Battery pack with variable coupling section to prevent structural collapse

Abstract

The battery pack according to the present invention may include a battery module, a pack tray that houses the battery module therein and is provided such that the upper end is open, a pack cover disposed on the upper portion of the pack tray so as to seal the accommodation space in which the battery module is housed, and a variable coupling portion that interconnects the pack tray and the pack cover and elastically couples the pack cover to the pack tray so that the accommodation space is variably expanded in response to an increase in pressure when an event occurs.

Description

Technical Field

[0001] The present invention relates to a battery pack, and more particularly, to a battery pack capable of delaying the accumulation of thermal energy due to vent gas, flame, etc. generated during ignition inside a battery module and the structural collapse of the battery pack due to an increase in internal pressure.

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0117728 filed on September 19, 2022, and all of the content disclosed in the specification and drawings of the application is incorporated into this application.

Background Art

[0003] A secondary battery that converts electrical energy into chemical energy and can be repeatedly charged and discharged is called a secondary battery, distinguished from a disposable primary battery.

[0004] Secondary batteries include lithium secondary batteries, nickel cadmium (Ni-Cd) batteries, lead storage batteries, nickel metal hydride (Ni-MH) batteries, air zinc batteries, alkaline manganese batteries, etc. Among these, it can be said that lead storage batteries and lithium secondary batteries are the most actively commercialized secondary batteries.

[0005] In particular, lithium secondary batteries have a high energy storage density, can be lightweight and miniaturized, and due to advantages such as excellent safety, low discharge rate, and long life, their utilization as electric vehicle batteries has been active recently. For reference, lithium secondary batteries are usually divided into cylindrical, rectangular, and pouch types according to the manufacturing form, and in terms of usage, in addition to electric vehicle batteries, they are also used in ESS batteries and other electrical devices.

[0006] Currently, the operating voltage of a single lithium secondary battery cell is approximately 2.5V to 4.5V. Therefore, in order to use secondary batteries as an energy source for electric vehicles, a battery module is constructed by connecting multiple lithium-ion battery cells in series and / or parallel, and a battery pack is constructed by connecting these battery modules in series and / or parallel.

[0007] On the other hand, because secondary batteries undergo chemical reactions during charging and discharging, their performance may degrade if used in environments with temperatures higher than the appropriate temperature. If the heat is not controlled to the appropriate temperature, there is a risk of unexpected ignition or explosion. Furthermore, since battery modules consist of a structure in which such secondary batteries are densely housed inside a module housing, if any one of the secondary batteries experiences thermal runaway (heat propagation) and becomes a trigger cell, it can transfer to the lithium secondary battery, causing a chain reaction that can generate a large amount of vent gas, flames, and high-temperature particles containing electrode active material and aluminum particles. The vent gas, flames, and high-temperature sparks accumulate thermal energy not only in the battery module but also inside the battery pack, increasing the internal pressure and ultimately inducing structural collapse or explosion of the battery pack.

[0008] Therefore, structural improvements are needed to effectively disperse and efficiently release the pressure and thermal energy within the battery pack before the vent gas and flames generated in the first ignited battery module are transferred to adjacent battery modules and the entire battery pack. This will minimize the structural collapse of the battery pack and block the diffusion of thermal energy. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] This invention has been made in view of the above problems, and aims to provide a battery pack that effectively disperses and efficiently discharges pressure and thermal energy inside the battery pack before the vent gas and flames generated in the first ignited battery module are ejected and transferred to adjacent battery modules and battery packs, thereby delaying the structural collapse of the battery pack to the greatest extent possible and blocking the diffusion of thermal energy.

[0010] However, the technical problems that this invention aims to solve are not limited to those described above, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention below. [Means for solving the problem]

[0011] The battery pack according to the present invention may include a battery module, a pack tray that houses the battery module and is provided with an open upper end, a pack cover positioned on the upper end of the pack tray so as to seal the storage space in which the battery module is housed, and a variable coupling portion that connects the pack tray and the pack cover to each other and elastically connects the pack cover to the pack tray so as to expand variably in response to an increase in pressure when an event occurs.

