Turbomachine comprising a variable-damping bearing damper

Abstract

The invention relates to a turbomachine comprising a variable-damping bearing damper, wherein said damper comprises a rotating shaft, a bearing (18) supporting said rotating shaft, a bearing support (20) supporting said bearing, and an intermediate bushing (24) disposed between said bearing and said bearing support, wherein said intermediate bushing (24) is configured to slide axially with respect to said bearing, and a first sealing section (36) is axially coupled with said bearing and a second sealing section (38) is axially coupled with said intermediate bushing, and wherein said first sealing section, said second sealing section, said bearing and said intermediate bushing define a chamber (40) having a variable axial length (L) which, when filled with oil, forms a variable-damping oil film, wherein a return device (60) applies an elastic return force (E), said return device being configured to return said intermediate bushing to a given rest axial position with respect to said bearing.

Description

Technical Field

[0001] This invention relates to a turbine including a variable damping bearing damper.

[0002] The term "turbine" encompasses all gas turbine devices that generate driving power, which can be distinguished into the following types: turbojet engines, which provide the thrust required for propulsion through the reaction force of hot exhaust gases at high speeds; and turboshaft engines, whose driving power is provided by the rotation of an engine shaft. For example, turboshaft engines are used as engines for helicopters, ships, trains, or as industrial engines. Turboprop engines (turboshaft engines that drive propellers) are also turboshaft engines used as aircraft engines. Background Technology

[0003] Various turbine bearing dampers are known, for example by EP 2 753 844 or FR 2 629 537. However, these dampers are more or less effective depending on the operating range of the turbine.

[0004] FR 3 096 072 is also known prior art, which proposes to modify the damping of the bearing damper by modifying the length of the damping oil film through the use of an actuator axial displacement intermediate bushing.

[0005] However, while this configuration does allow the damping to adapt to the turbine's operating range, it requires active control, which makes implementation quite complex.

[0006] Therefore, there is indeed a need for a variable damping bearing damper that does not at least partially have the inherent disadvantages of the aforementioned known configurations. Summary of the Invention

[0007] This invention relates to a turbine extending in both the axial and radial directions, comprising:

[0008] At least one axis of rotation

[0009] At least one bearing supports the rotating shaft.

[0010] Bearing support, which supports the bearing

[0011] An intermediate bushing, radially disposed between the bearing and the bearing support, is configured to slide axially relative to the bearing.

[0012] The first sealing section is radially disposed between the bearing and the intermediate bushing, and is axially coupled to the bearing.

[0013] The second sealing section is radially disposed between the bearing and the intermediate bushing, and is axially coupled to the intermediate bushing.

[0014] The first sealing section, the second sealing section, the bearing, and the intermediate bushing define a chamber configured to receive oil. The axial length of the chamber is variable depending on the axial position of the intermediate bushing relative to the bearing, thereby forming a variable damping oil film when the chamber is filled with oil.

[0015] The return device applies an elastic restoring force and is configured to return the intermediate bushing to a given resting axial position relative to the bearing. A spring element can mechanically connect the bearing support and the bearing.

[0016] Generally, the axial direction corresponds to the axis of the turbine shaft, while the radial direction is perpendicular to the axial direction. The circumferential direction corresponds to the direction describing a ring around the axial direction. The axial, radial, and circumferential directions correspond to the directions defined by height, radius, and angle in a cylindrical coordinate system, respectively. Finally, unless otherwise stated, the adjectives "inner" and "outer" (or "inward" and "outward") are used with reference to the radial direction, such that the inner (i.e., radially inner) portion of the element is closer to the axis of the shaft than the outer (i.e., radially outer) portion of the same element.

[0017] It should be understood that the intermediate bushing is configured to slide in the axial direction, thereby changing the axial length of the chamber. Specifically, the first sealing section is axially coupled to the bearing, while the second sealing section is axially coupled to the intermediate bushing. Therefore, by displacing the intermediate bushing axially relative to the bearing, the first sealing section is axially displaced relative to the second sealing section. Thus, the chamber is defined radially by the bearing on one side and the intermediate bushing on the other, and axially by the first sealing section on one side and the second sealing section on the other. By displacing the intermediate bushing axially relative to the bearing, the axial length separating the first and second sealing sections is changed, thereby changing the axial length of the chamber.

