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 a main axis and having a hole arranged about and oriented parallel to the axis; - an annular bearing support extending about and at least partially about the main axis and about the ring, the support having a hole and an opening arranged about and oriented parallel to the axis; and - a series of studs for connecting the ring to the support, the studs being distributed about the main axis and having an elongated axis generally parallel to the main axis, each stud comprising a body having a first longitudinal end engaging in a hole in the ring and a second longitudinal end engaging in a hole in the support, the body of each stud passing through an opening in the opening of the support, some studs passing through the first opening with a positive first gap and a nearly zero second gap.

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) that 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 that allow for relaxation of the shaft's boundary conditions and reduction of the intrinsic mode frequencies. This allows the modes to be reduced below the operating range.

[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 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 includes 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.

[0010] In current technology, the main body has a circular cross-sectional shape, i.e., an axisymmetric shape (the cross-sectional shape of the main body of the stud is symmetrical with respect to the longitudinal axis of the main 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.

[0011] Prior art also includes techniques described by FR-A1-3 091 902, FR-A1-2 519 101, GB-A-2 3100 258, US-A1-2016 / 177765, US-A-3 357 757, or CN-B-103 244 276. This invention proposes an improvement to the second technique, which in particular enables the adjustment of the stiffness of the flexible cage 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 extends about the main axis and includes a hole arranged around and oriented parallel to the axis.

[0014] - A ring bearing support extending around a main axis and at least partially around a ring, the support including holes and openings arranged around and oriented parallel to the axis, and

[0015] - A series of studs for connecting the ring to the support, the studs being distributed around a main axis and having an elongated axis generally parallel to the main axis, each stud including a body comprising a first longitudinal end engaging in a hole in the ring and a second longitudinal end engaging in a hole in the support, the body of each stud passing through an opening in the support.

[0016] The feature is that the bodies of some studs, referred to as first studs, pass through a first opening with a positive first gap and a nearly zero second gap, the first gap being oriented in at least a first radial direction relative to the elongation axis, the second gap being oriented in at least a second radial direction relative to the elongation axis, the second radial direction being different from the first direction, the first gap and the second gap being configured such that the device has different displacement amplitudes in at least two directions perpendicular to the main axis.

[0017] Regardless of the position of the stud around its corresponding axis, a device equipped with a stud having an axisymmetric body, using the prior art, has 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).

[0018] Conversely, the present invention allows for different stiffnesses to be imparted to the device depending on the lateral direction of the load. Different radial orientations of the gaps between the studs and the openings of the supports mean that some studs respond to the load differently than others. Advantageously, the device incorporates two different stiffnesses in the lateral direction. Providing different stiffnesses in two mutually perpendicular lateral directions is particularly useful for shaft stability, as this allows for reducing the speed at which instabilities occur in the shaft guided by the device. The invention is advantageous because it allows for a variety of possible configurations while limiting the cost of the device, as a flexible cage is formed by assembling the studs. For example, in the case of an integral flexible cage, changes in characteristics would require the production of new components. This would mean additional costs and delays during the development phase, especially in the event of dimensional errors in the prototype components. The time required to produce new components is not compressible.

[0019] It should also be understood that the present invention covers all combinations of shapes for the cross-section of the stud and the opening of the support. These shapes can be selected from general cylindrical, oblong, elliptical, rectangular or trapezoidal shapes.

[0020] 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:

[0021] - The first and second directions are perpendicular to each other;

[0022] - The first and second directions are tangentially or normally oriented relative to the circumference centered on the main axis;

[0023] - The body of another stud, referred to as the second stud, passes through the second opening with a third gap, which is oriented in a second direction. The third gap is different from, and preferably substantially larger than, the first gap and the second gap of the first stud in the first opening.

[0024] -The first stud and the second stud alternate around the axis;

[0025] - The main body of the stud is roughly cylindrical;

[0026] - The cross-section of the first opening is oblong or elliptical, and the cross-section of the second opening is circular;

[0027] - The first opening is oriented such that the first opening has an elongated shape in the same direction;

[0028] - The opening is set in the annular wall of the support;

[0029] - 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.

