Dynamic sealing system comprising a sealing segment associated with an O-ring

Abstract

A dynamic sealing system comprising a central portion (20) with an external surface (20A) having a first annular groove (202) housing a sealing segment (210) made of a first material, and a peripheral portion (22) with an internal surface (22A) having a second annular groove (212) housing an O-ring (220) made of a second material, interposed between a base (216) of the second annular groove (212) and the sealing segment (210). The second material has a lower hardness than the first material. The sealing segment (210) has a greater flexural stiffness than the O-ring (220). The O-ring (220) ensures static contact between the sealing segment (210) and the peripheral portion (22). The sealing segment (210) has a dynamic sealing face (210D) vis-à-vis a flank (204B) of the first annular groove (202).Using different materials to ensure static and dynamic contact respectively allows for the optimization of each of these contacts. Figure for the abbreviation: Figure 1.

Description

Title of the invention: Dynamic sealing system comprising a sealing segment associated with an O-ring technical field

[0001] The present invention relates to the field of dynamic sealing between two concentric surfaces of revolution rotating relative to each other, and more particularly to a dynamic sealing system in which the seal between two such surfaces is achieved by means of one or more sealing segments. The invention also relates to a method for implementing such a system.

[0002] The invention is the result of technological research conducted by the Applicant, aimed at significantly improving aircraft performance and, in this sense, contributing to the reduction of their environmental impact. Prior art

[0003] Several types of solutions are known to ensure sealing, with respect to a fluid such as oil, between two concentric surfaces of revolution of two parts or structures rotating relative to each other.

[0004] Among these solutions, seals of the type known as "segment seals," or "piston rings" in English, are valued for their small size and their effectiveness even under high fluid pressures (greater than 10 bar, for example). Pressures exceeding 100 bar are encountered, for example, in devices designed to transfer a fluid (such as oil) between two reference frames rotating relative to each other, for the purpose of actuation of a variable pitch system for blades or vanes in an aircraft engine.

[0005] Such a sealing segment generally consists of a split ring-shaped metal body that can be temporarily deformed by spreading its ends apart, for placement in an annular groove formed on one of the two concentric surfaces. The ends of the segment are generally shaped to ensure a seal between them, for example by various types of circumferential overlaps, or to provide controlled clearance when the segment is in place within the annular groove.

[0006] With such a seal, the sealing between the two concentric surfaces is ensured, on the one hand, by a static radial contact between a radially external or radially internal surface of the body and the second of the two concentric surfaces, and by an axial dynamic contact between an axial end surface of the body and a corresponding flank of the annular groove. By "static contact," it is necessary to understand A contact between two static elements relative to each other, in this case the body of the segment and the second surface, is defined as a contact with friction between two elements in rotational motion relative to each other, in this case the body and the flank of the annular groove. In practice, after a break-in period, friction at the dynamic contact is reduced by means of a controlled or calibrated fluid leakage rate, accompanied by hydrodynamic effects between the two surfaces involved in the dynamic contact.

[0007] The quality of the radial static contact is a key parameter for limiting and / or controlling fluid leakage at the sealing segment, particularly in the presence of a strong pressure differential on either side of the seal.

[0008] This quality of the static radial contact is generally limited by deformations likely to affect one or the other of the concentric surfaces, such deformations being able in particular to be caused by centrifugal force or thermal expansions and thermomechanical deformations.

[0009] However, calculations show that the appearance of radial play at the static contact has a cube-shaped influence on the leakage rate.

[0010] There is therefore a need to improve the way in which sealing is achieved between concentric surfaces rotating relative to each other by means of sealing segments. Description of the invention

[0011] To address this need, the invention proposes a dynamic sealing system comprising: • a central part presenting an external surface with a geometry of revolution about an axis; • a peripheral part having an internal surface with a geometry of revolution around the axis arranged around the external surface of the central part with the ability to rotate relative to the latter around the axis; • an annular space defined between the external and internal surfaces to contain a fluid; • at least one sealing device to confine the fluid in at least one annular region within the annular space; • for the sealing device or for each sealing device: a first annular groove formed in a first of the respective external and internal surfaces of the central and peripheral parts and having two respective opposite sides connected to each other by a respective bottom, and a second annular groove formed in a second of the respective external and internal surfaces of the central and peripheral parts, opposite the first annular groove, and presenting two respective opposite flanks connected to each other by a respective bottom.

