Explosion-proof valve, battery shell and battery pack

Abstract

The invention provides an improved explosion-proof valve, a battery shell and a battery pack aiming at the problems that an existing explosion-proof valve is easy to crack in charge-discharge circulation and cannot be normally opened under extreme conditions. Annular and directional nicks are arranged on the valve plate of the anti-explosion valve to form a weak area, and the mechanical property is optimized and the structural strength and the pressure relief sensitivity are balanced by accurately controlling the nick size (a = c = b / 2, and d: c = (0.25-0.45)). The nick layout comprises transverse nicks, longitudinal nicks and oblique nicks, a multi-dimensional stress release network can be formed through combination, the response speed is increased, and the anti-fatigue performance is improved. The battery shell comprises the anti-explosion valve and is installed on a pressure relief hole in the bottom wall of the shell, electric arc discharge is avoided, and the space utilization rate and the overall protection performance are improved. The battery pack is composed of a battery shell, a pole group and an end cover, the explosion-proof valve is installed at the bottom, high-temperature gas is prevented from impacting electronic elements, the risk of secondary damage is reduced, meanwhile, a pressure relief channel is kept unblocked through gravity, and the safety of a battery system is remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to an explosion-proof valve, a battery shell and a battery pack. BACKGROUND

[0002] With the rapid development and iteration of the automobile industry, the cost of the battery pack is particularly prominent. At the same time, during the driving process of the electric vehicle, various complex working conditions will be encountered. In order to improve the ability of the battery pack to cope with various working conditions, the structural strength of the battery pack must be improved, and the design method of the battery pack structure directly affects the overall safety performance of the battery pack.

[0003] Most of the current battery packs use aluminum profiles and explosion-proof valves on the side (arranged on the side). The explosion-proof valve on the side produces an arc phenomenon in extreme cases, which seriously affects the safety of the entire battery pack, electrical, and battery cells.

[0004] In the traditional battery pack, the heat released by the battery cells is discharged through the pressure relief valve of the entire pack, and the high-temperature hot gas is not isolated from the electricity, resulting in electrical arc phenomenon caused by high heat. At the same time, it cannot avoid the risk of cracking of the explosion-proof valve under normal charging and discharging or abnormal driving vibration working conditions, and cannot control the pressure and direction of the opening of the explosion-proof valve, which exists the safety hazard of the battery pack. SUMMARY

[0005] Therefore, it is necessary to provide an explosion-proof valve, a battery shell and a battery pack in view of the technical problem that the existing explosion-proof valve is prone to cracking risk in the battery charging and discharging cycle, and cannot be normally opened in extreme cases (such as thermal runaway), resulting in safety hazards of the battery pack, so that the battery pack has sufficient structural strength under normal working conditions, avoids accidental cracking of the explosion-proof valve, and can quickly respond and normally open in extreme cases, realizes safe pressure relief, and effectively improves the overall safety performance of the battery pack.

[0006] The first aspect of the present application provides an explosion-proof valve, comprising a valve plate provided with a notch structure and forming a weak area at the position of the notch structure, the valve plate being defined with a length direction, a width direction and a thickness direction; the notch structure comprises an annular notch and directional notches, the annular notch is arranged on the valve plate and encloses a closed area on the valve plate; the directional notches are at least one and arranged in the closed area, and the directional notches are arranged in one or all of the length direction and the width direction; wherein, along the thickness direction, the thickness of the valve plate is c, and the depth of the directional notch is d; along the length direction, the width of the bottom of the directional notch is a, the opening width of the directional notch is b, and a=c=b / 2 and d:c=(0.25-0.45) are satisfied. Through the synergistic effect of the annular notch and the directional notch, the pressure concentration is guided to the preset weak area, which not only ensures the structural strength under normal working conditions, but also ensures the rapid response under extreme conditions. Precise control of notch size (a=c=b / 2, d:c=(0.25-0.45)) optimizes the mechanical properties, balances the structural strength and pressure relief sensitivity, and avoids the structural weakness caused by too deep notches or the response lag caused by too shallow notches.

