Battery pack with a variable coupling part that prevents 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 semi-permanent battery that can convert electrical energy into chemical energy and repeat charging and discharging is called a secondary battery, as distinguished from a disposable primary battery.

[0004] Examples of secondary batteries include lithium secondary batteries, nickel-cadmium (Ni-Cd) batteries, lead-acid batteries, nickel-metal hydride (Ni-MH) batteries, air zinc batteries, and alkaline manganese batteries. Among these, lead-acid batteries and lithium secondary batteries can be said to be the most actively commercialized secondary batteries.

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

[0006] Currently, the operating voltage of a single lithium secondary battery cell is around 2.5V to 4.5V. Therefore, in order to apply a secondary battery as an energy source for an electric vehicle, a battery module is configured by connecting a plurality of lithium-ion battery cells in series and / or in parallel, and further, a battery pack is configured by connecting the battery modules in series and / or in parallel.

[0007] On the other hand, since a secondary battery involves a chemical reaction during charging and discharging, its performance may deteriorate when used in an environment with a temperature higher than the appropriate temperature, and there is a possibility of unexpected ignition or explosion when heat is not controlled to the appropriate temperature. In addition, since the battery module has a structure in which such secondary batteries are intensively housed inside the module housing, if any one secondary battery undergoes thermal runaway (heat propagation) and becomes a trigger cell, it will be transferred to the lithium secondary battery, and a chain reaction may occur, generating a large amount of vent gas, flame, and high-temperature particles including electrode active materials and aluminum particles. The vent gas, flame, and high-temperature sparks accumulate thermal energy inside not only the battery module but also the battery pack, increasing the internal pressure, and ultimately inducing the structural collapse or explosion of the battery pack.

[0008] Therefore, before the vent gas, flame, etc. generated in the first ignited battery module are ejected and transferred to the adjacent battery module and the entire battery pack, it is required to improve the structure so that the pressure and thermal energy inside the battery pack are effectively dispersed and efficiently discharged, thereby delaying the structural collapse of the battery pack to the maximum extent and blocking the diffusion of thermal energy. Summary of the Invention Problems to be Solved by the Invention

[0009] The present invention has been made in view of the above problems, and before the vent gas and flames generated in the first ignited battery module are ejected and transferred to adjacent battery modules and battery packs, the pressure and thermal energy are effectively dispersed inside the battery pack, and by efficiently discharging them, the structural collapse of the battery pack is maximally delayed, and an object of the present invention is to provide a battery pack capable of blocking the diffusion of thermal energy.

[0010] However, the technical problems to be solved by the present invention are not limited to the above problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description of the invention.

Means for Solving the Problems

[0011] 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 with an open upper end, a pack cover that is disposed at the upper end of the pack tray so that the accommodation space in which the battery module is housed is sealed, and a variable coupling portion that 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, by connecting the pack tray and the pack cover to each other.

[0012] The pack tray is provided with a horizontal partition wall and a vertical partition wall that partition the inside of the pack tray, and the variable coupling portion may include an expansion bolt having one end protruding outside the pack cover and the other end passing through the pack cover and coupling 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 to elastically bias the pack cover in one direction.

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

[0014] The coupling housing may be a tubular body in which a guide hole is 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 integrally formed with the pack cover.

[0017] The elastic coefficient of the elastic member may increase as it progresses toward the central region of the pack cover.

[0018] A gas outlet through which vent gas is discharged may be provided on one wall of the pack tray.

[0019] A rupture membrane may be provided at the gas outlet, and the rupture membrane may be provided with a discharge slit configured to rupture when a pressure equal to or higher than the allowable pressure is applied.

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

[0021] The pack cover may include a first pack cover adjacent to the battery module and a second pack cover disposed above the first pack cover so as to be spaced apart from the first pack cover by a predetermined interval.

[0022] The variable coupling portion may include an expansion bolt having one end coupled 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 and separating 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 and elastically biasing the second pack cover in one direction, and a coupling housing provided on the second pack cover and accommodating the second elastic member and the expansion bolt therein.