[0018] The inventors discovered that during operation, by changing the axial length of the chamber, the volume of the active oil within the chamber and the resulting damping (viscous resistance) change accordingly. Therefore, the damping can adapt to the turbine speed, making the system effective across the entire speed range of the turbine. In other words, existing damping devices can only effectively dampen a single natural vibration mode of the shaft, while by changing the viscous resistance, multiple different natural vibration modes of the rotor can be damped.

[0019] Furthermore, in the proposed configuration, the position of the intermediate bushing and the viscous resistance of the damper automatically depend on the oil pressure in the chamber. Specifically, under low pressure, when the turbine is running at low speed, the return device returns the intermediate bushing to its stationary position; then, when the turbine is running at high speed and the oil pressure increases accordingly, the resultant force of the pressure exerted by the damping oil on the intermediate bushing tends to cancel out and exceed the elastic restoring force of the return device, thereby causing the intermediate bushing to displace axially in the direction opposite to its stationary axial position.

[0020] Then, the geometric parameters of the bearings, intermediate bushings, and springs can be adjusted according to the turbine's operating range to adjust the chamber volume, thereby adjusting its damping.

[0021] In particular, this configuration allows for such adjustments to be made in a passive and automatic manner without the need for actuators to displace the intermediate bushing.

[0022] In some embodiments, the intermediate bushing is configured to overcome the elastic restoring force of the return device and axially displace relative to the bearing under the pressure of the damping oil present in the chamber.

[0023] In some implementations, the intermediate bushing does not have any active actuator.

[0024] In some embodiments, the return mechanism is a leaf spring disposed between the intermediate bushing and the bearing or the bearing support.

[0025] In some embodiments, the first end of the leaf spring is fixed in the bearing or the bearing support, while the second end of the leaf spring abuts against the shoulder of the intermediate bushing.

[0026] In some embodiments, the return mechanism is a compression spring, such as a helical spring, which is compressed between the intermediate bushing and the bearing or the bearing support.

[0027] In some embodiments, the compression spring is received in a notch in the intermediate bushing, located between the shoulder of the notch and the protrusion of the bearing or bearing support embedded in the notch.

[0028] In some embodiments, the first sealing segment is received in an annular groove formed on the outer surface of the bearing. This configuration ensures reliable and effective axial coupling of the first sealing segment. For example, the first sealing segment also interacts with a uniform portion of the inner surface of the intermediate bushing.

[0029] In some embodiments, the outer surface of the bearing includes a recess in which a second sealing section is positioned, the second sealing section partially widening the chamber to form a first cavity, the volume of which can vary depending on the axial position of the intermediate bushing relative to the bearing. This cavity with greater thickness increases the combined pressure exerted by the oil on the second sealing section, thereby simplifying the operation of the intermediate bushing. Furthermore, it allows for a more rapid increase in the volume of damping oil present in the chamber with the displacement of the intermediate bushing, enabling adjustment of the damper's viscous resistance over a wide range while maintaining overall compactness.

[0030] In some embodiments, the intermediate bushing includes an inner protrusion that extends radially inward to be positioned in a recess on the outer surface of the bearing.

[0031] In some embodiments, the second sealing section is mounted against a shoulder formed by the inner protrusion of the intermediate bushing.

[0032] In some embodiments, the bearing support includes a recess, wherein the intermediate bushing includes an outwardly extending portion to be positioned within the recess of the bearing support, wherein the recess of the bearing support and the outwardly extending portion of the intermediate bushing form a second cavity configured to receive damping oil, the volume of which can vary depending on the axial position of the intermediate bushing relative to the bearing. This second cavity can increase the resultant force of the oil pressure exerted on the intermediate bushing, simplifying its operation. However, this second cavity does not necessarily form part of a chamber and therefore does not necessarily contribute to bearing damping.

[0033] In some embodiments, the end of the protrusion is flush with the inner surface of the bearing support, and a sealing section may be provided at the end of the protrusion.

[0034] In some embodiments, the bearing support includes a first oil passage connecting an oil inlet to the chamber. This first oil passage can supply oil to the chamber. The supply flow rate and the pressure of the oil present in the chamber can depend on the turbine speed, and in particular, be proportional to the rotational speed of one of its components.

[0035] In some embodiments, the bearing support includes a second oil passage connecting an oil inlet to the second cavity. This second oil passage can supply oil to the second cavity. This second oil passage can bypass the first oil passage. A valve or flow limiter may be provided on this second oil passage.