[0012] The pack tray is provided with horizontal partition walls and vertical partition walls that divide the inside of the pack tray, and the variable coupling portion may include an expansion bolt, one end of which protrudes to the outside of the pack cover and the other end which passes through the pack cover and connects to at least one of the horizontal partition wall and the vertical partition wall, and an elastic member provided between the pack cover and the one end of the expansion bolt, which elastically biases the pack cover in one direction.

[0013] The variable coupling portion may further include a coupling housing provided on the pack cover that surrounds at least a portion of the elastic member and the expansion bolt.

[0014] The coupling housing may be a tubular body with guide holes formed in the longitudinal direction.

[0015] The elastic member may be a compression spring that provides resistance when the pack cover is compressed in the direction of the bolt head provided at one end of the expansion bolt.

[0016] The coupling housing may be formed integrally with the pack cover.

[0017] The elastic modulus of the elastic member may increase as it moves towards the central area of ​​the pack cover.

[0018] A gas outlet for discharging vent gas may be provided on one wall of the aforementioned pack tray.

[0019] The gas outlet is provided with a rupture membrane, and the rupture membrane may be provided with a discharge slit configured to rupture when a pressure exceeding the allowable pressure is applied.

[0020] The discharge slit may be provided with a cut in the form of a straight line or an I-shaped dotted line.

[0021] The pack cover may include a first pack cover adjacent to the battery module and a second pack cover positioned above the first pack cover at a predetermined distance from the first pack cover.

[0022] The variable coupling portion may include an expansion bolt having one end connected to a horizontal partition wall and a vertical partition wall; a first elastic member provided between the first pack cover and the second pack cover to separate the first pack cover and the second pack cover from each other; a second elastic member provided between the second pack cover and the expansion bolt to elastically bias the second pack cover in one direction; and a coupling housing provided in the second pack cover, with the second elastic member and the expansion bolt housed inside.

[0023] The pack cover includes a left pack cover provided on the left side with reference to the vertical partition wall and a right pack cover provided on the right side with reference to the vertical partition wall, and the variable coupling portion may be provided in a central area of the left pack cover and a central area of the right pack cover.

[0024] According to another aspect of the present invention, an automobile including the battery pack may be provided.

Effects of the Invention

[0025] According to one aspect of the present invention, before vent gas, flames, etc. generated by the first ignited battery module are ejected and transferred to adjacent battery modules and the battery pack, pressure and thermal energy are effectively dispersed inside the battery pack and efficiently discharged, thereby maximizing the delay of the structural collapse of the battery pack and blocking the diffusion of thermal energy.

[0026] In addition, the variable coupling portion can perform a kind of buffering function to buffer such impacts even in the case of a sudden change in the situation of an event, thereby preventing the structural collapse of the battery pack.

[0027] In addition, the stress concentration phenomenon at the bolt coupling site is reduced by the gas leakage pressure generated at the time of the occurrence of an event, and the maintenance cost of the battery pack can be reduced.

[0028] The effects of the present invention are not limited to the effects described above, and the effects not mentioned will be clearly understood by those having ordinary knowledge in the technical field to which the present invention pertains from the present specification and the attached drawings.

[0029] The following drawings attached to the present specification illustrate preferred embodiments of the present invention and serve to further understand the technical idea of the present invention together with the detailed description of the invention. Therefore, the present invention should not be construed as being limited only to the matters described in the drawings.

