Low-temperature double-sealing structure and assembling method
By combining metal and non-metal seals, the problem of reduced sealing stress at the connection between glass and stainless steel in cryogenic fluid testing is solved, achieving effective sealing and vacuum maintenance under low temperature and high pressure, and is suitable for cryogenic fluid testing equipment.
Patent Information
- Application Number
- CN202511277155.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-09
- Publication Date
- 2025-11-18
AI Technical Summary
In cryogenic fluid testing, the reliable connection between dissimilar materials such as glass and stainless steel is a challenge, especially as the sealing stress decreases in low-temperature environments, causing the sealing structure to fail to maintain an effective seal and making sensor monitoring difficult.
It adopts a combination structure of metal seals and non-metal seals. The metal seals are used to fill the gaps in the sealing surface, while the non-metal seals are used to maintain the seal. The limiting groove design ensures that the seals are stable under high pressure, avoids glass brittleness, and achieves a one-time seal without the need for secondary tightening.
It maintains the sealing performance between the glass and the flange under low temperature and high pressure, realizes the dynamic vacuum of the low temperature device, avoids glass breakage, and ensures no gas leakage. It is suitable for low temperature fluid test devices.
Smart Images
Figure CN120969481A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of cryogenic sealing technology, and in particular to a cryogenic double-sealing structure and assembly method. Background Technology
[0002] Cryogenic propellants such as liquid hydrogen, liquid oxygen, and methane are all cryogenic fluids. Cryogenic fluids have low boiling points, typically below 120K, resulting in a significant temperature difference compared to ambient temperatures. Compared to conventional removable seals, cryogenic testing equipment involves a transient, non-uniform cooling process from ambient temperature (293K) to cryogenic temperatures (below 120K), facing challenges such as mismatched thermal expansion coefficients and decreased sealing stress. In cryogenic fluid testing, the flow and phase states are prone to change, making it extremely difficult to monitor the entire flow field using sensors. An effective method for monitoring the fluid process is to use a viewing window combined with a high-speed camera for observation and measurement. These non-contact measurement methods all require an observation window, raising concerns about the reliable connection between dissimilar materials like glass and stainless steel. Cryogenic experimental chambers typically employ a Dewar structure, with the interlayer evacuated to reduce convective heat transfer from the gaseous medium. Typically, the outer viewing window of a Dewar is sealed with a rubber ring because it is in a normal temperature environment; however, the inner viewing window is in direct contact with the low-temperature fluid, so the sealing structure inside the Dewar cannot be processed after the test begins. Therefore, the sealing structure needs to have the ability to seal once, without the need for secondary tightening. Summary of the Invention
[0003] The purpose of this invention is to provide a low-temperature double-sealing structure and assembly method to solve the problems existing in the prior art and achieve a single-stage sealing without the need for secondary tightening.
[0004] To achieve the above objectives, the present invention provides the following solution:
[0005] The present invention provides a low-temperature double-sealing structure, comprising: a metal seal, a non-metal seal, and a non-metal gasket, wherein the metal seal and the non-metal seal are both located between the inner side of the glass and a first flange, and the non-metal gasket is located between the outer side of the glass and a second flange.
[0006] In some specific embodiments, the metal seal is located inside the non-metal seal; or, the non-metal seal is located inside the metal seal.
[0007] In some specific designs, the first flange has a first placement groove for placing metal seals and a second placement groove for placing non-metal seals.
[0008] In some specific embodiments, the cross-sectional area of the first placement groove is smaller than the cross-sectional area of the metal seal; the cross-section of the first placement groove is V-shaped, and the tip of the cross-section of the first placement groove faces the first flange.
[0009] In some specific designs, the cross-section of the second placement slot is rectangular.
[0010] In some specific designs, the metal seal is an indium wire.
[0011] In some specific designs, the non-metallic seal is a ferrule seal.
[0012] In some specific embodiments, the sealing ring includes a V-shaped spring with the opening of the V-shaped spring facing the cavity inside the glass.
[0013] In some specific designs, the non-metallic gasket is made of polychlorotrifluoroethylene.
[0014] The present invention also provides an assembly method for the aforementioned low-temperature double-sealed structure, comprising:
[0015] Check the non-metallic seals for scratches. Once you are sure that the non-metallic seals are free of scratches, install the non-metallic seals.
