Compression sealing gasket and sealing system

Abstract

A compression sealing gasket having a main body of general planar extension, or extending in a plane, including an inner side and an outer side, and end faces, which delimit the gasket along an axis perpendicular to the plane, and connect the inner side and the outer side, made of an elastomer material, the main body having a first extension, along the axis, at least one of the inner side and the outer side being provided with a lip which has a second extension, along the axis perpendicular to the plane, less than the first extension.

Claims

1. A sealing system comprising two components of a gas insulated portion of a high or medium voltage apparatus, the gas insulated portion forming part of a switch, or of a circuit-breaker, or of a disconnector, or of a transformer, or of a surge-arresters, or of a gas-insulated line, in which each of the components comprises an end or assembly face that faces the end or assembly face of the other component, at least one of the assembly faces comprising at least one recess and wherein at least one compression sealing gasket is at least partly arranged in the at least one recess and is compressed between the assembling faces of the components, the compression sealing gasket comprising a main body of general planar extension, or extending in a plane, comprising an inner side and an outer side, and end faces, which delimit the gasket along an axis perpendicular to the plane, and connect the inner side and the outer side, made of an elastomer material, the main body having a first extension, along the axis, at least one of the inner side and the outer side being provided with a lip which has a second extension, along the axis perpendicular to the plane, less than the first extension.

2. A sealing system according to claim 1, wherein the first extension is comprised between 3 mm and 25 mm.

3. A sealing system according to claim 1, wherein the second extension is comprised between 0.5 mm and 5 mm.

4. A sealing system according to claim 1, wherein the second extension is <50% the first extension.

5. A sealing system according to claim 1, wherein the main body, respectively the lip, has a first width, respectively a second width, both widths being measured in the plane containing the axis and along an axis perpendicular to axis, such that the second width is >35% of the first width.

6. A sealing system according to claim 1, wherein the gasket has a maximum inner dimension between 50 mm and 1300 mm.

7. A sealing system according to claim 1, wherein the lip has an average compression rate higher than the main body.

8. A sealing system according to claim 1, wherein: the outer side and the inner side are parallel and/or coaxial to each other; and/or the gasket has in a plane perpendicular to the axis an annular or oval or ellipsoidal shape.

9. A sealing system according to claim 1, each of the inner side and the outer side being provided with a lip.

10. A sealing system according to claim 1, at least one of the end faces and of the outer side and the inner side has a wavy shape.

11. A sealing system according to claim 1, the lip having a side, perpendicular to the axis, extending in a same plane as one of the end faces.

12. A compression sealing gasket system according to claim 1, comprising a second sealing gasket, the second sealing gasket comprising a main body of general planar extension, or extending in a plane, comprising an inner side and an outer side, and end faces, which delimit the gasket along an axis perpendicular to the plane, and connect the inner side and the outer side, made of an elastomer material, the main body having a first extension, along the axis, at least one of the inner side and the outer side being provided with a lip which has a second extension, along the axis perpendicular to the plane, less than the first extension, the two sealing gaskets being in series, the lip of one of the gaskets being connected to the inner side or to the outer side of the other one of the gaskets.

13. A sealing system comprising two components of a gas insulated portion of a high or medium voltage apparatus, the gas insulated portion: containing, or being intended to contain, a gas comprising at least: heptafluoroisobutyronitrile and/or heptafluoroisopropyl trifluoromethyl ketone (also named 2butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-(CAS No 756-12-7)), possibly mixed with a gas or a dilution gas comprising at least CO.sub.2 and/or O.sub.2 and/or N.sub.2 and/or an oxygenated compound; or to a gas comprising at least CO.sub.2 and/or O.sub.2 and/or N.sub.2 and/or an oxygenated compound and/or water vapor; and/or the gas insulated portion being surrounded, or being intended to be surrounded by an atmosphere containing some water and/or water vapor; in which each of the components comprises an end or assembly face that faces the end or assembly face of the other component, at least one of the assembly faces comprising at least one recess and wherein at least one compression sealing gasket is at least partly arranged in the at least one recess and is compressed between the assembling faces of the components, the compression sealing gasket comprising a main body of general planar extension, or extending in a plane, comprising an inner side and an outer side, and end faces, which delimit the gasket along an axis perpendicular to the plane, and connect the inner side and the outer side, made of an elastomer material, the main body having a first extension, along the axis, at least one of the inner side and the outer side being provided with a lip which has a second extension, along the axis perpendicular to the plane, less than the first extension.

