A cryogenic sealing device and its manufacturing method

Abstract

This invention relates to the field of sealing and discloses a low-temperature sealing device and its manufacturing method. The low-temperature sealing device includes: a bottle valve seat with an outer bottle opening on its top side and a connecting shell on the outer side of the bottle valve seat, the connecting shell protruding upward from the bottle valve seat; a sealing plug with a sealing platform formed on its bottom side and an inner plug body formed on the bottom side of the sealing platform, the sealing platform being connected to the connecting shell and the inner plug body being connected to the inner side of the bottle valve seat, a first groove being formed between the bottom side of the sealing platform and the top side of the bottle valve seat; and an end-face sealing assembly including an inner sealing element, an expansion part, and an outer sealing assembly. The outer sealing assembly can press against the expansion part, causing the expansion part to press against the sealing platform and the bottle valve seat in the vertical direction. This invention forms a triple seal with the inner sealing element, the expansion part, and the outer sealing assembly. When gas leakage occurs, the expansion part can be pressed against the bottle valve seat from both inside and outside, further compensating for the gap between the sealing platform and the bottle valve seat, thereby effectively improving the sealing effect.

Description

Technical Field

[0001] This invention relates to the field of sealing, and discloses a low-temperature sealing device and its manufacturing method. Background Technology

[0002] The on-board high-pressure hydrogen storage system is a key component of hydrogen fuel cell vehicles, and its sealing performance directly determines driving safety and operational efficiency. Currently, mainstream 70MPa Type IV hydrogen storage cylinders typically employ a plastic inner liner and metal valve assembly structure. The sealing system primarily uses perfluoroelastomer rubber O-rings, metal C-rings, or a combination of both. However, in extremely cold regions, such as Northeast and Northwest my country, or under rapid cooling conditions (down to -60°C) caused by rapid hydrogen charging and discharging, the deformation difference between the metal valve seat, plastic inner liner, and plastic seals is significant. At -60°C, the sealing gap increases compared to room temperature, significantly increasing the risk of leakage failure for commonly used sealing methods such as overflow grooves, limiting grooves, and meshing grooves within the hydrogen storage cylinder. To further address gap compensation, currently used single-spring compensation mechanisms may be severely insufficient compared to room temperature conditions. Furthermore, the increased viscosity and reduced fluidity of lubricating grease at low temperatures further affect the compensation effect. Therefore, a structure with better low-temperature sealing is urgently needed. Summary of the Invention

[0003] The purpose of this invention is to provide a cryogenic sealing device and manufacturing method to solve one or more technical problems existing in the prior art, and at least provide a beneficial option or create conditions.

[0004] A cryogenic sealing device according to a first aspect of the present invention includes: a bottle valve seat with an outer bottle opening on its top side, a connecting shell on the outer side of the bottle valve seat, the connecting shell protruding upward from the bottle valve seat; a sealing plug with a sealing platform formed on its bottom side, an inner plug body formed on the bottom side of the sealing platform, the sealing platform being connected to the inner side of the portion of the connecting shell protruding upward from the bottle valve seat, the inner plug body being inserted into the outer bottle opening and connected to the inner side of the bottle valve seat, a first groove being formed between the bottom side of the sealing platform and the top side of the bottle valve seat; and an end face sealing assembly disposed in the first groove, the end face sealing assembly including an inner sealing element, a tightening part, and an outer sealing assembly arranged sequentially in a direction away from the inner plug body, the outer sealing assembly being able to press against the tightening part and cause the tightening part to press against the sealing platform and the bottle valve seat in a vertical direction.

