Pack case

Abstract

The disclosed pack case comprises: a pack housing; and a lid that covers the open upper surface of the pack housing, wherein fasteners for fixing the lid to the pack housing are each equipped with a venting mechanism for discharging, to the outside, pressure in the pack that exceeds a preset value.

Description

Pack Case

[0001] The present invention relates to a pack case capable of maintaining the sealed structure of a lead bound to a pack housing for a longer period of time when a thermal runaway occurs.

[0002] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2023-0114714, dated August 30, 2023, the entire contents of which are incorporated herein by reference.

[0003] Unlike primary batteries, secondary batteries are rechargeable and, due to their potential for miniaturization and large capacity, have been the subject of extensive research and development in recent years. With increasing technological development and demand for mobile devices, and the emergence of electric vehicles and energy storage systems in response to the era's growing environmental concerns, demand for secondary batteries as an energy source is rapidly increasing.

[0004] Secondary batteries are classified into coin-shaped, cylindrical, square, and pouch-shaped batteries, depending on the shape of their battery cases. In secondary batteries, the electrode assembly mounted inside the battery case is a rechargeable, power-generating element comprised of a laminated structure of electrodes and a separator.

[0005] Because secondary batteries require continuous, long-term use, effective control of the heat generated during charging and discharging is essential. If secondary batteries are not properly cooled, a temperature rise triggers an increase in current, which in turn triggers a temperature rise, resulting in a positive feedback loop, ultimately leading to a catastrophic condition known as thermal runaway.

[0006] In addition, when secondary batteries are grouped in the form of modules or packs, a thermal propagation phenomenon occurs in which thermal runaway in one secondary battery causes other secondary batteries in the vicinity to be continuously overheated. That is, when thermal runaway occurs in a battery module within a battery pack, a large amount of conductive dust, gas, and flames are ejected from the high-voltage terminals of the battery module, and as a result, dust accumulates on the high-voltage terminals of other adjacent battery modules, and the thermal propagation phenomenon is triggered by heat transfer by the gas and flames.

[0007] When heat transfer occurs in a battery pack, the pressure and temperature inside the pack rise rapidly. To withstand these pressure and temperature surges, the battery pack must maintain structural integrity for a significant period of time. If the battery pack collapses and outside air enters, the combustion reaction can rapidly intensify, posing a significant risk of fire or explosion outside the pack.

[0008] In a structure that covers and restrains the lead for the housing of the battery pack, there is a limit to the increase in volume inside the battery pack, and when an event such as heat transfer occurs, pressure is not released instantaneously, so the structure of the pack may collapse before the venting device operates, causing flames to erupt to the outside.

[0009] Inhibiting and delaying thermal runaway is a particularly crucial issue in electric vehicles, which can directly lead to fatalities. Related regulations are becoming increasingly stringent. This means that sufficient time is required before the battery pack experiences structural collapse, allowing ample time for emergency evacuation and safety measures after thermal runaway occurs. Therefore, measures must be developed to ensure that the leads, bound within the pack housing, maintain their sealed structure for a sufficient period of time.

[0010] The purpose of the present invention is to provide a pack case having a structure in which a lead is restrained with respect to a pack housing, wherein when a thermal runaway or heat transfer event occurs and the internal pressure rapidly increases, the internal pressure is appropriately relieved before the lead exceeds the limit of volume expansion, thereby preventing collapse of the pack case and securing time until a venting device operates.

[0011] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0012] The present invention relates to a pack case, and in one example, comprises a pack housing and a lid covering an open upper surface of the pack housing, wherein a restraint for securing the lid to the pack housing includes a venting mechanism for discharging pressure within the pack exceeding a preset value to the outside.

[0013] In one embodiment of the present invention, the restraint member can secure the lead to the pack housing by screwing.

[0014] The above restraint may be fastened to a center beam and / or a cross beam that crosses the interior of the pack housing.

[0015] The above restraint device has a pressure inlet communicating with a space formed by the inner surface of the lead with respect to the center beam and / or the cross beam, and a pressure outlet provided on a head protruding from the outer surface of the lead and communicating with the pressure inlet.

