid structure in the event of a thermal runaway or heat propagation event.

[0026] Furthermore, since the venting mechanism built into the restraint is configured to operate before the venting device provided in the pack housing, even in a situation where the internal pressure rises suddenly and the venting device cannot yet operate, the venting mechanism of the restraint operates first, preventing damage to the pack case while ensuring time for the venting device to operate normally.

[0027] However, the technical effects that can be obtained by the present invention are not limited to the effects described above, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0028] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention, and therefore the present invention should not be interpreted as being limited solely to the matters depicted in such drawings. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a view showing a pack case according to an embodiment of the present invention; [Figure 2] FIG. [Figure 3] FIG. 2 is a cross-sectional view taken along line "AA" in FIG. [Figure 4] FIG. 4 is an enlarged cross-sectional view of part "B" in FIG. 3. [Figure 5] 10 is a diagram showing another embodiment of the restraint device. [Figure 6] 6 is a diagram showing a modified embodiment of the restraint device shown in FIG. 5. [Figure 7] 6 is a diagram showing a modified embodiment of the restraint device shown in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0030] Because the present invention can be modified in various ways and can have various embodiments, specific embodiments will be described in detail below.

[0031] However, this is not intended to limit the invention to any particular embodiment, but rather it can be understood to include all modifications, equivalents, or alternatives falling within the spirit and scope of the invention.

[0032] In the present invention, terms such as "comprise" and "have" are intended to specify the presence of features, numbers, steps, operations, components, parts or combinations thereof described in the specification, and can be understood as not precluding the presence or possibility of addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0033] Furthermore, in the present invention, when a layer, film, region, plate, or other portion is described as being "on" another portion, this includes not only the case where it is "directly on" the other portion, but also the case where there is another portion between them. Conversely, when a layer, film, region, plate, or other portion is described as being "under" the other portion, this includes not only the case where it is "directly under" the other portion, but also the case where there is another portion between them. Furthermore, in the present application, being disposed "on" can include not only the case where it is disposed at the top, but also the case where it is disposed at the bottom.

[0034] The present invention relates to a pack case, which in one example includes a pack housing and a lid that covers the open top surface of the pack housing, and a restraint that secures the lid to the pack housing has a built-in venting mechanism that releases pressure inside the pack that exceeds a predetermined value to the outside.

[0035] The pack housing may be provided with at least one venting device, and the venting mechanism built into the restraint may operate at a pressure lower than the operating pressure of the venting device.

[0036] In a pack case according to an embodiment of the present invention, when the internal pressure of the pack increases and the relatively thin lid expands, the venting mechanism built into the restraint releases the pressure before the lid reaches its limit of volumetric expansion and collapses, thereby delaying and suppressing the collapse of the lid's structure when a heat propagation event occurs.

[0037] Furthermore, since the venting mechanism built into the restraint is configured to operate before the venting device provided in the pack housing, even in a situation where the internal pressure rises suddenly and the venting device cannot yet operate, the venting mechanism of the restraint operates first, preventing damage to the pack case while ensuring time for the venting device to operate normally.

[0038] Hereinafter, a specific embodiment of a pack case 10 according to one embodiment of the present invention will be described in detail with reference to the accompanying drawings. For reference, the directions of front, back, up, down, left, and right that specify relative positions used in the following description are intended to aid in understanding the invention, and unless otherwise specified, are based on the directions shown in the drawings.

[0039] (First embodiment) Fig. 1 is a diagram showing a pack case 10 according to one embodiment of the present invention, and Fig. 2 is an exploded perspective view of the pack case 10. Referring to Fig. 1 and Fig. 2, the pack case 10 according to one embodiment of the present invention includes a pack housing 100, a lid 200, and a restraint 300.

[0040] Pack housing 100 forms a space for accommodating at least one, and preferably multiple, battery modules (not shown). Pack housing 100 includes a base plate 110 that forms the bottom surface, and multiple side frames 120 that form wall surfaces on all four sides.

