Explosion-proof valve structure

Abstract

This utility model relates to an explosion-proof valve structure, belonging to the field of battery protection technology. It includes a valve body, a piston, and a guide rod. The valve body has multiple connecting pieces in its central area, with vent holes between adjacent connecting pieces and a central hole at the intersection of the connecting pieces. The piston includes a piston cap and a connecting rod. One end of the connecting rod passes through the central hole and connects to the piston cap, while the other end extends into the guide rod. A spring is provided on the connecting rod, with both ends abutting against the piston cap and the inside of the guide rod, respectively, so that the piston cap presses against the vent holes under normal conditions. The guide rod is fixedly connected to the valve body and has a limiting structure on its outer side. The wedge-shaped surface of the limiting structure forms an angle with the axis of the guide rod, which is used to mechanically lock the guide rod against the lower battery casing when the guide rod moves outward, preventing the guide rod from rebounding. When the gas pressure inside the battery pack drops to a certain level, this utility model can prevent the guide rod from rebounding, allowing the gas inside the battery pack to be completely vented, thereby ensuring the safety of the battery pack.

Description

Technical Field

[0001] This utility model belongs to the field of battery protection technology, specifically relating to an explosion-proof valve structure. Background Technology

[0002] The statements herein provide only background information related to this invention and do not necessarily constitute prior art.

[0003] With the rapid development of new energy sources, the application of power batteries is becoming more and more widespread, and the importance of studying the safety performance of battery packs is becoming increasingly prominent.

[0004] When a battery experiences thermal runaway, it generates a large amount of gas and foreign matter. If the gas cannot be discharged in time, or if the foreign matter blocks the battery pack's explosion-proof valve, the gas pressure inside the battery pack will rise rapidly, causing a fire and explosion, endangering the safety of the vehicle and its passengers.

[0005] Spring-loaded explosion-proof valves have gained widespread use due to their price advantage and reusability. However, existing explosion-proof valve structures still generally suffer from some technical problems, such as:

[0006] (1) When the battery pack experiences thermal runaway, the existing spring-loaded explosion-proof valve will open in time. However, when the pressure inside the battery pack gradually decreases below the opening pressure of the spring-loaded explosion-proof valve, the spring-loaded explosion-proof valve will rebound and re-seal with the battery pack, resulting in the remaining gas inside the pack not being completely discharged, which affects the safety of the battery pack.

[0007] (2) The existing explosion-proof valve structure only focuses on the sealing performance before pressure relief and the effectiveness during the pressure relief process, ignoring the interaction between the various components of the explosion-proof valve. As a result, although the explosion-proof valve can be opened and pressure is relieved effectively, the actual action response speed of the explosion-proof valve during the opening and closing process is unstable. Utility Model Content

[0008] The purpose of this invention is to provide an explosion-proof valve structure that can prevent the explosion-proof valve from rebounding when the gas pressure inside the battery pack drops to a certain level, allowing the gas inside the battery pack to be completely vented, thereby ensuring the safety of the battery pack.

[0009] An explosion-proof valve structure includes a valve body, a piston, and a guide rod;

[0010] The valve body has multiple connecting pieces in its central area, with vent holes between adjacent connecting pieces, and a central hole at the intersection of multiple connecting pieces.

[0011] The piston includes a piston cap and a connecting rod; one end of the connecting rod passes through the central hole and is fixedly connected to the piston cap, and the other end extends into the interior of the guide rod; and a spring is sleeved on the connecting rod, with the two ends of the spring abutting against the stepped structures inside the piston cap and the guide rod respectively, so that the piston cap is pressed and sealed to the vent hole under normal conditions.

[0012] The guide rod is a hollow cylindrical structure that is fixedly connected to the valve body. Furthermore, a wedge-shaped ring-shaped limiting structure is provided on the outside of the guide rod. The wedge-shaped surface of the limiting structure forms an angle with the axis of the guide rod, which is used to form a mechanical self-lock with the lower housing of the battery when the guide rod moves outward, preventing the guide rod from rebounding.

[0013] As a further technical solution, the valve body has multiple connecting pieces in the central area, and the valve body has a sealing groove for placing a sealing strip at the end that connects with the guide rod. The sealing groove is annular.

