Two-stage self-sealing anti-micro-leak hydrogen pipeline automatic plug-in break structure and working method thereof

Abstract

The application discloses a two-stage self-sealing anti-micro-leakage hydrogen pipeline automatic plug-in and plug-out structure and a working method thereof. Through the cooperative design of a circular arc sealing pair, a two-stage series driving mechanism, differential spring stiffness and an inert gas purging safety protection cover, the separation process of the mobile end pipeline and the fixed end pipeline is improved from direct overall disconnection to a three-stage state transition process of the male end self-sealing first, the female end self-sealing later and the final complete disconnection, the problems of interface residual liquid retention caused by one-time overall pulling and micro-leakage increase at the moment of disconnection are avoided, the comprehensive requirements of residual liquid backflow, double-end sealing and complete separation are considered, and the repeat positioning accuracy, sealing stability and operation safety in the automatic plug-in and plug-out process of liquid hydrogen are improved.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen energy and cryogenic fluid transportation technology, specifically relating to a two-stage self-sealing anti-leaking liquid hydrogen pipeline automatic plug-in / plug-out switching structure and its working method. Background Technology

[0002] Hydrogen energy, as an important clean secondary energy source, boasts advantages such as high energy density, wide application scenarios, and green and low-carbon operation, showing broad application prospects in transportation, energy storage and peak shaving, industrial raw materials, and distributed energy. Compared to high-pressure gaseous hydrogen storage, liquid hydrogen offers advantages such as high storage density, fast refueling speed, and long endurance, making it more suitable for equipment with large loads, long distances, and long ranges. Therefore, liquid hydrogen-related transportation, refueling, metering, and safety control technologies have become important directions in current hydrogen energy equipment research.

[0003] In liquid hydrogen flow metering and weighing calibration systems, to ensure the accuracy of weighing results, the weighing tank typically needs to be fully decoupled from the external piping system during the weighing stage. This is to avoid the influence of additional pipe volume, mechanical parasitic forces, vibration disturbances, and thermal stress transfer on the weighing results. Existing quick-connect liquid hydrogen on / off connectors usually have a valve stem, return spring, valve body, and cryogenic seal in the male and female ends, respectively. This allows a fluid channel to be established at both ends in the plugged-in state, and a self-sealing effect is achieved by the spring returning the connector to its original position when disconnected. Taking the existing plug-in structure as an example, the springs at the male and female ends use the same or similar equivalent elastic coefficients and preload. This structure can achieve basic quick on / off and self-sealing upon disconnection, but it does not have a differentiated design for the staged disconnection process under liquid hydrogen weighing conditions.

[0004] Because the stiffness and reset characteristics of the springs on both sides of the existing insertion and removal structure are basically the same, the return response of the male and female valve stems during the disengagement process lacks a clear sequence. Under the combined effects of factors such as cryogenic contraction of liquid hydrogen, assembly deviations, changes in frictional resistance, and repeated insertion and removal, the two ends are prone to near-synchronous closure or fluctuations in the closure sequence, making it difficult to stably form a controlled process of "the upper end first self-sealing, the lower end temporarily remaining open to allow residual liquid to flow back, and then the lower end self-sealing again." Especially when the weighing system is separated from the external filling pipeline, if the two ends close near-synchronously or are directly disconnected as a whole, the residual liquid hydrogen in the insertion and removal interface and local cavities is not easy to fully flow back, which can easily lead to stagnation, flash evaporation, and local pressure fluctuations, and may also cause minor leaks, frost, and media loss, which is not conducive to complete physical decoupling during the weighing stage and stable operation under liquid hydrogen conditions.