[0005] This technical solution has at least the following beneficial effects: The valve seat is installed at the mouth of the hydrogen storage cylinder. A connecting shell is provided on the outside of the valve seat. When assembling the sealing plug, the inner plug body of the sealing plug is inserted into the valve seat from the outer bottle mouth, so that the inner side of the inner plug body is connected to the inner side of the valve seat. The sealing platform and the part of the connecting shell that protrudes upward from the valve seat are connected to each other. At this time, a double connection is formed between the sealing plug and the valve seat. An end face sealing assembly is provided between the inner and outer connection positions. In the end face sealing assembly, the inner sealing element, the tightening part, and the outer sealing assembly itself form a triple seal from the inside to the outside. When leakage occurs between the inner plug body and the valve seat, the leaked gas flows to the inner sealing element, which then seals the inner seal. The seal pushes outward against the tightening part, and the outer sealing assembly also presses against the tightening part. Under the internal and external pressure of the inner and outer seals, the tightening part expands and increases in the vertical direction, further pressing against the sealing platform and the bottle valve seat in the vertical direction. Since there is a double connection between the sealing plug and the bottle valve seat, it can effectively prevent the sealing plug and the bottle valve seat from being pulled on both sides of the end face sealing assembly, thus increasing the gap and ensuring the sealing performance of the bottle valve seat. In this way, the inner seal, the tightening part and the outer sealing assembly form a triple seal. When gas leakage occurs, the tightening part can be pressed from the inside and outside, and the tightening part can further compensate for the gap between the sealing platform and the bottle valve seat, thereby effectively improving the sealing effect.

[0006] According to some embodiments of the present invention, the external sealing assembly includes memory alloy wires and spring wires connected in series, the memory alloy wires and the spring wires abutting against the outer side of the tightening portion.

[0007] According to some embodiments of the present invention, a hydrogen content sensor is provided between the sealing platform and the bottle valve seat, the hydrogen content sensor being used to detect the hydrogen content leaking between the sealing platform and the bottle valve seat, and the cryogenic sealing device further includes a cooler configured to cool the shape memory wire based on the detection value of the hydrogen content sensor.

[0008] According to some embodiments of the present invention, the tightening portion includes a first wedge ring abutting against the outer side of the inner seal and a second wedge ring abutting against the inner side of the outer seal assembly. A first inclined surface is formed on the outer side of the first wedge ring, and a second inclined surface is formed on the inner side of the second wedge ring. The first inclined surface abuts against the second inclined surface, and the elastic modulus of the first wedge ring is greater than that of the second wedge ring.

[0009] According to some embodiments of the present invention, the first inclined surface is provided with a honeycomb microtexture.

[0010] According to some embodiments of the present invention, a second groove is formed between the bottom side of the sealing platform and the top side of the bottle valve seat. The second groove is spaced apart from the first groove on the side away from the center of the inner plug body. The end face sealing assembly further includes an inner elastic frame and an outer elastic layer formed on the outer surface of the inner elastic frame. The inner elastic frame is arc-shaped with its opening facing the inner plug body. The upper and lower sides of the outer elastic layer abut against the sealing platform and the bottle valve seat, respectively. The inner elastic frame and the outer elastic layer are respectively arranged around the inner plug body. An annular groove is formed on the inner side of the outer elastic layer corresponding to the position of the arc-shaped opening of the inner elastic frame.

[0011] According to some embodiments of the present invention, the present invention further includes a side sealing assembly, the side sealing assembly including a top pressure ring and an elastic ring, an annular sealing groove is provided on the outer side of the inner plug, the upper sidewall of the annular sealing groove extends upward in a direction away from the center of the inner plug, the elastic ring and the top pressure ring are disposed in the annular sealing groove from top to bottom, and the top side of the elastic ring is in close contact with the upper sidewall of the annular sealing groove.

[0012] According to some embodiments of the present invention, the outer side of the bottle valve seat is provided with a narrowing section, the outer radial direction of the narrowing section gradually decreases downward, the bottom of the connecting shell is provided with an outer sealing ring, the outer sealing ring abuts against the outer side of the narrowing section, and the outer side of the sealing platform is threadedly connected to the inner side of the top of the connecting shell.

[0013] A method for manufacturing a cryogenic sealing device according to a second aspect of the present invention, comprising:

[0014] The first wedge-shaped ring was formed by metal additive manufacturing;

[0015] The first inclined surface of the first wedge-shaped ring is processed with a honeycomb microtexture using laser processing;

[0016] The first wedge ring is subjected to hot isostatic pressing;

[0017] A zirconium-doped nanocoating is deposited on the first inclined surface of the first wedge ring, covering the interior of the honeycomb microtexture.

