Miniaturized anti-explosion valve

Abstract

The utility model provides a miniaturized anti-explosion valve which comprises a valve body, the valve body comprises a valve seat serving as a mounting foundation and a valve cover connected to one end of the valve seat, a pressure relief channel communicated with an inner cavity of the valve seat is formed in the valve body, and a puncturing piece is arranged on the inner surface of the valve cover; the composite explosion-proof membrane assembly is arranged in the valve seat and separates the pressure relief channel from an inner cavity of the valve seat, the composite explosion-proof membrane assembly comprises a breathable membrane providing breathability and an elastic membrane deforming after being pressed, and the breathable membrane is annularly arranged on the outer side of the elastic membrane; the distance between the puncturing piece and the elastic film ranges from 5 mm to 20 mm, the ratio of the area of the effective working area of the elastic film to the area of the effective working area of the breathable film ranges from 1 to 3, and the bursting pressure of the anti-explosion valve ranges from 3 kPa to 10 kPa. The explosion-proof valve can still have small bursting pressure even after being miniaturized.

Description

Technical Field

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

[0002] An explosion-proof valve is a safety protection device that can balance the internal and external air pressure and quickly release the pressure when the internal air pressure rises abnormally to prevent explosion caused by excessive pressure.

[0003] For example, the mandatory standard GB38031-2020 Safety Requirements for Power Batteries for Electric Vehicles focuses on strengthening the thermal safety of the battery system, and especially adds a thermal diffusion test for the battery system. It requires that after a single battery cell has thermal runaway, the entire battery system should not catch fire or explode within 5 minutes, leaving sufficient safe escape time to ensure the personal safety of drivers and passengers.

[0004] The root cause of thermal runaway of battery cells is that the exothermic side reaction inside the battery cells causes heat accumulation. The rate of heat exchange of the battery cells to the outside is lower than the rate of heat accumulation. The temperature continues to rise until it reaches the ignition point, causing combustion and explosion. In order to prevent thermal runaway accidents and avoid imbalance of pressure inside and outside the battery pack, and considering that lithium batteries will instantly produce a large amount of toxic gas when they catch fire, it is necessary to release the gas in a timely and targeted manner. As a passive safety protection measure for preventing thermal runaway in battery systems, explosion-proof valves can achieve the above requirements of maintaining pressure balance and directional gas release.

[0005] Compared with the common piston explosion-proof valve, the ejector-type explosion-proof valve is preferred due to its advantages of waterproof and dustproof in daily use, large air permeability, and good pressure relief effect after explosion. The ejector-type explosion-proof valve is waterproof and dustproof because the core component of its structural components is the waterproof and breathable membrane material, which is made of expanded polytetrafluoroethylene (e-PTFE for short). The pore size of the material is larger than the diameter of the gas molecule, so it has good air permeability, and the smaller pore size combined with its own hydrophobicity can ensure that it has dustproof and waterproof properties.

[0006] For example, in the Chinese utility model patent with authorization announcement number CN218648096U, an explosion-proof valve is disclosed, wherein the explosion-proof valve includes a valve cover and a valve body that can be engaged with each other; a waterproof and breathable membrane is arranged in the pressure relief channel of the valve body, and the waterproof and breathable membrane is a PTFE microporous membrane; a piercing piece with a sharp portion facing the waterproof and breathable membrane is arranged on the valve cover, the fixing portion of the piercing piece is arranged on the valve cover, and a notch is opened on the sharp portion of the piercing piece to form a plurality of pointed ends.

[0007] The ejector-type explosion-proof valve in the aforementioned patent can indeed play a good waterproof, breathable and explosion-proof effect, but with the improvement of the integration of equipment such as new energy vehicles, a more miniaturized requirement is put forward for the explosion-proof valve. However, for the ejector-type explosion-proof valve of the aforementioned structure, miniaturization is accompanied by a decrease in the area of ​​the PTFE microporous membrane. Under the same bursting pressure, the deformation of the PTFE microporous membrane decreases accordingly, making it difficult to contact the puncture piece and burst. Although reducing the distance between the puncture piece and the PTFE microporous membrane and increasing the porosity of the PTFE microporous membrane can reduce the bursting pressure to a certain extent, the above methods will lead to a decrease in the stability of the explosion-proof valve under vibration, and it is very easy to cause damage to the PTFE microporous membrane or even failure due to vibration. Therefore, the miniaturization of the explosion-proof valve is often accompanied by an increase in the bursting pressure. For working conditions that require high integration (miniaturization) and low bursting pressure, this problem is currently in urgent need of solution but difficult to solve.

[0008] Based on this, this application is filed. Utility Model Content

[0009] The technical problem to be solved by the utility model is to overcome the problem that the explosion-proof valve in the prior art is difficult to achieve both miniaturization and low bursting pressure, thereby providing a miniaturized explosion-proof valve.

[0010] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0011] A miniaturized explosion-proof valve comprises: a valve body, comprising a valve seat as an installation base, a valve cover joined to one end of the valve seat, a pressure relief channel connected to an inner cavity of the valve seat being provided inside the valve body, and a piercing piece being provided on the inner surface of the valve cover; a composite explosion-proof membrane assembly, which is arranged in the valve seat and isolates the pressure relief channel from the inner cavity of the valve seat, and comprises a breathable membrane providing air permeability and an elastic membrane deforming under pressure, and the breathable membrane ring is arranged on the outer side of the elastic membrane; the spacing between the piercing piece and the elastic membrane is 5 to 20 mm, the ratio of the area of ​​the effective working area of ​​the elastic membrane to the area of ​​the effective working area of ​​the breathable membrane is 1 to 3, and the explosion pressure of the explosion-proof valve is 3 to 10 kPa.