Brief Description of the Drawings

[0030] [Figure 1] This is a schematic perspective view showing a battery pack according to one embodiment of the present invention. [Figure 2] Figure 1 is an exploded perspective view of the main components of the battery pack. [Figure 3] This is a schematic top view of a battery pack according to one embodiment of the present invention. [Figure 4] Figure 3 shows a longitudinal cross-section of the battery pack along the A-A' incision line. [Figure 5] This is a longitudinal cross-sectional view of a variable coupling portion of a battery pack according to one embodiment of the present invention. [Figure 6] This is a partial perspective view of a gas outlet area according to one embodiment of the present invention. [Figure 7] This figure schematically shows the operating state of the variable coupling portion during the diffusion of vent gas and thermal energy in a battery pack according to one embodiment of the present invention. [Figure 8] This figure schematically shows the operating state of the variable coupling portion during the diffusion of vent gas and thermal energy in a battery pack according to one embodiment of the present invention. [Figure 9] This is a cross-sectional view of the gas outlet and the rupture membrane in a battery pack according to one embodiment of the present invention. [Figure 10] This figure shows a double pack cover and a variable coupling according to another embodiment of the present invention. [Figure 11] This is a top view of a battery pack provided with a left pack cover and a right pack cover, respectively, according to yet another embodiment of the present invention. [Figure 12] Figure 11 schematically shows the operating state of the variable coupling during the diffusion of vent gas and thermal energy in the battery pack. [Modes for carrying out the invention]

[0031] Preferred embodiments of the present invention will now be described in detail with reference to the attached drawings. Prior to this, terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner appropriate to the technical idea of ​​the present invention, in accordance with the principle that the inventor himself may appropriately define the concepts of terms in order to best describe the invention. Accordingly, it should be understood that the embodiments and configurations shown in the drawings described herein are merely the most preferred embodiments of the present invention and do not represent the entirety of the technical idea of ​​the present invention, and that there may be a variety of equivalents and modifications that can be substituted therein at the time of this application.

[0032] Figure 1 is a schematic perspective view of a battery pack according to one embodiment of the present invention, and Figure 2 is an exploded perspective view of the main components of the battery pack in Figure 1.

[0033] The battery pack 1 according to this embodiment may include a battery module 10, a pack tray 100 that houses the battery module 10 and is provided with an open upper end, a pack cover 200 positioned on top of the pack tray 100 so as to seal the storage space 220 in which the battery module 10 is housed, and a variable coupling portion 300 that connects the pack tray 100 and the pack cover 200 to each other and elastically connects the pack cover 200 to the pack tray 100 so as to expand the storage space 220 variably in response to the pressure increase of vent gas generated in the battery module 10 when an event occurs.

[0034] The battery module 10 includes a cell assembly formed by stacking battery cells, and a module case 12 for housing the cell assembly.

[0035] The pack tray 100 is a component for protecting the battery module 10 from external impacts, and may be made of a material with excellent mechanical rigidity. As shown in Figures 1 and 2, it is provided with a housing space 220 for housing at least one battery module 10 inside.

[0036] The pack tray 100 is provided with a horizontal partition wall 110 (in the Y-axis direction) and a vertical partition wall 120 (in the X-axis direction) that divide the inside of the pack tray 100. The height of the horizontal partition wall 110 and the vertical partition wall 120 is set to be relatively higher than the height of the battery module 10. As shown in Figure 2, the horizontal partition wall 110 and the vertical partition wall 120 protrude in the Z-axis direction above the upper surface of the battery module 10 housed in the pack tray 100, and the pack cover 200 covers them, providing a housing space 220 only the clearance gap between the battery module 10 and the pack cover 200. On the other hand, in this embodiment, a case is shown in which one horizontal partition wall 110 is provided along the Y-axis and one vertical partition wall 120 is provided along the X-axis inside the pack tray 100, and four battery modules 10 are housed inside. However, the scope of the present invention is not limited to the number of horizontal partition walls 110 and vertical partition walls 120 or the number of battery modules 10 housed inside in this embodiment.

[0037] The pack cover 200 is positioned on top of the pack tray 100 such that the storage space 220 in which the battery modules 10 are housed is sealed. In this embodiment, the pack cover 200 is provided to completely cover the four battery modules 10, and the pack cover 200 is made of aluminum or SUS material, and a slight curvature may be formed on the plate surface due to warping or sagging caused by changes in internal pressure.

