Battery pack and vehicle

Abstract

The present application provides a battery pack and a vehicle. The battery pack comprises: a plurality of cells, each cell being provided with a pressure relief valve, and the area where the plurality of pressure relief valves are located being defined as a pressure relief area; and a cooling plate arranged above the cells, a cooling channel being formed in the cooling plate, wherein the cooling plate is provided with a protruding part, the protruding direction of the protruding part is away from the cells, the protruding part is aligned with the pressure relief area, the protruding part is provided with a plurality of vent holes, and the vent holes are aligned with the pressure relief valves. According to the present application, by forming the vent holes in the protruding part, the electrical distance between the plane where the vent holes is located and the pressure relief valves is increased; and by increasing the electrical distance, the probability of occurrence of insulation failures of the cooling plate at the vent holes is reduced.

Description

Battery packs and carriers

[0001] This application claims priority to Chinese patent applications filed with the China Patent Office on September 18, 2023, with application numbers 202311207833.0 and 202322541440.5. The entire contents of the above applications are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of power batteries, and specifically to a battery pack and a carrier. Background Art

[0003] Many factors affect battery safety, with thermal runaway being a fundamental cause. Therefore, to reduce temperature and burst pressure, and thus extend the battery pack's lifecycle, a heat sink is required to manage the thermal state of the battery cells.

[0004] In related cooling solutions, the cooling plate typically features an opening near the battery cell explosion-proof valve for pressure relief. This prevents the hot gases released from the battery cell from adversely affecting the cooling plate during thermal runaway. However, due to the small electrical distance between the cooling plate and the conductive connector connecting the battery cell, insulation failure is more likely to occur near the pressure relief opening than in other areas of the cooling plate. SUMMARY OF THE INVENTION

[0005] In a first aspect, an embodiment of the present application provides a battery pack, comprising:

[0006] A plurality of battery cells, each of which is provided with a pressure relief valve, and an area where the plurality of pressure relief valves are located is defined as a pressure relief area;

[0007] A cooling plate is provided above the battery cell, wherein a cooling channel is provided in the cooling plate;

[0008] The cooling plate is provided with a raised portion, the raised direction of the raised portion is away from the battery core, the raised portion is arranged in alignment with the pressure relief area, the raised portion is provided with a plurality of exhaust holes, and the exhaust holes are arranged in alignment with the pressure relief valve.

[0009] The battery pack provided in the present application increases the electrical distance between the plane where the exhaust hole is located and the pressure relief valve by arranging the exhaust hole on the raised portion, thereby reducing the probability of insulation failure of the cooling plate at the exhaust hole by increasing the electrical distance.

[0010] In a second aspect, an embodiment of the present application provides a vehicle including a battery pack, wherein the battery pack includes:

[0011] A plurality of battery cells, each of which is provided with a pressure relief valve, and an area where the plurality of pressure relief valves are located is defined as a pressure relief area;

[0012] A cooling plate is provided above the battery cell, wherein a cooling channel is provided in the cooling plate;

[0013] The cooling plate is provided with a raised portion, the raised direction of the raised portion is away from the battery core, the raised portion is arranged in alignment with the pressure relief area, the raised portion is provided with a plurality of exhaust holes, and the exhaust holes are arranged in alignment with the pressure relief valve.

[0014] The vehicle provided in this application adopts the above-mentioned battery pack, thereby increasing the electrical distance between the plane where the exhaust hole of the battery pack is located and the pressure relief valve. By increasing the electrical distance to reduce the probability of insulation failure of the cooling plate at the exhaust hole, the safety of the vehicle is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG1 is a schematic structural diagram of a battery pack provided in an embodiment of the present application;

[0016] FIG2 is a perspective exploded schematic diagram of a cooling plate provided in an embodiment of the present application;

[0017] FIG3 is a partially enlarged bottom view of a cooling plate provided in an embodiment of the present application. Modes for Carrying Out the Invention

[0018] In the description of this application, unless otherwise specified or limited, the terms "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and can refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0019] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0020] In the description of this embodiment, the terms "upper," "lower," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meanings.

