Device for centring and guiding the rotation of a turbine engine shaft with optimised lubrication of rolling elements using lubricant discharged from an sfd

Abstract

The invention relates to a device (30) for centring and guiding the rotation of a turbine engine shaft, the device comprising a rolling bearing (32), a bearing support (34) and an annular damping cavity (52) formed between an inner annular surface (50) of the bearing support (34) and an outer annular surface (48) of an outer ring (38) of the bearing. A discharge duct (70) formed in the outer ring (38) connects a fluid inlet (72) that opens into the annular damping cavity (52) to a fluid outlet (74) that opens through an inner annular surface (44) of the outer ring (38) and is inclined towards an annular row of rolling elements (40) of the bearing in order to lubricate these elements using liquid lubricant discharged from the annular damping cavity (52). A location at which a supply duct (60) opens through the inner annular surface (50) of the bearing support (34) is axially offset relative to the fluid inlet (72).

Description

[0001] Description

[0002] Title: Device for centering and guiding the rotation of a turbomachine shaft with optimized lubrication of rolling elements by lubricant discharged from a

[0003] SFD

[0004] Technical field

[0005] The present invention relates to the field of turbomachines, in particular for aircraft, and more particularly concerns a device for centering and guiding the rotation of a turbomachine rotor shaft, comprising a bearing with oil film compression damping, also called an "SFD" bearing (from the English "Squeeze Film Damping").

[0006] State of the prior art

[0007] A device for centering and guiding the rotation of a turbomachine rotor shaft of the SFD bearing type is a known means for damping vibrations of the shaft, as explained for example in the applicant's document EP1650449B1.

[0008] With reference to the attached figure 1A, which shows such a device schematically, the reference 210 designates a rotor shaft of a turbomachine intended for the propulsion of an aircraft, such as an aircraft turbojet or turboprop. This rotor shaft 210 is centered and guided in rotation in a rolling bearing 212. The latter comprises an outer ring 214 carried by an elastically deformable perforated structure 216, commonly called a “squirrel cage” or “flexible cage”, itself carried by a stator structure of the turbomachine, so as to offer a certain degree of radial movement, or orbiting, to the outer ring, under the effect of vibrations of the shaft, for example following an unbalance.

[0009] The outer ring 214 is mounted in a cylindrical housing 218 defined by a bearing support 220 to form around the outer ring 214 an oil film compression damper (SFD). For this purpose, an annular damping cavity 222 is delimited around the outer ring 214 by the cylindrical surface 221 of the bearing support 220 defining the housing 218, and is axially closed by annular seals 224 mounted in annular grooves 226 formed in the external cylindrical surface of the ring 214. In the field of aircraft turbojets or turboprops, particularly in regions exposed to the highest temperatures, the annular seals 224 are generally elastically deformable split rings, made of a metal resistant to high temperatures.Seals of this type are sometimes called "metal segments", or "piston rings" in English terminology, due to the common use of seals of this type to ensure the sealing of pistons.

[0010] The annular cavity 222 is filled with a lubricant, typically oil, supplied by one or more inlet orifice(s) 228 formed by a radial bore in the casing 220 and opening into an annular groove 230 formed in the cylindrical surface 221 and opening into the annular cavity 222.

[0011] Thus, any orbiting of the outer ring would lead to a crushing of the lubricant film defined by the aforementioned cavity, such crushing being the cause of damping.

[0012] Such damping capacity makes it possible to reduce design loads, and therefore to lighten structures, resulting in an overall reduction in mass.

[0013] To prevent excessive heating of the lubricant within such a cavity, the lubricant is continuously supplied to and removed from the cavity, so as to allow continuous circulation of the lubricant. The lubricant is generally removed via one or more leakage sections provided at the level of the annular sealing rings axially delimiting the cavity. These leakage sections are generally defined by the slots in the segments constituting the sealing rings and / or by notches formed in these segments.

[0014] Furthermore, Figure 1 of the applicant's document EP3850233A1 illustrates a bearing of the type described above within a rear part of a turbojet engine, where this bearing establishes a force path between the downstream end of a low-pressure rotor shaft and an exhaust casing. In this example, the lubrication of the bearing is ensured by lubricant supplied from a region radially external to the bearing, by one or more pipes running for example through one or more arms of the exhaust casing and ending in one or more cannulas opening into an enclosure defined downstream of the bearing and adjacent to the latter.

[0015] Figure 1 of document EP3850233A1 illustrates the fact that the space available in the immediate environment of a bearing can be considerably restricted. This limits in particular the possibilities of lubricating the bearing from both upstream and downstream, in cases where, as in this figure 1, the lubricant supply must be carried out from a region radially external to the bearing (and not from a pipe running within the shaft). However, lubrication of the two opposite sides of such a bearing is often desirable to improve the mechanical strength of the bearing and reduce the thermal gradients within it, and thus improve the service life of the bearing.

[0016] Statement of the invention

[0017] The invention relates to a device for centering and guiding in rotation a rotor shaft of a turbomachine of the SFD bearing type, which is suitable for situations in which little space is available for bearing lubrication means which must operate by means of lubricant supplied from a region radially external to the bearing.

