Device for centering and guiding the rotation of a fluid-damped turbomachine shaft and means for safety

Abstract

A device for centering and guiding the rotation of a turbomachine shaft includes locking means (54A, 54B; 130) movable between: a rest position, towards which the locking means are forced by the pressure of a lubricating fluid supplying a film compression damping cavity, and in which the locking means are separated by at least one of a bearing support (34) and an outer ring (38) so as to leave the latter free to move radially relative to each other; and a service position, towards which the locking means are forced by elastic return means (90A, 90B; 156; 180), and in which the locking means are interposed with contact between an external annular surface (48) of the outer ring (38) and an internal annular surface (50) of the bearing support (34) so ​​as to prevent the latter from moving radially relative to each other.Figure for the abbreviation: Figure 3.

Description

Title of the invention: Device for centering and guiding the rotation of a turbomachine shaft with fluid damping and safety means Technical field

[0001] 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 Dumping"). State of the prior art

[0002] A device for centering and guiding in rotation a turbomachine rotor shaft of the SFD bearing type is a known means for enabling the damping of vibrations of the shaft, as explained for example in the document EP1650449B1 of the applicant.

[0003] In such a device, the outer ring of the bearing is generally carried by a stator structure of the turbomachine via an elastically deformable structure in the radial direction, sometimes called a "flexible cage" or "squirrel cage", to provide a certain degree of radial movement, or orbiting, to the outer ring, under the effect of vibrations of the shaft resulting, for example, from an unbalance.

[0004] In addition, a relatively thin annular cavity supplied with lubricating liquid, typically oil, is defined between the outer ring of the bearing and an annular bearing support surrounding the outer ring and also integral with the stator structure.

[0005] Thus, any orbiting of the outer ring leads to a crushing of the lubricant film defined by the aforementioned cavity, such crushing being the cause of damping.

[0006] Such a damping capacity makes it possible to reduce the design loads, and therefore to lighten the structures, resulting in an overall reduction in mass.

[0007] However, in the event of an interruption in the supply of lubricant to the aforementioned cavity, orbiting of the outer ring of the bearing risks damaging the elements constituting the bearing and its support. Statement of the invention

[0008] The invention aims to at least partially remedy the above problem.

[0009] To this end, it proposes a device for centering and guiding the rotation of a turbomachine shaft, comprising: • 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; • a bearing support having an inner annular surface surrounding the outer annular surface of the outer ring; • 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 housed in respective annular grooves each formed in one of the outer annular surface of the outer ring and the inner annular surface of the bearing support; • 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; • an evacuation path defined from the annular damping cavity so as to allow the lubricating liquid to escape from the latter;

[0010] According to the invention, the device further comprises locking means movable between: • a rest position, towards which the locking means are urged by the pressure of the lubricating liquid, and in which the locking means are spaced from at least one of the bearing support and the outer ring so as to leave the latter free to move radially relative to each other; and • a service position, towards which the locking means are urged by elastic return means, and in which the locking means are interposed with contact between the external annular surface of the outer ring and the internal annular surface of the bearing support so as to prevent the bearing support and the outer ring from moving radially relative to each other.

[0011] The locking means thus allow the device to be made safe, by preventing relative radial movements between the outer ring and the bearing support in the event of a failure in the supply of lubricant to the annular damping cavity.

[0012] In preferred embodiments, the rest and service positions are such that a movement of the locking means between said positions is carried out along the axis of the bearing. In addition, the locking means, the bearing support and the outer ring are shaped to establish by wedge effect a radial contact between the locking means and each of the bearing support and the outer ring.

[0013] In preferred embodiments, the locking means are constituted by at least one of the annular sealing joints, and the latter and a bottom of said annular groove housing the latter are shaped so that: • in the rest position, a radial clearance exists between said annular sealing gasket and at least one of the external annular surface of the outer ring and the internal annular surface of the bearing support; and • in the service position, radial contact is established by wedge effect between said annular sealing joint and, on the one hand, the external annular surface of the outer ring, and, on the other hand, the internal annular surface of the bearing support.

