Explosion-proof valve and battery pack

Abstract

The utility model relates to the technical field of battery production, in particular to an anti-explosion valve and a battery pack, the anti-explosion valve comprises a valve body, an end cover and a piston rod, the end cover is in sealing fit with the valve body, and the valve body is provided with a pressure relief cavity with one open end in the axial direction and a containing cavity with two open ends in the axial direction; the end cover blocks the open end of the pressure relief cavity and the first open end of the containing cavity. The piston rod is slidably arranged in the containing cavity through the second open end of the containing cavity and can slide towards the end cover when impacted by airflow. According to the anti-explosion valve, air pressure in the battery pack shell can drive the piston rod to slide towards the end cover, so that air in the containing cavity is compressed, the pressure intensity is increased, then the air pressure change in the battery pack shell is accurately reflected, when the pressure reaches the opening degree, the end cover is separated from the valve body, and air in the battery pack shell is exhausted to the outside through the pressure relief cavity; the explosion-proof response speed is high, and the safety of the battery pack is high.

Description

Technical Field

[0001] The present application relates to the field of battery production technology, and in particular to an explosion-proof valve and a battery pack. Background Art

[0002] As the core of new energy electric vehicles, the safety and working reliability of the battery pack directly affect the safety of new energy electric vehicles. If the battery pack is in a thermal runaway state, high-temperature and high-pressure gas will be generated in its shell, which may induce violent fire and explosion, and even cause casualties and property losses. In order to ensure the safety of the battery pack, one or more explosion-proof valves are usually installed on its shell to discharge the high-temperature and high-pressure gas in its shell in time.

[0003] Most of the existing explosion-proof valves are ejector-type explosion-proof valves or spring-type explosion-proof valves. Among them, the ejector-type explosion-proof valve needs to pierce the explosion-proof sheet by the ejector to achieve pressure relief. The required opening pressure is relatively large, resulting in a long response time of the explosion-proof valve and the inability to achieve instant opening. The spring-type explosion-proof valve pushes the valve body through the spring to achieve pressure relief. However, as the pressure in the battery pack shell gradually decreases, the spring drives the valve body to close automatically, affecting the pressure relief rate of the explosion-proof valve, thereby affecting the pressure relief effect of the explosion-proof valve, and the safety of the battery pack cannot be guaranteed.

[0004] In view of this, this application is specially filed. Utility Model Content

[0005] The present application provides an explosion-proof valve and a battery pack to solve the problem of how to improve the explosion-proof response speed of the explosion-proof valve.

[0006] In one aspect, the present application provides an explosion-proof valve, comprising:

[0007] A valve body, the valve body having a pressure relief cavity with one end open along its axial direction and a receiving cavity with two ends open along its axial direction;

[0008] An end cover, the end cover is sealingly fitted with the valve body and is used to block the open end of the pressure relief chamber and the first open end of the accommodating chamber;

[0009] A piston rod is slidably disposed in the accommodating cavity through the second open end of the accommodating cavity. When the piston rod is impacted by airflow, it can slide toward the end cover so that the end cover is separated from the valve body and the open end of the pressure relief cavity is opened.

[0010] In some embodiments, the valve body comprises:

[0011] A first cylinder, wherein a first end of the first cylinder along the axial direction is an open end, a second end of the first cylinder along the axial direction is a closed end, and a through hole is provided at the closed end;

[0012] The second cylinder is a hollow structure that penetrates through both ends of the second cylinder along its axial direction and is sleeved in the first cylinder through the through hole, and the second cylinder defines the accommodating cavity.

[0013] The pressure relief chamber is defined between the inner side of the first cylinder and the outer side of the second cylinder, the end covers are respectively sealed with the first end of the first cylinder and the first open end of the second cylinder, and the piston rod is slidably disposed in the accommodating chamber through the second open end of the second cylinder.

[0014] In some embodiments, the end cap comprises:

[0015] A cover body, the cover body is sealingly fitted with the first end of the first cylinder body, and is used to block the open end of the pressure relief chamber;

[0016] An extension tube is connected to the cover body, extends toward the second tube body, and is inserted into the accommodating cavity through the first open end of the second tube body.

