Pressure relief valve, top cover structure and secondary power battery

Abstract

This application discloses a pressure relief valve, a top cover structure, and a secondary power battery. The top cover of the secondary power battery has a through-hole, and a pressure relief valve is installed at the through-hole. The pressure relief valve, used in the secondary power battery, includes: an exhaust shaft with a downward-through exhaust groove at its lower end and a first through hole communicating with the exhaust groove on its side wall; a sealing ring fitted around the outside of the exhaust shaft; and a fixing plate disposed on the upper side of the exhaust shaft and configured to be fixedly connected to the top cover, with a second through hole formed on the fixing plate. This application effectively solves the problem of increased internal pressure caused by slow gas production in the secondary power battery. Simultaneously, when the secondary power battery experiences a sudden increase in gas pressure, it can also assist the explosion-proof valve in opening promptly, ensuring the safety of the secondary power battery.

Description

Technical Field

[0001] This application relates to the field of secondary power batteries, and more particularly to a pressure relief valve, a top cover structure, and a secondary power battery. Background Technology

[0002] Currently, lithium-ion and sodium-ion rechargeable batteries are gradually becoming mainstream products in the new energy industry due to their high energy density, good capacity consistency, and ability to support high-rate charging and discharging. With the increasing popularity of new energy vehicles, people are placing higher demands on fast-charging travel (i.e., high-rate fast charging of power batteries). More and more manufacturers are exploring bottom-through welding technology to address the needs of fast-charging travel, but the following common problems still exist:

[0003] 1. During the cycle of charging and discharging of a secondary power battery, the positive and negative electrode material systems will gradually generate gas, or the internal gas pressure will gradually increase under high-rate charging and discharging or high-temperature conditions, which may cause the battery to deform or pose a safety risk to the battery, ultimately affecting the battery life.

[0004] 2. If a pressure relief structure is directly introduced into the existing structure of the secondary power battery to release air and pressure, a situation may arise where air leakage prevents the internal pressure from rising, causing the explosion-proof valve to fail to open. Releasing pressure through the explosion-proof valve would also indicate a safety issue with the battery, rendering it unusable. Summary of the Invention

[0005] The purpose of this application is to provide a pressure relief valve, a top cover structure, and a secondary power battery, which can effectively solve the problem of increased internal pressure caused by slow gas production in the secondary power battery. At the same time, it can ensure that when the secondary power battery experiences a safety problem and sudden and violent gas production, the explosion-proof valve can open in time to protect the safety of the secondary power battery.

[0006] To achieve the above objectives, this application provides a pressure relief valve for a secondary power battery. The top cover of the secondary power battery has a through-hole, and the pressure relief valve is installed at the through-hole. The pressure relief valve includes:

[0007] An exhaust shaft has a downward-through exhaust groove at its lower end, and a first through hole communicating with the exhaust groove is provided on the side wall of the exhaust shaft.

[0008] A sealing ring, wherein the sealing ring is sleeved on the outside of the exhaust shaft; and

[0009] A fixing plate is disposed on the upper side of the exhaust shaft and is configured to be fixedly connected to the top cover. A second through hole is formed on the fixing plate.

[0010] When the internal air pressure of the secondary power battery is less than the first air pressure, the exhaust shaft is in the first position, and there is a gap between the fixed plate and the exhaust shaft to provide upward movement space for the exhaust shaft. The sealing ring is sealed and engaged with the exhaust shaft, and the first through hole is closed by the sealing ring.

[0011] When the internal air pressure of the secondary power battery reaches the first air pressure, the sealing ring deforms under the action of air pressure, so that an exhaust channel is formed between the sealing ring and the exhaust shaft, which connects the first through hole and the gap. The gas inside the secondary power battery flows out to the outside of the secondary power battery in sequence through the exhaust groove, the first through hole, the exhaust channel and the second through hole.

[0012] When the secondary power battery generates gas rapidly and instantaneously, the exhaust shaft is impacted by the second gas pressure inside the secondary power battery and moves upward to a second position, where the second gas pressure is greater than the first gas pressure.