[0007] In other embodiments, the directional notch arranged along the length direction is a longitudinal notch, and the directional notch arranged along the width direction is a transverse notch. By arranging directional notches in different directions, the layout of the notches can be flexibly adjusted according to the expansion direction of the battery cell and the pressure distribution characteristics, better dispersing stress and improving the adaptability and reliability of the explosion-proof valve under different working conditions.

[0008] In other embodiments, only transverse notches are included, the number of transverse notches is at least one, and when the number of transverse notches is multiple, the multiple transverse notches are distributed in parallel and at intervals. The transverse notch is perpendicular to the expansion direction of the cell, which can effectively offset the notch fatigue caused by cyclic loading and reduce the risk of notch cracking. Multiple parallel and interval distributed transverse notches can disperse stress to multiple weak areas, improve response speed, enhance protection effect, and are suitable for scenarios where the expansion direction of the cell such as square or hard-shell battery is mainly transverse.

[0009] In other embodiments, only longitudinal notches are included, the number of longitudinal notches is at least one, and when the number of longitudinal notches is multiple, the multiple longitudinal notches are distributed in parallel and at intervals. The longitudinal notch is consistent with the long axis direction of the explosion-proof valve, which is suitable for small battery design, can realize the maximum pressure relief area in limited space, and the overall stress is relatively uniform, which can reduce the stress and cracking risk of the notch, and is particularly suitable for small electronic device batteries with limited space, such as Bluetooth earphones, smart watches, etc.

[0010] In other embodiments, the number of the transverse and longitudinal notches is at least one, and when the number of the transverse and longitudinal notches is multiple, the multiple transverse notches are parallel and spaced apart, and the multiple longitudinal notches are parallel and spaced apart. The combination of the transverse and longitudinal notches forms a grid structure, creating a multi-dimensional stress release network that can cope with complex and variable stress situations. The transverse notches mainly resist cyclic expansion stress, and the longitudinal notches provide a stable axial pressure relief path. The overall stress is evenly distributed, which can reduce the stress on the notches and the risk of cracking of the explosion-proof valve, and is suitable for application scenarios with extremely high safety requirements.

[0011] In other embodiments, when the number of the transverse and longitudinal notches is one, the transverse notch is located at the middle position of the length direction, and the longitudinal notch is arranged at the middle position of the length direction. This layout can evenly release pressure along the notch, avoid uneven pressure relief caused by single-point rupture, and better balance the structural strength and pressure relief performance, meeting the needs of some scenarios with balanced performance requirements for explosion-proof valves.

[0012] In other embodiments, the directional notch further includes an oblique notch, the number of the oblique notch is at least one, and the oblique notch extends along the length direction and the width direction. The oblique notch can adapt to the asymmetric pressure release demand through a non-orthogonal angle design, decompose linear stress into multi-directional components, further reduce local stress peak value, and improve the reliability and pressure relief efficiency of the explosion-proof valve in complex pressure environment.

[0013] In other embodiments, the shape of the oblique notch includes one or all of a straight line or a curve; the number of the oblique notch is multiple, and the multiple oblique notches are connected end to end to form a V-shaped notch, a W-shaped notch, or a snake-shaped notch. The V-shaped, W-shaped, or snake-shaped notch realizes multi-directional decomposition of the stress field, converts the traditional linear stress concentration into a surface distribution, and the circular arc notch realizes a smoother stress transition through continuous curvature change, which can further reduce the stress on the notch, prolong the service life of the explosion-proof valve, and in extreme cases, form a larger pressure relief opening area to release the internal pressure faster.

[0014] The second aspect of the present application provides a battery shell comprising the explosion-proof valve of any one of the above-mentioned embodiments, the explosion-proof valve being installed at a pressure relief hole provided on the battery shell, and the pressure relief hole being provided on the bottom wall of the battery shell. By installing the explosion-proof valve on the bottom wall of the battery shell, the side-out phenomenon of the explosion-proof valve can be avoided, and in extreme cases, the phenomenon of electrical arc can be avoided. At the same time, the space utilization rate is improved, and the wall thickness of the battery shell is increased, thereby improving the overall protection performance of the battery shell and providing more reliable safety protection for the battery.

