Pack case

Abstract

The disclosed invention relates to a pack case, wherein, in one example, it comprises a pack housing and a lid covering an open upper surface of the pack housing, and a restraining member that secures the lid to the pack housing incorporates a venting mechanism that discharges pressure inside the pack exceeding a preset value to the outside.

Description

Technology Field

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

[0002] Unlike primary batteries, secondary batteries are rechargeable and are currently the subject of extensive research and development due to their potential for miniaturization and high capacity. The demand for secondary batteries as an energy source is increasing rapidly due to the growing technological development and demand for mobile devices, as well as the rise of electric vehicles and energy storage systems driven by the contemporary need for environmental protection.

[0003] Rechargeable batteries are classified into coin batteries, cylindrical batteries, prismatic batteries, and pouch batteries according to the shape of the battery case. In rechargeable batteries, the electrode assembly mounted inside the battery case is a power generation device capable of charging and discharging, consisting of a laminated structure of electrodes and separators.

[0004] Since secondary batteries require continuous use over long periods, it is necessary to effectively control the heat generated during the charging and discharging process. If the cooling of the secondary battery is not performed smoothly, a positive feedback chain reaction occurs where the temperature rise causes an increase in current, and this increase in current again causes a temperature rise, eventually leading to a catastrophic state of thermal runaway.

[0005] In addition, when secondary batteries are grouped in the form of modules or packs, a thermal propagation phenomenon occurs in which surrounding secondary batteries are continuously overheated due to thermal runaway in one secondary battery. 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 terminal of the battery module, and consequently, dust accumulates on the high-voltage terminal of an adjacent battery module, and the thermal propagation phenomenon is triggered by heat transfer from the gas and flames.

[0006] When thermal propagation occurs within a battery pack, the internal pressure and temperature rise rapidly. To withstand this surge in pressure and temperature, the battery pack must maintain structural robustness for a significant period. If the battery pack collapses and external air enters, combustion reactions intensify rapidly, posing a major risk to the exterior of the pack, such as fire or explosion.

[0007] In a structure where the lead covers and restrains the battery pack housing, there is a limit to the increase in the internal volume of the battery pack. Furthermore, in the event of an event such as thermal propagation, pressure is not released instantaneously, which can cause the pack structure to collapse and flames to be ejected to the outside before the venting device operates.

[0008] The suppression and delay of thermal propagation are treated as critical issues, particularly in electric vehicles where they are directly linked to human casualties, and related regulations are becoming increasingly stringent. Specifically, sufficient time delays are required before the battery pack undergoes structural collapse to ensure sufficient time for emergency evacuation and safety measures following a thermal runaway. Therefore, it is necessary to devise a method that allows the leads confined within the pack housing to maintain a sealed structure for a sufficient period of time. Prior art literature

[0009] Korean Patent Publication No. 10-2012-0007380 (Published Jan. 20, 2012) The problem to be solved

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

[0011] However, the technical problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems will be clearly understood by a person skilled in the art from the description of the invention below. means of solving the problem

[0012] The present invention relates to a pack case, wherein, in one example, it comprises a pack housing and a lid covering an open upper surface of the pack housing, and a restraining member that secures the lid to the pack housing incorporates a venting mechanism that discharges pressure inside the pack exceeding a preset value to the outside.

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

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

[0015] The above restraint comprises a pressure inlet communicating with the space formed by the inner surface of the lead with respect to the center beam and / or 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 fixed to the side frame of the pack case along the edge, and the restraint can prevent the lead from detaching from the pack case.

[0017] In addition, the pack housing is equipped with at least one venting device, and the venting mechanism embedded in 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 disposed between the pressure inlet and pressure outlet inside the restraint and 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 inside 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 sealed liquid fire extinguishing agent may be provided in the space formed between the rupture disc and the mesh member.

[0022] The above capsule may rupture due to the vaporization of the liquid fire extinguishing agent.

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

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

[0025] According to the pack case of the present invention as described above, when a relatively thin lead expands and increases in volume as the internal pressure of the pack rises, a venting mechanism embedded in the restraint releases the pressure before the structure of the lead collapses upon reaching the limit of volume increase. Therefore, the structural collapse of the lead is delayed and suppressed in the event of thermal runaway or thermal propagation events.