[0012] By the above technical scheme, for the aforementioned needle-puncture explosion-proof valve, miniaturization is often accompanied by an increase in burst pressure. Taking the explosion-proof valve with a designed burst pressure of 7kPa as an example, when the explosion-proof valve is miniaturized, the area of ​​the PTFE microporous membrane therein is reduced accordingly. If the PTFE microporous membrane is unchanged, then under the same burst pressure of 7kPa, the stress on the PTFE microporous membrane is unchanged (the force on the unit area of ​​the PTFE microporous membrane is unchanged), and naturally it also has the same strain (the deformation per unit area is unchanged, that is, the deformation rate of the PTFE microporous membrane is unchanged). However, the total deformation of the PTFE microporous membrane is positively correlated with the product of the deformation rate and the area. Under the premise that the deformation rate of the PTFE microporous membrane is unchanged, its total deformation amount is positively correlated with the area. Therefore, under the same burst pressure of 7kPa, with the miniaturization of the explosion-proof valve, the total deformation of the PTFE microporous membrane decreases accordingly.

[0013] Due to the working mechanism of the needle-puncture explosion-proof valve, the PTFE microporous membrane must produce a sufficient total deformation to contact the puncture piece in the explosion-proof valve and produce a pressure relief effect. The decrease in deformation caused by the miniaturization of the explosion-proof valve will inevitably lead to the inability of the PTFE microporous membrane to contact the puncture piece and destroy the pressure relief under the same bursting pressure of 7kPa. At this time, the bursting pressure of the explosion-proof valve is substantially increased, which cannot guarantee safety in working conditions with high integration and low bursting pressure requirements, and is therefore an unacceptable defect.

[0014] It is precisely for the above reasons that in order to ensure that the bursting pressure of the explosion-proof valve is not too high after miniaturization, the conventional idea is often to directly reduce the size of the explosion-proof valve proportionally, and try to put in a larger area of ​​PTFE microporous membrane in a limited space. On this basis, you can also use a PTFE microporous membrane with a slightly smaller thickness and higher porosity, or appropriately reduce the distance between the PTFE microporous membrane and the puncture piece to reduce the difficulty of bursting the explosion-proof valve after miniaturization. However, these adjustment methods can only slightly reduce the bursting pressure of the explosion-proof valve, so that the explosion-proof valve after miniaturization has an excessively high bursting pressure, and are not enough to make the explosion-proof valve have a smaller bursting pressure. In addition, for working conditions with frequent vibrations such as the battery pack of new energy vehicles, the above adjustment method will inevitably lead to a decrease in the vibration tolerance of the explosion-proof valve, thereby resulting in a decrease in the service life of the explosion-proof valve, which is also an unacceptable defect.

[0015] Different from the aforementioned adjustment, the inventors of the present application have introduced a membrane assembly with a special structure into the explosion-proof valve on the basis of miniaturization, and used it in combination with a breathable membrane with waterproof and breathable capabilities and an elastic membrane with a relatively soft texture and a large deformation under pressure, and a specific assembly method of an elastic membrane inside and a breathable membrane ring outside is adopted, which cooperates with the area ratio, the distance between the knife and the membrane, etc., so that the explosion-proof valve still has a small bursting pressure even after miniaturization.

[0016] Specifically, for working conditions such as battery packs, the temperature rises and falls slowly during normal use, and the air pressure changes naturally not much. The temperature of the battery pack often stops changing after it rises to a certain level, and the battery pack itself has a certain strength, and will not be damaged by a small increase in air pressure for a short period of time. Therefore, the requirements for the air permeability of the explosion-proof valve during daily use are not very high. However, once an abnormality occurs in the battery pack, the temperature inside it will rise significantly in a short period of time, and the air pressure will naturally change suddenly. At this time, higher requirements are placed on the air permeability of the explosion-proof valve, which needs to be able to respond quickly and produce a pressure relief effect after reaching the relevant bursting pressure.

[0017] Based on this, the present application controls the ratio of the effective working area of ​​the elastic membrane to the effective working area of ​​the breathable membrane to be 1 to 3, and cooperates with the special assembly method of the membrane assembly with the elastic membrane inside and the breathable membrane outside. On the one hand, it ensures that even after the explosion-proof valve is miniaturized, the elastic membrane has a sufficiently large working area, so that the elastic membrane with strong deformation ability can undergo a large deformation under a small air pressure (small bursting pressure), thereby cooperating with the piercing member inside the explosion-proof valve to blast and release pressure; on the other hand, it ensures that the breathable membrane inside the explosion-proof valve, which has already been miniaturized, has a sufficiently large working area, so as to meet the daily needs of waterproofing and breathability, and maintaining the balance of internal and external air pressure. More importantly, the elastic membrane in the present application has a large deformation amount before the explosion occurs, and the ratio of the areas of the two is controlled to be 1 to 3 and the breathable membrane ring is controlled to be arranged radially outside the elastic membrane. Not only can the breathable membrane ensure daily waterproof and breathable needs, but also sufficient space can be provided for the radial deformation of the elastic membrane (the ratio of the two is not greater than 3, the area of ​​the breathable membrane is not too small, and the space above the axial direction can be used for the radial deformation of the elastic membrane), thereby ensuring that the elastic membrane can be fully deformed and thus contact the puncture member to cause an explosion.

