Flat compression seal gasket and seal system comprising the same

Abstract

To provide a compression seal gasket and seal system for gas-insulated portions of high or medium voltage equipment.SOLUTION: A seal system 1 comprises two components 3, 4 fastened together, in which the respective components 3, 4 comprise assembly faces 12, 13 and a compression seal gasket 2 that is disposed and compressed axially between the assembly faces 12, 13 of the components 3, 4. The compression seal gasket 2 comprises an annular main body 22 that is made of an elastomer material and has a main axis A. The main body 22 comprises a radially outer side, a radially inner side and end faces that connect the inner side and the outer side. The gasket 2 further comprises a lip 28 projecting from the end face parallel to the main axis A. The lip 28 engages a ring-shaped fixation groove 21 formed in an assembly face 12, 13 of one of the components 3, 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a compression seal gasket designed to reduce gas permeability and facilitate installation, and to a sealing system for a gas-insulated portion of high or medium pressure equipment that includes such a compression seal gasket at the connection of two pieces of gas-insulated equipment. [Background technology]

[0002] Some high-voltage or medium-voltage equipment contains hollow components in which conductors are located. An insulating gas fills these components, insulating the conductors carrying current at high voltage from the hollow components at ground potential. The insulating gas can withstand the dielectric field even over short distances between conductors located within the components. The insulating gas may be under pressure of at least 1 bar or several bars. Such gas-insulated equipment may include, for example, gas-insulated switches, circuit breakers, disconnectors, transformers, surge arresters, or gas-insulated substations or lines.

[0003] The connection between two parts of gas-insulated equipment is intended, for example, to prevent the insulating gas contained inside the equipment from leaking to the outside, or to prevent other gases in the atmosphere, such as water vapor, from penetrating into the interior and mixing with the insulating gas due to a higher partial pressure in the atmosphere than inside the cylindrical or tubular part.

[0004] According to a known embodiment, the sealing gasket is made of an elastomer and is compressed between clamped parts of a gas-filled device, for example, two tubular parts or a tubular part and a cover plate. The compression of the elastomer gasket by the parts causes elastic deformation that fills any gaps or roughness in the tubular parts on both sides, thereby closing or blocking any direct paths of internal and external gas from the inside to the outside or vice versa. The elasticity of this material improves the sealing of the connection.

[0005] However, gaskets made of elastomers are generally permeable to all gases, especially insulating gases, under high pressure. Although leakage of insulating gas around the gasket due to imperfect closure may be substantially effectively prevented by a sealing gasket compressed between two parts, gas molecules may penetrate through the elastomer material of the sealing gasket, a process known as permeation.

[0006] It is desirable to provide a sealing gasket with significantly lower permeability to insulating gases in order to reduce the leakage rate in the complete apparatus. In the intended application, the target leakage rate for the entire arrangement is less than 0.5% vol / year, as described in the relevant IEC standards for switchgear, e.g., IEC 62271-203 for gas-insulated switchgear.

[0007] This objective is particularly interesting because industry is increasingly using insulating gases and gas mixtures with molecular properties different from those of SF6, a potent greenhouse gas that has been used for decades, and which may result in different leak patterns.

[0008] In particular, as an alternative to SF6 gas, a switching and insulating gas called "g3," a diluent gas made from heptafluoroisobutyronitrile, is increasingly being used in combination with diluent gases containing carbon dioxide and oxygen. However, CO2 is prone to leaking. O2 and N2 also leak, but to a lesser extent. These three gases are more prone to leaking than SF6. Leakage is problematic because CO2 has a negative impact on the environment. Lost gas must also be replenished, resulting in maintenance costs.

[0009] WO 2022 / 152811 A1 discloses a sealing system including two cylindrical components arranged coaxially with each other and coaxially with a major axis. Each component includes an end face extending in a plane perpendicular to the major axis and facing the end face of the other component. A compression seal gasket is disposed between the end faces of the cylindrical components and is axially compressed. The compression seal gasket is made of an elastomeric material and includes an annular body having a major axis, with an annular radially outer side and an annular radially inner side that are parallel and coaxial with each other, and an annular end face formed in a corrugated shape to enhance sealing performance when the gasket is compressed between the cylindrical components. The gasket further includes an insert attached to the radially inner side of the gasket and positioned to reduce the cross-sectional area through which gas contained within the components can travel. The insert is made of a material that is significantly less permeable than the elastomeric body material.

[0010] Although known compression seal gaskets have the potential to improve sealing performance and significantly reduce the permeability of gaskets, which reduces the leakage rate of gas-insulated equipment, compression seal gaskets, which are assembled with a body and an insert made of different materials, are complex in structure and costly. It is desirable to simplify the structure of compression seal gaskets while ensuring the same level of gas tightness.

[0011] Another problem with compression seal gaskets is that they typically require a recess on at least one assembly surface of the equipment component to receive at least a portion of the gasket. This recess must be precisely formed to ensure a snug fit and prevent misalignment during assembly or operation. Misalignment can occur accidentally during assembly or during operation due to vibration of the equipment or internal pressure (up to 20 bar) of the gas contained within the equipment. Gasket misalignment can increase gas leakage and lead to premature equipment failure, requiring unexpected and premature repairs. Gasket displacement and the resulting gas leakage must be prevented in all operating positions, regardless of whether the gasket is mounted vertically, horizontally, or in any other position.