14. A method for insulating a gas insulated portion of a high or medium voltage apparatus, the portion: containing a gas comprising at least: heptafluoroisobutyronitrile and/or heptafluoroisopropyl trifluoromethyl ketone (also named 2butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-(CAS No 756-12-7)), possibly mixed with a gas or a dilution gas comprising at least CO.sub.2 and/or O.sub.2 and/or N.sub.2 and/or an oxygenated compound; or to a gas comprising at least CO.sub.2 and/or O.sub.2 and/or N.sub.2 and/or an oxygenated compound and/or water vapor; and/or the gas insulated portion being surrounded, or being intended to be surrounded, by an atmosphere containing some water and/or water vapor; the gas insulated portion comprising a sealing system according to claim 1.

15. A method according to claim 14, wherein the gas is contained in the apparatus at a pressure between 1 bar and 20 bar.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is a schematic diagram of a high voltage apparatus comprising two components assembled together using a gasket according to the invention.

(2) FIG. 2 a detail of the assembly of the components of FIG. 1 showing how a gasket according to the invention is received between the two components.

(3) FIGS. 3A, 3B and 4A shows embodiments of a gasket according to the invention.

(4) FIG. 4B shows a gasket according to the prior art.

(5) FIG. 5 shows another embodiment a gasket according to the invention.

(6) FIGS. 6A and 6B show further embodiments of a gasket according to the invention.

(7) FIGS. 7A-7B are front views of various embodiments of gaskets according to the invention.

(8) FIGS. 8A-8B show embodiments of gaskets according to the invention in the case of a system using a single recess.

(9) FIGS. 9A-9C show further embodiments of gaskets according to the invention in the case of a system using a radial recess instead of an axial one.

(10) FIG. 10 is a schematic diagram of a high voltage apparatus comprising a hole of a gas compartment closed by a flange and comprising a gasket according to the invention.

(11) FIGS. 11A and 11B show alternative shapes of the lip(s).

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

(12) FIG. 1 illustrates an example of a system according to the invention to which a gasket or a compression sealing gasket or a sealing gasket or a sealing gasket system or a sealing system or a compression sealing gasket system according to the invention can apply. It comprises a portion of a high voltage apparatus comprising components 10, 10 assembled one to the other. Here, each component 10, 10 is represented as a cylindrical and tubular component and extends coaxial to a main axis AA of the high voltage apparatus. It will be understood that the two components may be of any other shape; for example, they may be non-cylindrical tubular parts.

(13) Alternatively, one of the components, or both of them, may be a non-tubular part, for example a hole 100 of a gas compartment (FIG. 9) closed by a flange 101.

(14) Alternatively, a gasket or a compression sealing gasket or a sealing gasket or a sealing gasket system or a sealing system or a compression sealing gasket system according to the invention can be used for example at the interface between two flanges. The following description is made with reference to tubular elements, but the invention applies to any other pair of elements, the interface of which must be sealed, in particular to: a gas like heptafluoroisobutyronitrile and/or heptafluoroisopropyl trifluoromethyl ketone (also named 2-butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-(CAS No 756-12-7)), possibly mixed with a gas or a dilution gas comprising at least CO.sub.2 and/O.sub.2 and/or N.sub.2 and/or and/or an oxygenated compound; or to a gas comprising at least CO.sub.2 and/O.sub.2 and/or N.sub.2 and/or an oxygenated compound, and/or water vapor; and/or to incoming water and/or incoming water vapor, said interface being surrounded, or being intended to be surrounded, by an outer atmosphere containing some water and/or water vapor.

(15) Said gas can have a pressure (P2) between 1 bar and 20 bar, for example 5 bar or 15 bar.

(16) As can be seen in more details in FIG. 2, each component 10 comprises an end (or assembly) face 12 which faces, and possibly is connected, to the end (or assembly) face 12 of the other component 10.

(17) A gasket or a sealing system or a compression sealing gasket or a sealing gasket or a sealing gasket system or a compression sealing gasket system for connecting the components 10, 10 comprises a gasket or a sealing gasket or a compression sealing gasket or a sealing system 14 (a gasket or a sealing gasket or sealing system in the rest of this description) that is arranged axially between the faces 12, 12 of the two components 10, 10 (or, in the example of FIG. 9, between the hole 100 and the flange 101). The sealing gasket 14 extends substantially in a plane, which is perpendicular to axis AA. In this example, and in some of the examples below, the sealing gasket has a circular symmetry around axis AA.

(18) The sealing gasket or system comprises tightening means 30, for example bolts and nuts or bolting means that press axially one component 10 towards the other 10.

(19) The tightening means 30 also compress axially the sealing gasket 14 to provide a gastight connection between the two components 10, 10.