[0012] The sealing device or each sealing device comprises: • a split ring-shaped sealing segment, made of a first material, mounted in the first annular groove, and having a radially internal surface, a radially external surface, and a dynamic sealing face with respect to one of the flanks of the first annular groove; and • an O-ring, made of a second material, interposed between that of the radially external and radially internal surfaces of the sealing segment which is located on the opposite side to the bottom of the first annular groove, and the bottom of the second annular groove, so that the O-ring is in static contact both with the bottom of the second annular groove and with that of the radially external and radially internal surfaces of the sealing segment which is located on the opposite side to the bottom of the first annular groove, the O-ring thus ensuring static contact of the sealing device on said second of the respective external and internal surfaces of the central and peripheral parts all around the axis.

[0013] The other of the radially external and radially internal surfaces of the sealing segment is arranged opposite - and spaced - from the bottom of the first annular groove.

[0014] The first material is chosen so that the sealing segment has a flexural stiffness greater than that of the O-ring, and the second material has a hardness less than that of the first material.

[0015] The use of different materials to ensure static contact and dynamic contact respectively allows each of these contacts to be optimized.

[0016] In particular, the interposition of the O-ring, in a material of less hardness, makes it possible to considerably improve the sealing at the level of the static radial contact between the sealing device and the aforementioned second surface, by promoting the penetration of roughnesses of the second surface into the O-ring, and by improving the rotational bonding of the sealing segment with the second surface (via the O-ring).

[0017] With regard to the sealing segment, the choice of a harder material, and giving the sealing segment a stiffness greater than that of the O-ring, makes it possible to optimize the axial dynamic contact between the sealing segment and the corresponding flank of the first annular groove, to guarantee an optimal geometry for the sealing segment, and to ensure that the sealing segment forces the O-ring against the second surface.

[0018] In preferred embodiments of the invention, the system includes a chamfer formed at the junction between said first of the respective external and internal surfaces of the central and peripheral parts, and at least one of the flanks of the first annular groove.

[0019] In preferred embodiments of the invention, the first material is chosen from metals, metal alloys, polymers, self-lubricating plastics, graphite and composite materials.

[0020] In preferred embodiments of the invention, the second material is an elastomer.

[0021] In preferred embodiments of the invention, the system is configured for the transfer of multiple fluid paths between fluidic inlets and fluidic outlets.

[0022] The system preferably comprises transfer chambers defined as annular portions of said annular space, each between two said sealing devices.

[0023] The central part preferably defines first fluidic paths connecting respectively the fluidic inlets of the system to the transfer chambers through said external surface.

[0024] The peripheral part preferably defines second fluidic paths connecting respectively the fluidic outlets of the system to the transfer chambers through said internal surface.

[0025] In preferred embodiments of the invention, the sealing segment is mounted in a piston configuration, whereby: • said first surface is the external surface of the central part; • said second surface is the internal surface of the peripheral part; and • said surface of the sealing segment with which the O-ring is in static contact is the radially external surface of the sealing segment.

[0026] Preferably, the sealing segment has a radius of curvature in the free state greater than a radius of curvature that it has within the system, so that within the system, the sealing segment undergoes a bending deformation stress and consequently tends to stress the O-ring against the second of said respective external and internal surfaces of the central and peripheral parts.

[0027] The invention also relates to an aircraft turbomachine, comprising at least one system of the type defined above, and comprising a stator attached to one of the central and peripheral parts of the system and a rotor attached to the other central or peripheral part of the system.

[0028] The invention also relates to a method for implementing a system of the type defined above, comprising: • the rotation of at least one of the central and peripheral parts relative to the other; • the supply of a fluid to the annular space; and • the circumscription of the fluid in said annular region of the annular space by means of the sealing device.

[0029] In this method, a static contact of the O-ring with the bottom of the second annular groove and with that among the radially external and radially internal surfaces of the sealing segment which is located on the opposite side to the bottom of the first annular groove, secures the rotating sealing segment with said second surface, while a dynamic seal is implemented between said dynamic sealing face of the sealing segment and said flank of the first annular groove. Brief description of the drawings

[0030] The invention will be better understood, and other details, advantages and features thereof will become apparent from the following description, given by way of non-limiting example and with reference to the accompanying drawings in which:

[0031] [Fig-1] is a partial schematic half-view in axial section of a system comprising a segment and O-ring sealing device, according to an embodiment of the invention;

[0032] [Fig.2] is a schematic cross-sectional view of the sealing segment, in a service configuration (solid line) and in a rest configuration (dashed line);

[0033] [Fig.3] is a view of a part of [Fig.1] to scale of the roughness and defects of surface, illustrating a region of radial static contact within the system;

[0034] [Fig.4] is a view similar to [Fig.1], illustrating the operation of the system;

[0035] [Fig.5] is a view similar to [Fig.1], illustrating a system comprising a segment and O-ring sealing device, according to another embodiment of the invention;

[0036] [Fig.6] is a view similar to [Fig.1], illustrating a system comprising a segment and O-ring sealing device, according to another embodiment of the invention;

[0037] [Fig.7] is a view similar to [Fig.1], illustrating a system comprising a segment and O-ring sealing device, according to another embodiment of the invention;

[0038] [Fig.8] is a schematic axial cross-sectional view of a system such as that of the [Fig.l], configured as a multi-way fluid transfer system for aircraft turbomachinery;

[0039] [Fig.9] is a schematic axial cross-sectional view of a turbomachine comprising a system such as that of [Fig.1].