[0036] In some embodiments, the turbine includes a first axial stop configured to axially lock the intermediate bushing relative to the bearing at the given rest axial position of the intermediate bushing.

[0037] In some embodiments, the first axial stop is disposed on the outer surface of the bearing. This position can limit the overall dimensions.

[0038] In some embodiments, the first axial stop has a tapered profile, and the intermediate bushing includes a stop surface configured to abut against the first axial stop, the stop surface having a tapered profile that coincides with the tapered profile of the first axial stop. Due to this configuration, when the turbine operates at low speeds and the intermediate bushing is in or near its rest axial position, the tapered profile of the intermediate bushing's stop surface interacts with the tapered profile of the first axial stop, which tends to reduce or even completely lock the radial position of the intermediate bushing. Therefore, at low speeds, when the damping oil pressure is insufficient to prevent contact, the interaction of these tapered profiles can lock the radial offset of the intermediate bushing, thereby preventing wear of the system due to friction; furthermore, this allows the bushing to be locked to eliminate the damping effect of the oil film and the flexibility generated by the spring elements, which may be ideal at low speeds to utilize more favorable modal states of the rotor.

[0039] In some embodiments, the turbine includes a second axial stop configured to axially lock the intermediate bushing relative to the bearing at a given stop axial position relative to the bearing in a direction opposite to the restoring force of the restoring device.

[0040] In some embodiments, the second axial stop extends from the outer surface of the bearing to be supported by the bearing from the inner protrusion of the intermediate bushing when the intermediate bushing is in its given stop axial position.

[0041] In some embodiments, the bearing support and the intermediate bushing interact via an axially extending sliding coupling structure. This sliding coupling structure can alter the axial distance between the sealing sections, thereby changing the effective length of the oil film.

[0042] In some embodiments, the spring element is a variable stiffness spring element. The combination of a variable stiffness spring element and a variable damper can further dampen a wider range of the shaft's inherent modes / a wider range of turbine speeds. Examples of variable stiffness spring elements are described in document FR 17 62885.

[0043] The above-described features and advantages, as well as other features and advantages, will become apparent upon reading the following detailed description of exemplary embodiments of the proposed turbine. This detailed description refers to the accompanying drawings. Attached Figure Description

[0044] The subject matter and advantages of the invention will be better understood by reading the following detailed description of different embodiments given by way of non-limiting examples.

[0045] In these figures, the same elements (or parts of elements) are identified by the same reference numerals from one figure to the next. Furthermore, elements (or parts of elements) belonging to different exemplary embodiments but having similar functions are identified in the figures by adding reference numerals such as 100, 200, etc.

[0046] [ Figure 1 ] Figure 1 This is a schematic cross-sectional view of a turbine.

[0047] [ Figure 2 ] Figure 2 The first example of a bearing is shown, in its first state.

[0048] [ Figure 3 ] Figure 3 The first example of the bearing is shown, which is in the second state.

[0049] [ Figure 4 ] Figure 4 A second example of a bearing is shown.

[0050] [ Figure 5 ] Figure 5 A third example of a bearing is shown.

[0051] [ Figure 6 ] Figure 6 The fourth example of a bearing is shown. Detailed Implementation

[0052] Figure 1 A turbine 10 is schematically shown, in this example a gas turbine engine, and more specifically a turbofan engine. The turbine 10 extends along an axial direction X, a radial direction R, and a circumferential direction C. The turbine 10 includes a fan 11, a compressor 12, a combustion chamber 13, a first turbine 14, and a second turbine 15, which are arranged sequentially along the flow direction M of air and combustion gas through which they pass. However, the teachings of the present invention are also applicable to other types of gas turbine engines, such as turbojet engines, turboprop engines, or turboshaft engines, as well as other types of turbines and rotating machinery.

[0053] In turbine 10, fan 11 is rotatably coupled to second turbine 15 via first coaxial rotating shaft 16 and second coaxial rotating shaft 17, and compressor 12 is rotatably coupled to first turbine 14. These coaxial rotating shafts 16 and 17 are supported in the casing 19 of turbine 10 by corresponding bearings 18.

[0054] ReferenceFigure 2 and Figure 3 A first example of a turbine structure surrounding bearing 18 is described. This description pertains to the structure surrounding a single bearing 18, but applies to all bearings 18.