[0016] Observe the required length of the metal seal, cut it, and then install the metal seal;
[0017] Install the non-metallic gaskets;
[0018] Rotate the connecting bolts of the first flange and the second flange to ensure that the metal seal extends evenly.
[0019] The present invention achieves the following technical effects compared to the prior art:
[0020] The non-metallic seal of this invention has the characteristic of maintaining a seal under high pressure, while the metallic seal has the ability to fill gaps in the sealing surface and compensate for the machining accuracy of the sealing surface. The metallic and non-metallic seals can compensate for each other to achieve a sealing effect under low temperature and high pressure. This invention can maintain the primary sealing performance between the glass and the first flange under low temperature and high pressure, and realize the maintenance of the dynamic vacuum degree of the vacuum jacket in the low temperature device. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0022] Figure 1 This is a cross-sectional view of a low-temperature double-sealed structure in some embodiments of the present invention;
[0023] Figure 2This is a schematic diagram of the first placement slot in some embodiments of the present invention;
[0024] Figure 3 This is a schematic diagram of the second placement slot in some embodiments of the present invention;
[0025] In the diagram: 100 - Low-temperature double-sealed structure, 1 - Glass, 2 - First flange, 3 - First placement groove, 4 - Second placement groove, 5 - Non-metallic gasket, 6 - Second flange. Detailed Implementation
[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0027] The purpose of this invention is to provide a low-temperature double-sealing structure and assembly method to solve the problems existing in the prior art and achieve a single-stage sealing without the need for secondary tightening.
[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0029] Example 1
[0030] like Figures 1 to 3 As shown, this embodiment provides a low-temperature double-sealing structure 100, including: a metal seal, a non-metal seal, and a non-metal gasket 5. Both the metal and non-metal seals are located between the inner side of the glass 1 and the first flange 2, while the non-metal gasket 5 is located between the outer side of the glass 1 and the second flange 6. In this embodiment, the non-metal seal has the characteristic of maintaining a seal under high pressure, while the metal seal has the ability to fill gaps in the sealing surface and compensate for the machining accuracy of the sealing surface. The metal and non-metal seals can compensate for each other to achieve a sealing effect under low temperature and high pressure. This embodiment can maintain the primary sealing performance between the glass 1 and the first flange 2 under low temperature and high pressure, thus maintaining the dynamic vacuum degree of the vacuum jacket in the low-temperature device.
[0031] In some embodiments, the metal seal is located inside the non-metal seal; or, the non-metal seal is located inside the metal seal.
[0032] In some specific embodiments, the first flange 2 has a first placement groove 3 for placing a metal seal and a second placement groove 4 for placing a non-metal seal. The first placement groove 3 is used to limit the metal seal, and the second placement groove 4 is used to limit the non-metal seal. The metal seal is placed in the first placement groove 3 and the non-metal seal is placed in the second placement groove 4, which can achieve a line seal. After shrinkage, the glass 1 does not become brittle and the sealing stress remains stable under high pressure.
[0033] In some specific embodiments, the cross-sectional area of the first placement groove 3 is smaller than that of the metal seal; the cross-section of the first placement groove 3 is V-shaped, and the tip of the cross-section of the first placement groove 3 faces the first flange 2. The dimensional relationship between the cross-section of the first placement groove 3 and the metal seal ensures that the metal seal can fit snugly against the glass 1, fill the gaps in the sealing surface, compensate for the machining accuracy of the sealing surface, and ensure that gas does not leak. The shape and opening orientation of the first placement groove 3 make it easy for the metal seal to fill the first placement groove 3 under the pressure of the glass 1, the first flange 2, and the second flange 6 when the metal seal is placed in the first placement groove 3.
[0034] In some specific embodiments, the dimensions of the second placement groove 4 are designed without considering the gap between the sealing surfaces after assembly and tightening. The cross-section of the second placement groove 4 is rectangular, and the interior of the second placement groove 4 needs to maintain a certain roughness. The design of the dimensions of the second placement groove 4 only needs to consider that the non-metallic seal can maintain its elasticity after the glass 1 is pressed against the first flange 2, and has the characteristic of maintaining a seal under high pressure, so as to avoid excessive stress causing the glass 1 to break.
[0035] In some specific embodiments, the metal seal is an indium wire, gold wire, lead wire, pure aluminum gasket, oxygen-free copper gasket, or metal hollow O-ring.