[0016] The lead is secured to a side frame of the pack case along an edge, and the restraint member can prevent the lead from being separated from the pack case.

[0017] And, the pack housing is provided with at least one venting device, and the venting device 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 disposed between the pressure inlet and the pressure outlet inside the restraint and is opened and closed by a spring.

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

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

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

[0022] The above capsule can be ruptured by vaporization of the liquid digestive agent.

[0023] The above capsule may rupture before the rupture disc.

[0024] For example, the liquid fire extinguishing agent may be a fluoroketone.

[0025] According to the pack case of the present invention as described above, when the internal pressure of the pack increases, the relatively thin lead expands and increases in volume, and before the limit of volume increase is reached and the structure of the lead collapses, the venting mechanism built into the restraint releases the pressure. Therefore, structural collapse of the lead is delayed and suppressed in the event of thermal runaway or heat transfer.

[0026] In addition, since the venting device built into the restraint is configured to operate before the venting device provided in the pack housing, even in a situation where the venting device cannot operate in time due to a sudden increase in internal pressure, the venting device of the restraint operates first, thereby preventing damage to the pack case and securing time for the venting device to operate normally.

[0027] However, the technical effects that can be obtained through the present invention are not limited to the above-described effects, and other effects that are 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 idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0029] FIG. 1 is a drawing illustrating a pack case according to one embodiment of the present invention.

[0030] Figure 2 is an exploded perspective view of the pack case.

[0031] Figure 3 is a cross-sectional view along line “AA” of Figure 1.

[0032] Figure 4 is an enlarged cross-sectional view of portion “B” of Figure 3.

[0033] Figure 5 is a drawing showing another embodiment of a restraint device.

[0034] Figures 6 and 7 are drawings each showing a modified embodiment of the restraint device shown in Figure 5.

[0035] The present invention can be modified in various ways and has many embodiments, and specific embodiments will be described in detail below.

[0036] However, this is not intended to limit the present invention to a specific embodiment, but should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

[0037] In the present invention, it should be understood that terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0038] Additionally, in the present invention, when a part such as a layer, film, region, or plate is described as being "on" another part, this includes not only cases where it is "directly above" the other part, but also cases where there is another part in between. Conversely, when a part such as a layer, film, region, or plate is described as being "under" another part, this includes not only cases where it is "directly below" the other part, but also cases where there is another part in between. Furthermore, in the present application, "being placed on" may include cases where it is placed below as well as above.

[0039]

[0040] The present invention relates to a pack case, and in one example, comprises a pack housing and a lid covering an open upper surface of the pack housing, wherein a restraint for securing the lid to the pack housing includes a venting mechanism for discharging pressure within the pack exceeding a preset value to the outside.

[0041] And, the pack housing may be provided with at least one venting device, and the venting device built into the restraint may operate at a pressure lower than the operating pressure of the venting device.

[0042] According to the pack case of the present invention, when the internal pressure of the pack increases, the relatively thin lead expands and increases in volume, and before the limit of volume increase is reached and the structure of the lead collapses, the venting mechanism built into the restraint releases the pressure. Therefore, structural collapse of the lead is delayed and suppressed when a heat transfer event occurs.

[0043] In addition, since the venting device built into the restraint is configured to operate before the venting device provided in the pack housing, even in a situation where the venting device cannot operate in time due to a sudden increase in internal pressure, the venting device of the restraint operates first, thereby preventing damage to the pack case and securing time for the venting device to operate normally.

[0044] Hereinafter, a specific embodiment of a pack case (10) according to the present invention will be described in detail with reference to the attached drawings. For reference, the directions of front / back, up / down / left / right, etc., used to designate relative positions in the following description are intended to aid understanding of the invention, and unless otherwise specifically defined, the directions shown in the drawings are taken as a reference.

[0045]

[0046] [First Embodiment]

[0047] FIG. 1 is a drawing illustrating 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 FIGS. 1 and 2, the pack case (10) of the present invention includes a pack housing (100), a lid (200), and a restraint (300).