[0012] On the other hand, the receiving grooves of a compression seal gasket must have sufficient clearance to allow for expansion of the gasket as a result of compression between the assembly surfaces of the components, as well as thermal expansion and contraction without affecting sealing performance. Furthermore, a receiving groove for the gasket is not always necessary; the gasket can be easily received and compressed between spaced, flat assembly surfaces of the components. In all of these cases, it is desirable to provide an efficient seal while preventing the gasket from displacing during assembly and operation.

[0013] It is therefore an object of the present invention to provide a low permeability compression seal gasket that effectively prevents displacement of the compression seal gasket during assembly and / or operation while reducing the gas leakage rate in the complete device.

[0014] In particular, the object of the present invention comprises means for securely fixing a compression seal gasket in a gas of the type mentioned above, in particular in gas-insulated devices of the type mentioned above, in particular in high-voltage or medium-voltage components implemented in medium-voltage or high-voltage applications, such as circuit breakers, switches, circuit breakers, gas-insulated lines, etc., to facilitate the installation and use of the gasket in any desired installation and / or operating position.

[0015] Another object of the present invention is to provide a sealing system, particularly for gas-insulated high or medium voltage equipment, with such an improved sealing gasket that is easy to assemble and use. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] International Publication No. 2022 / 152811 Summary of the Invention

[0017] To achieve the above-mentioned objectives and obviate at least some of the above-mentioned drawbacks, according to a first aspect of the present invention, there is provided a compression sealing gasket, comprising: a ring-shaped main body made of an elastomer material and having a main axis, the main body having a generally flat planar configuration that extends perpendicular to the main axis and comprising a radially outer side, a radially inner side, and end faces which delimit the main body along the main axis and connect the inner side and the outer side. The gasket further includes a lip projecting from the main body in an axial direction parallel to the main axis beyond one of the end faces, the lip arranged in a distance to both the inner side and the outer side of the main body.

[0018] The present disclosure provides a compression sealing gasket with an improved sealing design showing a low permeability to gases and reducing the leaking rate for a gas-insulated apparatus. With the generally flat planar configuration of the main body, the gasket may be made sufficiently long and thin to offer only a small surface area for the insulating gas to penetrate or to be absorbed by the gasket material and to effectively damp gas permeation in the radial direction, i.e., the length direction of the main body. Permeation, that is, the process of penetration of gas molecules through the gasket by diffusion, is linked to the surface area under pressure.Due to the small thickness in the axial direction, the gasket offers a very small surface area for the inside gas to be absorbed and to permeate through the gasket material to the outside and to be desorbed to the atmosphere.

[0019] Thus, gaskets according to the present disclosure are highly effective in sealing against leakage of insulating gases used in medium or high voltage applications, such as the gas-containing high or medium voltage apparatuses, e.g., disconnectors, switches, circuit breakers, gas-insulated lines, or substations. As the insulating gas, SF or g gases, alone or mixed with O, CO, N, or any other appropriate gases, may be used, and the gases may be under pressure comprised between 1 bar and 20 bar, for example.

[0020] The lip and body together form a roughly T-shaped seal gasket. The lip acts as a locking lip, securing the gasket in its operating position and preventing it from moving, shifting, or falling off during installation and operation, even in situations where the equipment is subject to high vibration or where the internal gas pressure acting directly on the gasket is very high. The locking lip is positioned to engage a corresponding locking groove in one of the gas-insulated equipment components, preventing the gasket from moving, shifting, or falling off during assembly in any mounting position, including sideways, overhead, or 'from the top' mounting. The small locking lip securely holds the gasket in place in horizontal, vertical, inclined, and other orientations. Grease, typically used to secure or hold a conventional O-ring gasket in place on a tubular component during installation of a second tubular component, is no longer required for any mounting method, including overhead mounting, because the lip securely holds the gasket in place. Because grease is not required during gasket installation, this invention provides a solution for low-temperature applications where grease installation is prohibited due to grease crystallization, which adversely affects sealing performance. The small lip does not add significant material to the gasket body and does not significantly increase the gasket's complexity or cost. Meanwhile, the lip offers the advantage of securely seating the gasket without requiring a specifically shaped receiving recess in the equipment component and without limiting the gasket's ability to expand under compression or high temperature conditions.

[0021] In preferred embodiments of the gasket, the body may have an annular, oval, or ellipsoidal shape in a radial plane perpendicular to the major axis. Annular sealing gaskets are preferably used in the applications related to this specification. They are very effective and easy to handle. Other ring shapes of gaskets are also possible.

[0022] The gasket body may preferably have a generally rectangular cross section in an axial plane containing the major axis. In some embodiments, the cross section of the body may be exactly rectangular, i.e., the radially outer and inner sides may be parallel planes or may be coaxial, and the end faces may also be substantially planar and extend parallel to each other. In other embodiments, at least the radially outer and inner sides may be tapered and convexly curved, for example, to reduce or eliminate contact pressures and loads at the radially outer and inner end portions. This allows the radial end portions to freely expand and contract as needed.

[0023] In some embodiments of any of the gaskets described above, the end surface defining the axial body may have at least a portion thereof that is convexly curved or wavy. Thus, during use of the gasket, there may be high-compression regions where the contact pressure is increased and sealing performance is improved, and low-compression regions where the compression and contact pressure are reduced. The low-compression or low-contact-pressure regions may reduce the load on the gasket in certain areas, for example, to avoid the risk of damage to the ring-shaped or annular end surface or lip or negative aging effects (e.g., tearing or wear). Thus, convex regions or crests or ridges on the end surface may provide high-compression regions that enhance sealing performance, while locally thinned regions of the body or troughs on the end surface may enhance the robustness, integrity, and durability of the gasket.

