Device for centering and guiding a shaft of a turbine engine of an aircraft

Abstract

This invention relates to a device for centering and guiding the shaft of an aircraft turbine engine, the device comprising: - an outer ring of a rolling bearing extending about an axis; - an annular bearing support extending about the axis and at least partially about the ring; - at least one series of connecting elements for connecting the ring to the support, the elements being elastically deformable and distributed about the axis with an inclination relative to the radial direction specific to each element; the connecting elements being inserted between an inner cylindrical edge of the ring and an outer cylindrical edge of the support, the outer cylindrical edge extending about an inner edge; each connecting element including a first radially outer end for connecting to the outer cylindrical edge and a second radially inner end for connecting to the inner cylindrical edge; the ring, the support, and the connecting elements being integrally formed; the connecting elements being enclosed in an annular configuration defined radially by the edges and laterally closed by an annular connecting plate, the annular connecting plate being elastically deformable and connecting the edges.

Description

Technical Field

[0001] The present invention relates to a device for centering and guiding the shaft of an aircraft turbine engine. Background Technology

[0002] Aircraft turbine engines include shafts (such as low-pressure shafts and high-pressure shafts), which are centered and guided to rotate by bearings, which are typically rolling bearings, such as roller bearings or ball bearings.

[0003] A rolling bearing consists of an outer ring and an inner ring, with rollers or balls arranged between them. The inner ring is fixed to the shaft to be guided, and the outer ring is attached to a bearing support, which is a rigid component of the turbine engine stator.

[0004] The shaft of a turbocharged engine can reach very high speeds, typically between 2,000 rpm and 30,000 rpm. These speeds excite the intrinsic modes of the shaft, and if the modal response is strong, this can have a detrimental effect on the engine.

[0005] To control the position of the modes, bearings are typically combined with flexible cages, which allow for relaxation of the shaft's boundary conditions and reduction of the intrinsic mode frequencies. Lower-velocity modes exhibit weaker responses.

[0006] In this application, "flexible cage" refers to a component or assembly that provides a flexible connection between the outer ring of a bearing and the bearing's support. The flexibility of the cage is typically ensured by its ability to elastically deform, for example, during torsion and / or bending. To provide this capability, the cage includes at least one series of studs distributed around and extending substantially parallel to the axis of the bearing.

[0007] There are currently two flexible cage technologies used for bearings.

[0008] The first technology described in documents FR-A1-3 009 843 and FR-A1-3 078 370 is an integral flexible cage. This type of cage typically comprises an inner cylindrical wall and an outer cylindrical wall or attachment flange, to which the outer ring of the bearing is attached or integrated, and the outer cylindrical wall or attachment flange is used to attach to the bearing support. These walls are connected by a series of generally C-shaped or L-shaped studs or by two series of studs extending around each other and connected together. The studs and walls are then formed as a single piece.

[0009] The second technique described in document FR-A1-3 009 843 involves a cage obtained by assembling individual studs with supports and rings. Each stud comprises an elongated body and is connected at a first longitudinal attachment end for attachment to the support and a second longitudinal attachment end for attachment to the ring. The cross-sectional shape of the body is circular, i.e., axisymmetric (the cross-sectional shape of the stud body is symmetrical with respect to the longitudinal axis of the body). The flexible cage equipped with these studs also has an axisymmetric shape, and the stiffness of the cage is the same regardless of the lateral direction of the load force on the cage.

[0010] The prior art also includes the techniques described by US-B1-10 794 222, DE-A4-10 2017 100572, FR-A1-3 096072 or DE-A1-10 2012 221369.

[0011] This invention proposes improvements to these techniques, which in particular enable the stiffness of the flexible cage to be adjusted according to changes in the direction of the load. Summary of the Invention

[0012] This invention proposes a device for centering and guiding the shaft of an aircraft turbine engine, the device comprising:

[0013] - The outer ring of the rolling bearing, which extends around the axis.