[0015] The third aspect of the present application provides a battery pack, comprising the battery shell, further comprising: a pole group arranged in the battery shell, and an end cover connected with the battery shell for closing the pole group. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a structure diagram of the explosion-proof valve in the first embodiment of the present application.

[0017] Figure 2 It is a structure diagram of the explosion-proof valve in the second embodiment of the present application. Figure 1 It is a sectional view and a local enlarged view in the direction A.

[0018] Figure 3 It is a sectional view in the direction B. Figure 1

[0019] Figure 4 It is a structure diagram of the explosion-proof valve in the third embodiment of the present application.

[0020] Figure 5 It is a structure diagram of the explosion-proof valve in the fourth embodiment of the present application.

[0021] Figure 6 It is a structure diagram of the explosion-proof valve in the fifth embodiment of the present application.

[0022] Figure 7 It is a sectional view in the direction C. Figure 6

[0023] It is a structure diagram of the explosion-proof valve in the sixth embodiment of the present application. Figure 8

[0024] Figure 9 It is a structure diagram of the explosion-proof valve in the seventh embodiment of the present application.

[0025] Figure 10

[0026] Figure 11 It is a sectional view and a local enlarged view in the direction D. Figure 10

[0027] It is a sectional view in the direction E. Figure 12 Figure 10

[0028] It is an explosion structure diagram of the battery pack in the eighth embodiment of the present application. Figure 13 REFERENCE SIGNS:

[0029] ​​​​​

[0030] 10, explosion-proof valve; 20, battery case; 30, electrode group; 40, end cap;

[0031] 100, valve piece; 101, annular score; 102, transverse score; 103, longitudinal score; 104, V-shaped score. DETAILED DESCRIPTION

[0032] In order to make the above objectives, features and advantages of the present application more apparent, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one skilled in the art that the present application can be practiced in a variety of ways beyond the specific embodiments described herein without departing from the spirit of the present application, and that the present application is not limited to the specific embodiments disclosed below.

[0033] In the description of the present application, it should be understood that, if there are terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0034] In addition, if the terms "first", "second" appear, these terms are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, if the term "multiple" appears, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0035] In the present application, unless otherwise explicitly specified and limited, if the terms "mounting", "connecting", "connecting", "fixing" and the like appear, these terms should be interpreted broadly. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0036] In the present application, unless specifically stated and limited otherwise, if there is a description of a first feature "on" or "under" a second feature, etc., it can mean that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature "over", "above" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. The first feature "under", "below" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the first feature is lower in horizontal height than the second feature.

[0037] It should be noted that if an element is referred to as being "fixed" or "set" on another element, it can be directly on the other element or there can be an intermediate element. If an element is considered to be "connected" to another element, it can be directly connected to the other element or there can be an intermediate element. If present, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used in the present application are only for illustrative purposes and do not represent the only implementation.

[0038] The present patent is based on a new type of notch structure for high safety explosion-proof valve. Since the periphery of the explosion-proof valve is welded as a whole with the shell, and considering the opening of the explosion-proof valve, the local structure and design form of the notch are very important, which affects the normal opening of the explosion-proof valve in extreme conditions (such as thermal runaway), and the non-opening and cracking in the normal use process. If the design of this area is not reasonable during the normal charging and discharging process of the battery pack, it may cause the weak area of the explosion-proof valve to crack. To solve this problem, the notch structure of the explosion-proof valve is newly designed, further reducing the stress on the weak area of the explosion-proof valve.

[0039] The traditional single notch design is prone to accidental rupture or delayed pressure relief due to stress concentration, while the present patent, through the synergistic effect of the annular notch 101 and the directional notch, guides the pressure to the pre-set weak area, ensuring the structural strength under normal working conditions and ensuring rapid response under extreme conditions. In addition, the valve sheet 100 is made of metal sheet material (such as stainless steel or aluminum alloy), which has the characteristics of lightweight and high strength, further improving the energy density and safety redundancy of the battery pack.

