Metal sealing angle valve for high-frequency opening and closing in ultrahigh vacuum environment

Abstract

The invention relates to the technical field of angle valves, in particular to a high-frequency opening and closing metal sealing angle valve for an ultrahigh vacuum environment, which is suitable for connecting or disconnecting an ultrahigh vacuum cavity with the external environment to realize dynamic sealing of the ultrahigh vacuum cavity and comprises an angle valve body and a valve rod. The sealing structure between the angle valve body and the valve rod comprises a dynamic sealing assembly and a sealing assembly, wherein a liftable knife edge structure and a liquid metal sealing medium form a first-stage fluid seal; and the static sealing assembly is arranged on the periphery of the dynamic sealing assembly and comprises an elastic sealing assembly and a sealing face arranged on the angle valve body, and when the dynamic sealing assembly is started, the static sealing assembly is synchronously triggered to conduct secondary mechanical sealing. The liquid metal is contained on the angle valve body, and opening and closing of the angle valve body are achieved by inserting the knife edge structure into or pulling the knife edge structure out of the liquid metal. According to the metal sealing angle valve for the high-frequency switch in the ultrahigh vacuum environment, the requirement for high-frequency switch can be met, and the service life is long.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vacuum angle valve, in particular to a metal seal angle valve for high-frequency switching in ultra-high vacuum environment. BACKGROUND

[0002] Ultra-high vacuum refers to a vacuum environment with a pressure lower than 1.33×10 -6 ~ 1.33×10 -9 Pascals, in which the molecular density is only one part in a trillion of standard atmospheric pressure, and the mean free path of molecules can reach tens of kilometers. In this environment, gas molecules mainly collide with the container wall rather than with each other, resulting in high cleanliness. The time for sample surface contamination is extended from 3 seconds in conventional high vacuum to several hours, providing ideal conditions for precision analysis in surface science, semiconductor manufacturing, and other fields.

[0003] Under ultra-high vacuum conditions, the number of gas molecules is reduced, so the parameters and measurement results of the instrument are more stable and reliable. For example, an electron microscope is an instrument that uses an electron beam instead of visible light to form an image. Under normal pressure, air molecules will collide with the electron beam, causing scattering phenomena and reducing resolution. In an ultra-high vacuum environment, air molecules are effectively excluded, and the electron beam can accurately scan the sample, thereby improving the resolution and imaging quality of the electron microscope. For another example, a spectrometer is an instrument that uses the properties of light to analyze and characterize matter. Under normal pressure, gas molecules will absorb and scatter light signals, interfering with the measurement of spectral lines. Under ultra-high vacuum conditions, the number of gas molecules is greatly reduced, making the propagation path of light signals more stable and controllable, thereby improving the precision and sensitivity of the spectrometer.

[0004] However, obtaining ultra-high vacuum not only requires extremely strict requirements for the material, precision machining and surface treatment process of the cavity, but also has very high requirements for the vacuum obtaining equipment. However, there is another crucial link that affects the obtaining of ultra-high vacuum environment, which is the sealing of the entire ultra-high vacuum cavity. Therefore, in the design process of the ultra-high vacuum system, the sealing design and device selection at the interface between the ultra-high vacuum cavity and each connecting device are very critical. The sealing method at these interfaces usually adopts metal sealing, that is, the hard valve plate and sealing surface are used to extrude the soft metal to cause deformation. The valve plate and sealing surface usually have regular and symmetrical annular protrusions, i.e. knife edges. During the extrusion of the soft metal, the knife edges on both sides are embedded into the surface of the soft metal. In this way, the soft metal not only realizes the compression of the valve plate and the sealing surface to become a sealed metal whole, but also realizes the purpose of filling the sharp defects of the knife edges due to its soft texture. The metal sealing material is usually selected from soft metals such as copper, silver and aluminum. However, metal sealing is usually suitable for static sealing because the deformation of soft metal extrusion is irreversible, i.e. once installed and extruded to achieve sealing, it cannot be opened again. If it is opened again and then sealed, a new soft metal sealing gasket needs to be replaced. Therefore, in many application scenarios, such as sealing surfaces that need to be frequently opened and closed, it is very difficult to seal with soft metal. The vacuum angle valve, which is a component used in vacuum systems, is shown below. Figure 1

[0005] Most existing vacuum angle valves use O-shaped rubber ring sealing. This sealing method is suitable for low vacuum and high vacuum, but not for ultra-high vacuum and higher vacuum. Because the O-shaped rubber ring sealing has disadvantages, it is not tight and may have slight leakage, making it difficult for the vacuum system to reach ultra-high vacuum. In addition, the outgassing amount (i.e. the amount of gas released by a unit volume of material in a certain vacuum degree) of the O-shaped rubber ring is too high in an ultra-high vacuum environment, forming a gas source and making it difficult for the system to reach ultra-high vacuum.