[0014] - A ring bearing support extending around the axis and at least partially around the ring, and

[0015] - At least one series of connecting elements for connecting the ring to the support, these elements being elastically deformable and distributed about an axis with an inclination relative to the radial direction specific to each element, the connecting elements being inserted between the inner cylindrical edge of the ring and the outer cylindrical edge of the support, the outer cylindrical edge extending around the inner edge, and each connecting element including a first radially outer end portion for connecting to the outer cylindrical edge and a second radially inner end portion for connecting to the inner cylindrical edge.

[0016] The ring, support, and connecting elements are formed into a single unit.

[0017] The characteristic feature is that the connecting element is enclosed in an annular configuration defined radially by the edge, the annular configuration being laterally enclosed by an elastically deformable annular connecting plate that connects the edges and forms an integral part with the ring and the support.

[0018] Rings, supports, and connecting elements are formed from a single piece, for example, through additive manufacturing. This simplifies the manufacture of the device by eliminating assembly and adjustment steps. The distribution of these connecting elements around the device, and the tilt of each element relative to the radial direction, make it possible to adjust the stiffness of the device in these directions.

[0019] Regardless of the position of the stud around its corresponding axis, prior art devices equipped with studs having an axisymmetric body have the same stiffness in all lateral directions (perpendicular to the axis). This means that the stiffness of the device in a first direction perpendicular to the axis (e.g., in a horizontal plane) is the same as the stiffness of the device in a second direction perpendicular to the axis (e.g., in a vertical plane).

[0020] Conversely, the present invention enables the device to be given different stiffnesses depending on the lateral direction of the load. Advantageously, the device includes at least two different stiffnesses in the lateral direction relative to the axis of the shaft. Providing different stiffnesses in two mutually perpendicular lateral directions is particularly useful for stabilizing the shaft, as this allows for the reduction of the speed at which instability occurs in the shaft guided by the device.

[0021] The apparatus according to the invention may include one or more of the following features, which may be employed independently of each other or in combination with each other:

[0022] - The outer ring includes an outer cylindrical surface that, together with the inner cylindrical surface of the support, defines an annular space for forming a damping oil film.

[0023] - The connecting element is located at one axial end of the annular space and on a circumference having a diameter that is substantially equal to the diameter of the space.

[0024] - Connecting elements are distributed around the axis with regular and / or irregular spacing;

[0025] - The connecting element is formed from blades;

[0026] - The blades have a roughly wavy shape;

[0027] - Each leaf is roughly S-shaped;

[0028] - The connecting plate is roughly corrugated pipe shaped;

[0029] - The first series of blades and the first connecting plate are located at one axial end of the device, and the second series of blades and the second connecting plate are located at opposite axial ends of the device;

[0030] - The first and second connecting plates form a lateral seal for the annular space, and the support includes at least one supply hole and at least one hole for discharging oil from the space.

[0031] The present invention also relates to an aircraft turbine engine comprising at least one device as described above. Attached Figure Description

[0032] Other features and advantages of the invention will become apparent from the following detailed description, and with reference to the accompanying drawings for understanding the description, in which:

[0033] [ Figure 1 ] Figure 1 It is a schematic axial cross-sectional perspective view of a device for guiding and centering the bearings of an aircraft turbine engine, based on existing technology;

[0034] [ Figure 2 ] Figure 2 This is a schematic perspective view of a device for guiding and centering the bearings of an aircraft turbine engine according to an embodiment of the present invention;

[0035] [ Figure 3 ] Figure 3 yes Figure 2 A schematic cross-sectional half-view;

[0036] [ Figure 4 ] Figure 4 yes Figure 3 A very schematic cross-sectional view;

[0037] [ Figure 5 ] Figure 5 This is a schematic perspective view of a device for guiding and centering the bearings of an aircraft turbine engine according to another embodiment of the present invention, showing the axial end of the device in a transparent view. Detailed Implementation

[0038] First refer to Figure 1 The figure illustrates the first integral flexible cage 10 technology according to the prior art.

[0039] The flexible cage 10 ensures the connection between the outer ring 12 of the rolling bearing 14 and the annular support 16 of the bearing 14.