[0040] The focus of this patent is to reduce the risk of cracking of the explosion-proof valve 10 during charging and discharging (such as in cyclic conditions), and to normally open in extreme cases (such as thermal runaway). Seven innovative design schemes are proposed for this purpose. The basic scheme uses a ring structure design 101, which can be combined with the following schemes as needed to further improve the function and effect of the explosion-proof valve 10. Among them, the ring notch 101 as the basic structure, through the geometric constraint of the closed area, the internal pressure is evenly distributed around the notch, avoiding local stress mutation; the directional notch (such as horizontal notch 102, vertical notch 103, diagonal notch, etc.) precisely controls the pressure relief path through the guidance of a specific direction. The combined design of the two not only optimizes the mechanical properties of the explosion-proof valve 10, but also adapts to different shapes of battery cases 20 and pressure release requirements, such as cylindrical, square or soft pack batteries.

[0041] The explosion-proof valve 10 in this patent includes a valve sheet 100 and a notch structure arranged on the valve sheet 100. The valve sheet 100 is a thin sheet, usually made of metal, but other materials can also be used. The notch structure arranged on it forms a weak area on the valve sheet 100, which will break and release heat and gas from the battery pack when subjected to a certain force.

[0042] The valve sheet 100 is in the shape of a long strip, and its specific structure includes a rectangle, an ellipse or a long circle. In this embodiment, a long circle is taken as an example. The valve sheet 100 is defined with mutually perpendicular length, width and thickness directions. The length direction is the direction of the longer side of the explosion-proof valve 10, the width direction is the direction of the narrower side of the explosion-proof valve 10, and the thickness direction is the direction corresponding to the thickness of the explosion-proof valve 10. The long circle design optimizes the pressure distribution through asymmetric opening direction (length direction is longitudinal, width direction is transverse), so that the explosion-proof valve 10 preferentially stretches along the longitudinal direction when the battery cell 20 expands, and the transverse notch 102 offsets the expansion stress through orthogonal layout to avoid premature cracking of the notch. In addition, the arc edge of the long circle structure can reduce the thermal stress concentration during welding, improving the sealing performance of the explosion-proof valve 10 and the shell 20.

[0043] The notch structure in this patent includes at least two types:

[0044] One is a ring notch 101, which forms a closed area, usually arranged near the edge of the valve sheet 100. The shape of the closed area can be the same as the contour of the valve sheet 100, or it can adopt a specific shape, such as an ellipse, a rectangle, a long circle, etc. The closed area can be regarded as a space extending in the length and width directions. The closed area in this application is slightly convex on one side, which facilitates the formation of stress concentration and improves the efficiency of explosion-proof.

[0045] The enclosed area of ​​the annular notch 101 is designed with a slight raised area (e.g., an arc-shaped or stepped protrusion) to form a local stress concentration point. When the internal pressure reaches a threshold, the raised area ruptures first, directing the pressure release toward the pressure relief holes in the housing 20, preventing disordered gas injection from damaging other components. Furthermore, the shape and size of the enclosed area can be dynamically adjusted based on the internal pressure of the battery pack. For example, a smaller enclosed area can be used in high-pressure scenarios to increase the rupture pressure threshold, while a larger enclosed area can be used in low-pressure scenarios to lower the threshold.

[0046] The other is a directional notch, which has at least one directional notch and is set in a closed area. The directional notch is set in one or all directions of the length direction and the width direction; the directional notch and the annular notch 101 may be in contact or not.

[0047] The layout strategy of the directional notches directly affects the pressure relief efficiency of the explosion-proof valve 10. When the directional notches and the annular notches 101 are in contact (as in Examples 1 to 3), the two form a continuous weak path, and the pressure is quickly released along the intersection of the notches. When the directional notches and the annular notches 101 are separated, the pressure needs to accumulate to a higher threshold before breaking through the separation area, which is suitable for scenarios with specific requirements for pressure relief delay. In addition, the number and direction combination of the directional notches (such as only horizontal 102, only vertical 103, or mixed directions) can be customized according to the expansion characteristics of different battery cells 20.

[0048] In this application, if Figures 1-10 As shown, both the directional notch and the annular notch 101 are in contact at least at two points. When in contact, the explosion-proof efficiency can be improved, and the explosion-proof valve 10 can be ruptured without excessive force.