[0013] When the exhaust shaft is in the first position, the upper part of the sealing ring has a first compression ratio; when the exhaust shaft is in the second position, the upper part of the sealing ring has a second compression ratio. The second compression ratio is greater than the first compression ratio to restrict the upward passage of gas from the first through hole.

[0014] Optionally, the upper part of the sealing ring protrudes inward to form a raised ring portion;

[0015] The outer wall of the exhaust shaft includes a lower outer wall, a middle outer wall, and an upper outer wall. The lower outer wall is located below the first through hole, and the middle outer wall and the upper outer wall are located above the first through hole.

[0016] The middle part of the outer wall extends outward beyond the upper part of the outer wall;

[0017] When the exhaust shaft is in the first position, the upper part of the outer wall and the convex ring contact each other, so that the upper part of the sealing ring has the first compression ratio, and the middle part of the outer wall and the sealing ring contact each other, so that the corresponding part of the sealing ring has the third compression ratio, and the third compression ratio is less than the second compression ratio.

[0018] When the exhaust shaft is in the second position, the middle part of the outer wall and the convex ring contact each other, causing the upper part of the sealing ring to have the second compression ratio.

[0019] Optionally, the third compression ratio is greater than the first compression ratio.

[0020] Optionally, the lower part of the outer wall always maintains a sealing contact with the sealing ring.

[0021] Optionally, the lower part of the outer wall contacts the sealing ring, causing the corresponding portion of the sealing ring to have a fourth compression ratio, which is greater than the first compression ratio and the third compression ratio.

[0022] Optionally, the end of the first through hole near the sealing ring is formed into a flared opening.

[0023] Optionally, the exhaust shaft includes an exhaust shaft body and an exhaust cap. The exhaust cap is fixedly installed on the exhaust shaft body or integrally formed with the exhaust shaft body. An exhaust passage is provided on the exhaust cap. When the exhaust passage is formed, the exhaust passage connects the exhaust passage and the gap.

[0024] Optionally, if the exhaust cap is fixedly installed on the top of the exhaust shaft body, one of the exhaust shaft body and the exhaust cap forms a threaded groove, and the other forms a threaded post. The threaded groove and the threaded post are adapted to be connected to fix the exhaust shaft body and the exhaust cap.

[0025] Optionally, the exhaust passage includes an annular groove formed on the lower side of the exhaust cap and a plurality of third through holes. The annular groove connects to the exhaust passage when the exhaust passage is formed, and the plurality of third through holes are distributed along the annular groove and connect the annular groove and the gap.

[0026] Optionally, a plurality of second through holes are formed on the fixing plate, and the plurality of second through holes correspond to the plurality of third through holes respectively.

[0027] Optionally, the middle part of the fixing plate is punched upward to form a boss, and a receiving space is formed on the lower side of the boss, with the top of the exhaust shaft located in the receiving space.

[0028] To achieve the above objectives, this application also provides a top cover structure for a secondary power battery. The top cover structure includes a top cover with a through mounting hole, and a pressure relief valve as described above is installed at the mounting hole.

[0029] Optionally, the bottom of the mounting hole expands outward to form a downward through mounting groove. The sealing ring includes a main body and an extension extending outward from the bottom of the main body. The main body is disposed in the mounting hole and is sealed to the inner wall of the mounting hole. The extension is installed in the mounting groove and is sealed to the upper wall of the mounting groove.

[0030] Optionally, a recessed groove is formed on the upper surface of the top cover, the mounting hole is disposed in the recessed groove, and the fixing plate is fixedly installed in the recessed groove.

[0031] To achieve the above objectives, this application also provides a secondary power battery, including the top cover structure as described above.