[0018] At the same time, the reasonable area ratio of the elastic membrane to the breathable membrane enables the elastic membrane to produce a large deformation even under a small air pressure. While controlling the area ratio of the elastic membrane to the breathable membrane, the present application controls the axial distance between the elastic membrane and the puncture member to be much larger than the conventional needle-pierced explosion-proof valve (CN218648096U clearly states that the distance between the two is not more than 1.2 mm, while the distance between the two in the present application is not less than 5 mm, which is significantly larger). The larger distance between the two greatly reduces the possibility of failure of the explosion-proof valve under vibration conditions. Of course, the present application also controls the axial distance between the elastic membrane and the puncture member to be no more than 20 mm, on the one hand to ensure that the explosion-proof valve still has a small bursting pressure after miniaturization (the deformation required for the explosion is not too high), and on the other hand to prevent the elastic membrane from being suppressed in radial deformation after excessive deformation, thereby affecting the stability of the explosion pressure relief (the area ratio of the elastic membrane to the breathable membrane determines that the space above the breathable membrane is limited).

[0019] In summary, by introducing a membrane assembly with a special structure into the explosion-proof valve, controlling the area ratio of the elastic membrane and the breathable membrane in the membrane assembly, and controlling the axial spacing between the elastic membrane and the piercing member, it is possible to ensure that the explosion-proof valve has a smaller burst pressure even after miniaturization. Even in special vibration conditions, the miniaturized explosion-proof valve in the present application is not prone to unexpected failure.

[0020] It is particularly important to note that the so-called miniaturization in this application refers to miniaturization on the original basis, and the specific size must not be less than a certain value. That is, the so-called miniaturization in this application is relative miniaturization, not absolute miniaturization.

[0021] In this application, the effective working area for an elastic membrane refers to an area that can be effectively deformed and is not fixed (such as adhesive fixation, welding fixation, snap fixation, etc.). For example, if the total diameter of the elastic membrane is 10 mm, an adhesive is provided around the outer edge and the width of the adhesive is 1 mm to bond and fix the elastic membrane, then the effective working area of ​​the elastic membrane is the area with a diameter of 8 mm that is not bonded and fixed. Similarly, for a breathable membrane, its effective working area is also the unfixed area.

[0022] When testing the bursting pressure of an explosion-proof valve, use the explosion-proof valve as the test sample and preset the gas source pressure. Then connect the explosion-proof valve to the gas source and observe whether an explosion occurs. Increase the preset pressure of the gas source by a gradient of 0.1 kPa and repeat the above operation until the explosion-proof valve bursts. Record the preset pressure of the gas source at this time, which is the bursting pressure of the explosion-proof valve.

[0023] Optionally, the thickness of the elastic membrane is 50-150 μm, and the ratio of the effective working area of ​​the elastic membrane to the thickness of the elastic membrane is 2.5-7.5 mm. 2 / μm.

[0024] Through the above technical solution, on the basis of the above, the present application further preferably controls the thickness of the elastic film to be 50-150 μm and controls the ratio of its effective area to thickness to be 2.5-7.5 mm 2 / μm, which can make the miniaturized explosion-proof valve have better explosion stability.

[0025] Specifically, as mentioned above, when the air pressure remains unchanged, the stress on the membrane is the same, so the deformation of the membrane is positively correlated with its effective area. However, in this application, the explosion-proof valve needs to be miniaturized, and the space reserved for the radial deformation of the elastic membrane is limited. Therefore, the deformation of the elastic membrane when it bursts should not be too large. Based on this, the initial thickness of the elastic membrane should not be too large (such as greater than 150μm), so as to avoid that under a smaller deformation, the deformed elastic membrane still has a large thickness when it contacts the piercing member and is difficult to burst and release pressure. Of course, the thickness of the elastic membrane should not be too small. On the one hand, it is necessary to avoid the elastic membrane from being too low in strength, and unexpected damage or even premature explosion under vibration conditions. On the other hand, it is necessary to avoid the elastic membrane from being too deformed under a smaller stress. After miniaturization, the space reserved for the deformation of the elastic membrane is limited. Once the deformation of the elastic membrane is limited, its bursting stability is difficult to guarantee (the deformation is limited, and the predictability of the deformation behavior is poor).

[0026] Furthermore, due to the high deformation capacity of the elastic membrane and the need for miniaturization, the inventors of the present application found that under the effective internal space and the determined knife-film spacing (i.e., the axial distance between the piercing element and the elastic membrane), by controlling the ratio of the effective working area of ​​the elastic membrane to the thickness of the elastic membrane to be 2.5 to 7.5 mm, 2 / μm, which can make the explosion-proof valve have further preferred bursting stability and good vibration tolerance. This is consistent with what was mentioned above. The area of ​​the elastic membrane directly affects the deformation of the elastic membrane, and the initial thickness of the elastic membrane also affects the deformation of the elastic membrane on the one hand. On the other hand, the initial thickness and deformation of the elastic membrane jointly determine the thickness of the elastic membrane when it contacts the piercing member, which naturally determines the difficulty of bursting the elastic membrane at this time. Therefore, controlling the ratio of the two within a certain range can avoid the decrease in vibration tolerance caused by the elastic membrane's effective area being too large and the initial thickness being too small (the ratio of the two is greater than 7.5), and can also avoid the decrease in bursting stability caused by the elastic membrane's effective area being too small and the initial thickness being too large (the ratio of the two is less than 2.5).

[0027] Optionally, the average deformation coefficient of the elastic film is (5-30)×10 -3 mm / kPa / mm 2 The average deformation coefficient refers to the ratio of the deformation height to the pressure difference on both sides of the elastic membrane per unit area when the pressure difference on both sides of the elastic membrane increases from 0 to 0.95 times the bursting pressure.