[0014] As a further technical solution, the sealing strip adopts a double-layer composite structure. Specifically, the inner layer of the sealing strip is fluororubber, and the outer layer is a polytetrafluoroethylene film.

[0015] As a further technical solution, the root of the connecting piece is adjacent to the sealing groove of the valve body, and the thickness of the connecting piece is greater than the thickness of the valve body.

[0016] As a further technical solution, the connecting rod is a cylindrical rod, and the length and diameter of the connecting rod are designed in proportion.

[0017] As a further technical solution, the limiting structure is wedge-shaped and made of silicone rubber.

[0018] As a further technical solution, the limiting structure is glued to the outside of the guide rod, and the limiting structure is glued to the guide rod at an angle.

[0019] As a further technical solution, the valve body has a threaded hole at the position where it connects with the connecting piece, and the explosion-proof valve structure is fixed to the lower housing of the battery by screws.

[0020] As a further technical solution, before the explosion-proof valve structure is opened, the limiting structure is located inside the lower housing.

[0021] As a further technical solution, the guide rod is fixed to the valve body by laser welding. Specifically, the guide rod is inserted into the annular boss of the valve body.

[0022] The beneficial effects of one or more of the above technical solutions:

[0023] (1) This utility model provides an explosion-proof valve, including a valve body, a piston, and a guide rod. By setting a limiting structure on the guide rod, the explosion-proof valve can open normally to release the pressure inside the battery pack when thermal runaway occurs. During the opening process of the explosion-proof valve, the limiting structure moves from inside the lower housing of the battery pack, which is used to fix the explosion-proof valve, to the outside of the lower housing along with the guide rod. When the pressure inside the battery pack is lower than the opening pressure of the spring-loaded explosion-proof valve, the limiting structure can prevent the guide rod from rebounding. Therefore, the explosion-proof valve structure of this utility model can completely vent the gas inside the battery pack, thereby ensuring the safety of the battery pack.

[0024] (2) The piston used in this utility model includes a piston cover and a connecting rod. One end of the connecting rod passes through the central hole and is fixedly connected to the piston cover, and the other end extends into the guide rod. The connecting rod is a cylindrical rod, and the length of the connecting rod is designed in proportion to its diameter, that is, the length of the connecting rod is 5-8 times the diameter. Based on this optimized length-to-diameter ratio design, the influence of inertia on the action response speed can be reduced while ensuring strength. Attached Figure Description

[0025] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute a limitation thereof.

[0026] Figure 1 This is a schematic diagram of the overall structure of the explosion-proof valve in an embodiment of this utility model.

[0027] Figure 2 This is a schematic diagram of the structure in which the explosion-proof valve is fixed to the lower housing of the battery pack in an embodiment of this utility model.

[0028] Figure 3 This is a cross-sectional structural diagram of the explosion-proof valve when it is opened in an embodiment of this utility model.

[0029] In the diagram, 1 is the valve body; 2 is the piston; 21 is the piston cap; 22 is the connecting rod; 3 is the guide rod; 4 is the vent hole; 5 is the spring; 6 is the limiting structure; 7 is the connecting piece; 8 is the sealing strip; 9 is the threaded hole; and 10 is the lower housing of the battery. Detailed Implementation

[0030] The specific implementation of this embodiment will now be described with reference to the accompanying drawings.

[0031] This utility model provides an explosion-proof valve structure, including a valve body 1, a piston 2, and a guide rod 3.

[0032] The valve body 1 has a plurality of connecting pieces 7 in the central area, and vent holes 4 are provided between adjacent connecting pieces 7, and a central hole is provided at the intersection of the plurality of connecting pieces 7.

[0033] The piston 2 includes a piston cover 21 and a connecting rod 22; one end of the connecting rod 22 passes through the central hole and is fixedly connected to the piston cover 21, and the other end extends into the guide rod 3; and a spring 5 is sleeved on the connecting rod 22, the two ends of the spring 5 respectively abut against the stepped structure inside the piston cover 21 and the guide rod 3, so that the piston cover 21 presses and seals the vent hole 4 under normal conditions.