[0014] In preferred embodiments, said annular sealing joint and the bottom of said annular groove housing the latter have respective surfaces flared in the direction of the annular damping cavity and arranged to be distant from each other, in the rest position, and to come into contact with each other, in the service position.

[0015] In preferred embodiments, the elastic return means comprise an elastic ring housed jointly in an annular groove, formed in the other of the outer annular surface of the outer ring and the inner annular surface of the bearing support, and in the annular groove housing said annular seal, where the elastic ring is interposed between said annular seal and a flank of the annular groove on a side opposite the annular damping cavity so as to be axially compressed when said annular seal is in the rest position.

[0016] In preferred embodiments, the two annular sealing gaskets are similar to each other and together constitute said locking means.

[0017] In preferred embodiments, the locking means comprise a shim arranged outside the annular damping cavity and secured to at least one piston exposed, on one axial side, to the pressure of the lubricating liquid. In addition, the elastic return means are arranged so as to act on one of the shim and the piston.

[0018] In preferred embodiments, the bearing support comprises a rim delimiting a space between itself and said internal annular surface of the bearing support. In addition, the piston axially divides said space into a first chamber, into which a passage for circulation of the lubricating liquid provided in the bearing support opens, and a second chamber, in which at least one spring is housed. compression constituting the elastic return means.

[0019] In preferred embodiments, the piston is housed in a lubricating liquid circulation passage provided in the bearing support and is connected to the shim by at least one rod extending through a corresponding axial passage, provided in the bearing support, and one end of which opens through an axial end face of the bearing support and an opposite end opens into said lubricating liquid circulation passage.

[0020] In preferred embodiments, said lubricating liquid circulation passage is connected to - or forms part of - said supply line.

[0021] In preferred embodiments, said discharge path comprises a leakage section defined between at least one of the annular seals and at least one of the outer annular surface of the outer ring and the inner annular surface of the bearing support.

[0022] In preferred embodiments, said lubricating liquid circulation passage is connected to - or forms part of - the discharge path.

[0023] In preferred embodiments, the discharge path is defined through one of the bearing bracket and the outer ring.

[0024] The invention also relates to a turbomachine for aircraft, comprising at least one shaft, and at least one device of the type described above, configured to center and guide said shaft in rotation. Brief description of the drawings

[0025] 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:

[0026] [Fig-1] is a schematic axial sectional view of an aircraft turbomachine;

[0027] [Fig.2] is a schematic axial sectional view of a device for centering and rotational guidance of a shaft in a turbomachine such as that of [Fig.l], according to a known configuration;

[0028] [Fig.3] is a schematic axial sectional view of a device for centering and rotational guidance of a shaft in a turbomachine such as that of [Fig.l], according to a preferred embodiment of the invention, the locking means of which are illustrated in a rest position;

[0029] [Fig.3A] is a partial schematic perspective view of an annular sealing gasket belonging to the device of [Fig.3];

[0030] [Fig.4] is a view similar to [Fig.3], in which the locking means are shown in a serving position;

[0031] [Fig.5] is a view similar to [Fig.3], illustrating another embodiment preferred of the invention;

[0032] [Fig.6] is a view similar to [Fig.4], illustrating the embodiment of the [Fig.5] ;

[0033] [Fig.7] is a view similar to [Fig.3], illustrating yet another mode of rea preferred embodiment of the invention;

[0034] [Fig.8] is a view similar to [Fig.4], illustrating the embodiment of the [Fig.7].

[0035] Throughout the following description and the accompanying drawings, identical reference numerals may designate similar or analogous elements. Detailed description of preferred embodiments

[0036] [Fig. 1] 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.

[0037] 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 called the “high-pressure shaft”, while the respective rotors of the low-pressure compressor and the low-pressure turbine are connected by a shaft called the “low-pressure shaft”, in a well-known manner. These rotors are rotatably mounted around an axis 28 of the turbomachine.