[0055] Figure 2 and Figure 3 The bearing 18 shown supports the shaft 16. The bearing 18 itself is supported by the bearing support 20. An annular spring element 22 mechanically connects the bearing 18 and the bearing support 20. An intermediate bushing 24 is radially disposed between the bearing 18 and the bearing support 20.

[0056] In this example, bearing 18 is a ball bearing and includes an inner bushing 18A, an outer bushing 18B, and balls 18C disposed between the inner bushing 18A and the outer bushing 18B, supporting the shaft 16. The outer bushing 18B is mounted on a bearing ring 18D, which is mechanically connected to the bearing support 20 via a spring element 22. In this example, the bearing ring 18D and the spring element 22 form a single component attached to the bearing support 20.

[0057] In this example, the spring element 22 is a spring element with a fixed stiffness. More specifically, in this example, the spring element 22 includes a flexible cage having a first elastic flexible member 22A extending in the axial direction X. The first member 22A has a first axial end 22A1 and a second axial end 22A2, the first axial end 22A1 being connected to the bearing 18, and more specifically to the bearing ring 18D. The flexible cage also has a second elastic flexible member 22B extending in the axial direction X. The second member 22B has a first end 22B1, which is connected to the bearing support 20; and a second end 22B2, which is connected to the second end 22A2 of the first member 22A. Therefore, the radial force F can be transmitted between the bearing 18 and the bearing support 20 through the bending of the first elastic flexible member 22A and the second elastic flexible member 22B.

[0058] The bearing ring 18D includes a main body portion 18D1 and a lateral portion 18D2, and the outer bushing 18B of the bearing 18 is mounted against the main body portion 18D1. The thickness of the lateral portion 18D2 is less than the thickness of the main body portion 18D1, such that the outer surface 19E of the bearing ring 18D has a recess 19A forming a shoulder 19B at the interface between the main body portion 18D1 and the lateral portion 18D2.

[0059] An intermediate bushing 24 is radially disposed between the bearing support 20 and the bearing 18 (more specifically, the bearing ring 18D of the bearing 18) and is configured to slide axially relative to the bearing 18. The outer surface 25E of the intermediate bushing 24 interacts with the outer surface 19E of the bearing ring 18D. More precisely, the intermediate bushing 24 interacts with the bearing support 20 via an axially extending sliding coupling structure (e.g., using a system of interlocking axial grooves / ribs).

[0060] The intermediate bushing 24 includes a flange 51 at its first axial end 24F that extends radially outward to form a shoulder 51A. At its second axial end 24G, opposite the first axial end 24F, the intermediate bushing 24 includes a flange 52 forming an inwardly protruding portion that extends radially inward to form a shoulder 52A. The inner end of the flange 52 is positioned in a recess 19A of the bearing ring 18D and thus partially protrudes from the shoulder 19B facing the bearing ring 18D.

[0061] The intermediate bushing 24 interacts with the bearing ring 18D via a first sealing section 36 and a second sealing section 38. The first sealing section 36 is received in an annular groove 18D3 formed on the outer surface 19E of the bearing 18, thereby axially coupling with the bearing 18. The second sealing section 38 is mounted against a shoulder 52A formed by the flange 52, thereby axially coupling with the intermediate bushing 24. Thus, the first sealing section 36, the second sealing section 38, the intermediate bushing 24 (and more specifically, the inner surface 25I of the intermediate bushing 24 in this example), and the bearing 18 (and more specifically, the outer surface 19E of the bearing ring 18D of the bearing 18 in this example) form a chamber 40. Since the intermediate bushing 24 is axially movable relative to the bearing 18, the first sealing section 36 is axially coupled relative to the bearing 18, and the second sealing section 38 is coupled to the intermediate bushing 24, the axial length L of the chamber 40 varies according to the relative axial position of the intermediate bushing 24 relative to the bearing 18.

[0062] Chamber 40 has an oil supply port 24C formed on the intermediate bushing 24. Note that an oil accumulator 42 is formed between the intermediate bushing 24 and the bearing support 20. This chamber 42 can form an oil accumulator for supplying oil to chamber 40 through the port 24C (in this example, the port 24C fluidly communicates chamber 40 and chamber 42). Chamber 42 is supplied with oil in a known manner through the oil supply passage 20A. Therefore, during operation, the oil follows... Figure 2 The flow is indicated by the dashed line.

[0063] The bearing ring 20D has an axial stop 18E, which is configured to interact axially with the first axial end 24F of the intermediate bushing 24.

