A non-metallic seal leakage testing device and method under high pressure environment

Abstract

This invention discloses a leak testing device and method for non-metallic seals under high pressure, comprising a seal testing fixture, a pressure regulating system, and a temperature regulating system. The pressure regulating system includes a gas supply system and a pressurization system, which are sequentially connected via pipelines. The temperature regulating system includes a heat exchange medium connected to the seal testing fixture via pipelines. The seal testing fixture includes a base, an end plug, a gland, and a heat-conducting pipe. The base and gland cooperate to form a test chamber, with the end plug at least partially located within the test chamber. The seal to be tested is installed between the end plug and the base to form a seal. The end plug has an inner hole, and the heat-conducting pipe extends into the inner hole to form internal heat exchange. The heat-conducting pipe includes a heat exchange medium inlet and a heat exchange medium outlet. The testing device of this invention can meet the extreme service conditions of non-metallic seals under high-pressure hydrogen environments, and can perform tests such as temperature shock and pressure shock.

Description

Technical Field

[0001] This invention patent relates to the field of high-pressure hydrogen storage technology, specifically to a non-metallic sealing component leakage testing device and testing method used in high-pressure hydrogen storage. Background Technology

[0002] Hydrogen energy is diverse, clean, efficient, and regenerable, and has been elevated to a national energy strategic level by many countries. Currently, hydrogen storage methods mainly include high-pressure gaseous hydrogen storage, cryogenic liquid hydrogen storage, and solid-state hydrogen storage. High-pressure gaseous hydrogen storage has advantages such as simple container structure, fast hydrogen filling and discharging speed, low cost, and mature technology, making it one of the most widely used hydrogen storage methods at present. Hydrogen has a low density, low ignition energy, and a large combustion and explosion range (4%–74%), resulting in a high risk of explosion after leakage. Therefore, the sealing performance of high-pressure hydrogen storage systems is crucial for the safe use of hydrogen. Rubber O-rings are commonly used static sealing elements in high-pressure hydrogen systems, widely used in stationary high-pressure hydrogen storage tanks, vehicle-mounted high-pressure hydrogen cylinders, hydrogen dispensers, hydrogen dispensing nozzle separation devices, valves, and other high-pressure hydrogen systems. Rubber O-rings are highly elastic materials; when compressed under an interference fit, their elastic recovery forms contact stress with the sealing surface to achieve a sealing function. They are also low in cost, simple in structure, and easy to install and use, making them one of the key components for the safe and reliable operation of high-pressure hydrogen systems.

[0003] High-pressure hydrogen storage systems' static sealing structures may encounter extreme conditions during operation, such as pressures reaching 98 MPa and temperature variations ranging from -40 to 85°C. Furthermore, significant temperature and pressure fluctuations exist. Under these conditions, O-rings are prone to damage such as bubbling fracture, compression fracture, buckling fracture, and low-temperature glass transition, which can lead to leakage and seal failure in severe cases. Therefore, to ensure the sealing performance of O-rings in actual service scenarios and the safety of high-pressure hydrogen systems, it is necessary to design a detection device capable of simulating harsh service conditions (high pressure, pressure cycling, pressure shock, and high / low temperatures, temperature cycling, and temperature shock) to evaluate the sealing performance of O-rings under extreme conditions.

[0004] To study the performance of non-metallic seals under high-pressure hydrogen conditions, the inventors' team first proposed an experimental device (related patent ZL202210000275.X) and a testing method (related patent ZL202210000259.0) for testing the performance of non-metallic seals under high-pressure hydrogen conditions. These two inventions, by modifying the internal structure of the test chamber, conduct various types of tests on rubber seals under high-pressure hydrogen conditions and propose corresponding testing methods, such as static load exposure tests, cyclic pressure tests, and compression set tests. They study the performance of rubber seals under different temperatures and pressures, providing a reference for the rapid screening of the suitability of non-metallic seals under high-temperature and high-pressure hydrogen conditions. However, this system uses a method of placing the test chamber inside a high-low temperature environment chamber, and connects the refrigeration and heating system to the high-low temperature environment chamber through pipelines to form a refrigerant and heat transfer medium circulation loop, providing a suitable ambient temperature for the test chamber. Furthermore, Chinese patent CN112304531A controls hydrogen temperature changes and measures hydrogen leakage by controlling the temperature of the intake pipe and the external temperature of the water tank; Chinese patent CN 109406067A measures the sealing contact stress and leakage of O-rings under high-pressure hydrogen conditions, but does not mention the influence of temperature or the means of controlling the device temperature. None of the above-mentioned testing systems can perform temperature shock tests, nor can they conduct in-situ hydrogen leakage detection tests based on the combined effects of temperature shock, pressure, and hydrogen.