[0024] In an advantageous embodiment, the body may have a cross-sectional structure approximately in the center or centre of the planar extension in the radial direction. When the gasket is installed and compressed between parts of a device, this design creates a low compression or relief zone in the radial centre or centre of the gasket, and the locking lip is preferably also located at this position. This avoids or at least reduces the risk of damage to the lip, such as tearing. While avoiding or at least reducing the risk of tearing or other damage to the lip, the high compression or contact pressure zones between the cross-sectional structure and the radially inner and outer sides of the body ensure sufficient leak protection.

[0025] In a preferred embodiment of any of the gaskets described above, the lip may be located approximately in the middle or center of the radial extension of the body. The lip may extend in the form of a complete ring around the entire circumference of the body, or may be closed on itself. This provides a simple and clear structure and facilitates stable fixing of the gasket in its respective annular fixing groove. Alternatively, the lip may be divided circumferentially.

[0026] Preferably, the lip of the gasket according to any of the above embodiments may be integrally formed, i.e., integrally formed with the body and made of the same material as the body. This facilitates the manufacture of a sealing gasket having a body-lip combination. The entire gasket can preferably be manufactured using the same manufacturing process, such as injection molding of a non-vulcanized (or uncured) elastomeric material in a mold, followed by a compression and curing step.

[0027] Preferably, the entire gasket, including the body and lip, is made from a single material, such as, but not limited to, an elastomer such as unmodified butyl rubber or modified butyl rubber, e.g., chlorobutyl (CIIR) or bromobutyl (BIIR) rubber or halogenated butyl rubber (XIIR). Mixtures of these materials can also be used. The materials employed are low-cost, particularly suited to the intended sealing function, and can reduce, though not completely prevent, gas permeation through the material. The elongated design of the gasket combined with the materials employed ensures sufficient airtightness.

[0028] In some embodiments of the gasket described above, the lip may include a rounded head and a connecting portion connecting the head and the body. The connecting portion may have a radial width perpendicular to the major axis that is smaller than the corresponding width of the head to provide some flexibility for easier insertion. The rounded head and head width may be selected in combination with the dimensions of the locking groove in the device component so that the lip makes substantially line contact with the side of the locking groove, thereby providing high contact pressure for improved sealing performance at the head.

[0029] An important feature of the gaskets of the present disclosure is the elongated design of the body, which has a ratio of radial length perpendicular to the major axis to axial thickness parallel to the major axis of at least 5, preferably at least 7, and most preferably about 8 to 12. Because molecular permeation through a gasket by gas diffusion is a function of both the surface area under pressure and the diffusion length, the body advantageously reduces the surface area for permeation and extends the length, significantly reducing gas permeation.

[0030] To facilitate insertion of the lip into the fixing groove and ensure retention of the gasket, the axial height of the lip may be greater than the thickness of the body, and preferably the height of the lip is at least 1.5 times the thickness of the body.

[0031] The gaskets of the aforementioned embodiments may have relatively large dimensions if required for the particular application. For example, the inner dimension, e.g., the maximum inner diameter of an elliptical or ellipsoidal gasket, or the inner diameter of an annular gasket, may be between 40 mm, or 100 mm and 500 mm, or 1300 mm. In preferred embodiments, it may be between 100 mm and 300 mm, and most preferably about 200 mm.

[0032] To achieve the above-mentioned objectives and overcome at least some of the drawbacks discussed in the background art, one aspect of the present invention provides a sealing system for a gas-insulated portion of high-voltage or medium-voltage equipment. The sealing system includes two components secured together, each component having an assembly face opposing the assembly face of the other component. The sealing system further includes a compression seal gasket according to any of the above-described embodiments. The gasket is positioned and axially compressed between the assembly faces of the cylindrical components.

[0033] The present invention provides a sealing system having a flat, substantially T-shaped, ring-like, preferably annular, gasket that is clamped and compressed between opposing assembly or sealing surfaces of interconnected equipment components, which may benefit from the advantages of each of the compression seal gasket embodiments described above.

[0034] In a preferred embodiment, the two parts of the device are preferably cylindrical and / or tubular and may be coaxially positioned relative to each other and to the major axis of the compression seal gasket. The parts may be secured to each other using suitable fastening means, such as bolts and nuts, that facilitate adjusting the required or desired compression force and pressure on the gasket.

[0035] In any of the above-described sealing systems, at least one of the assembly surfaces of the components may include at least one recess into which a compression seal gasket may be placed, although, in view of the locking lip, a receiving groove for the gasket body is not necessarily required and may be omitted.

[0036] One of the assembly surfaces of the two parts may define a preferably annular locking groove arranged to receive the lip of the gasket under slight compression in a radial direction perpendicular to the major axis, and preferably a substantially linear compressive contact may be established between the rounded head of the lip and the associated inside of the locking groove.

[0037] In a preferred embodiment of any of the above-mentioned sealing systems, in the operating state of the gasket, the body may have an average compressibility comprised between 10% and 30%, preferably between 15% and 25%. Such an average compressibility may reduce both the leakage of gas around the body and the penetration therethrough. Advantageously, the average compressibility of the body may be higher than the average compressibility of the lip.

[0038] In some embodiments, the gasket may be assembled with a thin film of grease. The thin film of grease generally improves gasket slippage, ensures adhesion, prevents tearing, cutting, crushing, and abrasion of elastomeric gaskets, prevents dirt penetration to the component surfaces, reduces the labor required for gasket assembly, and may prevent gasket migration. Due to the advantageous design of the gasket, including the locking lip, only a small amount of grease is required. In some embodiments, the gasket may be assembled without grease. Reducing the amount of grease may reduce the risk of grease crystallization in low-temperature applications, e.g., −40° C. to −50° C., potentially reducing the associated costs.

