Explosion-proof valve

Abstract

The invention provides an anti-explosion valve which comprises a valve body and a valve cover connected to one end of the valve body, a supporting plate is arranged in the valve body, and the supporting plate is provided with an air hole; the membrane assembly is arranged on the end face, facing the valve cover, of the supporting plate, comprises a waterproof elastic membrane and a waterproof breathable membrane and covers the breathable hole; the elastic film is located in the center area of the supporting plate, and the waterproof breathable film is arranged on the outer side of the elastic film in a surrounding mode. The waterproof elastic membrane and the waterproof breathable membrane are combined together, the elastic membrane is located in the center area of the supporting plate, the waterproof breathable membrane is arranged on the outer side of the elastic membrane in a surrounding mode, the membrane assembly combination body is formed, the membrane assembly combination body is applied to the anti-explosion valve, the membrane assembly combination body has creativity, and the membrane assembly combination body can be applied to the anti-explosion valve. And a new solution thought is provided for giving consideration to the good waterproofness and the rapid pressure relief function of the anti-explosion valve.

Description

Technical Field

[0001] The invention relates to the field of explosion-proof technology, and in particular to an explosion-proof valve capable of achieving good waterproofness and rapid pressure relief. Background Art

[0002] An explosion-proof valve is a pressure relief device used for equipment or pipelines containing flammable gases or flammable substances in dust-proof systems. In new energy vehicles, the battery pack is a vital component, and the use of the battery pack will generate heat, which will increase the air pressure inside the battery pack. When the temperature of the battery pack rises abnormally quickly, the internal air pressure will also rise rapidly, which may cause damage to internal components or even exceed the designed sealing capacity of the battery pack and cause an explosion. In order to prevent the internal air pressure of the battery pack from being too high, an explosion-proof valve is usually installed on the battery pack to maintain the balance of internal and external air pressure. When the air pressure in the battery pack increases sharply, the breathable membrane in the explosion-proof valve will deform, and when the air pressure reaches the preset limit value (generally referred to as the bursting pressure), the breathable membrane inside the explosion-proof valve will rupture, quickly balancing the internal and external air pressures to achieve the purpose of pressure relief.

[0003] Common explosion-proof valves currently have a waterproof breathable membrane, and PTFE microporous membrane is often used as the waterproof breathable membrane. The microporous structure in the PTFE microporous membrane meets the ventilation requirements during normal use, and when the air pressure reaches the preset limit value, the PTFE microporous membrane is punctured by a puncturing member or other structure to achieve a pressure relief effect. For example, in the Chinese utility model patent with the 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 breathable membrane is arranged in the pressure relief channel of the valve body, and the waterproof breathable membrane is a PTFE microporous membrane; a puncturing member with a sharp portion facing the waterproof breathable membrane is arranged on the valve cover, and the fixing portion of the puncturing member is arranged on the valve cover, and a notch is opened on the sharp portion of the puncturing member to form multiple tip portions.

[0004] Since the emergence of such explosion-proof valves and their application in battery packs, there has always been a problem that good waterproofness under normal working conditions and rapid pressure relief function under bursting pressure cannot be achieved at the same time. This problem is a technical difficulty that technicians in this field have always been eager to solve but have never been successful. The reason is that the single PTFE membrane currently used cannot simultaneously take into account good waterproofness and rapid pressure relief performance.

[0005] Waterproof and breathable are basic functions that explosion-proof valves must provide, otherwise they cannot meet the waterproof and breathable requirements of equipment such as battery packs under normal working conditions. Under normal working conditions, the PTFE membrane plays a waterproof and breathable function to prevent water from entering the battery pack. At the same time, to balance the pressure inside and outside the equipment, it must be able to provide a certain amount of air permeability. Especially the waterproof requirement, it is necessary to ensure that water will not enter the battery pack and cause damage to the battery pack when the battery pack is used in water, etc., which puts higher requirements on the waterproof performance of the PTFE membrane.

[0006] To improve the waterproof performance, the PTFE membrane is required to have a larger density and / or thickness to increase water resistance, reduce the possibility of water leakage, and deteriorate the air permeability. The larger density and / or thickness make the PTFE membrane have higher strength. The high-strength PTFE membrane produces less deformation under the stress generated by the bursting pressure. In addition, the PTFE membrane itself has a relatively high strength, which makes it difficult to be punctured, or even if it can be punctured, the puncture is very small, and the purpose of rapid pressure relief cannot be achieved.

[0007] Based on this, this application is filed. Summary of the invention

[0008] In order to solve the problem that the existing explosion-proof valve cannot achieve both good waterproofness and rapid pressure relief, the following technical solutions are proposed:

[0009] An explosion-proof valve comprises a valve body and a valve cover connected to one end thereof, wherein a support plate is arranged in the valve body and the support plate has air holes;

[0010] It also includes a membrane assembly disposed on the end surface of the support plate facing the valve cover, the membrane assembly includes a waterproof elastic membrane and a waterproof breathable membrane, covering the breathable hole;

[0011] The elastic membrane is located in the central area of ​​the support plate, and the waterproof and breathable membrane is arranged around the outer side of the elastic membrane.

[0012] Under normal working conditions, the temperature of the battery pack does not rise or fall very fast, nor does it form a high internal and external pressure difference. In addition, the battery pack has a certain strength and will not be damaged by a small increase in air pressure in a short period of time. Therefore, the requirements for the air permeability of the explosion-proof valve in daily use are not very high, and ordinary PTFE membranes can meet its normal air permeability requirements. However, once an abnormality occurs in the battery pack, the temperature inside it will rise significantly in a short period of time, and the internal and external pressure difference will also increase rapidly. At this time, higher requirements are placed on the air permeability of the explosion-proof valve, which needs to respond quickly and release pressure quickly after reaching the bursting pressure.

[0013] In the explosion-proof valve provided by the present application, the membrane assembly covering and sealing the vent hole includes a waterproof elastic membrane and a waterproof breathable membrane. Under normal use conditions of the battery pack, the waterproof breathable membrane plays a role in balancing the internal and external pressures, and prevents the elastic membrane from excessively bulging and expanding upwards under the internal and external pressure difference that is much smaller than the bursting pressure, thereby preventing the elastic membrane from being in a state of large expansion and stretching for a long time, protecting the elastic membrane, and because the elastic membrane is also waterproof, it plays a waterproof function together with the waterproof breathable membrane, preventing liquid water from entering the interior of the explosion-proof valve and protecting the battery pack;

[0014] On this basis, the elastic membrane is arranged in the central area of ​​the support plate, and the waterproof and breathable membrane is arranged around the outside of the elastic membrane. The elastic membrane and the waterproof and breathable membrane are arranged in this way, which makes full use of the space inside the explosion-proof valve and makes the explosion-proof valve structure more compact; more importantly, the elastic membrane is located in the center and is separated from the inner wall of the valve body by a certain distance to prevent it from abutting against the inner wall of the valve body after being compressed and bulging upward, and being unable to continue to expand upward, or expanding into an abnormal shape, resulting in the elastic membrane not being able to burst normally when the internal and external pressure difference reaches the bursting pressure, and an accident may occur; and separating the elastic membrane from the inner wall of the valve body can also prevent it from rupturing prematurely due to abutting against and hitting the inner wall of the valve body after expansion and bulging, ensuring that under the internal and external pressure difference lower than the bursting pressure, the elastic membrane can remain intact, the membrane assembly can work normally, and reliable waterproof and breathable performance is provided.

[0015] When the battery pack is abnormal, the pressure difference between the inside and outside of the membrane assembly will increase in a very short time and reach the bursting pressure. The expansion and bulging of the elastic membrane can be roughly divided into two stages:

[0016] In the first stage, the internal and external pressure difference of the membrane assembly is still relatively small, and there is still a certain gap with the bursting pressure, but the internal and external pressure difference is increasing, and the elastic membrane expands and bulges upward toward the valve cover under the action of the internal and external pressure difference. The elastic membrane is stretched, the thickness decreases, and becomes thinner. When the internal and external pressure difference approaches the bursting pressure of the explosion-proof valve, the elastic membrane has expanded greatly, similar to a bulging balloon, and the elastic membrane is very tight and extremely thin;

[0017] In the second stage, the internal and external pressure difference continues to increase from a value close to the bursting pressure, and when it reaches the bursting pressure, the elastic membrane that has been stretched very thin and very tight will burst in an instant, forming a large breach, and the gas in the valve will quickly spray outward, thereby achieving rapid pressure relief. After the elastic membrane forms a breach, the gas spraying outward at a very fast speed will form an airflow to impact the elastic membrane, and the middle area has the greatest impact force, causing the breach to be further torn. The most obvious effect is that after the elastic membrane bursts, the air flow rate of the entire explosion-proof valve is greatly increased.