[0017] In some embodiments, the extension tube is a hollow structure penetrating along both ends of its axial direction, and the cover body has an air chamber cavity connected to the interior of the extension tube, and the air chamber cavity is connected to the accommodating cavity through the extension tube.

[0018] In some embodiments, the outer side of the extension tube has a step portion protruding outward in its radial direction, the extension tube is inserted into the accommodating cavity, and the step portion abuts against the first open end of the second cylinder.

[0019] In some embodiments, a groove is provided at the first end of the first cylinder, and a sealing member is provided between the end cover and the groove so that the end cover is sealed and fitted with the first end of the first cylinder.

[0020] In some embodiments, the second cylinder is sleeved in the first cylinder through the through hole, and the second open end of the second cylinder is located outside the first cylinder and close to the closed end of the first cylinder.

[0021] In some embodiments, the closed end of the first cylinder is provided with air holes, and a plurality of the air holes are arranged in sequence and at intervals along the circumferential direction and / or radial direction of the first cylinder.

[0022] In some embodiments, the piston rod comprises:

[0023] A piston rod body, the piston rod body having a first end and a second end oppositely disposed along its axial direction, the first end facing the end cover;

[0024] A covering member is covered on the first end portion, and the covering member can be sealed and fitted with the inner wall of the second tube.

[0025] On the other hand, the present application also provides a battery pack, comprising any of the explosion-proof valves described above.

[0026] After adopting the above technical solution, the present application has the following beneficial effects compared with the prior art.

[0027] 1. The explosion-proof valve in the present application, the air pressure in the battery pack shell can drive the piston rod to slide toward the end cover, so that the air in the accommodating chamber is compressed and the pressure increases, thereby accurately reflecting the air pressure changes in the battery pack shell. When the pressure reaches the opening level, the end cover separates from the valve body, and the gas in the battery pack shell is discharged to the outside through the pressure relief chamber. The explosion-proof response speed is fast and the battery pack is highly safe.

[0028] 2. The explosion-proof valve in the present application sets up independent pressure relief chambers and containing chambers, so that the air pressure in the containing chamber is directly related to the air pressure changes in the battery pack shell, thereby preventing the air pressure changes in the pressure relief chamber from interfering with the accuracy of the explosion-proof response. It has a simple structure, low cost, and high reliability.

[0029] 3. The battery pack in the present application includes the explosion-proof valve in the present application, and therefore also includes all the above-mentioned advantages of the explosion-proof valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the installation of the explosion-proof valve and the battery pack housing in the embodiment of the present application;

[0031] Figure 2 yes Figure 1 A partial enlarged view of the middle A;

[0032] Figure 3 Schematic diagram of the installation of the explosion-proof valve and the battery pack housing in the embodiment of the present application;

[0033] Figure 4 yes Figure 3 A partial enlarged view of point B in the middle;

[0034] Figure 5 is an exploded view of the explosion-proof valve in the embodiment of the present application;

[0035] Figure 6 It is a front view of the explosion-proof valve in the embodiment of the present application;

[0036] Figure 7 yes Figure 6 Sectional view along CC direction;

[0037] Figure 8 It is a schematic diagram of the structure of the valve body in the embodiment of the present application.

[0038] In the figure: 100, explosion-proof valve; 110, valve body; 111, pressure relief chamber; 112, accommodating chamber; 113, first cylinder; 1131, first end; 1132, closed end; 1133, groove; 1134, air vent; 114, second cylinder; 1141, first open end; 1142, second open end; 120, end cover; 121, cover body; 122, extension cylinder; 1221, step portion; 123, air chamber cavity; 130, piston rod; 131, piston rod body; 1311, first end; 1312, second end; 132, covering member; 140, sealing member; 200, battery pack shell; 210, lower shell; 220, explosion-proof port. DETAILED DESCRIPTION

[0039] The technical solution of the present application will be described clearly and completely in conjunction with the embodiments below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0040] In the embodiment of the present application, an explosion-proof valve 100 is provided, which is installed on the battery pack housing 200. For the specific structure of the explosion-proof valve 100, please refer to Figures 1 to 8 , which includes a valve body 110, an end cover 120 and a piston rod 130, wherein the end cover 120 is sealed and fitted with the valve body 110, wherein the valve body 110 has a pressure relief chamber 111 with one end open along its axial direction and a receiving chamber 112 with two ends open along its axial direction; the end cover 120 is used to block the open end of the pressure relief chamber 111 and the first open end 1141 of the receiving chamber 112; the piston rod 130 is slidably disposed in the receiving chamber 112 through the second open end 1142 of the receiving chamber 112, and the piston rod 130 can slide toward the end cover 120 when impacted by airflow, so that the end cover 120 is separated from the valve body 110 and the open end of the pressure relief chamber 111 is opened.