[0028] Through the above technical solution, for a certain membrane, if the air pressure remains unchanged, the stress is the same and the strain is the same; and the elastic membrane has a value of not less than 5×10 -3The deformation coefficient of the elastic membrane indicates that the elastic membrane has good deformation capacity, ensuring that after the explosion-proof valve is miniaturized, even if the effective area of ​​the elastic membrane is small, it can still undergo a large deformation under a small air pressure, and cooperate with the piercing member to explode and release pressure in time. -3 The deformation coefficient indicates that the deformation capacity of the elastic film still needs to be controlled within a certain range to prevent its strength from being too low and causing excessive swings during vibration. Even if the distance between the blade and the film in the present application is relatively large, there is still the possibility that the elastic film will come into contact with the piercing element and be damaged during vibration.

[0029] In the present application, the deformation coefficient testing method of the elastic membrane is to control the effective area diameter of the elastic membrane to 25 mm. The elastic membrane can be made into an explosion-proof valve for testing, or the elastic membrane can be fixed to a test fixture for testing. After connecting the explosion-proof valve or the test fixture to the air source, the pressure is increased at a rate of about 2 kPa / s until the explosion-proof valve is reached. When the pressure difference on both sides reaches 0.95 of the bursting pressure of the explosion-proof valve, the deformation height of the elastic membrane is recorded in real time, and based on the deformation height, its ratio to the test pressure and the effective area of ​​the elastic membrane is calculated, which is the deformation coefficient of the elastic membrane, which characterizes the deformation ability of the elastic membrane under the action of air pressure.

[0030] Optionally, the deformation coefficient of the elastic membrane when the pressure difference is 0 to 0.2 times the bursting pressure is smaller than the deformation coefficient when the pressure difference is 0.7 to 0.9 times the bursting pressure.

[0031] Through the above technical solution, the deformation coefficient of the elastic membrane under a smaller pressure is smaller than that under a larger pressure, which means that although the deformation height of the elastic membrane is positively correlated with the pressure difference on both sides, it tends to have a smaller deformation at a smaller pressure and a larger deformation at a larger pressure. Such an elastic membrane can ensure good vibration tolerance on the one hand, ensuring that it does not swing too much due to vibration, and on the other hand, it can ensure that when a larger pressure is reached (close to the bursting pressure), the elastic membrane undergoes a larger deformation to ensure bursting stability.

[0032] Special attention should be paid to the fact that, as mentioned above, during daily use of battery packs, the temperature changes relatively slowly, and the internal air pressure is not easy to reach the level close to the bursting pressure (such as greater than 0.7 times the bursting pressure), and the temperature often stops rising after reaching a certain level; the elastic membrane has a smaller deformation tendency at this stage, which can avoid damage to the elastic membrane during daily use due to the combined effects of air pressure changes and vibrations, and has a longer lifespan; at this stage, preventing the explosion-proof valve from prematurely bursting and failing is an issue that needs to be considered. When the internal air pressure quickly reaches the level close to the bursting pressure, the battery pack is obviously in an abnormally heated state, and the elastic membrane has a greater deformation tendency at this stage. Although there is a risk of premature bursting, it can ensure that the explosion-proof valve quickly bursts and releases pressure, reducing the risk of explosion; at this stage, preventing the explosion-proof valve from being unable to burst and release pressure is an issue that needs to be considered.

[0033] Optionally, an annular adhesive layer is bonded to the outer edge of the elastic membrane, and the elastic membrane is bonded to the inner edge of the breathable membrane through the annular adhesive layer; or, an annular adhesive layer is bonded to the outer edge of the elastic membrane, and the elastic membrane is bonded to the valve seat through the annular adhesive layer.

[0034] Through the above technical solution, the elastic membrane and the breathable membrane can be bonded into an integral membrane assembly, or they can be installed separately and bonded to the valve seat respectively, which does not hinder the membrane assembly from having a smaller bursting pressure after being miniaturized. Of course, for higher space utilization, it is preferred to bond the two into an integral membrane assembly.

[0035] Optionally, the ratio of the inner diameter of the annular rubber layer to the diameter of the elastic membrane is not less than 0.65; the ratio of the outer diameter to the inner diameter of the breathable membrane working area is 1.1-1.3; the ratio of the inner diameter of the breathable membrane working area to the outer diameter of the elastic membrane is 1-1.2.

[0036] Through the above technical solution, under the premise of miniaturization of the explosion-proof valve, the annular adhesive layer used to bond the elastic membrane should not occupy too large an area, so the inner diameter of the annular adhesive layer should not be greater than 0.65 times the diameter of the elastic membrane. Correspondingly, the ratio of the outer and inner diameters of the working area of ​​the breathable membrane should not be too small, so that it has sufficient air permeability to meet daily use, but the ratio of the two should not be too large to prevent it from occupying too much space; the ratio of the two is actually the width of the working area after removing the adhesive layer at its inner and outer edges. In addition, whether the elastic membrane and the breathable membrane are set as a whole or installed separately, the connection between the two should not be too far apart to obtain higher space utilization; of course, the breathable membrane should not be extended into the working area of ​​the elastic membrane, so as to avoid the breathable membrane from forming unnecessary pressure relief resistance when the elastic membrane explodes and releases pressure. Therefore, the ratio of the inner diameter of the working area of ​​the breathable membrane to the outer diameter of the elastic membrane should be controlled to be 1 to 1.2.

[0037] Optionally, the elastic membrane is bonded to the inner edge of the breathable membrane through the annular adhesive layer, and the elastic membrane is located on the side of the breathable membrane close to the valve cover; a limiting ring is provided in the valve seat, and the side wall of the limiting ring is connected to a plurality of connecting ribs to be connected to the inner wall of the valve seat, and the limiting ring is located on the side of the elastic membrane close to the valve cover and forms an axial limit on the outer edge of the elastic membrane.