[0032] This application includes a pressure relief valve installed on the top cover. The pressure relief valve comprises an exhaust shaft, a sealing ring sleeved on the exhaust shaft, and a fixing plate installed on the upper end of the exhaust shaft and fixed to the top cover. The exhaust shaft has a downward-through exhaust groove and a first through hole communicating with the exhaust groove. The fixing plate has a second through hole. When the internal gas pressure of the secondary power battery is less than the first gas pressure, the sealing ring and the exhaust shaft are sealed together, forming a sealed state inside the secondary power battery, and a gap is formed between the exhaust shaft and the fixing plate that allows the exhaust shaft to move upward. When the internal gas pressure of the secondary power battery reaches the first gas pressure, the gas flowing from the exhaust groove into the first through hole impacts the sealing ring, forming an exhaust channel between the sealing ring and the exhaust shaft. The gas inside the secondary power battery is discharged to the outside of the secondary power battery through the exhaust channel and the second through hole. When the secondary power battery generates gas rapidly and instantaneously, the gas pressure impacts the exhaust groove, causing the exhaust shaft to move upward. The exhaust shaft squeezes the sealing ring, increasing the upper compression ratio of the sealing ring to block the gas from passing through, ensuring that the internal gas pressure of the secondary power battery rises rapidly, and the explosion-proof valve can open quickly. This application can effectively solve the problem of increased internal pressure caused by slow gas production in secondary power batteries. At the same time, it can also assist the explosion-proof valve to open in time when the secondary power battery produces gas rapidly and instantly, thus ensuring the safety of the secondary power battery. Attached Figure Description

[0033] Figure 1 This is a three-dimensional structural example of the top cover structure according to an embodiment of this application.

[0034] Figure 2 This is a cross-sectional structural example of the pressure relief valve in an embodiment of this application.

[0035] Figure 3 This is an example exploded view of the pressure relief valve according to an embodiment of this application.

[0036] Figure 4 This is a cross-sectional structural diagram of the exhaust shaft body according to an embodiment of this application.

[0037] Figure 5 This is a three-dimensional structural diagram of the exhaust cap according to an embodiment of this application.

[0038] Figure 6 This is a three-dimensional structural diagram of the fixing plate in an embodiment of this application.

[0039] Figure 7 This is a cross-sectional structural diagram of the sealing ring according to an embodiment of this application.

[0040] Figure 8 This is a cross-sectional structural diagram of the top cover structure according to an embodiment of this application. Detailed Implementation

[0041] To illustrate the technical content, structural features, and effects of this application in detail, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0042] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0043] Please see Figures 1 to 7 This application discloses a pressure relief valve 1 for a secondary power battery. A mounting hole 21 penetrating the top cover 2 of the secondary power battery is formed therein, and the pressure relief valve 1 is installed at the mounting hole 21.

[0044] The pressure relief valve 1 includes an exhaust shaft 11, a sealing ring 12, and a fixing plate 13. The lower end of the exhaust shaft 11 has a downwardly penetrating exhaust groove 111, and a first through hole 112 communicating with the exhaust groove 111 is formed on the side wall of the exhaust shaft 11. The sealing ring 12 is fitted onto the outside of the exhaust shaft 11. The fixing plate 13 is disposed on the upper side of the exhaust shaft 11 and is configured to be fixedly connected to the top cover 2. A second through hole 131 is formed on the fixing plate 13.

[0045] When the internal air pressure of the secondary power battery is less than the first air pressure, the exhaust shaft 11 is in the first position, and there is a gap 14 between the fixing plate 13 and the exhaust shaft 11 to provide upward movement space for the exhaust shaft 11. The sealing ring 12 is sealed and engaged with the exhaust shaft 11, and the first through hole 112 is closed by the sealing ring 12.

[0046] When the internal air pressure of the secondary power battery reaches the first air pressure, the sealing ring 12 deforms under the action of air pressure, so that the sealing ring 12 and the exhaust shaft 11 form an exhaust channel 15 that connects the first through hole 112 and the gap 14. The gas inside the secondary power battery flows out to the outside of the secondary power battery in sequence through the exhaust groove 111, the first through hole 112, the exhaust channel 15 and the second through hole 131.

[0047] When the secondary power battery generates gas rapidly and instantaneously, the exhaust shaft 11 is impacted by the second gas pressure inside the secondary power battery and moves upward to the second position. The second gas pressure is greater than the first gas pressure.