[0049] The notched contact point design utilizes the "weak link" principle to concentrate pressure on the contact area, significantly reducing the energy required to open the valve. For example, in the early stages of thermal runaway, when pressure within the battery pack rises rapidly, the stress concentration effect at the contact point can cause the explosion-proof valve 10 to rupture within milliseconds, preventing continued pressure accumulation from causing an explosion. Furthermore, the number and location of the contact points can adjust the pressure relief speed. For example, a dual-contact point design can create two parallel pressure relief paths, further improving response efficiency.

[0050] In other embodiments, the directional notch and the annular notch 101 may also be separated. In this case, a greater force is required to open the explosion-proof valve 10 , so it needs to be arranged in combination with actual scenarios.

[0051] The interval design is suitable for scenarios with high risk of accidental opening of the explosion-proof valve 10, such as a vehicle-mounted battery system with frequent vibration. By increasing the interval of the notch, the mechanical strength of the explosion-proof valve 10 is improved, which can resist accidental breakage caused by vibration or slight collision, while still being able to open normally under extreme pressure. The optimization of the interval size needs to be combined with the calculation of the material mechanics characteristics and the pressure threshold to ensure the balance between function and safety.

[0052] It includes multiple cases, that is, the number of directional notches is one or more; only arranged in the length direction, only arranged in the width direction, and arranged in the length direction and the width direction at the same time; in addition, when the directional notches are arranged in the length direction and the width direction at the same time, it is also divided into two kinds, one is that the directional notches are multiple, part of which are arranged in the length direction and part of which are arranged in the width direction; the other is that the number of directional notches is one, which extends in the length direction and the width direction at the same time.

[0053] The combination design of multi-directional notches (such as the intersection of the transverse direction 102 and the longitudinal direction 103) disperses stress through the grid-shaped weak area, which is suitable for complex pressure distribution scenarios. For example, in a soft-pack battery, the swelling of the battery cell 20 may exhibit anisotropy, and multi-directional notches can ensure effective response regardless of the swelling direction. In addition, single-notch cross-direction extension (such as diagonal notches) decomposes linear stress into multi-directional components through the design of the inclination angle, further reducing the local stress peak.

[0054] Although there are multiple cases as described above, in the directional notch in the present application, along the thickness direction, the thickness of the valve sheet 100 is c, and the depth of the directional notch is d; along the length direction, the bottom width of the directional notch is a, the opening width of the directional notch is b, and a = c = b / 2, d:c = (0.25-0.45) are satisfied, which ensures the balance between normal working condition structural strength and timely opening in case of thermal runaway, and ensures the precision control of the notch bottom width a, the opening width b and the depth d. By setting a = c = b / 2, the notch bottom width is equal to the thickness of the valve sheet 100, so that the notch cracks uniformly under stress; the ratio design of d:c = 0.25-0.45 balances the mechanical strength and pressure relief sensitivity of the notch, avoiding the structure being too weak due to the notch being too deep or the response being delayed due to the notch being too shallow.

[0055] Specifically, in the present application, the directional notch arranged along the length direction is a longitudinal notch 103, and the directional notch arranged along the width direction is a transverse notch 102. At the same time, the directional notch in the present application also includes a diagonal notch, and the number of diagonal notches is at least one, and the diagonal notch extends along the length direction and the width direction at the same time.

[0056] The oblique notches, designed at non-orthogonal angles, can accommodate asymmetric pressure relief requirements. For example, when the gas flow direction within the battery pack is tilted, the extension of the oblique notches aligns with the airflow path, reducing gas jet resistance and improving pressure relief efficiency. Furthermore, the combination of the oblique notches with the transverse and longitudinal notches 102 and 103 creates a multi-dimensional weak network, further enhancing the reliability of the explosion-proof valve 10.

[0057] Example 1

[0058] like Figures 1-3 As shown, the explosion-proof valve 10 in this embodiment is provided with only a transverse notch 102, and a single transverse notch 102 is provided within the enclosed area. The transverse notch 102 is located in the middle of the length direction, dividing the enclosed area into two identical areas. Together with the annular notch 101, the protection of the battery is achieved. At the same time, the extension direction of the transverse notch 102 is perpendicular to the expansion direction of the battery cell. This design improves safety through the following mechanisms:

[0059] The transverse notch 102 is orthogonal to the principal stress direction, effectively offsetting notch fatigue caused by cyclic loads, improving the safety of the explosion-proof valve 10 during cycling, and reducing the risk of notch cracking;

[0060] At the same time, the ratio of the notch depth d to the thickness c of the valve plate 100 accurately controls the pressure relief threshold, thereby improving the response speed of the explosion-proof valve 10 in special environments and achieving a better protection effect.