[0041] According to the explosion-proof valve 100 applied for, the air pressure in the battery pack shell 200 can drive the piston rod 130 to slide toward the end cover 120, so that the air in the accommodating chamber 112 is compressed and the pressure increases, thereby accurately reflecting the changes in the air pressure in the battery pack shell 200. When the pressure reaches the opening level, the end cover 120 separates from the valve body 110, and the gas in the battery pack shell 200 is discharged to the outside through the pressure relief chamber 111. The explosion-proof response speed is fast and the battery pack safety is high.

[0042] like Figure 7 and Figure 8As shown, the pressure relief chamber 111 and the accommodating chamber 112 are independently arranged, so that the air pressure in the accommodating chamber 112 is directly related to the air pressure change in the battery pack shell 200, preventing the air pressure change in the pressure relief chamber 111 from interfering with the accuracy of the explosion-proof response. The structure is simple, the cost is low, and the reliability is high.

[0043] like Figure 7 and Figure 8 As shown, the volume of the pressure relief chamber 111 is greater than the volume of the accommodating chamber 112, which is beneficial for the gas in the battery pack shell 200 to flow quickly to the pressure relief chamber 111, avoiding the risk of explosion due to the gas pressure in the battery pack shell 200, and is also beneficial for the gas in the battery pack shell 200 to push the piston rod 130 to slide quickly toward the end cover 120, thereby improving the explosion-proof response speed of the explosion-proof valve 100.

[0044] For the specific structure of the valve body 110, please refer to Figure 4 , Figure 5 , Figure 7 and Figure 8 , which includes a first barrel 113 and a second barrel 114, wherein the first barrel 113 has an open end at its first end 1131 along its axial direction, and a closed end 1132 at its second end along its axial direction, and the closed end 1132 is provided with a through hole; the second barrel 114 is a hollow structure passing through both ends along its axial direction and is sleeved in the first barrel 113 through the through hole, and a accommodating chamber 112 is defined in the second barrel 114, and a pressure relief chamber 111 is defined between the inner side of the first barrel 113 and the outer side of the second barrel 114, thereby forming a pressure relief chamber 111 and an accommodating chamber 112 that are independently arranged from each other, and the air pressure change in the accommodating chamber 112 can accurately reflect the air pressure change in the battery pack shell 200, and the volume of the pressure relief chamber 111 is greater than the volume of the accommodating chamber 112, and the explosion-proof response time is short.

[0045] like Figure 4 and Figure 7 As shown, the end cover 120 is sealed and fitted with the first end 1131 of the first cylinder 113 and the first open end 1141 of the second cylinder 114 respectively, so that the end cover 120 is detachably sealed and connected with the first cylinder 113 and the second cylinder 114 respectively, ensuring that the pressure relief chamber 111 and the accommodating chamber 112 have good air tightness.

[0046] like Figure 4 and Figure 7As shown, the piston rod 130 is slidably disposed in the accommodating chamber 112 through the second open end 1142 of the second cylinder 114. When the air pressure in the battery pack shell 200 is greater than the external atmospheric pressure, the piston rod 130 can slide toward the end cover 120 due to the impact of the airflow. If the air pressure in the battery pack shell 200 is greater than the critical air pressure, the air in the accommodating chamber 112 is compressed and the pressure increases to open the end cover 120, thereby achieving the discharge of high-temperature and high-pressure gas generated by the battery pack when thermal runaway occurs in a short time.