[0048] The pack housing (100) forms a space for accommodating at least one, and preferably a plurality of, battery modules (not shown). The pack housing (100) includes a base plate (110) forming a bottom surface and a plurality of side frames (120) forming wall surfaces in all directions.

[0049] In addition, the pack housing (100) includes a center beam (130) and / or a cross beam (140) that form a plurality of spaces for separately accommodating a plurality of battery modules. The center beam (130) and the cross beam (140) divide the space for accommodating the battery modules, while also serving to reinforce the overall rigidity of the pack case (10). As will be described later, in the pack case (10) of the present invention, the height of the center beam (130) and / or the cross beam (140) is formed lower than the height of the side frame (120).

[0050] The lid (200) refers to a member that serves as a cover covering the open upper surface of the pack housing (100). The lid (200) completes the closing or sealing of the pack housing (100). The lid (200) has less rigidity than the base plate (110), side frame (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. Since the rigidity of the lid (200) is relatively small, when the internal pressure of the pack case (10) increases, the lid (200) undergoes expansion deformation, thereby obtaining the effect of expanding the space inside the pack case (10). By this volume expansion, the initial rapid pressure increase that occurs when a thermal runaway or heat transfer event occurs is partially buffered.

[0051] However, the limit of volume expansion of the lead (200) bound to the pack housing (100) is clear, and therefore, before the restraint state of the lead (200) is destroyed, the venting device (150) provided in the pack housing (100) must operate to relieve the excessively increased internal pressure. However, in some cases, a time delay may occur before the venting device (150) operates, and in this case, the lead (200) that cannot withstand the pressure may burst, resulting in an explosion of the battery pack.

[0052] The pack case (10) of the present invention can maintain a good binding state of the lid (200) by appropriately releasing pressure before the venting device (150) of the pack housing (100) operates. To this end, a pressure releasing function is provided to the binding device (300) that secures the lid (200) to the pack housing (100). That is, the binding device (300) that secures the lid (200) to the pack housing (100) has a built-in venting device (310) that releases to the outside the pressure inside the pack that exceeds a preset value.

[0053] Fig. 3 is a cross-sectional view taken along line "AA" of Fig. 1, and Fig. 4 is an enlarged cross-sectional view of portion "B" of Fig. 3. In one embodiment of the present invention, the restraint (300) can secure the lead (200) to the pack housing (100) by screw fastening. In particular, the restraint (300) can be fastened to the center beam (130) and / or the cross beam (140) that cross the interior of the pack housing (100).

[0054] Referring to Fig. 2, the lead (200) is fixed to the side frame (120) of the pack housing (100) along its edge. The lead (200) is tightly fixed to the pack housing (100) by a plurality of bolts (400) that penetrate and are fastened to the side frame (120) along the edge of the lead (200). On the other hand, the restraint (300) that fixes the lead (200) to the center beam (130) and / or the cross beam (140) has a slight space formed between the inner surface of the lead (200) and the center beam (130) and / or the cross beam (140) so that the pressure within the pack can act on the built-in venting mechanism (310). That is, the height of the center beam (130) and / or the cross beam (140) is lower than that of the side frame (120), and accordingly, the inner surface of the lead (200) is not in close contact with the center beam (130) and / or the cross beam (140). In this respect, the restraint (300) does not tightly fix the lead (200) to the center beam (130) and / or the cross beam (140), but can suppress the lead (200) from being separated from the pack case (10).

[0055] Referring to FIGS. 3 and 4, the restraint (300) has a pressure inlet (330) communicating with a space formed by the inner surface of the lead (200) with respect to the center beam (130) and / or the cross beam (140), and a pressure outlet (340) provided on a head (302) protruding from the outer surface of the lead (200) and communicating with the inner pressure inlet (330). In addition, a venting mechanism (310) is arranged between the pressure inlet (330) and the pressure outlet (340), and in the illustrated embodiment, the venting mechanism (310) is composed of a valve mechanism (312) that is opened and closed by a spring (316). The valve mechanism (312) in the drawing includes a ball valve (314) and a spring (316), and when a 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).