[0038] Through the above technical solution, the elastic membrane is controlled to be located axially above the breathable membrane (the above refers to the side close to the valve cover), which can ensure that when the elastic membrane bulges upward and deforms, the breathable membrane located axially below does not hinder the deformation at the edge of the elastic membrane, so that the elastic membrane has stable explosion pressure relief performance.

[0039] On the basis of miniaturization of the explosion-proof valve, in order to improve the utilization rate of the limited space in the explosion-proof valve, the size of the annular adhesive layer bonding the elastic film needs to be properly controlled. However, the battery pack is charged and discharged frequently, and the elastic film inevitably needs to be frequently convex and deformed. When the annular adhesive layer is small in size, it is necessary to ensure that the elastic film has a low possibility of peeling to avoid failure of the explosion-proof valve due to peeling. The further set limit ring structure can form an axial limit on the outer edge of the elastic film to prevent its edge from peeling after frequent deformation.

[0040] Optionally, an annular protective layer is provided between the elastic membrane and the limiting ring, the protective layer is connected to the outer edge of the elastic membrane or to the end face of the limiting ring close to the elastic membrane, and the inner diameter of the protective layer is not greater than the inner diameter of the limiting ring.

[0041] Through the above technical solution, in order to make the explosion-proof valve have a smaller bursting pressure after miniaturization, the elastic membrane has a smaller strength and greater deformation capacity than the conventional breathable membrane, and is naturally more susceptible to damage. By setting an annular protective layer between the elastic membrane and the limit ring, and the inner diameter of the protective layer is not larger than the inner diameter of the limit ring, the hard limit ring can be isolated from the easily damaged elastic membrane, thereby greatly reducing the possibility of the elastic membrane directly contacting and rubbing with the limit ring when it is frequently convex and deformed, and even being subjected to the shear force of the edge of the limit ring, thereby improving the deformation stability and service life of the elastic membrane.

[0042] Optionally, the inner diameter of the limiting ring is larger than the diameter of the effective working area of ​​the elastic membrane; and / or the axial distance between the limiting ring and the elastic membrane is no more than 1 mm.

[0043] Through the above technical solution, as mentioned above, when the elastic membrane is deformed, it is not only deformed vertically upwards, but also inevitably deformed radially. At this time, it is necessary to avoid friction between it and the limiting ring, and even the possibility of damage caused by the shear force of the edge of the limiting ring. Therefore, in this application, the inner diameter of the limiting ring is controlled to be not less than the diameter of the effective working area of ​​the elastic membrane to avoid interference between the two.

[0044] In addition, the deformation characteristics of the elastic membrane are such that the closer it is to the outer edge, the smaller the radial deformation. The axial spacing between the control limit ring and the elastic membrane is no more than 1 mm, that is, the control limit ring is axially relatively close to the outer edge of the elastic membrane. This can significantly reduce the possibility of radial deformation of the elastic membrane interfering with the limit ring when it is deformed.

[0045] Optionally, the breathable membrane is annular; or, the breathable membrane is composed of a plurality of arcs and the plurality of breathable membranes are arranged at intervals in the circumferential direction.

[0046] Through the above technical solution, the breathable membrane can be an integral ring or composed of a plurality of arc-shaped separate breathable membranes, as long as it can meet the waterproof and breathable requirements during normal operation.

[0047] In summary, the present application includes at least one of the following beneficial technical effects:

[0048] 1. Based on the miniaturization of the explosion-proof valve, the present application introduces a special membrane assembly with an elastic membrane inside and a breathable membrane ring outside the explosion-proof valve, and cooperates with the area ratio, knife-membrane spacing and other restrictions, so that the explosion-proof valve still has a small bursting pressure even after miniaturization;

[0049] 2. By further limiting the thickness of the elastic membrane and the ratio of the effective working area of ​​the elastic membrane to the thickness of the elastic membrane, the miniaturized explosion-proof valve can have better explosion stability;

[0050] 3. By further controlling the average deformation coefficient range of the elastic film, and further controlling the deformation coefficient of the elastic film under low pressure to be smaller than the deformation coefficient under high pressure, the explosion-proof valve can still undergo a large deformation under a small air pressure after being miniaturized, but will not swing too much during vibration due to low strength, thereby causing its service life to be insufficient;

[0051] 4. By bonding the elastic membrane with the annular adhesive layer and introducing a limiting ring structure, the membrane assembly can not only have a further optimized space utilization rate, but also have good installation stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present application, in which the valve cover is in an open state.

[0053] Figure 2 It is a cross-sectional view of the overall structure of an embodiment of the present application.

[0054] Figure 3 It is a top view of an embodiment of the present application.

[0055] Figure 4 It is a schematic diagram of the structure of one of the membrane components of the embodiments of the present application.

[0056] Figure 5 It is a schematic diagram of the structure of the second membrane component of the embodiment of the present application.

[0057] Figure 6 It is a schematic diagram of the structure of the third membrane component of the embodiment of the present application.

[0058] Description of reference numerals:

[0059] 1. Valve body; 11. Valve seat; 12. Valve cover; 13. Pressure relief channel; 2. Composite explosion-proof membrane assembly; 21. Breathable membrane; 22. Elastic membrane; 23. Annular rubber layer; 24. Protective net; 3. Piercing piece; 41. Limiting ring; 42. Connecting rib; 5. Protective layer. DETAILED DESCRIPTION

[0060] Example 1

[0061] See also Figure 1-Figure 6 The embodiment of the present application discloses a miniaturized explosion-proof valve, including a valve body 1 and a composite explosion-proof membrane assembly 2. The valve body 1 is mainly used to install the composite explosion-proof membrane assembly 2 and connect it to equipment (such as storage tanks, pipelines, battery packs, etc.), and the composite explosion-proof membrane assembly 2 is mainly used for waterproof and breathable use during normal use and for explosion and pressure relief when the pressure difference between the inside and outside of the explosion-proof valve is too large.

