Dynamic sealing system including an improved sealing segment

Abstract

Dynamic sealing system comprising a central part (20) with an external surface (20A), a peripheral part (22) with an internal surface (22A), a sealing device (200) comprising: a groove (202), and a sealing segment (210) formed by a split annular body (212), made of a first material, having a radially external surface (220), a radially internal surface (222), and a dynamic sealing face (226) opposite a flank (204B) of the groove, and a pad (214) made of a second material having a hardness greater than that of the first material, covering the surface (220) or (222) of the body to which the pad is rigidly attached, and applied against one of the external (20A) and internal (22A) surfaces so that the pad (214) ensures static contact of the sealing segment (210) against this surface. The other of the surfaces (220) and (222) of the body is opposite a bottom (206) of the throat.The body (212) has a greater flexural stiffness than the skate (214). Figure for the abbreviation: Figure 4.

Description

Title of the invention: Dynamic sealing system comprising an improved sealing segment. 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, comprising an annular groove formed in a first of the respective external and internal surfaces of the central and peripheral parts and having two opposite sides connected to each other by a bottom, and a sealing segment mounted in the annular groove;

[0012] in which the sealing segment is formed by: • a split ring-shaped body, made of a first material, and having a radially external surface, a radially internal surface, and a dynamic sealing face with respect to one of the flanks of the annular groove; and • a pad, made of a second material, covering one of the radially external and radially internal surfaces of the body to which the pad is rigidly attached, and applied against a second of said respective external and internal surfaces of the central and peripheral parts, so that the pad ensures static contact of the sealing segment on said second surface all around the axis;

[0013] the other of the radially external and radially internal surfaces of the body being arranged opposite - and spaced - from the bottom of the annular groove;

[0014] the first material being chosen so that the body has a flexural stiffness greater than that of the skate, and the second material having 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 choice of a less hard material to constitute the pad makes it possible to considerably improve the sealing at the level of the static radial contact between the sealing segment and the aforementioned second surface, by promoting the penetration of roughnesses of the second surface into the pad, and by improving the rotational bonding of the sealing segment with the second surface.

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

[0018] In preferred embodiments of the invention, the body has a shoulder extending outward from said surface of the body covered by the pad, and thus forming a stop against an axial displacement of the pad in a first axial direction.

[0019] In preferred embodiments of the invention, said shoulder is a first shoulder, and the body has a second shoulder extending outward from said surface of the body covered by the pad and forming a stop against an axial displacement of the pad in a second axial direction opposite to the first axial direction, the pad being interposed axially between the first shoulder and the second shoulder.

[0020] In preferred embodiments of the invention, the first material is chosen from metals, metal alloys, self-lubricating plastics, graphite and composite materials.

[0021] In preferred embodiments of the invention, the second material is an elastomer.

[0022] In preferred embodiments of the invention, transfer chambers are defined as annular portions of said annular space, each between two said sealing devices, the central part defines first fluidic paths connecting respectively fluidic inlets of the system to the transfer chambers through said external surface, and the peripheral part defines second fluidic paths connecting respectively fluidic outlets of the system to the transfer chambers through said internal surface, the system being thus configured for the transfer of several fluid paths between the fluidic inlets and the fluidic outlets.

[0023] 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 body surface that the skate covers is the radially external part of the body.

[0024] In preferred embodiments of the invention, the body 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 body undergoes a bending deformation stress and consequently tends to stress the pad against the second of said external and internal surfaces.

[0025] 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.

[0026] 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 containment of the fluid in said annular region of the annular space by means of the sealing device;

[0027] wherein a static contact between the pad and said second surface secures the rotating sealing segment to said second surface, while a seal dynamic is implemented between said dynamic sealing face of the body and said side of the annular groove. Brief description of the drawings

[0028] 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:

[0029] [Fig-1] is a partial schematic half-view in axial section of a system comprising a sealing segment, according to one embodiment of the invention;

[0030] [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);

[0031] [Fig.3] is a view of part of [Fig.1] at the scale of surface roughness and defects, illustrating a region of radial static contact within the system;

[0032] [Fig.4] is a larger scale view of part of [Fig.1], illustrating the operation of the system;

[0033] [Fig.5] is a view similar to [Fig.1], illustrating a system comprising a sealing segment, according to another embodiment of the invention;

[0034] [Fig.6] is a schematic half-view in axial section of a sealing segment according to one variant;

[0035] [Fig.7] is a schematic half-view in axial section of a sealing segment according to another variant;

[0036] [Fig.8] is a schematic half-view in axial section of a sealing segment according to yet another variant;

[0037] [Fig.9] is a schematic axial cross-sectional view of a system such as that of [Fig.1], configured as a multi-way fluid transfer system for an aircraft turbomachine;

[0038] [Fig. 10] is a schematic axial cross-sectional view of a turbomachine comprising a system such as that of [Fig.1].

