Turbine engine bearing provided with a mechanical shim

Abstract

The present disclosure relates to a turbine engine assembly comprising: - a bearing; - an annular connector configured to connect an outer ring to a support, wherein the annular connector comprises a first flange and a second flange, wherein the second flange is arranged around and radially outside the first flange and comprises bores for attachment to the support, wherein the first flange is formed by a plurality of arms arranged side by side along the circumference of the connector, and wherein each arm of the first flange comprises a first end and a second end, and connected end to end, from the first end to the second end, a first section extending axially from the outer ring, a second section extending radially from the first section, and then a third section extending axially from the second section towards the second flange; and - a mechanical shim.

Description

[0001] DESCRIPTION

[0002] Turbomachine bearing equipped with a mechanical shim

[0003] TECHNICAL FIELD

[0004] This presentation concerns the field of turbomachines, in particular for aircraft and more particularly the field of devices for centering and guiding in rotation a rotating part of a turbomachine comprising a rolling bearing.

[0005] More specifically, this disclosure relates to devices whose rolling bearing comprises a flexible elastic part intended to provide radial suspension. Such a bearing is called a flexible bearing.

[0006] STATE OF THE ART

[0007] A turbomachine fan shaft rotates around an axis of rotation and requires a certain radial flexibility both in normal operation and in degraded operation, for example in the event of unbalance.

[0008] The fan shaft may be centered and rotationally guided by a device comprising a rolling bearing and a flexible bearing support, called a flexible bearing or flexible cage or squirrel cage. The device comprising the rolling bearing must allow radial flexibility. The flexible bearing includes arms suitable for allowing radial flexibility.

[0009] However, the rotation of the fan shaft can induce creep or ovalization phenomena which generate tangential stresses in the device and particularly in the arms of the flexible bearing. However, a relative tangential displacement in an arm of the flexible bearing can damage, or even break, the arm and thus generate a malfunction of the turbomachine.

[0010] It is therefore necessary to avoid such deterioration of the arm due to tangential stresses. But, it is also necessary not to limit the radial flexibility of the flexible bearing arms.

[0011] GENERAL STATEMENT

[0012] One aim of the presentation is to control the tangential displacements of the arms of a flexible bearing without limiting the radial displacements of the same arm.

[0013] To this end, according to one aspect of the present disclosure, a turbomachine assembly is proposed, comprising: a rolling bearing comprising an inner ring and an outer ring, an annular connection configured to connect the outer ring to a support, the annular connection comprising a first flange and a second flange, arranged around and radially outside the first flange and comprising holes for attachment to the support, the first flange being formed of several arms arranged side by side on the circumference of the connection, each arm of the first flange comprising a first end and a second end, and end to end from the first end to the second end, a first section extending axially from the outer ring, a second section extending radially from the first section, then a third section extending axially from the second section towards the second flange,and a mechanical wedge positioned between a first of the arms and a second of the adjacent arms and extending radially from the first end to the second end of the arms, opposite the second section relative to the first section and the third section, the mechanical wedge being suitable for preventing a relative tangential displacement between the first end and the second end of the arms greater than 3 mm by contact between the first of the arms and the second of the arms.,

[0014] Advantageously, but optionally, the assembly disclosed comprises at least one of the following characteristics, taken alone or in any combination:

[0015] - the mechanical shim includes fixing lugs to the fitting, the lugs being adapted to the holes in the second flange;

[0016] - the mechanical shim is suitable for allowing relative tangential movement between the first end and the second end of the arms up to 3 mm;

[0017] - the assembly comprises a plurality of mechanical shims positioned at regular intervals around the annular connection.

[0018] According to another aspect, there is provided a device for centering and guiding in rotation around an axis, a rotating part of a turbomachine, the device comprising: a turbomachine assembly as previously described, and a bearing support positioned radially outside the outer ring.

[0019] Advantageously, but optionally, the disclosed device may comprise the following characteristic: the annular assembly is suitable for being fixed to the support by screw elements and each mechanical wedge is fixed to the annular assembly by one or more of the screw elements for fixing the annular assembly to the support.