[0018] Of course, the elastic membrane can also be exploded with the help of external force, such as a piercing structure with a sharp part; it can also be exploded by reaching its mechanical limit through its own large deformation; of course, local weak points can be further set on the elastic membrane to ensure that it explodes after reaching a certain deformation.

[0019] On the one hand, the membrane assembly composed of a waterproof elastic membrane and a waterproof breathable membrane is applied to the explosion-proof valve, which enables the explosion-proof valve to have both good waterproofness and rapid pressure relief function, which meets the application scenario requirements of the explosion-proof valve and solves the technical problems that have always existed in the field of explosion-proof valve technology but have been difficult to solve.

[0020] On the other hand, since the conventional practice has always been to apply a single PTFE membrane to explosion-proof valves and set a puncture piece on the valve cover, the present application proposes to combine a waterproof elastic membrane and a waterproof breathable membrane together, and the elastic membrane is located in the central area of ​​the support plate, and the waterproof breathable membrane is surrounded by the outside of the elastic membrane to form a membrane component assembly, and the membrane component assembly is applied to explosion-proof valves. The proposal of the membrane component assembly itself is groundbreaking and provides a new solution for taking into account both the good waterproofness and rapid pressure relief function of explosion-proof valves.

[0021] Furthermore, a support net is provided between the membrane assembly and the air vents, and the support net at least separates the elastic membrane from the support plate.

[0022] When the external pressure of the membrane assembly is higher than the internal pressure, the elastic membrane will sink into the air holes, which may damage the elastic membrane and cause the waterproof performance of the elastic membrane to deteriorate; or, when the elastic membrane is impacted by liquid water, it will also sink downward into the air holes, causing wear; the elastic membrane and the support plate are separated by a support net, that is, the elastic membrane and the air holes are separated, so that no matter it is subjected to external pressure or impact of liquid water, under the support and holding action of the support net, the depression of the elastic membrane is limited, and it is basically kept flat, avoiding wear and tear, and can remain intact, ensuring the overall waterproof performance of the membrane assembly so that the membrane assembly can work normally.

[0023] Furthermore, when the pressure difference between the inside and outside of the elastic membrane is less than 85% of the bursting pressure of the explosion-proof valve, the increment of the height of the elastic membrane bulging toward the valve cover per unit increment of the internal and external pressure difference is K1; when the ratio of the internal and external pressure difference of the elastic membrane to the bursting pressure of the explosion-proof valve is between 85% and 100%, the increment of the height of the elastic membrane bulging toward the valve cover per unit increment of the internal and external pressure difference is K2, satisfying: 1.5≤K1≤4.5, and K2 / K1=1.1~5, wherein the unit of the height of the elastic membrane bulging toward the valve cover is mm, and the unit of the internal and external pressure difference of the elastic membrane is kPa.

[0024] It is generally believed that when the elastic membrane is an elastic material, its stress and strain roughly conform to Hooke's law, that is, strain is proportional to stress. Specifically for the elastic membrane of the present application, during use, the degree of deformation should increase with the increase of the pressure difference on both sides, and be roughly proportional, and the elastic membrane undergoes a relatively regular elastic deformation. However, the inventors of the present application unexpectedly discovered that on the basis of selecting an elastic membrane, if an elastic membrane that undergoes a greater deformation after reaching a certain pressure difference is preferably used (that is, after reaching a certain pressure difference, it does not only undergo regular elastic deformation, but may exceed its elastic limit, so the same stress can produce a greater strain), the explosion-proof valve of the present application can have better vibration tolerance under low pressure conditions and better burst pressure relief stability under high pressure conditions. Specifically, in a smaller range of internal and external pressure differences, the K value is smaller; when the internal and external pressure differences are close to the burst pressure, the K value is larger, which can not only prevent the elastic membrane from forming a large bulge prematurely, so as to avoid the elastic membrane from being in a large bulge state for a long time and forming damage, but also ensure rapid bursting in a very short time after reaching the burst pressure.

[0025] This is mainly because the application scenarios of equipment such as battery packs often have large vibrations. On this basis, there are actually two working conditions for explosion-proof valves, and the performance requirements for explosion-proof valves in different working conditions are not the same. The first working condition is that when the battery pack is in normal use, the pressure rises slowly and the pressure difference on both sides is small (not greater than 85% of the bursting pressure). In this working condition, it is necessary to ensure that the deformation caused by the vibration is superimposed on the deformation caused by the pressure difference on both sides, and it is not easy to cause the elastic membrane to burst and fail prematurely and affect the service life of the explosion-proof valve. At this time, it is hoped that the elastic membrane has a relatively small K, and the stress is not easy to cause excessive strain; the other working condition is that the battery pack is abnormal, the internal pressure rises rapidly, and the pressure difference on both sides is large. In this working condition, the primary task is to ensure the safety of the battery pack by the explosion of the elastic membrane, rather than pursuing the service life of the explosion-proof valve. Therefore, it is hoped that the elastic membrane can quickly produce a large deformation under a large pressure difference (close to the bursting pressure, greater than 85% of the bursting pressure), that is, it is hoped that the elastic membrane has a relatively large K, and the stress can cause a large strain.

[0026] In a relatively small range of internal and external pressure differences, the K value is slightly smaller, that is, when the internal and external pressure difference is less than 85% of the bursting pressure, K1 takes a value between 1.5 and 4.5, so that in a range of internal and external pressure differences far from the bursting pressure, the elastic membrane bulges upward with a unit internal and external pressure difference increment. The increment is small, which can prevent the elastic membrane from forming a large bulge too early, and prevent the elastic membrane from being in a large bulge state for a long time, that is, prevent the elastic membrane from being in a large stretch state for a long time, reduce the damage to the elastic membrane, ensure its integrity, and then extend the service life of the elastic membrane to prevent it from bursting early;

[0027] When the internal and external pressure difference is close to the bursting pressure, the K value is larger. When the ratio of the internal and external pressure difference to the bursting pressure of the explosion-proof valve is 85% to 100%, K2 is 1.1 to 5 times of K1. That is to say, in the internal and external pressure difference range close to the bursting pressure, as the internal and external pressure difference further increases, the elastic membrane bulges upward with a larger increment per unit internal and external pressure difference increment, and the volume expands faster. When the internal and external pressure difference reaches the bursting pressure, the elastic membrane bursts quickly to form a large breach, and the gas bound inside it sprays out quickly, thereby realizing the rapid pressure relief function.

[0028] Furthermore, the bursting height of the elastic membrane is H. When the pressure difference between the inside and outside of the elastic membrane is 70% of the bursting pressure of the explosion-proof valve, the height h1 of the elastic membrane bulging toward the valve cover satisfies: h1 / H=0.2-0.7.

[0029] When the internal and external pressure difference reaches 70% of the bursting pressure, the height h1 of the elastic membrane bulging upward is not less than 20% of the bursting height H, so that when the internal and external pressure difference continues to increase and reaches the bursting pressure, the elastic membrane continues to bulge upward, and the bulging height h1 can reach the bursting height H. The volume of the elastic membrane expands large enough and is in a stretched and taut state. It bursts at the moment the internal and external pressure difference reaches the bursting pressure, and the gas instantly sprays out to release the pressure quickly.

[0030] It is further limited that when the internal and external pressure difference reaches 70% of the bursting pressure, the upward bulging height h1 of the elastic membrane shall not be greater than 70% of the bursting height H, so as to avoid the elastic membrane from forming a bulge of excessive height under the internal and external pressure difference far away from the bursting pressure. Since the equipment is in a vibrating working environment, the elastic membrane may burst prematurely due to the vibration if it bulges too much prematurely.

[0031] Furthermore, the bursting height of the elastic membrane is H. When the pressure difference between the inside and outside of the elastic membrane is 85% of the bursting pressure of the explosion-proof valve, the height h2 of the elastic membrane bulging toward the valve cover satisfies h2 / H≥0.8.

[0032] When the pressure difference between the inside and outside of the elastic membrane reaches 85% of the bursting pressure, the ratio of its bulging height h2 to the bursting height H is not less than 0.8, that is, when the internal and external pressure difference is close to the bursting pressure, the bulging height of the elastic membrane is also close to the bursting height, to ensure that when the internal and external pressure difference continues to increase and reaches the bursting pressure, the bulging height h2 of the elastic membrane reaches the bursting height H, and at the moment when the internal and external pressure difference reaches the bursting pressure, it quickly blasts and bursts to achieve pressure relief.

