FAN MODULE EQUIPPED WITH AN OIL TRANSFER DEVICE

Description

Technical field of the invention

[0001] The present invention relates to a blower module for an aircraft turbomachine, this module comprising an oil transfer device. Technical background

[0002] An aircraft turbomachine classically comprises a gas generator including, from upstream to downstream according to the direction of gas flow in operation, at least one compressor, an annular combustion chamber and at least one turbine.

[0003] The gases entering the gas generator are compressed in the compressor(s), then mixed with fuel and burned in the combustion chamber. The combustion gases flow and expand in the turbine(s) to drive its rotor(s).

[0004] In the case of a twin-body turbomachine, respectively low pressure and high pressure, the rotor of the high-pressure turbine is connected by a high-pressure shaft to the rotor of the high-pressure compressor, and the rotor of the low-pressure turbine is connected by a low-pressure shaft to the rotor of the low-pressure compressor.

[0005] The turbomachine can be equipped with one or more propellers, shrouded or unshrouded. In the case of a shrouded propeller located upstream of the gas generator, this propeller is called a fan and is driven by the low-pressure shaft of the gas generator.

[0006] The blower generates a flow of gas in operation which is divided into a first flow, called the primary flow which flows into the gas generator as mentioned above, and a second flow, called the secondary flow, which flows around the gas generator.

[0007] The dilution ratio, which is the ratio between the secondary flow rate and the primary flow rate, is increasingly important in modern turbomachinery, resulting in an increase in the diameter of the blower and a decrease in the diameter of the gas generator.

[0008] To limit the rotational speed of the fan, particularly in turbomachinery with high bypass ratios, it is common practice to drive the fan via a reduction gear, generally of the epicyclic or planetary type. The low-pressure shaft thus drives the fan through the reduction gear.

[0009] A fan, or a propeller in general, may include variable-pitch blades, meaning that each blade has an orientation around a radial axis that can be precisely adjusted. The blades are supported by a polygonal ring-shaped hub and are rotated around these axes by means of a common hydraulic actuator mounted inside the hub. This actuator is oil-supplied and can be positioned in a rotating frame of reference when it is rotationally fixed to the hub and the fan.

[0010] The turbomachine includes a lubrication system comprising an oil reservoir and a pump, which is generally located in a fixed frame. It follows, therefore, that the oil supply to the actuator from the lubrication system must be achieved via an oil transfer device from a fixed frame to a rotating frame. Such a device is commonly called an OTB, an acronym for the Anglo-Saxon term. Oil Transfer Bearing.

[0011] This type of device can be mounted in a turbomachine with a fan of the aforementioned type to supply oil to the actuator and also to supply lubricating oil to the gearbox. This type of device can also be mounted in another type of turbomachine, such as, for example, a turbomachine equipped with an unfaired, variable-pitch propeller, of the turboprop type.

[0012] In current technology, an oil transfer device comprises a stator ring having an internal cylindrical surface and internal oil channels, each opening onto this internal cylindrical surface. These channels are connected by lines to the aforementioned lubrication system.

[0013] The device further includes a shaft engaged in the ring and free to rotate about an axis inside the ring. The shaft has an external cylindrical surface extending inside the internal cylindrical surface of the ring, and internal oil channels, each opening onto this external cylindrical surface. These channels are connected by lines to the actuator for its oil supply.

[0014] In current technology, the outer cylindrical surface of the shaft has annular grooves for housing annular sealing segments. These segments are designed to move within the grooves and are configured to bear radially against the inner surface of the ring to limit and control oil leakage. The outlets of the aforementioned channels are located between two adjacent segments, thus ensuring that a maximum amount of oil supplied by each channel on the ring feeds a corresponding channel on the shaft. The number of segments is twice the number of channels. Document GB-A-824,332 describes an oil transfer device of this type.

[0015] However, this technology is unsatisfactory for several reasons. Deformations during operation (related to differential thermal expansion and stress) and manufacturing and assembly tolerances make it difficult to precisely control these leaks. The device comprises numerous parts, which complicates assembly. Manufacturing and assembling such a device is therefore relatively time-consuming and expensive. Furthermore, the greater the number of pipes in the device and the greater the number of sealing segments, the larger the axial dimension and therefore the axial footprint of the device must be to accommodate these various segments. An oil transfer device can be complex to integrate into a turbomachine due to its size.Finally, the lifespan of such a device is generally limited due to potential misalignments between the shaft and the ring during operation, and wear on the sealing segments, which can be exacerbated by these misalignments as well as by the shaft's rotational speed. The larger the diameter of the device, the greater the shaft's peripheral speed and the wear on the segments.

[0016] It would be advantageous to incorporate a plain bearing between the ring and shaft surfaces. One solution would be to mount a first ring on the inner surface of the ring and a second ring on the outer surface of the shaft, so that these rings define the plain bearing. These rings would then include oil passages in fluid communication with the oil lines of the ring and shaft, in order to supply oil to the plain bearing. To maintain clearance between the rings and prevent misalignment, it might also be useful to provide roller bearings on either side of the plain bearing, with their inner and outer rings mounted on the shaft and ring, respectively.