[0034] The guide rod 3 is a hollow cylindrical structure that is fixedly connected to the valve body 1. Furthermore, a wedge-shaped ring-shaped limiting structure 6 is provided on the outside of the guide rod 3. The wedge-shaped surface of the limiting structure 6 forms an angle with the axis of the guide rod 3, which is used to form a mechanical self-lock with the lower housing of the battery when the guide rod moves outward, preventing the guide rod 3 from rebounding.

[0035] Based on the above structural design, when the gas pressure inside the battery pack drops to a certain level, this invention can prevent the explosion-proof valve from rebounding, allowing the gas inside the battery pack to be completely vented, thereby ensuring the safety of the battery pack. To facilitate understanding of the technical solution of this invention, the specific implementation methods of the technical solution of this invention will be further explained and described below.

[0036] Reference Figure 1 The guide rod 3 is a hollow cylindrical structure. Specifically, the guide rod 3 is fixed to the valve body 1 by laser welding, and the guide rod 3 is inserted into the annular boss of the valve body 1. Thus, the hollow cylindrical cavity of the guide rod 3 is connected to the vent hole 4 of the valve body 1, forming a gas release channel to ensure that the gas in the battery pack is discharged through the interior of the guide rod 3. The annular boss (not shown in the figure) is an annular protrusion extending outward from the end of the valve body 1. The tight fit between the annular boss and the guide rod 3 can help to press the sealing strip 8 tightly, further blocking the gas leakage path.

[0037] Reference Figure 3 The valve body 1 has multiple connecting pieces 7 in the central area, with vent holes 4 between adjacent connecting pieces 7, and a central hole at the intersection of multiple connecting pieces 7.

[0038] Specifically, multiple connecting pieces 7 are made of stainless steel and are radially distributed with the center of the valve body 1 as the origin. The edges of the connecting pieces 7 are rounded to avoid stress concentration and reduce turbulent resistance when airflow passes through the vent holes 4. Furthermore, approximately fan-shaped vent holes 4 are formed between adjacent connecting pieces 7; through the vent holes 4, the gas generated inside the battery pack can be discharged, reducing the gas pressure inside the battery pack. That is, when the explosion-proof valve is closed, the piston 2 is pressed against the vent holes 4, and there is no gas exchange between the gas inside the battery pack and the outside; when the explosion-proof valve is open, the piston 2 opens upwards and leaks through the vent holes 4, at which time the high-pressure gas inside the battery pack flows with the outside gas through the vent holes, thereby reducing the gas pressure inside the battery pack. Simultaneously, a central hole (not shown in the figure) is provided at the intersection of the connecting pieces 7 to pass through the connecting rod 22 and guide its linear movement.

[0039] More specifically, the root of the connecting piece 7 is adjacent to the sealing groove (annular) of the valve body 1, and the auxiliary sealing strip 8 is pressed tightly to prevent gas from leaking from the edge of the valve body 1. At the same time, the thickness of the connecting piece 7 is greater than the thickness of the valve body body. Specifically, the thickness of the connecting piece 7 is set to 1.5 times the thickness of the valve body body 1, and a stamping integral forming process is adopted to ensure structural rigidity.

[0040] Reference Figure 1 , Figure 2 The guide rod 3 is a hollow cylindrical structure; and a limiting structure 6 is provided on the outside of the guide rod 3 to prevent the guide rod 3 from springing back. The valve body 1 has a threaded hole 9 at the position where it connects with the connecting piece 7, and the explosion-proof valve structure is fixed to the lower housing 10 of the battery by screws.

[0041] Specifically, the guide rod 3 adopts a hollow cylindrical structure. On the one hand, when the valve body 1 is fixed to the lower housing of the battery pack, a part of the guide rod can be inserted into the lower housing of the battery pack, while the other part remains outside the lower housing. On the other hand, the hollow interior of the guide rod 3 can accommodate components such as the connecting rod 22 and the spring 5. The hollow cylindrical structure design provides built-in space for the connecting rod 22 and the spring 5, integrating the piston movement assembly with the guide rod 3 into one unit, reducing external auxiliary structures, and thus minimizing the overall volume. Therefore, this invention is suitable for compact installation environments inside battery packs. At the same time, the hollow interior of the guide rod 3 can also provide a precise axial movement channel for the connecting rod 22, ensuring that the linear movement of the piston 2 is free of deviation, or controlling the deviation error within a very small range, thereby effectively avoiding sealing failure or component wear caused by misalignment.