[0005] However, in some actual application scenarios, the rate of change between extreme temperatures is between 13K / min and 35K / min, and in severe cases it can exceed 35K / min. This rapid change between extreme temperatures is called temperature shock. Therefore, in order to evaluate the sealing performance of O-rings in high-pressure hydrogen systems, it is necessary to conduct tests on rubber O-rings in a hydrogen environment, such as high-pressure static test at extreme temperatures, high-pressure cycling test at extreme temperatures, temperature shock between extreme temperatures, and high-pressure pressure shock. Summary of the Invention

[0006] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one object of this invention is to provide an apparatus and method for testing the leakage of non-metallic seals under extreme operating conditions.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A non-metallic sealing component leakage testing device under high pressure includes a sealing component testing fixture, a pressure regulating system, a temperature regulating system, and a vacuum pump. The pressure regulating system includes a gas supply system and a pressurization system, which are sequentially connected via pipelines. The temperature regulating system includes a heat exchange medium connected to the sealing component testing fixture via pipelines. The sealing component testing fixture includes a base, an end plug, a pressure cap, and a heat-conducting pipe. The base and pressure cap cooperate to form a test chamber. The end plug is at least partially located within the test chamber. The sealing component to be tested is installed between the end plug and the base to form a seal. The end plug has an inner hole, and the sealing component to be tested is radially opposite to the inner hole. The heat-conducting pipe extends into the inner hole to form internal heat exchange. The heat-conducting pipe includes a heat exchange medium inlet and a heat exchange medium outlet. The vacuum pump is connected to the test chamber of the sealing component testing fixture and is used to evacuate the vacuum to meet the test requirements.

[0009] The test gas supplied by the gas supply system is pressurized by the pressurization system before being introduced into the sealing component testing fixture. The temperature regulation system uses internal heat exchange to allow direct convective heat exchange between the heat exchange medium and the sealing component testing fixture, enabling the testing device to meet the conditions of high and low temperature, high and low temperature shock, and high and low temperature cycle testing. The pressure regulation system enables the testing device to meet the conditions of high pressure, high pressure shock, and high pressure cycle testing. The gas supply system includes hydrogen cylinder groups or other gas cylinder groups, enabling the testing device to meet the conditions of sealing component leakage testing under extreme temperature conditions, extreme pressure conditions, and the combined action of hydrogen or other gases.

[0010] The heat exchange medium is preferably a hot or cold liquid medium. Compared with the combination of gas convection heat exchange and heat conduction, the combination of liquid convection heat exchange and heat conduction improves the heat exchange efficiency and shortens the test time.

[0011] Furthermore, the testing device also includes a vacuum detection chamber, which is connected to the sealing component testing fixture to collect leaked test gas for detecting the leakage rate of the test gas.

[0012] Furthermore, the base internally includes at least two stepped holes and a cap mounting hole from bottom to top, with the diameters of the at least two stepped holes increasing sequentially from bottom to top. The end plug includes at least two cylindrical segments with diameters increasing sequentially from bottom to top and a top mounting section. The diameter of the mounting section is smaller than the maximum diameter of the cylindrical segments. The lower part of the end plug is installed in the base, and the diameters of the cylindrical segments from bottom to top match the diameters of the stepped holes, so that a sealing installation gap is formed between the cylindrical segments of the end plug and the sidewalls of the stepped holes in the base. Specifically, the number of stepped holes and cylindrical segments is three.

[0013] Furthermore, the bottommost cylindrical segment has a first groove on its circumferential surface, and the seal to be tested is installed in the first groove. The seal to be tested forms a seal between the circumferential surface of the bottommost cylindrical segment and the sidewall of the bottommost stepped hole of the base. At least one other cylindrical segment has a second groove on its circumferential surface, and a radial seal is installed in the second groove. The radial seal forms a seal between the cylindrical segment and the corresponding sidewall of the stepped hole, preventing the test fixture from leaking gas axially when the seal to be tested fails.

[0014] Furthermore, a third groove is provided on at least one horizontal step surface of the at least two stepped holes, and an axial seal is provided in the third groove to prevent the detection gas entering the test fixture from leaking radially during the test.

[0015] Furthermore, the axial seal is an O-ring, and the radial seal is a combination of an O-ring / retaining ring and an O-ring. The retaining ring can improve the sealing ability of the radial seal O-ring.

[0016] Furthermore, the heat pipe sequentially includes a hexagonal boss section, a threaded connection section, and a baffle plate. The inner hole of the end plug sequentially includes a threaded hole and a blind hole from top to bottom. The threaded connection section is connected to the threaded hole, and the baffle plate extends into the blind hole. The hexagonal boss section protrudes from the end face of the end plug. The hexagonal boss section facilitates the installation and disassembly of the heat pipe, the threaded connection section facilitates the installation of the heat pipe in the inner hole of the end plug, and the baffle plate extends into the blind hole, allowing direct heat exchange with the test fixture. This results in better heat exchange performance, faster temperature change response, and enables the test device to meet the conditions for temperature shock testing.