[0040] Throughout these figures, identical references may designate identical or analogous elements. Detailed presentation of preferred embodiments I. General Application

[0041] Figure 1 illustrates a dynamically sealing system 10, comprising a central part 20 and a peripheral part 22, shown schematically. Each of these parts can be a single piece or an assembly of parts. A particular example will be described in more detail below with reference to Figure 8.

[0042] Still with reference to [Fig.1], the central part 20 has an external surface 20A with a geometry of revolution about an axis 8. The peripheral part 22 has an internal surface 22A with a geometry of revolution about the axis 8, arranged around the external surface 20A of the central part 20, with the ability to rotate relative to the latter about the axis 8.

[0043] In the following description, the axial direction X is the direction of axis 8. The radial direction R is at every point a direction orthogonal to and passing through axis 8, and the orthoradial or circumferential direction C is at every point a direction orthogonal to the radial direction R and to axis 8. A transverse plane is a plane orthogonal to axis 8. Unless otherwise indicated, the terms "internal" and "external" refer respectively to a relative proximity and a relative distance of an element from axis 8. Furthermore, the term "axial" is used with reference to axis 8.

[0044] An annular space 23 is generally defined between the external surface 20A and the internal surface 22A to contain a fluid, for example, to allow the circulation of a pressurized fluid through the annular space. The system generally comprises means such as channels or conduits for supplying such a fluid to the annular space 23.

[0045] To confine the fluid within at least one annular region 23A within the annular space 23 (for example on the left in [Fig.1]), the system 10 includes at least one sealing device 200. Of course, several such devices 200 can be provided to delimit the two axial sides of an annular region within the annular space 23, or to divide the annular space 23 into several annular regions separated from each other in a sealed manner, as will become clearer in what follows.

[0046] For the device 200 (or each device 200), a first annular groove 202 is formed in a first of the external surfaces 20A of the central part 20 and internal 22A of the peripheral part 22, in this case in the external surface 20A. This first annular groove 202 has two opposing flanks 204A, 204B connected to each other by a bottom 206. The two flanks 204A, 204B extend preferentially along the radial direction R, while the bottom 206 is preferentially cylindrical in shape along the axis 8.

[0047] The device 200 further includes a sealing segment 210 mounted in the first annular groove 202. The sealing segment 210 is in the form of a split ring, in a manner analogous to known types of sealing segments, and has a radially internal surface 210A and a radially external surface 210B connected to each other by a first flank 210C and a second flank 210D opposite (or axial end surfaces) respectively arranged opposite the flanks 204A, 204B of the first annular groove 202.

[0048] The sealing is intended to be achieved by a static radial contact between the second of the external surfaces 20A of the central part 20 and internal 22A of the peripheral part 22, in this case the internal surface 22A, and the sealing device 200, and by an axial dynamic contact between one of the flanks 204B of the first annular groove 202 and one of the corresponding flanks 210D of the sealing segment 210.

[0049] The example described corresponds to a configuration commonly referred to as a "piston" type configuration, in which the first annular groove 202 is formed in the external surface 20A of the central part 20 as indicated above and the radial static contact is provided to occur between a radially external surface of the sealing device 200 and the internal surface 22A of the peripheral part 22. This example is nevertheless transposable to a "rod" type configuration, that is to say a configuration in which the first annular groove is formed in the internal surface 22A of the peripheral part 22, and in which the radial static contact is provided to occur between a radially internal surface of the sealing device 200 and the external surface 20A of the central part 20.

[0050] According to a particular feature of the invention, for the device 200 (or each device 200), a second annular groove 212 is formed in the second of the external surfaces 20A of the central part 20 and internal 22A of the peripheral part 22, in this case in the internal surface 22A, opposite the first annular groove 202.

[0051] The second annular groove 212 has two opposite sides 214A, 214B connected to each other by a bottom 216. The two sides 214A, 214B extend preferentially along the radial direction R, while the bottom 216 is preferably cylindrical in shape along the axis 8.

[0052] Furthermore, the sealing device 200 further comprises an O-ring 220 interposed between the bottom 216 of the second annular groove 212 and the radially external surface 210B of the sealing segment 210, so that the radial static contact The aforementioned connection between the internal surface 22A (or more generally the second of the external surfaces 20A of the central part 20 and internal 22A of the peripheral part 22) and the sealing device 200 is made via the O-ring 220.