[0038] Throughout this description, the axial direction X is the direction of the axis 28. We also consider a first 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 flow of gases in the primary PV and secondary SV veins of the turbomachine, in the axial direction X.

[0039] The invention is, generally speaking, applicable to any type of turbomachine, whether single-flow or multi-flow, single-body or multi-body.

[0040] 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.

[0041] [Fig. 2] illustrates such a device 30 in a known configuration. The latter comprises in particular a rolling bearing 32 and a bearing support 34.

[0042] The rolling bearing 32 comprises an inner ring 36, an outer ring 38, and an annular row of rolling elements 40, such as balls or rollers, interposed between an outer annular surface 42 of the inner ring 36 and an inner annular surface 44 of the outer ring 38.

[0043] The outer ring 38 is sometimes formed of an inner annular body, which defines the inner annular surface 44, and an annular hoop mounted around the inner annular body by shrink-fitting. In other cases, as illustrated in [Fig. 2], the outer ring 38 may be made in one piece. Similarly, the bearing support 34 sometimes comprises an outer annular body and an annular hoop mounted inside the outer annular body by shrink-fitting. These different options are possible within the scope of the present invention, as will become more clearly apparent in the following.

[0044] 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.

[0045] Furthermore, the outer ring 38 has an outer annular surface 48. In addition, the bearing support 34 has an inner annular surface 50 surrounding the outer annular surface 48 of the outer ring 38.

[0046] An annular cavity called a damping cavity 52, intended to receive lubricating liquid to form a damping film or “squeeze film”, as will appear more clearly in the following, 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 55A, 55B formed in the external annular surface 48 (or, alternatively, in the internal annular surface 50).

[0047] 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 and form the aforementioned damping film therein. By “pipe”, it is generally understood, in the present description, any channel or network of channels adapted to the circulation of a liquid. The lubricant can come from any circuit or any source available for this purpose in the turbomachine. By way of illustration, the supply pipe 60 opens for example opposite an annular distribution groove 68 formed in the external annular surface 48 of the outer ring 38.

[0048] Furthermore, to allow continuous circulation of the lubricant and thus limit its heating despite the high temperatures that may prevail in the region of a bearing, in particular in cases where such a bearing is located at the level of a turbine of the turbomachine, an evacuation path is defined from the annular damping cavity 52 so as to allow the lubricating liquid to escape from the latter. Such an evacuation path is generally constituted by leakage sections provided between the annular sealing joints 54A, 54B and the external annular surface 48 of the outer ring 38 and / or the internal annular surface 50 of the bearing support 34.

[0049] The invention generally provides locking means movable between a rest position, in which the locking means are spaced from at least one of the bearing support 34 and the outer ring 38 so as to leave the latter free to move radially relative to each other, and a service position, in which the locking means are interposed between the outer annular surface 48 of the outer ring 38 and the inner annular surface 50 of the bearing support 34 while being in contact with each of these two surfaces, so as to prevent the bearing support 34 and the outer ring 38 from moving radially relative to each other.The invention provides in particular that the locking means are urged towards the rest position by the pressure of the lubricating liquid, and that they are urged towards the service position by elastic return means, as will appear more clearly in the following.

[0050] Figures 3 and 4 illustrate a first embodiment of the invention, in which the annular sealing joints 54A, 54B constitute the aforementioned locking means. Figures 3 and 4 respectively show the annular sealing joints 54A, 54B in the rest position and in the service position.

[0051] In particular, the bottom of each of the annular grooves 55A, 55B and the annular sealing joints 54A, 54B are shaped so that in the rest position, a radial clearance exists between each joint 54A, 54B and the surfaces 48 and 50 which define the cavity 52, and so that in the service position, a radial contact is established by wedge effect between each joint 54A, 54B and each of the surfaces 48 and 50.