[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 part may be provided in the central area of the left pack cover and the 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.

Advantages of the Invention

[0025] According to one aspect of the present invention, before the vent gas and flames generated by the first ignited battery module are ejected and transferred to adjacent battery modules and the battery pack, the pressure and thermal energy inside the battery pack are effectively dispersed and efficiently discharged, so that the structural collapse of the battery pack is maximally delayed and the diffusion of thermal energy can be blocked.

[0026] In addition, the variable coupling part performs a kind of buffering function of buffering such impacts even in the case of a sudden change in the situation of the event, thereby preventing the structural collapse of the battery pack.

[0027] In addition, the stress concentration phenomenon at the bolt coupling part is reduced by the gas leakage pressure generated at the time of the occurrence of the 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 accompanying drawings.

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

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0031] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in this specification and claims should not be construed as being limited to their ordinary or dictionary meanings. The inventor himself must interpret them in accordance with the meaning and concept corresponding to the technical idea of the present invention in accordance with the principle that he can appropriately define the concept of the terms in order to explain the invention in the best way. Therefore, it must be understood that the embodiments described in this specification and the configurations shown in the drawings are only one of the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, there may be various equivalents and modifications that can replace them at the time of this application.

[0032] FIG. 1 is a perspective view schematically showing a battery pack according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the main components of the battery pack of FIG. 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 therein and is provided with an open upper end, a pack cover 200 that is disposed on the upper part of the pack tray 100 so as to seal the accommodation space 220 in which the battery module 10 is accommodated, and a variable coupling portion 300 that elastically couples the pack tray 100 and the pack cover 200 to each other so that the accommodation space 220 is variably expanded in response to an increase in the pressure of the 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 the like, and may be provided with a material having excellent mechanical rigidity. As shown in FIGS. 1 and 2, a storage space 220 for accommodating at least one battery module 10 is provided inside.

[0036] The pack tray 100 is provided with a horizontal partition wall 110 (Y-axis direction) and a vertical partition wall 120 (X-axis direction) for partitioning the inside of the pack tray 100. The heights of the horizontal partition wall 110 and the vertical partition wall 120 are provided relatively higher than the height of the battery module 10. As shown in FIG. 2, the horizontal partition wall 110 and the vertical partition wall 120 protrude in the Z-axis direction from the upper surface of the battery module 10 accommodated in the pack tray 100, and the pack cover 200 is covered so that a storage space 220 is provided only in the separation gap between the battery module 10 and the pack cover 200. On the other hand, in the present embodiment, one horizontal partition wall 110 along the Y-axis and one vertical partition wall 120 along the X-axis are provided inside the pack tray 100, and the case where four battery modules 10 are accommodated is shown. However, the scope of the present invention is not limited to the number of the horizontal partition wall 110 and the vertical partition wall 120 in this embodiment or the number of the battery modules 10 to be accommodated.

[0037] The pack cover 200 is disposed on the upper part of the pack tray 100 so that the storage space 220 in which the battery module 10 is accommodated is sealed. The pack cover 200 in the present embodiment is provided so as to completely cover four battery modules 10. The pack cover 200 is made of an aluminum material or a SUS material, and a minute curvature can be formed on the plate surface due to warping or sagging caused by a change in internal pressure.

[0038] The pack cover 200 is provided with a plurality of bolt coupling holes 210. The bolt coupling 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 coupling holes 210 is provided to correspond to the size of the bolts to be coupled. When the size and length of the extension bolts 310 are relatively larger than the coupling bolts 250 in this embodiment, the bolt coupling holes 210 in the central region can be provided larger and deeper than the bolt coupling holes 210 in the peripheral portion.

[0039] The pack cover 200 is bolt-coupled to the upper surface of the pack tray 100. The pack cover 200 is firmly fixed to the pack tray 100 by being bolt-coupled to the peripheral portion of the battery pack 1 with the coupling bolts 250. Here, the central region of the pack cover 200 is not bolt-coupled with the coupling bolts 250.