[0039] Throughout these figures, identical references may designate identical or analogous elements. Detailed presentation of preferred embodiments I. General Application

[0040] 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 9.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] The device 200 (or each device 200) comprises an annular groove 202 formed in a first of the external surfaces 20A of the central part 20 and internal surfaces 22A of the peripheral part 22, in this case in the external surface 20A. This annular groove 202 has two opposing sides 204A, 204B connected to each other by a bottom 206. The device 200 further comprises a sealing segment 210 mounted in the annular groove 202.

[0046] 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 a corresponding radial end surface of the sealing segment 210, and by an axial dynamic contact between one of the flanks 204A, 204B of the annular groove 202 and a corresponding axial end surface of the sealing segment 210.

[0047] The example described corresponds to a configuration commonly referred to as a "piston" type configuration, in which the 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 segment 210 and the internal surface 22A of the peripheral part 22. The example described below is nevertheless transposable to a "rod" type configuration, that is to say, a configuration in which the 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 segment 210 and the external surface 20A of the central part 20.

[0048] According to a particular feature of the invention, the sealing segment 210 is formed by a body 212 and a pad 214.

[0049] The body 212 is in the form of a split ring, in a manner analogous to known types of sealing segments, and has a radially external surface 220, a radially internal surface 222, and opposing axial end surfaces 224 and 226.

[0050] The body 212 is made of a first material, preferably a metal or a metal alloy, generally chosen so that the body 212 has a flexural stiffness greater than that of the pad 214.

[0051] The pad 214 covers over 360 degrees one of the radially external and radially internal surfaces of the body 212, in this case the radially external surface 220, to which the pad 214 is rigidly attached.

[0052] The pad 214 is made of a second material, having a lower hardness than the first material. The comparison of the hardnesses of the two materials can be carried out 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.

[0053] The body 212 is configured such that its retention within the annular groove 202 results in a stress tending to open the split ring formed by the body 212, that is, tending to spread its ends apart by increasing the radius of curvature of the body 212. This has the effect of applying the pad 214 against the second of the external surfaces 20A and internal surfaces 22A, which is opposite the pad, in this case the internal surface 22A of the peripheral part 22. To this end, the body 212 is such that at rest, as illustrated by the dashed line in [Fig. 2], the body adopts a configuration in which the ends 212A, 212B of the body are further apart than in its service configuration, that is, the configuration that the body adopts under constraint within system 10, illustrated in continuous line on [Fig.2].

[0054] Furthermore, the ends 212A, 212B of the body 212 ([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 annular groove 202.

[0055] The body 212 is further shaped so that its surface, among its radially external surfaces 220 and radially internal surfaces 222, which is not the one covered by the pad 214, in this case its radially internal surface 222, is spaced from the bottom 206 of the annular groove 202 which is opposite this surface 222 (cf. [Fig.1]).

[0056] The stiffness of the body 212 thus contributes to keeping the pad 214 in close contact with the internal surface 22A while ensuring, due to the space present between the opposite surface 222 of the body and the bottom 206 of the annular groove, the absence of contact between the surface 222 of the body and the central part 20.

[0057] The pad 214 thus ensures the static radial contact between the sealing segment 210 and the internal surface 22A of the peripheral part.

[0058] Alternatively, in the case of a configuration reversed with respect to that described above, i.e. a "rod" type configuration, the pad 214 is arranged on the radially internal surface of the body 212 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 body 212, i.e. tending to bring the ends of the latter closer together by reducing the radius of curvature of the body, so as to apply the pad 214 against the external surface 20A of the central part 20.

[0059] Still with reference to [Fig.1], one of the axial end surfaces 224 and 226 of the body 212, in this case the surface 226, defines a dynamic sealing face, ensuring the axial dynamic contact between the sealing segment 210 and one of the flanks 204B of the annular groove 202, and therefore with the central part 20.

[0060] The body 212 and the 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.

[0061] In certain cases, particularly cases where the axial dynamic contact is intended to operate in a non-lubricated regime at least in certain transient phases of operation, the body 212 can be made of a self-lubricating material, for example a self-lubricating material based on PTFE, virgin or filled polyimide (PI), or graphite.

[0062] In general, the choice of an elastomeric material, or more generally a material of less hardness, to constitute the pad 214, makes it possible to considerably improve the sealing at the level of the radial static contact between the sealing segment 210 and the internal surface 22A of the peripheral part 22.

[0063] Indeed, as illustrated in [Fig.3], the low hardness of the second material allows the protruding irregularities or roughness of the internal surface 22A to penetrate into the pad 214 and thus prevent any circulation of fluid between the pad 214 and the surface 22A.