[0040] In addition to the outer ring 12, the bearing 14 also includes an inner ring 18 that is fixed to the shaft (not shown) of the turbine engine. Rings 12 and 18 define the roller raceways in the example shown.

[0041] The outer ring 12 is integrated into the inner cylindrical wall 10a of the cage 10, which includes a radially outer annular flange 10b for attachment to a support 16 by means of a screw-nut type member (not shown).

[0042] The cage 10 includes two series of studs 20, 22, which are respectively radially inward and radially outward with respect to the axis X of the bearing 14 and the shaft guided by this bearing. The axis X corresponds to the engine axis of the turbomachine.

[0043] The studs 20, 22 are distributed around the axis X and extend parallel to this axis. The stud 20 extends around the stud 22 and has a first longitudinal end in the longitudinal ends of the stud and a second longitudinal end in the longitudinal ends of the stud. The first longitudinal end is connected to the flange 10b, and the second longitudinal end is connected to another stud 22 through an annular section 24 of the cage 10 having a C-shaped cross-section. The stud 22 extends from the wall 10a in line with it to the section 24.

[0044] The support 16 forms part of the stator of the turbomachine and has here an overall shape that is generally frustoconical. On the inner periphery of the support, the support includes an inner cylindrical surface 16a for shrink-fitting an annular piece 26 that extends around the wall 10a of the cage, and this annular piece together with the wall of the cage defines an annular space 28 for supplying oil to form an oil film for damping vibrations transmitted through the bearing 14 during operation.

[0045] In this type of technology, the stiffness of the cage 10 and the bearing 14 is the same in all transverse directions (perpendicular to the axis X).

[0046] However, from a dynamic point of view, it may be interesting to have different stiffnesses in two orthogonal directions: this provides a stabilizing effect for the device by delaying the onset speed of instability due to the internal damping of the shaft.

[0047] In fact, by generating different flexibilities in at least two directions, at least two modes appear instead of a single mode in the case of axial symmetry.

[0048] In the case where the initial radial stiffness K of the axially symmetric cage is such that K1 < K < K2, where K1 and K2 are the stiffnesses of the asymmetric flexible cage in different directions 1 and 2 transverse to the axis X respectively, the frequencies of the generated modes will be within the frequency of the initial single mode.

[0049] In this case, the frequency at which instability can occur is increased, thus allowing the risk of potential destructive instability of the engine to be limited.

[0050] Controlling the movement of the shaft in the azimuth angle can also be used to improve engine performance. Under mechanical or thermal loads, the engine casing deforms, and these distortions produce different gap openings and closures depending on the azimuth angle. This means a decrease in engine performance, which can be limited if dynamic displacement is optimized to compensate for some of the distortion, for example by stiffening the flexible cage in the gap closure direction and softening it in the gap opening direction.

[0051] The present invention enables this requirement to be met by means of a connecting element for connecting the ring 12 to the support 16, the connecting element being integral with the ring and the support.

[0052] Figures 2 to 4 An embodiment of a device according to the invention for centering and guiding the shaft of an aircraft turbine engine is shown. The device is symmetrical with respect to a mid-plane P perpendicular to the axis X, as shown below. Figure 2 As shown. This means that the device comprises two identical axial ends. In other words, the following description of one axial end of the device also applies to the other axial end opposite the first axial end.

[0053] The device includes:

[0054] - The outer ring 12 of the rolling bearing extends about axis X.

[0055] -A ring bearing support 16 extending around axis X and at least partially around ring 12, and

[0056] - At least one series of connecting elements 40 for connecting the ring 12 to the support 16, the elements 40 being distributed around the axis X, and each element including a first end 40a for connecting to the support 16 and a second end 40b for connecting to the ring 12.

[0057] The ring 12, support 16, and connecting element 40 are formed as a single piece. In other words, the device is integral. Unlike the prior art flexible cage 10 (in which only the studs 20, 22, walls 10a, and flanges 10b are formed as a single piece), the support 16 is also formed as a single piece with the ring 12 and element 40.