[0053] The sealing segment 210 is made of a first material, preferably a metal or a metal alloy, generally chosen so that the sealing segment 210 has a flexural stiffness greater than that of the O-ring 220.

[0054] The O-ring 220 covers over 360 degrees one of the radially external surfaces 210B and radially internal surfaces 210A of the sealing segment 210, in this case the radially external surface 210B.

[0055] The O-ring 220 is made of a second material, having a lower hardness than the first material. The hardness of the two materials can be compared by any penetration or rebound test method. The second material is preferably an elastomer, for example of the FKM (fluoroelastomer), FFKM (perfluoroelastomer), NBR (acrylonitrile butadiene rubber), HNBR (hydrogenated nitrile, also known as HSN) type, or a PTFE (polytetrafluoroethylene) based elastomer.

[0056] The sealing segment 210 is configured such that its retention within the first annular groove 202 results in a stress tending to open the split ring formed by this sealing segment 210, that is, tending to spread its ends apart by increasing the radius of curvature of the sealing segment 210, which has the effect of applying the O-ring 220 against the bottom 216 of the second annular groove 212. To this end, the sealing segment 210 is such that, at rest, as illustrated by the dashed line in [Fig. 2], the sealing segment 210 adopts a configuration in which its ends 222A, 222B are further apart than in the service configuration of the sealing segment 210, that is, the configuration in which the sealing segment 210 adopts under constraint within system 10, illustrated in continuous line on [Fig.2].

[0057] Furthermore, the ends 222A, 222B of the sealing segment 210 ([Fig.2]) are shaped to ensure a seal between them, for example by a circumferential overlap of these ends, when the sealing segment 210 is in place within the first annular groove 202.

[0058] The sealing segment 210 is further shaped so that its surface, among its radially internal surfaces 210A and radially external surfaces 210B, which is not the one in contact with the O-ring 220, in this case its radially internal surface 210A, is spaced from the bottom 206 of the first annular groove 202 which is opposite this surface 210A (see [Fig. 1]).

[0059] The stiffness of the sealing segment 210 thus contributes to maintaining the O-ring 220 in close contact, on one side with the bottom 216 of the second annular groove 212, and on the other side with the corresponding surface 210B of the sealing segment, while ensuring, due to the space present between the opposite surface 210A of the sealing segment 210 and the bottom 206 of the first annular groove 202, the absence of contact between the surface 21 OA of the sealing segment 210 and the central part 20.

[0060] The O-ring 220 thus ensures the static radial contact between the sealing device 200, in particular the sealing segment 210, and the peripheral part 22.

[0061] Alternatively, in the case of a configuration reversed with respect to that described above, i.e. a "rod" type configuration, the O-ring 220 is interposed between the radially internal surface 210A of the sealing segment 210 and the latter is configured so that its retention around the external surface 20A of the central part results in a stress tending to close the split ring formed by the sealing segment 210, i.e. tending to bring the ends of the latter closer together by reducing the radius of curvature of the sealing segment 210, so as to apply the O-ring 220 against the bottom 216 of the second annular groove 212 which is then defined in the external surface 20A of the central part 20.

[0062] In all cases, under the effect of the radial force applied by the sealing segment 210 on the O-ring 220, the latter tends to deform within the second annular groove 212 as illustrated in [Fig.1], by comparison with its rest shape illustrated in dashed line and corresponding for example to a torus shape with circular cross-section.

[0063] To avoid any contact, despite such deformations, between the O-ring 220 and the central part 20 (or more generally the part including the first annular groove 202), which could impair the proper functioning of the sealing device 200, a chamfer 230 is provided at the junction between the external surface 20A of the central part and at least one of the flanks 204A of the first annular groove 202, located on the side of the annular region 23A (i.e. on the side of the highest fluid pressures within the annular space 23).

[0064] For the same purpose, the flank 214B of the second annular groove 212, located on the opposite side to the annular region 23A (i.e. located on the side of the lowest fluid pressures within the annular space 23), is preferably offset axially with respect to the corresponding flank 204B of the first annular groove 202, in the direction of the annular region 23A (and therefore in the direction of the opposite flank 204A of the first annular groove 202). In other words, the dynamic sealing interface between the sealing segment 210 and the flank 204B of the first annular groove 202 is axially offset from the static contact zone between the O-ring 220 and the flank 214B of the second annular groove 212, in a direction away from the opposite flank 214A of the second annular groove 212 (i.e. to the right, or (still towards the increasing x, on [Fig. 1]), which helps to move the O-ring 220 away from the region of the external surface 20A of the central part located near the flank 204B. Such an axial offset thus makes it possible to limit the risks of contact between the O-ring 220 and the central part 20 on the side opposite the annular region 23A.