[0006] ​In the prior art, there is also a vacuum angle valve, which is pressed on the conical sealing surface of the valve body by a stainless steel sheet plated with silver on the outer surface to perform extrusion sealing; the silver on the outer surface of the stainless steel sheet is extruded between the stainless steel sheet and the conical sealing surface to make the silver deform and realize sealing; the stainless steel sheet can return to the original state after being opened, so that the stainless steel sheet is separated from the conical sealing surface, and the stainless steel sheet can be used multiple times; however, due to the problem of stainless steel stress fatigue, high-frequency switching cannot be realized; this sealing method also has disadvantages, first, the frictional contact between silver and the sealing surface will cause consumption of silver, and silver peeling will occur; silver peeling will produce silver particles, causing environmental pollution; in addition, the contact between the stainless steel sheet and the conical sealing surface is fragile, and if dust falls during use, the valve will fail. How to provide an angle valve for an ultra-high vacuum environment is a problem to be solved. SUMMARY

[0007] The purpose of the present application is to provide a metal-sealed angle valve for high-frequency switching in an ultra-high vacuum environment to solve the problem that the vacuum angle valve in the prior art cannot be applied in an ultra-high vacuum environment due to poor sealing or easy failure.

[0008] The technical solution of the present application is: a metal-sealed angle valve for high-frequency switching in an ultra-high vacuum environment, which is suitable for connecting or disconnecting an ultra-high vacuum cavity with the external environment to realize dynamic sealing of the ultra-high vacuum cavity, comprising an angle valve body and a valve stem, and the sealing structure between the angle valve body and the valve stem comprises: A dynamic sealing assembly composed of a liftable knife edge structure and a liquid metal sealing medium for primary fluid sealing; A static sealing assembly arranged on the periphery of the dynamic sealing assembly, comprising an elastic sealing assembly and a sealing surface arranged on the angle valve body, which is triggered synchronously with the dynamic sealing assembly to perform secondary mechanical sealing when the dynamic sealing assembly is activated.

[0009] Preferably, the liquid metal is contained in the angle valve body, and the opening and closing of the angle valve body are realized by inserting or removing the liquid metal through the knife edge structure; When the knife edge structure is inserted into the liquid metal for primary sealing, the elastic sealing assembly is in close contact with the sealing surface to achieve airtight isolation between the ultra-high vacuum cavity and the external environment, thereby realizing secondary sealing; when the knife edge structure is removed from the liquid metal, the elastic sealing assembly is separated from the sealing surface.

[0010] Preferably, the angle valve body comprises a bottom channel connected to the ultra-high vacuum cavity, and a first annular groove is arranged around the outlet in the valve to contain the liquid metal; The knife edge structure is annular and has a sharp lower end to pierce the oxide layer on the surface of the liquid metal.

[0011] Preferably, the knife edge structure is arranged on the bottom end surface of the valve stem, and the diameter of the lower end of the valve stem is greater than the diameter of the outlet of the bottom channel.

[0012] Preferably, the angle valve body comprises a sealingly fixed upper cover body and a lower shell with a flat top, the bottom channel is arranged on the lower shell, and the first annular groove is arranged in the top surface of the lower shell.

[0013] Preferably, the elastic sealing assembly is a sealing ring, and the sealing ring is arranged on the bottom end surface of the valve stem.

[0014] Preferably, the bottom end surface of the valve stem is provided with a second annular groove arranged around the outer periphery of the knife edge structure, and the sealing ring is arranged in the second annular groove.

[0015] Preferably, the vertical section of the first annular groove is square.

[0016] Preferably, the lower end of the lower shell is sealingly communicated with a lower flange.

[0017] Preferably, the side edge of the upper cover body is sealingly communicated with a side flange.

[0018] Compared with the prior art, the present application has the following advantages: (1) The metal sealing angle valve for high-frequency switching in an ultra-high vacuum environment comprises a dynamic sealing assembly and a static sealing assembly, realizes primary fluid sealing and secondary mechanical sealing, and the sealing ring can avoid the pressure difference between the liquid metal on both sides and the outside environment in the ultra-high vacuum environment, avoid the liquid metal being pushed to the vacuum side by atmospheric pressure, and cause sealing failure. At the same time, the sealing of the knife edge structure and the liquid metal can prevent the sealing ring from releasing trace gas when it contacts the ultra-high vacuum environment, and avoid the problem that the sealing ring in the prior art affects the vacuum degree in the ultra-high vacuum environment.