[0005] Meanwhile, the existing plug-in structure uses a near-trapezoidal compression seal at the main sealing part, resulting in noticeable edges and corners in the sealing contact area. While this type of sealing structure can achieve effective compression at room temperature, stress concentration easily occurs at the sealing edge under conditions of cryogenic contraction of liquid hydrogen, repeated plugging and unplugging, and localized off-center loading. This can lead to uneven distribution of contact pressure and, with prolonged use, may exacerbate localized wear, thereby affecting the sealing surface's fit stability and the consistency of repeated sealing. Therefore, it is necessary to collaboratively improve the existing plug-in structure by addressing the matching of spring parameters on both sides, the staged closing sequence, and the shape of the cryogenic sealing pair to reduce the risk of residual liquid retention and micro-leakage during the disengagement process. Summary of the Invention

[0006] To address the problems of residual liquid backflow, micro-leakage suppression, easy frosting at low-temperature interfaces, and difficulty in achieving stable and complete decoupling during the weighing stage in existing automatic liquid hydrogen pipeline disconnection structures, this invention aims to provide a two-stage self-sealing anti-micro-leakage liquid hydrogen pipeline automatic insertion and removal disconnection structure and its working method. It employs a synergistic design of an arc-shaped sealing pair, a two-stage series drive mechanism, differentiated spring stiffness, and an inert gas purging safety shield. This improves the separation process between the moving and fixed pipelines from a direct overall disconnection to a three-stage state transition process: the male end self-seales first, the female end self-seales later, and finally, complete disconnection. This comprehensively addresses the requirements of residual liquid backflow, double-end sealing, and complete separation, improving the repeatability, sealing stability, and operational safety during the automatic liquid hydrogen insertion and removal process.

[0007] One aspect of the present invention provides a two-stage self-sealing anti-leaking liquid hydrogen pipeline automatic plug-in and disconnection structure, comprising: an upper pipeline moving end, a lower pipeline fixed end, a two-stage series drive mechanism, and an inert gas purging safety protection cover.

[0008] The connecting parts of the upper pipeline moving end and the lower pipeline fixed end are respectively provided with a male end self-sealing structure and a female end self-sealing structure, which are used to cooperate with each other to form a medium channel when plugged in according to the differentiated closing response characteristics, and to complete independent self-sealing in stages after separation.

[0009] The two-stage series drive mechanism is used to form a stable motion constraint with the moving end of the upper pipeline, so that the male end self-sealing structure, along with the moving end of the upper pipeline, always performs insertion, staged self-sealing and reset docking movements relative to the female end self-sealing structure along the same insertion and removal axis.

[0010] The inert gas purging safety cover is used to cover the docking part and continuously introduces inert gas during the separation process to keep the insertion and removal area in a purging state.

[0011] Another aspect of the present invention provides a method for operating the above-mentioned two-stage self-sealing anti-leaking liquid hydrogen pipeline automatic plug-in / plug-out switching structure, comprising the following steps:

[0012] In the connected state, both the primary drive unit and the secondary drive unit are in the initial limit position. The moving end of the upper pipeline is coaxially connected with the fixed end of the lower pipeline along the insertion axis to form a continuous liquid hydrogen flow path.

[0013] In the first stage of separation, the first-stage drive unit moves to the first stage limit position, the second-stage drive unit maintains the initial limit position, the upper pipeline moving end moves along the insertion and extraction axis to generate the first predetermined displacement; the male end spring drives the male end valve stem to return to its original position first and complete the male end self-sealing, the female end valve stem remains open, and the residual liquid hydrogen flows back along the direction of the lower pipeline fixed end.

[0014] In the second stage of separation, the first-stage drive unit maintains the first-stage limit position, the second-stage drive unit moves to the second-stage limit position, the female end spring drives the female end valve stem back to its original position and completes the female end self-sealing, and then the upper pipeline moving end and the lower pipeline fixed end are completely separated.

[0015] During the two-stage separation process, inert gas is continuously introduced into the safety shield to maintain the continuous purging state of the insertion and removal area.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The two-stage series drive of the staged insertion and removal method is adopted, which improves the separation process of the mobile end pipeline and the fixed end pipeline from direct overall disconnection to a three-stage state transition process of self-sealing at the upper end, self-sealing at the lower end, and finally complete disconnection. This avoids the problems of residual liquid retention at the interface and increased micro-leakage at the moment of disconnection caused by one-time overall disconnection, thus taking into account the comprehensive requirements of residual liquid backflow, double-end sealing and complete separation.