[0062] See also Figure 1 and Figure 2 In this example, the valve body 1 includes a valve seat 11 as a mounting base, a valve cover 12 covering one end of the valve seat 11, and a pressure relief channel 13 communicating with the inner cavity of the valve seat 11 is provided inside the valve seat 11; the valve cover 12 can be installed on the valve seat 11 by snap connection, or by bonding, welding, etc., and the side wall of the valve seat 11 has an exhaust channel; a piercing member 3 is provided on the inner wall of the valve cover 12, and the end of the piercing member 3 facing away from the valve cover 12 has one or two sharp parts. The composite explosion-proof membrane assembly 2 is arranged in the valve seat 11 and separates the pressure relief channel 13 from the external environment.

[0063] See also Figure 4In this embodiment, the composite explosion-proof membrane assembly 2 includes a breathable membrane 21 that provides air permeability and an elastic membrane 22 that deforms after being compressed. Among them, the air permeability effect of the breathable membrane 21 is better than that of the elastic membrane 22, so that the breathable membrane 21 can maintain the air permeability effect of the explosion-proof valve during daily use, and the elastic membrane 22 can burst when the pressure difference between the pressure relief channel 13 and the external environment reaches a preset bursting pressure, thereby meeting the explosion-proof effect of the explosion-proof valve. Among them, the breathable membrane 21 is annular, and the side of the outer edge of the breathable membrane 21 away from the valve cover 12 is bonded to the valve seat 11 by an adhesive. Of course, on the premise of meeting daily ventilation needs, the breathable membrane 21 can also be arranged in an array and installed in a split manner. The elastic membrane 22 is located radially inside the breathable membrane 21 and between the breathable membrane 21 and the valve cover 12 . An annular adhesive layer 23 is bonded to the outer edge of the elastic membrane 22 away from the valve cover 12 . The elastic membrane 22 is bonded to the inner edge of the breathable membrane 21 via the annular adhesive layer 23 .

[0064] The elastic membrane 22 may be made of elastic materials such as silicone, latex, and PDMS (polydimethylsiloxane). Specifically, in this embodiment, the elastic membrane 22 is made of a PDMS membrane with a thickness of 98 μm; the breathable membrane 21 is made of a PTFE membrane.

[0065] In this embodiment, the composite explosion-proof membrane assembly 2 may further include a protective net 24. The installation method of the protective net 24 may be as follows: Figure 5 , annular adhesive is provided on both sides of the outer edge of the protective net 24, one side of the adhesive is used to bond with the side of the inner edge of the air permeable membrane 21 away from the valve cover 12, and the other side of the adhesive is used to bond with the valve seat 11. Of course, the installation method of the protective net 24 can be as follows Figure 6 The outer edges of the protective net 24 are bonded to the outer edges of the breathable membrane 21 and the valve seat 11 by adhesive. The protective net 24 can support the elastic membrane 22 and / or the breathable membrane 21 when the explosion-proof valve is wading, thereby reducing the possibility of friction damage between the elastic membrane 22 and the valve seat 11.

[0066] See also Figure 3, a limiting ring 41 is also provided in the valve seat 11 for limiting the outer edge of the elastic membrane 22. The outer peripheral wall of the limiting ring 41 has a plurality of connecting ribs 42 integrally formed therewith, and the end of the connecting rib 42 away from the limiting ring 41 is fixedly connected to the valve seat 11. The limiting ring 41 is located on the side of the elastic membrane 22 close to the valve cover 12. When the elastic membrane 22 bulges toward the valve cover 12 under the action of the relatively large internal air pressure, the limiting ring 41 limits the outer edge of the elastic membrane 22 to prevent the outer edge of the elastic membrane 22 from being bonded and peeled off and failing. In order to prevent the limiting ring 41 from hindering the deformation of the elastic membrane 22, thereby affecting the bursting stability of the explosion-proof valve, the inner diameter of the limiting ring 41 needs to be appropriately larger than the diameter of the effective working area of ​​the elastic membrane 22. Furthermore, in order to prevent the limiting ring 41 from hindering the radial deformation of the elastic membrane 22, the limiting ring 41 should not be too far away from the elastic membrane 22, and the axial distance between the two should be controlled to be no more than 1 mm.

[0067] See also Figure 4 In order to avoid the wear caused by direct contact between the soft elastic membrane 22 and the hard limiting ring 41, an annular protective layer 5 is provided between the elastic membrane 22 and the limiting ring 41. The protective layer 5 is a conventional hard material, such as a hard polymer material PET. In this embodiment, the protective layer 5 is bonded to the outer edge of the elastic membrane 22 by an adhesive, and the protective layer 5 and the limiting ring 41 are in contact with each other to avoid the axial distance between the limiting ring 41 and the elastic membrane 22 being too large; the adhesive cooperates with the protective layer 5 to appropriately space the elastic membrane 22 and the limiting ring 41. Of course, the protective layer 5 can play the protective effect regardless of whether it is connected to the limiting ring 41 or the elastic membrane 22. In order to ensure a good protective effect, the inner diameter of the protective layer 5 should be appropriately smaller than the inner diameter of the limiting ring 41. Of course, in order to avoid it affecting the deformation of the elastic membrane 22, the inner diameter of the protective layer 5 should not be smaller than the diameter of the effective working area of ​​the elastic membrane 22.