[0040] FIG. 3 is a top view schematically showing a battery pack according to an embodiment of the present invention, FIG. 4 is a longitudinal sectional view of the battery pack taken along the cut line A-A' of FIG. 3, FIG. 5 is a longitudinal sectional view of a variable coupling portion of the battery pack according to an embodiment of the present invention, and FIG. 6 is a partial perspective view of the gas outlet 400 region according to an embodiment of the present invention.

[0041] If bolt coupling is performed by the coupling bolts 250 over the entire regions of the pack tray 100 and the pack cover 200, when an event occurs in which vent gas, flames, etc. generated in the first ignited battery module 10 diffuse into the battery pack 1, the internal pressure accumulated at that time cannot be withstood, and instead, it may induce the structural collapse or explosion of the battery pack 1. Therefore, in this embodiment, a variable coupling portion 300 is disclosed.

[0042] The variable coupling portion 300 elastically couples the pack cover 200 to the pack tray 100 by a variable coupling structure of the pack cover 200 so as to allow expansion (or minute expansion) of the pack cover 200 with respect to the pack tray 100 in response to an increase in internal pressure due to vent gas inside the battery pack 1 or an increase in thermal energy.

[0043] As shown in FIGS. 3 to 5, the variable coupling portion 300 may include an expansion bolt 310 having one end protruding outside 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 to surround at least a part of the elastic member 320 and the expansion bolt 310.

[0044] The expansion bolt 310 is provided in a size that is relatively longer and thicker than the coupling bolt 250. Thereby, one end of the expansion bolt 310, i.e., the bolt head 311, protrudes outside the pack cover 200, and the other end may pass through the pack cover 200 and couple to at least one of the horizontal partition wall 110 and the vertical partition wall 120. Referring to FIGS. 2 and 3, the expansion bolt 310 is located at three positions along the horizontal partition wall 110, and one of them is also provided at 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 peripheral surface of the outer contour of the bolt coupling hole 210 in the pack cover 200. And the elastic member 320 elastically biases the pack cover 200 in one direction (Z direction with reference to FIG. 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] Thus, when an event occurs and the internal pressure of the pack cover 200 rises, when the pack cover 200 expands along the expansion bolt 310, the elastic member 320 acts as a resistance force, and the pack cover 200 assumes a warped state with a minute curvature to reach an equilibrium state. As a result, the accommodation space 220 inside the battery pack 1 increases, and it is possible to delay the structural collapse of the battery pack 1.

[0047] Also, in the case of a sudden change in the situation of an event, for example, when the leakage pressure of the vent gas suddenly rises or thermal energy erupts explosively, the elastic member 320 can function as a kind of shock absorber to buffer such an impact.

[0048] Also, compared with the bolt connection between the existing pack tray 100 and the pack cover 200, since the elastic member 320 is interposed in the expansion bolt 310, stress concentration on the connection part of the expansion bolt 310 (such as the bolt head 311 or the horizontal partition wall 110 and the vertical partition wall 120 of the pack tray 100) can be reduced.

[0049] And the elastic coefficient of the elastic member 320 can increase as it progresses toward the central area of the pack cover 200. Mainly referring to FIGS. 3 and 4, the elastic coefficient of the elastic member 320 of the variable coupling part 300 arranged at the center of the pack cover 200 can be set higher than the elastic coefficient of the elastic member 320 of the variable coupling part 300 arranged on the left side (arranged between the first region and the second region).

[0050] Therefore, when an event occurs in the first region, the expansion gap d, which is the gap between the packet tray 100 and the packet cover, can be opened (expanded) more at the variable coupling portion 300 on the left side of the central point. Or, no expansion gap d may occur at the central variable coupling portion 300. In such a case, the accommodation space 220 can be locally expanded such that the first region and the second region communicate with each other and the accommodation space 220 is expanded, and the first region and the third region are in a separated state.

[0051] On the other hand, when an expansion gap d also occurs at the central variable coupling portion 300 of the packet cover 200 according to the pressure and thermal energy level inside the battery pack 1, not only the first region and the second region but also the third region and the fourth region can be comprehensively expanded in the accommodation space 220.