[0018] This technical solution has at least the following beneficial effects: the first wedge ring, after being formed, undergoes laser processing to create a honeycomb microtexture, which increases the contact area with the second wedge ring and enhances sealing stability. Furthermore, it can accommodate minute impurities on the sealing surface, preventing scratches. The processed microtexture can simultaneously improve sealing stability by increasing the contact area and protecting the sealing surface. Subsequently, hot isostatic pressing (HIP) is used to eliminate internal micropores generated during metal additive manufacturing. A zirconium-doped nanocoating covers the first inclined surface of the first wedge ring and the interior of the microtexture. The zirconium enhances the coating's density, thereby improving its resistance to hydrogen permeation. This effectively improves the structural stability of the first wedge ring and strengthens the tightness of the fit between the first and second wedge rings, effectively reducing the safety risks caused by hydrogen leakage in extremely cold regions.

[0019] A method for manufacturing a cryogenic sealing device, comprising:

[0020] In an environment not exceeding -60℃, the sealing plug and the bottle valve seat are connected by gradually increasing torque, and after the previous increase in torque, the temperature is maintained before the next increase in torque is performed.

[0021] This technical solution has at least the following beneficial effects: Due to the difference in the coefficient of linear expansion between the sealing structure materials, there is a hysteresis effect in the thermal shrinkage deformation of each component at low temperature. In order to fully compensate for the thermal shrinkage deformation, and considering that the one-time pre-tightening has caused uneven fit of the sealing surface, the strain generated by each level of pre-tightening is fully released by heat preservation for a sufficient period of time. This can effectively ensure the sealing performance during assembly and prevent leakage caused by insufficient pre-tightening force when used in low temperature environment.

[0022] 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

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly explained below. Obviously, the described drawings are only a part of the embodiments of the present invention, and not all of them. Those skilled in the art can obtain other design schemes and drawings based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the low-temperature sealing device of the present invention.

[0025] Figure 2 yes Figure 1 A magnified view of part A.

[0026] In the attached diagram: 100-bottle valve seat, 110-connecting shell, 120-narrowing section, 130-outer sealing ring, 200-sealing plug, 210-sealing platform, 220-inner plug body, 221-annular sealing groove, 230-first groove, 240-second groove, 310-inner sealing element, 320-outer sealing assembly, 330-hydrogen content sensor, 341-first wedge ring, 342-second wedge ring, 351-inner elastic frame, 352-outer elastic layer, 410-top pressure ring, 420-elastic ring. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown 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 are only used to explain the present invention, and should not be construed as limiting the present invention.

[0028] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not 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 limiting this invention.

[0029] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0030] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0031] In the description of this application, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0032] In the description of this application, the use of terms such as "one embodiment," "some embodiments," "an example," "some instances," "some embodiments," "illustrative embodiment," "example," "specific example," and "some examples" indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. 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.

[0033] Reference Figure 1 and Figure 2 According to a first aspect of the present invention, a cryogenic sealing device includes a bottle valve seat 100, a sealing plug 200, and an end face sealing assembly. The bottle valve seat 100 has an outer bottle opening on its top side, and a connecting shell 110 is provided on the outer side of the bottle valve seat 100, the connecting shell 110 protruding upwards from the bottle valve seat 100. A sealing platform 210 is formed on the bottom side of the sealing plug 200, and an inner plug body 220 is formed on the bottom side of the sealing platform 210. The sealing platform 210 is connected to the inner side of the portion of the connecting shell 110 protruding upwards from the bottle valve seat 100, and the inner plug body 220 is inserted into the outer bottle opening and connected to the bottle valve seat. On the inner side of 100, a first groove 230 is formed between the bottom side of the sealing platform 210 and the top side of the bottle valve seat 100; the end face sealing assembly is disposed in the first groove 230, and the end face sealing assembly includes an inner sealing element 310, an expansion part and an outer sealing assembly 320 arranged sequentially in a direction away from the inner plug body 220. The outer sealing assembly 320 can press against the expansion part and cause the expansion part to press against the sealing platform 210 and the bottle valve seat 100 in the up and down direction. In practical applications, the inner sealing element 310 is an elastic sealing element that can elastically expand outward when compressed, thereby squeezing the expansion part.