[0033] 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. At this time, the elastic membrane is instantly deformed; 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. At this time, the elastic membrane is fully deformed. 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 sufficient deformation time, so it often has a larger deformation. Therefore, when h2 is measured at 85% of the bursting pressure under slow pressure increase conditions, it is likely to be greater than the bursting height H, but it does not mean that the explosion-proof valve has burst at 85% of the bursting pressure under instantaneous pressure increase conditions.

[0034] Furthermore, the air holes include a first air hole and a second air hole that are spaced apart, the first air hole is located in the central area of ​​the support plate, the second air hole is surrounded on the outside of the first air hole, the elastic membrane covers the first air hole, and the waterproof breathable membrane covers the second air hole.

[0035] The first air hole located in the center corresponds to the elastic membrane, and the second air hole located on the outside corresponds to the waterproof breathable membrane. The second air hole is used to achieve ventilation under normal working conditions and balance the internal and external pressures. When the waterproof breathable membrane cannot discharge the gas inside the membrane assembly in time, the pressure inside the membrane assembly increases, forming an internal and external pressure difference, and the internal gas pushes the elastic membrane upward through the first air hole, and the elastic membrane bulges upward and increases in volume. When the internal and external pressure difference reaches the bursting pressure, the height to which the elastic membrane bulges upward reaches the bursting height, and it explodes instantly and releases pressure quickly.

[0036] Furthermore, the support plate includes a first area where the first air holes are arranged and a second area for fixing the outer edge of the waterproof and breathable membrane;

[0037] The area of ​​the first air hole is greater than the area of ​​the second air hole;

[0038] The first zone has an annular zone located in the outer circle, which is used to fix the outer edge of the elastic membrane and the inner edge of the waterproof breathable membrane. The outer wall of the annular zone is connected to the inner wall of the second zone through a plurality of connecting blocks arranged at circumferential intervals. The adjacent connecting blocks and the outer wall of the annular zone and the inner wall of the second zone are surrounded to form a second air hole.

[0039] The annular area of ​​the first zone outer ring and the second zone of the support plate respectively fix and support the inner edge and outer edge of the waterproof breathable membrane, and the annular area of ​​the first zone outer ring fixes and supports the outer edge of the elastic membrane, so that the waterproof breathable membrane and the elastic membrane can play their respective functions, and it is also conducive to the realization of the good waterproof performance and rapid pressure relief function of the membrane assembly. The area of ​​the first air hole is larger than the area of ​​the second air hole, and correspondingly, the area of ​​the elastic membrane is also larger. When the pressure difference between the inside and outside is greater, the deformation becomes larger and the bulge height is higher. More importantly, when the elastic membrane is breached, the gas in the valve can be ejected out faster.

[0040] Furthermore, it also includes a limiting ring located on the side of the elastic membrane facing the valve cover, the outer wall of which is connected to the inner wall of the valve body through a plurality of connecting ribs arranged at intervals in the circumferential direction;

[0041] The outer edge of the elastic membrane is bonded to the inner edge of the waterproof breathable membrane through a first annular adhesive layer, the inner diameter of the limiting ring is not less than the inner diameter of the first adhesive layer, and the ratio of the width of the limiting ring to the width of the first adhesive layer is not less than 0.3.

[0042] The limiting ring is located on the surface of the elastic membrane facing the valve cover, and its inner diameter is not less than the inner diameter of the first rubber layer, and its width is not less than 0.3 of the width of the first rubber layer. When the elastic membrane expands and bulges upward toward the valve cover, it will contact the end of the limiting ring facing the support plate. Since the limiting ring and the outer circle part of the first rubber layer overlap with a certain width, the elastic membrane and the first rubber layer can be prevented from being separated from the bonding area after the elastic membrane expands and bulges upward, and the inner edge of the limiting ring is prevented from hindering the upward expansion and bulging of the elastic membrane, ensuring that the elastic membrane can bulge upward smoothly under the action of the internal and external pressure difference, so that it can burst normally and quickly under the bursting pressure.

[0043] Furthermore, the width of the limiting ring at the starting end close to the support plate is greater than the width of the limiting ring at the end close to the valve cover, and the outer diameter thereof is not greater than 1.1 times the outer diameter of the elastic membrane.

[0044] Such arrangement can also avoid as much as possible the inner wall of the restriction ring from hindering the upward expansion and bulging of the elastic membrane, and ensure that the elastic membrane can expand, bulge and burst smoothly under the action of the internal and external pressure difference.

[0045] Alternatively, the width of the first adhesive layer is 5-10% of the diameter of the elastic membrane, so as to ensure that the elastic membrane is firmly bonded, ensure the waterproof performance of the membrane assembly as a whole under normal use conditions, and avoid the outer edge of the elastic membrane from being separated from the first adhesive layer when the internal and external pressure difference does not reach the bursting pressure; and the elastic membrane will not be restricted from expanding or bulging due to the excessively wide bonding area.

[0046] Alternatively, an isolation ring is provided between the outer edge of the elastic membrane and the restriction ring, and the width of the isolation ring is not less than the width of the restriction ring.

[0047] The isolation ring separates the outer edge of the elastic membrane from the restriction ring to prevent the outer edge of the elastic membrane from directly contacting the restriction ring, and also plays a role in protecting the elastic membrane.

[0048] Furthermore, a piercing member is provided on the end surface of the valve cover facing the support plate, and a gap is provided between the piercing member and the elastic membrane.

[0049] A gap is set between the puncture piece and the elastic membrane. When the pressure difference between the inside and outside of the elastic membrane reaches the bursting pressure, it expands and bulges upward to a bursting height. The elastic membrane that has expanded and stretched greatly contacts the puncture piece, forming a large breach instantly. The gas bound inside the membrane assembly quickly sprays outward to achieve pressure relief.

[0050] Alternatively, at least one side of the elastic membrane is provided with a notch, and the thickness of the notch is very thin, and when the internal and external pressure difference reaches the bursting pressure, the notch quickly breaks and forms a large crack. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 A cross-sectional view of an explosion-proof valve provided in an embodiment of the present application;

[0052] Figure 2 and Figure 3 They are Figure 1 The three-dimensional and cross-sectional views of the middle valve seat;

[0053] Figure 4 for Figure 1 A top view of the middle valve body;

[0054] Figure 5 for Figure 1 Schematic diagram of the first structure of the middle membrane assembly, the restriction ring and the support net;

[0055] Figure 6 for Figure 1 Schematic diagram of the second structure of the middle membrane assembly, the restriction ring and the support net;

[0056] Wherein: 100-explosion-proof valve, 1-valve body, 10-valve seat, 11-valve head, 12-cylinder, 13-support plate, 130-air hole, 131-first air hole, 132-second air hole, 133-first zone, 134-second zone, 135-annular zone, 136-connecting block, 2-valve cover, 3-membrane assembly, 31-elastic membrane, 32-waterproof breathable membrane, 4-support net, 5-limiting ring, 50-connecting rib, 6-puncture piece, 71-first rubber layer, 72-second rubber layer, 73-third rubber layer, 74-fourth rubber layer, 75-fifth rubber layer, 8-isolating ring. DETAILED DESCRIPTION

[0057] like Figure 1-3The disclosed explosion-proof valve 100 includes a valve body 1 and a valve cover 2 connected to one end thereof. The valve body 1 includes a valve seat 10 and a valve head 11 connected as one body. The valve seat 10 includes a hollow cylinder 12 with an external thread on the outer wall and a support plate 13 formed integrally at the top of the cylinder 12. The support plate 13 has an air vent 130. Among them, the explosion-proof valve 100 is sealed and installed to the battery pack through the external thread and the sealing ring on the outer wall of the cylinder 12. The valve head 11 is also a hollow structure, one end of which is connected to the outer ring of the support plate 13 of the valve seat 10, and then connected to the valve seat 10 to form an integrated valve body 1. For example, the valve head 11 can be formed on the outer ring of the support plate 13 in the form of secondary rubber encapsulation, and then the support plate 13 is wrapped inside the valve body 1. The valve cover 2 is fixed to the top of the valve head 11 by snap connection, welding or bonding.

[0058] In addition, a membrane assembly 3 is provided on the end surface of the support plate 13 facing the valve cover 2, wherein the membrane assembly 3 includes a waterproof elastic membrane 31 and a waterproof breathable membrane 32, covering the air hole 130; the elastic membrane 31 is located in the central area of ​​the support plate 13, and the waterproof breathable membrane 32 is surrounded on the outside of the elastic membrane 31.