[0020] According to another aspect, there is provided an aircraft engine comprising: a fan shaft rotating about an axis, a device as previously described, capable of centering and guiding in rotation the fan shaft about the axis.

[0021] According to another aspect, there is provided an aircraft comprising an airframe and an engine as previously disclosed, wherein the engine is attached to the airframe.

[0022] DESCRIPTION OF FIGURES

[0023] Other characteristics, aims and advantages will emerge from the following description, which is purely illustrative and not limiting, and which must be read in conjunction with the attached drawings in which:

[0024] [Fig.1a] and [Fig.1b] illustrate aircraft, according to possible embodiments of the present disclosure;

[0025] Figure 2 illustrates a partial schematic sectional view of a turbomachine, according to an embodiment of the present disclosure;

[0026] Figure 3 illustrates a schematic view of a portion of a fan shaft and devices for guiding the shaft in rotation, according to an embodiment of the present disclosure;

[0027] Figure 4 illustrates a partial perspective view of a centering and rotational guidance device, according to an embodiment of the present disclosure;

[0028] Figure 5 illustrates a partial sectional view of a centering and rotational guidance device, according to an embodiment of the present disclosure;

[0029] Figure 6 illustrates a perspective view of a mechanical wedge, according to an embodiment of the present disclosure.

[0030] Throughout the figures, similar elements have identical references.

[0031] DETAILED DESCRIPTION

[0032] Aircraft

[0033] An aircraft 100 is an apparatus configured to rise and move through the air, and may, for example, be an airplane, as illustrated in FIGS. 1A and 1B, for example a civil airplane. An aircraft 100 comprises an airframe which, in the case of an airplane, is composed of a fuselage, a wing structure comprising two wings, empennages, flight control surfaces and landing gear.

[0034] Propulsion unit

[0035] A propulsion unit 1, as illustrated in FIG. 2, comprises an engine 2 and possibly a nacelle, and has a main direction extending along a longitudinal axis XX, or axis of rotation. The propulsion unit 1 is configured to be fixed to the airframe of the aircraft 100, for example under its wings, in the case of an airplane, and this by means of a pylon. The propulsion unit 1 can also be mounted on the wing of the airplane or at the rear of its fuselage, or even be integrated into its fuselage.

[0036] The engine 2 may be a ducted turbojet, or an unducted one as described below, with two spools, two-flow and direct drive, but may also have a different number of spools and / or flows, and / or be another type of turbojet, such as a geared turbojet or a turboprop, with or without afterburner.

[0037] Unless otherwise specified, the terms “upstream” and “downstream” are used with reference to the overall direction of airflow through the propulsion unit 1 in operation. Similarly, an axial direction corresponds to the direction of the longitudinal axis XX and a radial direction is a direction perpendicular to the longitudinal axis XX and intersecting the longitudinal axis XX. Furthermore, an axial plane is a plane containing the longitudinal axis XX and a radial plane is a plane perpendicular to the longitudinal axis XX. A circumference is understood to be a circle belonging to a radial plane and whose center belongs to the longitudinal axis XX. A tangential or circumferential direction is a direction tangent to a circumference: it is perpendicular to the longitudinal axis XX but does not pass through the longitudinal axis XX.Finally, the adjectives "inner" and "outer" are used in reference to a radial direction so that the inner part of an element is, in a radial direction, closer to the longitudinal axis XX than the outer part of the same element.

[0038] The engine

[0039] The engine 2 comprises, from upstream to downstream, a fan 20, a crankcase 21, a compressor section 22, comprising a low pressure compressor 220 and a high pressure compressor 221, a combustion chamber 23, a turbine section 24, comprising a high pressure turbine 240 and a low pressure turbine 241.

[0040] The compressor section 22 comprises a succession of stages each comprising a wheel of moving blades rotating in front of a wheel of fixed blades. The turbine section 24 also comprises a succession of stages each comprising a wheel of fixed blades behind which a wheel of moving blades rotates.