[0018] (2) Keep the lower connector connected during the first stage of separation so that the residual liquid at the insertion and removal interface can flow back to the lower weighing tank or storage tank under the action of gravity, which helps to reduce the risk of flash evaporation, frosting and loss of low temperature medium.

[0019] (3) By adopting different stiffness coefficients, preload and installation stroke designs for the male end spring and the female end spring, the upper end joint and the lower end joint can obtain differentiated closing response characteristics, thereby ensuring the sequential stability of the phased action and the self-sealing reliability.

[0020] (4) Replacing the trapezoidal sealing surface structure with a circular arc sealing pair is beneficial to reduce stress concentration at the sealing edge and improve the bonding stability, wear resistance and repeated insertion and removal consistency of the sealing surface under low temperature heat shrinkage conditions.

[0021] (5) Both the first-stage drive unit and the second-stage drive unit use cylinders with axial stroke limit to provide restricted linear displacement in the first and second stages respectively. With the help of the movement direction and stroke limited by the cylinder, the moving end of the upper pipeline always moves along the predetermined insertion and removal axis, ensuring that the male end and the female end maintain coaxial cooperation during insertion, staged separation and reset, thereby improving the alignment stability of repeated insertion and removal and reducing the risk of misaligned insertion, local wear and sealing failure.

[0022] (6) By setting up a helium purging safety protection cover, a local isolation and continuous purging environment can be formed in the insertion and removal area, suppressing the local accumulation of hydrogen and improving the intrinsic safety level of automatic insertion and removal operation under liquid hydrogen conditions. Attached Figure Description

[0023] Figure 1 This is a schematic diagram showing the installation position and main component numbers of a two-stage self-sealing anti-leaking liquid hydrogen pipeline automatic plug-in and disconnection structure in a refueling system according to an embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram of the self-sealing structure of the male and female ends in an embodiment of the present invention;

[0025] Figure 3 yes Figure 1 A schematic diagram of the workstations of each component when the automatic plug-in / plug-out switching structure is in the connected state;

[0026] Figure 4 yes Figure 1 A schematic diagram of the workstations of each component when the automatic plug-in / plug-out switching structure completes the first stage of predetermined small displacement disengagement.

[0027] Figure 5 yes Figure 1 A schematic diagram of the workstations of each component in the automatic plug-in / plug-out switching structure when the second stage of separation is completed;

[0028] Figure 6 yes Figure 2 A partially enlarged structural diagram of the middle circular arc sealing pair;

[0029] Figure 7 yes Figure 1 A schematic diagram of the inert gas purging flow direction. Detailed Implementation

[0030] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are only for explaining the invention and are not intended to limit the scope of protection of the invention. For those skilled in the art, equivalent substitutions or conventional modifications made to the structural form, dimensional parameters, material selection, and control methods without departing from the concept of the invention should all fall within the scope of protection of the invention.

[0031] In this specification, the terms upper, lower, inner, outer, male end, female end, moving end, fixed end, etc., are only used to illustrate the relative positional relationship of the present invention in conjunction with the accompanying drawings, and do not constitute a limitation on the installation direction or usage posture of the present invention.

[0032] like Figure 1 As shown, this application embodiment provides a two-stage self-sealing anti-leaking liquid hydrogen pipeline automatic plug-in / plug-out structure, and adopts a "tank fixed, pipe moving" overall arrangement to connect the on / off structure to the liquid hydrogen weighing and filling system. The main components of the on / off structure include: a primary drive unit 19, an upper pipeline moving end 20, an inert gas purging safety protection cover 21, a lower pipeline fixed end 22, and a secondary drive unit 23.

[0033] The upper pipeline moving end 20 and the lower pipeline fixed end 22 are respectively provided with a male end self-sealing structure and a female end self-sealing structure, which are used to cooperate with each other to form a medium channel when inserted according to the differentiated closing response characteristics, and to complete independent self-sealing in stages after separation.