[0059] Under normal working conditions, the temperature of the battery pack does not rise or fall very fast, and a high internal and external pressure difference will not be formed. In addition, the battery pack has a certain strength and will not be damaged by a small increase in air pressure in a short period of time. Therefore, the requirements for the air permeability of the explosion-proof valve in daily use are not very high, and ordinary PTFE membranes can meet its normal air permeability requirements. However, once the battery pack becomes abnormal, the temperature inside it will rise significantly in a short period of time, and the internal and external pressure difference will also increase rapidly. At this time, higher requirements are placed on the air permeability of the explosion-proof valve, which needs to respond quickly and release pressure quickly after reaching the bursting pressure.

[0060] In the explosion-proof valve 100 provided in the present application, the membrane assembly 3 covering and sealing the vent hole 130 includes a waterproof elastic membrane 31 and a waterproof breathable membrane 32. When installed on a device such as a battery pack, the waterproof and breathable requirements of the battery pack under normal operating conditions can be ensured. Under normal use conditions of the battery pack, the waterproof and breathable membrane 32 plays a role in balancing the internal and external pressures, preventing the elastic membrane 31 from excessively bulging and expanding upwards under the internal and external pressure difference that is much smaller than the bursting pressure, thereby preventing the elastic membrane 31 from being in an excessively expanded and stretched state for a long time, and protecting the elastic membrane 31; of course, a certain amount of gas may be generated in a short period of time during normal charging and discharging of the battery pack. Since it takes time for the waterproof and breathable membrane 32 to discharge the gas, the elastic membrane 31 may bulge upwards for a short period of time, but it will not damage the elastic membrane 31. In addition, since the elastic membrane 31 is also waterproof, it forms a membrane assembly 3 combination with the waterproof and breathable membrane 32, which together play a waterproof function to prevent liquid water from entering the interior of the explosion-proof valve 100 and protect the battery pack. The overall waterproof level of the membrane assembly 3 can reach IPX7, which can meet the waterproof and breathable requirements under normal working conditions.

[0061] Furthermore, by arranging the elastic membrane 31 in the central area of ​​the support plate 13 and the waterproof and breathable membrane 32 around the outer side of the elastic membrane 31, the elastic membrane 31 and the waterproof and breathable membrane 32 are arranged in this way, so that the space inside the explosion-proof valve 100 is more fully utilized, and the explosion-proof valve 100 has a more compact structure; more importantly, the elastic membrane 31 is located in the center and is horizontally spaced a certain distance from the inner wall of the valve body 1, that is, the inner wall of the valve head 11, so as to prevent the elastic membrane 31 from bulging upwards and abutting against the valve head 11 under the action of the internal and external pressure difference. The elastic membrane 31 cannot rupture normally when the internal and external pressure difference reaches the bursting pressure, and a battery pack explosion accident occurs. Moreover, separating the elastic membrane 31 from the inner wall of the valve head 11 can also prevent it from rupturing prematurely due to abutting against or hitting the inner wall of the valve head 11 after expansion and bulging, thereby ensuring that the elastic membrane 31 can remain intact and the membrane assembly 3 can work normally under the internal and external pressure difference lower than the bursting pressure, providing reliable waterproof and breathable performance.

[0062] When an abnormality occurs in the battery pack, the pressure difference between the inside and outside of the membrane assembly 3 increases in a very short time and reaches the bursting pressure.

[0063] The expansion and bulging of the elastic membrane 31 can be roughly divided into two stages:

[0064] In the first stage, at this time, the internal and external pressure difference of the membrane assembly 3 is still relatively small, and there is still a certain gap with the bursting pressure, but the internal and external pressure difference is increasing rapidly, and the elastic membrane 31 expands and bulges upward toward the valve cover 2 under the action of the internal and external pressure difference, and the elastic membrane 31 is stretched, and the thickness decreases and becomes thinner. When the internal and external pressure difference approaches the bursting pressure of the explosion-proof valve 100, the elastic membrane 31 has expanded greatly, similar to a bulging balloon, but in this stage, the elastic membrane 31 is still within its tolerance range and will not rupture;

[0065] In the second stage, the internal and external pressure difference continues to increase from a value close to the bursting pressure, and in this stage, the elastic membrane 31 expands and bulges upward at a greater increment relative to the unit internal and external pressure difference increment. Therefore, when the internal and external pressure difference reaches the bursting pressure, the bulging height of the elastic membrane 31 reaches the bursting height. The elastic membrane 31, which has been stretched very thin and stretched very tight, will burst at the moment when the pressure difference reaches the bursting pressure, forming a large breach, and the gas in the valve will quickly spray outward from the breach. After the elastic membrane 31 forms a breach, the gas spraying outward at a very fast speed forms an airflow that will impact the elastic membrane 31, and the middle area has the greatest impact force of the airflow, causing the breach to be further torn, thereby achieving rapid pressure relief.

[0066] On the one hand, the membrane assembly 3 composed of a waterproof elastic membrane 31 and a waterproof breathable membrane 32 is applied to the explosion-proof valve 100, which enables the explosion-proof valve 100 to have both good waterproofness and rapid pressure relief function, which meets the application scenario requirements of the explosion-proof valve 100 and solves the technical problems that have always existed in the field of explosion-proof valve technology but are difficult to solve.

[0067] On the other hand, since the conventional practice has always been to apply a single PTFE membrane to the explosion-proof valve 100 and to set a puncture piece on the inner surface of the valve cover 2, the present application proposes to combine a waterproof elastic membrane 31 and a waterproof breathable membrane 32 together, and the elastic membrane 31 is located in the central area of ​​the support plate 13, and the waterproof breathable membrane 32 is surrounded by the outside of the elastic membrane 31, forming a combination of a membrane component 3 with the elastic membrane 31 in the center and the waterproof breathable membrane 32 on the periphery, and the combination of the membrane component 3 is applied to the explosion-proof valve 100. At the moment when the internal and external pressure difference of the combination of the membrane component 3 reaches the bursting pressure, the elastic membrane 31 can quickly burst to achieve good waterproofness and rapid pressure relief function. The proposal of the combination of the membrane component 3 itself is groundbreaking, and provides a new solution for taking into account the good waterproofness and rapid pressure relief function of the explosion-proof valve 100.

[0068] As mentioned above, under different internal and external pressure difference ranges, the elastic membrane 31 expands and bulges upward at different increments per unit internal and external pressure difference increment, so that under the action of a lower internal and external pressure difference, the height of the elastic membrane 31 that bulges upward can be controlled to avoid the elastic membrane 31 being in a state of large-scale stretching for a long time, thereby protecting the elastic membrane 31 and preventing it from rupturing prematurely. When the internal and external pressure difference is close to the bursting pressure, the elastic membrane 31 expands and bulges upward at a greater increment per unit internal and external pressure difference increment, thereby ensuring that the elastic membrane 31 can quickly burst and release pressure under the bursting pressure.

[0069] The waterproof breathable membrane 32 may be a single PTFE membrane, or the waterproof breathable membrane 32 may be a composite of an upper PTFE breathable membrane and a lower non-woven fabric support layer.

[0070] In some embodiments, at least one side of the elastic membrane 31 is provided with a notch, for example, the ratio of the depth of the notch to the thickness of the elastic membrane 31 is 0.1 to 0.5, that is, the thickness of the membrane corresponding to the notch is smaller, which is conducive to the elastic membrane 31 to explode quickly under the blasting pressure to form a relatively large rupture.

[0071] Or, in another embodiment, Figure 1 As shown, the end surface of the valve cover 2 facing the support plate 13 is further provided with a piercing member 6, wherein the piercing member 6 and the elastic membrane 31 are spaced apart, that is, the end of the piercing member 6 is spaced apart from the elastic membrane 31, and the distance between the two is defined as the bursting height H of the explosion-proof valve 100. When the internal and external pressure difference reaches the bursting pressure of the elastic membrane 31, the height of its upward bulging also reaches the bursting height, and the elastic membrane 31, which has been stretched very thin and very tight, bursts at the moment of contacting the sharp part of the end of the piercing member 6, forming a large breach.

[0072] In order to better realize the ventilation of the vent hole 130 under normal working conditions and the rapid ejection of gas under bursting pressure, the structure of the vent hole 130 is also optimized. Figure 2-3As shown, the air hole 130 includes a first air hole 131 and a second air hole 132 which are arranged at intervals. The first air hole 131 is located in the central area of ​​the support plate 13, and the second air hole 132 is surrounded on the outside of the first air hole 131. The first air hole 131 and the second air hole 132 each include a plurality of holes. Accordingly, the elastic membrane 31 covers all the first air holes 131, and the waterproof breathable membrane 132 covers all the second air holes 132. The first air hole 131 located in the center corresponds to the elastic membrane 31, and the second air hole 132 located on the outside corresponds to the waterproof breathable membrane 32. Under normal working conditions, the second air hole 132 passes the gas inside the membrane assembly 3 to the waterproof breathable membrane 32 to balance the internal and external pressures. When the waterproof breathable membrane 32 cannot discharge the gas inside the membrane assembly 3 in time, the pressure inside the membrane assembly 3 increases, forming an internal and external pressure difference, and the internal gas pushes up the elastic membrane 31 through the first air hole 131, and the elastic membrane 31 bulges upward and increases in volume. When the internal and external pressure difference reaches the bursting pressure, the height of the elastic membrane 31 bulging upward reaches the bursting height, and it explodes instantly and releases pressure quickly.