(20) According to the embodiment represented on FIG. 2, the face 12, 12 of each component 10, 10 comprises an annular recess 16, 16 in which at least part of the sealing gasket 14, 14 is received.

(21) The combined axial depth of the recesses 16 and 16 is inferior to the height or the axial height of the gasket 14 before the two components 10, 10 are assembled (said height or axial height is measured along axis AA or along an axis perpendicular to the plane in which the gasket extends). If there is only one recess, for example recess 16, then its axial depth is inferior to the axial height of the gasket 14 before the two components 10, 10 are assembled.

(22) The compression of the gasket 14 by the tightening means 30 produces an axial deformation of the gasket 14 and maintains a pressure of the gasket 14 on the bottom of each recess 16, 16.

(23) As can be seen from FIGS. 3A, 3B and 4A, the gasket 14 comprises a main body 14.sub.1 made for example of a single material, for example of an elastomer like, as non-limiting examples, unmodified butyl rubber or modified butyl rubber, for example chlorobutyl (CIIR) or bromobutyl (BIIR) rubber.

(24) The permeability of this elastomer with respect to the gas intended to fill the components 10, 10 results in a loss of gas during time.

(25) As can be seen on FIGS. 3A, 3B and 4A, a section of the main body 14.sub.1 of the gasket 14, along an axial plane containing main axis AA', can have a general rectangular shape.

(26) The main body 14.sub.1 of the gasket 14 comprises a radially outer side 20, a radially inner side 22 and two planar end faces 24, 26 that axially delimit the gasket 14 and connect the inner side 22 to the outer side 20.

(27) One or more of the sides 20, 22, 24, 26 of the main body can be wave shaped to enhance the sealing. A wave shape comprises (see FIG. 4A) at least one protuberance or peak 24a and at least one recess or depression or valley 24b, 24c. The gas pressure has a positive effect thanks to this complex shape by creating the forces that increase the contact pressure of the gasket onto the surfaces of the recesses 16 and 16. Alternatively, the sides and/or the end faces can have a different shape, or be rectilinear, as illustrated on FIG. 5 (see sides 30, 32 or end faces 34, 36).

(28) In order to reduce the permeability of the gasket 14 to: a gas like heptafluoroisobutyronitrile and/or heptafluoroisopropyl trifluoromethyl ketone (also named 2-butanone, 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-(CAS No 756-12-7)), possibly mixed with a gas or a dilution gas comprising at least CO.sub.2 and/O.sub.2 and/or N.sub.2 and/or water vapor and/or an oxygenated compound; or to a gas comprising at least CO.sub.2 and/O.sub.2 and/or N.sub.2 and/or an oxygenated compound, and/or water vapor, and/or to incoming water and/or incoming water vapor, said interface or said system being surrounded, or being intended to be surrounded, by an outer atmosphere containing some water and/or water vapor, at least one (or both) of the outer side 20 and the inner side 22 comprises a lip 14: (an inner lip on the example of FIG. 3A) which can have a substantially rectangular in a plane containing the axis AA (as can be seen on FIGS. 3A, 3B, 4A and 5; other shapes are possible, for example at least partly rounded or at least partly circular or semi-circular, as can be seen on FIGS. 11A and 11B). Preferably, the lip(s) and the main body have the same composition (see the above examples of materials of the main body, the lip(s) preferably being made of the same material as the main body), the composition of the gasket being thus homogeneous.

(29) Said inner lip has an extension (or thickness) l.sub.14 measured along an axis parallel to the AA axis less than the extension (or thickness) L.sub.14 of the main body along the same axis, for example less than or equal to 50% of said extension (or thickness) L.sub.14. The smaller the extension (or thickness) l.sub.14 (or cross-section), the better the efficiency.

(30) For example: the extension (or thickness) L.sub.14 of the main body is between 3 mm and 25 mm and the extension (or thickness) l.sub.14 (<L.sub.14) of the lip is between 0.5 mm and 5 mm.

(31) The lip 14.sub.2 offers a smaller surface area S.sub.2 to gas (in particular from the above-mentioned list) permeating in a direction perpendicular to axis AA and/or to incoming water and/or water vapor than the surface area S.sub.1 of the inner side 22 and/or the outer side 21 of a known gasket (FIG. 4B) not having a lip 14.sub.2.

(32) Permeation (molecules going through the gasket) is linked to the surface area under pressure: due to its smaller extension l.sub.14 along the axis AA the lip 14.sub.2 offers a reduced surface area S.sub.2 to permeation.