[0030] The present invention also relates to an aircraft turbine engine comprising at least one device as described above. Attached Figure Description

[0031] 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:

[0032] [ 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;

[0033] [ Figure 2 ] Figure 2 This is a schematic axial cross-sectional view of another device for guiding and centering the bearings of an aircraft turbine engine, based on existing technology.

[0034] [ Figure 3 ] Figure 3 This is a very schematic cross-sectional view of a support member for a bearing guiding and centering device for an aircraft turbine engine according to an embodiment of the present invention;

[0035] [ Figure 4 ] Figure 4 yes Figure 3 A schematic axial section view of the device along section axis II;

[0036] [ Figure 5 ] Figure 5 yes Figure 3 A schematic axial section view of the device along section axis II-II;

[0037] [ Figure 6 ] Figure 6 yes Figure 3 A schematic axial section view of the device along section axis III-III. Detailed Implementation

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

[0039] 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.

[0040] The outer ring 12 is integrated into the inner cylindrical wall 10a of the cage frame 10, which includes a radially outer annular flange 10b for attachment to the support member 16 via a screw-nut type member (not shown).

[0041] The cage 10 includes two series of studs 20 and 22, which are radially inward and radially outward relative to the axis X of the bearing 14 and the shaft guided by the bearing, respectively.

[0042] Studs 20 and 22 are distributed around and extend parallel to axis X. Stud 20 extends around stud 22 and has a first longitudinal end and a second longitudinal end, the first longitudinal end being connected to flange 10b, and the second longitudinal end being connected to another stud 22 via an annular segment 24 of cage 10 having a C-shaped cross-section. Stud 22 extends from wall 10a (in its extension) to segment 24.

[0043] The support member 16 forms part of the stator of the turbine engine and has a generally truncated conical overall shape. At the inner periphery of the support member, it includes an inner cylindrical surface 16a for a contractile fit with an annular member 26 extending around the cage wall 10a, and together with the cage wall, defining an annular space 28 for supplying oil to form an oil film for damping vibrations transmitted through the bearing 14 during operation.

[0044] Figure 2 The second flexible cage 30 technology with independent studs 32 is shown according to the prior art.

[0045] The flexible cage 30 also ensures the connection between the outer ring 12 of the rolling bearing 14 and the annular support 16 of the bearing 14.

[0046] In addition to the outer ring 12, the bearing 14 also includes an inner ring 18 that is fixed to the shaft A of the turbine engine. Rings 12 and 18 define the roller raceways in the example shown.

[0047] The outer ring 12 includes a radially outer annular flange 12a which includes a hole through which the end 32a of the stud 32 passes. These ends 32a are threaded and receive nuts 34 which are fastened against the flange 12a.

[0048] The opposite end 32b of the stud 32 is attached in the aperture of the support 16.

[0049] The cage 30 includes a series of studs 32 which are distributed around an axis X and extend parallel to this axis. Each stud 32 includes a body 32c with a circular cross-section and the studs are thus symmetrical with respect to the axis Y of the stud. The studs 32 are also symmetrical with respect to each other around the axis X.

[0050] The flexible cage 30 is thus "axisymmetric" and the stiffness of the cage 10 and the bearing 14 is thus the same in all transverse directions (perpendicular to the axis X).

[0051] 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 of instability due to the internal damping of the shaft.

[0052] In fact, by creating different flexibilities in at least two directions, at least two modes occur instead of the single mode in the axisymmetric case.

[0053] In the case where the initial radial stiffness K of the axisymmetric 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 modes generated will be within the frequency of the initial single mode.

[0054] In this case, the frequency at which instability can occur is increased, thus allowing the risk of potentially damaging instability of the engine to be limited.

[0055] The control of the azimuthal movement of the shaft can also be used to improve the performance of the engine. Under mechanical or thermal loads, the engine casing deforms and these deformations produce different gap openings and closings depending on the azimuth. This means a degradation of the engine performance and this degradation can be limited if the dynamic displacements are optimized to compensate for some of the deformations, for example by stiffening the flexible cage in the direction of gap closing and softening the flexible cage in the direction of gap opening.

[0056] Figures 3 to 6 An embodiment of a device for centering and guiding the shaft of an aircraft turbine engine according to the invention is shown which makes it possible to meet this requirement.