[0041] The fan 20 is connected to a shaft 25 extending along the longitudinal axis XX which drives it in rotation, as illustrated in FIG. 3. In one embodiment, the shaft 25 driving the fan 20, called the fan shaft 25, can be connected directly to the rotor part of the low-pressure compressor 220, and the rotor part of the low-pressure turbine 241, connected together, thus forming a low-pressure body, which is then referred to as a low-pressure shaft.In another embodiment, the fan shaft 25 can be connected to a reduction system 26, as illustrated in FIG. 2, the reduction system being further connected to the rotor part of the low-pressure compressor 220, and the rotor part of the low-pressure turbine 241, connected together, thus forming a low-pressure body, we then speak of fan shaft 25 for the shaft connecting the fan 20 to the reduction system 26 and of low-pressure shaft 27 for the shaft connecting the low-pressure body to the reduction system 26.

[0042] The rotor part of the high-pressure compressor 221 and the rotor part of the high-pressure turbine 240 are connected to each other by a high-pressure shaft 28 extending along the longitudinal axis XX, thus forming a high-pressure body. The low-pressure shaft 27 is generally housed, over a section of its length, in the high-pressure shaft 28 and is coaxial with the high-pressure shaft 28.

[0043] The compressor section 22, the combustion chamber 23 and the turbine section 24 are surrounded by the engine casing 21.

[0044] The engine casing 21 defines a primary flow path A in which the rotor and stator parts of the low-pressure compressor 220, the high-pressure compressor 221, the low-pressure turbine 241 and the high-pressure turbine 240 extend. The primary flow path A passes right through the engine casing 21. The stator parts in the primary flow path A can thus form rectifiers. In this way, the airflow circulating in the primary flow path A is deflected by the rotating rotor parts and is rectified by the stator parts fixed relative to the engine casing 21 defining the primary flow path A.

[0045] The longitudinal axis XX defines the axis of rotation for the fan 20, the rotor parts of the compressor section 22 and the rotor parts of the turbine section 24, in other words for the low-pressure body and the high-pressure body, each of which is capable of being driven in rotation about the longitudinal axis XX relative to the engine casing 21. In operation, the fan 20 draws in an air flow, a portion of which, circulating within a primary vein A passing right through the engine casing 21, is successively compressed within the compressor section 22, ignited within the combustion chamber 23 by combustion of fuel, and expanded within the turbine section 24 before being ejected from the engine 2. Another portion of the air flow can circulate within a secondary vein surrounding the engine casing 21. In this way, the propulsion unit 1 generates thrust.This thrust can, for example, be used for the benefit of the aircraft 100 on which the propulsion unit 1 is attached and fixed.

[0046] Thus, in operation, the fan 20 can rotate around its axis of rotation XX at high speed. It is therefore necessary to use a device for centering and guiding the fan 20 in rotation around its axis of rotation XX, in other words the centering and rotation of the fan shaft 25. The fan shaft 25 can advantageously comprise three devices spaced from each other in the longitudinal direction.

[0047] Centering and guiding device

[0048] Each of such devices comprises a bearing 3, such as for example a plain bearing 3 or a rolling bearing, and a support 4 of the bearing 3, positioned radially around the bearing 3 in order to fix the bearing 3 to a part fixed relative to the engine casing 21.

[0049] Preferably, the bearing 3 is a rolling bearing. The bearing 31 comprises an inner ring 31, an outer ring 32 and rolling bodies 33. The outer ring 32 is positioned radially outside the inner ring 31 and the rolling bodies 33 are positioned in the bearing 31 between the inner ring 31 and the outer ring 32. The rolling bodies 33 may be balls, cylinders, truncated cones, or any other element allowing the relative rotational movement of the inner ring 31 and the outer ring 32.

[0050] The outer ring 32 is fixed to the support 4 of the bearing 3, in other words to the engine casing 21. The inner ring 31 is mounted on the fan shaft 25.

[0051] In order to allow radial displacement of the fan shaft 25, the device preferably comprises an annular connection 34. The connection 34 allows radial displacement of the fan shaft 25 during normal operation of the engine 2 but also in the event of an exceptional problem such as the loss of one or more fan blades 20 causing an imbalance.