[0018] For this purpose, it offers a device for centering and guiding the rotation of a turbomachine shaft, comprising:

[0019] - a rolling bearing comprising an inner ring, an outer ring defining an axis of the rolling bearing and having an outer annular surface, and an annular row of rolling elements interposed between an outer annular surface of the inner ring and an inner annular surface of the outer ring;

[0020] - a bearing support having an inner annular surface surrounding the outer annular surface of the outer ring;

[0021] - an annular damping cavity, formed between the inner annular surface of the bearing support and the outer annular surface of the outer ring and defined axially between two annular sealing gaskets each formed of a split overlapping metal ring;

[0022] - a supply pipe provided in the bearing support and opening through the internal annular surface of the latter into the annular damping cavity to supply the latter with lubricating liquid to form a damping film therein;

[0023] - a discharge pipe provided in the outer ring and connecting a fluid inlet, which opens through the outer annular surface of the outer ring into the annular damping cavity, to a fluid outlet, in which said fluid outlet:

[0024] - opens through the inner annular surface of the outer ring at a location axially offset from the annular row of rolling elements and at which the inner annular surface of the outer ring faces the outer annular surface of the inner ring, and

[0025] - is inclined towards the annular row of rolling elements, to lubricate the latter by means of lubricating liquid discharged from the annular damping cavity.

[0026] The configuration of the device, in particular of the fluid outlet of the outer ring of the bearing, allows lubrication of one side of the rolling elements by means of the lubricant coming from the damping cavity, which makes it possible to avoid the use of means dedicated to this lubrication such as one or more cannulas, while being compatible with a supply of lubricant from a radially external region. The device according to the invention is thus particularly advantageous in cases where little space is available for the arrangement of dedicated lubrication means, as well as in cases where lubrication of both sides of the bearing is desirable.

[0027] In addition, a location at which the supply pipe opens through the inner annular surface of the bearing support is axially offset relative to a location at which the discharge pipe opens through the outer annular surface of the outer ring, i.e. a location of the aforementioned fluid inlet. Such an arrangement makes it possible to optimize the formation of the damping film by the lubricating liquid. Of course, this is all the more true since the aforementioned axial offset is significant with respect to the axial extent of the annular damping cavity.

[0028] In preferred embodiments, the location at which the supply line opens through the inner annular surface of the bearing support and the location at which the discharge line opens through the outer annular surface of the outer ring are arranged on either side of a median axial plane of the annular damping cavity.

[0029] In preferred embodiments, the outer annular surface of the inner ring of the rolling bearing has an annular portion flared towards the annular row of rolling elements and axially offset relative to the latter, to constitute an acceleration ramp for lubricating liquid from the fluid outlet.

[0030] In preferred embodiments, the supply duct comprises an annular distribution plenum, and an annular row of distribution passages opening, at one end, into the annular distribution plenum, and at an opposite end, through the inner annular surface of the bearing support, into the annular damping cavity.

[0031] In preferred embodiments, the bearing support comprises two respective concentric annular parts rigidly secured to each other and having two respective contact surfaces in contact with each other, and the annular distribution plenum is formed by an annular groove formed in one of said contact surfaces and is delimited by the other of said contact surfaces.

[0032] In preferred embodiments, the supply pipe opens into an annular distribution groove formed in the inner annular surface of the bearing support and opening annularly into the annular damping cavity.

[0033] In preferred embodiments, the discharge pipe comprises an annular discharge plenum, at least one supply passage connected to the annular discharge plenum at one end of said supply passage and forming said fluid inlet at an opposite end of said supply passage, and at least one ejection passage connected to the annular discharge plenum at one end of said ejection passage, and opening, at an opposite end of said ejection passage, through the inner annular surface of the outer ring, along an ejection axis inclined towards the annular row of rolling elements, so as to form said fluid outlet.

[0034] In preferred embodiments, said annular exhaust plenum is a first annular exhaust plenum, said at least one ejection passage is a first ejection passage, said ejection axis is a first ejection axis, and said fluid outlet is a first fluid outlet.In addition, the discharge pipe comprises a second annular discharge plenum connected to the annular damping cavity, and at least one second ejection passage connected to the second annular discharge plenum at one end of said second ejection passage and opening, at an opposite end of said second ejection passage, through the inner annular surface of the outer ring at a location situated axially on a side opposite the first fluid outlet relative to the annular row of rolling elements, along a second ejection axis inclined towards the annular row of rolling elements, so as to form a second fluid outlet capable of lubricating the rolling elements by means of fluid discharged from the annular damping cavity.

[0035] In preferred embodiments, the exhaust duct includes at least one connecting passage connecting the first annular exhaust plenum to the second annular exhaust plenum, whereby the connection of the second annular exhaust plenum to the annular damping cavity is provided via the supply passage, the first annular exhaust plenum, and the connecting passage.