[0019] (2) The metal sealing angle valve for high-frequency switching in an ultra-high vacuum environment adopts liquid metal for sealing, and the liquid metal can be deformed to achieve effective sealing when it is in a sealing state (i.e. when the knife edge structure is pressed down), and returns to its original state when it is connected and opened (i.e. when the knife edge structure is lifted up). During the switching process of the above sealing and opening, the liquid metal is not damaged and no heat is generated. At the same time, the liquid metal has high resistance to dust and can meet the requirements of high-frequency switching, and has a long service life.

[0020] (3) The metal sealing angle valve for high-frequency switching in an ultra-high vacuum environment has a sharp lower end of the knife edge structure, which has a better sealing effect than a plate-shaped structure. BRIEF DESCRIPTION OF DRAWINGS

[0021] The application will be further described below in conjunction with the drawings and embodiments: Figure 1 A structure diagram of a vacuum angle valve in the prior art; Figure 2 A structure diagram of a metal-sealed angle valve for high-frequency switching in an ultrahigh vacuum environment; Figure 3 A top view of Figure 2 ; Figure 4 A structure diagram of Figure 3 A-A section; Figure 5 An enlarged structure diagram of Figure 4 A section.

[0022] Wherein: 1, knife edge structure, 2, side flange, 3, liquid metal, 4, sealing ring, 5, valve rod, 6, bottom passage, 7, first annular groove, 8, upper cover body, 9, lower shell, 10, lower flange. DETAILED DESCRIPTION

[0023] The content of the application will be further described below in conjunction with specific embodiments: In the description of the application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0024] As shown in Figures 2-5 , a metal-sealed angle valve for high-frequency switching in an ultrahigh vacuum environment is suitable for connecting or disconnecting an ultrahigh vacuum cavity with the external environment, realizing dynamic sealing of the ultrahigh vacuum cavity, and comprising an angle valve body (upper cover body 8, lower shell 9) and a valve rod 5. The opening and closing of the angle valve are realized by the movement of the valve rod 5 in the angle valve body. Then, in the closed state of the angle valve, the sealing performance at the closed part needs to be ensured to meet the application requirements of the ultrahigh vacuum environment.

[0025] The application designs sealing structures distributed on the angle valve body and the valve rod 5 to meet the requirements of the ultrahigh vacuum environment, mainly including dynamic sealing assemblies and static sealing assemblies.

[0026] The dynamic sealing assembly is composed of the liftable knife edge structure 1 and the liquid metal 3 sealing medium, and the static sealing assembly is arranged at the periphery of the dynamic sealing assembly and includes an elastic sealing assembly and a sealing surface arranged on the angle valve body, and when the dynamic sealing assembly is started, the static sealing assembly is triggered synchronously to perform secondary mechanical sealing.

[0027] Specifically, the liquid metal 3 is contained in the angle valve body, and the opening and closing of the angle valve body are realized by inserting or separating the knife edge structure 1 into or from the liquid metal 3; when the knife edge structure 1 is inserted into the liquid metal 3 to perform primary sealing, the elastic sealing assembly is attached to the sealing surface to perform airtight isolation between the ultrahigh vacuum cavity and the external environment, thereby realizing secondary sealing; when the knife edge structure 1 is separated from the liquid metal 3, the elastic sealing assembly is separated from the sealing surface. The elastic sealing assembly is a sealing ring 4, which is installed at the bottom end face of a valve rod 5.

[0028] In this embodiment, the pressure difference between the ultrahigh vacuum cavity and the external environment is extremely large, and the liquid metal 3 has fluidity. When it is used as primary sealing, its sealing effect depends on the filling state of the interface gap with the knife edge structure 1, and the huge pressure difference may destroy this balance. If only primary sealing is relied on, the liquid metal 3 on both sides will directly bear the full pressure difference, and may be pushed to the vacuum side by the atmospheric pressure. The liquid metal 3 in the first annular groove 7 may flow out of the groove, resulting in sealing failure. The sealing position formed by the sealing ring 4 and the sealing surface is located on the “atmosphere side” of the liquid metal 3 sealing position (i.e., closer to the external environment), which is equivalent to adding a barrier between the atmosphere and the liquid metal 3. The external atmospheric pressure first acts on the sealing ring 4, which is blocked by the secondary sealing. At this time, the pressure difference on both sides of the liquid metal 3 is small, and this small pressure difference is not enough to push the liquid metal 3 to maintain close contact with the knife edge structure 1 (relying on capillary action and surface tension to fill the gap), thereby ensuring the long-term effectiveness of primary sealing. At the same time, due to the arrangement of the sealing ring 4, a smaller amount of liquid metal 3 in the first annular groove 7 can complete primary sealing. It is worth noting that based on the distribution of primary sealing and secondary sealing in this application, the liquid level of the liquid metal 3 is not required, only the knife edge structure 1 can be smoothly inserted into the liquid metal 3. Without the requirement of high liquid level of the liquid metal 3, a too deep first annular groove 7 needs to be opened on the angle valve body, and at this time, the strength of the original angle valve body can no longer meet the use requirements.