[0073] The support plate 13 includes a first area 133 in which a plurality of first air holes 131 are arranged and a second area 134 for fixing the outer edge of the waterproof breathable membrane 32; the first area 133 has an annular area 135 located on the outer circle, which is used to fix the outer edge of the elastic membrane 31 and the inner edge of the waterproof breathable membrane 32, and the outer wall of the annular area 135 is connected to the inner wall of the second area 134 through a plurality of connecting blocks 136 arranged at intervals in the circumferential direction, and the adjacent connecting blocks 136 and the outer wall of the annular area 135 and the inner wall of the second area 134 are arranged to form the second air holes 132.

[0074] The annular area 135 and the second area 134 of the outer ring of the first area 133 of the support plate 13 respectively fix and support the inner edge and the outer edge of the waterproof breathable membrane 32, and the annular area 135 of the outer ring of the first area 133 fixes and supports the outer edge of the elastic membrane 31, so that the waterproof breathable membrane 32 and the elastic membrane 31 can perform their respective functions, thereby ensuring that the membrane assembly 3 can have both good waterproof performance and rapid pressure relief function.

[0075] Of course, the second air hole 132 can also be an integrated annular hole structure surrounding the outside of the first air hole 131. In this way, without the obstruction of the connecting block 136, the air permeability of the waterproof breathable membrane 31 is greater under normal working conditions. The first air hole 131 can also be an integrated circular hole structure. In this way, the gas in the valve can be ejected out quickly and unhindered at the moment when the elastic membrane 31 explodes.

[0076] The area of ​​the first air hole 131 is larger than that of the second air hole 132. After the elastic membrane 31 explodes, the airflow impact is greater, and it is easier to tear a large crack, resulting in a better pressure relief effect.

[0077] In a more preferred embodiment, Figure 5-6 As shown, a support net 4 is also provided between the membrane assembly 3 and the air hole 130, and the support net 4 at least separates the elastic membrane 31 from the support plate 13. When the external pressure of the membrane assembly 3 is higher than the internal pressure, the elastic membrane 31 is sunken into the air hole 130, that is, sunken into the first air hole 131, which may damage the elastic membrane 31, resulting in a deterioration of the waterproof performance of the elastic membrane 31; or, when the elastic membrane 31 is impacted by liquid water, it will also be sunken into the first air hole 131, thereby causing wear; the support net 4 is used to separate the elastic membrane 31 from the support plate 13, that is, to separate the elastic membrane 31 from the first air hole 131, so that no matter it is impacted by external pressure or liquid water, under the support and holding action of the support net 4, the depression of the elastic membrane 31 is limited, and it is basically kept flat, avoiding wear and tear, and can be kept intact, ensuring the overall waterproof performance of the elastic membrane 31, so that the membrane assembly 3 can provide its due waterproof effect.

[0078] like Figure 1 and Figure 4 As shown, a limiting ring 5 is also provided on the side of the elastic membrane 31 facing the valve cover 2, and its outer wall is connected to the inner wall of the valve body 1, i.e., the valve head 11, through a plurality of connecting ribs 50 arranged at intervals in the circumferential direction; moreover, the width of the limiting ring 5 at the starting end close to the support plate 13 is greater than its width toward the end close to the valve cover 2, and the limiting ring 5 is a narrow-upper-wide-lower structure, for example, its vertical cross-section is roughly a trapezoidal shape with a narrow-upper-wide-lower cross-section. Such a configuration is also to avoid as much as possible that the inner wall of the limiting ring 5 hinders the upward expansion and bulging of the elastic membrane 31, and ensure that the elastic membrane 31 can expand, bulge and burst smoothly under the action of the internal and external pressure difference. Better, for example, the outer diameter of the limiting ring 5 is not greater than 1.1 times the outer diameter of the elastic membrane 31, to avoid excessive shielding of the waterproof and breathable membrane 32.

[0079] like Figure 4-5 As shown, the outer edge of the elastic membrane 31 and the inner edge of the waterproof breathable membrane 32 are bonded by the annular first adhesive layer 71, the inner diameter D of the limiting ring 5 is not less than the inner diameter D1 of the first adhesive layer 71, and the ratio of the width W of the limiting ring 5 to the width W1 of the first adhesive layer 71 is not less than 0.3. For example, W / W1=0.3, 0.4, etc. The limiting ring 5 is arranged on the side of the elastic membrane 31 facing the valve cover 2, and the two can be in contact or not. When the elastic membrane 31 expands and bulges upward toward the valve cover 2, it will contact the end of the limiting ring 5 facing the support plate 13. Since the outer ring part of the limiting ring 5 and the first adhesive layer 71 overlaps with a certain width, the area where the elastic membrane 31 and the first adhesive layer 71 are bonded can be prevented from being separated, and at the same time, the inner edge of the limiting ring 5 is prevented from hindering the upward expansion and bulging of the elastic membrane 31, ensuring that the elastic membrane 31 can bulge upward smoothly under the action of the internal and external pressure difference, so that it can be normally and quickly exploded under the bursting pressure.

[0080] The width W1 of the first adhesive layer 71 is 5-10% of the diameter D2 of the elastic membrane 31, which ensures that the elastic membrane 31 is firmly bonded, ensures the waterproof performance of the membrane assembly 3 as a whole under normal use conditions, and avoids the outer edge of the elastic membrane 31 from being separated from the first adhesive layer 71 when the internal and external pressure difference does not reach the bursting pressure; moreover, the expansion and bulging of the elastic membrane 31 will not be restricted due to the excessive width of the bonding area.

[0081] In order to more conveniently fix the membrane assembly 3 to the support plate 13 and better protect the elastic membrane 31 , the following assembly structure is adopted for the membrane assembly 3 .

[0082] like Figure 5 As shown, the outer edge of the elastic membrane 31 and the inner edge of the waterproof breathable membrane 32 are bonded by the annular first adhesive layer 71 to form a membrane assembly 3, that is, the outer edge of the elastic membrane 31 and the inner edge of the waterproof breathable membrane 32 are bonded together by the first adhesive layer 71 to form an integrated membrane assembly 3; and the outer edge of the end surface of the waterproof breathable membrane 32 facing the support plate 13 is bonded to the outer edge of the support net 4 by the second adhesive layer 72, thereby connecting the membrane assembly 3 and the support net 4 into a whole, and the third adhesive layer 73 is pasted on the outer edge of the end surface of the support net 4 facing the support plate 13, and the whole formed by the membrane assembly 3 and the support net 4 is fixed to the end surface of the support plate 13 facing the valve cover 2 by the third adhesive layer 73. Of course, the elastic membrane 31 and the waterproof breathable membrane 32 can also be bonded to the end surface of the support plate 13 facing the valve cover 2.

[0083] An isolation ring 8 is provided between the outer edge of the elastic membrane 31 and the limiting ring 5, and is bonded to the surface of the elastic membrane 31 facing the valve cover 2, and the width W2 of the isolation ring 8 is not less than the width W of the limiting ring 5. The isolation ring 8 separates the outer edge of the elastic membrane 31 from the limiting ring 5 to prevent the outer edge of the elastic membrane 31 from directly contacting the limiting ring 5, and also plays a role in protecting the elastic membrane 31. Alternatively, the isolation ring 8 can also be bonded to the end surface of the limiting ring 5 facing the support plate 13.

[0084] The isolating ring 8 is bonded to the outer edge of the end surface of the elastic membrane 31 facing the valve cover 2 through the fourth adhesive layer 74, that is, after the membrane assembly 3 and the support net 4 are bonded to form a whole, they are bonded to the isolating ring 8 through the fourth adhesive layer 74, and finally all the components formed into one are fixed to the end surface of the second area 134 of the support plate 13 facing the valve cover 2 through the third adhesive layer 73, and then the valve head 11 is formed on the outer ring of the support plate 14 in the form of rubber coating, and then the membrane assembly 3, the support net 4 and the isolating ring 8 are wrapped inside the valve body 1. In addition, the limiting ring 5 is also synchronously formed on the side of the isolating ring 8 facing the valve cover 2 during the process of forming the valve head 11 by rubber coating.