[0036] In preferred embodiments, said fluid inlet is a first fluid inlet, and said supply passage is a first supply passage. In addition, the discharge line comprises at least one second supply passage connected to the second annular discharge plenum at one end of said second supply passage and forming, at an opposite end of said second supply passage, a second fluid inlet which opens through the outer annular surface of the outer ring into the annular damping cavity at a location axially offset from the first fluid inlet, whereby the connection of the second annular discharge plenum to the annular damping cavity is ensured via the second supply passage.

[0037] In preferred embodiments, the location at which the supply line opens into the annular damping cavity is located axially between said first and second fluid inlets.

[0038] In preferred embodiments, the device comprises a lubrication cannula configured to spray lubricating liquid onto a side of the annular row of rolling elements opposite said fluid outlet.

[0039] In preferred embodiments, the fluid outlet and / or, where appropriate, the second fluid outlet, is tangentially inclined to impart a rotating motion to the lubricating liquid.

[0040] In preferred embodiments, said inner annular surface of the outer ring has a cylindrical shape of revolution and extends axially beyond the annular row of rolling elements on either side of the latter.

[0041] Brief description of the drawings

[0042] The invention will be better understood, and other details, advantages and characteristics thereof will appear on reading the following description given by way of non-limiting example and with reference to the appended drawings in which:

[0043] [Fig IA], already described, is a schematic view in axial section and in perspective of a device for centering and guiding in rotation a shaft in a turbomachine, of known type;

[0044] [Fig IB] is a schematic axial sectional view of an aircraft turbomachine; [Fig IC] is a larger-scale schematic axial sectional view of a rear part of a turbomachine of known type;

[0045] [Fig 2A] is a schematic axial sectional view of a device for centering and guiding the rotation of a shaft in a turbomachine such as that of FIG. 1B, according to a preferred embodiment of the invention;

[0046] [Fig 2B] is a partial schematic perspective view of an annular sealing gasket belonging to the device of Figure 2A;

[0047] [Fig 2C] is a view similar to Fig. 2A, illustrating the device in a carriage configuration;

[0048] [Fig. 3] is a view similar to Fig. 2A, illustrating a variation of the device;

[0049] [Fig. 4] is a view similar to Fig. 2A, illustrating another variation of the device;

[0050] [Fig. 5] is a view similar to Fig. 2A, illustrating another variation of the device;

[0051] [Fig. 6] is a view similar to Fig. 2A, illustrating another variation of the device;

[0052] [Fig. 7] is a view similar to Fig. 2A, illustrating another variation of the device;

[0053] [Fig. 8] is a view similar to Fig. 2A, illustrating another variation of the device.

[0054] Throughout the following description and the accompanying drawings, identical reference numerals may designate similar or analogous elements.

[0055] Detailed disclosure of preferred embodiments

[0056] Figure 1B illustrates a turbomachine 10, for example a twin-spool, dual-flow turbojet engine for aircraft, generally comprising a fan 12 intended for the suction of an air flow F1 dividing downstream of the fan into a primary flow F2 circulating in a primary flow channel, hereinafter referred to as the primary flow path PV, and a secondary flow F3 circulating in a secondary flow channel, hereinafter referred to as the secondary flow path SV, arranged around the primary flow path PV.

[0057] By way of illustration, the turbomachine generally comprises a low-pressure compressor 14, a high-pressure compressor 16, a combustion chamber 18, a high-pressure turbine 20 and a low-pressure turbine 22 which jointly define the primary stream PV. The respective rotors of the high-pressure compressor and the high-pressure turbine are connected by a shaft 24 called the “high-pressure shaft”, while the respective rotors of the low-pressure compressor and the low-pressure turbine are connected by a shaft 26 called the “low-pressure shaft”, in a well-known manner. These rotors are rotatably mounted about an axis 28 of the turbomachine. For this purpose, devices 30A, 30B ensure the centering and rotational guidance of the high-pressure shaft 24, while devices 30C-30E ensure the centering and rotational guidance of the low-pressure shaft 26.These devices 30A-30E, which each comprise a rolling bearing, establish force paths between the shafts 24, 26, on the one hand, and the casings of the turbomachine, on the other hand, in a well-known manner.

[0058] Throughout this description, the axial direction X is the direction of the axis 28. We further consider a cylindrical coordinate system centered on the axis 28, in which a radial direction R is at all points orthogonal to the axis 28 and passes through the latter, while an ortho-radial or circumferential direction C is at all points orthogonal to the radial direction R and to the axis 28. A transverse plane is a plane orthogonal to the axis 28. The terms “internal” and “external” refer respectively to a relative proximity, and a relative distance, of an element with respect to the axis 28. Finally, the “upstream” and “downstream” directions are defined with reference to the general direction FD of the gas flow in the primary PV and secondary SV veins of the turbomachine, in the axial direction X.

[0059] Figure IC illustrates on a larger scale a rear part of a turbomachine such as the turbomachine of Figure IB, and in particular allows a view to be seen of a rotor of the low-pressure turbine 22, formed of bladed discs 22A arranged alternately with distributors 22B and connected to the low-pressure shaft 26, as well as an exhaust casing 29 arranged downstream of the turbine 22.