[0064] The flexibility of the pad 214 also allows it to deform to conform to larger-scale shape defects and deformations of the internal surface 22A, for example deformations caused by thermal expansions.

[0065] 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 pad 214, and the first material, constituting the body 212, is indeed generally greater than what the coefficient of friction would be between two elements made of the first material.

[0066] The risk of radial dynamic contact being established between the sealing segment 210 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 axial end surface 226 of the body 212.

[0067] 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 pad 214, and generally exhibiting a controlled or calibrated leakage flow LF, through the axial dynamic contact zone between the surface 226 or dynamic sealing face and the flank 204B of the annular groove 202.

[0068] In the embodiment of [Fig. 1], the body 212 has a shoulder 230 extending outward from the surface of the body covered by the pad 214, i.e. the radially external surface 220, so that the shoulder 230 forms a stop against an axial displacement of the pad 214 in a given axial direction Al, conveniently called the "first axial direction".

[0069] By positioning the shoulder 230 on the axial side opposite the annular region 23A in which the fluid is located, the shoulder 230 makes it possible to oppose the extrusion of the pad 214 under the axial pressure of the fluid.

[0070] Such a configuration of the sealing segment 210 is particularly advantageous in cases where the latter is intended to separate the annular region 23A from a region 23B without fluid or subjected to a lower fluid pressure than the region 23A, without risk of reversing the pressure differential between the two regions 23A and 23B.

[0071] In the case where the pressure differential is likely to reverse, for example when the sealing segment 210 separates two regions 23A and 23B each supplied with pressurized fluid, the embodiment of [Fig.5] is particularly advantageous.

[0072] In this embodiment, the body 212 has another shoulder 232, also projecting from the surface of the body covered by the pad 214, that is, the radially external surface 220, so that the shoulder 232 acts as a stop against axial displacement of the pad 214 in the axial direction A2 opposite to the axial direction Al and conveniently referred to as the "second axial direction". The pad 214 is thus interposed axially between the first shoulder 230 and the second shoulder 232, which prevents or at least limits any risk of extrusion of the pad 214 in either of the axial directions Al and A2.

[0073] This embodiment offers an additional advantage in that it allows the sealing segment 210 to be symmetrical, making the operation of the sealing segment independent of its orientation. This reduces the risk of assembly errors.

[0074] Furthermore, Figures 6-8 illustrate various possible cross-sections, as alternatives, for the surface 234 of the pad 214 intended to ensure radial static contact, for example, a convex cross-section ([Fig. 6]), a cross-section with two bumps 214A, 214B separated by a groove 214C ([Fig. 7]), or a grooved cross-section ([Fig. 8]). The configurations in Figures 6 and 7 have the particular advantage of being less susceptible to extrusion under high pressure. The configuration in [Fig. 8] has the particular advantage of improving static sealing because the grooves increase the deformation capacity of the pad 214.

[0075] Generally, the manufacture of the sealing segment 210 may involve producing the pad 214 using an adhesion technique, that is, by bonding the elastomer forming the pad 214 to the body 212 with a suitable chemical agent. However, other techniques for manufacturing the pad 214 while ensuring its attachment to the body 212 are possible within the scope of the present invention.

[0076] 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.

[0077] Furthermore, the implementation of the system 10 is such that a static contact between the pad 214 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 of the body 212 defined by the surface 226 of the latter, and the corresponding flank 204B of the annular groove 202. II. Specific Application

[0078] Fig. 9 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.

[0079] The stator includes, for example, a fluid supply structure (not shown in [Fig. 9]) 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."

[0080] The system 10 of [Fig.9] 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.

[0081] 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.

[0082] The central part 20 has the external surface 20A with a geometry of revolution about the axis 8, preferably cylindrical in shape. The peripheral part 22 has the internal surface 22A with a geometry of revolution about the axis 8, arranged around the external surface 20A of the central part 20, and preferably of a shape generally similar to the shape of the external surface 20A up to a homothetic transformation, the two surfaces possibly differing further by the presence of different orifices. and annular grooves. In the illustrated embodiment, the internal surface 22A of the peripheral part 22 is jointly defined 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 can be defined by a single part.

[0083] 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.

[0084] 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.

[0085] 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 corresponding fluidic inlet 14A-14C to a corresponding transfer chamber 24A-24C, the latter being further connected to a corresponding fluidic outlet 16A-16C by a corresponding second fluidic path FP2A-FP2C.

