Dynamic sealing system comprising an improved sealing segment

Abstract

The invention relates to a dynamic sealing system comprising a central portion (20) with an outer surface (20A), a peripheral portion (22) with an inner surface (22A), a sealing device (200) comprising: a groove (202); and a sealing segment (210) which is formed by a split annular body (212) made of a first material and has a radially outer surface (220), a radially inner surface (222), and a dynamic sealing face (226) with respect to a side wall (204B) of the groove; and a block (214) which is made of a second material having a hardness greater than that of the first material, covers the surface (220) or (222) of the body to which the pad is rigidly connected, and is applied against one of the outer surface (20A) and inner surface (22A) such that the block (214) provides static contact between the sealing segment (210) and this surface. The other of the surfaces (220) and (222) of the body is opposite a bottom (206) of the groove. The body (212) has a higher bending stiffness than the block (214).

Description

[0001] Description

[0002] Title: Dynamic sealing system comprising an improved sealing segment

[0003] technical field

[0004] The present invention relates to the field of dynamic sealing between two concentric surfaces of revolution rotating relative to each other, and more particularly concerns 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.

[0005] 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.

[0006] Prior art

[0007] 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.

[0008] Among these solutions, seals of the type known as "piston rings" are valued for their compact size and effectiveness even under high fluid pressures (above 10 bar, for example). Pressures exceeding 100 bar are encountered, for instance, in devices designed to transfer a fluid (such as oil) between two reference points rotating relative to each other, for the purpose of actuating a variable pitch system for blades or vanes in an aircraft engine.

[0009] Such a sealing segment typically consists of a split ring-shaped metal body that can be temporarily deformed by spreading its ends apart to fit into an annular groove formed on one of two concentric surfaces. The ends of the segment are generally shaped to ensure a seal between them, for example, through various types of circumferential overlaps, or to provide controlled clearance when the segment is positioned within the annular groove.

[0010] With such a seal, the seal 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 on the other hand, by a dynamic axial contact between an axial end surface of the body and a corresponding flank of the annular groove. "Static contact" refers to contact between two static elements relative to each other, in this case the body of the segment and the second surface, while "dynamic contact" refers to contact with friction between two elements rotating relative to each other, in this case the body and the flank of the annular groove.In practice, after a break-in phase, friction at the dynamic contact level is reduced by means of a controlled or calibrated leakage rate of the fluid, accompanied by hydrodynamic effects between the two surfaces involved in the dynamic contact.

[0011] This type of seal is particularly appreciated because the wear, which occurs mainly at the axial end surface of the body involved in the axial dynamic contact, has only a reduced or even zero impact on the leakage rate at this point, since such wear is naturally compensated by the stress on the body of the seal against the corresponding side of the annular groove by the pressure of the fluid.

[0012] The quality of the radial static contact is a key parameter for limiting and / or controlling fluid leaks at such a sealing segment, particularly in the presence of a strong pressure differential on either side of the joint.

[0013] This quality of the static radial contact is generally limited by deformations that may affect one or the other of the concentric surfaces, such deformations being able to be caused in particular by centrifugal force or thermal expansions and thermomechanical deformations.

[0014] However, calculations show that the appearance of radial play at the static contact has a cube-dependent influence on the leakage rate. Therefore, there is a need to improve the way sealing is achieved between concentric surfaces rotating relative to each other using sealing segments.

[0015] Description of the invention

[0016] To address this need, the invention proposes a dynamic sealing system comprising:

[0017] - a central part presenting an external surface with a geometry of revolution around an axis;

[0018] - 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;

[0019] - an annular space defined between the external and internal surfaces to contain a fluid;

[0020] - at least one sealing device for confining the fluid within 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 opposing sides connected to each other by a bottom, and a sealing segment mounted in the annular groove; wherein the sealing segment is formed by:

[0021] - 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

[0022] - 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; 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; the first material being chosen so that the body has a flexural stiffness greater than that of the pad, and the second material having a hardness less than that of the first material.

[0023] Using different materials to ensure static and dynamic contact respectively allows each of these contacts to be optimized.

[0024] In particular, the choice of a less hard material to make up 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.

[0025] With regard to the body, the choice of a harder material, giving the body greater stiffness than the pad, optimizes the axial dynamic contact between the sealing segment and the corresponding side of the annular groove, ensures optimal geometry for the sealing segment, and ensures that the body forces the pad against the second surface.