[0017] Furthermore, the baffle plate of the heat pipe forms a unidirectional bent flow channel between the heat exchange medium inlet and the heat exchange medium outlet. The baffle plate can increase the flow path and flow time of the heat exchange medium, thereby improving the heat exchange effect.

[0018] Furthermore, the pressure cap includes an end cap and an insertion end, and the center of the pressure cap is a through hole. The mounting section of the end plug is clearance-fitted with the through hole, and the insertion end is inserted into the mounting hole of the pressure cap and restricts the axial movement of the end plug.

[0019] Furthermore, the bottom of the base is provided with a vent, which is connected to the gas supply system and serves as an inlet / outlet / vacuum port for the test gas.

[0020] Furthermore, the base is also provided with a connection port, which connects to the test chamber located between the seal to be tested and the radial seal, and at the same time, the connection port is connected to the vacuum testing chamber.

[0021] Furthermore, the vacuum detection chamber is equipped with a pressure sensor, a temperature sensor, and an air extraction port, which is used to evacuate the vacuum detection chamber.

[0022] Furthermore, the present invention also provides a test method using the above-mentioned non-metallic seal leakage test device under high pressure environment, the specific steps of which include: installing the seal to be tested in the first groove of the test fixture, and connecting the test fixture to the pressure regulation system and the temperature regulation system, wherein the gas supply system includes a hydrogen cylinder group and an argon cylinder group;

[0023] A vacuum pump was used to evacuate the test fixture, vacuum testing chamber, and connecting pipelines, so that the initial vacuum level of the vacuum testing chamber was 10. -2 Pa, then turn off the vacuum pump;

[0024] Turn on the argon cylinder group to purge the test fixtures and connecting pipelines with gas. After the purging is complete, turn off the argon cylinder group.

[0025] Leakage tests are conducted on the seals to be tested under the combined effects of temperature, pressure and hydrogen, including high / low temperature and high pressure hydrogen environment test, high and low temperature cycling test, temperature shock test, high pressure cycling test and pressure shock test;

[0026] Based on the data from the pressure and temperature sensors connected to the vacuum detection chamber, the mass leakage situation is obtained;

[0027] After the test is completed, the test pressure is released, the temperature control system is turned off, and after the test device returns to room temperature, the test fixture is disassembled, the seal to be tested is taken out to observe its microstructure and measure the changes in physical properties.

[0028] The present invention has the following beneficial effects:

[0029] (1) The test device of the present invention can meet the conditions of high / low temperature high pressure hydrogen environment test, high and low temperature temperature cycle test, temperature shock test, pressure cycle test, and pressure shock test, realize the leakage rate detection of non-metallic seals (such as O-rings) under the combined action of temperature, pressure and hydrogen, and meet the extreme service conditions of non-metallic seals under high pressure hydrogen environment.

[0030] (2) The built-in heating and cooling structure allows for direct convection heat exchange between the heat exchange medium and the sealing test fixture, resulting in better heat exchange and faster temperature change response, thus enabling the test device to meet the conditions for temperature shock testing.

[0031] (3) The end plug structure with non-metallic seals is directly installed in the test fixture base. The end plug is held in place by the bottom of the gland that is threaded to the base, ensuring that the end plug has no axial displacement inside the base, avoiding leakage caused by O-ring installation damage, and improving the accuracy of the test results.

[0032] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the non-metallic sealing leakage testing device under high pressure provided by the present invention;

[0034] Figure 2 This is a cross-sectional view of the sealing component testing fixture;

[0035] Figure 3 This is a three-dimensional structural cross-sectional view of the base;

[0036] Figure 4 This is a structural diagram of the retaining ring;

[0037] Figure 5 This is a diagram of a heat pipe structure;

[0038] Figure 6 This is a three-dimensional cross-sectional view of the heat pipe;

[0039] Figure 7 This is a three-dimensional cross-sectional view of the connection between the heat pipe and the end plug;

[0040] Figure 8 This is a structural diagram of the vacuum detection chamber;

[0041] Figure 9 It is the temperature change curve at the rubber O-ring seal structure being tested.

[0042] Explanation of reference numerals in the attached diagram: 1. Argon cylinder group; 2. Hydrogen cylinder group; 3. Pneumatic booster pump; 4. Control system; 5. Temperature regulation system; 6. Vacuum pump; 7. Sealing component testing fixture; 8. Vacuum detection chamber; 81. Vacuum detection chamber pressure sensor; 82. Vacuum detection chamber temperature sensor; 83. Ejector port; 84. Pipeline; 9. Heat conduction pipe; 91. Hexagonal boss section; 92. Threaded connection section; 93. Baffle plate; 94. Heat exchange medium inlet; 95. Heat exchange medium outlet; 10. Pressure cap; 11. End plug; 12. Axial sealing O-ring; 13. Retaining ring; 14. Radial sealing O-ring; 15. Rubber O-ring to be tested; 16. Base; 161. Vent; 162. Connection port; 163. Third groove. Detailed Implementation

[0043] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0044] Embodiments of the present invention will now be described with reference to the accompanying drawings.