[0038] The pack cover 200 is provided with a plurality of bolt connection holes 210. These bolt connection holes 210 are provided not only in the peripheral region of the pack cover 200, but also in the central region of the pack cover 200, corresponding to the horizontal partition wall 110 and the vertical partition wall 120. The size of the bolt connection holes 210 is provided to correspond to the size of the bolts to be connected. In this embodiment, if the size and length of the expansion bolts 310 are relatively larger than the connecting bolts 250, the bolt connection holes 210 in the central region may be provided to be larger and deeper than the bolt connection holes 210 in the peripheral region.

[0039] The pack cover 200 is bolted to the upper surface of the pack tray 100. The pack cover 200 is firmly fixed to the pack tray 100 by bolting it to the peripheral edge of the battery pack 1 with connecting bolts 250. However, the central area of ​​the pack cover 200 is not bolted to it with connecting bolts 250.

[0040] Figure 3 is a schematic top view of a battery pack according to one embodiment of the present invention, Figure 4 is a longitudinal cross-sectional view of the battery pack along the A-A' cutting line in Figure 3, Figure 5 is a longitudinal cross-sectional view of the variable coupling portion of the battery pack according to one embodiment of the present invention, and Figure 6 is a partial perspective view of the gas outlet 400 area according to one embodiment of the present invention.

[0041] If the entire area of ​​the pack tray 100 and the pack cover 200 is bolted together by the connecting bolts 250, the internal pressure accumulated when vent gas and flames generated in the initially ignited battery module 10 spread into the inside of the battery pack 1 cannot withstand it, and this could instead induce structural collapse or explosion of the battery pack 1. Therefore, in this embodiment, a variable connecting part 300 is disclosed.

[0042] The variable coupling portion 300 elastically connects the pack cover 200 to the pack tray 100 so as to allow expansion (or slight expansion) of the pack cover 200 by the variable coupling structure of the pack cover 200 to the pack tray 100, in order to respond to the increase in internal pressure and thermal energy due to the vent gas inside the battery pack 1.

[0043] The variable coupling portion 300 may include, as shown in Figures 3 to 5, an expansion bolt 310 having one end protruding to the outside of the pack cover 200 and the other end passing through the pack cover 200 and coupling to at least one of the horizontal partition wall 110 and the vertical partition wall 120; an elastic member 320 provided between the pack cover 200 and one end of the expansion bolt 310 to elastically bias the pack cover 200 in one direction; and a coupling housing 330 provided on the pack cover 200 and surrounding at least a portion of the elastic member 320 and the expansion bolt 310.

[0044] The expansion bolt 310 is provided to be relatively longer and thicker than the connecting bolt 250. This allows one end of the expansion bolt 310, i.e., the bolt head 311, to protrude to the outside of the pack cover 200, and the other end to pass through the pack cover 200 and connect to at least one of the horizontal partition wall 110 and the vertical partition wall 120. Referring to Figures 2 and 3, the expansion bolt 310 is located in three places along the horizontal partition wall 110, one of which is also provided in the center of the pack tray 100 where the horizontal partition wall 110 and the vertical partition wall 120 intersect each other.

[0045] The elastic member 320 is provided between the pack cover 200 and the bolt head 311 of the expansion bolt 310. One end of the elastic member 320 is supported by the bolt head 311 of the expansion bolt 310, and the other end is supported by the outer circumferential surface of the outer casing of the bolt connection hole 210 in the pack cover 200. The elastic member 320 elastically biases the pack cover 200 in one direction (the Z direction with reference to Figure 1). The elastic member 320 can be a compression spring that provides resistance when the pack cover 200 is compressed in the direction of the bolt head 311 provided at one end of the expansion bolt 310.

[0046] As a result, when an event occurs and the internal pressure of the pack cover 200 increases, the pack cover 200 expands along the expansion bolt 310, and the elastic member 320 acts as a resistive force, causing the pack cover 200 to enter a kind of warped state with a slight curvature, reaching an equilibrium state. This increases the internal storage space 220 of the battery pack 1, and delays the structural collapse of the battery pack 1.