[0047] Preferably, the valve body 110 is an integrally formed component, that is, the first cylinder 113 and the second cylinder 114 are integrally formed, the structure is stable, not easy to deform, and the integral molding has high production efficiency, ensuring that the valve body 110 has good air tightness. Of course, the valve body 110 is an integrally formed component only as a preferred embodiment, and the first cylinder 113 and the second cylinder 114 can be fixedly connected by welding, bonding, etc.

[0048] For the specific structure of the end cap 120, please refer to Figures 5 to 7 , which includes a cover body 121 and an extension tube 122, wherein the cover body 121 is sealedly fitted with the first end 1131 of the first cylinder 113 to block the open end of the pressure relief chamber 111; the extension tube 122 is connected to the cover body 121 and extends to the second cylinder 114 and is inserted into the accommodating chamber 112 through the first open end 1141 of the second cylinder 114, and the open end of the pressure relief chamber 111 is blocked by the cover body 121, so that the end cover 120 and the first cylinder 113 are detachably sealed and connected, and the first open end 1141 of the second cylinder 114 is blocked by the extension tube 122 inserted into the accommodating chamber 112.

[0049] like Figure 5 and Figure 7 As shown, the outer side of the extension tube 122 has a step portion 1221 protruding radially outward, and the extension tube 122 is inserted into the accommodating cavity 112, and the step portion 1221 abuts against the first open end 1141 of the second cylinder 114. The abutment between the first open end 1141 of the second cylinder 114 and the step portion 1221 can limit the second cylinder 114, prevent the second cylinder 114 from shaking and causing air leakage in the accommodating cavity 112, and ensure that the second cylinder 114 and the extension tube 122 are detachably sealed and connected.

[0050] like Figure 5 and Figure 8As shown, the first end 1131 of the first cylinder 113 is provided with a groove 1133, and a seal 140 is provided between the end cover 120 and the groove 1133, so that the end cover 120 and the first end 1131 of the first cylinder 113 are sealed and fitted, thereby preventing air leakage at the connection between the end cover 120 and the first cylinder 113 and affecting the accuracy of the explosion-proof response, thereby realizing a detachable sealed connection between the end cover 120 and the first cylinder 113.

[0051] like Figure 5 and Figure 8 As shown, the groove 1133 is an annular groove extending along the circumference of the first cylinder 113, and the seal 140 is an annular sealing ring whose contour is matched with the contour of the annular groove and the end cover 120. The annular sealing ring is arranged between the end cover 120 and the first cylinder 113. The annular sealing ring has good elasticity and compressibility and is not easy to deform, so that it has good sealing performance and can effectively prevent air leakage in the pressure relief chamber 111. The annular sealing ring is sleeved on the first end 1131 of the first cylinder 113 to achieve sealing fit between the end cover 120 and the first cylinder 113, thereby further improving the air tightness of the valve body 110.

[0052] like Figure 4 , Figure 5 and Figure 7 As shown, the second cylinder 114 is sleeved in the first cylinder 113 through the through hole, and the second open end 1142 of the second cylinder 114 is located on the outside of the first cylinder 113 and close to the closed end 1132 of the first cylinder 113, which is conducive to the piston rod 130 being quickly inserted into the accommodating cavity 112 from the second open end 1142 of the second cylinder 114, so that the piston rod 130 is slidably set in the accommodating cavity 112. The assembly process is simple, the operation is labor-saving, and the assembly efficiency of the piston rod 130 can be significantly improved.

[0053] like Figure 1 and Figure 4 As shown, the end cover 120 is located outside the battery pack shell 200, at least the closed end 1132 of the first cylinder 113 is located inside the battery pack shell 200, and the pressure relief chamber 111 is used to connect the battery pack and the external environment; the second cylinder 114 is coaxially sleeved with the first cylinder 113, at least the second open end 1142 of the second cylinder 114 is located inside the battery pack shell 200, and the piston rod 130 is inserted into the accommodating chamber 112 from the second open end 1142 of the second cylinder 114, so that the air pressure in the battery pack shell 200 can drive the piston rod 130 to slide toward the end cover 120, thereby realizing an explosion-proof response, and then discharging the high-temperature and high-pressure gas in the battery pack shell 200 to the outside.