[0039] In a preferred embodiment of any of the above-described sealing systems, the gas insulated portion of the high or medium voltage equipment may form part of a gas-insulated switch, circuit breaker, disconnector, transformer, surge arrester, a gas-insulated substation or a gas-insulated line. The gas used in such equipment may include a gas containing at least one of the following: - SF6 gas, - Heptafluoroisobutyronitrile and / or heptafluoroisopropyl trifluoromethyl ketone (also known as 2-butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl) - (CAS No. 756-12-7)), possibly mixed with gases or diluents, containing at least CO2 and / or O2 and / or N2 and / or oxygen compounds; and A gas containing at least CO2 and / or O2 and / or N2 and / or oxygen compounds and / or water vapor.

[0040] The gas may be contained within the device at a pressure of from 1 bar to 20 bar, preferably from 5 bar to 15 bar.

[0041] Details of advantageous embodiments of the invention can be taken from the dependent claims, the drawings and the associated description. [Brief explanation of the drawings]

[0042] These and other features of the present invention will be more readily understood by reference to the following detailed description of various aspects of the invention, as well as the accompanying drawings illustrating various exemplary embodiments of the present invention, in which like reference numerals are used to designate like elements in all figures. [Figure 1] 2 shows, in a schematic, partial cross-sectional view, a portion of a high voltage apparatus including two components assembled using the compression seal gasket of FIG. 1. [Figure 2] Figure 2a shows the compression seal gasket of Figure 1 in isolation in perspective, and Figure 2b shows the gasket of Figures 1 and 2a in an enlarged, partial cross-sectional view. [Figure 3] 2 is a schematic partial cross-sectional view similar to FIG. 1 showing a portion of a high voltage apparatus including two components assembled using a compression seal gasket according to a second embodiment of the present invention. [Figure 4] Figure 4a is a schematic, partial cross-sectional view showing a detail of the device of Figure 3 with the gasket in an uncompressed state, and Figure 4b is a schematic, partial cross-sectional view similar to Figure 4a showing a detail of Figure 4a with the gasket in a compressed state. [Figure 5] Figure 5a shows, in a schematic, partial cross-sectional view, a portion of a high voltage apparatus including two components assembled using a compression seal gasket according to a third embodiment of the invention, with the gasket in an uncompressed state, and Figure 5b shows, in a schematic, partial cross-sectional view, a portion of the apparatus of Figure 5a with the gasket in a compressed state. DETAILED DESCRIPTION OF THE INVENTION

[0043] 1 shows an example of a sealing system 1 according to the invention, to which a compression seal gasket 2 according to the invention can be applied. In particular, the sealing system 1 comprises a portion of a high or medium voltage apparatus consisting of two assembled parts 3, 4. In the example shown, the first part 3 is represented as a cylindrical cover 6 fastened to a cylindrical flange 7 of a tubular enclosure or housing 8 forming the second part 4. Both parts 3, 4 extend coaxially with the main axis A of the high voltage apparatus.

[0044] It should be understood that the two components 3, 4 may have other shapes. For example, they may both be cylindrical or tubular, or they may be non-cylindrical tubular components that are assembled and sealed using gasket 2. The device may be any gas-insulated medium or high-voltage device, including gas-insulated electrical and / or electronic devices and / or conductors. In its intended application, the device may be a gas-insulated switch, circuit-breaker, disconnector, transformer, surge arrester, a gas-insulated substation, a gas-insulated line, or the like.

[0045] The gas includes at least one of the following: - SF6 gas; - a gas consisting of heptafluoroisobutyronitrile and / or heptafluoroisopropyl trifluoromethyl ketone (also known as 2-butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl) - (CAS No. 756-12-7)), possibly mixed with a diluent gas or gases (containing at least CO2 and / or O2 and / or N2 and / or oxygen compounds); - Gases containing at least CO2 and / or O2 and / or N2 and / or oxygen compounds and / or water vapor.

[0046] This gas may be pressurized gas, for example, contained within the device, preferably at a pressure between 5 and 15 bar. It is therefore necessary and desirable to hermetically seal the connection between the parts 3, 4 so that the gas contained within the device interior 9 does not leak out to the device exterior 11. For this purpose, a sealing system 1 according to the present invention is provided.

[0047] 1, sealing system 1 generally includes at least a portion of components 3, 4 and a compression seal gasket 2. Component 3 has an end face or assembly surface 12, and component 4 has an end face or assembly surface 13 opposite and connected to assembly surface 12 of component 3.

[0048] The sealing gasket 2 is axially disposed between the assembly surfaces 3, 4 of the two components 3, 4. The gasket 2 is substantially flat and extends substantially in a plane perpendicular to the main axis A. In the example shown, the sealing gasket 2 is generally annular and has circular symmetry about the axis A. Figure 2a shows a perspective view of the sealing gasket 2 according to a first embodiment of the invention. The sealing gasket 2 is described in more detail below.

[0049] The sealing system 1 further includes a fastening means 14, such as a bolt 16 and nut 17, or other bolting or clamping means, which axially presses the parts 3, 4 together and holds the fastened parts 3, 4 tightly together. The fastening means 14 axially compresses the sealing gasket 2 and provides an airtight connection between the two parts 3, 4.