[0060] Figure IC further shows a device 30 for centering and guiding the rotation of the low pressure shaft 26, corresponding for example to the device 30E of Figure 1B.

[0061] This device 30 generally comprises a rolling bearing 32, and a bearing support 34 rigidly connected to the exhaust casing 29. The rolling bearing 32 comprises an inner ring 36, an outer ring 38, and an annular row of rolling elements 40, for example rollers, interposed between the inner ring 36 and the outer ring 38.

[0062] The outer ring 38 is for example carried by an elastically deformable openwork structure 31 or “squirrel cage” similar to the structure 216 of FIG. 1A, itself fixed to a flange 33 secured to the bearing support 34 and, more generally, secured to the exhaust casing 29.

[0063] An annular cavity called a damping cavity 52, intended to receive lubricating liquid to form a fluid film compression damper (SFD), is formed between an internal annular surface of the bearing support 34 and an external annular surface of the outer ring 38. In this cavity 52 opens a lubricant pipe 35 to which a lubricant supply pipe 37 is connected.

[0064] Furthermore, the lubrication of the bearing 32 is ensured by a lubrication cannula 39 designed to bring lubricant from a radially external, and downstream, region relative to the bearing 32, and to project this lubricant upstream towards a downstream face of the bearing 32. This cannula extends for example through one of the openings defined by the squirrel cage 31.

[0065] Figure IC illustrates an example of a configuration in which the space available for means of lubricating the bearing, in particular the upstream face of the latter, is particularly limited. In the example illustrated, such a limitation comes from the fact that a JRS annular seal, of the “segmented radial” type as shown in Figure 1 of document EP2870323A1, is arranged around the device 30. Such positioning of the JRS seal allows the contact track thereof to be lubricated without the risk of direct projection of lubricant at the interface between the seal and the contact track.

[0066] The invention aims to enable optimal lubrication of a bearing in configurations offering little space, such as for example the configuration visible in figure IC.

[0067] The invention is, in general, applicable to any type of turbomachine, whether single-flow or multi-flow, single-body or multi-body. The invention relates more specifically to a device for centering and guiding the rotation of a shaft within such a turbomachine, of the SFD bearing type.

[0068] Figure 2A illustrates such a device 30. The latter comprises in particular a rolling bearing 32 and a bearing support 34.

[0069] The rolling bearing 32 comprises an inner ring 36, an outer ring 38, and an annular row of rolling elements 40 interposed between an outer annular surface 42 of the inner ring 36 and an inner annular surface 44 of the outer ring 38. The rolling elements 40 are typically associated with an annular cage, in a well-known manner.

[0070] The outer ring 38 is typically intended to be carried by an elastically deformable openwork structure such as the structure 31 of FIG. 1C.

[0071] In the examples described below, the outer ring 38 is formed of an inner annular body 38A, which defines the inner annular surface 44, and an annular hoop 38B mounted around the inner annular body 38A by hooping. This feature makes it easier to manufacture the outer ring 38. The latter can nevertheless be produced in one piece, as a variant, for example by means of an additive manufacturing technique.

[0072] In cases where the rolling elements 40 are rollers, the internal annular surface 44 of the outer ring 38 has a cylindrical shape of revolution along an axis defined as axis 46 of the bearing 32 and which coincides for example with the axis 28 of the turbomachine.

[0073] Furthermore, the outer ring 38 has an external annular surface 48. The latter is, in this case, defined by the annular hoop 38B. In addition, the bearing support 34 has an internal annular surface 50 surrounding the external annular surface 48 of the outer ring 38. The two surfaces 48 and 50 are centered along the axis 46 of the bearing.

[0074] An annular cavity called a damping cavity 52, intended to receive lubricating liquid to form a damping film or “squeeze film”, is formed between the internal annular surface 50 of the bearing support and the external annular surface 48 of the outer ring and is defined axially between two annular sealing joints 54A, 54B mounted in corresponding annular grooves formed in the surface 48 so as to each be in contact over 360 degrees with the surface 50.

[0075] These seals 54A, 54B are configured to axially close the annular damping cavity 52 in a sealed or substantially sealed manner, unlike seals commonly used in known squeeze film bearings, configured to provide at least one leakage section as explained above.

[0076] For this purpose, the seals 54A, 54B are for example overlapping split metal rings. As illustrated in FIG. 2B, such a seal, without notches, has two ends defined on either side of the slot, one of which 56A forms a tenon and the other of which 56B has a cutout of a shape substantially complementary to the tenon and formed on one side of the seal opposite the annular damping cavity 52, to receive the tenon with a small clearance in the circumferential direction, typically of the order of a few tenths of a millimeter to a few millimeters, so that such a seal does not have any fluid passage section opening directly into the annular damping cavity 52 and thus makes it possible to maximize the sealing with respect to the lubricant present in the annular damping cavity 52.