[0065] In some cases, the aforementioned axial offset between the flanks 214B and 204B is obtained by means of an overall axial offset of the grooves 202 and 212, in which case a median transverse plane 212P of the second annular groove 212 is axially offset by a distance D in the direction of the annular region 23A (i.e. on the side of the highest fluid pressures within the annular space 23), relative to a median transverse plane 202P of the first annular groove 202.

[0066] Still with reference to [Fig.1], as explained above, one of the flanks 210D of the sealing segment 210 defines a dynamic sealing face, ensuring the axial dynamic contact between the sealing segment 210 and one of the flanks 204B of the first annular groove 202, and therefore with the central part 20.

[0067] The sealing segment 210 and the first annular groove 202 are preferably configured to obtain an elasto-hydrodynamic (“EHD”) or hydrodynamic (“HD”) lubrication regime at the level of the axial dynamic contact in operation, which makes it possible to minimize the wear of the surfaces concerned by this axial dynamic contact.

[0068] In certain cases, particularly cases where the axial dynamic contact is intended to operate in an unlubricated regime at least in certain transient phases of operation, the sealing segment 210 can be made of a self-lubricating material, for example a self-lubricating material based on PTFE, virgin or filled polyimide (PI), or graphite.

[0069] Generally, interposing an O-ring made of an elastomeric material, or more generally of a material of lesser hardness, between the sealing segment 210 and the internal surface 22A (or more generally the second surface among the external surface 20A of the central part 20 and the internal surface 22A of the peripheral part 22), makes it possible to considerably improve the sealing at the level of the radial static contact between the sealing device 200 and this surface.

[0070] Indeed, as illustrated in [Fig.3], the low hardness of the second material allows the protruding irregularities or roughness of the internal surface 22A, at the level of the bottom 216 of the second annular groove 212, to penetrate into the O-ring 220 and thus prevent any circulation of fluid between the sealing device 200 and the surface 22A.

[0071] The flexibility of the O-ring 220 also allows it to deform to conform to larger-scale shape defects and deformations of the internal surface 22A, at the level of the bottom 216 of the second annular groove 212, for example deformations caused by thermal expansions.

[0072] Furthermore, the rotational locking of the sealing segment 210 with the internal surface 22A is also improved. The coefficient of friction between the second material, constituting the O-ring 220, and the first material, constituting the sealing segment 210, is generally greater than the coefficient of friction that would be between two elements made of the first material.

[0073] The risk of radial dynamic contact being established between the sealing device 200 and the internal surface 22A, instead of static contact, is thus optimally limited. The friction induced by the dynamic contact, and therefore the resulting wear, occurs only on the dynamic sealing face defined by the flank 210D of the sealing segment 210.

[0074] Fig. 4 illustrates the operation of the system 10, in particular the path of the fluid F present in the annular region 23A, blocked by the static sealing ensured by the O-ring 220, and generally exhibiting a controlled or calibrated leakage flow LF, through the axial dynamic contact zone between the flank 210D or dynamic sealing face of the sealing segment 210 and the flank 204B of the first annular groove 202.

[0075] Furthermore, Figures 5 and 6 illustrate different possible cross-sections, as alternatives, for the O-ring 220 intended to ensure radial static contact, for example a lobed cross-section, for example a cross-section formed by four lobes 232 ([Fig. 5]), and a "D" cross-section ([Fig. 6]) having a convex or domed radially internal end 234 and a straight radially external end 236. For clarity, the O-ring 220 illustrated in Figures 5 and 6 is shown in its resting state, i.e., before being radially compressed by the sealing segment 210. The "D" cross-section ([Fig. 6]) can, in certain cases, improve contact by friction. Such a D-shaped section seal profile is also more massive and can tolerate higher static pressures in some cases, while limiting the risk of extrusion and thus limiting the need for an anti-extrusion ring.

[0076] Furthermore, with reference to [Fig. 7], the sealing device may include an anti-extrusion ring 240 with a generally triangular cross-section such that it presents a first annular surface 242 applied to the radially external surface 210B of the sealing segment 210, a second annular surface 244 applied against the flank 214B of the second annular groove 212 (i.e., the flank on the same side as the flank 204B of the first groove against which the dynamic axial contact is established), and a third annular surface 246 against which a portion of the O-ring 220 rests. Such an anti-extrusion ring 240 may be useful when the fluid pressure differential is expected on either side of the device The sealing ring 200 is likely to cause an extrusion of the O-ring 220 axially outwards from the second annular groove 212. Such an anti-extrusion ring 240 can be made of a polymer or metal and be of a type conventionally used in the context of sealing segments.