[0045] Example 1:

[0046] like Figure 1 The diagram shows the non-metallic sealing component leakage testing device of this embodiment. The dashed lines represent signal lines of the control system, implemented as process pipelines. The testing device includes: a gas supply system, a pressurization system, a control system 4, a temperature regulation system 5, a vacuum pump 6, a sealing component testing fixture 7, and a vacuum detection chamber 8. The gas supply system consists of an argon cylinder group 1 and a hydrogen cylinder group 2. The pressurization system is specifically a pneumatic booster pump 3. The argon cylinder group 1, hydrogen cylinder group 2, and pneumatic booster pump 3 constitute the pressure regulation system of this embodiment. The argon cylinder group 1 is the replacement gas for the device and can also be replaced with other inert gases. The pneumatic booster pump 3 is equipped with a multi-stage booster pump to meet high-pressure requirements. Hydrogen in the hydrogen cylinder group 2 is delivered to the sealing component testing fixture 7 after reaching the test pressure value through the pneumatic booster pump 3. The control system 4 connects to the pressure and temperature sensors of each system via signal lines for real-time monitoring. The sealing component testing fixture 7 has an inlet pipe and an internal pressure in the vacuum detection chamber 8, and simultaneously monitors the temperature parameters of the heat exchange medium in the vacuum detection chamber 8 and the heat pipe 9 in real time; the temperature control system 5 heats or cools the sealing component testing fixture 7 through a liquid heat exchange medium; the vacuum pump 6 evacuates the sealing component testing fixture 7, the vacuum detection chamber 8, and the entire device piping; the sealing component testing fixture 7 is used to install the sealing component to be tested; the vacuum detection chamber 8 is connected to the sealing component testing fixture 7 and is used to collect hydrogen gas leaking from the sealing component to be tested, so as to detect hydrogen leakage.

[0047] In this embodiment, the seal to be tested is the rubber O-ring 15. The seal testing fixture 7 is designed for the sealing structure between the mouth of the vehicle-mounted hydrogen storage cylinder and the metal combination valve. It can also be used for static sealing structures such as fixed hydrogen storage containers and long-tube trailer cylinders. The material of the seal testing fixture is S31603 forging, but the material of the seal testing fixture can also be selected according to the actual sealing structure material.

[0048] The sealing component testing fixture is used to install the rubber O-ring 15 to be tested. Specifically, it includes a heat-conducting pipe 9, a gland 10, an end plug 11, an axial sealing O-ring 12, a retaining ring 13, a radial sealing O-ring 14, the rubber O-ring 15 to be tested, and a base 16. The base 16 and the gland 10 cooperate to form a test chamber, and the end plug 11 is installed in the test chamber.

[0049] The base 16 has a first step hole, a second step hole, a third step hole and a gland mounting hole arranged from bottom to top inside. The gland mounting hole is a threaded hole, and the diameter of the three step holes increases from bottom to top.

[0050] The end plug 11 is provided with a first cylindrical section, a second cylindrical section, a third cylindrical section and a top mounting section in sequence from bottom to top, wherein the mounting section is a long cylinder and the three cylindrical sections are short cylinders; the outer diameter of the three cylindrical sections increases sequentially from bottom to top.

[0051] When the end plug 11 is installed in the test chamber, the first cylindrical section is located in the first stepped hole, and the diameters of the two are equivalent. However, the axial length of the first cylindrical section is less than the axial depth of the first stepped hole, so that a cavity is formed between the bottom surface of the end plug 11 and the bottom surface of the inner hole of the base 16. The second cylindrical section is located in the second stepped hole, and the diameter and length of the second cylindrical section are equivalent to the inner diameter and depth of the second stepped hole. The third cylindrical section is located in the third stepped hole, and the diameter and length of the third cylindrical section are equivalent to the inner diameter and depth of the third stepped hole.

[0052] The outer circumferential surface of the first cylindrical section has a first groove, and the rubber O-ring 15 to be tested is installed in the first groove, forming a sealing structure between the outer circumferential surface of the first cylindrical section and the inner wall surface of the first stepped hole. The outer circumferential surface of the second cylindrical section has a second groove, and a radial seal is installed in the second groove, forming a sealing structure between the outer circumferential surface of the second cylindrical section and the inner wall surface of the second stepped hole. A third groove 163 is provided in the solid portion of the horizontal stepped surface between the second stepped hole and the third stepped hole for installing an axial sealing O-ring 12.