[0061] This embodiment is suitable for square or hard-shell batteries, where the expansion direction of the battery cell 20 is primarily horizontal. The orthogonal layout of the transverse notches 102 can convert expansion stress into tensile force within the notches, preventing lateral tearing. In addition, the central location of the single transverse notch 102 allows for uniform pressure release along both ends of the notch, avoiding uneven pressure relief caused by single-point rupture. The advantages of this solution are its simple structure, low cost, and suitability for standardized battery production.

[0062] Example 2

[0063] like Figure 4 As shown, this embodiment differs from the first embodiment in that two parallel and spaced transverse notches 102 are provided, and the extension direction of the transverse notches 102 is perpendicular to the expansion direction of the battery cell. This solution enhances performance through the following improvements:

[0064] The transverse notch 102 is orthogonal to the principal stress direction, which effectively offsets the notch fatigue caused by cyclic loads, improves the safety of the explosion-proof valve 10 during cycling, and reduces the risk of notch cracking.

[0065] Pressure distribution: double notches disperse stress to three weak areas, improve response speed, improve protection effect, especially when high-temperature gas overflows from the side, if the transverse notch 102 is only arranged in the middle, the response speed will be reduced, and after pressure distribution, the response speed is better improved.

[0066] Double transverse notches 102 form a "double insurance" mechanism by parallel and interval distribution, even if one notch fails to break completely due to manufacturing defects, the other notch can still ensure the pressure relief function. In addition, the spacing design of double notches can adjust the pressure relief area, for example, smaller spacing is suitable for rapid pressure relief, and larger spacing is suitable for controllable pressure relief. This scheme is particularly suitable for high-power battery systems, which have a fast internal pressure rise rate and require multiple paths to release pressure cooperatively.

[0067] Example three

[0068] As shown in Figure 5 , different from example one and example two, this example is provided with three or more parallel transverse notches 102, which are suitable for large-capacity battery systems, and the extension direction of the transverse notch 102 is perpendicular to the expansion direction of the battery cell. This design is based on the temperature field distribution characteristics of the battery, and the multiple transverse notches 102 form a "pressure relief grid" through dense arrangement, which is suitable for super large-capacity battery systems such as energy storage power stations. The stepped breaking design of multiple notches can release pressure in stages, avoiding instantaneous high pressure impact on external equipment. For example, the first notch slightly cracks when the pressure reaches 80% of the threshold, and the subsequent notches break in turn as the pressure rises, achieving smooth release of pressure. In addition, the multi-notch design can realize graded response in different pressure intervals by adjusting the length and depth of the notch.

[0069] Example four

[0070] As shown in Figures 6-7 , only longitudinal notches 103 are provided in this example, and a single longitudinal notch 103 is arranged at the middle position in the corresponding width direction. The longitudinal notch 103 is consistent with the long axis direction of the explosion-proof valve 10, which realizes the maximum pressure relief area in a limited space; at the same time, the overall stress is more uniform, which can reduce the stress and cracking risk of the notch, and is suitable for small battery design.

[0071] The axial layout of the longitudinal notch 103 is particularly suitable for cylindrical batteries, whose battery cell 20 expands mainly in the radial direction. The longitudinal notch 103 is parallel to the expansion direction, which can effectively avoid stress concentration during the cyclic charging and discharging process. In addition, the middle position design of the single longitudinal notch 103 makes the pressure release uniformly along the whole length of the notch, forming a stable linear pressure relief channel. The advantage of this scheme is that the structure is compact, which is particularly suitable for small electronic equipment batteries with limited space, such as Bluetooth earphones, smart watches, etc. The depth and width parameters of the notch can be adjusted according to the battery capacity to ensure that reliable pressure relief function can still be realized in small size.