(33) In the embodiments of FIGS. 3A and 4A, the lip is an inner lip, oriented towards the part of the device having the highest pressure P2 in service conditions (the outside pressure of the device being P1<P2).

(34) In other embodiments, as on FIG. 3B for example, the lip is an outer lip, oriented towards the outside part of the device, having the lowest pressure P1 in service conditions. A gasket provided with an outer lip as on FIG. 3B is particularly efficient to limit or to prevent water and/or water vapor permeation of H.sub.2O from outside the device provided with said gasket and is also efficient against gas (in particular from the above-mentioned list) permeating in a direction perpendicular to axis AA.

(35) Temporary inversion of the pressure difference direction is permitted by the design of the invention but preferably at a lower amplitude ((P1P2)<2 bar). Preferably, the device is able to withstand vacuum (0 bar absolute inside (P2) and 1 bar absolute outside (P1)) before filling.

(36) The width w (the path of the gas through the gasket) of the gasket is measured in the plane containing the AA axis, along an axis perpendicular to AA; it is for example between 4 and 10 mm or 40 mm.

(37) In any embodiment according to the invention, the width w=w.sub.141+w.sub.142, w.sub.141 (respectively w.sub.142) is the width of the main body 14.sub.1 (respectively the width of the lip 14.sub.2), w.sub.141 and w.sub.142 (for example w.sub.141w.sub.142) are both measured in the plane containing the AA axis but along an axis perpendicular to AA. Preferably: w.sub.14235% w.sub.141 or w.sub.141w.sub.14235% w.sub.141 (the longer path of the gas through the gasket, the better the efficiency of the gasket).

(38) The main body 14.sub.1 performs several functions: it is adapted to maintain a sufficient pressure on the surfaces to ensure tightness with consideration of thermal dilatations, ageing, manufacturing tolerances and environmental constraints. It also permits easier handling of the gasket during the assembly process.

(39) Preferably, the inner or outer lip 14.sub.2 usually has an average compression rate (for example between 15% and 40%) which is higher than the average compression rate of the main body 14.sub.1 (for example between 10% and 25%). The respective recesses 16.sub.1, 16.sub.2 are preferably designed so that the lip is more compressed than the main body of the gasket. This ensures sufficient compression, preferably in all conditions and regarding the above-mentioned constraints. It can be noted that in the main body those portions A.sub.1 (see FIG. 4A) having restrictions due to the recesses 24b, 24c have a smaller compression rate than the largest portions A.sub.2.

(40) The recess for a gasket according to the invention has: a first large parallelepipedal shape (for the main body of the gasket) having an extension (or thickness) L.sub.16 measured along an axis parallel to the axis AA; and a second smaller parallelepipedal shape which has an extension (or thickness) l.sub.16, also measured along an axis parallel to the AA, l.sub.16

(41) Preferably the ratio l.sub.16/l.sub.14 is between 0.60 and 0.85 and/or the ratio L.sub.16/L.sub.14 is between 0.75 and 0.9; Generally, a ratio l.sub.16/l.sub.14

(42) FIGS. 6A and 6B show particular embodiments of a gasket or a gasket system according to the invention, comprising two gaskets according to the invention in series: a first (outer) gasket, which has (FIGS. 6A and 6b) a main body 14a (having an extension or thickness L.sub.14 and a width w.sub.141) and an inner lip 14a (having an extension or thickness l.sub.14 and a width w.sub.142) or (FIG. 6B) a main body 14a (having an extension or thickness L.sub.14 and a width w.sub.141), an outer lip 14a.sub.1 (having an extension or thickness l.sub.141 and a width W.sub.142) and an inner lip 14a (having an extension or thickness l.sub.14 and a width w.sub.142); and a second (inner) gasket (FIGS. 6A and 6b), which has a main body 14b (having an extension or thickness L.sub.14 and a width w.sub.141) and an inner lip 14b (having an extension or thickness l.sub.14 and a width w.sub.142a), the inner lip 14a of the first (outer) gasket being connected to the outer side of the main body 14b of the second (inner) gasket.

(43) In both embodiments of FIGS. 6A and 6B, the inner gasket is on the side of the device having the highest pressure P2 in service conditions (the outside pressure of the device being P1<P2).

(44) The first (outer) gasket has a lateral extension (D.sub.14a on FIG. 6A, D.sub.14a on FIG. 6B) which is larger than the second (inner) gasket (D.sub.14b on both FIGS. 6A and 6B).

(45) These 2 gaskets are adapted to corresponding double recesses 16a, 16b, 16a, 16b as shown on FIGS. 6A and 6B.