[0056] And, the pack housing (100) is provided with at least one venting device (150), and the venting device (310) built into the restraint (300) can operate at a pressure lower than the operating pressure of the venting device (150). That is, the venting device (310) built into the restraint (300) operates before the venting device (150) when the pressure inside the pack increases. Accordingly, the pressure inside the pack is partially relieved and discharged by the volume expansion of the lid (200) and the operation of the venting device (310), thereby suppressing the structural collapse of the pack case (10) for a predetermined period of time, and during this time, the venting device (150) starts operating, so that the pressure inside the pack is smoothly discharged.

[0057]

[0058] [Second Embodiment]

[0059] Fig. 5 is a drawing illustrating another embodiment of a restraint device (300). In the embodiment of Fig. 5, the venting mechanism (310) is composed of a rupture disk (318) disposed between a pressure inlet (330) and a pressure outlet (340) inside the restraint device (300).

[0060] The rupture disk (318) is a thin plate-shaped member made of metal, and has a notch formed on the surface by notching. When thermal runaway occurs within the pack case (10) and the pressure increases, this pressure acts on the pressure inlet (330) of the restraint (300). Due to the pressure transmitted from the pressure inlet (330), tensile deformation occurs throughout the rupture disk (318) whose rim is fixed within the restraint (300), and then the weak notch is torn, opening the pressure outlet (340).

[0061] FIGS. 6 and 7 are drawings each illustrating a modified embodiment of the restraint device (300) illustrated in FIG. 5. According to the embodiment of FIG. 6, the venting mechanism (310) may further include a mesh member (320) installed between the pressure inlet (330) and the rupture disk (318). The mesh member (320) refers to a sheet-shaped structure having a plurality of small holes and may perform a filtering function. That is, since the mesh member (320) covers the upstream of the pressure outlet (340) of the venting mechanism (310), high-temperature particles mixed in the venting gas are filtered by the mesh member (320) and are not discharged to the outside. In particular, since high-temperature particles exceeding a certain size act as an ignition source for an external fire, the cause of external ignition can be effectively removed through filtering by the mesh member (320). For reference, the eye size of the mesh member (320) shown is exaggerated for clarity, and it is of course possible for the eye size of the mesh member (320) to be formed smaller than this.

[0062] Furthermore, the mesh member (320) may be provided as a porous member made of a thermally conductive material. This is designed to take into account not only the filtering function but also the flame extinguishing function. The porous mesh member (320) made of a thermally conductive material absorbs the heat generated from the combustible gas mixture and dissipates it to the surroundings, thereby lowering the combustion temperature so that the surrounding gas does not reach its autoignition temperature. This is because the high-temperature gas loses heat to the thermally conductive porous structure as it passes through the mesh member (320). Therefore, the flame generated by thermal runaway inside the pack case (10) loses an amount of heat that the flame can no longer sustain as it passes through the mesh member (320) arranged upstream of the pressure outlet (340) of the venting device (310), thereby suppressing the heat propagation phenomenon or external fire.

[0063] Furthermore, as in the embodiment illustrated in FIG. 7, a capsule (322) in which a liquid extinguishing agent (324) is sealed may be provided in the space formed between the rupture disk (318) and the mesh member (320). The capsule (322) may be ruptured from the inside as the sealed liquid extinguishing agent (324) absorbs the heat of the high-temperature gas, thereby vaporizing and rapidly expanding in volume.

[0064] By providing a capsule (322) containing a liquid extinguishing agent (324) sealed inside the restraint device (300), a rapid response is possible in the early stages of a fire caused by thermal runaway. By using the liquid extinguishing agent (324), the volume expands explosively during the vaporization process, so that an effective fire extinguishing function can be expected while occupying a small space. For an effective fire extinguishing effect, it may be desirable for the capsule (322) to rupture before the rupture disk (318). By appropriately selecting the material of the capsule (322), it can be designed so that the liquid extinguishing agent (324) sufficiently vaporizes below the temperature formed at the pressure level at which the rupture disk (318) ruptures. By rupturing the capsule (322) before the rupture disk (318), the fire extinguishing effect can be more effectively performed while maintaining the seal inside the pack case (10).