[0034] As described above, the valve seat 100 is used to install onto the neck of the hydrogen storage cylinder. A connecting shell 110 is provided on the outer side of the valve seat 100. When assembling the sealing plug 200, the inner plug body 220 of the sealing plug 200 is inserted into the valve seat 100 from the outer neck, so that the inner side of the inner plug body 220 is connected to the inner side of the valve seat 100. The sealing platform 210 and the part of the connecting shell 110 that protrudes upward from the valve seat 100 are connected to each other. At this time, the sealing plug 200 and the valve seat 100 form a double connection, and an end face sealing assembly is provided between the inner and outer connection positions. In the end face sealing assembly, the inner sealing element 310, the tightening part, and the outer sealing assembly 320 itself form a triple seal from the inside to the outside. When leakage occurs between the inner plug body 220 and the valve seat 100, the leaked gas flows to the inner sealing element 310, which... The inner seal 310 presses outward against the tightening part, while the outer sealing assembly 320 also presses against the tightening part. Under the internal and external pressure of the inner seal 310 and the outer seal, the tightening part expands and increases in the vertical direction, further pressing against the sealing platform 210 and the bottle valve seat 100 in the vertical direction. Since the sealing plug 200 and the bottle valve seat 100 have a double connection, it can effectively prevent the sealing plug 200 and the bottle valve seat 100 from being pulled on both sides of the end face sealing assembly, thus increasing the gap and ensuring the sealing performance of the inside of the bottle valve seat 100. In this way, the inner seal 310, the tightening part and the outer sealing assembly 320 form a triple seal. When gas leakage occurs, the tightening part can be pressed from the inside and outside directions to further compensate for the gap between the sealing platform 210 and the bottle valve seat 100, thereby effectively improving the sealing effect.

[0035] In a specific embodiment of the external sealing assembly 320, the external sealing assembly 320 includes a shape memory alloy wire and a spring wire connected in series. The shape memory alloy wire and the spring wire are connected in series and abut against the outside of the expansion joint. When low-temperature gas leaks and reaches the position of the external sealing assembly 320, the shape memory alloy wire contracts upon cooling, pulling the spring wire inward and squeezing the expansion joint inward, thereby achieving precise compensation of the sealing surface gap and reducing the leakage rate.

[0036] By connecting a shape memory alloy wire and a stainless steel spring in series, the linear elastic force of the spring compensates for the nonlinear deviation of the shape memory alloy. This allows the linkage mechanism formed by the shape memory alloy and the spring wire to achieve a single-pass memory effect of ≥6% and a total compensation of ≥0.6 mm at -60℃, effectively widening the maximum compensation gap. Furthermore, the mechanism's response time is shorter than that of a single shape memory alloy drive, meeting the real-time requirements of automotive applications. Preferably, Ni is selected as the shape memory alloy wire. 55 Ti 44 Cr1 alloy wire (-60℃ and below) or Ni 47 Ti 44Nb9 (-196℃ and below) ultra-low temperature shape memory alloy wire is used, while 316L stainless steel springs can be selected as the spring wire. A mounting groove can be provided on the outside of the expansion joint, with the diameter of the shape memory alloy wire and the stainless steel spring matching the width of the mounting groove. The total length of the shape memory alloy wire connected in series with the stainless steel spring is adapted to the circumferential installation space of the valve seat 100. The sum of the shape memory alloy's shrinkage and stretching amounts matches the shrinkage gap of the non-metallic wedge seal at low temperatures, achieving precise compensation for the sealing surface gap. The two ends of the linkage mechanism formed by the shape memory alloy and the spring wire are connected and fixed in the mounting groove on the outside of the expansion joint via threaded joints. The preload of the linkage mechanism formed by the shape memory alloy and the spring wire is adjusted by rotating the threaded joints, with an adjustment range of 75%~125% of the design value and a response time ≤100ms, enabling rapid compensation for the sealing surface gap at low temperatures.

[0037] The above-mentioned passive compensation is mainly achieved through cryogenic gas leakage. In addition, active compensation is also possible. Specifically, a hydrogen content sensor 330 is installed between the sealing platform 210 and the bottle valve seat 100. The hydrogen content sensor 330 is used to detect the hydrogen content leaking through the gap between the sealing platform 210 and the bottle valve seat 100. The cryogenic sealing device also includes a cooler, which is configured to cool the shape memory alloy wire based on the detection value of the hydrogen content sensor 330. In practical applications, a semiconductor cooler can be used, transferring cooling energy to the internal shape memory alloy wire through the sealing plug 200. When the hydrogen content sensor 330 detects outward hydrogen leakage, the cooler receives the signal and cools the shape memory alloy wire. The cooled shape memory alloy wire contracts, tightening the spring wire and pressing inward against the expansion joint, thus achieving active gap compensation. Additionally, FBG strain sensors can be embedded in the sealing stage 210 at the position corresponding to the outer sealing component 320. The FBG strain sensor has a center wavelength of 1550 nm ± 5 nm and is installed in the sealing stage 210 with low-temperature epoxy adhesive (bonding strength ≥ 8 MPa at -60℃). Four or more even-numbered sensors are evenly distributed circumferentially, with a sampling frequency of 100 Hz and a strain resolution ≤ 0.001%. The hydrogen content sensor 330 is a Pd-Ag-Pt alloy hydrogen sensor with an alloy film thickness of 500 nm. It is vacuum-encapsulated with titanium alloy Ti-6Al-4V and has built-in miniature low-power heating elements (power ≤ 50 mW). The number of these elements is not less than two, with a detection range of 0.05%~1% vol and a response time ≤ 30 ms.