[0034] The lower pipeline fixed end 22 is connected to the weighing tank or storage tank interface and remains fixed to the tank body during weighing and insertion / removal processes; the upper pipeline moving end 20 is connected to the external conveying pipeline and moves relative to the lower pipeline fixed end 22 along the insertion / removal axis under the staged drive of the first-level drive unit 19 and the second-level drive unit 23, thereby physically separating the weighing tank from the external pipeline during the weighing stage and reducing the impact of the external pipeline load on the weighing process.

[0035] The primary drive unit 19 is used to drive the upper pipeline moving end 20 to complete a first predetermined small displacement during the initial disengagement stage, so that the male end first completes self-sealing while the female end remains open. The secondary drive unit 23 is used to operate after the primary drive unit 19 reaches the first stage limit position, and to continue driving the upper pipeline moving end 20 to complete a second stage displacement along the same insertion / extraction axis, so that the female end subsequently completes self-sealing and the male end and female end are finally completely disengaged.

[0036] Both the primary drive unit 19 and the secondary drive unit 23 employ a cylinder structure with axial stroke limiting. The piston rod of each cylinder performs a restricted linear reciprocating motion along the cylinder body axis, and its corresponding working position is determined by its respective stroke limit. The two are sequentially connected in the lifting drive link of the moving end pipeline, forming a two-stage series drive mechanism. According to the predetermined installation direction, they form a stable motion constraint with the upper pipeline moving end 20, ensuring that the male end always moves along the same insertion and removal axis when the upper pipeline moving end 20 is inserted relative to the female end, performs staged self-sealing, and reset docking. This ensures that the axis of the male end and the axis of the female end always remain coaxial, thereby avoiding eccentric insertion and removal caused by lateral sway or tilt, and improving the centering stability during repeated insertion and removal processes.

[0037] The inert gas purging safety cover 21 is located outside the insertion / removal area of ​​the upper pipeline moving end 20 and the lower pipeline fixed end 22, and is used to cover the docking and separation areas of the two end connectors, and through... Figure 7 The helium inlet, helium outlet, and sealed end shown form a local purging space.

[0038] Furthermore, such as Figure 2 As shown in Figure a, the male end self-sealing structure includes: a quick-connect male end flange 1, a male end outer tube 2, a male end inner tube 3, a male end connecting block 4, a male end spring 5, a male end valve body 6, a male end valve stem 7, a male end PTFE sealing ring 8, a shaft elastic retaining ring 9, and a male end valve body outer sealing ring 10. Figure 2 As shown in Figure b, the female end self-sealing structure includes: a quick-connect female end flange sealing ring 11, a female end flange 12, a female end heat insulation pipe 13, a female end 60-76 connector 14, a female end valve body 15, a female end valve stem 16, a female end spring 17, and a female end connecting block 18.

[0039] The quick-connect structure includes a male flange 1, a male outer tube 2, and a male connector 4, which are sequentially connected vertically from top to bottom. The male inner tube 3 is located inside the male outer tube 2. The male valve body 6 accommodates and constrains the axial movement of the male valve stem 7. The male spring 5 is located between the male connector 4 and the male valve stem 7, and undergoes axial compression and return movements. The male PTFE sealing ring 8 and the shaft elastic retaining ring 9 are adjacently located in the annular groove of the arc-shaped sealing surface at the end of the male valve stem 7, used to cooperate with the arc-shaped sealing surface for self-sealing and to limit the axial movement of the male valve stem 7. The male valve body outer sealing ring 10 is located at the mating part between the front end of the male valve body 6 and the female valve body 15.

[0040] The quick-connect structure female end flange sealing ring 11 is embedded in the upper end face of the female end flange 12 to form a connection seal; the female end flange 12, female end heat insulation pipe 13, female end 60-76 connector 14, female end valve body 15 and female end connecting block 18 are sequentially sleeved from top to bottom in the vertical direction; the female end valve stem 16 is disposed in the female end valve body 15; the female end spring 17 is located between the female end valve stem 16 and the female end connecting block 18, and generates corresponding axial compression or release movement as the female end valve stem 16 opens and returns.