[0048] When the exhaust shaft 11 is in the first position, the upper part of the sealing ring 12 has a first compression ratio (when no deformation occurs). When the exhaust shaft 11 is in the second position, the upper part of the sealing ring 12 has a second compression ratio. The second compression ratio is greater than the first compression ratio to restrict the upward passage of gas from the first through hole 112.

[0049] It is understandable that the exhaust groove 111 extends downwards through and connects to the interior of the secondary power battery, while the second through hole 131 connects to the outside. When the internal gas pressure of the secondary power battery reaches the first gas pressure, the gas inside the secondary power battery is discharged to the second through hole 131 through the exhaust channel 15. First, it is discharged from the exhaust channel 15 to the gap 14, and then from the gap 14 to the second through hole 131.

[0050] This application has a pressure relief valve 1 installed on the top cover 2. The pressure relief valve 1 includes an exhaust shaft 11, a sealing ring 12 sleeved on the exhaust shaft 11, and a fixing plate 13 installed on the upper end of the exhaust shaft 11 and fixed on the top cover 2. The exhaust shaft 11 is provided with an exhaust groove 111 that extends downward and a first through hole 112 communicating with the exhaust groove 111. The fixing plate 13 is provided with a second through hole 131. When the internal gas pressure of the secondary power battery is less than the first gas pressure, the sealing ring 12 and the exhaust shaft 11 are sealed together, forming a sealed state inside the secondary power battery. A gap 14 is formed between the exhaust shaft 11 and the fixed plate 13, allowing the exhaust shaft 11 to move upward. When the internal gas pressure of the secondary power battery reaches the first gas pressure, the gas flowing into the first through hole 112 from the exhaust groove 111 impacts the sealing ring 12, forming an exhaust channel 15 between the sealing ring 12 and the exhaust shaft 11. The gas inside the secondary power battery is discharged to the outside of the secondary power battery through the exhaust channel 15 and the second through hole 131. When the secondary power battery generates gas rapidly and instantaneously, the second gas pressure impacts the exhaust groove 111, causing the exhaust shaft 11 to move upward. The exhaust shaft 11 compresses the sealing ring 12, increasing the upper compression ratio of the sealing ring 12 to block the gas from passing through, ensuring that the internal gas pressure of the secondary power battery rises rapidly, and the explosion-proof valve can open quickly. This application can effectively solve the problem of increased internal pressure caused by slow gas generation in the secondary power battery. At the same time, it can also assist the explosion-proof valve in opening in time when the secondary power battery generates gas rapidly and instantaneously, ensuring the safety of the secondary power battery.

[0051] Please see Figure 2 and Figure 7 In some embodiments, the upper part of the sealing ring 12 protrudes inward to form a convex ring portion 121; the outer wall 110 of the exhaust shaft 11 includes a lower outer wall portion 110a, a middle outer wall portion 110b, and an upper outer wall portion 110c, the lower outer wall portion 110a is located below the first through hole 112, and the middle outer wall portion 110b and the upper outer wall portion 110c are located above the first through hole 112;

[0052] The middle part 110b of the outer wall extends outward beyond the upper part 110c of the outer wall;

[0053] When the exhaust shaft 11 is in the first position, the upper part 110c of the outer wall contacts the convex ring 121, giving the upper part of the sealing ring 12 a first compression ratio, and the middle part 110b of the outer wall contacts the sealing ring 12, giving the corresponding part of the sealing ring 12 a third compression ratio, the third compression ratio being less than the second compression ratio.

[0054] When the exhaust shaft 11 is in the second position, the middle part 110b of the outer wall and the convex ring 121 come into contact, giving the upper part of the sealing ring 12 a second compression ratio.

[0055] Because the upper part of the sealing ring 12 protrudes inward to form a raised ring portion 121 and the middle part 110b of the outer wall of the exhaust shaft extends outward beyond the upper part 110c of the outer wall, when the exhaust shaft 11 moves upward from the first position to the second position, the middle part 110b of the outer wall moves upward to contact the raised ring portion 121. As a result, compared with the upper part 110c of the outer wall contacting the raised ring portion 121, the upper part of the sealing ring 12 is squeezed outward to a greater extent, thereby achieving a higher compression ratio than the first compression ratio and the third compression ratio, thus achieving a relatively thorough seal. When there is a sudden and violent gas generation inside the secondary power battery, it can block the gas from passing through, ensuring that the gas pressure inside the secondary power battery rises rapidly, and the explosion-proof valve can open quickly.