[0026] In preferred embodiments of the invention, the body has a shoulder extending outward from said body surface covered by the pad, and thus forming a stop against axial displacement of the pad in a first axial direction.

[0027] In preferred embodiments of the invention, said shoulder is a first shoulder, and the body has a second shoulder extending outward from said body surface covered by the pad and forming a stop against 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.

[0028] In preferred embodiments of the invention, the first material is chosen from metals, metal alloys, self-lubricating plastics, graphite and composite materials.

[0029] In preferred embodiments of the invention, the second material is an elastomer. 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 defining first fluidic paths connecting respectively fluidic inlets of the system to the transfer chambers through said external surface, and the peripheral part defining second fluidic paths connecting respectively fluidic outlets of the system to the transfer chambers through said internal surface, the system thus being configured for the transfer of several fluid paths between the fluidic inlets and the fluidic outlets.

[0030] In preferred embodiments of the invention, the sealing segment is mounted in a piston configuration, whereby:

[0031] - said first surface is the external surface of the central part;

[0032] - said second surface is the internal surface of the peripheral part; and

[0033] - said surface of the body that the skate covers is the radially external surface of the body.

[0034] 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.

[0035] In preferred embodiments of the invention, the system is configured to establish an elasto-hydrodynamic (“EHD”) or hydrodynamic (“HD”) lubrication regime between said dynamic sealing face of the body and said flank of the annular groove, in operation.

[0036] In preferred embodiments of the invention, the skate is glued to the body.

[0037] In preferred embodiments of the invention, the skid is cylindrical in shape, as is the radially external or radially internal surface of the body that the skid covers. The invention also relates to an aircraft turbomachine comprising at least one system of the type defined above, and comprising a stator integral with one of the central and peripheral parts of the system and a rotor integral with the other central or peripheral part of the system.

[0038] The invention also relates to a method for implementing a system of the type defined above, comprising:

[0039] - the rotation of at least one of the central and peripheral parts relative to the other;

[0040] - the supply of a fluid to the annular space; and

[0041] - the circumscription of the fluid in said annular region of the annular space by means of the sealing device; in which a static contact between the pad and said second surface secures the rotating sealing segment with said second surface, while a dynamic seal is implemented between said dynamic sealing face of the body and said side of the annular groove.

[0042] In preferred embodiments of the invention, an elasto-hydrodynamic (“EHD”) or hydrodynamic (“HD”) lubrication regime is established between said dynamic sealing face of the body and said flank of the annular groove.

[0043] Brief description of the drawings

[0044] 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:

[0045] [Fig. 1] is a partial schematic half-view in axial section of a system comprising a sealing segment, according to an embodiment of the invention;

[0046] [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);

[0047] [Fig. 3] is a view of a portion of Figure 1 at the scale of surface roughness and defects, illustrating a region of radial static contact within the system; [Fig. 4] is a larger scale view of a portion of Figure 1, illustrating the operation of the system;

[0048] [Fig. 5] is a view similar to figure 1, illustrating a system comprising a sealing segment, according to another embodiment of the invention;

[0049] [Fig. 6] is a schematic half-view in axial section of a sealing segment according to one variant;

[0050] [Fig. 7] is a schematic half-view in axial section of a sealing segment according to another variant;

[0051] [Fig. 8] is a schematic half-view in axial section of a sealing segment according to yet another variant;

[0052] [Fig. 9] is a schematic axial cross-sectional view of a system such as that in Figure 1, configured as a multi-way fluid transfer system for an aircraft turbomachine;

[0053] [Fig. 10] is a schematic axial cross-sectional view of a turbomachine comprising a system such as that in Figure 1.

[0054] Throughout these figures, identical references may designate identical or analogous elements.

[0055] Detailed presentation of preferred embodiments

[0056] I. General Application

[0057] Figure 1 illustrates a dynamic sealing system 10, comprising a central part 20 and a peripheral part 22, shown schematically. Each of these parts can be a single component or an assembly of components. A specific example will be described in more detail below with reference to Figure 9.

[0058] Referring to Figure 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, and capable of rotation about the latter about the axis 8. In the following description, the axial direction X is the direction of the axis 8. The radial direction R is at every point a direction orthogonal to the axis 8 and passing through it, and the orthoradial or circumferential direction C is at every point a direction orthogonal to the radial direction R and to the axis 8. A transverse plane is a plane orthogonal to the axis 8. Unless otherwise indicated, the terms "internal" and "external" refer respectively to a relative proximity and a relative distance of an element from the axis 8. Furthermore, the term "axial" is used in reference to axis 8.