[0052] The coupling housing 330 is provided on the packet cover 200, and the coupling housing 330 can be a tubular body in which a guide hole is formed in the longitudinal direction. Here, the thickness of the wall body constituting the tubular body can be substantially the same as the thickness of the packet cover 200. In this embodiment, the coupling housing 330 can be integrally formed with the packet cover 200. However, differently, after the coupling housing 330 is separately manufactured, it may be manufactured by welding or bolting or the like to the upper surface of the packet cover 200.

[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 is partially accommodated in the guide hole 332 of the coupling housing 330, and the elastic member 320 can be accommodated while being fitted to the expansion bolt 310. As a result, while the elastic member 320 can be compressed in the guide hole 332 or the stretching movement can be smoothed, since the elastic member 320 is accommodated inside the coupling housing 330, it can function to protect the elastic member 320 by blocking contact with external foreign matters and dust, etc., and it is also possible to prevent such foreign matters from flowing into the battery pack 1.

[0054] As shown in FIG. 6, a gas outlet 400 through 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 peripheral surface of such a gas outlet 400, and a rupture film 410 connected to the ring member 420 is provided. The ring member 420 is provided to be coupled 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 film 410 may be provided with a discharge slit 411 configured to break when a pressure equal to or higher than the allowable pressure is applied. The discharge slit 411 may be provided in the form of a dotted line with a cut in a straight line or I - shape. For example, when a pressure equal to or higher than the allowable pressure designed for the fired battery module 10 is applied, the vent gas and thermal energy can be discharged by the discharge slit 411 breaking.

[0056] For example, in FIG. 3, when an event occurs in the battery module 10 in the first region, the left - hand variable coupling portion 300 operates due to the increase in internal pressure to communicate with the accommodation space 220 in the second region, and then, when the discharge slit 411 breaks, the vent gas and thermal energy are discharged from the gas outlet 400 on the left side of the battery pack 1.

[0057] According to such an implementation configuration, before the vent gas and flame generated by 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 inside the battery pack 1 are effectively dispersed and efficiently discharged, thereby maximizing the delay of the structural collapse of the battery pack 1 and blocking the diffusion of thermal energy.

[0058] Also, according to such an implementation configuration, in the case of a sudden change in the situation of an event, for example, when the internal pressure of the battery pack 1 rapidly rises or thermal energy erupts explosively, the variable coupling part 300 can perform a kind of buffering function to buffer such an impact, thereby preventing the structural collapse of the battery pack 1.

[0059] Moreover, compared with the bolt connection between the conventional pack tray 100 and the pack cover 200, since the elastic member 320 is fitted on the expansion bolt 310, the stress concentration on the connection part 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) can be reduced, and the maintenance cost of the structure of the battery pack 1 can be saved.

[0060] FIG. 7 and FIG. 8 are diagrams schematically showing the operating state of the variable coupling part when vent gas and thermal energy diffuse in a battery pack according to an embodiment of the present invention, and FIG. 9 is a cross-section of the gas outlet and rupture film in a battery pack according to an embodiment of the present invention.

[0061] Hereinafter, the discharge process in which the vent gas is easily discharged to the outside according to this embodiment will be described in detail with reference to FIGS. 1 to 7.

[0062] First, when an event occurs in the left battery module 10 in FIG. 7, thermal energy such as vent gas, flame, and high-temperature particles including electrode active material and aluminum particles is ejected.

[0063] Then, the internal pressure of the accommodation space 220 rises, and the variable coupling part 300 operates due to the internal pressure equal to or higher than the allowable pressure. That is, the internal pressure becomes greater than the resistance force of the elastic member 320, and the elastic member 320 contracts while the pack cover 200 expands. At this time, as the pack cover 200 and the coupling housing 330 rise, an effect is generated such that the bolt head 311 of the expansion bolt 310 moves downward within the coupling housing 330.