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

[0027] However, the technical effects obtainable through the present invention are not limited to those described above, and other unmentioned effects will be clearly understood by a person skilled in the art from the description of the invention below. Brief explanation of the drawing

[0028] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. FIG. 1 is a drawing illustrating a pack case according to one embodiment of the present invention. FIG. 2 is an exploded perspective view of the pack case. FIG. 3 is a cross-sectional view along the line "AA" in FIG. 1. FIG. 4 is an enlarged cross-sectional view of section "B" of FIG. 3. FIG. 5 is a drawing illustrating another embodiment of the restraint device. FIGS. 6 and FIGS. 7 are drawings illustrating modified embodiments of the restraint shown in FIGS. 5, respectively. Specific details for implementing the invention

[0029] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are to be described in detail below.

[0030] However, this is not intended to limit the invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0031] In the present invention, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0032] Furthermore, 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 "immediately 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 "immediately below" the other part, but also cases where there is another part in between. Additionally, in the present application, being "placed on" may include cases where it is placed on the lower part as well as on the upper part.

[0034] The present invention relates to a pack case, wherein, in one example, it comprises a pack housing and a lid covering an open upper surface of the pack housing, and a restraining member that secures the lid to the pack housing incorporates a venting mechanism that discharges pressure inside the pack exceeding a preset value to the outside.

[0035] In addition, the pack housing may be equipped with at least one venting device, and the venting mechanism embedded in the restraint may operate at a pressure lower than the operating pressure of the venting device.

[0036] According to the pack case of the present invention, when a relatively thin lead expands and increases in volume as the internal pressure of the pack rises, a venting mechanism embedded in the restraint releases the pressure before the lead's structure collapses upon reaching the limit of volume increase. Consequently, the collapse of the lead's structure is delayed and suppressed in the event of a heat propagation event.

[0037] In addition, since the venting mechanism built into the restraint is configured to operate before the venting device provided in the pack housing, even in situations where the venting device cannot operate due to a sudden and rapid increase in internal pressure, the venting mechanism of the restraint operates first, thereby preventing damage to the pack case while securing a time margin for the venting device to operate normally.

[0039] Hereinafter, specific embodiments of the 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, and right used to specify relative positions in the following description are intended to aid in understanding the invention, and unless otherwise specifically defined, the directions shown in the drawings are used as the reference.

[0041] [First embodiment]

[0042] FIG. 1 is a drawing illustrating a pack case (10) according to an 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) of the present invention includes a pack housing (100), a lid (200), and a restraining member (300).

[0043] The pack housing (100) forms a space for accommodating at least one, 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 walls on all sides.

[0044] Additionally, the pack housing (100) includes a center beam (130) and / or a cross beam (140) that form a plurality of spaces for accommodating a plurality of battery modules separately. The center beam (130) and the cross beam (140) serve to divide the spaces for accommodating the battery modules while reinforcing 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 to be lower than the height of the side frame (120).

[0045] The lid (200) refers to a member that serves as a cover for the open upper surface of the pack housing (100). The closure or sealing of the pack housing (100) is completed by the lid (200). The lid (200) has less rigidity compared to 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 plate material with a relatively thin thickness. As the rigidity of the lid (200) is relatively low, when the internal pressure of the pack case (10) rises, the lid (200) undergoes an expanding deformation, thereby achieving the effect of expanding the space inside the pack case (10). Due to this volume expansion, the rapid pressure rise at the beginning of a thermal runaway or thermal propagation event is partially buffered.

[0046] However, the limit of volume expansion of the lead (200) constrained in the pack housing (100) is clear, and therefore, before the constrained state of the lead (200) is destroyed, the venting device (150) provided in the pack housing (100) must operate to release the excessively increased internal pressure. However, in some cases, there may be a time delay before the venting device (150) operates, and in such cases, the lead (200) that cannot withstand the pressure may burst, and an explosion of the battery pack may occur.

[0047] The pack case (10) of the present invention is configured to properly discharge pressure before the venting device (150) of the pack housing (100) operates, thereby maintaining the restraint state of the lid (200) in good condition. To this end, a pressure discharge function is provided to the restraining member (300) that secures the lid (200) to the pack housing (100). That is, the restraining member (300) that secures the lid (200) to the pack housing (100) incorporates a venting mechanism (310) that discharges pressure inside the pack exceeding a preset value to the outside.