[0072] Example Five

[0073] As Figure 8 shown, the difference between this embodiment and Example Four is that two longitudinal scores 103 are provided in this embodiment, and the two longitudinal scores 103 are parallel and spaced apart. The two longitudinal scores 103 in this embodiment are arranged symmetrically. This design optimizes performance through the following mechanism: the double scores evenly distribute the longitudinal stress, reduce the stress on the scores, and reduce the risk of cracking of the explosion-proof valve 10.

[0074] The symmetrical design of the double longitudinal scores 103 creates a "pressure balance zone". When the internal pressure of the battery rises, both scores 103 bear the load at the same time, avoiding overloading and failure of a single score. This layout is particularly suitable for battery systems with high cycle life requirements, such as electric vehicle power batteries. In practical applications, the spacing of the two scores 103 needs to be accurately calculated, and is usually set to 1 / 3-1 / 2 of the width of the valve piece 100 to optimize stress distribution. In addition, this design also provides redundant protection, and when one score fails due to manufacturing defects, the other score can still ensure safe pressure relief.

[0075] Example Six

[0076] As Figure 9 shown, this embodiment combines the use of horizontal scores 102 and longitudinal scores 103 to form a grid-like structure, further improving the response speed of the explosion-proof valve 10.

[0077] Preferably, in this embodiment, two horizontal scores 102 and one longitudinal score 103 are used. The longitudinal score 103 is located at the middle position of the width direction of the explosion-proof valve 10, and the horizontal scores 102 are perpendicular to the expansion stress direction of the explosion-proof valve 10. This overall stress is relatively uniform, and in combination with the annular score 101, it can reduce the stress on the scores and the risk of cracking of the explosion-proof valve 10.

[0078] This hybrid score design creates a multi-dimensional stress release network that can handle complex and variable pressure situations. The horizontal scores 102 mainly resist cyclic expansion stress, and the longitudinal scores 103 provide a stable axial pressure relief path. This design shows excellent fatigue resistance, and it is particularly worth noting that the intersections of the grid structure form controllable weak points that can accurately control the initial position of the rupture and guide the orderly release of pressure. This scheme is very suitable for applications with extremely high safety requirements.

[0079] Example Seven

[0080] As Figures 10-12As shown, this embodiment employs two oblique notches, which are connected end to end to form a V-shaped notch 104 or an arc-shaped notch. Depending on the composition of the oblique notches, if the notches are straight, they form a V-shaped notch structure, while if the notches are curved, they tend to form an arc-shaped notch structure. This structure further reduces the stress on the notches of the explosion-proof valve 10 during expansion, decomposing the overall stress into multiple directions, reducing the stress on the notches and the risk of cracking the explosion-proof valve 10.

[0081] The innovative design of the V-shaped notch 104 achieves a multi-directional decomposition of the stress field, transforming traditional linear stress concentration into a planar distribution. The arc-shaped notch, through continuous curvature changes, achieves a smoother stress transition, making it particularly suitable for applications with frequent pressure fluctuations. This design can reduce the maximum stress at the notch by over 40%, significantly extending the service life of the explosion-proof valve 10. In extreme cases, the V-shaped or arc-shaped rupture pattern can create a larger pressure relief opening area, releasing internal pressure more quickly.

[0082] In other embodiments, multiple oblique notches are connected end to end to form a V-shaped notch (104), a W-shaped notch, or a serpentine notch (i.e., a structure similar to a serpentine formed by combining multiple Vs), which is designed according to the size of the explosion-proof valve 10.

[0083] Example 8

[0084] like Figure 13 As shown, this embodiment discloses a battery case 20, which includes the explosion-proof valve 10 structure of any one of Embodiments 1 to 7, wherein the explosion-proof valve 10 is installed on a pressure relief hole opened in the housing, preferably, the pressure relief hole is provided on the bottom wall of the housing. By installing the explosion-proof valve 10 on the bottom wall of the battery case 20, it is possible to avoid the explosion-proof valve 10 from protruding sideways, which may cause electrical arcing in extreme cases. At the same time, it improves space utilization and can increase the wall thickness of the battery case 20 on the side of the explosion-proof valve 10, thereby improving the overall protective performance of the battery case 20.