[0058] The outer ring 12 includes a cylindrical portion 12b with an outer cylindrical surface 12d at its outer periphery, which, together with the support 16, defines an annular space 50 for forming a damping oil film. The ring 12 also includes, at each of its ends, an inner cylindrical edge 12c extending in the axial extension of the cylindrical portion 12b. The inner cylindrical edge 12c is understood to refer to an edge extending as close as possible to the axis X in the axial extension of the ring 12. The thickness of the edge 12c is less than the thickness of the cylindrical portion 12b of the ring 12.

[0059] The support 16 includes a cylindrical portion 16b that extends at least partially around the cylindrical portion 12b of the ring 12. The cylindrical portion 16b includes an inner cylindrical surface 16a at its inner periphery, which, together with the outer cylindrical surface 12d, defines the aforementioned annular space 50 for forming a damping oil film.

[0060] The support member 16 includes at least one oil supply hole 52 and at least one oil discharge hole, each of which communicates with the annular space 50. These holes are located on the outer periphery of the cylindrical portion 16b. The supply hole 52 leads to a first annular groove (not visible here), which ensures uniform distribution of oil within the annular space 50. In the presence of multiple supply holes 52, multiple first annular grooves ensure oil distribution.

[0061] The support member 16 also includes, at each of its ends, an outer cylindrical edge 16c that extends in the axial extension of the cylindrical portion 16b and around the inner edge 12c. The outer cylindrical edge 16c is understood to refer to an edge extending as far away as possible from the axis X in the axial extension of the support member 16. The thickness of edge 16c is less than the thickness of the cylindrical portion of the support member 16.

[0062] Furthermore, the inner cylindrical edge 12c can be referred to as the first cylindrical edge 12c, and the outer cylindrical edge 16c can be referred to as the second cylindrical edge 16c.

[0063] Connecting element 40 is located at one axial end of an annular space 50. The connecting element lies on a circumference C1 having a diameter substantially equal to the diameter of space 50. This means that the geometric center of each of the elements 40 lies on this circumference C1. It should be understood that a portion of the shape of element 40 may lie outside this circumference C1; in other words, a portion of element 40 may lie on a circumference having a diameter substantially larger or smaller than the diameter of circumference C1.

[0064] In the example shown here, the connecting element 40 is elastically deformable and can be formed of blades, which are themselves elastically deformable. The blades are defined as thin, long strips, the thickness of which is less than the width of which extends generally parallel to the axis X. The blades are inserted between the inner cylindrical edge 12c of the ring 12 and the outer cylindrical edge 16c of the support 16. Specifically, each of the blades is connected to the edge 16c of the support 16 via its first radially outer end 40a and to the edge 12c of the ring 12 via its second radially inner end 40b.

[0065] The connecting element 40 is enclosed within an annular receiving portion 60. This receiving portion 60 is radially defined by an inner cylindrical edge 12c and an outer cylindrical edge 16c, and laterally enclosed by the combined allowance of the cylindrical portions 12b and 16b and an annular connecting plate 62, with an annular space 50 extending between the cylindrical portions 12b and 16b. The connecting plate 62 is understood to be thin-walled, specifically, its thickness is less than the thickness of the edges 12c and 16c, and it engages the edges 12c and 16c by forming an integral part with the ring 12 and the support member 16. The connecting plate 62 is elastically deformable and can be corrugated in the radial direction. For example, the connecting plate 62 can adopt the overall shape of a bellows, or its cross-section can be Ω-shaped.

[0066] This shape allows the connecting plate 62 to absorb relative displacement between the ring 12 and the support 16 in the axial direction. The connecting plate 62 also has the advantage of providing a lateral seal for the annular space 50 where the damping oil film is formed. Since the connecting plate 62 is integral with the ring 12 and the support 16, oil cannot escape laterally from the device.

[0067] It should be understood that the receiving portion 60 can contain oil from the annular space 50. In other words, the connecting element 40 can be immersed in oil.