[0053] In this embodiment, the radial seals are specifically a retaining ring 13 and a radial sealing O-ring 14, wherein the retaining ring 13 can improve the sealing capability of the radial sealing O-ring 14. The tested rubber O-ring 15 can be made of rubber materials such as ethylene propylene diene monomer (EPDM), nitrile rubber (NBR), and fluororubber (FKM); the axial O-ring 12 and the radial sealing O-ring 14 are made of low-temperature resistant and high-pressure resistant rubber materials, including but not limited to FKM.

[0054] In this embodiment, the end plug 11 and the base 16 are sealed by a combination of axial sealing O-ring 12, radial sealing O-ring 14 and retaining ring 13. Under the premise of meeting the sealing requirements of the sealing test fixture 7, other embodiments may also use only the combination of radial sealing O-ring 14 and retaining ring 13, without the need to set axial sealing O-ring 12.

[0055] The cross-sectional shape of the retaining ring 13 is a right trapezoid, and the material is PTFE. The cross-sectional shape of the retaining ring 13 can also be rectangular, trapezoidal, triangular, etc., and the material includes but is not limited to PTFE, PEEK and other polymers.

[0056] The bottom of the base 16 is provided with a vent 161, which serves as a hydrogen inlet, a hydrogen outlet, and a vacuum port. The side of the base 16 is provided with a connection port 162 that connects to the vacuum detection chamber 8. The connection port 162 connects to the test chamber located between the rubber O-ring 15 to be tested and the radial seal. That is, in the hydrogen flow path, the connection port 162 is located downstream of the rubber O-ring 15 to be tested and upstream of the radial seal. At the same time, the connection port 162 is connected to the vacuum detection chamber to ensure that if a leak occurs at the rubber O-ring 15 to be tested, the leak can be detected by the vacuum detection chamber 8, and the leak will not flow out of the seal test fixture 7 under the action of the radial seal.

[0057] The end plug 11 has an inner hole at its center. The seal to be tested is opposite to the inner hole along the radial direction of the inner hole. The inner hole includes a threaded hole and a blind hole from top to bottom. The threaded hole is located in the installation section and is a large-diameter short threaded hole. Optionally, in this embodiment, the blind hole is a small-diameter long threaded hole.

[0058] The pressure cap 10 includes an end cap and an insertion end. The end cap includes a hexagonal section and a cylindrical section. The outer circumference of the hexagonal section is a hexahedron, which facilitates loading and unloading operations. The outer diameter of the cylindrical section is larger than the inner diameter of the pressure cap mounting hole of the base 16. The outer circumference of the insertion end is threaded and threadedly connected to the pressure cap mounting hole of the base 16.

[0059] The center of the pressure cap 10 is a through hole, the diameter of which is smaller than the diameter of the third cylindrical section of the end plug 11. The mounting section of the end plug 11 is clearance-fitted with the through hole, that is, the diameter of the through hole is slightly larger than the diameter of the mounting section of the end plug 11. The insertion end is inserted into the pressure cap mounting hole of the base 16. The third cylinder is restricted by the end face of the insertion end, thus suppressing the axial movement of the end plug 11, achieving the function of fixing the end plug 11, avoiding leakage caused by installation damage, and improving the accuracy of leakage test results.

[0060] The heat pipe 9 includes, from top to bottom, a hexagonal boss section 91, a threaded connection section 92, and a baffle plate 93. The threaded connection section 92 is threadedly connected to the threaded hole of the end plug 11. The hexagonal boss section 91 protrudes from the upper end face of the end plug 11 for easy disassembly and assembly, while the baffle plate 93 extends into the blind hole. The hexagonal boss section 91 and the threaded connection section 92 are provided with two mutually spaced through holes, which serve as the heat exchange medium inlet and the heat exchange medium outlet, respectively. In this embodiment, the baffle 93 is also located between the heat exchange medium inlet and the heat exchange medium outlet, and its length is less than the length of the blind orifice. The blind orifice serves as a flow channel for the heat exchange medium. The baffle 93 divides the blind orifice into two flow channels, one of which is directly connected to the heat exchange medium inlet, and the other is directly connected to the heat exchange medium outlet. These two flow channels form a bend at the end of the baffle 93. The heat exchange medium entering from the heat exchange medium inlet is blocked by the baffle 93 and flows along one of the flow channels. When it reaches the end of the baffle 93, it is deflected and flows out through the heat exchange medium outlet after reaching the other flow channel. In this embodiment, the blind orifice uses a small-diameter long threaded hole to increase the convective heat transfer area and enhance the heat transfer effect. In other embodiments, an odd number of baffles greater than 1 can be set according to the heat transfer intensity requirements.