[0085] It should be noted that, in this embodiment, the outer diameter of the support net 4 is equal to the outer diameter of the waterproof breathable membrane 32 , that is, the outer edges of the two are flush, so that the support net 4 simultaneously separates the elastic membrane 31 and the waterproof breathable membrane 32 from the support plate 13 .

[0086] Of course, in other embodiments, such as Figure 6 As shown, the outer diameter of the support net 4 is equal to the outer diameter of the elastic membrane 31, and accordingly, the support net 4 only serves to separate the elastic membrane 31 from the support plate 13. The outer edge of the end surface of the support net 4 facing the valve cover 2 is still bonded to the inner edge of the waterproof breathable membrane 32 through the second adhesive layer 72, and the outer edge of the end surface of the support net 4 facing the support plate 13 is bonded to the annular area 135 of the outer circle of the first area 133 through the third adhesive layer 73, while the outer edge of the waterproof breathable membrane 32 is bonded to the second area 134 of the support plate 13 through the fifth adhesive layer 75.

[0087] To ensure strong bonding and avoid blocking the breathable area of ​​the waterproof breathable membrane 132 , the width of the second adhesive layer 72 and the width of the third adhesive layer 73 are both 4-8% of the outer diameter of the support mesh 4 , and the outer edges of the second adhesive layer 72 and the third adhesive layer 73 are flush with the outer edges of the support mesh 4 .

[0088] To ensure that the isolation ring 8 effectively isolates the restriction ring 5, the width of the isolation ring 8 and the width of the fourth adhesive layer 74 are both selected to be 5-10% of the outer diameter of the elastic membrane 31. The width of the isolation ring 8 is not less than the width of the restriction ring 5, and the inner diameter is not greater than the inner diameter of the restriction ring 5.

[0089] In the present application, the bursting pressure of the explosion-proof valve 100 is designed to be 5-15kPa. Of course, based on the structure of the present application, the bursting pressure can be adjusted according to actual needs. Among them, the test method of the bursting pressure of the explosion-proof valve is: preset the gas source pressure, then connect the explosion-proof valve to the gas source, and observe whether the elastic membrane bursts; if the explosion does not occur under a certain preset gas source pressure, disconnect the explosion-proof valve, and increase the preset pressure of the gas source with a gradient of 0.1kpa, repeat the above operation until the explosion-proof valve bursts under a certain preset gas source pressure, and record the preset gas source pressure at this time, which is the bursting pressure of the explosion-proof valve.

[0090] Example 1

[0091] A PDMS elastic membrane sample 1 with a thickness of 100 μm is selected, and the diameter of the effective area of ​​the elastic membrane 31 is 25 mm, and a ring-shaped waterproof breathable membrane 32 with a certain inner and outer diameter is used. The waterproof breathable membrane 32 is set to meet daily ventilation needs. Specifically, in this embodiment, the inner diameter of the effective working area of ​​the waterproof breathable membrane 32 is 30 mm and the outer diameter is 36 mm. The elastic membrane 31 and the waterproof breathable membrane 32 are both fixed by bonding. The distance between the elastic membrane and the puncture piece is 30 mm, and its waterproof performance reaches IPX7. The measured burst pressure is 7 kPa, and the air permeability after the burst is 71 L / min@0.5 kpa, and the explosion-proof valve 100 can pass the vibration test.

[0092] Among them, the test process of the air permeability data of the explosion-proof valve after the explosion: the explosion-proof valve 100 after the elastic membrane 31 explodes is used as a test sample, and the air source pressure is preset to 0.5kpa, and then the explosion-proof valve 100 is connected to the air source, and the amount of gas passing through the explosion-proof valve 100 within a certain period of time is measured, and the air permeability of the explosion-proof valve 100 after the elastic membrane 31 explodes is calculated accordingly.

[0093] Comparative Example 1

[0094] 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 composite explosion-proof membrane assembly 3, the composite explosion-proof membrane assembly 3 in Example 1 is replaced with a single PTFE membrane, and the diameter of the PTFE breathable membrane is the same as the outer diameter of the waterproof breathable membrane 32 in Example 1, and the membrane selection is also the same. In order to ensure that the explosion-proof valve can be successfully exploded, the knife-membrane spacing of the explosion-proof valve is set to 1mm. The explosion pressure of the explosion-proof valve in this comparative example is tested to be about 7kpa. Its waterproof grade is IPX7, but after the single PTFE membrane explodes, the air permeability of the explosion-proof valve is about 16L / min@0.5kpa, and the explosion-proof valve of this comparative example can pass the vibration test. Obviously, although the single PTFE membrane explosion-proof valve in this comparative example has a similar bursting pressure to Example 1 and also has good waterproof performance, its pressure relief capacity after explosion is significantly weaker.

[0095] Comparative Example 2

[0096] On the basis of Comparative Example 1, in order to ensure the good pressure relief capacity of the explosion-proof valve after the explosion, this comparative example replaces the PTFE membrane in Comparative Example 1 with a PTFE membrane with higher porosity. Specifically, the air permeability per unit area of ​​the PTFE membrane in this comparative example is 2.2 times that of the PTFE membrane in Comparative Example 1, and the knife-film spacing of the explosion-proof valve is set to 1.2mm. On the one hand, the explosion-proof valve in this comparative example is difficult to pass the vibration test, and on the other hand, it cannot pass the IPX7 test, and has a relatively obvious water leakage phenomenon at a water depth of 1m, so it cannot meet the use requirements. Although increasing the porosity of the PTFE membrane can indeed make the explosion-proof valve have a relatively higher air permeability after the explosion, it cannot pass the vibration test, does not have sufficient water resistance, and has no practical application value.

[0097] Comparative Example 3

[0098] On the basis of comparative example 1, in order to ensure good pressure relief capability after the explosion-proof valve bursts, this comparative example replaces the PTFE membrane in comparative example 1 with a PTFE membrane with higher porosity. Specifically, the air permeability per unit area of ​​the PTFE membrane in this comparative example is about 1.5 times that of the PTFE membrane in comparative example 1, and in order to prevent it from being damaged during the vibration test, the knife-film spacing of the explosion-proof valve is set to 1.5mm. Although the explosion-proof valve in this comparative example can pass the IPX7 test and the vibration test, its burst pressure is slightly larger, which is 10.2kpa, and the air permeability after the burst is 21L / min@0.5kpa. The explosion-proof valve in this comparative example does have better post-explosion pressure relief performance than comparative example 1 by using a PTFE membrane with greater porosity, but it is still far lower than that of Example 1; in addition, it is not difficult to conclude from the test results of comparative example 2 that the porosity of the PTFE membrane is not suitable for further improvement, so as to avoid insufficient waterproof performance of the explosion-proof valve, and on the basis of the high porosity of the PTFE membrane, the distance between the PTFE membrane and the puncture piece is not suitable for further reduction, so as to avoid failure to pass the vibration test. Obviously, whether by adjusting the porosity of the PTFE membrane or by adjusting the distance between the knife and the membrane, it is difficult to achieve both explosion pressure relief performance and waterproof performance on the basis of meeting the vibration performance requirements.

[0099] The above test results show that the explosion-proof valve 100 provided in Example 1 of the present application uses a membrane assembly 3 composed of an elastic membrane 31 and a waterproof breathable membrane 32, and the elastic membrane 31 is located in the central area, and the waterproof breathable membrane 32 is arranged around the outside of the elastic membrane 31. Since the elastic membrane 31 can form a large breach after the explosion, the air permeability after the explosion is at least several times that of the ordinary PTFE membrane after the explosion, and the gas in the valve can be quickly ejected outward to achieve rapid pressure relief. Moreover, under normal use conditions of the battery pack, the waterproof level reaches IPX7, and the gas is discharged through the breathable membrane 31 to balance the internal and external pressure differences, so it has both good waterproof and explosion pressure relief performance.

[0100] 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.

[0101] Example 2

[0102] The difference between this embodiment and embodiment 1 is that, on the one hand, a PDMS elastic film sample 2 with a thickness of 60 μm is selected, and on the other hand, the distance between the elastic film and the puncture piece is controlled to be 20 mm. Its waterproof performance reaches IPX7. Tests have found that it explodes earlier. When the internal and external pressure difference is 5 kPa, the elastic film explodes, that is, the explosion pressure is 5 kPa, and the air permeability after the explosion is 84 L / min@0.5 kpa.

[0103] Example 3

[0104] The difference between this embodiment and embodiment 1 is that a PDMS elastic film sample 3 with a thickness of 150 μm is selected, and the diameter of the effective area of ​​the elastic film is 25 mm, and the distance between the elastic film and the puncture piece is controlled to be 40 mm. Its waterproof performance reaches IPX7. Tests have found that it is more difficult to explode. The elastic film will not explode until the internal and external pressure difference reaches 10 kpPa, that is, the explosion pressure reaches 10 kPa, and the air permeability after the explosion is 62 L / min@0.5 kpa.