[0064] The elastic recovery device 60 is installed in the direction that brings the sealing sections 36 and 38 closer together, thereby reducing the length L of the chamber 40 (i.e., in...).Figure 2 (From center to left) axially push the intermediate bushing 24. In this example, the elastic return device is a leaf spring 60, the first end of which is fixed in the second member 22B of the spring element 22 (at its end 22B1 attached to the bearing support 20), and the second end abuts against the shoulder 51A formed by the flange 51 of the intermediate bushing 24.

[0065] When there is no significant pressure in chamber 40, such as Figure 2 As shown, the spring 60 applies a restoring force E, which returns the intermediate bushing 40 to a stationary axial position, in which the end 24F of the intermediate bushing 24 abuts tightly against the axial stop 18E of the bearing 18, and / or the second sealing section 38 abuts tightly against the shoulder 19B of the bearing 18.

[0066] Conversely, as the pressure in chamber 40 increases, particularly as the speed of turbine 1 increases, the resultant force P of the pressure in chamber 40 tends to push the intermediate bushing 24 in a manner opposite to the restoring force of spring 60. Specifically, due to the recess 19A of bearing ring 18D, oil cavity 46 expands within chamber 40 between shoulder 19B and the second sealing section 38: the pressure of the oil present in this oil cavity 46 tends to push the second sealing section 38, thereby pushing the intermediate bushing 24. Therefore, as... Figure 3 As shown, when the resultant force P of the pressure exceeds the elastic restoring force E of the spring 60, the intermediate bushing 24 is axially displaced away from its resting axial position, which increases the axial length L of the chamber 40.

[0067] Therefore, when the pressure of the damping oil in chamber 40 increases, the intermediate bushing 24 automatically shifts to increase the volume of oil in chamber 40, which changes the damping parameters of bearing 18.

[0068] Figure 4 A second example of the structure surrounding bearing 118 is shown. This second example is completely similar to the first example, except that: in this second example, the inner surface 121I of bearing support 120 has a recess 129, and the intermediate bushing 124 includes an outer flange 153 (forming an outer protrusion) at its end 124G, which extends radially outward into the space of the recess 129 until it is flush with the inner surface 121I of bearing support 120. A second oil cavity 147 then expands within the recess 129 of bearing support 120, located between a shoulder 129A formed by the recess 129 and the outer flange 153 of intermediate bushing 124. The second oil cavity 147 is supplied with oil using an oil supply passage 120B connected to an oil supply passage 120A of chamber 140. A sealing section 153A is provided at the radial end of the flange 153 to ensure a seal of the second oil cavity 147.

[0069] Therefore, in this second example, the resultant force P2 of the pressure in the second chamber 147 is added to the resultant force P1 of the pressure in the chamber 140 to promote the axial displacement of the intermediate bushing 124 against the elastic restoring force E of the restoring device 160.

[0070] Furthermore, in this second example, the bearing ring 120D has a second axial stop 118F, which is configured to interact axially with the second axial end 124G of the intermediate bushing 124. This second axial stop 118F can thus limit the travel of the intermediate bushing 124 in the opposite direction to the elastic restoring force E of the spring 160.

[0071] Figure 5 A third example of the structure surrounding bearing 218 is shown. This third example is completely similar to the second example, except that in this third example, the leaf spring is replaced by a compression spring 260 of the coil spring type. In this example, the spring 260 is mounted in a notch 254 of the intermediate bushing 224, between the shoulder 254A of the notch 254 and the finger 228 of the bearing support 220 entering the notch 254.

[0072] Figure 6 A fourth example of the structure surrounding bearing 318 is shown. This fourth example is completely similar to the second example, except that in this fourth example, the axial stop 318E has a tapered profile. Similarly, the axial end 324F of the intermediate bushing 324 has a tapered profile complementary to that of the axial stop 318E. Therefore, at low speeds, the intermediate bushing 324 is returned to abutment against the axial stop 318E by an elastic return device 360, and the tapered profile of the axial stop 318E subsequently restricts or completely prevents the intermediate bushing 324 from moving freely in the radial direction.

[0073] Furthermore, in this fourth example, the spring 360 is still a leaf spring, but the mounting method is different. In this example, the first end of the leaf spring 360 is fixed to the outer surface 325E of the intermediate bushing 324, near its axial end 324F, while its second end abuts against the side surface 327 of the bearing support 320.