[0036] In some specific embodiments, the non-metallic seal is a plug seal ring.
[0037] In some embodiments, the sealing ring includes a V-shaped spring (with a V-shaped opening) with the opening of the V-shaped spring facing the cavity inside the glass 1.
[0038] In some specific embodiments, the non-metallic gasket 5 is made of polychlorotrifluoroethylene.
[0039] In some specific embodiments, both the first flange 2 and the second flange 6 are made of stainless steel.
[0040] The non-metallic seal in this embodiment uses a plug seal ring, which maintains its resilience after the glass 1 is pressed against the stainless steel (first flange 2, second flange 6), exhibiting the characteristic of maintaining a seal under high pressure and preventing the glass 1 from shattering due to excessive stress. The metallic seal in this embodiment uses indium wire, which can fill the gaps in the sealing surface, compensate for the machining accuracy of the sealing surface, and ensure that the gas does not leak. This embodiment, through the combined use of metallic and non-metallic seals, can be repeatedly used between room temperature and low temperature conditions. At room temperature, it can be tightened once without the need for re-tightening after low-temperature shrinkage. During room temperature, low-temperature steady-state conditions, and pre-cooling transient processes, the low-temperature double-seal structure 100 of this embodiment maintains a low leakage rate and maintains the dynamic high vacuum of the interlayer without leakage.
[0041] Application examples
[0042] The cryogenic glass 1 is held between a pair of stainless steel flanges (first flange 2 and second flange 6). The diameters of the first flange 2 and second flange 6 are 148 mm and the thickness is 22 mm. The glass 1 is cryogenic high borosilicate glass with a thickness of 25 mm. The first placement groove 3 is a 60-degree (α, β) V-groove with a width W of 1.5 mm. The second placement groove 4 has a rectangular cross-section, a depth H of 4.75 mm, and a surface roughness of Ra0.2. Eight M12 connecting bolts are used to pre-tighten the sealing structure. To prevent direct hard contact between the glass 1 and the stainless steel, which could easily cause cracking, a non-metallic gasket 5 made of PCTFE is used between the outer side of the glass 1 and the second flange 6. The non-metallic seal includes a V-shaped spring; that is, the cross-section of the spring energy storage coil inside the non-metallic seal is V-shaped, with the opening facing the high-pressure interior (i.e., the cavity facing the inside of the glass 1).
[0043] Leakage rate tests were conducted at room temperature and low temperature for two operating conditions: non-metallic seals only and non-metallic seals + metallic seals. Helium detection was performed using the container method. After filling with liquid nitrogen until the sealing structure was completely cooled, the pressure was increased to 3MPa.
[0044] Table 1 Leakage rate results at normal and low temperatures
[0045] Operating conditions Non-metallic seals Non-metallic seals + metallic seals <![CDATA[3 MPa normal temperature leak rate (unit: Pa·m 3 / s)]]> <![CDATA[1*10 -5 ]]> <![CDATA[9.5*10 -11 ]]> <![CDATA[3MPa low temperature leakage rate (unit: Pa·m 3 / s)]]> Leak detector alarm <![CDATA[1*10 -10 ]]>
[0046] As shown in Table 1, when using non-metallic seals, the leakage rate at room temperature under 3MPa is 1*10-1. -5 However, by combining non-metallic and metallic seals, the leakage rate at room temperature under 3MPa is 9.5*10. -11 When using non-metallic seals, detecting low-temperature leakage at 3MPa will trigger an alarm on the leak detector. However, when using a combination of non-metallic and metallic seals, the low-temperature leakage rate at 3MPa is 1*10. -10Therefore, it can be seen that the low-temperature double-sealing structure 100 of this embodiment can achieve effective sealing at both room temperature and low temperature.
[0047] Example 2
[0048] This embodiment provides an assembly method for the low-temperature double-sealed structure 100 of Embodiment 1, including:
[0049] Observe whether there are scratches on the non-metallic seal. After ensuring that there are no scratches on the non-metallic seal, place the non-metallic seal in the second placement groove 4.
[0050] Observe the required length of the metal seal, cut both ends of the metal seal at a 45-degree angle (i.e., the end faces of both ends of the metal seal are at a 45-degree angle to the axis of the metal seal), and then place the metal seal in the first placement groove 3.