[0050] 1, 2a, and 2b, the assembly surfaces 12, 13 of the components 3, 4 each include annular recesses 18, 19 for receiving at least a portion of the sealing gasket 2. A first recess 18, which receives a portion of the gasket 2, is formed as a cylindrical recess in the assembly surface 12 of the gasket 2, and a second recess 19, which receives another portion of the gasket 2, is formed as an annular recess facing the first recess 18 in the assembly surface 13 of the component 4.

[0051] The sum of the axial depths of the two recesses 18, 19 is less than the axial height H of the body 22 of the gasket 2 before the two parts 3, 4 are assembled, this axial height H being measured along an axis perpendicular to the plane in which the gasket 2 extends, or along the main axis A.

[0052] In an alternative embodiment, one of the parts 3, 4 has only one recess and the other part has no recess and a substantially planar assembly surface, the axial depth of the single recess being less than the axial height H of the body of the gasket 2 before the two parts 3, 4 are assembled.

[0053] In a further alternative embodiment not shown herein, both the first and second recesses 18, 19 may be omitted and the assembly surfaces 12, 13 of both components 3, 4 may be formed as substantially planar surfaces. In that case, the gasket 2 may contact the assembly surfaces 12, 13 of both components 3, 4, maintaining the assembly surfaces 12, 13 spaced apart from one another. In that case, the radial sides of the gasket 2 are not pinched by the recesses in the assembly surfaces 12, 13.

[0054] In either case, one of the assembly surfaces 12, 13 is formed with a locking groove 21 for receiving a locking lip of the gasket 2 (described in more detail below) to secure the gasket 2 to the respective component. In the exemplary embodiment shown in Figure 1, the locking groove 21 is formed in the assembly surface 13 of the flange 7 of the component 4 and is an annular groove extending coaxially with the main axis A.

[0055] Compression of the gasket 2 by the clamping means 14 causes axial deformation of the gasket 2, keeping the gasket 2 effectively pressed against the assembly surfaces 12,13 and the walls of the recesses 18,19 or assembly surfaces 12,13.

[0056] As shown in FIG. 1 and with further reference to FIGS. 2a and 2b, gasket 2 includes a body 22 made of an elastomer, such as, by way of non-limiting example, unmodified butyl rubber or modified butyl rubber, for example, chlorobutyl (CIIR) or bromobutyl (BIIR) rubber or halogenated butyl rubber (XIIR), or mixtures thereof. This material is cost-effective and suitable for the intended sealing operation. However, it remains highly gas-permeable; that is, gas molecules can diffuse through the material of gasket 2. The permeability of the elastomer to the gas filling components 3 and 4 results in gas loss over time.

[0057] As can be seen in Figures 1, 2a, and 2b, the body 22 has an annular shape that is circularly symmetric about the axis A, which, in the assembled state, defines the main axis A of the portion of the device shown in Figure 1. It has a generally flat, planar shape that extends perpendicular to the main axis A. The body 22 is composed of a radially outer side 23 and a radially inner side 24 relative to the main axis A, and end faces 26, 27 that define the body 22 along the main axis A and connect the inner side 24 to the outer side 23. The outer and inner sides 23, 24 are substantially planar in this exemplary embodiment, and are parallel and coaxial with each other and with the main axis A. The end faces 26, 27 of the body 22 are also substantially planar, such that the body 22 has a generally rectangular cross-section in an axial plane that includes the main axis A, as shown in Figures 1 and 2b. The first end face 26 is in contact with the assembly surface 12 of the part 3 and the second end face 27 of the body 22 is in contact with the assembly surface 13 of the part 4 .

[0058] It should be noted that in alternative embodiments, the end faces 26, 27 may also be curved, for example convexly curved or wavy, to affect the sealing performance of the gasket 2. Alternatively or additionally, the body 22 may have a non-annular shape in a radial plane perpendicular to the major axis A, for example an elliptical or ellipsoidal shape, or a rectangular, polygonal, or irregular shape, depending on the application and requirements.

[0059] To secure the gasket 2 to the device and prevent movement or displacement of the gasket 2 during operation, the gasket 2 further includes a securing lip 28 that projects axially outward from an end face of the body 22, in this example, a second end face 27 of the body 22, beyond the end face 27 and parallel to the major axis A. The lip 28 is spaced apart from both the inner side 24 and the outer side 23 of the body 22. In the preferred embodiment shown, the lip 22 is centrally located in the radial extension of the body 22, thereby giving the sealing gasket 2 a generally T-shaped configuration. The lip 22 extends as a complete ring around the entire circumference of the body 22 so as to be self-closed. In an alternative embodiment, the lip 22 may be circumferentially segmented rather than forming a continuous annular ring.

[0060] 1, it can be seen that the locking lip 28 is received in the locking groove 21 in the assembly surface 13 of the part 4. The lip 28 is press-fit into the locking groove 21 and is slightly compressed to secure it in place.

[0061] With particular reference to Figure 2b, it can be seen that lip 28 includes a rounded head 29 and a connecting portion 31 connecting head 29 to body 22. Connecting portion 31 has a radial width W CP but the corresponding width W of the head 29 H Smaller than the width W of the head 29 His slightly smaller than the width of the fixing groove 21, so that the rounded head 29 is slightly compressed by the sides of the fixing groove 21. Preferably, a substantially linear pressure contact is established between the rounded head 29 and the sides of the fixing groove 21. This substantially linear contact results in a high contact pressure that improves the sealing ability of the head 29 to prevent gas from passing or leaking around the head 29.