[0054] like Figure 4 , Figure 5 and Figure 8As shown, the closed end 1132 of the first cylinder 113 is provided with air holes 1134, and a plurality of air holes 1134 are arranged in sequence and at intervals along the circumference and / or radial direction of the first cylinder 113, which is safe, reliable and has high ventilation efficiency, so that the high-temperature and high-pressure gas in the battery pack shell 200 flows to the pressure relief chamber 111, thereby preventing the battery pack from catching fire or exploding.

[0055] As an embodiment not shown, the first cylinder 113 has a fire filtering structure for connecting the battery pack with the pressure relief chamber 111. When thermal runaway occurs in the battery pack, the fire filtering structure can allow the flame in the battery pack shell 200 to cool and move in the battery pack shell 200, thereby slowing down the spread of thermal runaway of the battery pack and improving the fire-blocking function and safety of the explosion-proof valve 100.

[0056] For the specific structure of the piston rod 130, please refer to Figure 4 , Figure 5 and Figure 7 , which includes a piston rod body 131 and a covering member 132, wherein the piston rod body 131 has a first end 1311 and a second end 1312 arranged opposite to each other along its axial direction, and the first end 1311 faces the end cover 120; the covering member 132 is covered on the first end 1311, and the covering member 132 can be sealed and fitted with the inner wall of the second tube. By arranging the covering member 132 at the first end 1311 of the piston rod body 131, the covering member 132 is sealed and fitted with the inner wall of the second tube, so that the accommodating chamber 112 is in a closed state, when the piston rod body 131 is impacted by the airflow and drives the covering to slide toward the end cover 120, the pressure change of the accommodating chamber 112 can truly reflect the air pressure change in the battery pack shell 200, and the reliability of the explosion-proof valve 100 is high.

[0057] Preferably, the covering member 132 is a rubber plug. The rubber plug serves as a sealing material for the second cylinder 114 . The rubber plug has good elasticity and compressibility, is not easily deformed, and can effectively prevent gas leakage in the accommodating chamber 112 .

[0058] like Figure 5 and Figure 7 As shown, the extension tube 122 is a hollow structure that passes through both ends of its axial direction, and the cover body 121 has an air chamber cavity 123 that is connected to the interior of the extension tube 122. The air chamber cavity 123 is connected to the accommodating cavity 112 through the extension tube 122. When the air pressure in the battery pack shell 200 drives the piston rod 130 to slide toward the end cover 120, the air in the accommodating cavity 112 is compressed and the pressure increases. Since the air chamber cavity 123 is connected to the accommodating cavity 112, the air in the air chamber cavity 123 is also compressed and the pressure increases, which is beneficial to the rapid separation of the end cover 120 and the valve body 110.

[0059] A battery pack is also provided in the present application. For the specific structure of the battery pack, please refer to Figures 1 to 4, which includes a battery pack housing 200 and the explosion-proof valve 100 of the above embodiment, wherein an explosion-proof opening 220 is formed on the battery pack housing 200 , and the explosion-proof valve 100 is installed at the explosion-proof opening 220 .

[0060] The battery pack according to the application includes the explosion-proof valve 100 in the present application, and thus includes all the above-mentioned advantages of the explosion-proof valve 100.

[0061] The battery pack housing 200 includes an upper housing and a lower housing 210 disposed opposite to each other. An explosion-proof opening 220 is formed on the upper housing and / or the lower housing 210. The explosion-proof valve 100 is installed at the explosion-proof opening 220. Figure 1 and Figure 2 As shown, an explosion-proof port 220 is formed on the lower shell 210, and the explosion-proof valve 100 is installed at the explosion-proof port 220, wherein the end cover 120 is located outside the lower shell 210, and at least the closed end 1132 of the first cylinder 113 is located inside the lower shell 210, and the closed end 1132 of the first cylinder 113 is provided with a plurality of air holes 1134, and the pressure relief chamber 111 is used to connect the battery pack with the external environment. When thermal runaway occurs in the battery pack, the high-temperature and high-pressure gas in the battery pack shell 200 flows to the air relief chamber through the air holes 1134.