[0051] Install the non-metallic gasket 5 between the outside of the glass 1 and the second flange 6;
[0052] Turn the entire structure upside down, rotate the connecting bolts of the first flange 2 and the second flange 6, apply pressure evenly to each connecting bolt to ensure that the metal seal is stretched evenly, and tighten each connecting bolt with a torque wrench to apply appropriate torque.
[0053] The non-metallic seal in this embodiment uses a plug seal ring, which maintains its resilience after the glass 1 is pressed against the stainless steel (first flange 2, second flange 6), exhibiting the characteristic of maintaining a seal under high pressure and preventing the glass 1 from shattering due to excessive stress. The metallic seal in this embodiment uses indium wire, which can fill the gaps in the sealing surface, compensate for the machining accuracy of the sealing surface, and ensure that the gas does not leak. This embodiment, through the combined use of metallic and non-metallic seals, can be repeatedly used between room temperature and low temperature conditions. At room temperature, it can be tightened once without the need for re-tightening after low-temperature shrinkage. During room temperature, low-temperature steady-state conditions, and pre-cooling transient processes, the low-temperature double-seal structure 100 of this embodiment maintains a low leakage rate and maintains the dynamic high vacuum of the interlayer without leakage.
[0054] In the description of this invention, it should be understood that the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, 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, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.
[0055] In the description of this invention, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0056] If this invention discloses or relates to components or structural parts that are fixedly connected to each other, then, unless otherwise stated, a fixed connection can be understood as: a fixed connection that can be detached (e.g., using bolts or screws), or a fixed connection that cannot be detached (e.g., riveting, welding). Of course, a fixed connection can also be replaced by an integral structure (e.g., manufactured in one piece using a casting process) (except where it is obviously impossible to use an integral molding process).
[0057] In addition, unless otherwise stated, the terms used in any of the technical solutions disclosed in this invention to indicate positional relationships or shapes include states or shapes that are similar to, close to, or approximate with those states or shapes.
[0058] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured by a one-piece molding process.
[0059] It should be noted that the structures, proportions, sizes, etc., depicted in the accompanying drawings of this specification are only used to complement the content disclosed in the specification, so as to enable those skilled in the art to understand and read them, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.
[0060] It should also be noted that in the embodiments of this application, the same reference numerals are used to denote the same component or the same part.
[0061] Any adaptive changes made according to actual needs are within the scope of protection of this invention.
[0062] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.
Claims
1. A cryogenic dual seal structure, characterized by: The application relates to a glass sealing structure, which comprises the following parts: a metal sealing piece and a nonmetal sealing piece, both of which are located between the inner side of glass and a first flange; and a nonmetal gasket which is located between the outer side of glass and a second flange.
2. The cryogenic dual seal structure of claim 1, wherein: The metal sealing piece is located inside the nonmetal sealing piece, or the nonmetal sealing piece is located inside the metal sealing piece.
3. The cryogenic dual seal structure of claim 1, wherein: The first flange is provided with a first placing groove for placing the metal sealing piece and a second placing groove for placing the nonmetal sealing piece.
4. The cryogenic dual seal structure of claim 3, wherein: The cross-sectional area of the first placing groove is smaller than that of the metal sealing piece; the cross section of the first placing groove is V-shaped, and the tip of the cross section of the first placing groove faces the first flange.
5. The cryogenic dual seal structure of claim 3, wherein: The cross section of the second placing groove is rectangular.
6. The cryogenic dual seal structure of claim 1, wherein: The metal sealing piece is an indium wire.
7. The cryogenic dual seal structure of claim 1, wherein: The nonmetal sealing piece is a generic seal ring.
8. The cryogenic dual seal structure of claim 7, wherein: The generic seal ring comprises a V-shaped spring, and the opening of the V-shaped spring faces the cavity on the inner side of glass.
9. The cryogenic dual seal structure of claim 1, wherein: The nonmetal gasket is made of polytrifluorochloroethylene.
10. A method of assembling a cryogenic dual seal structure according to any one of claims 1-9, characterized in that: The application also relates to a glass sealing method, which comprises the following steps: observing whether the nonmetal sealing piece has scratches, and installing the nonmetal sealing piece after ensuring that the nonmetal sealing piece has no scratches; observing the required length of the metal sealing piece, cutting the metal sealing piece, and then installing the metal sealing piece; installing the nonmetal gasket; turning the connecting screw of the first flange and the second flange to ensure that the metal sealing piece is uniformly stretched.