[0085] The installation scheme of the bottom-mounted explosion-proof valve 10 fully considers the overall safety of the battery system. First, the bottom position can prevent the released high-temperature gas from directly impacting other electronic components, reducing the risk of secondary damage. Secondly, this arrangement can use gravity to help the electrolyte and thermal runaway products stay away from the explosion-proof valve 10 and keep the pressure relief channel unobstructed. In actual design, the size of the pressure relief hole needs to be precisely matched with the rupture characteristics of the explosion-proof valve 10, usually 1.2-1.5 times the effective pressure relief area of ​​the explosion-proof valve 10. In addition, the thickened design of the bottom of the battery shell 20 (usually increasing the wall thickness by 30-50%) not only improves the mechanical strength, but also provides a better support structure for the explosion-proof valve 10 to ensure its normal operation.

[0086] Embodiment 9

[0087] The embodiment discloses a battery pack, which comprises the battery shell 20 in the embodiment eight, and further comprises the pole group 30 arranged in the battery shell 20 and the end cover 40 connected with the battery shell 20 for sealing the pole group 30.

[0088] Specifically, the explosion-proof valve 10 is installed on the pressure relief hole of the bottom wall of the battery shell 20 by laser welding, and after the pole group 30 is arranged in the battery shell 20, the end cover 40 is sealed and welded to complete the packaging, and the specific effect is described in the foregoing embodiments and will not be described here.

[0089] The technical features of the above embodiments can be combined arbitrarily, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present application.

[0090] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent application scope. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. An explosion-proof valve, characterized in that: include: A valve plate having a notch structure formed thereon and a weak area formed at the position of the notch structure, wherein the valve plate is defined in a length direction, a width direction and a thickness direction; The scoring structure includes an annular scoring and a directional scoring, wherein the annular scoring is provided on the valve plate and forms a closed area on the valve plate; There is at least one directional notch provided in the closed area, and the directional notch is provided in one or all directions of the length direction and the width direction; Wherein, along the thickness direction, the thickness of the valve plate is c, and the depth of the directional notch is d; Along the length direction, the bottom width of the directional score is a, the opening width of the directional score is b, and they satisfy a=c=b / 2, d:c=(0.25-0.45).

2. The explosion-proof valve according to claim 1, characterized in that: The directional notches arranged along the length direction are longitudinal notches, and the directional notches arranged along the width direction are transverse notches.

3. The explosion-proof valve according to claim 2, characterized in that: Only transverse notches are included, and the number of the transverse notches is at least one. When there are multiple transverse notches, the multiple transverse notches are distributed in parallel and at intervals.

4. The explosion-proof valve according to claim 2, characterized in that: Only longitudinal scores are included, the number of the longitudinal scores is at least one, and when there are multiple longitudinal scores, the multiple longitudinal scores are distributed in parallel and at intervals.

5. The explosion-proof valve according to claim 2, characterized in that: It includes transverse notches and longitudinal notches, the number of which is at least one, and when the number of both transverse notches and longitudinal notches is multiple, the multiple transverse notches are distributed in parallel and spaced apart, and the multiple longitudinal notches are distributed in parallel and spaced apart.

6. The explosion-proof valve according to claim 2, characterized in that: When the number of the transverse notch and the number of the longitudinal notch are both one, the transverse notch is located in the middle position in the length direction, and the longitudinal notch is set in the middle position in the length direction.

7. The explosion-proof valve according to any one of claims 1 or 2, characterized in that: The directional score also includes an oblique score, the number of the oblique score is at least one, and the oblique score extends in both the length direction and the width direction.

8. The explosion-proof valve according to claim 7, characterized in that: The shape of the oblique notches includes one or both of a straight line and a curved line; There are multiple oblique notches, and the multiple oblique notches are connected end to end to form a V-shaped notch, a W-shaped notch or a serpentine notch.

9. A battery case, characterized in that: It includes the explosion-proof valve according to any one of claims 1 to 8, wherein the explosion-proof valve is installed at a pressure relief hole opened on the battery shell, and the pressure relief hole is arranged on the bottom wall of the battery shell.

10. A battery pack, characterized in that: It includes the battery shell according to claim 9, and also includes: a pole group and an end cover, the pole group is arranged in the battery shell, and the end cover is connected to the battery shell to seal the pole group.

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