[0074] Although the invention has been described with reference to specific embodiments, it will be apparent that modifications and variations can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, features of the different embodiments shown / mentioned may be combined in additional embodiments. Therefore, the specification and drawings should be regarded as illustrative rather than restrictive.

[0075] It is equally evident that all features described by reference to the method can be applied individually or in combination to the apparatus, and vice versa, all features described by reference to the apparatus can be applied individually or in combination to the method.

Claims

1. A turbine (10) extending along an axial direction (X) and a radial direction (R), comprising: At least one rotation axis (16, 17). At least one bearing (18) supports the rotating shaft (16, 17). Bearing support (20) supports the bearing (18). An intermediate bushing (24), radially disposed between the bearing (18) and the bearing support (20), is configured to slide axially relative to the bearing (18). The first sealing section (36) is radially disposed between the bearing (18) and the intermediate bushing (24), and is axially coupled to the bearing (18). The second sealing section (38) is radially disposed between the bearing (18) and the intermediate bushing (24), and is axially coupled to the intermediate bushing (24). The first sealing section (36), the second sealing section (38), the bearing (18), and the intermediate bushing (24) define a chamber (40) configured to receive oil. The axial length (L) of the chamber (40) can vary according to the axial position of the intermediate bushing (40) relative to the bearing (18), thereby forming a variable damping oil film when the chamber (40) is filled with oil. The return device (60) applies an elastic restoring force (E) and is configured to return the intermediate bushing (24) to a given rest axial position relative to the bearing (18).

2. The turbine (10) according to claim 1, wherein, The intermediate bushing (24) is configured to, under the pressure of the damping oil present in the chamber (40), overcome the elastic restoring force (E) of the return device (60) and axially displace relative to the bearing (18).

3. The turbine (10) according to claim 1 or 2, wherein, The recovery device is a leaf spring (60) disposed between the intermediate bushing (24) and the bearing (18) or the bearing support (20).

4. The turbine (210) according to claim 1 or 2, wherein, The return mechanism is a compression spring (260), such as a helical spring, compressed between the intermediate bushing (224) and the bearing (218) or the bearing support (220).

5. The turbine (10) according to any one of claims 1 to 4, wherein, The outer surface (19E) of the bearing (18) includes a recess (19A) in which a second sealing section (38) is positioned, the second sealing section (38) partially widening the chamber (40) to form a first cavity (46), the volume of which can vary according to the axial position of the intermediate bushing (24) relative to the bearing (18).

6. The turbine (10) according to claim 5, wherein, The intermediate bushing (24) includes an inner protrusion (52) that extends radially inward to be positioned in a recess (19A) on the outer surface (19E) of the bearing (18), and The second sealing section (38) is mounted against a shoulder (52A) formed by the inner protrusion (52) of the intermediate bushing (24).

7. The turbine (110) according to any one of claims 1 to 6, wherein, The bearing support (120) includes a recess (129). The intermediate bushing (124) includes an outwardly protruding portion (153) that extends radially outward to be positioned within a recess (129) of the bearing support (120). The recess (129) of the bearing support (120) and the protrusion (153) of the intermediate bushing (124) form a second cavity (147), which is configured to receive damping oil, and the volume of the second cavity can vary according to the axial position of the intermediate bushing (124) relative to the bearing (118).

8. The turbine (110) according to claim 7, wherein, The bearing support (120) includes a first oil passage (120A) that connects an oil inlet to the chamber (140), and The bearing support (120) includes a second oil passage (120B) that connects the oil inlet to the second cavity (147).

9. The turbine (310) according to any one of claims 1 to 8, comprising a first axial stop (318E) configured to axially lock the intermediate bushing (324) relative to the bearing (318) at the given rest axial position of the intermediate bushing (324) relative to the bearing (318). in, The first axial stop (318E) is disposed on the outer surface (319E) of the bearing (318). The first axial stop (318E) has a tapered profile, and The intermediate bushing (324) includes a stop surface configured to abut against the first axial stop (318E), the stop surface having a tapered profile that coincides with the tapered profile of the first axial stop (318E).

10. The turbine (110) according to any one of claims 1 to 9, comprising a second axial stop, the second axial stop being configured to axially lock the intermediate bushing (124) relative to the bearing (118) at a given stop axial position relative to the bearing (118) in a direction opposite to the restoring force (E) of the return device (160).

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