[0086] The fluidic inlets 14A-14C are defined by a longitudinal end portion of the central part 20 located on a first axial side SL. The fluidic outlets 16A-16C can be arranged at a longitudinal end of the peripheral part 22 located on a second axial side S2 opposite the first axial side SI and / or in an external surface 28 of the peripheral part 22. In the illustrated example, a fluidic outlet 16A is arranged at the longitudinal end of the peripheral part 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 part 22.

[0087] As mentioned above, the central part 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 part 20, while The peripheral portion 22 is configured to connect the fluidic outlets of system 16A-16C to the transfer chambers 24A-24C, respectively, through the internal surface 22A of the peripheral portion 22. The means for achieving this result will not be described here and are outside the scope of 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.

[0088] 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.

[0089] 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.

[0090] A method for implementing system 10 of the type described above with reference to [Fig. 9] 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.

[0091] Fig. 10 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.

[0092] The turbomachine comprises, for example, a low-pressure compressor 314, a high-pressure compressor 316, a combustion chamber 318, a high-pressure turbine A high-pressure compressor 320 and a low-pressure turbine 322 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.

[0093] The turbomachine includes a system 10 of the type described above, with axis 8 for example coinciding with axis 328 of the turbomachine 310.

[0094] 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.

[0095] The system 10, illustrated schematically in [Fig. 10], is arranged, for example, so that its fluidic outlets 16A-16C are connected to fluidic chambers of actuators mounted on the aforementioned rotor 340 to enable the control of such actuators. In particular, the device is, for example, of the type commonly known as an OTB (Oil Transfer Bearing) and is intended to supply a cylinder controlling the pitch of one or more propeller blades, 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) for confining the fluid (F) in at least one annular region (23A) within the annular space (23), comprising an 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 opposite flanks (204A, 204B) connected to each other by a bottom (206), and a sealing segment (210) mounted in the annular groove (202); in which the sealing segment (210) is formed by: • a split ring-shaped body (212) made of a first material, and having a radially external surface (220), a radially internal surface (222), and a dynamic sealing face (226) with respect to one of the flanks (204B) of the annular groove; and • a pad (214), made of a second material, covering one of the radially external (220) and radially internal (222) surfaces of the body to which the pad is rigidly attached, and applied against a second of said external (20A) and internal (22A) surfaces respectively of the central (20) and peripheral (22) parts, so that the pad (214) ensures static contact of the sealing segment (210) on said second surface all around the axis (8); the other of the radially external (220) and radially internal (222) surfaces of the body being arranged opposite - and spaced - from the bottom (206) of the annular groove; the first material being chosen so that the body (212) has a flexural stiffness greater than that of the pad (214), and the second material having a hardness less than that of the first material.

2. System according to claim 1, wherein the body (212) has a shoulder (230) extending in projection from said surface of the body covered by the pad (214), and thus forming a stop against an axial displacement of the pad in a first axial direction (Al).

3. System according to claim 2, wherein said shoulder (230) is a first shoulder, and wherein the body (212) has a second shoulder (232) extending outward from said surface of the body covered by the pad (214) and forming a stop against axial displacement of the pad in a second axial direction (A2) opposite to the first axial direction (A1), the pad (214) being axially interposed between the first shoulder (230) and the second shoulder (232).

4. System according to any one of claims 1 to 3, wherein the first material is selected from metals, metal alloys, self-lubricating plastics, graphite and composite materials.

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

6. A system according to any one of claims 1 to 5, 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 portion (20) defines first fluid paths (FP1A to FP1C) connecting fluid inlets (14A to 14C) of the system to the transfer chambers (24A to 24C) through said external surface (20A); • the peripheral portion (22) defines second fluid paths (FP2A to FP2C) connecting fluidic 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 fluidic inlets (14A to 14C) and the fluidic outlets (16A to 16C).

7. System according to any one of claims 1 to 6, 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 body (212) which the pad (214) covers is the radially external surface (220) of the body.

8. System according to claim 7, wherein the body (212) 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 body (212) is subjected to a bending deformation stress and consequently tends to stress the pad (214) against the second of said external (20A) and internal (22A) surfaces.

9. Aircraft turbomachine (310), comprising at least one system (10) according to any one of claims 1 to 8, and comprising a stator integral with one of the central (20) and peripheral (22) parts of the system and a rotor integral with the other central (20) or peripheral (22) part of the system.

10. A method for implementing a system (10) according to any one of claims 1 to 8, comprising: • driving at least one of the central (20) and peripheral (22) parts in rotation relative to the other; • supplying a fluid (F) to the annular space (23); and • confining the fluid (F) within said annular region (23A) of the annular space (23) by means of the sealing device (200); wherein a static contact between the pad (214) and said second surface secures the rotating sealing segment (210) with said second surface, while a dynamic seal is implemented between said dynamic sealing face (226) of the body (212) and said flank (204B) of the annular groove (202).

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