[0061] The vacuum testing chamber 8 is equipped with a pressure sensor 81, a temperature sensor 82, and a vacuum port 83, which is used for evacuation. The vacuum testing chamber 8 is connected to the sealing component testing fixture 7 via a pipe 84. The volume V of the vacuum testing chamber 8 is constant. The pressure P and temperature T measured by the pressure sensor 81 and the temperature sensor 82 are recorded. The leakage rate of the tested rubber O-ring 15 is calculated according to the ideal gas law PV = mRT.

[0062] The non-metallic seal leakage testing device under high pressure in this embodiment is used to conduct high and low temperature shock tests and hydrogen leakage tests under extreme pressure conditions on the O-ring 15. The heat exchange media are high-temperature heat transfer oil and low-temperature heat transfer oil, respectively. The heat exchange medium inlet 94 and heat exchange medium outlet 95 are connected to two-way valves, one channel of which connects to the high-temperature heat transfer oil, and the other channel connects to the low-temperature heat transfer oil. Simultaneously with the high and low temperature shock test, the pressure test conditions can be constant high pressure and high-pressure shock, depending on the service conditions. It is worth noting that the pressure rise and fall time of the high-pressure shock test should be consistent with the temperature rise and fall time of the high and low temperature shock test.

[0063] Operating procedures for leakage testing of rubber O-ring 15 under high and low temperature shock and extreme pressure conditions:

[0064] (1) Before the test, install the rubber O-ring 15 to be tested in the sealing test fixture 7 and connect the device system;

[0065] (2) During the test, vacuum pump 6 was used to evacuate the sealing component testing fixture 7, the vacuum detection chamber 8, and the connecting pipeline. Then, vacuum pump 6 was turned off, and the initial vacuum level of the vacuum detection chamber 8 was 10. -2 Pa; After the vacuuming is completed, turn on the argon cylinder group 1 to perform gas replacement on the sealing component test fixture 7 and pipeline. After the replacement is completed, turn off the argon cylinder group 1.

[0066] (3) Start the leakage test under the combined action of temperature, pressure and hydrogen. First, turn on the temperature regulation system 5 and introduce low temperature heat transfer oil into the sealing component test fixture 7 to lower the test temperature to a low temperature. At the same time, turn on the pressure regulation system and open the hydrogen cylinder 2. After the hydrogen reaches the high pressure test value through the pneumatic booster pump 3, it is delivered to the sealing component test fixture 7. When the low temperature heat transfer oil is introduced into the sealing component test fixture 7, the high temperature heat transfer oil is heated to the set high temperature value in the temperature regulation system 5.

[0067] (4) After the temperature and pressure reach the set point, let it stand for a period of time. If there is no obvious leakage, then proceed with the subsequent test. Otherwise, the rubber O-ring 15 tested on the surface is not suitable for low temperature and high pressure hydrogen environment, and the test should be terminated.

[0068] (5) In subsequent tests, high-temperature heat transfer oil was introduced into the sealing component test fixture 7 to heat it internally. The temperature of the tested rubber O-ring 15 reached the expected high temperature value within a specified time.

[0069] (6) Low-temperature heat transfer oil is introduced into the sealing component testing fixture 7 again to cool its internal temperature. High-temperature heat transfer oil and low-temperature heat transfer oil are circulated into the sealing component testing fixture 7 to achieve temperature shock of the tested O-ring 15.

[0070] (7) Record the data of pressure sensor 81 and temperature sensor 82 in vacuum detection chamber 8, and calculate the leakage of rubber O-ring 15 under test.

[0071] Example 2:

[0072] This embodiment uses the sealing structure of the metal boss at the mouth of a vehicle-mounted Type IV hydrogen storage cylinder and the metal combination valve as the test structure. The tested rubber O-ring 15 has specifications of φ30.0mm×3.55mm, a compression rate of 20%, and is made of EPDM, FKM, and NBR rubbers. The leakage of the tested rubber O-ring 15 under extreme operating conditions—temperature shock, high pressure shock, and the combined action of hydrogen—is measured using a rubber O-ring hydrogen leakage detection device. Argon cylinder group 1 and hydrogen cylinder group 2 are connected to a pneumatic booster pump 3. Before the test, the pipeline system is purged using argon cylinder group 1. During the test, high-pressure hydrogen is delivered to the sealing ring testing fixture 7 via the pneumatic booster pump 3. The hydrogen pressure range is 0–87.5MPa, the rate of change between extreme pressures is 25MPa / min, and the pressure control accuracy is ±1MPa. Vacuum pump 6 connects to the gas supply line of sealing component testing fixture 7 and vacuum detection chamber 8. Vacuum pump 6 can ensure that the vacuum level of sealing component testing fixture 7 and vacuum detection chamber 8 reaches the set value. Temperature control system 5 is connected to the heat exchange medium inlet and outlet of sealing component testing fixture 7, forming a built-in heating structure. It controls the temperature change at the sealing structure from -40 to 85℃ through a combination of fluid convection heat transfer and heat conduction, with the rate of change between extreme temperatures ≤40℃ / min, and the temperature control accuracy of the heat exchange medium is ±0.5℃. The heat exchange media are high-temperature heat transfer oil and low-temperature heat transfer oil. A constant high-temperature heat transfer oil (70℃) and a constant low-temperature heat transfer oil (-45℃) are circulated through the sealing component testing fixture 7 to internally heat and cool it, achieving temperature shock to the tested rubber O-ring 15. Figure 9 As shown, the tested rubber O-ring 15 seal structure underwent one temperature shock, with the temperature dropping from 65℃ to -40℃ within a specified time of 180s, and then rising back to 65℃ under the action of high-temperature heat transfer oil.