[0062] In a preferred embodiment of the present invention, lip 22 is integrally, i.e., unitarily, formed with body 22 and is formed of the same elastomeric material as body 22. Preferably, the entire gasket 2, including body 22 and securing lip 28, may be manufactured in the same manufacturing process, such as by injection molding an unvulcanized or uncured elastomeric material into a mold, followed by compression and curing steps as necessary. Suitable elastomeric materials are described above in connection with body 22.

[0063] The sealing system 1 constructed in the manner described above is handled and operated as follows.

[0064] To seal a device, in particular a medium or high voltage device containing insulating gas, the gasket 2 is placed between the assembly faces 12, 13 of the two parts 3, 4, for example in the respective recesses 18, 19, while the fixing lip 28 is inserted into the fixing groove 21 of the assembly face 13. The width W of the connecting portion 31 CP The width W of the head 29 H , and the sufficient length of the lip 28 allows a degree of flexibility to facilitate insertion of the lip 28 into the fixing groove 21. The axial height H of the lip 28 is preferably greater than the thickness T of the body 22, and is preferably at least 1.5 times the axial thickness T of the body 22. The lip 28 is received in a slightly compressed state between the sides of the fixing groove 21 so as not to impede introduction, and is securely held within the fixing groove 21.

[0065] The gasket 2 can be assembled with a small amount of grease to ensure the gasket 2's tight seal and prevent tearing, cutting, crushing, and peeling of the elastomeric gasket. The grease reduces the labor required to assemble the gasket and also serves to prevent gasket movement in conventional sealing systems. Considering the provision of the locking lip 28, the amount of grease can be significantly reduced, or the sealing gasket 2 can be used without grease. This reduces, if not eliminates, the risk of grease crystallization at low temperatures, potentially enabling the gasket 2 to be used in applications requiring extremely low temperatures, such as -50°C. This potentially results in significant savings in assembly labor and costs.

[0066] Once the gasket 2 is properly positioned and secured using the locking lip 28, the fastening means 14 may be tightened to securely fasten the components 3 and 4 and compress the gasket 2 to the desired and necessary degree. The device may then be filled with the desired gas. In a preferred embodiment of the present invention, in the gasket's operating state, the body 22 may have an average compression ratio comprised between 10% and 30%, preferably between 15% and 25%. Such an average compression ratio has proven optimal for minimizing gas penetration while ensuring the integrity and durability of the gasket 2 over time.

[0067] The average compression rate of the body 22 is higher than the average compression rate of the lip 28 in the fixing groove 21 because the rounded head 29 only makes line contact with the side of the fixing groove 21, preventing leakage around the lip 28.

[0068] The planar configuration of the body 22 of the gasket 2 of the present invention, combined with a specific average compressibility, results in high gas-tightness of the gasket 2. The compressed body 22 has a relatively large length under gas pressure, which reduces the surface area exposed to the gas, thereby significantly reducing gas diffusion or penetration. The ratio of the length L of the body 22 in the radial direction to the thickness T in the axial direction is at least 5, preferably at least 7, and most preferably about 8-12.

[0069] In the preferred embodiment shown, the ratio of length L to thickness T is about 10. The thickness T is about 3 mm, the height H of the lip 28 is about 5 mm, and the width W of the connecting portion is about 10. CP is about 4 mm, and the width W of the head 29 H The inner diameter of the gasket 2 in the preferred embodiment shown is about 200 mm and the outer diameter is about 260 mm.

[0070] The dimensions of the gasket and its parts can be selected according to the needs and requirements of the respective application. The gasket 2 according to the invention can be manufactured with relatively large internal dimensions or diameters, which can be, for example, between 40 mm, 55 mm, or 100 mm on the one hand, and between 500 mm or even 1300 mm on the other. Such large gaskets are more critical in terms of airtightness than the smaller gaskets typically used, for example, with a diameter of less than 40 mm.

[0071] Even with such a large gasket, the fixing lip 28 ensures stable retention of the gasket 2 in each operating position, regardless of whether the gasket 2 is in a vertical, horizontal, or other orientation. In the past, large vibrations of the device or the high pressure of the insulating gas sealed within the device could cause the sealing gasket to move or become displaced. In the structure of the present invention, the lip 28 engaging with the fixing groove 21 reliably prevents the gasket 2 from moving or becoming displaced during operation, even though the gasket 2 is directly exposed to the internal gas pressure.

[0072] Tests using the sealing system 1 of the present invention have shown that for the above-mentioned applications, gas types, and gas pressures, the sealing system 1 of the present invention can significantly improve the leak tightness of the equipment and provide a leakage rate of less than 0.5% vol / year, thereby complying with relevant IEC standards, such as IEC Standard 62271-203 for Gas-Insulated Switchgear.

[0073] Figures 3, 4a and 4b show another embodiment of a sealing system 1 according to the present invention. To the extent that the structure and / or function coincides with the first embodiment described above of the sealing system 1 and compression seal gasket 2 according to Figures 1, 2a and 2b, the same reference numerals are used to refer to the above description.

[0074] The second embodiment of the sealing system 1 according to FIGS. 3, 4a, and 4b differs from the first embodiment according to FIGS. 1, 2a, and 2b only in the shape of the gasket 2', specifically the shape of the body 22' of the gasket 2'. In contrast to the gasket 2, the radially outer and inner sides 23', 24' of the body 22' of the gasket 2' are not flat or parallel to each other, but are rounded or convexly curved. In particular, the outer and inner sides 23', 24' may be elliptical. This configuration reduces the compression pressure at the radial ends of the gasket 2' during operation and also facilitates radial expansion of the gasket 2' in response to compression and / or thermal expansion. Furthermore, the shape of the gasket 2' reduces material and manufacturing costs.