[0052] For this purpose, the bottom of each of the annular grooves 55A, 55B has, for example, a surface 80 flared in the direction of the annular damping cavity 52 so that in the rest position, the corresponding annular sealing joint 54A, 54B is held axially at a distance from this flared surface 80 by the pressure of the lubricating liquid, and that in the service position, the corresponding annular sealing joint 54A, 54B is held axially in contact with the flared surface 80 by the elastic return means. The flared surface 80 makes it possible to radially guide the seal 54A, 54B considered up to its service position when the seal moves axially from its rest position.

[0053] More precisely, the bottom of each of the annular grooves 55A, 55B has for example a cylindrical surface 82, as well as the flared surface 80, the latter connecting the cylindrical surface 82 to a flank 84 delimiting the groove on the side of the annular damping cavity 52.

[0054] In addition, the annular sealing joints 54A, 54B advantageously each have an internal surface 86 of a shape complementary to the flared surface and arranged to come into contact with the latter in the service position.

[0055] Generally speaking, the person skilled in the art will understand that it is sufficient for one of the internal surface of a seal and the bottom of the corresponding groove to have a flared surface to allow a wedge effect to be obtained capable of allowing radial guidance of the seal towards its service position, to allow in turn the creation and elimination of a radial clearance between the seal and the surfaces 48 and 50 depending on the axial position of the seal. Alternatively, such an effect can also be obtained with a flared surface formed on the external surface of such a seal or on the internal annular surface 50 of the bearing support 34.

[0056] Furthermore, the elastic return means comprise, for each of the annular sealing joints 54A, 54B, a corresponding elastic ring 90A, 90B housed jointly in a corresponding annular groove 91A, 91B, formed in the internal annular surface 50 of the bearing support 34 (or, as a variant, in the external annular surface 48 of the outer ring 38), and in the annular groove 55A, 55B housing the annular sealing joint in question. Within the latter, the elastic ring 90A, 90B is interposed between the annular sealing joint 54A, 54B and a flank 88 delimiting the annular groove 55A, 55B on the side opposite the annular damping cavity 52, so as to be axially compressed when the annular sealing joint 54A, 54B is urged towards the rest position, and thus to urge the joint towards its service position in the direction of the annular damping cavity 52.The side 88 comprises for example a step 89 defining a receiving space for the elastic ring 90A, 90B considered.

[0057] Taking these particularities into account, the evacuation path in this embodiment is not made up of leakage sections provided at the level of the annular sealing joints 54A, 54B, but by at least one evacuation pipe 100 passing through the bearing support 34 from the annular damping cavity 52.

[0058] The evacuation pipe 100 comprises for example an annular distribution plenum 102, one or more first evacuation passages 104 connecting said plenum 102 to the annular damping cavity 52, and one or more second evacuation passages 106 connecting said plenum 102 to an environment external to the bearing support 34. The plenum 102 helps to promote the homogeneity of the lubricant flow in terms of temperature and pressure so as to optimize the efficiency of the evacuation.

[0059] The annular sealing joints 54A, 54B are therefore configured here to axially close the annular damping cavity 52 in a sealed or substantially sealed manner.

[0060] For this purpose, the seals 54A, 54B are for example of the recess type. As illustrated in [Fig.3A], such a seal is split and thus 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, typically of the order of a few tenths of a millimeter to a few millimeters, and thus maximize the sealing provided by the seal with respect to the lubricant present in the annular damping cavity 52.

[0061] In this embodiment, still with reference to Figures 3 and 4, the supply pipe 60 comprises, for example, in a similar manner, an annular distribution plenum 110, one or more distribution passages 112 connecting said plenum 110 to the annular damping cavity 52, and one or more supply passages 114 connecting said plenum 110 to a source of lubricating liquid (not visible in the figures). The plenum 110 makes it possible to promote the homogeneity of the temperature of the lubricant before the latter reaches the annular damping cavity 52.

[0062] 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 112 open, to promote homogenization of the lubricant upon its arrival in the annular damping cavity 52.