[0038] The tightening part is compressed to increase in height along the vertical direction under internal and external pressure, which can be achieved by directly using an elastic material. In this embodiment, the tightening part includes a first wedge ring 341 abutting against the outer side of the inner seal 310 and a second wedge ring 342 abutting against the inner side of the outer seal assembly 320. The outer side of the first wedge ring 341 has a first inclined surface, and the inner side of the second wedge ring 342 has a second inclined surface. The first inclined surface abuts against the second inclined surface. The elastic modulus of the first wedge ring 341 is greater than that of the second wedge ring 342. In practical applications, the first wedge ring 341 can be made of metal, while the second wedge ring 342 can be made of non-metallic material. Both can produce elastic deformation. When a gas leak occurs, the gas compresses the first wedge ring 341. Since the first wedge ring 341 has a large elastic modulus, it mainly undergoes radial elastic deformation under pressure, and then compresses the second wedge ring 342. With the guidance of the first and second inclined surfaces, the second wedge ring 342 with a smaller elastic modulus is compressed upward, thereby increasing the top pressure on the sealing platform 210 and the bottle valve seat 100 in the vertical direction and improving the effect of gap compensation.

[0039] When the entire cryogenic sealing device is applied to the vehicle interior, a Kalman filter data fusion and early warning model can be built into the vehicle's controller. Monitoring data is connected to the vehicle controller via a CAN bus, fusing five dimensions of data: temperature (accuracy ±0.5℃), pressure (accuracy ±0.1MPa), strain, hydrogen concentration, and shape memory wire shrinkage. The failure prediction accuracy is ≥99%. Testing and verification: When a strain deviation >3% (relative to the initial preload strain value) or hydrogen concentration >0.1% vol is detected, the vehicle controller controls the shape memory wire-spring wire to compensate by 5% of the design compensation amount each time. This results in a more pronounced compression deformation of the second wedge ring 342, leading to a tighter seal until the hydrogen concentration returns to the normal range. Through active sealing compensation, the leakage rate can be further reduced to 10%. - ¹¹Pa·m³ / s.

[0040] To enhance the functionality of the first wedge ring 341, in this embodiment, the first inclined surface is provided with a honeycomb microtexture. The honeycomb microtexture increases the contact area with the second inclined sealing surface, thereby increasing sealing stability. In practical applications, the depth of a single microtexture is 5 micrometers ± 0.5 micrometers, the diameter is 20 micrometers ± 2 micrometers, and the center-to-center spacing is 40 micrometers ± 3 micrometers.

[0041] Another sealing structure can be formed inside the end face sealing assembly at the position outside the outer sealing assembly 320. Specifically, a second groove 240 is formed between the bottom side of the sealing platform 210 and the top side of the bottle valve seat 100. The second groove 240 is spaced apart from the side of the first groove 230 away from the center of the inner plug body 220. The end face sealing assembly also includes an inner elastic frame 351 and an outer elastic layer 352 formed on the outer surface of the inner elastic frame 351. The inner elastic frame 351 is arc-shaped with its opening facing the inner plug body 220. The upper and lower sides of the outer elastic layer 352 abut against the sealing platform 210 and the bottle valve seat 100, respectively. The inner elastic frame 351 and the outer elastic layer 352 are respectively arranged around the inner plug body 220. An annular groove is formed on the inner side of the outer elastic layer 352 corresponding to the position of the arc-shaped opening of the inner elastic frame 351. When the leaked gas reaches the outer elastic layer 352, it fills the annular groove and exerts pressure on the inner sidewall of the annular groove. Since the inner elastic frame 351 is an arc shape with its opening facing the inner plug 220, it opens further in the vertical direction along with the outer elastic layer 352 at the position of the annular groove under pressure. At this time, the upper and lower sides of the outer elastic layer 352 abut against the sealing platform 210 and the bottle valve seat 100 respectively, further enhancing the sealing between the two.