[0059] 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 includes means such as channels or conduits for supplying such a fluid to the annular space 23.

[0060] To confine the fluid within at least one annular region 23A within the annular space 23 (for example on the left in Figure 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.

[0061] 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.

[0062] 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.

[0063] 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 intended 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 intended to occur between a radially internal surface of the sealing segment 210 and the external surface 20A of the central part 20.

[0064] According to a particular feature of the invention, the sealing segment 210 is formed by a body 212 and a pad 214.

[0065] 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.

[0066] 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.

[0067] The skate 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 skate 214 is rigidly attached.

[0068] The 214 pad is made of a second material with a lower hardness than the first material. The hardness of the two materials can be compared using 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.

[0069] The body 212 is configured so 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 Figure 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 stress within the system 10, illustrated in continuous line on figure 2.

[0070] Furthermore, the ends 212A, 212B of the body 212 (figure 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.

[0071] 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 (see figure 1).

[0072] The stiffness of the body 212 thus helps to keep the skate 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.

[0073] The pad 214 thus ensures the static radial contact between the sealing segment 210 and the internal surface 22A of the peripheral part.

[0074] Alternatively, in the case of a reversed configuration compared 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.

[0075] With further reference to Figure 1, one of the axial end surfaces 224 and 226 of the body 212, in this case 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.

[0076] 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 minimizes wear on the surfaces involved in this axial dynamic contact.

[0077] In some cases, particularly those 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 may be made of a self-lubricating material, for example a self-lubricating material based on PTFE, virgin or filled polyimide (PI), or graphite.

[0078] 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 static radial contact between the sealing segment 210 and the internal surface 22A of the peripheral part 22.

[0079] Indeed, as illustrated in Figure 3, the low hardness of the second material allows the protruding irregularities or roughness of the internal surface 22A to penetrate the pad 214 and thus prevent any circulation of fluid between the pad 214 and the surface 22A.

[0080] The flexibility of the pad 214 also allows it to deform to accommodate larger-scale shape defects and deformations of the internal surface 22A, such as deformations caused by thermal expansion. Furthermore, the rotational connection of the sealing segment 210 to 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 generally greater than the coefficient of friction that would be between two elements made of the first material.

[0081] The risk of radial dynamic contact occurring 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 solely on the dynamic sealing face defined by the axial end surface 226 of the body 212.

[0082] Figure 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.

[0083] In the embodiment of Figure 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".

[0084] 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.

[0085] 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.

[0086] 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 Figure 5 is particularly advantageous.

[0087] In this embodiment, the body 212 has another shoulder 232, also projecting from the surface of the body covered by the pad 214, namely the radially external surface 220, such 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, thereby preventing or at least limiting any risk of extrusion of the pad 214 in either of the axial directions Al and A2.

[0088] This embodiment offers an additional advantage: the possibility of giving the sealing segment 210 a symmetrical character, making the sealing segment's function independent of its orientation. This reduces the risk of assembly errors.

[0089] Furthermore, Figures 6-8 illustrate various possible cross-sections for the surface 234 of the pad 214 intended to ensure radial static contact, for example, a convex cross-section (Figure 6), a cross-section with two bumps 214A, 214B separated by a groove 214C (Figure 7), or a grooved cross-section (Figure 8). The configurations in Figures 6 and 7 have the particular advantage of being less susceptible to extrusion under high pressure. The configuration in Figure 8 has the particular advantage of improving static sealing because the grooves increase the deformation capacity of the pad 214.

[0090] 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.

[0091] As explained above, the implementation of system 10 generally involves: - driving at least one of the central 20 and peripheral 22 parts in rotation relative to the other;

[0092] - the supply of fluid to the annular space 23; and

[0093] - the circumscription of the fluid in the annular region 23A of the annular space 23 by means of the sealing device 200.

[0094] 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.

[0095] II. Specific Application

[0096] Figure 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.

[0097] The stator, for example, includes a fluid supply structure (not shown in Figure 9) with 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 this description, for convenience, assumes a direction of fluid flow from the fluid inlets to the fluid outlets through the system 10, a reverse flow direction is possible. In this respect, the terms "inlet" and "outlet" should be considered synonymous with passage orifices or "fluid ports." The system 10 in Figure 9 generally comprises the central part 20 and the peripheral part 22 arranged around the central part 20 and capable of rotation about the latter along axis 8.

[0098] The central part 20, for example, is designed to be integral with the stator, in this case the aforementioned fluid supply structure, while the peripheral part 22, for example, is designed 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.