[0021] As shown in Figure 1, an embodiment of the present application provides a battery pack 200, including: a battery module 40 and a cooling plate 100, wherein the battery module 40 includes a plurality of battery cells, each of which is provided with a pressure relief valve 41, and the area where the plurality of pressure relief valves 41 are located is defined as a pressure relief zone 42; a cooling plate 100, which is arranged above the battery cells; wherein the cooling plate 100 is provided with a protrusion 11, the protrusion direction of the protrusion 11 is away from the battery cells, the protrusion 11 is arranged in alignment with the pressure relief zone 42, and the protrusion 11 is provided with a plurality of exhaust holes 12, and the exhaust holes 12 are arranged in alignment with the pressure relief valve 41.

[0022] In the embodiment of the present application, the exhaust hole 12 is arranged on the raised portion 11, thereby increasing the electrical distance between the plane where the exhaust hole 12 is located and the pressure relief valve 41 of the battery cell. By increasing the electrical distance, the probability of insulation failure of the cooling plate 100 at the exhaust hole 12 is reduced.

[0023] In the embodiment of the present application, the number of exhaust holes 12 is the same as the number of battery cells, and the pressure relief valves 41 of the multiple battery cells correspond to the multiple exhaust holes 12 one by one to achieve pressure relief.

[0024] Illustratively, in the embodiment of the present application, the cooling plate 100 is made of an aluminum alloy composite material, such as aluminum AL3003.

[0025] In the embodiment of the present application, the pressure relief valve 41 of the battery cell is located at the top of the battery cell. It is known that when the battery cell is depressurized, the temperature of the uncontrolled gas can reach 500-1000°C. The high-temperature gas may cause the cooling plate to melt through. At the same time, the gas released from the battery cell is blocked by the cooling plate and cannot be depressurized, resulting in an explosion. Therefore, in the embodiment of the present application, an exhaust hole 12 is provided on the cooling plate 100, which is arranged in alignment with the pressure relief valve 41 of the battery cell, to prevent the high-temperature gas from melting through the cooling plate 100 and to prevent the high-temperature gas from being discharged smoothly and causing an explosion.

[0026] In the embodiment of the present application, the exhaust hole 12 is located outside the area where the pressure relief valve 41 is located, at the edge of the projection of the plane where the pressure relief valve 41 is located. That is, by arranging the exhaust hole 12 outside the area where the pressure relief valve 41 is located, the high-temperature gas ejected from the pressure relief valve 41 is prevented from melting through the edge of the exhaust hole 12, causing the exhaust hole 12 to malfunction and thus resulting in poor discharge of the high-temperature gas. For example, the distance between the edge of the projection of the exhaust hole 12 on the plane where the pressure relief valve 41 is located and the edge of the pressure relief valve 41 is greater than or equal to 2 mm.

[0027] In an embodiment of the present application, the battery cell further includes a positive electrode column and a negative electrode column. The positive electrode column and the negative electrode column of the battery cell can be arranged on the same side of the battery cell, and the pressure relief valve 41 can be arranged on the same side as the positive electrode column or on opposite sides. The positive electrode column and the negative electrode column of the battery cell are arranged on opposite sides of the pressure relief valve 41 of the battery cell, thereby preventing ejected material from the battery cell from causing a short circuit or arcing of the electrode column, thereby effectively improving the safety of the battery pack 200.

[0028] In some embodiments, the exhaust hole 12 may be in the shape of a waist-shaped hole. In other optional embodiments, the exhaust hole 12 may also be in other shapes such as a circle or a rectangle.

[0029] As shown in Figures 1 and 2, the cooling plate 100 comprises a stacked first flat plate 21 and a second flat plate 22. The second flat plate 22 is located on the side of the first flat plate 21 away from the battery cells. The raised portion 11 (and the vent 12) are provided on the first flat plate 21. A relief cutout 24 is provided on the second flat plate 22, aligned with the raised portion 11. The raised portion 11 passes through the relief cutout 24. Optionally, the relief cutout 24 is formed by stamping.