[0047] Furthermore, in the event of a sudden change in circumstances, such as a rapid increase in vent gas leakage pressure or an explosive release of thermal energy, the elastic member 320 can perform a kind of buffering function to mitigate such impacts.

[0048] Furthermore, compared to the existing bolt connection between the pack tray 100 and the pack cover 200, the presence of an elastic member 320 in the expansion bolt 310 reduces stress concentration at the connection point of the expansion bolt 310 (such as the bolt head 311 or the horizontal partition wall 110 and vertical partition wall 120 of the pack tray 100).

[0049] Furthermore, the elastic modulus of the elastic member 320 may increase as it moves towards the central area of ​​the pack cover 200. Referring mainly to Figures 3 and 4, the elastic modulus of the elastic member 320 of the variable coupling portion 300 located in the center of the pack cover 200 may be set higher than that of the elastic member 320 of the variable coupling portion 300 on the left side (located between the first and second areas).

[0050] Therefore, when an event occurs in the first region, the expansion gap d, which is the gap between the pack tray 100 and the pack cover, may be opened (expanded) more at the variable joint 300 to the left of the central point. Alternatively, no expansion gap d may occur at the central variable joint 300. In such a case, the containment spaces 220 of the first and second regions are interconnected and the containment spaces 220 expand, while the first and third regions remain separated, allowing for local expansion of the containment spaces 220.

[0051] On the other hand, if an expansion gap d is generated in the variable coupling portion 300 in the center of the pack cover 200, depending on the pressure and thermal energy inside the battery pack 1, the entire storage space 220 can be expanded not only to the first and second regions, but also to the third and fourth regions.

[0052] The coupling housing 330 is provided on the pack cover 200, and the coupling housing 330 may be a tubular body with guide holes formed in the longitudinal direction. Here, the thickness of the wall constituting the tubular body may be substantially the same as the thickness of the pack cover 200. In this embodiment, the coupling housing 330 may be formed integrally with the pack cover 200, but alternatively, the coupling housing 330 may be manufactured separately and then attached to the upper surface of the pack cover 200 by welding or bolting.

[0053] The coupling housing 330 is a portion that surrounds at least a part of the elastic member 320 and the expansion bolt 310. That is, the expansion bolt 310 can be partially housed in the guide hole 332 of the coupling housing 330, and the elastic member 320 can be housed while still fitted onto the expansion bolt 310. This allows the elastic member 320 to be compressed in the guide hole 332 or to move smoothly, while the elastic member 320 is housed inside the coupling housing 330, thus protecting the elastic member 320 from contact with external foreign matter and dust, and preventing such foreign matter from entering the battery pack 1.

[0054] Referring to Figure 6, a gas outlet 400 from which the vent gas is discharged may be provided on one wall of the pack tray 100. A ring member 420 is provided on the outer circumferential surface of such a gas outlet 400, and a rupture membrane 410 is provided connected to the ring member 420. The ring member 420 is attached to the outer surface of the pack tray 100 by bolts 430 to withstand the internal pressure of the battery pack 1.

[0055] The rupture membrane 410 may be provided with a discharge slit 411 configured to rupture when a pressure exceeding the allowable pressure is applied. The discharge slit 411 may be provided in the form of a straight line or an I-shaped dotted line. For example, when a pressure exceeding the allowable pressure designed for the ignited battery module 10 is applied, the discharge slit 411 ruptures, allowing vent gas and thermal energy to be released.

[0056] For example, in Figure 3, when an event occurs in the battery module 10 in the first region, the internal pressure rises, causing the variable coupling part 300 on the left side to operate and communicate with the housing space 220 in the second region. Subsequently, the discharge slit 411 ruptures, and vent gas and thermal energy are discharged from the gas outlet 400 on the left side of the battery pack 1.