[0041] In particular, although both the male end spring 5 and the female end spring 17 in this embodiment are compression springs, unlike the existing structures that use the same or similar spring stiffness for the male and female ends, this embodiment sets different equivalent elastic coefficients, axial stiffness, and initial preload to make the valve stems on both sides have different return responses.

[0042] In a preferred embodiment, the equivalent elastic coefficient, axial stiffness, and initial preload of the male end spring 5 are all greater than those of the female end spring 17, enabling the male end valve stem 7 to preferentially return to its original position and complete the upper end self-sealing during the first stage of separation. The female end spring 17 employs a relatively smaller axial stiffness and preload, combined with a larger effective return stroke, ensuring that the female end valve stem 16 remains open during the first stage and returns to its original position after further separation in the second stage. This creates a stable operating sequence of "male end sealing first, female end sealing later." When the male and female ends are inserted, the valve stems on both sides overcome the forces of their respective springs under the action of docking, generating axial displacement and opening the flow channel; during separation, the valve stems on both sides return to their original positions in a predetermined order under the action of their respective springs.

[0043] Based on the above structure, the embodiments of this application form three seals: the male end PTFE sealing ring 8 is used to undertake the function of sealing the low temperature medium after the male end valve stem 7 returns to its original position; the male end valve body external sealing ring 10 is used to form a static seal between the male end valve body 6 and the female end valve body 15; and the quick-connect structure female end flange sealing ring 11 is used to form an external connection seal between the quick-connect structure male end flange 1 and the quick-connect structure female end flange 12.

[0044] Preferably, the working surface of the male end PTFE sealing ring 8 is an arc contact surface, and an elastic compensation element can be provided on the inner side to maintain the necessary resilience and uniformity of specific pressure distribution in the low temperature environment of liquid hydrogen.

[0045] In particular, such as Figure 6 As shown, this embodiment updates the existing approximately trapezoidal compression seal to a circular arc sealing pair with a continuously transitional profile. Specifically, both the male valve stem 7 and the female valve stem 16 adopt a circular arc transition structure. This structure has an annular groove at its front end, within which a sealing ring and a shaft elastic retaining ring are placed adjacent to each other. This groove allows for compression deformation along the circular arc transition direction under axial preload, forming a progressive fit seal. This makes the load distribution in the sealing contact area smoother and simultaneously limits the axial movement of the valve stem. Compared to the edge and corner contact of a trapezoidal seal, the circular arc sealing pair helps reduce local stress concentration and local wear caused by repeated insertion and removal, improving the sealing stability and consistency under cryogenic conditions of liquid hydrogen.

[0046] Furthermore, such as Figure 7 As shown, the inert gas purging safety cover 21 is a cover structure that covers the docking area. It has a sealed end at the top, multiple helium inlets arranged circumferentially, and a helium outlet at the bottom. During the separation process, high-purity helium is continuously introduced into the cover, creating a continuous inert gas purging environment in the insertion / removal area as indicated by the arrow in the figure. This dilutes any potentially escaping hydrogen and reduces the entry of oxygen and water vapor from the air into the cryogenic joint area, thereby lowering the risk of localized hydrogen accumulation and frost formation.

[0047] In this embodiment, the male and female ends interact in the plugged state, causing the male valve stem 7 and the female valve stem 16 to overcome the action of the corresponding springs and open the flow channel; when the two ends are gradually separated, the male valve stem 7 and the female valve stem 16 return to their positions in a predetermined order and form their respective self-sealing states.

[0048] Specifically, during the first stage of separation, the male end valve stem 7 is returned to its original position and the upper flow channel is closed, while the female end valve stem 16 remains open, allowing the residual liquid hydrogen at the insertion / removal interface to flow back along the lower flow channel. In the second stage, the separation displacement is further increased, causing the female end valve stem 16 to return to its original position and the lower flow channel to be closed. Subsequently, the moving end 20 of the upper pipeline and the fixed end 22 of the lower pipeline are completely separated.