[0077] As explained above, the implementation of system 10 generally involves: • the rotation of at least one of the central parts 20 and peripheral parts 22 relative to the other; • the supply of fluid to the annular space 23; and • the circumscription of the fluid in the annular region 23A of space annular 23 by means of the sealing device 200.

[0078] Furthermore, the implementation of the system 10 is such that a static contact between the O-ring 220 and said second surface, in this case the internal surface 22A of the peripheral part 22, secures the rotating sealing segment 210 with said second surface, while a dynamic seal is implemented between said dynamic sealing face defined by the flank 210D of the sealing segment 210, and the corresponding flank 204B of the first annular groove 202. II. Specific Application

[0079] Fig. 8 illustrates a particular application of the invention, in which the system 10 is configured to transfer several fluid paths between two frames rotating relative to each other, for example between a turbomachine stator, defining a fixed frame, and a turbomachine rotor, defining a frame rotating about the axis 8. In the example described, there are three fluid paths, but the principles described below are of course applicable regardless of the number of fluid paths.

[0080] The stator includes, for example, a fluid supply structure (not shown in [Fig. 8]) having several fluid outlets, in this case three, which are connected respectively to fluid inlets 14A-14C of the system 10, while the rotor includes fluid receiving means (not shown) connected to fluid outlets 16A-16C of the device. Although the present description provides, for convenience, a direction of fluid flow from the fluid inlets to the fluid outlets through the system 10, a reverse direction of flow is possible. In this respect, the terms "inlet" and "outlet" should be considered here as synonymous with passage orifices or "fluid ports."

[0081] The system 10 of [Fig.8] generally comprises the central part 20, and the peripheral part 22 arranged around the central part 20 with the ability to rotate relative to the latter along the axis 8.

[0082] The central part 20 is, for example, intended to be integral with the stator, in this case the aforementioned fluid supply structure, while the peripheral part 22 is, for example, intended to be integral with the rotor. In other application examples, the roles of the central part 20 and the peripheral part 22 may be reversed, with the central part then being integral with a rotor and the peripheral part being integral with a stator.

[0083] The central part 20 has an external surface 20A with a geometry of revolution about axis 8, preferably cylindrical in shape. The peripheral part 22 has an internal surface 22A with a geometry of revolution about axis 8, arranged around the external surface 20A of the central part 20, and preferably with a shape broadly similar to that of the external surface 20A up to a homothetic transformation, the two surfaces possibly differing further by the presence of different annular orifices and grooves. In the illustrated embodiment, the internal surface 22A of the peripheral part 22 is defined jointly by several parts constituting the peripheral part 22, for example a receiving sleeve DR and two rings 70A, 70B mounted in the sleeve DR. Alternatively, the internal surface 22A of the peripheral part 22 may be defined by a single part.

[0084] The annular space 23 is, as in the above, defined between the external surface 20A of the central part 20 and the internal surface 22A of the peripheral part 22.

[0085] In general, the annular space 23 comprises, arranged axially in alternation, first annular regions defining transfer chambers 24A-24C, and second annular regions 26A-26D, with a restricted cross-section compared to the transfer chambers 24A-24C, to separate the latter, on the one hand, from each other, and, on the other hand, from the outside of the annular space 23.

[0086] For each of the fluid paths to be transferred, the central part 20 comprises a fluidic path in fluidic communication with a corresponding fluidic path within the peripheral part 22, in order to allow the fluid of the path in question to flow from a corresponding fluidic inlet 14A-14C integral with the central part 20, to a corresponding fluidic outlet 16A-16C integral with the peripheral part 22. Furthermore, the pairwise communication between the fluidic paths of the central part 20, referred to hereafter as the first fluidic paths and referenced FP1A-FP1C, and the fluidic paths of the peripheral part 22, referred to hereafter as the second fluidic paths and referenced FP2A-FP2C, is implemented via the transfer chambers 24A-24C, defined between the external surface 20A of the central part 20 and the internal surface 22A. of the peripheral part 22.Each first fluidic path FP1A-FP1C therefore connects a fluidic inlet 14A-14C corresponding to a transfer chamber 24A-24C. corresponding, the latter being also connected to a corresponding 16A-16C fluidic output by a second corresponding FP2A-FP2C fluidic path.

[0087] The fluidic inlets 14A-14C are defined by a longitudinal end portion of the central portion 20 located on a first axial side SI. The fluidic outlets 16A-16C can be arranged at a longitudinal end of the peripheral portion 22 located on a second axial side S2 opposite the first axial side SI and / or in an external surface 28 of the peripheral portion 22. In the illustrated example, a fluidic outlet 16A is arranged at the longitudinal end of the peripheral portion 22 on the second axial side S2, while two other fluidic outlets 16B and 16C are defined in the external surface 28 of the peripheral portion 22.