[0057] With this implementation configuration, before the vent gas and flames generated in the first ignited battery module 10 are ejected and transferred to the adjacent battery module 10 and battery pack 1, the pressure and thermal energy can be effectively dispersed and efficiently discharged inside the battery pack 1, thereby maximally delaying the structural collapse of the battery pack 1 and blocking the diffusion of thermal energy.

[0058] Furthermore, with this configuration, in the event of a sudden change in the event conditions, such as a sudden increase in the internal pressure of the battery pack 1 or an explosive release of thermal energy, the variable coupling section 300 acts as a buffer to absorb such shocks, thereby preventing the structural collapse of the battery pack 1.

[0059] Furthermore, compared to conventional bolt connections between the pack tray 100 and the pack cover 200, the inclusion of an elastic member 320 in the expansion bolt 310 reduces stress concentration at the connection points of the expansion bolt 310 (such as the bolt head 311 or the horizontal and vertical partition walls 110 and 120 of the pack tray 100), thereby reducing the maintenance costs of the battery pack 1 structure.

[0060] Figures 7 and 8 schematically show the operating state of the variable coupling when vent gas and thermal energy are diffused in a battery pack according to one embodiment of the present invention, and Figure 9 shows the cross-section of the gas outlet and rupture membrane in a battery pack according to one embodiment of the present invention.

[0061] The discharge process by which the vent gas is easily discharged to the outside according to this embodiment will be described in detail below with reference to Figures 1 to 7.

[0062] First, when an event occurs in the battery module 10 on the left side of Figure 7, thermal energy such as vent gas, flames, electrode active material, and high-temperature particles including aluminum particles are ejected.

[0063] As a result, the internal pressure of the containment space 220 increases, and the variable coupling part 300 operates due to an internal pressure exceeding the allowable pressure. That is, the internal pressure becomes greater than the resistance force of the elastic member 320, and the pack cover 200 expands while the elastic member 320 contracts. At this time, the rise of the pack cover 200 and the coupling housing 330 has the effect of causing the bolt head 311 of the expansion bolt 310 to move downward within the coupling housing 330.

[0064] As a result, vent gas and other substances are ejected only in the containment space 220 in the first region of Figure 3, causing the internal pressure to rise. The expansion gap d between the pack cover 200 and the lateral partition wall 110 locally expands the containment space 220 for vent gas and other substances into the second region. This effectively distributes pressure and thermal energy inside the battery pack 1, thereby delaying the structural collapse of the battery pack 1 to the greatest extent possible.

[0065] Next, vent gas and other substances are discharged through the gas outlet 400 shown in Figure 9. The vent gas and thermal energy generated in the first region of Figure 3 diffuse into the second region, and if the internal pressure continues to increase and exceeds the allowable pressure, the discharge slit 411 ruptures, and the vent gas and other substances are discharged. This effectively disperses and efficiently discharges the internal pressure and thermal energy of the battery pack 1, thereby delaying the structural collapse of the battery pack 1.

[0066] Here, the operation of the variable coupling part 300 at the center of the battery pack 1 may be given priority over the discharge process. For example, the elastic modulus at the center can be adjusted taking into account the design pressure of the discharge slit 411, and after the variable coupling part 300 operates in the first and second regions, if the internal pressure exceeds a predetermined level, the variable coupling part 300 at the center may operate before the discharge slit 411 as shown in Figure 8. In such a case, when an event occurs in the first region in Figure 3, the containment space 220 is expanded to the second, third, and fourth regions, and then, when the internal pressure continues to increase, vent gas and the like may be discharged through the discharge slit 411.

[0067] This operational configuration effectively disperses the vent gas and flames generated in the first ignited battery module 10 into the battery pack 1 before they are transferred to adjacent battery modules 10 and battery pack 1, efficiently releasing the pressure and thermal energy. This minimizes the structural collapse of the battery pack 1 and prevents the diffusion of thermal energy.

[0068] Next, other embodiments of the battery pack 1 of the present invention will be briefly described with reference to Figures 10 to 12.