[0052] Soft cage

[0053] The annular connection 34, or flexible cage or so-called squirrel cage, is configured to connect the outer ring 32 to the support 4. Advantageously, the outer ring 32 and the annular connection 34 form a single piece, as illustrated as an example in Figure 4.

[0054] The annular fitting 34 is monolithic. The annular fitting 34 comprises a first flange 35 and a second flange 36, as illustrated in FIG. 5. The first flange 35 and the second flange 36 are annular and concentric.

[0055] The first flange 35 comprises several arms 37 arranged side by side on the circumference of the fitting 34. Each arm 37 of the first flange 35 extends from a first end 371 to a second end 372. The first end 371 of the arm 37 is connected to the outer ring 32 and the second end 372 is connected to the second flange 36 of the fitting

[0056] 34. In other words, the first end 371 of each arm 37 has a first radius, relative to the axis of rotation XX of the fan shaft 25, and the second end 372 has a second radius, greater than the first radius.

[0057] Each arm 37 comprises end to end, from the first end 371 to the second end 372, a first section 373, a second section 374 and a third section 375. The first section 373 extends axially from the first end 371, i.e. from the outer ring 32. The second section 374 extends radially and outwards from the first section 373. The third section 375 extends axially from the second section 374 towards the second end 372, i.e. towards the second flange 36 of the connector 34. Each arm 37 of the first flange 35 is thus arranged in an axial plane. Advantageously, the first flange 35 thus has a U shape in an axial section plane. The arms 37 thus allow radial movements. The first flange 35 therefore makes it possible to obtain damping, by radial flexibility, while achieving the centering and guiding of the fan shaft 25.

[0058] The second flange 36 is disposed around and radially outside the first flange

[0059] 35. The second flange 36 comprises holes 361 distributed over the entire circumference of the second flange 36. The holes 361 of the second flange 36 allow the second flange 36, and therefore the annular connector 34, to be fixed to the support 4. The second flange 36 may, for example, comprise as many holes 361 as the first flange 35 comprises arms 37. Advantageously, each hole 361 may be positioned at the axial level of each arm 37 of the first flange 35.

[0060] It is possible that the outer ring 32 is driven in rotation relative to the support 4. This unwanted phenomenon may be due to excessive friction between the rolling bodies 33 and the inner ring 31 and the outer ring 32, or to ovalization of the bearing 3 or creeping. The rotation of the outer ring 32 around the axis of rotation X-X of the fan shaft 25 causes a tangential displacement of the outer ring, and therefore of the annular connection 34, relative to the support 4. However, each first arm 37 of the first flange 35 is connected to the outer ring 32 while each third arm 37 of the first flange 35 is connected to the second flange 36 which is fixed to the support 4. A rotation of the outer ring 32 around the axis of rotation XX of the fan shaft 25 therefore causes a tangential displacement between the first arm 37 and the third and more particularly between the first end 371 and the second end 372 of the arm 37.Such a movement can cause deformation or even rupture of one or more arms 37.

[0061] In order to avoid tangential displacement, the device may preferably comprise a wedge 5, as illustrated in figure 4.

[0062] Mechanical wedge

[0063] The shim 5, called the mechanical shim, is configured to allow damping of the connection 34 and therefore a certain radial displacement but also to control the tangential displacement of the first end 371 relative to the second end 372 of each arm 37 of the first flange 35 of the connection 34.

[0064] The device advantageously comprises several shims 5. The device may comprise as many shims 5 as the absolute value of the number of arms 37 divided by two. The device may for example comprise between 3 and 10 shims 5 and advantageously 6 shims 5. The support 4, the bearing 3 and the shim(s) 5 form an assembly for the centering and rotation of the fan shaft 25.