[0075] As can be seen in Figures 4a and 4b, the body 22' of the gasket 2' may be comprised of a central portion 32 bounded by substantially planar end faces 26, 27 and tapered ends 33, 34 that are substantially semicircular or semi-elliptical in shape and bounded by rounded radially outer and inner sides 23', 24'. In the uncompressed state shown in Figure 4a, the thickness T of the body 22' at the central portion 32 is substantially greater than its thickness in the compressed state shown in Figure 4b. As noted above, the average compression ratio is comprised between 10% and 30%, preferably between 15% and 25%.

[0076] When the gasket 2' is compressed, the configuration of the end portions 33, 34 facilitates the expansion of the gasket 2' in both radial directions. Due to the provision of sufficient clearance between the radially outer and inner sides 23', 24' of the gasket 2', on the one hand, and the opposite sides of the recesses 18, 19 or the interior space of the device, on the other hand, end 33 can easily expand radially outward and end 34 can easily expand radially inward as a result of compression between the assembly surfaces 12, 13 of the components 3, 4.

[0077] 4a and 4b, it can be seen that the length of the body 22' of the gasket 2' increases significantly in the compressed state. Advantageously, this significantly reduces the surface area under pressure exposed to the gas, significantly increasing the length of the gasket 2', particularly the body 22', thereby minimizing gas permeation or diffusion through the body 22'. The gasket 2' can achieve a very low leakage rate of insulating gas in gas-insulated high- or medium-voltage equipment and provide a very gas-tight connection between the components 3 and 4.

[0078] Additionally, the low compression zones at the ends 33, 34 of the body 22' significantly reduce tearing and wear at these locations that would normally be prone to tearing and wear due to compression. Combined with a reduced leakage rate of the insulating gas, this improves the durability of the gasket 2' and allows for longer service intervals for the device.

[0079] Figures 5a and 5b show a third embodiment of a sealing system 1 according to the present invention. Again, to the extent that there is structural and / or functional agreement with the first or second embodiments described in Figures 1 to 4b, the same reference numerals are used to refer to the above description.

[0080] The embodiment of the sealing system 1 according to Figures 5a and 5b corresponds to the second embodiment shown in Figures 3, 4a and 4b in that the body 22" of the gasket 2 also comprises convexly curved circular or elliptical outer and inner portions 23", 24" which define tapered, semicircular or elliptical end portions 33, 34. In contrast to the second embodiment, the body 22' of the gasket 2" of the third embodiment of Figures 5a and 5b further comprises a cross-sectional constriction 36 in the radial central portion 32 perpendicular to the main axis A approximately in the middle or centre of the planar extension of the body 22". This cross-sectional constriction 36 may be formed by a recess 37, 38 formed in the end faces 26, 27 in the centre of the central portion 32.

[0081] The regions of the body 22 between the cross-sectional constriction 36 and the end portions 33, 34 have planar end surfaces 26, 27, although in alternative embodiments, the end surfaces 26, 27 in these regions may also be convexly curved or wavy. In either case, the cross-sectional constriction 36 in combination with the tapered end portions 33, 34 may create areas of low gasket compression in the central and end portions 33, 34 of the central portion 32 of the gasket 2" during operation of the compression seal gasket 2", thereby reducing the loads and corresponding risk of tearing, wear, and damage in these areas. The cross-sectional constriction 36 may also reduce the load on the fixed lip 28. Furthermore, the regions between the cross-sectional constriction 36 and the end portions 33, 34 form areas of high gasket compression, which results in an efficient seal and a low leak rate.

[0082] A compression seal gasket 2, 2', 2" and a seal system 1 for gas-insulated parts of high-voltage or medium-voltage equipment are disclosed. The seal system 1 is composed of two parts 3, 4 fixed together, each part 3, 4 having an assembly surface 12, 13 facing the assembly surface 13, 12 of the other part 4, 3, and a compression seal gasket 2, 2', 2" disposed between the assembly surfaces 12, 13 of the parts 3, 4 and compressed in the axial direction. The compression seal gasket 2, 2', 2" includes a ring-shaped, preferably annular, body 22, 22', 22" made of an elastomeric material and having a major axis A. The body 22, 22', 22" has a generally flat planar configuration extending perpendicular to the major axis A and includes a radially outer side 23, 23', 23", a radially inner side 24, 24', 24", and end faces 26, 27 that define the body 22, 22', 22" along the major axis A and connect the inner side 24, 24', 24" to the outer side 23, 23', 23". The gasket 2, 2', 2" further includes a lip 28 that projects axially outward from the body 22, 22', 22", beyond one of the end faces 26, 27 and parallel to the major axis A. The lip 28 is positioned at a distance both on the inside 24, 24', 24" and on the outside 23, 23', 23" of the body 22, 22', 22", and engages in a ring-shaped fixing groove 21 formed in one of the assembly surfaces 12, 13 of the parts 3, 4. The fixing groove 21 receives the lip 28 of the gasket 2, 2', 2" with slight compression, thereby preventing movement or displacement of the gasket 2, 2', 2" during operation. [Explanation of symbols]