[0069] Figure 10 shows a double pack cover and variable coupling according to another embodiment of the present invention, Figure 11 is a top view of a battery pack provided with a left pack cover and a right pack cover, respectively, according to yet another embodiment of the present invention, and Figure 12 is a schematic diagram showing the operating state of the variable coupling during the diffusion of vent gas and thermal energy in the battery pack of Figure 11.

[0070] In the drawings, the same part number indicates the same part, redundant explanations for the same part are omitted, and the explanation focuses on the differences from the previously described embodiment.

[0071] In another embodiment of the present invention, the battery pack is provided with a double-layered pack cover 200 that is spaced apart at a predetermined interval, compared to the embodiment described above. That is, as shown in Figure 10, the pack cover 200 may consist of a first pack cover 230 adjacent to the battery module 10 and a second pack cover 240 positioned above the first pack cover 230 at a predetermined distance from the first pack cover 230.

[0072] The variable coupling portion 300A may include an expansion bolt 310, one end of which is coupled to the horizontal partition wall 110 and the vertical partition wall 120; a first elastic member 321 provided between the first pack cover 230 and the second pack cover 240 to separate the first pack cover 230 and the second pack cover 240 from each other; a second elastic member 322 provided between the second pack cover 240 and the expansion bolt 310 to elastically bias the second pack cover 240 in one direction; and a coupling housing 331 provided on the second pack cover 240, with the second elastic member 322 and the expansion bolt 310 housed inside.

[0073] The first pack cover 230 and the second pack cover 240 are provided with a predetermined distance S between them, and a first elastic member 321 is provided between them to separate the first pack cover 230 and the second pack cover 240 from each other. The second elastic member 322 is provided between the second pack cover 240 and the expansion bolt 310, and plays a role in elastically biasing the second pack cover 240 in one direction.

[0074] The two-tiered pack covers 230 and 240 are provided, and the first elastic member 321 and the second elastic member 322 form a two-tiered buffer structure. In the event of a sudden change in the situation, such as a sudden increase in vent gas leakage pressure or an explosive ejection of thermal energy, the variable coupling section 300 can prevent structural collapse of the battery pack by improving its shock-absorbing function through the two-tiered buffer structure.

[0075] Furthermore, by effectively dispersing and efficiently releasing the pressure and thermal energy inside the battery pack before the vent gas and flames generated in the initially ignited battery module 10 are ejected and transferred to adjacent battery modules 10 and the battery pack, the structural collapse of the battery pack can be delayed to the greatest extent possible, and the diffusion of thermal energy can be blocked.

[0076] In yet another embodiment of the present invention, the battery pack is configured such that, compared to the first embodiment, the pack cover 200 is separated into a left pack cover 260 and a right pack cover 270, and the configuration of the variable coupling portion 300 at the center of the battery pack is omitted.

[0077] As a result, as shown in Figure 11, when an event occurs in the first region, the left variable coupling part 300B operates, causing the left pack cover 200 to expand. When the pressure exceeds the allowable pressure, it becomes possible to discharge the gas from the left gas outlet 400. In this case, compared to the first embodiment, there is a difference in that the pack cover 200 in the first embodiment is completely separated into the left pack cover 260 and the right pack cover 270, so the expansion of the containment space 220 from the first and second regions to the third region does not occur.

[0078] On the other hand, although not shown in the figures, the battery pack 1 according to the present invention may further include various devices for controlling the charging and discharging of the battery module 10, such as a BMS (Battery Management System), a current sensor, a fuse, and the like.

[0079] The battery pack 1 according to the present invention is applicable to automobiles such as electric vehicles and hybrid vehicles. That is, an automobile according to the present invention may include the battery pack 1 according to the present invention. The battery pack 1 may be installed in the vehicle body frame under the seats or in the trunk space, and when installed in the vehicle, the arrangement order of the battery pack may be reversed as needed.

[0080] In this specification, terms indicating direction such as up, down, left, right, front, and back are used, but these terms are for the sake of convenience of explanation only, and it is obvious to those skilled in the art that the direction can change depending on the position of the object in question, the position of the observer, etc.