[0030] It should be noted that if corresponding exhaust holes are provided on the second plate 22 above the first plate 21, due to process errors in the alignment of the first and second plates 21, 22, it is very easy for the exhaust holes of the first and second plates 21, 22 to be misaligned, resulting in partial blockage of the exhaust holes, thereby affecting the gas discharge effect of the cooling plate 100. The present application provides an avoidance hollow 24 on the second plate 22, which is aligned with the raised portion 11, to play a limiting role, thereby effectively avoiding the problem of partial blockage of the exhaust holes 12 caused by poor alignment of the first and second plates 21, 22.

[0031] In the embodiment of the present application, the distance between the edge of the avoidance hollow 24 and the bottom edge of the raised portion 11 is greater than or equal to 3 mm. By setting a certain distance between the edge of the avoidance hollow 24 and the bottom edge of the raised portion 11, the assembly of the first plate 21 and the second plate 22 is facilitated.

[0032] As shown in Figures 1 to 3, the raised portion 11 includes a raised sidewall 111 and a platform portion 112 connected to each other, and the exhaust hole 12 is located on the platform portion 112. The intersection of the raised sidewall 111 and the planar portion of the first flat plate 21 is a first rounded corner structure 31, and the intersection of the raised sidewall 111 and the platform portion 112 is a second rounded corner structure 32.

[0033] In the embodiment of the present application, the raised sidewall 111 forms an angle with the first flat plate 21 that is greater than 90° and less than 180°, resulting in a trapezoidal cross-sectional profile of the raised portion 11. Setting the angle between the raised sidewall 111 and the first flat plate 21 to an obtuse angle facilitates smooth separation of the raised portion 11 from the stamping film after it is formed by stamping.

[0034] The surface of the first plate 21 facing the battery core is provided with an insulating coating (not shown in the figure). Optionally, the insulating coating is formed by spraying insulating powder material, and the material of the insulating coating includes but is not limited to boron nitride.

[0035] The battery pack 200 further includes a conductive connecting sheet 43, which is located between the cooling plate and the battery cells. The battery cells are electrically connected via the conductive connecting sheet 43. The insulating coating isolates and insulates the cooling plate 100 from the conductive connecting sheet 43. Optionally, the conductive connecting sheet 43 is made of aluminum.

[0036] When the cooling plate 100 is close to the conductive connecting piece 43, insulation failure may occur due to the small electrical distance or low voltage resistance at high voltages of 400V or even 800V. In severe cases, this may lead to arcing and ignition, resulting in a fire in the entire battery pack. Therefore, the cooling plate 100 requires insulation protection. In this embodiment, an insulating powder is sprayed on the surface of the first flat plate 21 facing the battery cells to isolate the cooling plate 100 from the conductive connecting piece 43.

[0037] It should be noted that the principle of insulation spraying is mainly electrostatic adsorption. During spraying, electrostatic effect is used to adsorb fine insulating powder to the surface of the first plate 21 facing the battery cell. Therefore, optionally, the surface of the first plate 21 in the embodiment of the present application is smooth and burr-free.

[0038] It should be noted that in the related art, an opening is usually formed by punching directly in the area where the cooling plate and the battery cell pressure relief valve 41 are positioned. However, when punching and cutting the material, it is inevitable that a right-angle area will be generated, and good electrostatic adsorption cannot be performed. The right-angle area refers to the intersection of the vertical hole wall of the opening and the horizontal surface of the cooling plate. The intersection is actually a boundary line and cannot provide a good adsorption surface for the insulating powder. Since the right-angle area generated by punching and cutting the material cannot be electrostatically adsorbed well, the thickness of the layer formed by the insulating powder in this area during spraying is too low, and the pressure resistance is poor. When a large current passes through this area, it is easily broken down by the current, resulting in insulation failure.

[0039] In the embodiment of the present application, a protrusion 11 can be formed by stamping in a region of the cooling plate 100 aligned with the pressure relief region 42, and vents 12 can be stamped on the platform 112 of the protrusion 11. Providing the vents 12 in the protrusion 11 increases the electrical distance between the plane where the vents 12 are located and the conductive connecting piece 43. This increased electrical distance reduces the probability of insulation failure of the cooling plate 100 at the vent 12 without changing the pressure resistance of the region perpendicular to the vent 12.