[0064] As a result, only the accommodation space 220 in the first region of the conventional FIG. 3 vents gas or the like, causing the internal pressure to rise. Due to the expansion gap d between the pack cover 200 and the horizontal partition wall 110, the accommodation space 220 for vent gas or the like is locally expanded to the second region. As a result, by effectively dispersing the pressure and thermal energy inside the battery pack 1, it becomes possible to maximally delay the structural collapse of the battery pack 1.

[0065] Next, the vent gas or the like is discharged through the gas outlet 400 shown in FIG. 9. When the vent gas and thermal energy generated in the first region of FIG. 3 diffuse to the second region and the internal pressure continues to increase and exceeds the allowable pressure, the discharge slit 411 breaks and the vent gas or the like is discharged. By effectively dispersing and efficiently discharging the pressure and thermal energy inside the battery pack 1, it becomes possible to delay the structural collapse of the battery pack 1.

[0066] Here, the operation of the variable coupling part 300 at the central point of the battery pack 1 may be prioritized over the discharge process. For example, the elastic coefficient at the central point is adjusted in consideration of the design pressure of the discharge slit 411. After the variable coupling part 300 operates in the first region and the second region, when the internal pressure is above a predetermined value, the variable coupling part 300 at the central point can operate as shown in FIG. 8 prior to the discharge slit 411. In such a case, when an event occurs in the first region of FIG. 3, after the accommodation space 220 expands to the second region, the third region, and the fourth region, when the internal pressure continues to increase, the vent gas or the like can be discharged through the discharge slit 411.

[0067] With such an operation configuration, the vent gas, flame, etc. generated in the first-fired battery module 10 are ejected, and the pressure and thermal energy are effectively dispersed and efficiently discharged inside the battery pack 1 before being transferred to the adjacent battery module 10 and the battery pack 1, thereby delaying the structural collapse of the battery pack 1 to the maximum extent and blocking the diffusion of thermal energy.

[0068] Subsequently, with reference to FIGS. 10 to 12, another embodiment of the battery pack 1 of the present invention will be briefly described.

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

[0070] In the drawings, the same member numbers indicate the same members, and duplicate descriptions of the same members are omitted. The description will focus on the differences from the above-described embodiments.

[0071] The battery pack according to another embodiment of the present invention, compared with the above-described embodiment, the pack cover 200 is provided as a double structure separated at a predetermined interval. That is, as shown in FIG. 10, the pack cover 200 may be composed of a first pack cover 230 adjacent to the battery module 10 and a second pack cover 240 disposed above the first pack cover 230 so as to be separated from the first pack cover 230 by a predetermined interval.

[0072] And the variable coupling portion 300A may include an extension bolt 310 having one end 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 and separating 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 extension bolt 310 and elastically biasing the second pack cover 240 in one direction, and a coupling housing 331 provided on the second pack cover 240 and housing the second elastic member 322 and the extension bolt 310 therein.

[0073] The first pack cover 230 and the second pack cover 240 are provided with a predetermined interval S therebetween, and a first elastic member 321 that separates the first pack cover 230 and the second pack cover 240 from each other is provided therebetween. And the second elastic member 322 is provided between the second pack cover 240 and the extension bolt 310 and serves to elastically bias the second pack cover 240 in one direction.

[0074] The two-stage pack covers 230 and 240 are provided, and by providing a two-stage buffer structure by the first elastic member 321 and the second elastic member 322, in the case of a sudden change in the situation of an event, for example, when the leakage pressure of the vent gas suddenly rises or the thermal energy erupts explosively, the variable coupling portion 300 can prevent the structural collapse of the battery pack by improving the buffer function of buffering the impact by the two-stage buffer structure.

[0075] Also, before the vent gas, flame, etc. generated in the first-fired battery module 10 are ejected and transferred to the adjacent battery module 10 and the battery pack, by effectively dispersing and efficiently discharging the pressure and thermal energy inside the battery pack, the structural collapse of the battery pack can be maximally delayed and the diffusion of the thermal energy can be blocked.

[0076] According to still another embodiment of the present invention, compared with the first embodiment, the pack cover 200 of the battery pack is configured to be separated into a left pack cover 260 and a right pack cover 270, and the configuration of the variable coupling portion 300 at the central point of the battery pack is omitted.