(46) The double structure of the gaskets or gasket systems of FIGS. 6A and 6B ensures a very high tightness with respect to the gases located on the pressure side of the device (at pressure P2>P1).

(47) Each of the extensions or thicknesses L.sub.14, l.sub.14, L.sub.14, l.sub.14, l.sub.141 is measured along an axis parallel to the AA axis.

(48) Each of l.sub.14 and l.sub.141 is less than the extension (or thickness) L.sub.14, for example less than 50% of said extension (or thickness) L.sub.14.

(49) l.sub.14 is less than the extension (or thickness) L.sub.14, for example less than 50% of said extension (or thickness) L.sub.14.

(50) Preferably: l.sub.14=l.sub.141=l.sub.14 and/or L.sub.14=L.sub.14.

(51) The above considerations about the widths of the main body and the width of the lip(s) may apply to the embodiments of FIG. 6A or 6B; preferably: w.sub.14235% w.sub.141 or w.sub.14235% w.sub.141; or w.sub.141w.sub.14235% w.sub.141 or w.sub.141w.sub.14235% w.sub.141 or w.sub.142+w.sub.14235% w.sub.141 or w.sub.141w.sub.142+w.sub.14235% w.sub.141; and/or: w.sub.142a35% w.sub.141, or w.sub.141w.sub.142a35% w.sub.141.

(52) FIG. 7A is a front view in a plane perpendicular to the axis (AA) (or a view in the plane of the gasket) of a circular or annular gasket or gasket system according to the invention. It has an inner diameter D.sub.1 (the inner diameter if the lip 14.sub.1) which can for example be comprised between, on the one hand, 40 mm or 50 mm or 100 mm and, on the other hand, 500 mm or even 1300 mm. Such large gaskets are more critical in terms of tightness than the usual smaller gasket (of diameter comprised between 10 mm and 40 mm).

(53) Alternatively, a gasket or a gasket system according to the invention can have in a plane perpendicular to the axis (AA) (or in the plane of the gasket) an elongated or oval or ellipsoidal shape (FIG. 7B), having a maximal inner dimension D.sub.2 which can for example be comprised between, on the one hand, 40 mm or 50 mm or 100 mm and, on the other hand, 500 mm or even 1300 mm.

(54) In general (for any of the embodiments of a gasket or of a gasket system according to the invention): the lip extends along the whole length of the inner or outer side (or the whole inner or outer periphery) of the main body of the gasket; and/or the lip is made of the same material as the main body.

(55) Variants of the invention are shown on FIGS. 8A, 9A and 9B, at the interface between two parts 10, 10: these gaskets have a L shape, the lip 14.sub.2 having a face 140, perpendicular to said AA axis, extending in a same plane as one of the lateral end faces 24, 26 of the main body 14.sub.2 of the gasket.

(56) FIG. 8B shows the gasket of FIG. 8A in a corresponding recess having an L shape. In the embodiment of FIG. 8B, only one of the two parts 10, 10 has a recess.

(57) In the embodiment of FIG. 9C, only the main body of the gasket, or part of said main body, of FIG. 9A or 9B is in a recess. As can be seen on this figure, the assembling faces of the two parts or of the two components are not contacting each other at least in an area surrounding the recess and/or the gasket (unlike the other FIGS. 2, 3A, 3B, 6A, 6B). More generally (the gasket having an <<L>> shape or any other shape), at least in an area surrounding the recess and/or the gasket, at least part of the end or assembly faces of the two components: may be contacting each other; or may not be contacting each other; in this last case, part of the gasket, for example one or more lip(s) or at least part of one or more lip(s), may not be in a recess, but may be for example between said assembling faces.

(58) These embodiment of FIGS. 8A, 8B, 9A-9C can be adapted to smaller gaskets, for example having an inner dimension or diameter of between 40 mm (or 50 mm) and 200 mm with a more compact implementation than the previously presented embodiments. They are able to replace O-rings and are easier to integrate than the gaskets described above in connection with the preceding figures.

(59) As illustrated on FIGS. 9A-9C, the main body of a gasket according to the invention can have an extension (or thickness or axial height) L.sub.14 of the main body which is larger than the distance between its inner side 22 and its outer side 20 (measured in a plane perpendicular to the axis AA or in the plane of the gasket). This applies to an L shaped gasket, but also to any other embodiment.

(60) A gasket according to the invention can be formed by injection of a non-vulcanized (or uncured) material into a mold, followed by a compression step.

(61) The invention applies for example to a switch, or to a circuit-breaker, or to a disconnector, or to a transformer, or to a surge-arresters, or to a gas-insulated line.