[0042] To further improve the sealing effect, the present invention also includes a side sealing assembly, which includes a top pressure ring 410 and an elastic ring 420. An annular sealing groove 221 is provided on the outer side of the inner plug 220. The upper sidewall of the annular sealing groove 221 extends upward in an inclined direction away from the center of the inner plug 220. The elastic ring 420 and the top pressure ring 410 are disposed in the annular sealing groove 221 from top to bottom. The top side of the elastic ring 420 is in close contact with the upper sidewall of the annular sealing groove 221. In practical applications, the side sealing assembly can be located below the connection between the inner plug 220 and the bottle valve seat 100, thereby reducing damage to the connection structure between the inner plug 220 and the bottle valve seat 100. The top pressure ring 410 and the elastic ring 420 form a double seal at the side wall of the inner plug 220 and the inner side of the bottle valve seat 100. When gas leakage occurs, the gas pushes the top pressure ring 410 upward, increasing the pressure of the top pressure ring 410 against the upper side wall of the annular sealing groove 221. Since the upper side wall of the annular sealing groove 221 is inclined and the top side of the elastic ring 420 is in close contact with the upper side wall of the annular sealing groove 221, as the upward pressure of the top pressure ring 410 gradually increases, the elastic ring 420 further fills the gap between the inner plug 220 and the bottle valve seat 100, further improving the overall sealing performance.

[0043] The connection between the sealing platform 210 and the bottle valve seat 100 can also be achieved by threaded connection. The threaded engagement length should be greater than 1 / 3 but not more than 1 / 2 of the length of the sealing surface of the inner wall of the connecting hole of the bottle valve seat 100. This ensures a full connection while enabling quick disassembly and assembly, reducing the disassembly and assembly time by more than half compared to the method where the entire sealing surface is threaded connection.

[0044] To facilitate the fastening of the connecting shell 110 to the outer side of the bottle valve seat 100, in this embodiment, a narrowing section 120 is provided on the outer side of the bottle valve seat 100. The outer radial direction of the narrowing section 120 gradually decreases downward. An outer sealing ring 130 is provided at the bottom of the connecting shell 110, and the outer sealing ring 130 abuts against the outer side of the narrowing section 120. The outer side of the sealing platform 210 is threadedly connected to the inner side of the top of the connecting shell 110. After the sealing platform 210 and the connecting shell 110 are connected to each other, the sealing platform 210 gradually pulls the connecting shell 110 upward, increasing the pressure of the outer sealing ring 130 at the bottom of the connecting shell 110 against the outer side of the narrowing section 120, thereby fastening the connecting shell 110 to the outer side of the bottle valve seat 100.

[0045] In practical applications, the second wedge ring 342, the top pressure ring 410, the elastic ring 420, and the outer sealing ring 130 are all made of graphene or perfluoroether rubber modified with KH-550 silane coupling agent to modify the graphene, with a graphene addition of 4%±0.5% and an elastic modulus ≤1.0GPa at -60℃; the inner elastic frame 351 is made of Inconel 625 alloy, the inner groove of the outer elastic layer 352 has a width of 3.2 mm±0.1 mm and a depth of 1.5 mm±0.1 mm, and the outer annular groove has a width of 0.8 mm±0.05 mm and a depth of 0.5 mm±0.05 mm.

[0046] A method for manufacturing a cryogenic sealing device according to a second aspect of the present invention, for preparing the above-mentioned cryogenic sealing device, includes:

[0047] The first wedge-shaped ring 341 is manufactured by metal additive manufacturing. The overall dimensions of the metal wedge-shaped ring are adapted to the installation space of the valve assembly at the mouth of a 70MPa IV-type hydrogen storage cylinder, with an inner and outer diameter tolerance of ±0.02mm, an axial thickness preferably of 5mm ±0.01mm, and a cone angle of 4° ±0.5°.