[0049] With the above structure, the male and female ends form a continuous liquid hydrogen channel when connected. During the separation process, the upper end first self-seales and the lower end later self-seales, and after finally disengaging, they maintain their independent seals, so that the composition, operation state and sealing function of the plug-in structure are consistent with the components shown in the attached figure.

[0050] This application embodiment also provides a working method for the above-mentioned two-stage self-sealing anti-micro-leakage liquid hydrogen pipeline automatic insertion and removal switching structure. The first-stage drive unit 19 and the second-stage drive unit 23 drive the upper pipeline moving end 20 in stages according to the sequence of connection, first-stage separation, second-stage separation and reverse reset. The corresponding working position is determined by the axial stroke limit of each of the two-stage cylinders, so that the upper pipeline moving end 20 moves along the same insertion and removal axis in each stage. During the separation process, helium purging is carried out in conjunction with the inert gas purging safety cover 21.

[0051] Furthermore, the working method includes the following steps:

[0052] like Figure 3 From middle a to Figure 3 As shown in Figure b, in the connected state, both the primary drive unit 19 and the secondary drive unit 23 are in the initial limit position, and the upper pipeline moving end 20 is coaxially inserted with the lower pipeline fixed end 22 along the insertion / extraction axis. At this time, the male valve stem 7 and the female valve stem 16 compress the male spring 5 and the female spring 17 respectively under the docking action, forming a continuous liquid hydrogen flow path between the male inner tube 3, the male valve body 6 and the female valve body 15, and the female 60-76 connector 14. Figure 3 As shown in Figure c, the internal liquid hydrogen is in a connected and flowing state.

[0053] like Figure 4 a and Figure 4As shown in b, in the first-stage separation state, the primary drive unit 19 moves first and reaches the first-stage limit position, while the secondary drive unit 23 maintains the initial limit position. The upper pipeline moving end 20 moves along the insertion / extraction axis to generate the first predetermined displacement. Due to the large axial stiffness and initial preload of the male end spring 5, the male end valve stem 7 returns to its original position first, causing the male end PTFE sealing ring 8 to fit against the arc sealing surface, completing the male end self-sealing. At this time, the female end valve stem 16 has not yet returned to its original position, and the female end flow channel remains open, allowing residual liquid hydrogen in the insertion / extraction interface and local cavity to flow back along the direction of the lower pipeline fixed end 22. In this stage, the axial restricted stroke of the primary drive unit 19 ensures that the upper pipeline moving end 20 does not undergo lateral displacement, and the male and female ends continue to maintain a coaxial relationship.

[0054] like Figure 5 a and Figure 5 As shown in Figure b, in the second-stage separation state, the primary drive unit 19 maintains the first-stage limit position, while the secondary drive unit 23 actuates and reaches the second-stage limit position, causing the upper pipeline moving end 20 to continue moving upward along the same insertion / removal axis. As the second-stage separation displacement increases, the female valve stem 16 returns to its original position under the action of the female spring 17, forming a female end self-sealing. Subsequently, the upper pipeline moving end 20 completely disengages from the lower pipeline fixed end 22, at which point the male and female ends maintain independent seals. The axial restricted stroke of the secondary drive unit 23 ensures that the second-stage separation maintains the same motion axis as the first stage, thereby guaranteeing that the male and female ends remain coaxial before complete disengagement.

[0055] During the first-stage separation and the second-stage separation, high-purity helium is continuously introduced into the inert gas purging safety shield 21 and discharged through the helium outlet to maintain the continuous purging state of the insertion and removal area.

[0056] Based on the above, this embodiment divides the insertion / removal process into three distinct states: In the connected state, both drive units are in their initial limit positions and both the male and female ends are open; in the first-stage separation state, the first-stage drive unit moves to the first-stage limit position, the male end self-seales while the female end remains open to allow residual liquid to flow back; in the second-stage separation state, the second-stage drive unit 23 moves to the second-stage limit position, the female end completes self-sealing, and the upper and lower pipelines are completely separated. The phased limit movements of the two-stage cylinders not only establish a clear action sequence but also ensure that the upper pipeline moving end 20 moves along the same insertion / removal axis throughout the entire process, thereby maintaining the coaxial fit between the male and female ends.