[0068] Specifically, in this embodiment, the diameter of the elastic membrane 22 is 30 mm, the diameter of the effective working area is 25 mm, the width of the annular rubber layer 23 is 2.5 mm, and the outer diameter of the annular rubber layer 23 is the same as the diameter of the elastic membrane 22. The inner diameter of the breathable membrane 21 is the same as the diameter of the effective working area of ​​the elastic membrane 22, both of which are 25 mm; while the inner diameter of the effective working area of ​​the breathable membrane 21 is the same as the diameter of the elastic membrane 22, both of which are 30 mm; the outer diameter of the effective working area of ​​the breathable membrane 21 is controlled to be 36 mm. That is, in this embodiment, the ratio of the area of ​​the effective working area of ​​the elastic membrane 22 to the area of ​​the effective working area of ​​the breathable membrane 21 is about 1.6, and the ratio of the area of ​​the effective working area of ​​the elastic membrane 22 to its thickness is about 5.0 mm 2 The ratio of the inner diameter of the annular rubber layer 23 to the diameter of the elastic membrane 22 is about 0.83, and the ratio of the outer diameter to the inner diameter of the effective working area of ​​the air permeable membrane 21 is 1.2.

[0069] After testing, the explosion pressure of the explosion-proof valve in the embodiment is about 6.4 kPa, and the average deformation coefficient is about 12.6×10 -3 mm / kPa / mm 2 .

[0070] Embodiment 2-5

[0071] The main difference between Example 2-5 and Example 1 is that various parameters of the explosion-proof valve, especially the membrane assembly, are appropriately adjusted, as shown in Table 1 for details.

[0072] Comparative Example

[0073] Comparative Example 1

[0074] The main difference between Comparative Example 1 and Example 1 is that, on the basis of the unchanged overall radial dimensions of the explosion-proof valve, especially the membrane assembly, on the one hand, the explosion-proof valve is controlled to have a larger knife-membrane spacing, specifically controlled to be 25 mm; on the other hand, the elastic membrane 22 is controlled to have a relatively small effective area, specifically controlled to have a ratio of the effective working area of ​​the elastic membrane 22 to the effective working area of ​​the air-permeable membrane 21 to be 0.5. The selection of the elastic membrane 22 and the air-permeable membrane 21 is exactly the same as that of Example 1, as shown in Table 1 for details.

[0075] Comparative Example 2

[0076] The main difference between Comparative Example 2 and Example 1 is that, on the basis of the unchanged overall radial dimensions of the explosion-proof valve, especially the composite explosion-proof membrane assembly 2, the composite explosion-proof membrane assembly 2 in Example 1 is replaced with a PTFE membrane, and the diameter of the PTFE breathable membrane 21 is the same as the outer diameter of the breathable membrane 21 in Example 1, and the membrane selection is also the same. In order to ensure that the explosion-proof valve can be exploded smoothly, the knife-membrane spacing of the explosion-proof valve is set to 1.5mm. At this time, the air permeability of the explosion-proof valve is 4514ml / min under the test pressure of 1kPa. The explosion pressure of the explosion-proof valve in this comparative example was tested to be about 16kPa.

[0077] Comparative Example 3

[0078] The main difference between Comparative Example 3 and Comparative Example 2 is that a relatively high porosity PTFE breathable membrane 21 is selected, and the knife-membrane distance is adjusted to 0.8 mm. At this time, the air permeability of the explosion-proof valve is 6574 ml / min under a test pressure of 1 kPa. The bursting pressure of the explosion-proof valve in this comparative example is tested to be about 11.3 kPa.

[0079] Comparative Example 4

[0080] The main difference between Comparative Example 3 and Comparative Example 2 is that a relatively high porosity PTFE breathable membrane 21 is selected. At this time, the air permeability of the explosion-proof valve is 8465 ml / min under a test pressure of 1 kPa. The bursting pressure of the explosion-proof valve in this comparative example is tested to be about 10.9 kPa.

[0081] After testing, the explosion-proof valves in Examples 1-5 have relatively small bursting pressures at the same size and can pass the vibration test. Although the explosion-proof valve in Comparative Example 1 also uses a membrane assembly structure with an elastic membrane 22 inside and a breathable membrane 21 surrounding it, its excessively large knife-membrane spacing and too small area ratio between the two ultimately make it have a larger bursting pressure. Furthermore, the explosion-proof valve in Comparative Example 2 can pass the vibration test under the premise of the same radial size, but its bursting pressure is significantly greater; although Comparative Examples 3 and 4 reduce the bursting pressure to a certain extent by further increasing the porosity of the PTFE breathable membrane 21, they do not pass the vibration test; and especially Comparative Example 4, which has the largest porosity, even leaks when the wading depth is 1m (there is no leakage in the other embodiments and comparative examples).

[0082] Table 1 Parameters of various embodiments and comparative examples

[0083]

[0084] The performance test method is as follows:

[0085] 1. Blasting performance test

[0086] 1.1 Burst pressure

[0087] When testing the bursting pressure of the explosion-proof valve, the explosion-proof valve in each embodiment and comparative example is used as a test sample, and the gas source pressure is preset. Then the explosion-proof valve is connected to the gas source to observe whether an explosion occurs. The preset pressure of the gas source is increased with a gradient of 0.1 kPa. The above operation is repeated until the explosion-proof valve explodes. The preset pressure of the gas source at this time is recorded, which is the bursting pressure of the explosion-proof valve.