[0073] Vacuum testing chamber 8 and sealing ring testing fixture 7 are connected by pipe 84, with an initial vacuum level of 10. -2 Pa, volume 10L, pressure sensor measurement range 10 -2 ~2×10 5 Pa.

[0074] Operating procedures for testing the leakage rate of rubber O-rings used to seal the metal cylinder valve seat and metal combination valve of a vehicle-mounted Type IV hydrogen storage cylinder:

[0075] (1) Install the rubber O-ring 15 to be tested on the first cylindrical section of the end plug 11, install the radial sealing O-ring 14 and the retaining ring 13 on the second cylindrical section of the end plug 11, install the axial sealing O-ring 12 in the third groove 163 of the end plug 11, thread the heat conduction tube 9 to the end plug 11, and then install the end plug 11 and the pressure cap 10 in sequence inside the base 16. The base 16 is connected to the pressure regulating system and the vacuum detection chamber 8 respectively.

[0076] (2) Use vacuum pump 6 to evacuate the sealing component testing fixture 7, vacuum detection chamber 8, and connecting pipelines, then turn off vacuum pump 6. The initial vacuum level of vacuum detection chamber 8 is 10. -2 Pa;

[0077] (3) Turn on the argon cylinder group 1 and perform gas replacement on the sealing component test fixture 7 and pipeline. After the replacement is completed, turn off the argon cylinder group 1.

[0078] (4) Turn on the temperature control system 5 and conduct a temperature shock test. Set the temperature change range at the sealing structure to -40 to 65℃ and the rate of change between extreme temperatures to 35K / min.

[0079] (5) Turn on the hydrogen cylinder group 2 and the pneumatic booster pump 3 to conduct a pressure shock test. Adjust the test pressure change range to 0.5-70MPa and the rate of change between the ultimate pressures to 23MPa / min.

[0080] (6) The pressure P (Pa) and temperature T (K) of hydrogen gas during the test are measured using pressure sensor 81 and temperature sensor 82 connected to the vacuum detection chamber 8. Based on PV = nRT, the formula for calculating the mass leakage rate is:

[0081] (7) After the test is completed, open the pressure relief valve on the connecting pipeline of the sealing test fixture 7 to remove the test pressure; at the same time, close the temperature regulation system 5 and wait for the temperature of the test device to return to room temperature; disassemble the sealing ring test fixture 7, take out the rubber O-ring 15 to be tested, observe its micro morphology and measure the changes in physical property parameters.

[0082] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0083] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0084] Furthermore, the terms "first," "second," etc., used in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance, or implicitly specifying the number of technical features indicated in this embodiment. Therefore, features defined with terms such as "first" and "second" in the embodiments of this invention can explicitly or implicitly indicate that the embodiment includes at least one of those features. In the description of this invention, the word "multiple" means at least two or more, such as two, three, four, etc., unless otherwise explicitly specified in the embodiments.

[0085] In this invention, unless otherwise explicitly specified or limited in the embodiments, the terms "installation," "connection," "joining," and "fixing" appearing in the embodiments should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral part; it can also be a mechanical connection, an electrical connection, etc. Of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components, or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific implementation.

[0086] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0087] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A non-metallic seal leakage testing device under high pressure, comprising a seal testing fixture (7), a pressure regulating system, a temperature regulating system (5), and a vacuum pump (6); characterized in that: The pressure regulation system includes an air supply system and a pressurization system, and the air supply system, the pressurization system, and the sealing component testing fixture (7) are connected in sequence through pipelines. The temperature control system (5) includes a heat exchange medium, which is connected to the sealing test fixture (7) through a pipeline; The sealing component testing fixture (7) includes a base (16), an end plug (11), a pressure cap (10), and a heat-conducting pipe (9). The base (16) and the pressure cap (10) cooperate to form a test chamber. The end plug (11) is at least partially located in the test chamber. The sealing component to be tested is installed between the end plug (11) and the base (16) to form a seal. The end plug (11) has an inner hole. The sealing component to be tested is opposite to the inner hole along the radial direction of the inner hole. The heat-conducting pipe (9) extends into the inner hole and forms an internal heat exchange with the end plug (11) and the sealing component to be tested. The heat-conducting pipe (9) includes a heat exchange medium inlet (94) and a heat exchange medium outlet (95). The vacuum pump (6) is connected to the test chamber of the sealing component test fixture (7).