[0077] Furthermore, the device 30 comprises a supply pipe 60 arranged in the bearing support 34 and opening, through the internal annular surface 50 of the latter, into the annular damping cavity 52, to supply the latter with lubricating liquid to form the aforementioned damping film there.

[0078] By "pipeline" is generally understood, in this description, any channel or network of channels adapted to the circulation of a liquid.

[0079] The supply pipe 60 comprises one or more intake passage(s) 62 for the lubricant, the latter being able to come from any circuit or any source available for this purpose in the turbomachine.

[0080] In the example illustrated in FIG. 2A, the supply pipe 60 further comprises an annular distribution plenum 64, and an annular row of distribution passages 66 opening, at one end, into the annular distribution plenum 64, and at an opposite end, through the internal annular surface 50 of the bearing support 34, into the annular damping cavity 52. ​​The plenum 64 makes it possible to promote the homogeneity of the temperature of the lubricant before the latter reaches the annular damping cavity 52.

[0081] To easily form the annular distribution plenum 64, the bearing support 34 (or at least the annular portion of the latter defining the internal annular surface 50) can be produced using an additive manufacturing technique.

[0082] In addition, the external annular surface 48 of the outer ring 38 of the bearing advantageously comprises an annular distribution groove 68 opposite which the distribution passages 66 open, to promote the homogenization of the lubricant upon its arrival in the annular damping cavity 52.

[0083] Furthermore, the device 30 comprises an evacuation pipe 70 arranged in the outer ring 38 and having, at one end, a fluid inlet 72, and at an opposite end, a fluid outlet 74.

[0084] The fluid inlet 72 opens, through the external annular surface 48 of the outer ring, into the annular damping cavity 52.

[0085] The fluid outlet 74 opens, through the inner annular surface 44 of the outer ring, at a location axially offset relative to the annular row of rolling elements 40 and in which the inner annular surface 44 of the outer ring 38 faces (directly) the outer annular surface 42 of the inner ring 36. It should be understood by this that these two surfaces 42 and 44 are then separated from each other, on each side of the annular row of rolling elements 40, by an annular space 75A, 75B into which the fluid outlet 74 opens and which extends axially to the annular row of rolling elements 40. In addition, the fluid outlet 74 is inclined towards the rolling elements 40, to lubricate the latter by means of lubricating liquid discharged from the annular damping cavity 52.In operation, this liquid is at a pressure substantially equal to the supply pressure of the annular damping cavity 52 (apart from pressure losses), due to the perfect or almost perfect sealing ensured by the overlapping seals 54A, 54B. This pressure is typically from a few bars to a few tens of bars, depending on the desired damping level. The fluid outlet 74 may be formed by the end of an ejection passage 76 formed in the outer ring 38 or by the respective ends of a plurality of such ejection passages 76 distributed around the axis 46. The ejection passage 76, or each ejection passage 76, defines a respective ejection axis 78 inclined towards the rolling elements 40 and thus defining the aforementioned inclination of the fluid outlet 74.

[0086] The fluid outlet 74 is calibrated, that is to say it has a fluid passage section determined as a function of the desired flow rate and pressure for the lubricant ejected by this fluid outlet 74 and to ensure an appropriate liquid pressure within the annular damping cavity 52 as a function of the desired damping level. The fluid passage section defined by the ejection passage 76, or by each ejection passage 76, is advantageously sized to diffuse a jet of lubricant in the manner of a nozzle.

[0087] Thus, the invention allows efficient lubrication of the rolling elements 40 by means of lubricant discharged from the annular damping cavity 52, directly from the inner annular surface 44 of the outer ring 38. This lubrication, implemented from lubricant supplied from a region radially external to the bearing 32 (unlike certain known configurations in which the lubricant is supplied to the bearing through the shaft, from a radially internal region), does not require a cannula or other bulky member and thus has the advantage of being able to be implemented even in an environment with little available space such as that illustrated in FIG. 1C.

[0088] In the illustrated example, the invention is implemented in conjunction with a lubrication cannula 39 such as that visible in FIG. 1C, the latter ensuring lubrication of the downstream side of the bearing 32 while the fluid outlet 74 ensures lubrication of the upstream side of the bearing 32. This example thus illustrates another advantage of the invention, namely the possibility of lubricating both sides of a bearing 32 despite the limited space available for this purpose. Such lubrication of both sides makes it possible to improve the mechanical strength of the bearing and to reduce thermal gradients within the bearing, and thus to improve the service life of the bearing.Furthermore, the inner annular surface 44 of the outer ring 38 preferably extends not only around the annular row of rolling elements 40 but also beyond and on either side of it in the axial direction, so as to allow a certain axial movement or carriage of the assembly constituted by the annular row of rolling elements 40 and the inner ring 36. Such axial movement occurs in particular due to axial thermal expansions, when the device 30 is arranged in a region where particularly high temperatures prevail, for example within a turbine.