[0088] 1.2 Deformation coefficient

[0089] The effective working area diameter of the elastic membrane is controlled to be 25mm. The elastic membrane can be made into an explosion-proof valve for testing, or the elastic membrane can be fixed to a test fixture for testing. After connecting the explosion-proof valve or the test fixture to the air source, the pressure is increased at a rate of about 2kPa / s until it reaches the explosion-proof valve. When the pressure difference on both sides reaches 0.95 of the bursting pressure of the explosion-proof valve, the deformation height of the elastic membrane is recorded in real time, and based on the deformation height, its ratio to the test pressure and the effective area of ​​the elastic membrane is calculated, which is the deformation coefficient of the elastic membrane, which characterizes the deformation ability of the elastic membrane under the action of air pressure.

[0090] It is important to note that when testing the bursting pressure of the elastic membrane, it is necessary to use the test method of presetting the gas source pressure and then connecting the explosion-proof valve to simulate the working condition of rapid increase in gas pressure when an abnormality occurs; and when testing the deformation coefficient of the elastic membrane, it is necessary to use the test method of first connecting the gas source and then slowly increasing the gas source pressure to simulate the working condition of slow increase in gas pressure during normal operation. In addition, the deformation of the elastic membrane under the conditions of rapid pressure increase and slow pressure increase is not exactly the same. For example, when testing the deformation coefficient, the test condition of slow pressure increase gives the elastic membrane relatively ample deformation time, so it often has a larger deformation.

[0091] 2. Vibration test

[0092] The test method of vibration test refers to ISO-16750-3 Environmental conditions and tests for electrical and electronic equipment of road vehicles Part 3: Mechanical loads; specifically, sinusoidal vibration: frequency is (100~440) Hz, maximum acceleration is 60m / s2, and test duration is 42h; random vibration: frequency is (10~2000) Hz, PSD is 10(m / s2)2Hz, and test duration is 42h. After the vibration test, the bursting pressure of the explosion-proof valve is tested. If the bursting pressure decreases before and after the vibration test, it is considered that the vibration test has not been passed.

[0093] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A miniaturized explosion-proof valve, characterized in that: include: The valve body comprises a valve seat as a mounting base and a valve cover connected to one end of the valve seat, a pressure relief passage communicating with an inner cavity of the valve seat is provided inside the valve body, and a piercing member is provided on the inner surface of the valve cover; A composite explosion-proof membrane assembly is arranged in the valve seat and isolates the pressure relief channel from the inner cavity of the valve seat, comprising a breathable membrane that provides air permeability and an elastic membrane that deforms after being pressurized, wherein the breathable membrane is arranged in a ring outside the elastic membrane; The distance between the piercing element and the elastic membrane is 5-20 mm, the ratio of the effective working area of ​​the elastic membrane to the effective working area of ​​the breathable membrane is 1-3, and the bursting pressure of the explosion-proof valve is 3-10 kPa.

2. A miniaturized explosion-proof valve according to claim 1, characterized in that: The thickness of the elastic film is 50-150 μm, and the ratio of the effective working area of ​​the elastic film to the thickness of the elastic film is 2.5-7.5 mm 2 / μm.

3. A miniaturized explosion-proof valve according to claim 1, characterized in that: The average deformation coefficient of the elastic film is (5-30)×10 -3 mm / kPa / mm 2 The average deformation coefficient refers to the ratio of the deformation height to the pressure difference on both sides of the elastic membrane per unit area when the pressure difference on both sides of the elastic membrane increases from 0 to 0.95 times the bursting pressure.

4. A miniaturized explosion-proof valve according to claim 1, characterized in that: The deformation coefficient of the elastic membrane when the pressure difference is 0 to 0.2 times the bursting pressure is smaller than the deformation coefficient when the pressure difference is 0.7 to 0.9 times the bursting pressure.

5. The miniaturized explosion-proof valve according to claim 1, characterized in that: The outer edge of the elastic membrane is bonded with an annular adhesive layer, and the elastic membrane is bonded to the inner edge of the breathable membrane through the annular adhesive layer; or, the outer edge of the elastic membrane is bonded with an annular adhesive layer, and the elastic membrane is bonded to the valve seat through the annular adhesive layer.

6. A miniaturized explosion-proof valve according to claim 5, characterized in that: The ratio of the inner diameter of the annular rubber layer to the diameter of the elastic membrane is not less than 0.65; the ratio of the outer diameter to the inner diameter of the working area of ​​the breathable membrane is 1.1-1.3; the ratio of the inner diameter of the working area of ​​the breathable membrane to the outer diameter of the elastic membrane is 1-1.

2.

7. A miniaturized explosion-proof valve according to claim 5, characterized in that: The elastic membrane is bonded to the inner edge of the breathable membrane through the annular adhesive layer, and the elastic membrane is located on the side of the breathable membrane close to the valve cover; a limiting ring is provided in the valve seat, and a side wall of the limiting ring is connected to a plurality of connecting ribs to be connected to the inner wall of the valve seat, and the limiting ring is located on the side of the elastic membrane close to the valve cover and forms an axial limit on the outer edge of the elastic membrane.

8. A miniaturized explosion-proof valve according to claim 7, characterized in that: An annular protective layer is provided between the elastic membrane and the limiting ring. The protective layer is connected to the outer edge of the elastic membrane or to the end face of the limiting ring close to the elastic membrane. The inner diameter of the protective layer is not greater than the inner diameter of the limiting ring.

9. A miniaturized explosion-proof valve according to claim 7, characterized in that: The inner diameter of the limiting ring is larger than the diameter of the effective working area of ​​the elastic membrane; and / or the axial distance between the limiting ring and the elastic membrane is no larger than 1 mm.

10. The miniaturized explosion-proof valve according to claim 1, characterized in that: The breathable membrane is annular; or, the breathable membrane is composed of a plurality of arcs and the plurality of breathable membranes are arranged at intervals in the circumferential direction.

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