2. The non-metallic sealing leakage testing device under high pressure environment according to claim 1, characterized in that: It also includes a vacuum detection chamber (8), which is connected to the sealing test fixture (7) to collect leaked test gas.

3. The non-metallic sealing leakage testing device under high pressure environment according to claim 2, characterized in that: The base (16) includes at least two stepped holes and a pressure cap mounting hole from bottom to top, and the diameter of the at least two stepped holes increases from bottom to top.

4. The non-metallic seal leakage testing device under high pressure environment according to claim 3, characterized in that: The end plug (11) includes at least two cylindrical segments with diameters increasing sequentially from bottom to top and a top mounting segment, the diameter of which is smaller than the maximum diameter of the cylindrical segments.

5. The non-metallic seal leakage testing device under high pressure environment according to claim 4, characterized in that: The bottom cylindrical section has a first groove on its circumference, and the seal to be tested is installed in the first groove. At least one other cylindrical section has a second groove on its circumference, and a radial seal is installed in the second groove.

6. The non-metallic seal leakage testing device under high pressure environment according to claim 5, characterized in that: A third groove (163) is provided on at least one horizontal step surface of the at least two stepped holes, and an axial seal is provided in the third groove.

7. The non-metallic seal leakage testing device under high pressure environment according to claim 6, characterized in that: The axial seal is an O-ring, and the radial seal is a combination of an O-ring / retaining ring (13) and an O-ring.

8. The non-metallic seal leakage testing device under high pressure environment according to claim 4, characterized in that: The number of stepped holes and cylindrical segments is 3.

9. The non-metallic seal leakage testing device under high pressure environment according to claim 8, characterized in that: The heat pipe (9) includes a hexagonal boss section (91), a threaded connection section (92), and a baffle plate (93) in sequence. The inner hole of the end plug includes a threaded hole and a blind hole in sequence from top to bottom. The threaded connection section is connected to the threaded hole. The baffle plate extends into the blind hole. The hexagonal boss section protrudes from the end face of the end plug.

10. The non-metallic seal leakage testing device under high pressure environment according to claim 9, characterized in that: The baffle (93) of the heat pipe (9) forms a unidirectional bent flow channel between the heat exchange medium inlet (94) and the heat exchange medium outlet (95).

11. The non-metallic seal leakage testing device under high pressure environment according to claim 4, characterized in that: The pressure cap (10) includes an end cap and an insertion end, and the center of the pressure cap is a through hole. The mounting section of the end plug (11) is clearance-fitted with the through hole. The insertion end is inserted into the mounting hole of the pressure cap and restricts the axial movement of the end plug (11).

12. The non-metallic seal leakage testing device under high pressure environment according to claim 5 or 6, characterized in that: The bottom of the base (16) is provided with a vent (161), which is connected to the gas supply system as an inlet / outlet / vacuum port for the test gas.

13. The non-metallic seal leakage testing device under high pressure environment according to claim 5 or 6, characterized in that: The base (16) is also provided with a connection port (162), which connects to the test cavity located between the seal to be tested and the radial seal, and at the same time, the connection port (162) connects to the vacuum testing cavity (8).

14. The non-metallic seal leakage testing device under high pressure environment according to claim 13, characterized in that: The vacuum detection chamber (8) is equipped with a pressure sensor (81), a temperature sensor (82), and an air extraction port (83).

15. A test method using the non-metallic seal leakage test device under high pressure environment as described in claim 13 or 14, characterized in that: The seal to be tested is installed in the first groove of the test fixture (7), and the test fixture (7) is connected to the pressure regulation system and the temperature regulation system (5). The gas supply system includes a hydrogen cylinder group (2) and an argon cylinder group (2). The test fixture (7), vacuum detection chamber (8), and connecting pipelines are evacuated using a vacuum pump (6) to achieve an initial vacuum level of 10 in the vacuum detection chamber (8). -2 Pa, then turn off the vacuum pump (6); Turn on the argon cylinder group (2) and perform gas replacement on the test fixture (7) and connecting pipeline. After the replacement is completed, turn off the argon cylinder group (2). Leakage tests are conducted on the seals to be tested under the combined effects of temperature, pressure, and hydrogen, including high / low temperature and high pressure hydrogen environment tests, high and low temperature cycling tests, temperature shock tests, pressure cycling tests, and pressure shock tests. Based on the data from the pressure sensor (81) and temperature sensor (82) connected to the vacuum detection chamber (8), the mass leakage situation is obtained; After the test is completed, the test pressure is released, the temperature control system is turned off, and after the test device returns to room temperature, the test fixture is disassembled, the seal to be tested is taken out to observe its morphological changes and measure the changes in physical property parameters.

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