[0068] At least one oil discharge orifice (not shown) may be present in the receiving portion 60. This orifice is calibrated to discharge oil from the receiving portion 60 at a flow rate equal to the oil flow rate required to form a damping oil film in the annular space 50. Furthermore, to ensure better discharge, these orifices may open to a second annular groove.

[0069] In a variant not shown here, the annular segment axially defines the annular space 50. It should be understood that only the annular space 50 contains oil. Each segment includes a calibrated leak to discharge oil from the annular space 50 at a flow rate substantially lower than the supply flow rate to the annular space 50. This leak is calibrated to have a flow rate substantially lower than the discharge flow rate through the discharge orifice in the receiving portion 60. Oil is discharged through a lower outlet.

[0070] exist Figure 3 and Figure 4 In the example shown, each blade has a generally “S” shape. This shape has the advantage of having bends 41a and 41b at the level of the blade ends 40a and 40b. The first bend 41a at the level of the first end 40a is oriented in a first orientation, and the second bend 41b at the level of the second end 40b is oriented in a second orientation opposite to the first orientation.

[0071] The “S” shape also has the advantage of having a center of symmetry. This center of symmetry corresponds to the geometric center of the shape and is located approximately on the circumference C1. Thus, the first joint between the first end 40a and the support 16 is symmetrical with respect to this center of symmetry to the second joint between the second end 40b and the ring 12. Furthermore, the first joint, the second joint, and the center of symmetry, all located in the same plane, are radially aligned with the center of the device through which the axis X passes.

[0072] Another advantage of the “S” shape is that it imparts at least two different stiffnesses to element 40 depending on the direction of the load. In fact, under a load known as a vertical load, i.e., in the direction tangential to the bends 41a and 41b, element 40 can deform. The bends 41a and 41b ensure the flexibility of element 40. Under a load known as a horizontal load perpendicular to the vertical load, element 40 does not deform.

[0073] The “S” shape is unrestricted, and the blades can adopt any shape that provides different stiffness in two directions in a plane orthogonal to the axis of rotation of the engine shaft (in other words, axis X).

[0074] Connecting elements 40 or blades are arranged around axis X. The connecting elements or blades can be distributed at a regular spacing, meaning the distance between two consecutive elements 40 is the same. The connecting elements or blades can also be distributed at an irregular spacing, meaning the distance between elements 40 can vary. In a non-limiting example, there can be a first group of elements 40 and a second group of elements 40, with the first group of elements spaced apart from each other at the same distance or the same spacing, and the second group of elements spaced apart from each other at the same distance but at a different distance from the first group of elements. This means that the spacing between elements 40 can be regular and / or irregular.

[0075] The device can be manufactured using additive manufacturing. This can be, for example, metal additive manufacturing via powder sintering. Because the device can include components 40 with specific configurations, this technology particularly simplifies device production by eliminating assembly and adjustment steps. Furthermore, this means that the configuration of components can be easily and quickly changed during the development phase.

[0076] Figure 4A cross-section of a section of the device is shown. A group of elements 40 are distributed around axis X. It should be understood that the cage 10 is not axisymmetric with respect to axis X, and the stiffness of the cage is also not axisymmetric. Each of the elements 40 is arranged at a given angle relative to the radial direction. In other words, each element 40 has its own inclination relative to the radial direction. Thus, when the device is loaded in a first direction (arrow F1) or a second direction orthogonal to the first direction (arrow F2), total stiffness is obtained. The first direction may be, for example, vertical, and the second direction orthogonal to the first direction may be, for example, horizontal. Due to this given inclination, it should be understood that each element 40 deforms differently depending on the load F1 or F2 and has its own specific stiffness. In this way, all the elements 40 work together, thereby making it possible to limit stress concentration.