[0029] In addition, in an ultra-high vacuum environment, the sealing ring 4 in contact with the vacuum releases a small amount of gas (such as adsorbed moisture, air, and self-volatiles, i.e., "gas release effect"), which is a key factor affecting the vacuum degree. If the sealing ring 4 is directly exposed to the vacuum side, the gas released by the sealing ring 4 will directly enter the ultra-high vacuum chamber, causing the vacuum degree to drop. The secondary sealing in the present application solves this problem through "path isolation". The sealing ring 4 is located outside the knife edge structure 1 and the liquid metal 3 seal, and is completely isolated from the ultra-high vacuum chamber. When the angular valve body is in a sealed state, the sealing ring 4 has no effect on the vacuum degree of the ultra-high vacuum chamber. Further, in the case of achieving ultra-high cleanliness, the sealing performance is also satisfied.

[0030] In the present application, the liquid metal 3 is used for sealing. The liquid metal 3 can be deformed to achieve effective sealing when it is in a sealed state (i.e., when the knife edge structure 1 is pressed down). When the liquid metal 3 returns to its original state when the knife edge structure 1 is lifted, the liquid metal 3 is in a connected and open state. During the switching process of the above sealing and opening, the liquid metal 3 is not damaged and no heat is generated. At the same time, the liquid metal 3 has a high resistance to dust and can meet the requirements of high-frequency switching, and has a relatively long service life.

[0031] The corner valve body includes a bottom channel 6 in communication with the ultra-high vacuum cavity, and a first annular groove 7 is arranged at the outlet of the valve body to hold the liquid metal 3. The knife edge structure 1 is annular and the lower end is sharp to pierce the oxide layer on the surface of the liquid metal 3. In this embodiment, the lower end of the knife edge structure 1 is sharp, which has better sealing effect than the plate structure. The specific reason is that the liquid metal 3 will quickly form a very thin (nanometer level) oxide layer in the air. The oxide layer is brittle but has a certain strength, which can "support" the shape of the liquid metal 3 (avoid unconstrained flow), but can be pierced, extruded or reshaped under external force. When the plate structure is inserted, its flat surface has a large contact area with the liquid metal 3, and the oxide layer is uniformly and dispersedly pressed, which is difficult to be completely destroyed. The complete oxide layer may be attached to the surface of the plate structure like a "film", which prevents the liquid metal 3 from fully filling the interface between the plate structure and the liquid metal 3, forming a small gap that can leak gas under ultra-high vacuum, which may cause sealing failure. The sharp knife edge structure 1 in this embodiment can pierce or tear the oxide layer on the surface of the liquid metal 3, exposing the underlying unoxidized liquid metal 3 body. The broken oxide layer fragments will be extruded by the pressure on both sides of the knife edge structure 1, "flow and redistribute" along the edge surface, and finally form a dense oxide layer at the interface between the knife edge structure 1 and the liquid metal 3, which not only fixes the position by using the strength of the oxide layer, but also fills the small gap by the fluidity of the liquid metal 3 body, eliminating the gap between the knife edge structure 1 and the liquid metal 3. In addition, the capillary action of the liquid metal 3 is the key to filling the interface gap. The interface gap of the plate structure has the characteristics of "wide and dispersed", which significantly weakens the capillary action. After the knife edge structure 1 pierces the oxide layer, the gap formed with the liquid metal 3 body is usually nanoscale, and the liquid metal 3 will be strongly "sucked" into the gap, achieving spontaneous and complete filling, significantly enhancing the filling ability of the capillary action to the gap. The enhanced capillary action of the knife edge structure 1 not only fills the initial gap, but also "self-repairs" through the spontaneous flow of the liquid metal 3 when the small gap fluctuates due to vibration and temperature change during the sealing process, maintaining long-term sealing stability.