[0042] Reference Figure 3The piston 2 includes a piston cover 21 and a connecting rod 22; one end of the connecting rod 22 passes through the central hole on the connecting piece 7 and is fixedly connected to the piston cover 21; the connecting rod 22 is located inside the guide rod 3, and a spring is sleeved on the connecting rod 22.

[0043] The connecting rod 22 is a cylindrical rod, and its length is proportional to its diameter. Specifically, the length of the connecting rod is set to 5-8 times its diameter. Based on this optimized length-to-diameter ratio design, the influence of inertia on the action response speed can be reduced while ensuring strength. This design, which balances the strength of the basic components and the action response speed of the explosion-proof valve during operation through proportional control, is unprecedented in the prior art. As a preferred embodiment, the diameter and length of the connecting rod 22 can be set to 3mm and 18mm, respectively.

[0044] The piston cover 21 is used to cover the vent hole 4 to prevent air pressure leakage inside the battery pack when the explosion-proof valve is closed, thus maintaining stable air pressure inside the battery pack. The connecting rod 22 is connected to the piston cover 21 through the central hole. Since a spring 5 is sleeved on the connecting rod 22, the two ends of the spring 5 abut against the stepped structure inside the piston cover 21 and the guide rod 3, respectively. When the pressure inside the battery pack is higher than the opening pressure of the spring explosion-proof valve, the spring explosion-proof valve opens. That is, the spring drives the connecting rod 22 to move away from the lower shell of the battery pack, and the piston cover 21 is pushed by the connecting rod 22 to move away from the lower shell of the battery pack. As a result, the piston cover 21 gradually separates from the vent hole 4, and the gas inside the battery pack can begin to exchange with the outside.

[0045] The stepped structure (not shown in the figure) is an annular protrusion inside the guide rod 3, which provides axial support to one end of the spring 5. When the piston cover 21 is pushed upward by the air pressure inside the battery pack, the spring 5 is compressed and stores elastic potential energy. When the air pressure decreases, the spring 5 receives a reaction force from the stepped structure. Therefore, the stepped structure limits the axial displacement range of the spring 5, ensuring precise and controllable opening and closing of the piston cover 21, while preventing excessive spring compression and failure. Additionally, the stepped structure provides a stable fulcrum for the spring, reducing loosening or displacement caused by long-term vibration or impact, and extending its service life. Although the spring has a rebound characteristic, the wedge-shaped limiting structure 6 on the outside of the guide rod 3 (mechanically self-locking with the lower battery housing 10) prevents the guide rod 3 from rebounding after the air pressure decreases, keeping the vent 4 open until the gas is completely vented, thus completely solving the problem of gas residue caused by the rebound of traditional spring valves.

[0046] Reference Figure 1The valve body 1 has a sealing groove for placing the sealing strip 8 at the end connected to the guide rod 3. The sealing groove is annular. Existing methods generally use ordinary rubber materials as the sealing strip. To improve the sealing performance, environmental adaptability, and synergistic effect with the overall structure of the explosion-proof valve, the sealing strip used in this invention has a double-layer composite structure. Specifically, the inner layer of the sealing strip is fluororubber, and the outer layer is covered with a polytetrafluoroethylene (PTFE) film. The inner fluororubber provides elasticity and chemical corrosion resistance, while the outer PTFE film reduces the coefficient of friction, thereby preventing the sealing strip 8 from sticking to the inner wall of the guide rod 3 during piston movement. As an optional implementation, the thickness of the PTFE film can be set between 0.1-0.3 mm, which ensures a good reduction in the coefficient of friction while keeping the overall volume of the sealing strip within a small range. Furthermore, it is combined with fluororubber, and the size of the combined sealing strip must be perfectly matched to the sealing groove.