[0057] The device comprises:

[0058] - The outer ring 12 of the rolling bearing 14 extends about the main axis X and includes holes 42a, 42b arranged about and oriented parallel to the axis X.

[0059] - An annular bearing support 16 extending around the main axis X and at least partially around the ring 12, the support 16 including holes 44a, 44b and openings 46a, 46b arranged around and oriented parallel to the axis X, and

[0060] - A series of studs 40, 41 for connecting the ring 12 to the support 16.

[0061] Studs 40, 41 are distributed around a main axis X and have an elongated axis Y that is generally parallel to the main axis X. Advantageously, each of these studs 40, 41 includes a generally cylindrical body 40c, 41c, which includes a first longitudinal end 40a, 41a and a second longitudinal end 40b, 41b. In another embodiment not shown, the bodies 40c, 41c of the studs 40, 41 may have a generally non-cylindrical shape (e.g., an oblong shape). Each of the first ends 40a, 41a is located in one of the holes 42a, 42b of the ring 12, and each of the second ends 40b, 41b engages in one of the holes 44a, 44b of the support 16. In particular, the first ends 40a, 41a and the second ends 40b, 41b may engage in the aforementioned holes without gaps. The body 40c, 41c of each of the studs 40, 41 passes through one of the openings 46a, 46b in the support 16. These openings 46a, 46b may be provided in the generally radial annular wall 16d of the support 16. It should be understood that the openings 46a, 46b are axially aligned with the holes 42a, 42b in the ring 12 and the holes 44a, 44b in the support 16.

[0062] The first stud 41 and the second stud 40 can be distinguished from studs 40 and 41. The first opening 46b and the second opening 46a can also be distinguished from openings 46a and 46b. The first stud 41 has a body 41c that passes through the first opening 46b in the support member 16 with a positive (greater than zero) first gap 411 and a nearly zero second gap 412. The second stud 40 has a body 40c that passes through the second opening 46a in the support member 16 with a third gap 403.

[0063] The first gap 411 is oriented in at least a first direction D1 radially relative to the elongation axis Y. The second gap 412 is oriented in at least a second direction D2 radially relative to the elongation axis Y, which is different from the first direction D1. The first gap 411 and the second gap 412 are configured such that the device has different ranges of motion in at least two different directions perpendicular to the main axis X. The third gap 403 is different from the first gap 411 and the second gap 412 in the first opening 46b of the first stud 41. Preferably, the third gap 403 is substantially larger than the first gap 411 and the second gap 412, and is oriented in the second direction D2 radially relative to the elongation axis Y.

[0064] Preferably, the first direction D1 and the second direction D2, which are perpendicular to the axis X, are perpendicular to each other. The first direction D1 and the second direction D2 can be tangentially or normally oriented relative to a circle centered on the main axis X.

[0065] exist Figure 3 In the example of the illustrated embodiment, first studs 41 and second studs 40 alternate around the main axis X. It should be understood that at least one first stud 41 may be positioned between two second studs 40 around the axis X, and at least one second stud 40 may be positioned between two first studs 41 around the axis X. In other words, the number of first studs 41 between two second studs 40 may be different from one. The number of second studs 40 between two first studs 41 may also be different from one.

[0066] Advantageously, the first ends 40a, 41a of the studs 40, 41 have a generally circular cross-section. Advantageously, the second ends 40b, 41b also have a generally circular cross-section. In another embodiment not shown, the first ends 40a, 41a and the second ends 40b, 41b may have a generally non-circular (e.g., oblong) cross-sectional shape.

[0067] The axial cross-section of the ring 12 is generally L-shaped, and the ring includes a cylindrical portion 12b, one axial end of which is connected to a radially outer annular flange 12a for attaching studs 40, 41.

[0068] The cylindrical portion 12b of the ring 12 includes an annular groove 12c at its inner periphery and an outer cylindrical surface 12d at its outer periphery. The annular groove is used to roll the balls of the bearing 14. The outer cylindrical surface, together with the support 16, defines an annular space for forming a damping oil film.

[0069] Support member 16 is partially shown in the accompanying drawings.

[0070] The support 16 includes a first cylindrical wall 16b that extends around the cylindrical portion 12b of the ring 12 and includes an inner cylindrical surface 16a that, together with the surface 12d, defines the aforementioned space for forming a damping oil film.