[0056] It is understandable that when the internal gas pressure of the secondary power battery is less than the first gas pressure, or when gas is slowly generated inside the secondary power battery, that is, when the internal gas pressure of the secondary power battery reaches the first gas pressure, the secondary power battery is in the first position. When the secondary power battery generates gas violently, the exhaust shaft 11 moves upward until it contacts the fixing plate 13, and the fixing plate 13 limits it. At this time, the exhaust shaft 11 is in the second position.

[0057] It should be noted that the lower part 110a, the middle part 110b, and the upper part 110c of the outer wall of the exhaust shaft 11 do not necessarily constitute the entirety of the outer wall 110 of the exhaust shaft 11.

[0058] Specifically, the middle part 110b of the outer wall of the exhaust shaft 11 and the upper part 110c of the outer wall of the exhaust shaft 11 are coaxial and cylindrical, and the diameter at the middle part 110b of the outer wall is larger than the diameter at the upper part 110c of the outer wall.

[0059] In some embodiments, the third compression ratio is greater than the first compression ratio to facilitate smoother gas discharge. It should be understood that the third compression ratio is not limited to being greater than the first compression ratio.

[0060] In some examples, the first compression rate is 3% to 6%, the second compression rate is greater than or equal to 15%, and the third compression rate is 4% to 8%.

[0061] Specifically, the lower part 110a of the outer wall always maintains a sealed contact with the sealing ring 12. Maintaining a sealed contact between the lower part 110a of the outer wall and the sealing ring 12 ensures that gas is discharged through the exhaust channel 15 without flowing back into the secondary power battery. Of course, the lower part 110a of the outer wall is not limited to always maintaining a sealed contact with the sealing ring 12.

[0062] Specifically, the lower part 110a of the outer wall contacts the sealing ring 12, so that the corresponding part of the sealing ring 12 has a fourth compression ratio, which is greater than the first compression ratio and the third compression ratio.

[0063] In this application example, the fourth compression ratio can be greater than or equal to 13%.

[0064] In this embodiment, the sealing ring 12 can be made of fluororubber or other materials that can deform. This application does not limit the material of the sealing ring 12.

[0065] In some embodiments, the end of the first through hole 112 near the sealing ring 12 forms a flared opening. Of course, this application does not limit the shape of the first through hole 112.

[0066] Please see Figures 3 to 5 In some embodiments, the exhaust shaft 11 includes an exhaust shaft body 11a and an exhaust cap 11b. The exhaust cap 11b is fixedly installed on the exhaust shaft body 11a. An exhaust passage 16 is provided on the exhaust cap 11b. When the exhaust passage 15 is formed, the exhaust passage 16 connects the exhaust passage 15 and the gap 14.

[0067] In some other embodiments, the exhaust shaft body 11a and the exhaust cap 11b are integrally formed. This application does not limit the structure of the exhaust shaft 11.

[0068] Specifically, the exhaust shaft body 11a is cylindrical in shape, and multiple first through holes 112 are distributed circumferentially along the exhaust shaft body 11a. Of course, the exhaust shaft body 11a can also be configured as a square column or a polygonal column, and is not limited to a cylindrical shape.

[0069] Specifically, the exhaust cap 11b is pressed onto the top of the sealing ring 12 and is sealed to the top of the sealing ring 12, which makes the structure of the pressure relief valve 1 more compact and reliable, and the gas discharged from the exhaust passage 15 can be completely discharged to the outside through the exhaust passage 16.

[0070] Specifically, if the exhaust cap 11b is fixedly installed on the top of the exhaust shaft body 11a, one of the exhaust shaft body 11a and the exhaust cap 11b forms a threaded groove 113 and the other forms a threaded post 114. The threaded groove 113 and the threaded post 114 are adapted to be connected to fix the exhaust shaft body 11a and the exhaust cap 11b.