[0089] The fluid outlet 74 formed in the inner annular surface 44 in fact makes it possible to lubricate the rolling elements 40 without requiring a component likely to obstruct axial movement of the annular row of rolling elements 40 and the inner ring 36. FIG. 2A thus illustrates the device 30 in a configuration of maximum carriage in the upstream direction, while FIG. 2C illustrates the device 30 in a configuration of maximum carriage in the downstream direction. Thus, in FIG. 2C, the annular row of rolling elements 40 and the inner ring 36 have moved axially (to the right) relative to FIG. 2A. A nominal configuration of the device 30 is defined so that the annular row of rolling elements 40 and the inner ring 36 are in a middle position relative to the extreme positions of FIGS. 2A and 2C.

[0090] The outer annular surface 42 of the inner ring 36 of the bearing preferably has an annular portion 79 flared in the direction of the annular row of rolling elements 40 and axially offset relative to the latter, on the same side as the fluid outlet 74, to constitute an acceleration ramp for lubricating liquid coming from the fluid outlet 74. Due to the rotation of the inner ring 36 and the resulting centrifugal force, to which the lubricant is subjected in contact with the aforementioned annular portion 79 of the surface 42, the lubricant which would reach this annular portion 79 would in fact be accelerated in the direction of the rolling elements 40.Such a flared annular portion 79 is all the more advantageous when the device is in the rolling configuration, which results in a relative axial distance between the fluid outlet 74 and the annular row of rolling elements 40, so that the fluid outlet 74 is located axially at the level of the annular portion 79.

[0091] The ejection axis 78 is preferably included in an angle defined between two half-lines L1 and L2 each having as a vertex a center of the entrance of the ejection passage 76, and such that: the first half-line L1 passes through a point located at the base of the flared annular portion 79 of the external annular surface 42 of the inner ring 36, when the device is in the maximum rolling configuration in the downstream direction (figure 2C); and the second half-line L2 passes through a radially external end of the annular row of rolling elements 40, when the device is in the maximum rolling configuration in the upstream direction (figure 2A). Thus, whatever the axial position of the annular row of rolling elements 40 between the two aforementioned extreme rolling positions, these elements 40 receive lubricant, either directly or after trickle-centrifugation on the flared annular portion 79.

[0092] In addition, the fluid outlet 74 is advantageously inclined tangentially to impart a rotating movement to the lubricating liquid. It should be understood, in this case, that the ejection axis 78 of the discharge passage or of each discharge passage is not included in any plane comprising the axis 46 of the bearing, and that such an axis 78 therefore extends in a direction comprising not only a component in the axial direction X but also a component in the circumferential direction C.

[0093] Furthermore, the location at which the supply pipe 60 opens through the inner annular surface 50 of the bearing support 34 is axially offset relative to the location at which the discharge pipe 70 opens through the outer annular surface 48 of the outer ring 38. These two locations are preferably arranged on either side of a median axial plane M of the cavity 52 and are, ideally, located respectively near the two opposite axial ends of the cavity 52 defined by the seals 54A, 54B. Thus, the path to be followed by the liquid within the cavity 52 to reach the discharge pipe 70 can be maximized, which tends to promote the homogeneity of the liquid pressure within the cavity 52 and thus makes it possible to optimize the damping capabilities by the SFD.In the example illustrated in Figure 2A, the discharge pipe 70 comprises: an annular discharge plenum 80; at least one supply passage 82 connected to the annular discharge plenum 80, at one end, and forming the aforementioned fluid inlet 72, at an opposite end; and the ejection passage 76 or each ejection passage 76, connected to the annular discharge plenum 80, at one end, and forming the aforementioned fluid outlet 74, at an opposite end. The annular discharge plenum 80 makes it possible to promote the homogeneity of the temperature of the lubricant before the latter is ejected towards the rolling elements through the ejection passage 76 or each ejection passage 76.

[0094] The annular discharge plenum 80 is for example jointly defined by an annular groove formed in an outer annular surface 84A of the inner annular body 38A and by an inner annular surface 84B of the annular hoop 38B. This plenum can thus be easily produced by machining the outer annular surface 84A of the inner annular body 38A before assembling the latter with the annular hoop 38B.

[0095] The rolling elements 40 of the device 30 visible in Figures 2A-2C are rollers.

[0096] Figure 3 illustrates a variant in which the rolling elements 40 are balls.

[0097] In a variant illustrated in Figure 4, the supply pipe 60 opens into an annular distribution groove 90 formed in the inner annular surface 50 of the bearing support 34 and opening annularly into the annular damping cavity 52. ​​In this case, the annular distribution groove 90 plays a role similar to that played by the annular distribution plenum 64 and by the annular distribution groove 68 described above. Unlike the plenum 64, the annular distribution groove 90 can be produced by machining the inner annular surface 50 of the bearing support 34, which offers possibilities for easily manufacturing the bearing support 34 by techniques other than additive manufacturing techniques.

[0098] In another variant illustrated in FIG. 5, the annular discharge plenum 80 is jointly defined by an annular groove formed in the inner annular surface 84B of the annular hoop 38B, and by the outer annular surface 84A of the inner annular body 38A. This plenum can thus be easily produced by machining the inner annular surface 84B of the annular hoop 38B before assembling the latter with the inner annular body 38A.