[0063] It should be noted that, in the example visible in Figures 3 and 4, the bearing support 34 comprises an external annular body 34A and an annular hoop 34B mounted inside it by hooping. These two parts are thus in contact with each other by means of two respective contact surfaces. In such a case, each of the plenums 102 and 110 is advantageously defined jointly by a groove formed in one of these contact surfaces and by the other contact surface. Such a configuration makes it easier to manufacture the bearing support 34. Alternatively, the bearing support 34 (or at least the annular portion thereof defining the internal annular surface 50) can be produced using an additive manufacturing technique.

[0064] In operation, the lubricant F ([Fig.3]) penetrates into the annular cavity damping 52 from the supply line 60 and forms a film damping within the cavity 52. ​​The lubricant circulates continuously, escaping from the cavity through the discharge pipe 100. Within the cavity 52, the pressure of the lubricant results in an axial force exerted on each of the annular sealing joints 54A, 54B, tending to push the latter axially towards the outside of the cavity 52 by axially compressing the elastic rings 90A, 90B. The annular sealing joints 54A, 54B are thus held in their respective rest positions, in which a radial clearance exists between each of the joints 54A, 54B and at least one of the surfaces 48 and 50 defining the cavity 52. ​​The joints 54A, 54B thus leave the bearing support 34 and the outer ring 38 free to move radially relative to each other, and thus allow vibration damping of these elements by compression of the damping film within the cavity 52.

[0065] If the supply of lubricating liquid is interrupted ([Fig.4]), the damping by the lubricant film within the cavity 52 no longer operates. In addition, the force induced by the pressure of the lubricant ceases to be applied to the annular sealing joints 54A, 54B, so that the latter move axially towards the inside of the cavity 52 under the effect of the stiffness of the elastic rings 90A, 90B, to their respective service positions, in which the wedge effect, produced by the shape cooperation between the internal surface of each of the joints 54A, 54B and the bottom of the corresponding annular groove 55A, 55B, guides each of the joints 54A, 54B until it establishes radial contact with the two surfaces 48 and 50 defining the cavity 52, for example by means of the flared surfaces 80 formed respectively at the bottom of the annular grooves 55A, 55B and the complementary surfaces 86 of the joints.Such radial contact prevents relative radial displacements between the bearing support 34 and the outer ring 38 and thus limits the risks of damage to the device 30.

[0066] In other embodiments which will be described with reference to Figures 5 to 8, the locking means are not constituted by the annular sealing joints 54A, 54B but by a shim 130 arranged outside the annular damping cavity 52 and secured to at least one piston 132 exposed, on one axial side, to the pressure of the lubricating liquid. In addition, the elastic return means are arranged so as to act on one of the shim 130 and the piston 132.

[0067] More specifically, in the embodiment of Figures 5 and 6, the bearing support 34 comprises a rim 140, for example of annular shape, extending axially in the direction of the cavity 52 from a radial end wall 142 of the bearing support 34, so that the rim 140 delimits, between itself and the internal annular surface 50 of the bearing support, a space 144 for example also of annular shape. The latter is for example closed axially by the radial end wall 142, on a side opposite the cavity 52, and by a partition 146 for example also of annular shape, on the side of cavity 52.

[0068] In addition, the piston 132 axially divides the space 144 into two chambers 150 and 154. A first of these chambers 150 is for example defined between the piston 132 and the partition 146 so as to receive lubricating liquid through a circulation passage 152 formed in the bearing support 34 and for example connected to the supply pipe 60, in this case to an annular distribution plenum 110. The second chamber 154 is for example defined between the piston 132 and the radial end wall 142. In this second chamber 154 is housed at least one compression spring 156, constituting the elastic return means, and for example interposed between the piston 132 and the radial end wall 142.

[0069] The shim 130 is arranged axially between the partition 146 and one of the annular sealing joints 54A, 54B, and is rigidly connected to the piston 132 by a rod 160 which passes through the partition 146 in a sealed manner.

[0070] In the rest position visible in [Fig. 5], the shim 130 is arranged axially beyond one end of the outer ring 38 so as not to be interposed between the latter and the bearing support 34. For example, the shim 130 is housed at one end of the space defined between the rim 140 and the internal annular surface 150 of the bearing support, beyond the partition 146 in the direction of the damping cavity 52.