[0032] The knife edge structure 1 is arranged on the bottom end surface of the valve stem 5, and the diameter of the lower end of the valve stem 5 is greater than the diameter of the outlet of the bottom passage 6 in the valve. The valve body comprises a sealingly fixed upper cover 8 and a lower shell 9 with a flat top, the bottom passage 6 is arranged on the lower shell 9, and the first annular groove 7 is arranged on the top surface of the lower shell 9. The bottom end surface of the valve stem 5 is provided with a second annular groove arranged around the outer periphery of the knife edge structure 1, and the sealing ring 4 is arranged in the second annular groove. The vertical section of the first annular groove 7 is square, of course, the vertical section of the first annular groove 7 is not limited to this structure, and can also be V-shaped, swallow-tailed, U-shaped, etc. The lower end of the lower shell 9 is sealingly connected with the lower flange 10, and the side of the upper cover 8 is sealingly connected with the side flange 2.

[0033] In summary, the dynamic sealing assembly and the static sealing assembly are arranged between the valve body and the valve stem 5 in the application, which realizes primary fluid sealing and secondary mechanical sealing, has sufficient service life under the premise of ensuring ultra-high sealing performance, and further overcomes the problem of easy failure, and has a significant breakthrough in application in ultra-high vacuum environment.

[0034] The above examples are only for illustrating the technical concept and characteristics of the application, and the purpose is to enable those skilled in the art to understand the content of the application and implement it, and cannot limit the protection scope of the application. For those skilled in the art, it is obvious that the application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the application, therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the application is defined by the appended claims rather than the above description, therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the application.

Claims

1. A metal-sealed angle valve for high-frequency switching in ultra-high vacuum environments, suitable for connecting or disconnecting an ultra-high vacuum chamber from the external environment to achieve dynamic sealing of the ultra-high vacuum chamber, comprising an angle valve body and a valve stem, characterized in that, The sealing structure between the angle valve body and the valve stem includes: The dynamic sealing assembly consists of a liftable knife-edge structure and a liquid metal sealing medium to form a primary fluid seal; The static sealing component is located around the dynamic sealing component and includes an elastic sealing component and a sealing surface located on the angle valve body. When the dynamic sealing component is activated, it synchronously triggers the static sealing component to perform a secondary mechanical seal.

2. The metal-sealed angle valve for high-frequency switching in ultra-high vacuum environments according to claim 1, characterized in that: The liquid metal is contained in the angle valve body, and the angle valve body is opened and closed by inserting or withdrawing the blade structure into the liquid metal. When the knife-edge structure is inserted into the liquid metal for primary sealing, the elastic sealing component fits against the sealing surface, providing airtight isolation between the ultra-high vacuum cavity and the external environment, thus achieving secondary sealing; when the knife-edge structure is withdrawn from the liquid metal, the elastic sealing component leaves the sealing surface.

3. A metal-sealed angle valve for high-frequency switching in ultra-high vacuum environments according to claim 2, characterized in that: The angle valve body includes a bottom channel communicating with an ultra-high vacuum chamber, and the angle valve body surrounds the bottom channel, wherein a first annular groove is provided at the outlet located inside the valve for holding liquid metal. The blade structure is annular with a sharp lower end, designed to pierce the oxide layer on the surface of liquid metal.

4. A metal-sealed angle valve for high-frequency switching in ultra-high vacuum environments according to claim 3, characterized in that: The knife-edge structure is located on the bottom end face of the valve stem, and the diameter of the lower end of the valve stem is larger than the diameter of the outlet located inside the valve in the bottom channel.

5. A metal-sealed angle valve for high-frequency switching in ultra-high vacuum environments according to claim 3, characterized in that: The angle valve body includes a sealed and fixed upper cover and a lower housing with a flat top. The bottom channel is disposed through the lower housing, and the first annular groove is recessed on the top surface of the lower housing.

6. A metal-sealed angle valve for high-frequency switching in ultra-high vacuum environments according to claim 4, characterized in that: The elastic sealing component is a sealing ring, which is installed on the bottom end face of the valve stem.

7. A metal-sealed angle valve for high-frequency switching in ultra-high vacuum environments according to claim 6, characterized in that: The bottom end face of the valve stem has a second annular groove that is arranged around the outer periphery of the knife edge structure, and the sealing ring is installed in the second annular groove.

8. A metal-sealed angle valve for high-frequency switching in ultra-high vacuum environments according to claim 3, characterized in that: The vertical cross-section of the first annular groove is square.

9. A metal-sealed angle valve for high-frequency switching in ultra-high vacuum environments according to claim 5, characterized in that: The lower end of the lower housing is sealed with a lower flange.

10. A metal-sealed angle valve for high-frequency switching in ultra-high vacuum environments according to claim 3, characterized in that: The side of the upper cover is sealed with a side flange.

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