[0099] In another variant illustrated in Figure 6, the bearing support 34 is formed by two respective concentric annular parts 34A, 34B rigidly secured to one another and having two respective contact surfaces 92A, 92B in contact with one another. In addition, the annular distribution plenum 64 is formed by an annular groove formed in one of said contact surfaces and is delimited by the other of said contact surfaces. This feature makes it easier to manufacture the bearing support 34.

[0100] Thus, in the example visible in Figure 6, the bearing support 34 is formed of an external annular body 34A, and an annular hoop 34B mounted inside the external annular body 34A by hooping and defining the internal annular surface 50 of the bearing support 34. In addition, the annular distribution plenum 64 is formed by an annular groove produced by machining in the internal annular surface 92A of the body 34A and is further delimited by the external annular surface 92B of the annular hoop 34B.

[0101] In such cases, the distribution passages 66 are formed through the annular hoop 34B.

[0102] In variants illustrated by Figures 7 and 8, for the sake of clarity, the annular exhaust plenum 80 is called the first annular exhaust plenum, the ejection passage 76 or each ejection passage 76 is called the first ejection passage, the ejection axis 78 or each ejection axis 78 is called the first ejection axis, the fluid outlet 74 is called the first fluid outlet.

[0103] In these variants, the discharge pipe 70 further comprises a second annular discharge plenum 100 connected to the annular damping cavity 52, and at least one second ejection passage 102 connected to the second annular discharge plenum 100 at one end, and opening, at an opposite end, through the inner annular surface 44 of the outer ring 38 at a location situated axially on a side opposite the first fluid outlet 74 relative to the annular row of rolling elements 40, along a second ejection axis 104 inclined towards the annular row of rolling elements 40, so as to form a second fluid outlet 106 capable of lubricating the rolling elements 40 by means of fluid discharged from the annular damping cavity 52.The lubrication of the two opposite sides of the bearing can thus be ensured by means of lubricant from the annular damping cavity 52, without recourse to any lubrication cannula. Such variants are thus particularly suitable in configurations with very little available space.

[0104] In these variants, the outer annular surface 42 of the inner ring 36 of the bearing preferably has an annular portion 108 flared in the direction of the annular row of rolling elements 40 and axially offset relative to the latter, on the same side as the second fluid outlet 106, to constitute an acceleration ramp for lubricating liquid coming from this second fluid outlet 106.

[0105] In the example of Figure 7, the discharge pipe 70 further comprises at least one connecting passage 110 connecting the first annular discharge plenum 80 to the second annular discharge plenum 100, whereby the connection of the second annular discharge plenum 100 to the annular damping cavity 52 is ensured via the supply passage 82 (or each supply passage 82), the first annular discharge plenum 80, and the connecting passage 110 (or each connecting passage 110). In such a case, the trajectory followed by the liquid to pass from the supply pipe 60 to the discharge pipe 70 can be further maximized, as explained above.

[0106] In the example of Figure 8, for clarity, the fluid inlet 72 is referred to as the first fluid inlet, and the supply passage 82 or each supply passage 82 is referred to as the first supply passage. In addition, the discharge pipe 70 comprises at least one second supply passage 112 connected to the second annular discharge plenum 100 at one end, and forming, at an opposite end, a second fluid inlet 114 which opens through the outer annular surface 48 of the outer ring into the annular damping cavity 52 at a location axially offset from the first fluid inlet 72, whereby the connection of the second annular discharge plenum 100 to the annular damping cavity 52 is provided via the second supply passage 112 or each second supply passage 112.

[0107] The location at which the supply pipe 60 opens into the annular damping cavity 52 is advantageously located axially between the first and second fluid inlets 72, 114, for example halfway between the latter, so as to limit the differences in pressure drop experienced by the lubricant before its diffusion through the first fluid outlet 74 and through the second fluid outlet 106, and to maximize here again the trajectory followed by the liquid to pass from the supply pipe 60 to the discharge pipe 70, these two particularities making it possible to guarantee here again optimal damping by the SFD.

Claims

Claims 1. Device (30) for centering and guiding the rotation of a turbomachine shaft, comprising: - a rolling bearing (32) comprising an inner ring (36), an outer ring (38) defining an axis (46) of the rolling bearing and having an outer annular surface (48), and an annular row of rolling elements (40) interposed between an outer annular surface (42) of the inner ring (36) and an inner annular surface (44) of the outer ring (38); - a bearing support (34) having an inner annular surface (50) surrounding the outer annular surface (48) of the outer ring (38); - an annular damping cavity (52), formed between the inner annular surface (50) of the bearing support (34) and the outer annular surface (48) of the outer ring (38) and defined axially between two annular sealing joints (54A, 54B) each formed of a split overlapping metal ring; - a supply pipe (60) provided in the bearing support (34) and opening through the internal annular surface (50) of the latter into the annular damping cavity (52) to supply the latter with lubricating liquid to form a damping film therein; - an evacuation pipe (70) arranged in the outer ring (38) and connecting a fluid inlet (72), which opens through the outer annular surface (48) of the outer ring (38) into the annular damping cavity (52), to a fluid outlet (74), in which said fluid outlet (74): - opens through the inner annular surface (44) of the outer ring (38) at a location axially offset from the annular row of rolling elements (40) and in which the inner annular surface (44) of the outer ring (38) faces the outer annular surface (42) of the inner ring (36), and - is inclined towards the annular row of rolling elements (40), to lubricate the latter by means of lubricating liquid discharged from the annular damping cavity (52); and in which a location at which the supply pipe (60) opens through the inner annular surface (50) of the bearing support (34) is axially offset relative to a location at which the discharge pipe (70) opens through the outer annular surface (48) of the outer ring (38).