[0099] The central portion 20 has an external surface 20A with a geometry of revolution about axis 8, preferably cylindrical in shape. The peripheral portion 22 has an internal surface 22A with a geometry of revolution about axis 8, arranged around the external surface 20A of the central portion 20, and preferably with a shape broadly similar to that of the external surface 20A up to a homothetic transformation. The two surfaces may further differ in the presence of different annular orifices and grooves. In the illustrated embodiment, the internal surface 22A of the peripheral portion 22 is defined jointly by several parts constituting the peripheral portion 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 portion 22 may be defined by a single part.

[0100] The annular space 23 is, as above, defined between the external surface 20A of the central part 20 and the internal surface 22A of the peripheral part 22.

[0101] 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. For each of the fluid paths to be transferred, the central part 20 includes a fluidic path in fluidic communication with a corresponding fluidic path within the peripheral part 22, in order to allow circulation of the fluid of the path considered from a corresponding fluidic inlet 14A-14C attached to the central part 20, to a corresponding fluidic outlet 16A-16C attached to the peripheral part 22.Furthermore, the two-to-two communication between the fluidic paths of the central part 20, referred to as first fluidic paths hereafter and referenced FP1A-FP1C, and the fluidic paths of the peripheral part 22, referred to as second fluidic paths hereafter 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.

[0102] 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.

[0103] As mentioned above, the central portion 20 is configured to connect the fluidic inlets of 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 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

[0104] France on October 20, 2023 under number FR2311395.

[0105] 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.

[0106] 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.

[0107] A method for implementing system 10 of the type described above with reference to Figure 9 generally comprises:

[0108] - selective fluid supply to the first fluidic paths FP1A-FP1C, via the fluidic inlets 14A-14C of the system;

[0109] - the circulation of the fluid in the first fluidic paths FP1A-FP1C up to the transfer chambers 24A-24C;

[0110] - 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.

[0111] Figure 10 illustrates a turbomachine 310, for example a twin-spool turbofan engine for aircraft, generally comprising a fan 312 for drawing in an airflow Fl which, downstream of the fan, divides into a primary flow F2 flowing in a primary flow channel, hereinafter referred to as the primary stream PV, and a secondary flow F3 flowing in a secondary flow channel, hereinafter referred to as the secondary stream SV, arranged around the primary stream PV. The turbomachine includes, 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 stream 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 328 axis of the turbomachine.

[0112] The turbomachine includes a system 10 of the type described above, with axis 8 for example coinciding with axis 328 of the turbomachine 310.

[0113] 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.

[0114] System 10, schematically illustrated in Figure 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 designed to supply a cylinder controlling the pitch of one or more propeller blades, as well as a blade safety actuator.

Claims

Demands 1. 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) within 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 opposing flanks (204A, 204B) connected to each other by a base (206), and a sealing segment (210) mounted in the annular groove (202); wherein the sealing segment (210) is formed by: - a body (212) in the shape of a split ring, 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 skate (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 outward 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 an axial displacement of the pad in a second axial direction (A2) opposite to the first axial direction (A1), the pad (214) being interposed axially 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 part (20) defines first fluidic paths (FP1A to FP1C) connecting respectively fluidic 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 fluidic paths (FP2A to FP2C) connecting respectively 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. A system according to any one of claims 1 to 6, wherein the sealing segment (210) is in a piston-mounted configuration, whereby: - 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 skate (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) undergoes a bending deformation stress and consequently tends to stress the pad (214) against the second of said external (20A) and internal (22A) surfaces.

9. System according to any one of claims 1 to 8, configured to establish an elasto-hydrodynamic or hydrodynamic lubrication regime between said dynamic sealing face (226) of the body (212) and said flank (204B) of the annular groove (202), in operation.

10. System according to any one of claims 1 to 9, wherein the pad (214) is glued to the body (212).

11. System according to any one of claims 1 to 10, wherein the pad (214) is cylindrical in shape of revolution, as is the radially external surface (220) or radially internal surface (222) of the body (212) which the pad (214) covers.

12. Aircraft turbomachine (310), comprising at least one system (10) according to any one of claims 1 to 11, 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.

13. A method for implementing a system (10) according to any one of claims 1 to 8, 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); 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).

14. Method according to claim 13, wherein an elasto-hydrodynamic or hydrodynamic lubrication regime is established between said dynamic sealing face (226) of the body (212) and said flank (204B) of the annular groove (202).

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