[0071] The support 16 includes a second cylindrical wall 16c extending around a first cylindrical wall 16b or even around a flange 12a of the ring 12. The first cylindrical wall 16b and the second cylindrical wall 16c are joined together by a generally radially extending annular wall 16d, which includes openings 46a, 46b through which the bodies 40c, 41c of studs 40, 41 pass. In the example shown, studs 40, 41 pass through an annular space formed between walls 16b, 16c. Wall 16d is located at one axial end of this space. The support 16 also includes an annular flange 16e.

[0072] Advantageously, openings 46a, 46b include a first opening 46b with a generally oblong or elliptical cross-section and a second opening 46a with a generally circular cross-section. The first opening 46b may preferably be elongated in the same direction. In another embodiment not shown, the cross-section of the first opening 46b may be generally circular, and the cross-section of the second opening 46a may be generally non-circular, such as oblong or elliptical. Thus, when the non-cylindrical (e.g., oblong) shaped bodies 40c, 41c of studs 40, 41 engage in one of the first openings 46b with a circular cross-section, studs 40, 41 may have a positive first gap and a nearly zero second gap as described above. Similarly, when the non-cylindrical (e.g., oblong) shaped bodies 40c, 41c of studs 40, 41 engage in one of the second openings 46a with a non-circular (e.g., oblong) cross-section, studs 40, 41 may have a third gap that is substantially larger than the first and second gaps.

[0073] like Figure 4 As shown, where, Figure 4 The device is shown along Figure 3 The axial cross-sectional view of the cutting axis II shown indicates that the body 40c of the second stud 40 can pass through the second opening 46a in the annular wall 16d of the support 16 with a third gap 403. This third gap 403 is oriented in all radial directions relative to the axis Y. It should be understood that the diameter of the opening 46a is larger than the diameter of the body 40c of the second stud 40.

[0074] like Figure 5 and Figure 6 As shown, where, Figure 5 and Figure 6 The device is shown along... Figure 3The axial cross-sectional views of section axes II-II and III-III shown indicate that the body 41c of the first stud 41 can pass through the first opening 46b in the annular wall 16d of the support 16 with a positive first gap 411 and a nearly zero second gap 412. Figure 6 The first gap 411, visible as a positive number, is oriented in a first direction D1 radially relative to the axis Y, which itself is tangentially or normally oriented relative to a circumference centered on the axis X. Figure 5 The nearly zero second gap 412, visible in the image, is oriented in a second radial direction D2 relative to the elongation axis Y. This second direction D2 is itself oriented tangentially or normally relative to a circumference centered on the axis X, and differs from the first direction D1. It should be understood that the elongated shape of the first opening 46b means that the first opening has a first longitudinal dimension larger than the second dimension, which is substantially perpendicular to the first dimension. It should also be understood that the first longitudinal dimension is larger than the diameter of the body 41c of the stud 41, and the second dimension is substantially equal to the diameter of the body 41c. In other words, the first stud 41 moves only in a certain amount in the longitudinal direction, which corresponds to the first direction D1, and is oriented tangentially or normally relative to a circumference centered on the axis X.

[0075] The cross-sections of holes 42a and 42b in ring 12 and holes 44a and 44b in support member 16 are approximately circular. This allows the ends 40a and 40b of studs 40 and 41 to engage seamlessly in ring 12 and support member 16, as shown below. Figures 4 to 6 As shown.

[0076] Holes 42a and 42b can be provided in flange 12a. Hole 42a passes through end 40a of stud 40, and hole 42b passes through end 41a of stud 41. These ends 40a and 41a can be threaded and receive nuts 43 fastened against flange 12a.

[0077] Holes 44a and 44b can be provided in flange 16e. Hole 44a passes through end 40b of stud 40, and hole 44b passes through end 41b of stud 41. These ends 40b and 41b can be threaded and receive nuts 45 fastened against flange 16e.

[0078] The bodies 40c and 41c of each stud 40 and 41 can be connected to each of the ends 40a, 40b, 41a, and 41b via annular collars 40d and 41d. The collars 40d and 41d may include flat regions that can be supported on the flange 16e of the support 16 and the flange 12a of the ring 12, respectively, thereby preventing rotation of the studs 40 and 41 about their longitudinal axes.