[0040] In an embodiment of the present application, the vertical distance between the surface of the platform portion 112 facing the side of the battery cell and the conductive connecting piece 43 is greater than or equal to 4 mm (for example, 4 mm, 4.5 mm), so that there is sufficient electrical distance between the right-angle area of ​​the exhaust hole 12 and the conductive connecting piece 43 to avoid the right-angle area of ​​the exhaust hole 12 being broken down by current and causing insulation failure.

[0041] In an embodiment of the present application, the height of the raised portion 11 is at least less than 5 mm (for example, the height is 3.5 mm, 4 mm, or 4.5 mm). It should be noted that the height of the raised portion 11 refers to the vertical distance between the surface of the platform portion 112 facing the battery cell and the surface of the first flat plate 21 facing the battery cell. It should be noted that since the material of the cooling plate has a certain amount of deformation, if the height of the raised portion 11 is set too large, the thickness of the raised portion 11 may be too small or even ruptured, causing failure of the cooling plate or other safety problems. For example, the morphology of the exhaust hole 12 may be damaged, resulting in poor gas discharge and explosion when the battery cell thermal runaway occurs.

[0042] In an embodiment of the present application, the intersection of the raised side wall 111 and the flat portion of the first flat plate 21 is a first rounded structure 31, and / or the intersection of the raised side wall 111 and the platform portion 112 is a second rounded structure 32, and the first rounded structure 31 and the second rounded structure 32 are both formed by stamping and stretching. By forming the first rounded structure 31 and the second rounded structure 32, the intersection of the raised side wall 111 and the flat portion of the first flat plate 21, as well as the intersection of the raised side wall 111 and the platform portion 112, are all smooth curved surfaces. This allows for good electrostatic adsorption when spraying the insulating powder, thereby meeting the film thickness requirements of the insulating coating, improving the pressure resistance of the cooling plate 100, and thus avoiding insulation failure. In addition, since the junction between the raised side wall 111 and the flat portion of the first flat plate 21 is close to the conductive connecting piece 43 and has a small electrical distance, this position is set as the first rounded structure 31 so that the insulating powder material in this area can have a good thickness, thereby preventing large current from passing through this area and causing insulation failure due to current breakdown.

[0043] In the embodiment of the present application, the fillet radius of the first fillet structure 31 is greater than 0.5 mm, and the fillet radius of the second fillet structure 32 is greater than 0.5 mm. The fillet radius of the first fillet structure 31 and the fillet radius of the second fillet structure 32 may be the same or different. It should be understood that the larger the fillet radius, the flatter the curved surface. Therefore, by increasing the fillet radius of the first fillet structure 31 and the second fillet structure 32, their ability to absorb insulating powder can be increased, thereby increasing their withstand voltage and preventing insulation failure.

[0044] It should be noted that the present application increases the electrical distance between the cooling plate 100 and the pressure relief valve 41 of the battery cell by forming the exhaust hole 12 on the raised portion 11. Even if there is still a right-angle area produced by stamping and cutting the material at the position of the exhaust hole 12, due to the increase in the electrical distance and the fact that the entire raised portion 11 and the junction of the raised portion 11 and the planar portion of the first flat plate 21 have a thicker insulating coating film thickness and pressure resistance, the problem of insulation failure of the cooling plate 100 at the exhaust hole 12 can be effectively improved.

[0045] As shown in Figures 1 and 2, the cooling plate 100 is provided with a cooling channel 13. In some embodiments, a portion of the first plate 21 and the second plate 22 are sealed to form the cooling channel 13. Exemplarily, the sealing connection between the first plate 21 and the second plate 22 includes, but is not limited to, brazing.

[0046] It should be noted that if corresponding exhaust holes are opened on the second plate 22 on the upper side of the first plate 21, when the first plate 21 and the second plate 22 are sealed and connected, due to the process error in the alignment process of the first plate 21 and the second plate 22, it is very easy to cause the exhaust holes of the first plate 21 and the second plate 22 to be misaligned, thereby causing some exhaust holes to be blocked, thereby affecting the gas discharge effect of the cooling plate 100.