[0048] FIG. 3 is a cross-sectional view along the line "AA" of FIG. 1, and FIG. 4 is an enlarged cross-sectional view of the "B" portion 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 a center beam (130) and / or a cross beam (140) that cross the interior of the pack housing (100).

[0049] Referring to FIG. 2, the lid (200) is secured to the side frame (120) of the pack housing (100) along its edge. The lid (200) is secured in close contact with the pack housing (100) by a plurality of bolts (400) that are fastened through the side frame (120) along the edge of the lid (200). On the other hand, the restraint (300) securing the lid (200) to the center beam (130) and / or cross beam (140) has a small space formed between the inner surface of the lid (200) and the center beam (130) and / or cross beam (140) so that pressure within the pack can act on the venting mechanism (310) built into it. That is, the height of the center beam (130) and / or cross beam (140) is lower than that of the side frame (120), and accordingly, the inner surface of the lid (200) is not in close contact with the center beam (130) and / or cross beam (140). In this respect, the restraint (300) does not secure the lead (200) in close contact with the center beam (130) and / or cross beam (140), but can prevent the lead (200) from coming out of the pack case (10).

[0050] Referring to FIGS. 3 and 4, the restraint (300) has a pressure inlet (330) communicating with the space formed by the inner surface of the lead (200) with respect to the center beam (130) and / or 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). A venting mechanism (310) is disposed 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) is applied from the pressure inlet (330), the ball valve (314) moves to open the pressure outlet (340).

[0051] Additionally, the pack housing (100) is equipped with at least one venting device (150), and the venting mechanism (310) embedded in the restraint (300) can operate at a pressure lower than the operating pressure of the venting device (150). That is, the venting mechanism (310) embedded in the restraint (300) operates before the venting device (150) when the pressure inside the pack rises. 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 mechanism (310), thereby suppressing the structural collapse of the pack case (10) for a predetermined period of time, and during this time, the pressure inside the pack is smoothly discharged as the venting device (150) starts operating.

[0053] [Second embodiment]

[0054] FIG. 5 is a drawing illustrating another embodiment of the restraint (300). In the embodiment of FIG. 5, the venting mechanism (310) is composed of a rupture disc (318) disposed between the pressure inlet (330) and the pressure outlet (340) inside the restraint (300).

[0055] The rupture disc (318) is a thin plate-shaped member made of metal, with a notch formed on its surface. When thermal runaway occurs within the pack case (10) and the pressure rises, 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 disc (318), which has a fixed rim inside the restraint (300), and the notch, which has weak strength, tears, thereby opening the pressure outlet (340).

[0056] FIGS. 6 and FIGS. 7 are drawings illustrating modified embodiments of the restraint device (300) shown in FIG. 5, respectively. 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 can perform a filtering function. That is, the mesh member (320) covers the upstream of the pressure outlet (340) of the venting mechanism (310), so that 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 external fires, the cause of external ignition can be effectively eliminated through filtering by the mesh member (320). For reference, the eye size of the illustrated mesh member (320) is drawn in an exaggerated manner for clarity, and it goes without saying that the eye size of the mesh member (320) can be formed smaller than this.

[0057] Furthermore, the mesh member (320) may be provided as a porous member made of a thermally conductive material. This is intended to take into account the flame-extinguishing function in addition to the filtering function. The porous mesh member (320) made of a thermally conductive material absorbs heat generated from the burning gas mixture and radiates it to the surroundings, thereby lowering the combustion temperature so that the surrounding gas does not rise to the spontaneous ignition temperature. This is because heat is lost to the thermally conductive porous structure as the high-temperature gas passes through the mesh member (320). Therefore, the flame generated by thermal runaway inside the pack case (10) loses enough heat to no longer sustain the flame as it passes through the mesh member (320) placed upstream of the pressure outlet (340) of the venting mechanism (310), thereby suppressing heat propagation phenomena or external fires.

[0058] Furthermore, as in the embodiment illustrated in FIG. 7, a capsule (322) containing a liquid fire extinguishing agent (324) may be provided in the space formed between the rupture disk (318) and the mesh member (320). The capsule (322) may rupture from the inside as the sealed liquid fire extinguishing agent (324) absorbs the heat of the high-temperature gas and, consequently, vaporizes and rapidly expands in volume.