2. Device according to claim 1, in which the outer annular surface (42) of the inner ring (36) of the rolling bearing (32) has an annular portion (79) flared in the direction of the annular row of rolling elements (40) and axially offset relative to the latter, to constitute an acceleration ramp for lubricating liquid coming from the fluid outlet (74).

3. Device according to claim 1 or 2, in which the supply pipe (60) comprises an annular distribution plenum (64), and an annular row of distribution passages (66) opening, at one end, into the annular distribution plenum (64), and at an opposite end, through the internal annular surface (50) of the bearing support (34), into the annular damping cavity (52).

4. Device according to claim 3, in which the bearing support (34) comprises two respective concentric annular parts (34A, 34B) rigidly secured to one another and having two respective contact surfaces (92A, 92B) in contact with one another, and in which the annular distribution plenum (64) is formed by an annular groove formed in one of said contact surfaces (92A, 92B) and is delimited by the other of said contact surfaces (92A, 92B).

5. Device according to any one of claims 1 to 4, in which the supply pipe (60) opens into an annular distribution groove. (90) formed in the inner annular surface (50) of the bearing support (34) and opening annularly into the annular damping cavity (52).

6. Device according to any one of claims 1 to 5, wherein the discharge pipe (70) comprises an annular discharge plenum (80), at least one supply passage (82) connected to the annular discharge plenum (80) at one end of said supply passage and forming said fluid inlet (72) at an opposite end of said supply passage, and at least one ejection passage (76) connected to the annular discharge plenum (80) at one end of said ejection passage, and opening, at an opposite end of said ejection passage, through the inner annular surface (44) of the outer ring (38), along an ejection axis (78) inclined towards the annular row of rolling elements (40), so as to form said fluid outlet (74).

7. Device according to claim 6, wherein said annular discharge plenum (80) is a first annular discharge plenum, said at least one ejection passage (76) is a first ejection passage, said ejection axis (78) is a first ejection axis, said fluid outlet (74) is a first fluid outlet, and wherein the discharge pipe (70) comprises a second annular discharge plenum (100) connected to the annular damping cavity (52), and at least one second ejection passage (102) connected to the second annular discharge plenum (100) at one end of said second ejection passage and opening, at an opposite end of said second ejection passage, through the inner annular surface (44) of the outer ring (38) at a location situated axially on a side opposite the first fluid outlet (74) relative to the annular row of rolling elements (40),according to a second ejection axis (104) inclined towards the annular row of rolling elements (40), so as to form a second fluid outlet (106) capable of lubricating the rolling elements (40) by means of fluid discharged from the annular damping cavity (52)., 8. Device according to claim 7, wherein the discharge pipe (70) comprises at least one connecting passage (110) connecting the first annular discharge plenum (80) to the second annular discharge plenum (100), whereby the connection of the second annular discharge plenum (100) to the annular damping cavity (52) is ensured via the supply passage (82), the first annular discharge plenum (80), and the connecting passage (110).

9. Device according to claim 7, wherein said fluid inlet (72) is a first fluid inlet, said supply passage (82) is a first supply passage, and wherein the discharge pipe (70) comprises at least one second supply passage (112) connected to the second annular discharge plenum (100) at one end of said second supply passage and forming, at an opposite end of said second supply passage, a second fluid inlet (114) which opens through the outer annular surface (48) of the outer ring (38) into the annular damping cavity (52) at a location axially offset from the first fluid inlet (72), whereby the connection of the second annular discharge plenum (100) to the annular damping cavity (52) is ensured via the second supply passage (112).

10. Device according to claim 9, wherein the location at which the supply pipe (60) opens into the annular damping cavity (52) is situated axially between said first and second fluid inlets (72, 114).

11. Device according to any one of claims 1 to 6, comprising a lubrication cannula configured to spray lubricating liquid onto a side of the annular row of rolling elements (40) opposite said fluid outlet (74).

12. Device according to any one of claims 1 to 11, in which the fluid outlet (74) and / or, where appropriate, the second fluid outlet (106), is inclined tangentially to impart a rotating movement to the lubricating liquid.

13. Device according to any one of claims 1 to 12, in which said internal annular surface (44) of the outer ring (38) has a cylindrical shape of revolution and extends axially beyond the annular row of rolling elements (40) on either side of the latter.

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