[0047] In the present application, an avoidance hollow 24 is provided on the second flat plate 22, which is aligned with the raised portion 11, so that the raised portion 11 provided with the exhaust hole 12 passes through the avoidance hollow 24, thereby playing a limiting role. In this way, while forming the cooling channel 13 through the sealed connection, the problem of blocking part of the exhaust hole 12 due to poor alignment of the first flat plate 21 and the second flat plate 22 is effectively avoided.

[0048] Exemplarily, the first flat plate 21 is provided with a flow channel convex hull 23 , the convex direction of the flow channel convex hull 23 is toward the battery cell, and the flow channel convex hull 23 is sealed with the flat surface of the second flat plate 22 to form the cooling channel 13 .

[0049] In other embodiments, the second flat plate 22 is provided with the flow channel convex 23 , the convex direction of the flow channel convex 23 is away from the battery cell, and the flow channel convex 23 is sealed with the flat surface of the first flat plate 21 to form the cooling channel 13 .

[0050] As shown in Figures 1 and 2, in the embodiment of the present application, the cooling channel 13 is distributed along the circumference of the raised portion 11. The cooling channel 13 includes a main channel 131 extending along the length of the raised portion 11, and confluence channels 132 located at both ends of the main channel in the length direction. The confluence channels 132 extend along the width of the raised portion 11 and communicate with the main channel 131. The coolant in the main channel 131 is evenly distributed and merged in the confluence channels 132, so that the coolant circulates in the cooling channel 13.

[0051] In the embodiment of the present application, the coolant may be water, which has the characteristics of large specific heat capacity and low cost. In other optional embodiments, the coolant may also be other types of liquids. The coolant may also include substances in other forms, such as gaseous or solid.

[0052] In the embodiment of the present application, a first opening 15 and a second opening 16 are provided on the second flat plate 22 . The first opening 15 and the second opening 16 are respectively located on the confluence channel 132 for connecting the cooling channel 13 and the outside of the cooling plate 100 .

[0053] Exemplarily, the first opening 15 and the second opening 16 are arranged diagonally on the cooling plate 100. Optionally, the first opening 15 is an inlet for the cooling object, and the second opening 16 is an outlet for the cooling object. Alternatively, the second opening 16 is an inlet for the cooling object, and the first opening 15 is an outlet for the cooling object.

[0054] In an embodiment of the present application, the cooling plate 100 further includes a nozzle 14 located at the first opening 15 and the second opening 16 and connected to an external coolant pipeline, thereby connecting the first opening 15 and the second opening 16 to the outside world. Optionally, the nozzle 14 is connected to the second flat plate 22 by a brazing process.

[0055] An embodiment of the present application also provides a vehicle, which includes a battery pack. The specific structure of the battery pack refers to the above embodiment. Since this vehicle adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0056] The carrier can be any vehicle that can use a battery pack, such as a vehicle, a ship, or an aircraft. For example, in the vehicle field, the carrier can be an electric vehicle, a hybrid vehicle, or any other vehicle that can use a battery pack.

[0057] The battery pack of the vehicle provided in the embodiment of the present application increases the electrical distance between the plane where the exhaust hole is located and the pressure relief valve. By increasing the electrical distance, the probability of insulation failure of the cooling plate at the exhaust hole is reduced, thereby improving the safety of the vehicle.

Claims

1. A battery pack, comprising: A plurality of battery cells, each of which is provided with a pressure relief valve, and an area where the plurality of pressure relief valves are located is defined as a pressure relief area; A cooling plate is arranged above the battery core, and a cooling channel is arranged in the cooling plate; Among them, the cooling plate is provided with a protrusion, the protrusion direction of the protrusion is away from the battery core, the protrusion is arranged in alignment with the pressure relief area, the protrusion is provided with a plurality of exhaust holes, and the exhaust holes are arranged in alignment with the pressure relief valve.