[0088] As mentioned above, the central portion 20 is configured to connect the fluidic inlets of the system 14A-14C to the transfer chambers 24A-24C, respectively, through the external surface 20A of the central portion 20, while the peripheral portion 22 is configured to connect the fluidic outlets of the system 16A-16C to the transfer chambers 24A-24C, respectively, through the internal surface 22A of the peripheral portion 22. The means for achieving such a result will not be described here and are extraneous to the invention. Examples of configurations for the central and peripheral portions are detailed in the patent application filed in France on October 20, 2023, under number FR2311395.

[0089] To connect the central part 20 and peripheral part 22 by allowing rotational guidance of one relative to the other, the system 10 includes at least one radially interposed bearing between the central part 20 and the peripheral part 22, for example two bearings 110A, 110B with rollers arranged axially on either side of the annular space 23.

[0090] The sealing between the different annular regions defined within the annular space 23 is ensured by means of sealing devices 200 of the type described above with reference to figures 1-8. Thus, a sealing device 200 is provided between one of the bearings 110A and an extreme transfer chamber 24A, another sealing device 200 is provided between the other bearing 110B and another extreme transfer chamber 24C, and two sealing devices 200 are provided on either side of an intermediate transfer chamber 24B (located between the extreme transfer chambers) so as to ensure the sealing between the transfer chambers 24A-24C.

[0091] In the context of this disclosure, the central fluidic path, connecting the fluidic inlet 14B to the fluidic outlet 16B, is intended to be supplied with a lower fluid pressure than the two other fluidic paths which respectively connect the fluidic inlet 14A to the fluidic outlet 16A and the fluidic inlet 14C at the fluidic outlet 16C. This characteristic determines where the region of highest pressure is located for each of the sealing devices 200 of the system.

[0092] A method for implementing system 10 of the type described above with reference to [Fig. 8] generally comprises: • selective fluid supply to the first fluidic paths FP1A-FP1C, via the fluidic inlets 14A-14C of the system; • the circulation of the fluid in the first fluidic paths FP1A-FP1C up to the transfer chambers 24A-24C; • the circulation of the fluid in the second fluidic paths FP2A-FP2C from the transfer chambers 24A-24C, up to the fluidic outlets 16A-16C of the system.

[0093] Fig. 9 illustrates a turbomachine 310, for example a twin-spool turbofan engine for aircraft, generally comprising a fan 312 for the intake of an airflow Fl which divides downstream of the fan into a primary flow F2 flowing in a primary flow channel, hereinafter referred to as the primary flow PV, and a secondary flow F3 flowing in a secondary flow channel, hereinafter referred to as the secondary flow SV, arranged around the primary flow PV.

[0094] The turbomachine comprises, for example, a low-pressure compressor 314, a high-pressure compressor 316, a combustion chamber 318, a high-pressure turbine 320, and a low-pressure turbine 322, which together define the primary flow PV. The respective rotors of the high-pressure compressor and the high-pressure turbine are connected by a shaft called the "high-pressure shaft," while the respective rotors of the low-pressure compressor and the low-pressure turbine are connected by a shaft called the "low-pressure shaft," in a well-known manner. These rotors are mounted to rotate about a shaft 328 of the turbomachine.

[0095] The turbomachine includes a system 10 of the type described above, with axis 8 for example coinciding with axis 328 of the turbomachine 310.

[0096] A stator 330 of the turbomachine is attached to one of the central 20 and peripheral 22 parts of the device, in this case the central part 20. A rotor 340 of the turbomachine is attached to the other part, in this case the peripheral part 22, of the device.

[0097] The system 10, illustrated very schematically in [Fig. 9], is arranged, for example, so that its fluidic outlets 16A-16C are connected to fluidic chambers of actuators carried by the aforementioned rotor 340 to allow the control of such actuators. In particular, the device is, for example, of the type commonly called OTB (“Oil Transfer Bearing”) and intended to supply a cylinder controlling the stalling blades of one or more propellers as well as a blade safety actuator.