[0041] The pack housing 100 also includes a center beam 130 and / or cross beams 140 that form a plurality of spaces that separate and accommodate a plurality of battery modules. The center beam 130 and the cross beams 140 divide the spaces that accommodate the battery modules while also strengthening the rigidity of the entire pack case 10. As will be described later, in the pack case 10 according to one embodiment of the present invention, the height of the center beam 130 and / or the cross beams 140 is formed to be lower than the height of the side frames 120.

[0042] The lid 200 is a member that serves as a lid covering the open top surface of the pack housing 100. The lid 200 completes the closure or sealing of the pack housing 100. The lid 200 has lower rigidity than the base plate 110, side frames 120, center beam 130, and cross beam 140 that constitute the pack housing 100. Typically, the lid 200 is made of a relatively thin plate material. Because the lid 200 has relatively low rigidity, when the internal pressure of the pack case 10 increases, the lid 200 undergoes expansion and deformation, which has the effect of expanding the space inside the pack case 10. This volume expansion partially buffers the initial sudden increase in pressure that occurs when a thermal runaway or heat propagation event occurs.

[0043] However, there is a clear limit to the volumetric expansion of the lid 200 constrained by the pack housing 100, and therefore, the venting device 150 provided in the pack housing 100 must be activated to release the excessively increased internal pressure before the constrained state of the lid 200 is broken. However, in some cases, there may be a time delay before the venting device 150 is activated, and in this case, the lid 200, which cannot withstand the pressure, may rupture, causing an explosion of the battery pack.

[0044] The pack case 10 according to one embodiment of the present invention is able to properly release pressure before the venting device 150 of the pack housing 100 is activated, thereby maintaining a good restrained state of the lid 200. To this end, a pressure release function is provided to the restraining device 300 that secures the lid 200 to the pack housing 100. That is, the restraining device 300 that secures the lid 200 to the pack housing 100 incorporates a venting mechanism 310 that releases to the outside any pressure within the pack that exceeds a preset value.

[0045] Figure 3 is a cross-sectional view taken along line "AA" in Figure 1, and Figure 4 is an enlarged cross-sectional view of portion "B" in Figure 3. In one embodiment of the present invention, restraint 300 can be fixed to pack housing 100 by screwing lid 200. In particular, restraint 300 can be fastened to center beam 130 and / or cross beams 140 that traverse the interior of pack housing 100.

[0046] 2, the lid 200 is fixed along its edges to the side frames 120 of the pack housing 100. The lid 200 is tightly secured to the pack housing 100 by a plurality of bolts 400 that pass through and fasten to the side frames 120 along the edges of the lid 200. Meanwhile, the restraint 300 that secures the lid 200 to the center beam 130 and / or cross beams 140 leaves a small space between the inner surface of the lid 200 and the center beam 130 and / or cross beams 140 so that the pressure inside the pack can act on the built-in venting mechanism 310. In other words, the height of the center beam 130 and / or cross beams 140 is lower than that of the side frames 120, and as a result, the inner surface of the lid 200 is not tightly secured to the center beam 130 and / or cross beams 140. In this respect, the restraining device 300 does not tightly fix the lid 200 to the center beam 130 and / or the cross beams 140, but can prevent the lid 200 from coming off the pack case 10.

[0047] 3 and 4, the restraint device 300 includes a pressure inlet 330 that communicates with a space formed by the inner surface of the lid 200 relative to the center beam 130 and / or cross beam 140, and a pressure outlet 340 that is provided in a head 302 that protrudes from the outer surface of the lid 200 and communicates with the inner pressure inlet 330. A venting mechanism 310 is disposed between the pressure inlet 330 and the pressure outlet 340. In the illustrated embodiment, the venting mechanism 310 is configured with a valve mechanism 312 that is opened and closed by a spring 316. The valve mechanism 312 in the drawings includes a ball valve 314 and a spring 316. When pressure exceeding the preload set on the spring 316 acts from the pressure inlet 330, the ball valve 314 moves to open the pressure outlet 340.