[0059] By providing a capsule (322) containing a liquid fire extinguishing agent (324) sealed inside a restraint (300), rapid response to a fire caused by thermal runaway is possible in the early stages. Since the volume of the liquid fire extinguishing agent (324) expands explosively during the vaporization process, effective fire extinguishing function can be expected while occupying a small space. For effective fire extinguishing action, it may be desirable for the capsule (322) to rupture before the rupture disc (318). By appropriately selecting the material of the capsule (322), the design can be such that the liquid fire extinguishing agent (324) sufficiently vaporizes at a temperature below the pressure level at which the rupture disc (318) ruptures. By causing the capsule (322) to rupture before the rupture disc (318), fire extinguishing action can be performed more effectively while maintaining the seal inside the pack case (10).

[0060] In the embodiment of FIG. 7, the liquid fire extinguishing agent (324) may be a fluorinated ketone. Fluorinated ketone is a substance artificially created by replacing hydrogen atoms in a 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 properties of fluorine, its dielectric strength is more than twice that of nitrogen, so it does not conduct electricity and does not cause reactions such as oxidation with contacted materials. Furthermore, because its surface tension is very low, it does not form water droplets when in contact with an object and spreads well, making it very suitable for fire extinguishing action. In addition, fluorinated ketone has the property of extinguishing fire while being non-toxic and harmless to the human body. It is an effective fire extinguisher that rapidly absorbs heat as soon as it comes into contact with fire or smoke, and it is more environmentally friendly than conventional fire extinguishing materials because it does not remain after evaporation. In particular, the non-conductive properties resulting from the stable properties of fluorine make it suitable for responding to fires caused by thermal runaway in secondary batteries.

[0061] However, since fluorinated ketone has a boiling point of 49°C, which is much lower than that of 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, etc., of the capsule (322) containing the liquid fluorinated ketone so that it can properly function as an insulating material.

[0063] The present invention has been described in more detail above through drawings and embodiments. However, the configurations described in the drawings or embodiments described in this specification are merely one embodiment of the present invention and do not represent all technical concepts of the present invention; therefore, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application. Explanation of the symbols

[0064] 10: Pack Case 100: Pack Housing 110: Base plate 120: Side frame 130: Center beam 140: Cross beam 150: Venting device 200: Lead 300: Restraint 302: Head 310: Venting mechanism 312: Valve mechanism 314: Ball valve 316: Spring 318: Rupture Disc 320: Missing Mesh 322: Capsule 324: Liquid fire extinguishing agent 330: Pressure inlet 340: Pressure outlet 400: Bolt

Claims

Claim 1 A pack case comprising: a pack housing; and a lid covering an open upper surface of the pack housing; wherein a restraint securing the lid to the pack housing comprises a venting mechanism for discharging pressure inside the pack exceeding a preset value to the outside, a pressure inlet communicating with a space formed by the inner surface of the lid, and a pressure outlet provided on a head protruding to the outer surface of the lid communicating with the pressure inlet, wherein the pack housing is provided with at least one venting device, and the venting mechanism embedded in the restraint operates at a pressure lower than the operating pressure of the venting device. Claim 2 In claim 1, the restraining device is a pack case that secures the lead to the pack housing by screw fastening. Claim 3 In paragraph 2, the restraint is a pack case that is fastened to a center beam and / or cross beam that crosses the interior of the pack housing. Claim 4 delete Claim 5 A pack case according to claim 1, wherein the lead is fixed to the side frame of the pack case along the edge, and the restraining member prevents the lead from detaching from the pack case. Claim 6 delete Claim 7 In claim 1, the venting mechanism is a pack case, which is a valve mechanism disposed between the pressure inlet and pressure outlet inside the restraint and is opened and closed by a spring. Claim 8 In claim 1, the venting mechanism is a pack case, which is a rupture disc disposed between the pressure inlet and the pressure outlet inside the restraint. Claim 9 In claim 8, the above venting mechanism further comprises a mesh member installed between the pressure inlet and the rupture disk, a pack case. Claim 10 In claim 9, a pack case in which a capsule containing a liquid fire extinguishing agent is provided in the space formed between the rupture disc and the mesh member. Claim 11 In item 10, the above capsule is a pack case that ruptures by the vaporization of the above liquid fire extinguishing agent. Claim 12 In paragraph 11, the above capsule is a pack case that ruptures before the above rupture disc. Claim 13 In Clause 12, the above liquid fire extinguishing agent is a pack case, which is a fluorinated ketone.

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