[0071] In some other examples, the exhaust shaft body 11a and the exhaust cap 11b can also be connected by snap-fit ​​or other means. This application does not limit the installation method of the exhaust shaft body 11a and the exhaust cap 11b.

[0072] Specifically, the exhaust passage 16 includes an annular groove 161 formed on the lower side of the exhaust cap 11b and a plurality of third through holes 162. The annular groove 161 connects to the exhaust passage 15 when the exhaust passage 15 is formed, and the plurality of third through holes 162 are distributed along the annular groove 161 and connect the annular groove 161 and the gap 14.

[0073] In a specific example, the exhaust cap 11b is disc-shaped and the annular groove 161 is annular. Of course, the exhaust cap 11b is not limited to being disc-shaped, and the annular groove 161 is not limited to being annular.

[0074] An annular groove 161 is provided on the lower side of the exhaust cap 11b to connect the exhaust channel 15. Combined with the third through hole 162, when the internal pressure of the secondary power battery reaches the first pressure, the gas escaping from the exhaust channel 15 can be promptly discharged into the annular groove 161, and then discharged through the third through hole 162. Therefore, the annular groove 161 facilitates the discharge of gas from the secondary power battery, allowing the internal pressure of the secondary power battery to reach a relatively balanced state.

[0075] Specifically, a plurality of second through holes 131 are formed on the fixing plate 13, and the plurality of second through holes 131 correspond to a plurality of third through holes 162 respectively. Of course, the number and position of the second through holes 131 and the third through holes 162 do not need to correspond exactly.

[0076] Please see Figure 6 Specifically, the middle part of the fixing plate 13 is punched upward to form a boss 132, and the lower side of the boss 132 forms an accommodating space 133, with the top of the exhaust shaft 11 located in the accommodating space 133.

[0077] More specifically, multiple second through holes 131 are distributed on the boss 132.

[0078] In a specific example, the accommodating space 133 is used to accommodate the exhaust cap 11b, and a gap 14 is formed between the boss 132 and the exhaust cap 11b. The height H of the gap 14 can be selected from 0.5 to 1.5 mm. Please refer to... Figures 1 to 7 This application also discloses a top cover structure for a secondary power battery. The top cover structure includes a top cover 2, on which a through mounting hole 21 is provided. A pressure relief valve 1 as described above is installed at the mounting hole 21. An explosion-proof valve (not shown in the figure) may be installed on the top cover 2, but it is not excluded that the explosion-proof valve is not installed on the top cover 2.

[0079] Please see Figure 7 and Figure 8Specifically, the bottom of the mounting hole 21 expands outward to form a downward-through mounting groove 22. The sealing ring 12 includes a main body 12a and an extension 12b extending outward from the bottom of the main body 12a. The main body 12a is disposed in the mounting hole 21 and is sealed to the inner wall of the mounting hole 21. The extension 12b is installed in the mounting groove 22 and is sealed to the upper wall of the mounting groove 22. By forming the extension 12b at the bottom of the sealing ring 12 and forming the mounting groove 22 at the mounting hole 21 to mate with the extension 12b, it is beneficial to the stable installation of the sealing ring 12 and improve the reliability of the pressure relief valve 1.

[0080] Furthermore, the sealing ring 12 has an L-shaped cross-section in the radial direction.

[0081] Specifically, a recessed groove 23 is formed on the upper surface of the top cover 2, and the mounting hole 21 is provided in the recessed groove 23. The fixing plate 13 is fixedly installed in the recessed groove 23.

[0082] Furthermore, the side wall of the fixing plate 13 is an inclined surface that gradually slopes towards the center of the fixing plate 13 from top to bottom, and the side wall of the sinking groove 23 slopes towards the center of the mounting hole 21 from top to bottom. The side wall of the fixing plate 13 and the side wall of the sinking groove 23 are adapted to fit together and fixed.