[0071] In the service position visible in [Fig.6], the shim 130 is offset towards the cavity 52 so as to be interposed between the outer ring 38 and the bearing support 34.

[0072] For this purpose, in the example illustrated, the external annular surface 48 of the outer ring 38 has, at its end located on the side of the shim 130, an annular portion 162 of flared shape in the direction of the damping cavity 52 to cooperate by wedge effect with the shim 130, as will appear more clearly in the following.

[0073] Generally, the shim 130 may extend over 360 degrees around the axis 46 or have a limited circumferential extent, in which case the locking means advantageously comprise a plurality of such shims 130 distributed around the axis 46. Similarly, the piston 132 may extend over 360 degrees around the axis 46 or have a limited circumferential extent, in which case a plurality of such pistons 132 may be provided to correspond, where appropriate, to the plurality of shims 130. In the case of an annular shim 130 and an annular piston 132, the latter are advantageously connected to each other by a plurality of rods such as the rod 160, distributed around the axis 46. In the case of a plurality of shims and a plurality of pistons, synchronization means are advantageously provided for synchronize the axial movement of the pistons and shims. Furthermore, in the case of non-annular piston(s), additional partitions are provided to circumferentially delimit the chambers 150 and 154. In such a case, the rim 140 may also have a limited circumferential extent, i.e. not be annular in shape.

[0074] Furthermore, in the example illustrated, the evacuation path consists of leakage sections 164 provided between the annular sealing joints 54A, 54B and the external annular surface 48 of the outer ring 38 and / or the internal annular surface 50 of the bearing support 34.

[0075] In operation, the lubricant F ([Fig. 5]) enters the annular damping cavity 52 from the supply pipe 60 and forms a damping film within the cavity 52. ​​The lubricant circulates continuously, escaping from the cavity via the discharge path, in this case via the leakage sections provided at the annular sealing joints 54A, 54B. Furthermore, a portion of the lubricant from the supply pipe 60 enters the first chamber 150 via the circulation passage 152. Within the first chamber 150, the pressure of the lubricant results in an axial force exerted on the piston 132 in the direction opposite to the cavity 52, thus tending to keep the piston 132 and therefore also the shim 130 away from the cavity 52, axially compressing the compression spring 156.The shim 130 is thus maintained in its rest position and thus leaves the bearing support 34 and the outer ring 38 free to move radially relative to each other, thus allowing vibration damping of these elements by compression of the damping film within the cavity 52.

[0076] If the supply of lubricating liquid is interrupted ([Fig. 6]), the damping by the lubricant film within the cavity 52 no longer operates. In addition, the first chamber 150 ceases to be supplied with lubricant, so that no force opposes the thrust of the compression spring 156 on the piston 132. The latter thus moves axially towards the cavity 52, carrying with it the shim 130, to the service position of the latter. The wedge effect produced by the contact between the flared annular portion 162 and the shim 130 guides the latter until it establishes radial contact with the two surfaces 48 and 50 which define the cavity 52. ​​Such radial contact prevents relative radial movements between the bearing support 34 and the outer ring 38 and thus limits the risks of damage to the device 30.

[0077] In the embodiment of Figures 7 and 8, the piston 132 is housed in a circulation passage 170 for the lubricating liquid provided in the bearing support 34. This passage is for example part of the aforementioned discharge path, in which case the annular sealing joints 54A, 54B are advantageously configured to axially close the annular damping cavity 52 in a sealed or substantially sealed manner. Alternatively, the circulation passage 170 may be part of the pipe power supply 60.

[0078] The piston 132 is connected to the shim 130 by at least one rod 172 extending through a corresponding axial passage 174, formed in the bearing support 34, and one end of which opens through an axial end face 176 of the bearing support while an opposite end opens into the circulation passage 170. Sealing means are provided between the rod 172 and the bearing support 34 to prevent the lubricating liquid present in the circulation passage 170 from escaping through the axial passage 174. In the example illustrated, guide bearings 178 are further provided to guide the rod 172 in axial translation.