[0048] The first inclined surface of the first wedge-shaped ring 341 is laser-processed to form a honeycomb-like microtexture. The depth of each microtexture is 5 μm ± 0.5 μm, the diameter is 20 μm ± 2 μm, and the center-to-center spacing is 40 μm ± 3 μm.

[0049] The first wedge ring 341 is subjected to hot isostatic pressing treatment;

[0050] A zirconium-doped nanocoating is deposited on the first inclined surface of the first wedge-shaped ring 341, covering the interior of the honeycomb microtexture. Magnetron sputtering (300W power, argon flow rate 30 sccm, deposition time 15 min) is used, with a zirconium doping amount of 5% ± 1%, a coating thickness of 70 nm ± 10 nm (the coating thickness at the bottom of the microtexture is not less than 50 nm), a coating-to-metal substrate bonding strength ≥ 35 MPa, a coating edge transition zone length of 1 mm, and a thickness gradient decay to 0, covering the conical surface and the interior of the microtexture. Before coating deposition, plasma cleaning (preferably argon) is required to remove surface oil and activate the metal surface, improving coating adhesion and ensuring surface cleanliness ≤ 5 mg / m². Coating deposition is completed within 1 hour after cleaning to avoid secondary contamination. The coating thickness deviation in the same location is ≤ ± 10 micrometers.

[0051] The first wedge ring 341, after being formed, undergoes laser processing to create a honeycomb microtexture, which increases the contact area with the second wedge ring 342 and enhances sealing stability. Furthermore, it can accommodate minute impurities on the sealing surface, preventing scratches. The processed microtexture improves sealing stability by both increasing the contact area and protecting the sealing surface. Subsequently, hot isostatic pressing (HIP) is used to eliminate internal micropores generated during metal additive manufacturing. A zirconium-doped nanocoating covers the first inclined surface of the first wedge ring 341 and the interior of the microtexture. The zirconium enhances the coating's density, thereby improving its resistance to hydrogen permeation. This effectively improves the structural stability of the first wedge ring 341 and strengthens the tightness of the fit between the first wedge ring 341 and the second wedge ring 342, effectively reducing the safety risks caused by hydrogen leakage in extremely cold regions.

[0052] A method for manufacturing a cryogenic sealing device, comprising:

[0053] In an environment not exceeding -60℃, the sealing plug 200 and the bottle valve seat 100 are connected by gradually increasing torque, and after the previous increase in torque, the temperature is maintained before the next increase in torque is performed.

[0054] Due to the difference in the coefficient of linear expansion between the sealing materials, there is a hysteresis effect in the thermal shrinkage deformation of each component at low temperatures. In order to fully compensate for the thermal shrinkage deformation, and considering that the one-time pre-tightening has caused uneven fit of the sealing surface, sufficient heat preservation is used to fully release the strain generated by each stage of pre-tightening. This can effectively ensure the sealing performance during assembly and prevent leakage caused by insufficient pre-tightening force when used in low-temperature environments.

[0055] Before connecting the sealing plug 200 to the bottle valve seat 100, use Ar gas plasma cleaning for more than 3 minutes with a power of not less than 200W to ensure that the surface cleanliness is ≤5mg / m². After cleaning, the coating deposition should be completed within 1 hour, and the coating thickness deviation in the same area should be ≤±10 micrometers.

[0056] When the sealing plug 200 and the bottle valve seat 100 are connected by gradually increasing torque, the pre-tightening torque is applied in four stages. Specifically, first, the pre-tightening torque is applied at 50% of the design value, and then kept warm for 40 minutes. Next, the pre-tightening torque is applied at 70% of the design value, and then kept warm for 30 minutes. Then, the pre-tightening torque is applied at 90% of the design value, and then kept warm for 20 minutes. Finally, the pre-tightening torque is applied at 100% of the design value. The design value of the pre-tightening torque is determined based on the pressure required by the sealing surface. The torque control accuracy is ±2%, and the stress relaxation rate after 24 hours of pre-tightening is ≤5%.