[0079] exist Figure 3 In the example shown, the cage allows for non-axisymmetric displacement of studs 40 and 41. The displacement allowed under a first lateral load (arrow F1) is greater than the displacement allowed under a second load (arrow F2) perpendicular to the first load. Therefore, the stiffness of the cage under the first load will be lower than that under the second load. When the cage is subjected to the first load (arrow F1), all studs 40 and 41 can deform in the direction of the first load (arrow F1) within the gap between openings 46a and 46b, while the bodies 40c and 41c do not abut against the inner walls of openings 46a and 46b.

[0080] When the cage is loaded with a second load (arrow F2) perpendicular to the first load (arrow F1), the deformation effect allowed by the gap 403 oriented in all radial directions of the second opening 46a is reduced due to the presence of a nearly zero second gap 412 in the direction parallel to the second load (arrow F2) of the first opening 46b. In this direction, the first stud 41 cannot deform and abuts against the inner wall of the first opening 46b.

[0081] The present invention also relates to an aircraft turbine engine comprising at least one device as described above.

[0082] 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.

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 (14) extends about the main axis (X) and includes a first hole (42a, 42b) arranged about the main axis and oriented parallel to the main axis. - An annular bearing support (16) extending around the main axis (X) and at least partially around the outer ring (12), the annular bearing support including a second hole (44a, 44b) arranged around and oriented parallel to the main axis, a first opening (46b) and a second opening (46a), and - A series of studs (40, 41) for connecting the outer ring to the annular bearing support, the studs being distributed around the main axis (X) and having an elongated axis (Y) parallel to the main axis (X), each of the studs including a first body (41c) or a second body (40c), the first body or the second body including a first longitudinal end (40a, 41a) engaging in one of the first holes (42a, 42b) of the outer ring and a second longitudinal end (40b, 41b) engaging in one of the second holes (44a, 44b) of the annular bearing support, the first body or the second body of each stud passing through one of the first opening (46b) and the second opening (46a) of the annular bearing support. The device is characterized in that the first body (41c) of some studs (40, 41) referred to as the first stud (41) passes through the first opening (46b) with a positive first gap (411) and a nearly zero second gap (412), the first gap (411) being oriented in at least a first direction (D1) radially relative to the elongation axis (Y), and the second gap (412) being oriented in at least a second direction (D2) radially relative to the elongation axis (Y), the second direction being different from the first direction, the first gap (411) and the second gap (412) being configured such that the device has different displacement amplitudes in at least two directions perpendicular to the main axis.

2. The apparatus according to claim 1, wherein, The first direction (D1) and the second direction (D2) are perpendicular to each other.

3. The apparatus according to claim 1 or 2, wherein, The first direction (D1) and the second direction (D2) are tangentially or normally oriented relative to a circumference centered on the main axis (X).

4. The apparatus according to claim 1 or 2, wherein, The second body (40c) of the other studs, referred to as the second stud (40), passes through the second opening (46a) with a third gap (403), the third gap being oriented in the second direction, the third gap (403) being different from the first gap (411) and the second gap (412) of the first stud (41) in the first opening (46b).

5. The apparatus according to claim 4, wherein, The first stud (41) and the second stud (40) alternate around the main axis.

6. The apparatus according to claim 4, wherein, The first opening (46b) has an oblong or elliptical cross-section, and the second opening (46a) has a circular cross-section.

7. The apparatus according to claim 6, wherein, The first opening (46b) is oriented such that the first opening has an elongated shape in the same direction.

8. The apparatus according to claim 1 or 2, wherein, The cross-sections of the first body (41c) and the second body (40c) are cylindrical.

9. The apparatus according to claim 1 or 2, wherein, The first opening (46b) and the second opening (46a) are provided in the annular wall (16d) of the annular bearing support (16).

10. The apparatus according to claim 1 or 2, 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 for forming a damping oil film.

11. The apparatus according to claim 4, wherein, The third gap (403) is greater than the first gap (411) and the second gap (412) of the first stud (41) in the first opening (46b).

12. An aircraft turbine engine comprising at least one device according to any one of claims 1 to 11.

Images