[0079] In addition, the elastic return means, which take the form of, for example, leaf springs 180, are for example interposed between the axial end face 176 of the bearing support and a radial wall 182 connecting the shim 130 to the rod 172. These leaf springs 180 are configured to exert a return force axially towards the cavity 52 when the shim 130 is in its rest position ([Fig.7]).

[0080] Generally, as in the embodiment of Figures 5 and 6, the wedge 130 can extend over 360 degrees around the axis 46 or have a limited circumferential extent, in which case the locking means advantageously comprise a plurality of such wedges 130 distributed around the axis 46. In the case of a plurality of wedges, synchronization means are advantageously provided to synchronize the axial movement of the wedges.

[0081] In addition, a plurality of pistons such as the piston 132 may be provided to be housed respectively in a plurality of circulation passages such as the circulation passage 170, distributed around the axis 46. These pistons may be connected to the same annular wedge 130, or be connected respectively to a plurality of wedges each of limited circumferential extent.

[0082] In the rest position visible in [Fig.7], the shim 130 is arranged axially beyond one end of the outer ring 38 so as not to come between the latter and the bearing support 34.

[0083] In the service position visible in [Fig.8], the shim 130 is offset towards the cavity 52 so as to be interposed between the outer ring 38 and the bearing support 34.

[0084] To guide the shim 130 radially towards its service position when the shim moves axially towards the cavity 52, in the example illustrated, the external annular surface 48 of the outer ring 38 has, at its end located on the side of the shim 130, an annular portion 162 of a flared shape in the direction of the damping cavity 52 and forming for example a chamfer or a rounding, and the shim 130 has a flared internal surface 190, for example also in the form of a chamfer or a rounding, so that the two aforementioned flared surfaces 162 and 190 cooperate by wedge effect.

[0085] In operation, the lubricant F ([Fig.7]) enters the annular damping cavity 52 from the supply pipe 60 and forms a damping film within the cavity 52. ​​The lubricant circulates continuously, escaping from the cavity via the discharge path, in this case via the circulation passage 170. Within this circulation passage 170, the pressure of the lubricant results in an axial force exerted on the piston 132 in the axial direction opposite to the cavity 52, thus tending to keep the piston 132 and therefore also the shim 130 away from the cavity 52, against the axial force exerted by the leaf springs 180. The shim 130 is thus held in its rest position and thus leaves the bearing support 34 and the outer ring 38 free to move radially relative to each other, thus allowing vibration damping of these elements by compression of the damping film within the cavity 52..

[0086] If the supply of lubricating liquid is interrupted ([Fig. 8]), the damping by the lubricant film within the cavity 52 no longer operates. In addition, the circulation passage 170 ceases to be supplied with lubricant, so that no force opposes the traction exerted by the springs 180 on the radial wall 182. The latter thus moves axially towards the cavity 52, carrying with it the shim 130, until it reaches the service position of the latter. The wedging effect produced by the contact between the two flared surfaces 162 and 190 causes the shim 130 to establish radial contact with the two surfaces 48 and 50 which define the cavity 52. ​​Such radial contact prevents, here again, relative radial movements between the bearing support 34 and the outer ring 38, and thus limits the risks of damage to the device 30.

Claims

1. Claims 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) housed in respective annular grooves (55A, 55B) each formed in one of the outer annular surface (48) of the outer ring (38) and the inner annular surface (50) of the bearing support (34); • 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 (F) to form a damping film therein; • an evacuation path (100, 164) defined from the annular damping cavity (52) so as to allow the lubricating liquid to escape from the latter; characterized in that it comprises locking means movable between: • a rest position, towards which the locking means are urged by the pressure of the lubricating liquid, and in which the locking means are spaced from at least one of the bearing support (34) and the outer ring (38) of so as to leave the latter free to move radially relative to each other; and • a service position, towards which the locking means are urged by elastic return means, and in which the locking means are interposed with contact between the external annular surface (48) of the outer ring (38) and the internal annular surface (50) of the bearing support (34) so ​​as to prevent the bearing support (34) and the outer ring (38) from moving radially relative to each other.