[0048] The pack housing 100 is provided with at least one or more venting devices 150, and the venting mechanism 310 built into the restraint 300 can operate at a pressure lower than the operating pressure of the venting device 150. In other words, the venting mechanism 310 built into the restraint 300 operates before the venting device 150 when the pressure inside the pack rises. As a result, the volume expansion of the lid 200 and the operation of the venting mechanism 310 partially relieve and release the pressure inside the pack, preventing the structural collapse of the pack case 10 for a predetermined period of time, during which the venting device 150 begins operating, allowing the pressure inside the pack to be smoothly released.

[0049] (Second embodiment) Figure 5 is a diagram illustrating another embodiment of restraint 300. In the embodiment of Figure 5, venting mechanism 310 comprises rupture disk 318 positioned inside restraint 300 between pressure inlet 330 and pressure outlet 340.

[0050] The rupture disk 318 is a thin plate-shaped member made of a metal material, and has a notch formed on its surface. When thermal runaway occurs inside the pack case 10 and pressure rises, the pressure acts on the pressure inlet 330 of the restraint 300. The pressure transmitted from the pressure inlet 330 causes tensile deformation throughout the rupture disk 318, whose edge is fixed inside the restraint 300, and the weak notch breaks, opening the pressure outlet 340.

[0051] FIGS. 6 and 7 are views illustrating modified embodiments of the restraint device 300 shown in FIG. 5 . According to the embodiment of FIG. 6 , the venting mechanism 310 may further include a mesh member 320 disposed between the pressure inlet 330 and the rupture disk 318. The mesh member 320 is a sheet-like structure having numerous small holes and can perform a filtering function. That is, by covering the upstream side of the pressure outlet 340 of the venting mechanism 310 with the mesh member 320, high-temperature particles mixed with the venting gas are filtered by the mesh member 320 and are not discharged to the outside. In particular, high-temperature particles exceeding a certain size can act as an ignition source for an external fire. Therefore, filtering by the mesh member 320 can effectively eliminate the cause of external ignition. For reference, the mesh size of the mesh member 320 shown in the figure is exaggerated for clarity; it goes without saying that the mesh member 320 may be smaller in size.

[0052] Furthermore, the mesh member 320 may be a porous member made of a thermally conductive material, which provides both a filtering function and a flame-extinguishing function. The thermally conductive porous mesh member 320 absorbs heat generated from the burning gas mixture and dissipates it to the surrounding area, thereby lowering the combustion temperature so that the surrounding gas does not rise to its spontaneous combustion temperature. This is because the high-temperature gas absorbs heat from the thermally conductive porous structure as it passes through the mesh member 320. Therefore, a flame generated by thermal runaway within the pack case 10 absorbs enough heat to no longer be able to sustain the flame as it passes through the mesh member 320, which is located upstream of the pressure outlet 340 of the venting mechanism 310, thereby suppressing heat propagation and external fires.

[0053] 7, a capsule 322 in which a liquid fire-extinguishing agent 324 is sealed can be provided in the space formed between the rupture disk 318 and the mesh member 320. The sealed liquid fire-extinguishing agent 324 absorbs the heat of the high-temperature gas, vaporizes, and expands rapidly in volume, so that the capsule 322 can burst from the inside.

[0054] The provision of capsules 322 sealed with liquid fire-extinguishing agent 324 within restraint device 300 enables rapid response to the early stages of a fire caused by thermal runaway. By using liquid fire-extinguishing agent 324, its volume expands explosively during the vaporization process, enabling effective fire-extinguishing performance while occupying a small space. For effective fire-extinguishing, it is preferable for capsule 322 to rupture before rupture disk 318. By appropriately selecting the material of capsule 322, it is possible to design the liquid fire-extinguishing agent 324 to sufficiently vaporize below the temperature at which the pressure level at which rupture disk 318 ruptures can be reached. Rupture of capsule 322 before rupture disk 318 allows for more effective fire-extinguishing while maintaining the sealed interior of pack case 10.