[0062] like Figure 3 and Figure 4 As shown, the second cylinder 114 is coaxially sleeved with the first cylinder 113, and at least the second open end 1142 of the second cylinder 114 is located in the lower shell 210, and the piston rod 130 is inserted into the accommodating cavity 112 from the second open end 1142 of the second cylinder 114, so that the air pressure in the battery pack shell 200 can drive the piston rod 130 to slide toward the end cover 120. If the air pressure in the battery pack shell 200 is greater than the critical air pressure, the air in the accommodating cavity 112 is compressed and the pressure increases to open the end cover 120. Of course, the piston rod 130 can slide in the accommodating cavity 112 along the axial direction of the second cylinder 114. If the piston rod 130 is pulled into the battery pack shell 200, that is, the piston rod 130 is pulled to slide in the direction away from the end cover 120, the pressure in the air chamber cavity 123, the inside of the extension cylinder 122 and the accommodating cavity 112 becomes smaller, and the sealing pressure between the cover body 121 and the valve body 110 becomes larger, thereby realizing a detachable sealed connection between the cover body 121 and the first cylinder 113, that is, realizing a sealed fit between the end cover 120 and the valve body 110.

[0063] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0064] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0065] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0066] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0067] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. An explosion-proof valve, characterized in that: include: A valve body, the valve body having a pressure relief cavity with one end open along its axial direction and a receiving cavity with two ends open along its axial direction; An end cover, the end cover is sealingly fitted with the valve body and is used to block the open end of the pressure relief chamber and the first open end of the accommodating chamber; A piston rod is slidably disposed in the accommodating cavity through the second open end of the accommodating cavity. When the piston rod is impacted by airflow, it can slide toward the end cover so that the end cover is separated from the valve body and the open end of the pressure relief cavity is opened.

2. The explosion-proof valve according to claim 1, characterized in that: The valve body comprises: A first cylinder, wherein a first end of the first cylinder along the axial direction is an open end, a second end of the first cylinder along the axial direction is a closed end, and a through hole is provided at the closed end; The second cylinder is a hollow structure that penetrates through both ends of the second cylinder along its axial direction and is sleeved in the first cylinder through the through hole, and the second cylinder defines the accommodating cavity. The pressure relief chamber is defined between the inner side of the first cylinder and the outer side of the second cylinder, the end covers are respectively sealed with the first end of the first cylinder and the first open end of the second cylinder, and the piston rod is slidably disposed in the accommodating chamber through the second open end of the second cylinder.

3. The explosion-proof valve according to claim 2, characterized in that: The end cap comprises: A cover body, the cover body is sealingly fitted with the first end of the first cylinder body, and is used to block the open end of the pressure relief chamber; An extension tube is connected to the cover body, extends toward the second tube body, and is inserted into the accommodating cavity through the first open end of the second tube body.

4. The explosion-proof valve according to claim 3, characterized in that: The extension tube is a hollow structure penetrating along both ends of the axial direction thereof. The cover body has an air chamber cavity communicating with the interior of the extension tube, and the air chamber cavity is communicated with the accommodating cavity through the extension tube.

5. The explosion-proof valve according to claim 3, characterized in that: The outer side of the extension tube has a step portion protruding outwardly in the radial direction thereof. The extension tube is inserted into the accommodating cavity, and the step portion abuts against the first open end of the second cylinder.

6. The explosion-proof valve according to claim 2, characterized in that: A groove is provided at the first end of the first cylinder, and a sealing member is provided between the end cover and the groove so that the end cover is sealed and fitted with the first end of the first cylinder.

7. The explosion-proof valve according to claim 2, characterized in that: The second cylinder is sleeved in the first cylinder through the through hole, and the second open end of the second cylinder is located outside the first cylinder and close to the closed end of the first cylinder.

8. The explosion-proof valve according to claim 2, characterized in that: The closed end of the first cylinder is provided with air holes, and a plurality of the air holes are sequentially spaced apart along the circumferential direction and / or radial direction of the first cylinder.

9. The explosion-proof valve according to claim 2, characterized in that: The piston rod comprises: A piston rod body, the piston rod body having a first end and a second end oppositely disposed along its axial direction, the first end facing the end cover; A covering member is covered on the first end portion, and the covering member can be sealed and fitted with the inner wall of the second tube.

10. A battery pack, characterized in that: The invention comprises an explosion-proof valve as claimed in any one of claims 1 to 9.

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