2. Device according to claim 1, in which the rest and service positions are such that a movement of the locking means between said positions takes place along the axis (46) of the bearing, and in which the locking means, the bearing support (34) and the outer ring (38) are shaped to establish by wedge effect a radial contact between the locking means and each of the bearing support (34) and the outer ring (38).

3. Device according to claim 2, in which the locking means are constituted by at least one of the annular sealing joints (54A, 54B), and in which the latter and a bottom of said annular groove (55A, 55B) housing the latter are shaped so that: • in the rest position, a radial clearance exists between said annular sealing joint (54A, 54B) and at least one of the external annular surface (48) of the outer ring (38) and the internal annular surface (50) of the bearing support (34); and • in the service position, the radial contact is established by wedge effect between said annular sealing joint (54A, 54B) and, on the one hand, the external annular surface (48) of the outer ring (38), and, on the other hand, the internal annular surface (50) of the bearing support (34).

4. Device according to claim 3, in which said annular sealing gasket (54A, 54B) and the bottom of said annular groove (55A, 55B) housing the latter have respective surfaces (86, 80) flared in the direction of the annular damping cavity (52) and arranged to be distant from each other, in the rest position, and to come into contact with each other, in the service position.

5. A device according to claim 3 or 4, wherein the elastic return means comprise an elastic ring (90A, 90B) housed jointly in an annular groove (91A, 91B), formed in the other of the outer annular surface (48) of the outer ring (38) and the inner annular surface (50) of the bearing support (34), and in the annular groove (55A, 55B) housing said annular seal (54A, 54B), wherein the elastic ring (90A, 90B) is interposed between said annular seal and a flank (88) of the annular groove (55A, 55B) on a side opposite the annular damping cavity (52) so as to be axially compressed when said annular seal is in the rest position.

6. Device according to any one of claims 3 to 5, in which the two annular sealing gaskets (54A, 54B) are similar to each other and together constitute said locking means.

7. Device according to claim 1 or 2, in which the locking means comprise a shim (130) arranged outside the annular damping cavity (52) and secured to at least one piston (132) exposed, on one axial side, to the pressure of the lubricating liquid, and in which the elastic return means are arranged so as to act on one of the shim (130) and the piston (132).

8. Device according to claim 7, in which the bearing support (34) comprises a rim (140) delimiting a space (144) between itself and said internal annular surface (50) of the bearing support, and in which the piston (132) axially divides said space (144) into a first chamber (150), into which opens a circulation passage (152) of the lubricating liquid formed in the bearing support (34), and a second chamber (154), in which is housed at least one compression spring (156) constituting the elastic return means.

9. Device according to claim 7, in which the piston (132) is housed in a circulation passage (170) for the lubricating liquid provided in the bearing support (34) and is connected to the shim (130) by at least one rod (172) extending through a corresponding axial passage (174), provided in the bearing support (34), and one end of which opens through an axial end face (176) of the bearing support and an opposite end opens into said circulation passage (170) for the lubricating liquid.

10. Device according to claim 8 or 9, wherein said circulation passage (152, 170) of the lubricating liquid is connected to - or forms part of - said supply pipe (60).

11. The device of claim 10, wherein said discharge path comprises a leakage section (164) defined between at least one of the annular seals (54A, 54B) and at least one of the outer annular surface (48) of the outer ring (38) and the inner annular surface (50) of the bearing support (34).

12. Device according to claim 8 or 9, wherein said circulation passage (152, 170) of the lubricating liquid is connected to - or forms part of - the discharge path.

13. A device according to any one of claims 1 to 12, wherein the discharge path is defined through one of the bearing support (34) and the outer ring (38).

14. Turbomachine for aircraft, comprising at least one shaft, and at least one device according to any one of claims 1 to 13, configured to center and guide said shaft in rotation.

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