[0077] Figure 5 Another example of an embodiment of the device is shown. In this example, the device is similar to the device described above. The device includes a first set of elements 40 and a second set of elements 40'. The second set of elements 40' is symmetrical to the first set of elements 40 with respect to the plane of symmetry A. Although not shown here, the device may also include two additional sets of elements 40, 40': a third set of elements 40' and a fourth set of elements 40. The third set of elements 40' may be positioned relative to the first set of elements 40 with respect to the plane of symmetry B. It is understood that the third set of elements is the same as the second set of elements. The fourth set of elements 40 may be positioned relative to the plane B with respect to the second set of elements 40', and the fourth set of elements is symmetrical to the second set of elements. It should be understood that the fourth set of elements is also symmetrical to the third set of elements with respect to the plane A, and it should also be understood that the fourth set of elements is the same as the first set of elements 40.

[0078] For each group of components 40, 40', a first given spacing separates components 40, 40'. It should be clear that this first spacing is the same for each group of components. A second spacing, different from the first spacing, separates each group of components. This second spacing can be smaller or larger than the first spacing.

[0079] The present invention also relates to an aircraft turbine engine comprising at least one device as described above.

[0080] Therefore, the advantage of the device and flexible cage according to the invention is that the stiffness of the cage varies depending on the angular position of the force transmitted to the cage in the direction transverse to the main axis of the cage.

[0081] To stabilize the shaft, it is particularly useful to provide different stiffnesses in different lateral directions, as this makes it possible to reduce the speed at which instability occurs in the shaft guided by the device.

Claims

1. A device for centering and guiding the shaft of an aircraft turbine engine, the device comprising: - The outer ring (12) of the rolling bearing extends about the axis (X), - A ring bearing support (16) extending around the axis (X) and at least partially around the outer ring (12). - At least one series of connecting elements (40) for connecting the outer ring to the annular bearing support, the connecting elements being elastically deformable and distributed around the axis (X) with an inclination relative to the radial direction specific to each connecting element, the connecting elements being inserted between the inner cylindrical edge (12c) of the outer ring (12) and the outer cylindrical edge (16c) of the annular bearing support (16), the outer cylindrical edge extending around the inner cylindrical edge, and each connecting element including a first radially outer end portion (40a) for connecting to the outer cylindrical edge and a second radially inner end portion (40b) for connecting to the inner cylindrical edge. The outer ring, the annular bearing support, and the connecting element are formed as a single unit. The connecting element (40) is characterized in that it is enclosed in an annular positioning portion (60) radially defined by the inner cylindrical edge (12c) and the outer cylindrical edge (16c), the annular positioning portion being laterally enclosed by an elastically deformable annular connecting plate (62), the annular connecting plate connecting the inner cylindrical edge (12c) and the outer cylindrical edge (16c) and forming an integral part with the outer ring (12) and the annular bearing support (16).

2. The apparatus of claim 1, wherein, The outer ring (12) includes an outer cylindrical surface (12d), which together with the inner cylindrical surface (16a) of the annular bearing support (16) defines an annular space (50) for forming a damping oil film.

3. The apparatus according to claim 2, wherein, The connecting element (40) is located at the axial end of the annular space (50) and on a circumference (C1) having a diameter equal to the diameter of the annular space.

4. The apparatus according to any one of claims 1 to 3, wherein, The connecting element (40) is formed of a blade.

5. The apparatus according to claim 4, wherein, Each of the blades is S-shaped.

6. The apparatus according to claim 4, wherein, The first series of blades and the first connecting plate are located at one axial end of the device, and the second series of blades and the second connecting plate are located at opposite axial ends of the device.

7. The apparatus according to claim 2 or 3, wherein, The first series of blades and the first connecting plate are located at one axial end of the device, and the second series of blades and the second connecting plate are located at opposite axial ends of the device. The first connecting plate and the second connecting plate form a lateral seal for the annular space (50). The annular bearing support includes at least one supply hole (52) and at least one discharge hole for discharging oil from the annular space.

8. The apparatus according to any one of claims 1 to 3, wherein, The annular connecting plate (62) is corrugated.

9. An aircraft turbine engine comprising at least one device according to any one of claims 1 to 8.

Images