[0083] 1: Sealing system 2, 2', 2": Gasket / compression seal gasket 3, 4: Part 6: Cylindrical cover 7: Cylindrical flange 8: Tubular enclosure / housing 9: Inside the device 11: Outside the device 12, 13: Assembly surface 14: Fastening means 16: Bolt 17: Nut 18, 19: Annular recess 21: Fixing groove 22, 22', 22": Body 23, 23', 23": Radially outer 24, 24', 24": Radially inner 26, 27: End face 28: Lip 29: Head 31: Connection part 32: Central part 33, 34: Tapered end part 36: Cross-sectional reduction part A: Main axis H: Lip height L: Radial length T: Axial thickness WCP: Radial width WH: Head width

Claims

1. A compression seal gasket (2, 2', 2"), a ring-shaped body (22, 22', 22") made of an elastomeric material and having a major axis (A), the body (22, 22', 22") having a generally planar configuration extending perpendicular to the major axis (A), the body (22, 22', 22") including a radially outer side (23, 23', 23"), a radially inner side (24, 24', 24"), and end faces (26, 27) that define the body (22, 22', 22") along the major axis (A) and connect the inner side (24, 24', 24") and the outer side (23, 23', 23"); a lip (28) projecting from the body (22, 22', 22") in an axial direction parallel to the main axis (A) beyond one of the end faces (26, 27); Including, Lips (28) are spaced apart on both the inside (24,24',24") and outside (23,23',23") of the body (22,22',22") of the gaskets (2,2',2").

2. 2. The gasket (2, 2', 2") according to claim 1, wherein in a plane perpendicular to the major axis (A), the body (22, 22', 22") has a circular, elliptical or ellipsoidal shape.

3. 2. A gasket (2, 2', 2") according to claim 1, wherein in an axial plane containing the major axis (A), the body (22, 22', 22") has a generally rectangular cross section.

4. 2. The gasket (2, 2', 2") according to claim 1, wherein the outer side (23, 23', 23") and the inner side (24, 24', 24") each have a tapered shape, and / or the end faces (26, 27) have at least a portion thereof a convexly curved shape or a wave-curved shape.

5. 2. The gasket (2, 2', 2") according to claim 1, wherein the body (22, 22', 22") has a cross-sectional constriction (36) approximately in the middle of a radial planar extension perpendicular to the major axis (A).

6. 2. The gasket (2, 2', 2") of claim 1, wherein the lip (28) is located in the center of the radial extension of the body (22, 22', 22") and extends in the shape of a complete ring around the entire circumference of the body (22, 22', 22").

7. 2. The gasket (2, 2', 2") according to claim 1, wherein the lip (28) is integrally formed with the body (22, 22', 22") and made of the same material as the body (22, 22', 22").

8. The lip (28) includes a rounded head (29) and a connecting portion (31) connecting the head (29) to the body (22, 22', 22''), and the connecting portion (31) preferably has a radial width (W) perpendicular to the main axis (A). ＣＰ ) is the corresponding width (W Ｈ 2. The gasket (2, 2', 2") according to claim 1, wherein the gasket (2, 2', 2") is smaller than

9. 2. The gasket (2, 2', 2") according to claim 1, wherein the body (22, 22', 22") has a ratio of a radial length (L) perpendicular to the main axis (A) to an axial thickness (T), said ratio being at least 5, preferably at least 7, and most preferably between 8 and 12.

10. 10. The gasket (2, 2', 2") according to claim 9, wherein the height (H) of the axial lip (28) is greater than the thickness (T) of the body (22, 22', 22"), preferably at least 1.5 times the thickness (T) of the body (22, 22', 22").

11. A sealing system (1) for gas-insulated parts of high-voltage or medium-voltage equipment, comprising: two parts (3, 4) fixed to one another, each part (3, 4) including an assembly surface (12, 13) facing an assembly surface (13, 12) of the other part (4, 3); A compression seal gasket (2, 2', 2") according to any one of claims 1 to 0; Including, A sealing system (1) in which gaskets (2, 2', 2'') are placed between assembly surfaces (12, 13) of parts (3, 4) and are axially compressed.

12. The sealing system (1) according to claim 11, wherein at least one assembly surface (12, 13) comprises a recess (18, 19) in which a compression sealing gasket (2, 2', 2'') is placed.

13. 12. The sealing system (1) according to claim 11, wherein one of the assembly surfaces (12, 13) comprises a ring-shaped fixing groove (21) arranged to receive with slight compression a lip (28) of the gasket (2, 2', 2") in a radial direction perpendicular to the main axis (A).

14. 12. The sealing system (1) according to claim 11, wherein in an operating state of the gasket (2, 2', 2"), the body (22, 22', 22") has an average compressibility of 10% to 30%, preferably 15% to 25%, and the average compressibility of the body (22, 22', 22") is higher than the average compressibility of the lip (28).

15. the gas-insulated part forms part of a gas-insulated switchgear, a gas-insulated circuit breaker, a gas-insulated disconnector, a gas-insulated transformer, a gas-insulated surge arrester, a gas-insulated substation, or a gas-insulated electric cable; and / or The gas insulating portion contains a gas including at least one of the following: - Science fiction ６ gas, Heptafluoroisobutyronitrile and / or heptafluoroisopropyl trifluoromethyl ketone (also known as 2-butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)- (CAS No. 756-12-7)), optionally with at least CO ２ and / or O ２ and / or N ２ and / or mixed with a gas containing an oxygen-containing compound or a diluent gas; - at least CO ２ and / or O ２ and / or N ２ and / or a gas containing oxygenated compounds and / or water vapor, and / or 12. The sealing system (1) according to claim 11, wherein the gas is contained in the device at a pressure between 1 bar and 20 bar, preferably between 5 bar or 15 bar.

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