[0105] Example 4

[0106] The difference between this embodiment and embodiment 1 is that a PDMS elastic film sample 4 with a thickness of 200 μm is selected, and the diameter of the effective area of ​​the elastic film is 25 mm, and the distance between the elastic film and the piercing member is controlled to be 50 mm, and its waterproof performance reaches IPX7. The test found that it is more difficult to burst, and the elastic film will not burst until the internal and external pressure difference reaches 15 kpPa, that is, the bursting pressure reaches 15 kPa, and the air permeability after the burst is 44 L / min@0.5 kpa. Although the explosion-proof valve in this embodiment has a lower air permeability after the burst than that of embodiments 1-3, it is still significantly higher than the air permeability after the burst of the single PTFE film explosion-proof valve in comparative examples 1-3.

[0107] For K1 and K2 of each embodiment, an explosion-proof valve with a bursting pressure of 7kPa is used as an example to explain and illustrate that when the internal and external pressure difference of the membrane assembly 3 reaches close to 7kPa (greater than 85% of the bursting pressure), the membrane assembly 3 of the explosion-proof valve 100, i.e., the elastic membrane 31, is required to be able to quickly burst and release pressure, otherwise the battery pack is likely to explode. However, it is not desirable that the elastic membrane 31 bursts under a relatively low internal and external pressure difference (not greater than 85% of the bursting pressure, 6kpa), because under an internal and external pressure difference of 6kPa, the battery pack can continue to work normally and will not explode, that is, it is desired that when the internal and external pressure difference is 6kPa, although the elastic membrane 31 expands and bulges, it is still within its tolerance range and will not burst. When the internal and external pressure difference is lower than 7 kPa, the bulging height of the elastic membrane 31 needs to reach a certain value to ensure that it will not burst prematurely, and to ensure that when the internal and external pressure difference further increases, the elastic membrane 31 continues to bulge upward on the basis of the bulging height, so as to ensure that when the bursting pressure is reached, it can respond quickly and release pressure quickly.

[0108] The bulging height of the samples of the above four elastic membranes 31 is tested under different internal and external pressure differences, and the diameter of the effective area is controlled to be 25 mm. Specifically, an explosion-proof valve can be made for testing, or the elastic membrane 31 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 0.5 kPa / s until it reaches the explosion-proof valve, ensuring that the elastic membrane 31 has sufficient deformation time until the pressure difference on both sides reaches 85% of the bursting pressure of the explosion-proof valve and reaches 100% of the bursting pressure. The corresponding bulging height of the elastic membrane 31 is recorded in real time, and the increment K value of the bulging height of the elastic membrane 31 under the corresponding unit internal and external pressure difference increment is calculated, as shown in Table 1 below.

[0109] Table 1 Corresponding to the increment K value of the bulging height of the elastic membrane under the unit internal and external pressure difference increment

[0110]

[0111] From the above data, it can be seen that the elastic membrane 31 has different increments of the upward bulging height K under different internal and external pressure difference ranges and unit internal and external pressure difference increments. And when K1 is less than K2 (such as in Examples 1-3), it can ensure that the explosion-proof valve 100 has a further preferred post-explosion air permeability after explosion compared with Example 4 (K1 and K2 are basically the same).

[0112] When the pressure difference between the inside and outside of the elastic membrane 31 is less than 85% of the bursting pressure of the explosion-proof valve 100, the increment of the height of the elastic membrane 31 bulging toward the valve cover 2 per unit increment of the pressure difference between the inside and outside of the elastic membrane 31 is K1. When the ratio of the pressure difference between the inside and outside of the elastic membrane 31 to the bursting pressure of the explosion-proof valve is between 85% and 100%, the increment of the height of the elastic membrane 31 bulging toward the valve cover 2 per unit increment of the pressure difference between the inside and outside of the elastic membrane 31 is K2, satisfying: 1.5≤K1≤4.5, and K2 / K1=1.1~5, wherein the axial height of the elastic membrane 31 bulging toward the valve cover 2 is in mm, and the unit of the pressure difference between the inside and outside of the elastic membrane 31 is in kPa.

[0113] In a smaller range of internal and external pressure differences, the K value is slightly smaller, that is, when the internal and external pressure difference is less than 85% of the bursting pressure, K1 takes a value between 1.5 and 4.5. Therefore, in a range of internal and external pressure differences that is far from the bursting pressure, the increment of the upward bulging height of the elastic membrane 31 per unit internal and external pressure difference increment is smaller, which can prevent the elastic membrane 31 from forming a large bulge prematurely and prevent the elastic membrane 31 from being in a large bulging state for a long time, that is, prevent the elastic membrane 31 from being in a large stretching state for a long time, reduce damage to the elastic membrane 31, ensure its integrity, and then extend the service life of the elastic membrane 31 to prevent it from bursting prematurely.

[0114] When the internal and external pressure difference is close to the bursting pressure, the K value is relatively large. When the ratio of the internal and external pressure difference to the bursting pressure of the explosion-proof valve 100 is between 85% and 100%, K2 is 1.1 to 5 times of K1. That is to say, in the internal and external pressure difference range close to the bursting pressure, as the internal and external pressure difference further increases, the elastic membrane 31 bulges upward with a greater increment per unit internal and external pressure difference increment, and the volume expands faster. When the internal and external pressure difference reaches the bursting pressure, the elastic membrane 31 explodes quickly to form a large rupture, and the gas bound therein is quickly ejected outward, thereby realizing the rapid pressure relief function.

[0115] As mentioned above, the internal and external pressure difference corresponding to the dividing point of the K value cannot be too far from the bursting pressure (85% of the bursting pressure in this application). Since the battery pack is in a vibrating working environment, if the internal and external pressure difference corresponding to the dividing point of the K value is too far from the bursting pressure, it is easy to appear under the internal and external pressure difference far below the bursting pressure, the bulge height is too high, and the elastic membrane 31 bursts early due to the vibration factor; at the same time, the internal and external pressure difference corresponding to the dividing point of the K value cannot be too close to the bursting pressure, otherwise, the internal and external pressure difference will reach the bursting pressure, but the bulge height of the elastic membrane 31 is not enough and cannot reach the bursting height, resulting in the elastic membrane 31 not being able to respond quickly under the bursting pressure and not being able to quickly release pressure. The above test results also prove this point. When the internal and external pressure difference corresponding to the dividing point of the K value is 85% of the bursting pressure, and K1 and K2 meet the above relationship, it can ensure the normal waterproof and breathable requirements of the explosion-proof valve 100 and the rapid bursting and pressure relief under the bursting pressure.

[0116] In addition, in Example 5, based on Example 4, the elastic membrane of PDMS material is replaced with a latex elastic membrane sample 5 of 170 μm thickness, and the spacing between the elastic membrane and the puncture piece is controlled to be 30 mm, and the rest is the same as Example 4. Its waterproof performance reaches IPX7. Tests show that it is more difficult to burst. The elastic membrane will not burst until the internal and external pressure difference reaches 12 kpPa, that is, the bursting pressure reaches 12 kPa, and the air permeability after the burst is 52 L / min@0.5 kpa. Further calculations show that the value of K2 / K1 is about 1.35, that is, for ordinary elastic membranes, if the internal and external pressure difference increases from 0 to the bursting pressure range, the difference in the K value of the upward bulging height increment of the elastic membrane 31 under the unit internal and external pressure difference is small, which can also meet the purpose of rapid bursting and instantaneous rapid exhaust of gas after bursting, but the air permeability after bursting is slightly smaller than that of samples 1-3. Of course, compared with Example 4 with roughly the same K2 and K1, this embodiment has a relatively more preferred air permeability after bursting.

[0117] Further analysis and summary of the test results of the bulging height data of the five samples of the elastic membrane 31 in the above-mentioned embodiments along with the pressure difference on both sides yield the following results:

[0118] For sample 1, the bursting height H is 20 mm, and the internal and external pressure difference is 70% of the bursting pressure, at this time h1 / H is 0.64.

[0119] For sample 2, the bursting height H is 15 mm, and the internal and external pressure difference is 70% of the bursting pressure, at this time h1 / H is 0.69.

[0120] For sample 3, the bursting height H is 30 mm, and the internal and external pressure difference is 70% of the bursting pressure, at this time h1 / H is 0.37.

[0121] For sample 4, the bursting height H is 30 mm, and the internal and external pressure difference is 70% of the bursting pressure, at this time h1 / H is 0.24.