[0057] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A cryogenic sealing device, characterized in that: include: The bottle valve seat (100) has an outer bottle opening on its top side, and a connecting shell (110) is provided on the outer side of the bottle valve seat (100), the connecting shell (110) protruding upward from the bottle valve seat (100). A sealing plug (200) has a sealing platform (210) formed on its bottom side. An inner plug body (220) is formed on the bottom side of the sealing platform (210). The sealing platform (210) is connected to the inner side of the part of the connecting shell (110) that protrudes upward from the bottle valve seat (100). The inner plug body (220) is inserted into the outer bottle mouth and connected to the inner side of the bottle valve seat (100). A first groove (230) is formed between the bottom side of the sealing platform (210) and the top side of the bottle valve seat (100). An end-face sealing assembly is disposed within the first groove (230). The end-face sealing assembly includes an inner sealing element (310), an expansion portion, and an outer sealing assembly (320) arranged sequentially in a direction away from the inner plug body (220). The outer sealing assembly (320) can press against the expansion portion, causing the expansion portion to press against the sealing platform (210) and the bottle valve seat (100) in a vertical direction. The outer sealing assembly (320) includes a memory alloy wire and a spring connected in series. The shape memory alloy wire and the spring wire abut against the outside of the expansion part. The expansion part includes a first wedge ring (341) abutting against the outside of the inner seal (310) and a second wedge ring (342) abutting against the inside of the outer sealing assembly (320). A first inclined surface is formed on the outside of the first wedge ring (341), and a second inclined surface is formed on the inside of the second wedge ring (342). The first inclined surface abuts against the second inclined surface. The elastic modulus of the first wedge ring (341) is greater than that of the second wedge ring (342). The first inclined surface is provided with a honeycomb micro-texture. A second groove (240) is formed between the bottom side of the sealing platform (210) and the top side of the bottle valve seat (100). The second groove (240) is spaced apart on the side of the first groove (230) away from the center of the inner plug (220). The end face sealing assembly also includes an inner elastic frame (351) and an outer surface formed on the outer surface of the inner elastic frame (351). The elastic layer (352) has an inner elastic frame (351) with an arc shape that opens towards the inner plug (220). The upper and lower sides of the outer elastic layer (352) abut against the sealing platform (210) and the bottle valve seat (100) respectively. The inner elastic frame (351) and the outer elastic layer (352) are respectively arranged around the inner plug (220). An annular groove is provided on the inner side of the outer elastic layer (352) corresponding to the position of the arc-shaped opening of the inner elastic frame (351). A side sealing assembly includes a top pressure ring (410) and an elastic ring (420). An annular sealing groove (221) is provided on the outer side of the inner plug (220). The upper sidewall of the annular sealing groove (221) extends upward in a direction away from the center of the inner plug (220). The elastic ring (420) and the top pressure ring (410) are arranged from top to bottom in the annular sealing groove (221). The top side of the elastic ring (420) is in close contact with the upper sidewall of the annular sealing groove (221).

2. The cryogenic sealing device according to claim 1, characterized in that: A hydrogen content sensor (330) is provided between the sealing platform (210) and the bottle valve seat (100). The hydrogen content sensor (330) is used to detect the hydrogen content leaked between the sealing platform (210) and the bottle valve seat (100). The cryogenic sealing device also includes a cooler configured to cool the shape memory wire according to the detection value of the hydrogen content sensor (330).

3. The cryogenic sealing device according to claim 1, characterized in that: The outer side of the bottle valve seat (100) is provided with a narrowing section (120), the outer radial direction of the narrowing section (120) gradually narrows downward, the bottom of the connecting shell (110) is provided with an outer sealing ring (130), the outer sealing ring (130) abuts against the outer side of the narrowing section (120), and the outer side of the sealing platform (210) is threadedly connected to the inner side of the top of the connecting shell (110).

4. A method for manufacturing a cryogenic sealing device, used to prepare the cryogenic sealing device as described in claim 1, characterized in that: include: The first wedge-shaped ring (341) was formed by metal additive manufacturing. The first inclined surface of the first wedge-shaped ring (341) is processed with a honeycomb microtexture by laser processing; The first wedge ring (341) is subjected to hot isostatic pressing; A zirconium-doped nanocoating is deposited on the first slope of the first wedge ring (341) and covers the interior of the honeycomb microtexture.

5. A method for manufacturing a cryogenic sealing device, used to prepare the cryogenic sealing device as described in any one of claims 1 to 3, characterized in that: include: In an environment not exceeding -60°C, the sealing plug (200) and the bottle valve seat (100) are connected by gradually increasing torque, and the temperature is maintained after the previous increase in torque before the next increase in torque is performed.

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