[0055] In the embodiment of FIG. 7 , the liquid fire extinguishing agent 324 may be a fluorinated ketone. Fluorinated ketones are artificially created by substituting fluorine for hydrogen atoms in ketones. They are colorless, odorless, and have a viscosity similar to that of water, making them easy to incorporate into capsules 322. The stable fluorine provides a dielectric strength more than twice that of nitrogen, making them non-conductive and non-reactive with materials they come into contact with. Furthermore, their extremely low surface tension allows them to spread easily without forming droplets upon contact with objects, making them highly suitable for fire extinguishing. Furthermore, fluorinated ketones are non-toxic and harmless to humans, and they rapidly evaporate upon contact with fire or smoke, making them an effective fire retardant that quickly removes heat. They are also more environmentally friendly than conventional fire extinguishing agents because they leave no residue after evaporation. In particular, the non-conductivity provided by the stable properties of fluorine makes them suitable for use in combating fires caused by thermal runaway in secondary batteries.

[0056] However, since the boiling point of fluorinated ketone is 49°C, which is much lower than that of water, it exists in liquid form at room temperature but quickly evaporates when the temperature rises. Therefore, the material and thickness of capsule 322 containing the liquid fluorinated ketone must be designed so that it can properly function as an insulator.

[0057] The present invention has been described in more detail above with reference to the drawings and embodiments, etc. However, the configurations shown in the drawings or embodiments in this specification are merely one embodiment of the present invention and do not represent all of the technical ideas of the present invention, and therefore, at the time of filing this application, there may be various equivalents and modifications that can replace them. [Explanation of symbols]

[0058] 10: Pack case 100: Pack housing 110: Base plate 120: Side frame 130: Center beam 140: Cross beam 150: Venting equipment 200: Lid 300: Restraints 302: Head 310: Venting mechanism 312: Valve mechanism 314: Ball valve 316: Spring 318: Rupture Disc 320: Mesh material 322: Capsule 324: Liquid fire extinguishing agent 330: Pressure inlet 340: Pressure outlet 400: Volts

Claims

1. A pack housing; a lid for covering the open top surface of the pack housing; Including, A pack case, wherein a restraining device that fixes the lid to the pack housing has a built-in venting mechanism that releases pressure inside the pack that exceeds a preset value to the outside.

2. The restraint device is The pack case according to claim 1 , wherein the lid is fixed to the pack housing by fastening with screws.

3. The restraint device is The pack case according to claim 2 , which is fastened to a center beam and / or cross beams that traverse the interior of the pack housing.

4. The restraint device is a pressure inlet communicating with a space defined by an inner surface of the lid relative to the center beam and / or cross beam; The pack case according to claim 3 , further comprising: a pressure outlet provided in a head projecting from the outer surface of the lid and communicating with the pressure inlet.

5. the lid is fixed to a side frame of the pack case along an edge thereof, The pack case according to claim 4 , wherein the restraining device prevents the lid from separating from the pack case.

6. The pack housing is provided with at least one venting device; The pack case according to any one of claims 1 to 5, wherein the venting mechanism built into the restraint device operates at a pressure lower than the operating pressure of the venting device.

7. The venting mechanism includes: The pack case according to claim 6, wherein the restraining device is a valve mechanism disposed between the pressure inlet and the pressure outlet, and opened and closed by a spring.

8. The venting mechanism includes: The pack case according to claim 6, wherein the restraining device is a rupture disk disposed between the pressure inlet and the pressure outlet.

9. The venting mechanism includes: The pack case according to claim 8, further comprising a mesh member disposed between the pressure inlet and the rupture disk.

10. The pack case according to claim 9, wherein a capsule in which a liquid fire extinguishing agent is sealed is provided in a space formed between the rupture disk and the mesh member.

11. The capsule comprises: The pack case according to claim 10, which explodes when the liquid fire-extinguishing agent vaporizes.

12. The capsule comprises: The pack case according to claim 11, which ruptures before the rupture disk.

13. The pack case according to claim 12, wherein the liquid fire extinguishing agent is a fluorinated ketone.

Images