[0122] For sample 5, the bursting height H is 30 mm, and the internal and external pressure difference is 70% of the bursting pressure, at this time h1 / H is 0.48.

[0123] Based on the above test results: when the pressure difference between the inside and outside of the elastic membrane 31 is 70% of the bursting pressure of the explosion-proof valve 100, the height h1 of the elastic membrane 31 bulging toward the valve cover 2 satisfies: h1 / H=0.2-0.7. Specific reasons explained:

[0124] When the internal and external pressure difference reaches 70% of the bursting pressure, the upward bulging height h1 of the elastic membrane 31 is not less than 20% of the bursting height H, so that when the internal and external pressure difference continues to increase and reaches the bursting pressure, the elastic membrane 31 continues to bulge upward, and the bulging height can reach the bursting height H. The volume of the elastic membrane 31 expands sufficiently and is in a stretched and taut state, and bursts at the moment the internal and external pressure difference reaches the bursting pressure, and the gas instantly sprays outward to quickly release the pressure. At the same time, it is limited that when the internal and external pressure difference reaches 70% of the bursting pressure, the upward bulging height h1 of the elastic membrane 31 is not greater than 70% of the bursting height H, so as to avoid the elastic membrane 31 forming a bulge that is too large and too close to the end of the piercing member 6 under the internal and external pressure difference far away from the bursting pressure. Since the battery pack is in a vibrating working environment, the elastic membrane 31 may burst prematurely due to the vibration if it bulges too early, that is, due to the vibration, the excessively bulged elastic membrane 31 is punctured prematurely by the piercing member 6 at a pressure lower than the bursting pressure.

[0125] Further analysis of the above test results revealed that:

[0126] For sample 1, the bursting height H is 20 mm, and the internal and external pressure difference is 85% of the bursting pressure, at which time h2 / H is 0.95.

[0127] For sample 2, the bursting height H is 15 mm, and the internal and external pressure difference is 85% of the bursting pressure, at this time h2 / H is 1.34.

[0128] For sample 3, the bursting height H is 30 mm, and the internal and external pressure difference is 85% of the bursting pressure, at this time h2 / H is 0.54.

[0129] For sample 4, the bursting height H is 30 mm, and when the internal and external pressure difference is 85% of the bursting pressure, h2 / H is 0.46.

[0130] For sample 5, the bursting height H is 30 mm, and the internal and external pressure difference is 85% of the bursting pressure, at which time h2 / H is 0.66.

[0131] Based on the above test results: when the internal and external pressure difference of the elastic membrane 31 is 85% of the bursting pressure of the explosion-proof valve 100, the height h2 of the elastic membrane 31 bulging toward the valve cover 2 satisfies h2 / H≥0.8, as in Example 1 and Example 2, which have a relatively better post-burst air permeability than Examples 3-5. Specific reasons are explained as follows:

[0132] When the pressure difference between the inside and outside of the elastic membrane 31 reaches 85% of the bursting pressure, the ratio of its bulging height h2 to the bursting height H is not less than 0.8, that is, when the pressure difference between the inside and outside is relatively close to the bursting pressure, the bulging height of the elastic membrane 31 is also relatively close to the bursting height, to ensure that when the pressure difference between the inside and outside continues to increase and reaches the bursting pressure, the bulging height h2 of the elastic membrane 31 reaches the bursting height H, and at the moment when the pressure difference between the inside and outside reaches the bursting pressure, it quickly blasts and bursts to achieve pressure relief.

[0133] In particular, the vertical distance between the end of the piercing member 6 and the end surface of the elastic membrane 31 facing the valve cover 2 is defined as the bursting height H of the explosion-proof valve 100. In the embodiment where the inner surface of the valve cover 2 is not provided with a piercing member, it can be recorded and measured by taking photos or videos, recording the position of the elastic membrane 31 at the moment of bursting and the highest point, measuring the vertical distance between the position and the end surface of the support plate 13 facing the valve cover 2, and the vertical distance minus the thickness of the elastic membrane 31 is the bursting height H. The values ​​of the bulging heights h1 and h2 of the elastic membrane 31 under the internal and external pressure difference less than the bursting pressure are obtained by real-time measuring the vertical distance between the highest point of the bulging elastic membrane 31 and the end surface of the support plate 13 facing the valve cover 2, and the vertical distance minus the thickness of the elastic membrane 31 is the bursting height H.

Claims

1. An explosion-proof valve, comprising a valve body and a valve cover connected to one end thereof, wherein a support plate is provided in the valve body, and the support plate has a vent hole; characterized in that: It also includes a membrane assembly disposed on the end surface of the support plate facing the valve cover, the membrane assembly includes a waterproof elastic membrane and a waterproof breathable membrane, covering the breathable hole; The elastic membrane is located in the central area of ​​the support plate, and the waterproof and breathable membrane is arranged around the outer side of the elastic membrane.

2. The explosion-proof valve according to claim 1, characterized in that: A support net is also provided between the membrane assembly and the air vents, and the support net at least separates the elastic membrane from the support plate.

3. The explosion-proof valve according to claim 1, characterized in that: When the pressure difference between the inside and outside of the elastic membrane is less than 85% of the bursting pressure of the explosion-proof valve, the increment of the height of the elastic membrane bulging toward the valve cover per unit increment of the pressure difference between the inside and outside is K1; when the ratio of the pressure difference between the inside and outside of the elastic membrane to the bursting pressure of the explosion-proof valve is between 85% and 100%, the increment of the height of the elastic membrane bulging toward the valve cover per unit increment of the pressure difference between the inside and outside is K2, satisfying: 1.5≤K1≤4.5, and K2 / K1=1.1~5, wherein the unit of the height of the elastic membrane bulging toward the valve cover is mm, and the unit of the pressure difference between the inside and outside of the elastic membrane is kPa.

4. The explosion-proof valve according to claim 1, characterized in that: The bursting height of the elastic membrane is H. When the pressure difference between the inside and outside of the elastic membrane is 70% of the bursting pressure of the explosion-proof valve, the height h1 of the elastic membrane bulging toward the valve cover satisfies: h1 / H=0.2-0.

7.

5. The explosion-proof valve according to claim 1, characterized in that: The bursting height of the elastic membrane is H. When the pressure difference between the inside and outside of the elastic membrane is 85% of the bursting pressure of the explosion-proof valve, the height h2 of the elastic membrane bulging toward the valve cover satisfies h2 / H≥0.

8.

6. The explosion-proof valve according to claim 1, characterized in that: The ventilation holes include a first ventilation hole and a second ventilation hole which are arranged at intervals, the first ventilation hole is located in the central area of ​​the support plate, the second ventilation hole is arranged around the outside of the first ventilation hole, the elastic membrane covers the first ventilation hole, and the waterproof breathable membrane covers the second ventilation hole.

7. The explosion-proof valve according to claim 6, characterized in that: The support plate includes a first area for setting the first air permeable hole and a second area for fixing the outer edge of the waterproof breathable membrane; The area of ​​the first air hole is larger than the area of ​​the second air hole; The first zone has an annular zone located in the outer circle, which is used to fix the outer edge of the elastic membrane and the inner edge of the waterproof breathable membrane. The outer wall of the annular zone is connected to the inner wall of the second zone through a plurality of connecting blocks arranged at circumferential intervals. The adjacent connecting blocks and the outer wall of the annular zone and the inner wall of the second zone are surrounded to form a second air hole.

8. The explosion-proof valve according to claim 1, characterized in that: It also includes a limiting ring located on the side of the elastic membrane facing the valve cover, the outer wall of which is connected to the inner wall of the valve body through a plurality of connecting ribs arranged at intervals in the circumferential direction; The outer edge of the elastic membrane is bonded to the inner edge of the waterproof breathable membrane through a first annular adhesive layer, the inner diameter of the limiting ring is not less than the inner diameter of the first adhesive layer, and the ratio of the width of the limiting ring to the width of the first adhesive layer is not less than 0.

3.

9. The explosion-proof valve according to claim 8, characterized in that: The width of the limiting ring at the starting end close to the support plate is greater than the width of the limiting ring at the end close to the valve cover, and the outer diameter thereof is not greater than 1.1 times the outer diameter of the elastic membrane; Alternatively, the width of the first adhesive layer is 5-10% of the diameter of the elastic film; Alternatively, an isolation ring is provided between the outer edge of the elastic membrane and the restriction ring, and the width of the isolation ring is not less than the width of the restriction ring.

10. The explosion-proof valve according to any one of claims 1 to 9, characterized in that: The end surface of the valve cover facing the support plate is also provided with a piercing member, and a gap is set between the piercing member and the elastic membrane; or, at least one side surface of the elastic membrane is provided with a notch.

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