[0057] When liquid hydrogen transport needs to be restored, first, the secondary drive unit 23 is controlled to reverse and reset along the original motion axis, and then the primary drive unit 19 is controlled to reverse and reset along the same motion axis. This ensures that the upper pipeline moving end 20 gradually moves downward along the insertion and removal axis and re-coaxially inserts into the lower pipeline fixed end 22, so that the female valve stem 16 and the male valve stem 7 are back in the open position, thereby restoring the liquid hydrogen flow channel connection. The axial guidance and stroke limit of the two-stage cylinders jointly restrict the movement direction and displacement range of the upper pipeline moving end 20, ensuring that the insertion, separation, and reset processes of the male end relative to the fixed female end remain coaxial.

[0058] The specific displacement and holding time for each stage can be set according to the actual structural stroke, spring parameters, and residual liquid return requirements.

[0059] Under liquid hydrogen conditions, the structural dimensions of the upper pipeline moving end 20 and the lower pipeline fixed end 22, the cylinder stroke and limit position of the first-stage drive unit 19 and the second-stage drive unit 23, the stiffness and preload of the male end spring 5 and the female end spring 17, the clamping amount of the arc sealing pair, and the helium purging flow rate can be engineered and optimized according to the actual needs of the device. For those skilled in the art, without changing the basic concept of the two-stage limit cylinder staged drive, full-process coaxial insertion and removal, staged self-sealing action logic, differentiated spring parameter design, arc sealing pair, and inert gas purging protection described in this invention, corresponding structural adjustments can be made according to different specifications of liquid hydrogen or other cryogenic medium pipelines.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. All equivalent substitutions, conventional deductions, or substitutions using conventional technical means made based on the description and drawings of the present invention should be included within the scope of protection of the present invention.

Claims

1. A two-stage self-sealing, leak-proof, automatic plug-in / plug-out structure for liquid hydrogen pipelines, characterized in that, include: The upper pipeline moving end, the lower pipeline fixed end, the two-stage series drive mechanism, and the inert gas purging safety protection cover; The docking points of the upper pipeline moving end and the lower pipeline fixed end are respectively provided with a male end self-sealing structure and a female end self-sealing structure, which are used to cooperate with each other to form a medium channel when plugged in according to the differentiated closing response characteristics, and to complete independent self-sealing in stages after separation. The two-stage series drive mechanism is used to form a stable motion constraint with the upper pipeline moving end, so that the male end self-sealing structure, along with the upper pipeline moving end, always performs insertion, staged self-sealing and reset docking relative to the female end self-sealing structure along the same insertion axis. The inert gas purging safety cover is used to cover the docking part and continuously introduces inert gas during the separation process to keep the insertion and removal area in a purging state.

2. The two-stage self-sealing anti-leaking liquid hydrogen pipeline automatic plug-in / plug-out switching structure according to claim 1, characterized in that, The two-stage serial drive mechanism includes: The first-stage drive unit is used to drive the moving end of the upper pipeline to complete the first stage of predetermined displacement and disconnection, so that the male end first completes self-sealing while the female end remains open. The secondary drive unit is used to operate after the primary drive unit reaches the first stage limit position, and to continue driving the upper pipeline moving end to complete the second stage displacement along the same insertion and extraction axis, so that the female end subsequently completes self-sealing and the male end and female end are finally completely separated.

3. The two-stage self-sealing anti-leaking liquid hydrogen pipeline automatic plug-in / plug-out switching structure according to claim 2, characterized in that, Both the primary drive unit and the secondary drive unit adopt a cylinder structure with axial stroke limit. The piston rod of each cylinder makes a restricted linear reciprocating motion along the cylinder axis, and the corresponding working position is determined by its respective stroke limit.