[0047] This dual-layer composite structure utilizes functional sealing layers: the inner fluororubber layer is responsible for sealing, while the outer PTFE layer provides lubrication and protection. Their distinct functions create a synergistic effect of "sealing + friction reduction." Through thickness matching, the PTFE film thickness is controlled between 0.1 and 0.3 mm, ensuring sufficient lubrication while avoiding an excessively thick outer layer that would result in an oversized sealing strip (affecting installation space). Through adaptive design, the overall size of the sealing strip precisely matches the valve body's sealing groove, and interference fit achieves pre-compression, ensuring a tight fit between the sealing strip and the guide rod and valve body in both axial and radial directions. Therefore, this invention, through material complementarity (fluororubber's sealing properties + PTFE's lubrication) and structural optimization (thickness control + adaptive design), solves the problems of existing sealing strips, such as easy aging, high friction, and short lifespan. While improving sealing reliability, it also considers environmental adaptability and long-term maintenance costs, effectively ensuring the safety of the power battery pack, especially suitable for harsh environmental temperatures and compact internal battery pack environments.

[0048] The sealing strip 8 is fixed to the sealing groove by an interference fit. The design of the sealing strip 8 can effectively prevent the gas inside the battery from leaking into the external environment under normal operating conditions. In addition, when the internal pressure of the battery rises abnormally, the explosion-proof valve will be activated and release the internal pressure. The sealing strip 8 can ensure that the gas can be discharged in an orderly and safe manner during this process, thereby preventing the battery from exploding due to excessive internal pressure.

[0049] Reference Figure 1 , Figure 3The limiting structure 6 is glued to the outside of the guide rod 3. When the valve body 1 is fixed to the lower housing of the battery pack, a portion of the guide rod 3 can be inserted into the lower housing of the battery pack, while the other portion remains outside the lower housing. The limiting structure 6 is glued to the portion of the guide rod 3 that is inserted into the lower housing of the battery pack; that is, when the explosion-proof valve structure is not open, the limiting structure 6 is located inside the lower housing. When the air pressure inside the battery pack rises to the explosion-proof valve opening threshold, the air pressure pushes the guide rod 3 outward, and the limiting structure 6 moves with the guide rod 3 from inside the lower housing 10 to the outside. At this time, the wedge-shaped surface of the limiting structure 6 forms a mechanical latch with the lower housing 10 of the battery, generating a normal compressive force and a tangential frictional force. The normal compressive force forms a reverse support through the contact pressure between the limiting structure and the housing, offsetting the spring rebound force; the inclination angle of the wedge-shaped surface generates frictional resistance between the limiting structure and the housing, preventing the guide rod from moving in the opposite direction. This dual force effectively prevents the guide rod from rebounding after the air pressure decreases, ensuring that the vent remains open until the gas inside the battery pack is completely vented. This avoids the problem in existing technologies where spring-loaded explosion-proof valves rely on spring preload for sealing, and the spring rebounding after depressurization can cause the vent to close again, potentially leading to a secondary explosion due to residual gas.

[0050] Reference Figure 3 A wedge-shaped annular limiting structure 6 is provided on the outer side of the guide rod 3. The wedge-shaped surface of the limiting structure 6 forms an angle with the axis of the guide rod 3, which is used to mechanically lock with the lower battery housing 10 when the guide rod 3 moves outward, preventing the guide rod 3 from rebounding. Furthermore, the limiting structure 6 is made of silicone rubber; the limiting structure 6 is glued to the outer side of the guide rod 3, and the limiting structure is angled to the guide rod. Specifically, the angle formed between the limiting structure 6 and the guide rod is 65°. It should be noted that the 65° wedge angle was determined through multiple verifications. This angle ensures that the normal and tangential components of the limiting structure 6 reach the optimal ratio when the guide rod 3 moves. Specifically, at this angle, the generated normal force provides sufficient contact pressure, ensuring stable friction between the limiting structure 6 and the inner wall of the lower battery casing 10 as the guide rod 3 moves outward, preventing accidental detachment. Simultaneously, the generated tangential force allows the silicone rubber limiting structure 6 to undergo controllable deformation under high pressure, smoothly passing through the gap between the guide rod 3 and the casing 10, reducing the risk of jamming. Furthermore, when the pressure decreases and the guide rod 3 attempts to rebound, the 65° wedge angle also enables the wedge-shaped surface of the limiting structure 6 to form a "self-locking effect" with the edge of the casing, significantly increasing friction (maintaining optimal locking force compared to smaller or larger angles), effectively preventing rebound.