[0083] The following describes the optional assembly process of the pressure relief valve 1 in a specific example of this application:

[0084] First, the sealing ring 12 is fitted onto the outer wall 110 of the exhaust shaft body 11a;

[0085] The sealing ring 12 and the exhaust shaft body 11a are then placed in the mounting hole 21 of the top cover 2, and the extension 12b of the sealing ring 12 is adapted to the mounting groove 22 of the top cover 2 to limit the sealing ring 12.

[0086] Next, thread the exhaust cap 11b to the exhaust shaft body 11a and fix it in place;

[0087] Finally, the fixing plate 13 is placed into the preset sinking groove 23 of the top cover 2. The side wall of the fixing plate 13 is adapted to and fits the side wall of the sinking groove 23, and is fixed by laser welding.

[0088] Please combine Figures 1 to 7 This application also discloses a secondary power battery, including the top cover structure as described above.

[0089] When the internal air pressure of the secondary power battery is low, that is, when the internal air pressure of the secondary power battery is less than the first air pressure, the sealing ring 12 seals the first through hole 112, and the top cover structure forms a sealed space that isolates the interior of the secondary power battery from the outside. External gas cannot enter the interior of the secondary power battery, and internal gas cannot be discharged from the interior of the secondary power battery.

[0090] When the internal pressure of the secondary power battery reaches a certain value, that is, when the internal pressure of the secondary power battery reaches the first pressure, the gas from the first through hole 112 impacts the sealing ring 12, and an exhaust channel 15 is formed between the sealing ring 12 and the exhaust shaft 11. The gas is discharged through the exhaust channel 15 and the second through hole 131 until the internal pressure of the secondary power battery is less than the first pressure. Then the sealing ring 12 re-seals the first through hole 112, preventing external gas from entering.

[0091] When the secondary power battery generates gas rapidly and instantaneously, the exhaust shaft 11 is impacted by the second air pressure and slides upward relative to the exhaust shaft 11. The fixing plate 13 limits the exhaust shaft 11, and the middle part 110b of the outer wall of the exhaust shaft 11 and the upper part of the sealing ring 12 make sealing contact. The upper part of the sealing ring 12 switches to a high compression ratio state. At this time, a highly sealed state is formed inside the secondary power battery, the air pressure rises rapidly, and the auxiliary explosion-proof valve opens quickly, ensuring the safety of the secondary power battery.

[0092] The above-disclosed examples are merely preferred embodiments of this application, intended to facilitate understanding and implementation by those skilled in the art. They should not be construed as limiting the scope of this application. Therefore, any equivalent variations made in accordance with the scope of this application are still within the scope of this application.

Claims

1. A pressure relief valve for a secondary power battery, wherein a mounting hole penetrating the top cover of the secondary power battery is formed therethrough, and the pressure relief valve is installed at the mounting hole, characterized in that, The pressure relief valve includes: An exhaust shaft has a downward-through exhaust groove at its lower end, and a first through hole communicating with the exhaust groove is provided on the side wall of the exhaust shaft. A sealing ring, wherein the sealing ring is sleeved on the outside of the exhaust shaft; and A fixing plate is disposed on the upper side of the exhaust shaft and is configured to be fixedly connected to the top cover. A second through hole is formed on the fixing plate. When the internal air pressure of the secondary power battery is less than the first air pressure, the exhaust shaft is in the first position, and there is a gap between the fixed plate and the exhaust shaft to provide upward movement space for the exhaust shaft. The sealing ring is sealed and engaged with the exhaust shaft, and the first through hole is closed by the sealing ring. When the internal air pressure of the secondary power battery reaches the first air pressure, the sealing ring deforms under the action of air pressure, so that an exhaust channel is formed between the sealing ring and the exhaust shaft, which connects the first through hole and the gap. The gas inside the secondary power battery flows out to the outside of the secondary power battery in sequence through the exhaust groove, the first through hole, the exhaust channel and the second through hole. When the secondary power battery generates gas rapidly and instantaneously, the exhaust shaft is impacted by the second gas pressure inside the secondary power battery and moves upward to a second position, where the second gas pressure is greater than the first gas pressure. When the exhaust shaft is in the first position, the upper part of the sealing ring has a first compression ratio; when the exhaust shaft is in the second position, the upper part of the sealing ring has a second compression ratio. The second compression ratio is greater than the first compression ratio to restrict the upward passage of gas from the first through hole.