[0077] As a result, as shown in FIG. 11, when an event occurs in the first region, the left variable coupling portion 300B operates to expand the left pack cover 200, and when the pressure exceeds the allowable pressure, it can be discharged from the left gas outlet 400. At this time, compared with the first embodiment, since the pack cover 200 of the first embodiment is completely separated into the left pack cover 260 and the right pack cover 270, there is a difference that the expansion of the accommodation space 220 from the first region and the second region to the third region does not occur.

[0078] On the other hand, although not shown in the drawings, 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, the automobile according to the present invention may include the battery pack 1 according to the present invention. The battery pack 1 may be provided in the vehicle body frame under the seat of the vehicle or in the trunk space, and when installed in the vehicle, the arrangement order of the battery packs may be arranged in reverse as necessary.

[0080] In addition, in this specification, terms indicating directions such as up, down, left, right, front, and rear are used, but such terms are only for convenience of explanation and are obvious to those skilled in the art that they may change depending on the position of the object to be observed and the position of the observer.

[0081] As described above, the present invention has been explained by limited embodiments and drawings. However, the present invention is not limited thereto, and various modifications and variations can be made within the equivalent scope of the technical idea and claims of the present invention by those having ordinary knowledge in the technical field to which the present invention pertains.

Explanation of Reference Numerals

[0082] 1 Battery pack 10 Battery modules 12 Module case 100 Pack tray 110 Wall 120 Wall 200 Pack cover 210 Bolt coupling hole 220 Accommodation space 230, 240 Pack covers 250 Coupling bolt 260 Left pack cover 270 Right pack cover 300, 300A, 300B Variable coupling part 310 Extension bolt 311 Bolt head 320, 321, 322 Elastic members 330, 331 Coupling housings 332 Guide hole 400 Gas outlet 410 Rupture membrane 411 Discharge slit 420 Ring member 430 Bolt

Claims

1. A battery module, A pack tray that houses the battery module inside and is provided with an open upper end, A pack cover disposed at the upper end of the pack tray so that the accommodation space in which the battery module is housed is sealed, 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. A battery pack, characterized in that it comprises.

2. The pack tray is provided with a horizontal partition wall and a vertical partition wall that partition the inside of the pack tray, The variable coupling portion is, An expansion bolt having one end protruding outside the pack cover and the other end passing through the pack cover and coupling to at least one of the horizontal partition wall and the vertical partition wall, An elastic member provided between the pack cover and the one end of the expansion bolt, and elastically biasing the pack cover in one direction. The battery pack according to claim 1, characterized in that it comprises.

3. The variable coupling portion is, Further comprising a coupling housing provided on the pack cover and surrounding at least a part of the elastic member and the expansion bolt. The battery pack according to claim 2, characterized in that it comprises.

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

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

6. The battery pack according to claim 2, wherein the elastic member is 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.

7. The battery pack according to claim 2, wherein the elastic modulus of the elastic member increases as it progresses toward the central region of the pack cover.

8. The battery pack according to claim 5, wherein a gas outlet through which vent gas is discharged is provided in one wall of the pack tray.

9. A rupture film is provided at the gas outlet, The battery pack according to claim 8, wherein the rupture film is provided with a discharge slit configured to rupture when a pressure equal to or higher than the allowable pressure is applied thereto.

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

11. The battery pack according to claim 1, wherein the pack cover includes a first pack cover adjacent to the battery module and a second pack cover disposed above the first pack cover so as to be spaced apart from the first pack cover by a predetermined interval.

12. The variable coupling part is an expansion bolt having one end coupled 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. The battery pack according to claim 11, further comprising a coupling housing provided in the second pack cover and accommodating the second elastic member and the expansion bolt therein.

13. 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. The battery pack according to claim 1, wherein the variable coupling portion is provided in a central area of the left pack cover and a central area of the right pack cover.

14. An automobile, comprising the battery pack according to any one of claims 1 to 13.

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