[0065] In the embodiment of FIG. 7, the liquid fire extinguishing agent (324) may be a fluorinated ketone. Fluorinated ketone is an artificially created substance by replacing hydrogen atoms in ketone with fluorine. It is colorless and odorless, and its viscosity is almost the same as water, making it easy to contain in a capsule (322). Due to the stable nature of fluorine, its insulating strength is more than twice that of nitrogen, so it does not conduct electricity and does not react, such as oxidize, with substances it comes into contact with. In addition, because its surface tension is very low, it does not form droplets when it comes into contact with an object and spreads well, making it very suitable for fire extinguishing. In addition, fluorinated ketone is non-toxic and harmless to the human body because it evaporates quickly upon contact with fire or smoke, making it an effective fire retardant that also quickly removes heat. Since it does not leave residue after evaporation, it is more environmentally friendly than existing fire extinguishing agents. In particular, the non-conductive nature of fluorine, which is a stable property, makes it suitable for responding to fires caused by thermal runaway of secondary batteries.

[0066] However, since fluoroketone has a boiling point of 49°C, much lower than water, it exists in a liquid state at room temperature but rapidly vaporizes when the temperature rises. Therefore, it is necessary to design the material and thickness of the capsule (322) containing the liquid fluoroketone so that it can properly function as an insulator.

[0067]

[0068] The present invention has been described in more detail through drawings and examples. However, the configurations described in the drawings or examples described in this specification are merely embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

[0069]

[0070] [Explanation of symbols]

[0071] 10: Pack Case 100: Pack Housing

[0072] 110: Base plate 120: Side frame

[0073] 130: Center beam 140: Cross beam

[0074] 150: Venting device 200: Lead

[0075] 300: Restraint 302: Head

[0076] 310: Venting mechanism 312: Valve mechanism

[0077] 314: Ball valve 316: Spring

[0078] 318: Rupture disc 320: Mesh absence

[0079] 322: Capsule 324: Liquid digestive medicine

[0080] 330: Pressure inlet 340: Pressure outlet

[0081] 400: Volt

Claims

1. Pack housing; and A lid covering the open upper surface of the pack housing; Including, A pack case in which the restraint device for fixing the lead to the pack housing has a built-in venting mechanism for discharging pressure within the pack exceeding a preset value to the outside.

2. In paragraph 1, The above restraints are, A pack case, wherein the lead is secured to the pack housing by a screw connection.

3. In paragraph 2, The above restraints are, A pack case, which is fastened to a center beam and / or cross beam extending across the interior of the pack housing.

4. In paragraph 3, The above restraints are, A pressure inlet communicating with the space formed by the inner surface of the lead for the center beam and / or cross beam, A pack case having a head protruding from the outer surface of the above lead and having a pressure outlet communicating with the pressure inlet.

5. In paragraph 4, The above lead is fixed to the side frame of the pack case along the edge, The above restraint device is a pack case that prevents the lead from being separated from the pack case.

6. In paragraph 1, The above pack housing is provided with at least one venting device, The venting device built into the above restraint device is a pack case that operates at a pressure lower than the operating pressure of the venting device.

7. In paragraph 6, The above venting device is, A pack case, which is a valve mechanism that is placed between the pressure inlet and the pressure outlet inside the above-mentioned restraint device and is opened and closed by a spring.

8. In paragraph 6, The above venting device is, A pack case, which is a rupture disk disposed between the pressure inlet and the pressure outlet inside the above-mentioned restraint device.

9. In paragraph 8, The above venting device is, A pack case further comprising a mesh member installed between the pressure inlet and the rupture disk.

10. In paragraph 9, A pack case in which a capsule containing a liquid extinguishing agent is sealed is provided in the space formed between the above rupture disk and the mesh member.

11. In paragraph 10, The above capsule, A pack case that bursts due to vaporization of the above liquid fire extinguishing agent.

12. In paragraph 11, The above capsule, A pack case that ruptures before the above rupture disc.

13. In paragraph 12, The above liquid fire extinguishing agent is a fluoroketone, pack case.

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