[0051] Specifically, when the explosion-proof valve structure is not open, the limiting structure 6 is located inside the lower housing. However, when the battery experiences thermal runaway, the gas pressure inside the battery pack rises. When the gas pressure inside the battery pack rises to a level higher than the opening pressure of the spring explosion-proof valve, the spring explosion-proof valve opens. That is, the gas pressure inside the battery pack pushes the guide rod 3 and the limiting structure forward. At the same time, since the limiting structure is made of silicone rubber, which has a certain elasticity and deformation force, the limiting structure will be pushed by the pressure from the lower housing of the battery pack through the gap between the guide rod and the lower housing of the battery pack to the outside of the lower housing. As the pressure inside the battery pack gradually decreases, when the pressure inside the battery pack is lower than the pressure of the spring explosion-proof valve, the spring explosion-proof valve will rebound. However, during the rebound process, it will be blocked by the limiting structure 6. Since the limiting structure 6 is wedge-shaped, the guide rod will not rebound back into the lower housing, allowing the remaining gas inside the battery pack to continue to escape until it is completely discharged.

[0052] Therefore, when the air pressure inside the battery pack rises to a certain level, this invention can release the pressure normally; when the air pressure inside the battery pack drops to a certain level, this invention can also prevent the guide rod from rebounding, allowing the gas inside the battery pack to be completely emptied, thereby ensuring the safety of the battery pack.

[0053] Although the specific embodiments of the present utility model have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present utility model. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solution of the present utility model are still within the scope of protection of the present utility model.

Claims

1. An explosion relief valve structure, characterized by, Includes valve body, piston, and guide rod; The valve body has multiple connecting pieces in its central area, with vent holes between adjacent connecting pieces, and a central hole at the intersection of multiple connecting pieces. The piston includes a piston cap and a connecting rod; one end of the connecting rod passes through the central hole and is fixedly connected to the piston cap, and the other end extends into the interior of the guide rod; and a spring is sleeved on the connecting rod, with the two ends of the spring abutting against the stepped structures inside the piston cap and the guide rod respectively, so that the piston cap is pressed and sealed to the vent hole under normal conditions. The guide rod is a hollow cylindrical structure that is fixedly connected to the valve body. Furthermore, a wedge-shaped ring-shaped limiting structure is provided on the outside of the guide rod. The wedge-shaped surface of the limiting structure forms an angle with the axis of the guide rod, which is used to form a mechanical self-lock with the lower housing of the battery when the guide rod moves outward, preventing the guide rod from rebounding.

2. The explosion-proof valve structure according to claim 1, wherein The valve body has multiple connecting pieces in its central area, and a sealing groove for placing a sealing strip is provided at the end of the valve body that connects with the guide rod. The sealing groove is annular.

3. The explosion-proof valve structure according to claim 2, wherein The sealing strip adopts a double-layer composite structure, with the inner layer being fluororubber and the outer layer being a polytetrafluoroethylene film.

4. The explosion-proof valve structure according to claim 1, wherein The root of the connecting piece is adjacent to the sealing groove of the valve body, and the thickness of the connecting piece is greater than the thickness of the valve body.

5. The explosion-proof valve structure according to claim 1, characterized in that, The connecting rod is a cylindrical rod, and the length and diameter of the connecting rod are designed in proportion.

6. The explosion-proof valve structure according to claim 1, characterized in that, The limiting structure is wedge-shaped and made of silicone rubber.

7. The explosion-proof valve structure according to claim 6, characterized in that, The limiting structure is glued to the outside of the guide rod, and the limiting structure is glued to the guide rod at an angle.

8. The explosion-proof valve structure according to claim 1, characterized in that, The valve body has a threaded hole at the position where it connects with the connecting piece, and the explosion-proof valve structure is fixed to the lower housing of the battery by screws.

9. The explosion-proof valve structure according to any one of claims 7-8, characterized in that, Before the explosion-proof valve structure is opened, the limiting structure is located inside the lower housing.

10. The explosion-proof valve structure according to claim 1, characterized in that, The guide rod is fixed to the valve body by laser welding, and the guide rod is inserted into the annular boss of the valve body.

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