2. The battery pack according to claim 1, wherein: The cooling plate comprises a first flat plate and a second flat plate which are stacked, wherein the first flat plate is located above the battery core, and the second flat plate is located on a side of the first flat plate away from the battery core; a partial structure of the first flat plate and the second flat plate are connected by sealing to form the cooling channel; Wherein, the protrusion is arranged on the first flat plate; The second flat plate is provided with an avoidance hollow arranged in alignment with the raised portion, and the raised portion passes through the avoidance hollow.

3. The battery pack according to claim 2, wherein: The raised portion includes a raised side wall and a platform portion connected to each other, and the exhaust hole is located on the platform portion.

4. The battery pack according to claim 3, wherein: The junction between the raised side wall and the plane portion of the first flat plate is a first rounded structure.

5. The battery pack according to claim 4, wherein: The junction between the raised side wall and the platform portion is a second rounded structure.

6. The battery pack according to claim 3, wherein: The protruding side wall forms an angle with the first flat plate, and the angle is greater than 90° and less than 180°.

7. The battery pack according to claim 5, wherein: The fillet radius of the first fillet structure is greater than 0.5 mm, and / or the fillet radius of the second fillet structure is greater than 0.5 mm.

8. The battery pack according to claim 5, wherein: The fillet radius of the first fillet structure is the same as the fillet radius of the second fillet structure.

9. The battery pack according to claim 3, further comprising a conductive connecting sheet located above the battery cell, the battery cell being electrically connected via the conductive connecting sheet; in, A vertical distance between a surface of the platform portion facing the battery core and the conductive connecting sheet is greater than or equal to 4 mm.

10. The battery pack according to claim 3, wherein: A vertical distance between a surface of the platform portion facing the battery core and a surface of the first flat plate facing the battery core is less than 5 mm.

11. The battery pack according to claim 2, wherein: The distance between the edge of the avoidance hollowing and the bottom edge of the raised portion is greater than or equal to 3 mm.

12. The battery pack according to claim 1, wherein: The exhaust hole is located at the edge of the projection of the plane where the pressure relief valve is located, and is located outside the area where the pressure relief valve is located.

13. The battery pack according to claim 1, wherein: The distance between the edge of the projection of the exhaust hole on the plane where the pressure relief valve is located and the edge of the pressure relief valve is greater than or equal to 2 mm.

14. The battery pack according to claim 2, wherein: The first plate is provided with a flow channel convex hull, the convex direction of the flow channel convex hull faces the battery core, and the flow channel convex hull is sealed with the flat surface of the second plate to form the cooling channel; Alternatively, a flow channel convex hull is provided on the second flat plate, the convex hull of the flow channel is convex in a direction away from the battery core, and the flow channel convex hull is sealed with a flat surface portion of the first flat plate to form the cooling channel.

15. The battery pack according to claim 9, wherein: An insulating coating is provided on a surface of the first flat plate facing the battery core, and the cooling plate and the conductive connecting sheet are isolated and insulated by the insulating coating.

16. The battery pack according to any one of claims 1 to 15, wherein: The cooling channel is distributed along the circumference of the protrusion, and includes a main channel extending along the length direction of the protrusion, and confluence channels located at both ends of the main channel in the length direction. The confluence channels extend along the width direction of the protrusion and are connected to the main channel.

17. The battery pack according to any one of claims 1 to 15, wherein: The number of the exhaust holes is the same as the number of the battery cells; the pressure relief valves of the multiple battery cells correspond to the multiple exhaust holes one by one.

18. A vehicle, comprising a battery pack, the battery pack comprising: A plurality of battery cells, each of which is provided with a pressure relief valve, and an area where the plurality of pressure relief valves are located is defined as a pressure relief area; A cooling plate is arranged above the battery core, and a cooling channel is arranged in the cooling plate; Among them, the cooling plate is provided with a protrusion, the protrusion direction of the protrusion is away from the battery core, the protrusion is arranged in alignment with the pressure relief area, the protrusion is provided with a plurality of exhaust holes, and the exhaust holes are arranged in alignment with the pressure relief valve.

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