2. The pressure relief valve as described in claim 1, characterized in that, The upper part of the sealing ring protrudes inward to form a raised ring portion; The outer wall of the exhaust shaft includes a lower outer wall, a middle outer wall, and an upper outer wall. The lower outer wall is located below the first through hole, and the middle outer wall and the upper outer wall are located above the first through hole. The middle part of the outer wall extends outward beyond the upper part of the outer wall; When the exhaust shaft is in the first position, the upper part of the outer wall and the convex ring contact each other, so that the upper part of the sealing ring has the first compression ratio, and the middle part of the outer wall and the sealing ring contact each other, so that the corresponding part of the sealing ring has the third compression ratio, and the third compression ratio is less than the second compression ratio. When the exhaust shaft is in the second position, the middle part of the outer wall and the convex ring contact each other, causing the upper part of the sealing ring to have the second compression ratio.

3. The pressure relief valve as described in claim 2, characterized in that, The third compression ratio is greater than the first compression ratio.

4. The pressure relief valve as described in claim 2, characterized in that, The lower part of the outer wall always maintains a sealed contact with the sealing ring.

5. The pressure relief valve as described in claim 2, characterized in that, The lower part of the outer wall contacts the sealing ring, causing the corresponding portion of the sealing ring to have a fourth compression ratio, which is greater than the first compression ratio and the third compression ratio.

6. The pressure relief valve as described in claim 1, characterized in that, The end of the first through hole near the sealing ring forms a flared opening.

7. The pressure relief valve as described in claim 1, characterized in that, The exhaust shaft includes an exhaust shaft body and an exhaust cap. The exhaust cap is fixedly installed on the exhaust shaft body or integrally formed with the exhaust shaft body. An exhaust passage is provided on the exhaust cap. When the exhaust passage is formed, the exhaust passage connects the exhaust passage and the gap.

8. The pressure relief valve as described in claim 7, characterized in that, If the exhaust cap is fixedly installed on the top of the exhaust shaft body, one of the exhaust shaft body and the exhaust cap forms a threaded groove, and the other forms a threaded post. The threaded groove and the threaded post are adapted to be connected to fix the exhaust shaft body and the exhaust cap.

9. The pressure relief valve as described in claim 7 or 8, characterized in that, The exhaust passage includes an annular groove formed on the lower side of the exhaust cap and a plurality of third through holes. The annular groove connects to the exhaust passage when the exhaust passage is formed, and the plurality of third through holes are distributed along the annular groove and connect the annular groove and the gap.

10. The pressure relief valve as described in claim 9, characterized in that, The fixing plate has a plurality of second through holes, and the plurality of second through holes correspond to the plurality of third through holes respectively.

11. The pressure relief valve as described in claim 9, characterized in that, The center of the fixing plate is punched upward to form a boss, and a receiving space is formed on the lower side of the boss. The top of the exhaust shaft is located in the receiving space.

12. A top cover structure for a secondary power battery, characterized in that, The top cover structure includes a top cover, which has a through mounting hole, and a pressure relief valve as described in any one of claims 1 to 11 is installed at the mounting hole.

13. The top cover structure as described in claim 12, characterized in that, The bottom of the mounting hole expands outward to form a downward through mounting groove. The sealing ring includes a main body and an extension extending outward from the bottom of the main body. The main body is disposed in the mounting hole and is sealed to the inner wall of the mounting hole. The extension is installed in the mounting groove and is sealed to the upper wall of the mounting groove.

14. The top cover structure as described in claim 12, characterized in that, A recessed groove is formed on the upper surface of the top cover, the mounting hole is provided in the recessed groove, and the fixing plate is fixedly installed in the recessed groove.

15. A secondary power battery, characterized in that, Includes the top cover structure as described in any one of claims 12 to 14.

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