[0081] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it goes without saying that various modifications and variations are possible within the equivalent scope of the technical concept and claims of the present invention by persons with ordinary skill in the art to which the present invention pertains. [Explanation of symbols]

[0082] 1 Battery Pack 10 Battery Modules 12 Module Cases 100 pack tray 110 Wall 120 Wall 200 Pack Cover 210 bolt connection holes 220 storage space 230, 240 pack cover 250 connecting bolts 260 Left side pack cover 270 Right-side pack cover 300, 300A, 300B Variable coupling section 310 Expansion bolt 311 Bolt Head 320, 321, 322 Elastic members 330, 331 Combined Housing 332 Guide Hall 400 Gas Outlets 410 Rupture membrane 411 Discharge slit 420 Ring component 430 volts

Claims

1. Battery module and A pack tray is provided that houses the aforementioned battery module inside and has an open top end, A pack cover is positioned at the upper end of the pack tray such that the storage space in which the battery module is housed is sealed, A variable coupling portion connects the pack tray and the pack cover to each other, and elastically connects the pack cover to the pack tray so that the storage space expands variably in response to the pressure increase when an event occurs, Includes, The aforementioned pack cover is The battery module and the first pack cover adjacent to it, A flat plate-shaped second pack cover is positioned on top of the first pack cover so as to be separated from the first pack cover by a predetermined distance, Includes, The aforementioned variable coupling portion is An expansion bolt having one end protruding to the outside of the second pack cover and the other end passing through the second pack cover and the first pack cover to connect to the pack tray, A first elastic member is provided between the first pack cover and the second pack cover, and separates the first pack cover and the second pack cover from each other. A second elastic member is provided between the second pack cover and the one end of the expansion bolt, and elastically biases the second pack cover in one direction, A battery pack characterized by including the following.

2. The pack tray is provided with horizontal partition walls and vertical partition walls that divide the inside of the pack tray. The battery pack according to claim 1, characterized in that the other end of the expansion bolt is connected to at least one of the horizontal partition wall and the vertical partition wall.

3. The aforementioned variable coupling portion is The battery pack according to claim 2, further comprising a coupling housing provided on the second pack cover and surrounding at least a portion of the second elastic member and the expansion bolt.

4. The battery pack according to claim 3, characterized in that the coupling housing is a tubular body with guide holes formed in the longitudinal direction.

5. The battery pack according to claim 3, characterized in that the coupling housing is integrally formed with the second pack cover.

6. The battery pack according to claim 2, characterized in that the second elastic member is a compression spring that provides resistance when the second pack cover is compressed in the direction of the bolt head provided at one end of the expansion bolt.

7. The battery pack according to claim 2, characterized in that the elastic moduli of the first elastic member and the second elastic member increase as they move toward the central area of ​​the pack cover.

8. The battery pack according to claim 5, characterized in that a gas outlet for discharging vent gas is provided on one wall of the pack tray.

9. The aforementioned gas outlet is provided with a rupture membrane. The battery pack according to claim 8, characterized in that the rupture membrane is provided with an exhaust slit configured to rupture when a pressure exceeding an allowable pressure is applied.

10. The battery pack according to claim 9, characterized in that the discharge slit is provided with a cut in the form of a straight line or an I-shaped dotted line.

11. The horizontal partition wall extends in the longitudinal direction of the pack tray, and the vertical partition wall extends in the short direction of the pack tray, The aforementioned pack cover is A left-side pack cover is provided on the left side relative to the aforementioned vertical partition wall, This includes a right-side pack cover provided on the right side with respect to the aforementioned vertical partition wall, The battery pack according to claim 2, characterized in that the variable coupling portion includes the expansion bolt that connects the central area of ​​the left pack cover and the lateral partition wall, and the expansion bolt that connects the central area of ​​the right pack cover and the lateral partition wall.

12. An automobile characterized by including a battery pack according to any one of claims 1 to 11.

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