4. The two-stage self-sealing anti-leaking liquid hydrogen pipeline automatic plug-in / plug-out switching structure according to claim 1, characterized in that, The male end self-sealing structure includes: a quick-connect male end flange, a male end outer tube, a male end inner tube, a male end connecting block, a male end spring, a male end valve body, and a male end valve stem; The quick-connect structure consists of a male flange, a male outer tube, and a male connector block that are sequentially sleeved vertically from top to bottom. The male inner tube is located inside the male outer tube. The male valve body is used to accommodate and constrain the axial movement of the male valve stem. The male spring is located between the male connector block and the male valve stem and undergoes axial compression and return movements.

5. The two-stage self-sealing anti-leaking liquid hydrogen pipeline automatic plug-in / plug-out switching structure according to claim 4, characterized in that, The female end self-sealing structure includes: a quick-connect female end flange sealing ring, a female end flange, a female end heat insulation pipe, a female end connector, a female end valve body, a female end valve stem, a female end spring, and a female end connecting block; The quick-connect structure female end flange sealing ring is embedded in the upper end face of the female end flange to form a connection seal; the female end flange, female end heat insulation pipe, female end connector, female end valve body and female end connecting block are sequentially sleeved from top to bottom in the vertical direction; the female end valve stem is set in the female end valve body; the female end spring is located between the female end valve stem and the female end connecting block, and generates corresponding axial compression or release movement as the female end valve stem opens and returns.

6. The two-stage self-sealing anti-leaking liquid hydrogen pipeline automatic plug-in / plug-out switching structure according to claim 5, characterized in that, Both the male valve stem and the female valve stem adopt an arc-shaped transition structure. The front end of the structure is provided with an annular groove, in which a sealing ring and a shaft elastic retaining ring are placed adjacent to each other. This is used to compress and deform along the arc transition direction under the action of axial preload, so as to form a progressive fit seal, and at the same time limit the axial movement of the valve stem.

7. The two-stage self-sealing anti-leaking liquid hydrogen pipeline automatic plug-in / plug-out switching structure according to claim 5 or 6, characterized in that, The equivalent elastic coefficient, axial stiffness, and initial preload of the male end spring are all greater than those of the female end spring.

8. The two-stage self-sealing anti-leaking liquid hydrogen pipeline automatic plug-in / plug-out switching structure according to claim 1, characterized in that, The inert gas purging safety cover has a sealed end at the top, a gas outlet at the bottom, and multiple inert gas inlets arranged circumferentially.

9. A method for operating the two-stage self-sealing anti-leaking liquid hydrogen pipeline automatic plug-in / plug-out switching structure as described in any one of claims 1-8, characterized in that, Includes the following steps: In the connected state, both the primary drive unit and the secondary drive unit are in the initial limit position. The moving end of the upper pipeline is coaxially connected with the fixed end of the lower pipeline along the insertion axis to form a continuous liquid hydrogen flow path. In the first stage of separation, the first-stage drive unit moves to the first stage limit position, the second-stage drive unit maintains the initial limit position, the upper pipeline moving end moves along the insertion and extraction axis to generate the first predetermined displacement; the male end spring drives the male end valve stem to return to its original position first and complete the male end self-sealing, the female end valve stem remains open, and the residual liquid hydrogen flows back along the direction of the lower pipeline fixed end. In the second stage of separation, the first-stage drive unit maintains the first-stage limit position, the second-stage drive unit moves to the second-stage limit position, the female end spring drives the female end valve stem back to its original position and completes the female end self-sealing, and then the upper pipeline moving end and the lower pipeline fixed end are completely separated. During the two-stage separation process, inert gas is continuously introduced into the safety shield to maintain the continuous purging state of the insertion and removal area.

10. The working method of the two-stage self-sealing anti-leaking liquid hydrogen pipeline automatic plug-in / plug-out switching structure according to claim 9, characterized in that, Also includes: When liquid hydrogen transport needs to be restored, first control the secondary drive unit to reset in the reverse direction along the original motion axis, then control the primary drive unit to reset in the reverse direction along the same motion axis, so that the moving end of the upper pipeline always moves along the insertion and removal axis until it is re-coaxially inserted with the fixed end of the lower pipeline, and the female valve stem and male valve stem are in the open position again, restoring the liquid hydrogen flow channel connection.

Images