Claims

1. Demands Dynamic sealing system, the system comprising: • a central part (20) having an external surface (20A) with a geometry of revolution about an axis (8); • a peripheral part (22) having an internal surface (22A) with a geometry of revolution about the axis (8) arranged around the external surface (20A) of the central part with the ability to rotate relative to the latter about the axis (8); • an annular space (23) defined between the external (20A) and internal (22A) surfaces to contain a fluid (F); • at least one sealing device (200) to confine the fluid (F) in at least one annular region (23A) within the annular space (23); • for the sealing device (200) or for each sealing device (200): a first annular groove (202) formed in a first of the respective external (20A) and internal (22A) surfaces of the central (20) and peripheral (22) parts and having two respective opposite flanks (204A, 204B) connected to each other by a respective bottom (206), and a second annular groove (212) formed in a second of the respective external (20A) and internal (22A) surfaces of the central (20) and peripheral (22) parts, opposite the first annular groove (202), and having two respective opposite flanks (214A, 214B) connected to each other by a respective bottom (216); the sealing device (200) or each sealing device (200) comprising: • a split ring-shaped sealing segment (210), made of a first material, mounted in the first annular groove (202), and having a radially internal surface (210A), a radially external surface (210B), and a dynamic sealing face (210D) with respect to one of the flanks (204B) of the first annular groove (202); and • an O-ring (220), made of a second material, interposed between that one of the radially external (210B) and radially internal (21 OA) surfaces of the sealing segment (210) located on the side opposite the bottom (206) of the first annular groove (202), and the bottom (216) of the second annular groove (212), such that the O-ring (220) is in static contact both with the bottom (216) of the second annular groove (212) and with that one of the radially external (210B) and radially internal (210A) surfaces of the sealing segment (210) located on the side opposite the bottom (206) of the first annular groove (202), the O-ring (220) thus ensuring static contact of the sealing device (200) with said second of the respective external (20A) and internal (22A) surfaces of the central (20) and peripheral parts (22) all around the axis (8);the other of the radially external (210B) and radially internal (210A) surfaces of the sealing segment (210) being arranged opposite - and spaced - from the bottom (206) of the first annular groove (202); the first material being chosen so that the sealing segment (210) has a flexural stiffness greater than that of the O-ring (220), and the second material having a hardness less than that of the first material.

2. System according to claim 1, comprising a chamfer (230) formed at the junction between said first of the respective external (20A) and internal (22A) surfaces of the central (20) and peripheral (22) parts, and at least one of the flanks (204A) of the first annular groove (202).

3. System according to claim 1 or 2, wherein the first material is selected from metals, metal alloys, polymers, self-lubricating plastics, graphite and composite materials.

4. System according to any one of claims 1 to 3, wherein the second material is an elastomer.

5. A system according to any one of claims 1 to 4, wherein: • Transfer chambers (24A to 24C) are defined as annular portions of said annular space (23), each between two said sealing devices (200); • The central part (20) defines first fluid paths (FP1A to FP1C) connecting respectively fluid inlets (14A to 14C) of the system to the transfer chambers (24A to 24C) through said external surface (20A); • The peripheral part (22) defines second fluid paths (FP2A to FP2C) connecting respectively fluid outlets (16A to 16C) of the system to the transfer chambers (24A to 24C) through said internal surface (22A); the system being thus configured for the transfer of several fluid paths between the fluid inlets (14A to 14C) and the fluid outlets (16A to 16C).

6. System according to any one of claims 1 to 5, wherein the sealing segment (210) is in piston mounting, wherein: • said first surface is the external surface (20A) of the central part (20); • said second surface is the internal surface (22A) of the peripheral part (22); and • said surface of the sealing segment (210) with which the O-ring (220) is in static contact is the radially external surface (210B) of the sealing segment (210).

7. System according to claim 6, wherein the sealing segment (210) has a radius of curvature in the free state greater than a radius of curvature which it has within the system (10), so that within the system, the sealing segment (210) is subjected to a bending deformation stress and consequently tends to stress the O-ring (220) against the second of said external (20A) and internal (22A) surfaces respectively of the central (20) and peripheral (22) parts.

8. Aircraft turbomachine (310), comprising at least one system (10) according to any one of claims 1 to 7, and comprising a stator integral with one of the central (20) and peripheral parts

9. (22) of the system and a rotor attached to the other central (20) or peripheral (22) part of the system. A method for implementing a system (10) according to any one of claims 1 to 7, comprising: • the rotation of at least one of the central (20) and peripheral (22) parts relative to the other; • the supply of a fluid (F) to the annular space (23); and • the circumscription of the fluid (F) in said annular region (23A) of the annular space (23) by means of the sealing device (200); in which a static contact of the O-ring (220) with the bottom (216) of the second annular groove (212) and with that among the radially external (210B) and radially internal (210A) surfaces of the sealing segment (210) which is located on the opposite side to the bottom (206) of the first annular groove (202), secures the rotating sealing segment (210) with said second surface, while a dynamic seal is implemented between said dynamic sealing face (210D) of the sealing segment (210) and said flank (204B) of the first annular groove (202).

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