[0065] Each shim 5 is positioned in the connection 34 and preferably at regular intervals around the connection 34. Each shim 5 is positioned in the connection 34 between a first arm 37a and a second arm 37b, the second arm 37b being adjacent to the first arm 37a. The shim 5 is positioned between the first arm 37 and the second arm 37 at the first end 371 and the second end 372 of each of the first arm 37 and the second arm 37. The shim 5 extends radially from the third section 375 to the first section 373 of each of the first arm 37 and the second arm 37. In other words, the shim 5 once positioned in the fitting 34, the fitting 34 being in an unconstrained configuration, it extends from a radius equal to the radius of the first section 373 to a radius equal to the radius of the third section 375.

[0066] Advantageously, the shim 5 comprises lugs 51 for fixing to the connection 34, as illustrated in FIG. 6. The lugs 51 comprise holes adapted to the holes 361 of the second flange 36 and making it possible to fix the shim 5 to the support 4, and therefore to the engine casing 21. The shim 5 may comprise two lugs 51 in order to prevent any movement of the shim 5 relative to the support 4.

[0067] The mechanical shim 5 can allow a relative tangential displacement between the first end 371 and the second end 372 of each of the first arm 37 and the second arm 37 for example up to 3 mm and more preferably up to 1 mm and prevent any tangential displacement greater than 3 mm more preferably greater than 1 mm. The shim 5 therefore comprises: between the first end 371 of each of the first arm 37 and the second arm 37 a tangential width equal to a distance between the first end 371 of the first arm 37 and the first end 371 of the second arm 37 minus 3 mm, and

[0068] - between the second end 372 of each of the first arm 37 and the second arm 37 a tangential width equal to a distance between the second end 372 of the first arm 37 and the second end 372 of the second arm 37 minus 3mm.

[0069] Furthermore, the shim 5 is a part added to the connection 34 and may be made of a material different from or similar to the material making up the connection 34.

Claims

CLAIMS 1. Turbomachine assembly, comprising: a rolling bearing (3) comprising an inner ring (31) and an outer ring (32), an annular connection (34) configured to connect (34) the outer ring (32) to a support (4), the annular connection (34) comprising a first flange (35) and a second flange (36), arranged around and radially outside the first flange (35) and comprising bores (361) for attachment to the support (4), the first flange (35) being formed of several arms (37) arranged side by side on the circumference of the connection (34), each arm (37) of the first flange (35) comprising a first end (371) and a second end (372), and end to end from the first end (371) to the second end (372), a first section (373) extending axially from the outer ring (32), a second section (374) extending radially from the first section (373),then a third section (375) extending axially from the second section (374) towards the second flange (36), and a mechanical wedge (5) positioned between a first of the arms (37) and a second of the adjacent arms (37) and extending radially from the first end (371) to the second end of the arms (37), opposite the second section (374) with respect to the first section (373) and the third section (375), the mechanical wedge (5) being capable of preventing a relative tangential displacement between the first end (371) and the second end (372) of the arms (37) greater than 3 mm by contact between the first of the arms (37) and the second of the arms (37)., 2. Assembly according to claim 1, in which the mechanical wedge (5) comprises lugs (51) for fixing to the connector (34), the lugs (51) being adapted to the holes (361) of the second flange (36).

3. Assembly according to any one of claims 1 and 2, in which the mechanical wedge (5) is capable of allowing a relative tangential displacement between the first end (371) and the second end (372) of the arms (37) of up to 3 mm.

4. Assembly according to any one of claims 1 to 3, comprising a plurality of mechanical shims (5) positioned at regular intervals around the annular connection (34).

5. Device for centering and guiding in rotation around an axis, a rotating part of a turbomachine, the device comprising: a turbomachine assembly according to any one of claims 1 to 4, and a support (4) for a bearing (3) positioned radially outside the outer ring (32).

6. Device according to claim 5, in which the annular assembly is suitable for being fixed to the support (4) by screw elements and each mechanical wedge (5) is fixed to the annular assembly by one or more of the screw elements for fixing the annular assembly to the support (4).

7. Aircraft engine (2) comprising: - a fan shaft (25) rotating around an axis (XX), - a device according to any one of claims 5 and 6, suitable for centering and guiding in rotation the fan shaft (25) around the axis (XX).

8. An aircraft (100) comprising an airframe and an engine (2) according to claim 7, wherein the engine (2) is attached to the airframe.

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