[0017] However, this solution would not be satisfactory because the number of parts in the transfer device would be significant (bearings with rollers and bushings, rings, etc.) and assembling the device would be complex and costly. The invention therefore proposes an improved oil transfer device that solves all or part of the problems of the prior art.

[0018] Prior art also includes documents GB-A-824332, US-A1-2004 / 037483, EP-A1-3179044, WO-A1-2015 / 102779, WO-A2-2013 / 011225 and EP-A1-3138771. Summary of the invention

[0019] The invention relates to a fan module for an aircraft turbomachine, this module comprising a fan which includes a fan shaft and variable-pitch fan blades, and an oil transfer device configured to ensure oil transfer between a stator and an actuator which is rotationally fixed to the fan shaft and which is configured to control the fan blade pitch, this device comprising: a stator ring comprising a first cylindrical surface, for example internal, and internal oil channels each opening onto said first cylindrical surface, and a shaft engaged in or on said ring and comprising a second cylindrical surface extending inside or around said first cylindrical surface, the shaft comprising internal oil channels each opening onto said second cylindrical surface, characterized in that it further comprises: a plain bearing located between said first and second cylindrical surfaces, and rolling bearings mounted between the ring and the shaft, on either side of the plain bearing, each of these rolling bearings having rolling elements between two annular raceways, in that one of the elements chosen from the ring and the shaft carries bushings defining the first raceways of the rolling bearings, the second raceways of these rolling bearings being integrated into the other of these elements, and in that the plain bearing is made by a single ring interposed between the first and second cylindrical surfaces, and fixed to one of said elements. The invention thus proposes an oil transfer device without sealing components or segments between the cylindrical surfaces opposite the stator ring and the shaft. Instead, a plain bearing is provided between these surfaces.Rolling bearings are mounted on either side of this plain bearing to ensure the radial thickness of the plain bearing remains constant regardless of the turbomachine's speed and the peripheral speed of the transfer device shaft. The rolling bearings are automatically lubricated by the oil that leaks from the plain bearing during operation. Furthermore, the rolling bearings limit oil leakage outside the plain bearing and the device. In addition, the rolling bearings eliminate the risk of misalignment between the ring and the shaft, thus preventing contact and wear. The sealing segments are therefore no longer considered wear parts of the device, resulting in an optimized service life compared to previous designs.

[0020] Furthermore, the number of parts in the device is reduced by using a single flange instead of two and by using roller bearings with bushings integrated into the ring or shaft. This minimizes the need for assembly and machining tolerances. The invention facilitates the manufacturing and assembly of the device.

[0021] The module according to the invention may comprise one or more of the following features, taken individually or in combination with each other: - The bearings are roller bearings; one element carries the bearing rings and the cage; the cage has two cylindrical surfaces extending around each other, including a cylindrical shrink-fit surface and a cylindrical centering surface, this cylindrical centering surface having a diameter equal to the diameters of the second raceways; the stator ring carries the rings and the cage; the bearing rings have identical internal diameters; one element carries the rings and the other element carries the cage; the ring carries the cage and the shaft carries the rings; the cage has two cylindrical surfaces extending around each other, including a cylindrical shrink-fit surface on the ring and a cylindrical centering surface on the shaft.the bearing rings having different internal diameters from each other and different from the diameter of the internal cylindrical surface of the ferrule; the ferrule includes orifices which are located on one side opposite the outlets of the pipes of one of the elements, and which are in fluidic communication with the pipes of the other element via annular grooves formed at the outlets of the pipes of this other element; the blower is driven in rotation by a gearbox, said device being mounted upstream of the gearbox and being configured to supply oil to the gearbox as well as the actuator and possibly also the gearbox; the blower is driven by the blower shaft which is guided by bearings and which is coupled to the shaft of the device; the gearbox is of the planetary type, that is to say, with a planet carrier fixed in rotation and therefore with a rotating ring gear.-- The gearbox is of the epicyclic type, i.e., with a fixed ring gear and therefore a rotating planet carrier; -- The device supplies the gearbox with lubricating oil, and in particular at least part of its bearings and gears; -- The device is configured to supply the actuator with oil at a pressure between 2 and 200 bar, and preferably between 5 and 130 bar; -- The device is configured to supply the gearbox with oil at a pressure between 2 and 50 bar, and preferably between 5 and 20 bar. The invention also relates to an aircraft turbomachine, comprising a module as described above. Brief description of the figures

[0022] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which: [ Fig.1 ] there figure 1is a schematic half-view in axial cross-section of a turbomachine equipped with an oil transfer device, [ Fig. 2 ] there figure 2 is a larger-scale view of a part of the figure 1 , [ Fig.3 ] there figure 3 is a schematic half-view in axial cross-section of an oil transfer device according to the prior art, [ Fig. 4 ] there figure 4 is a schematic half-view in axial cross-section of an oil transfer device according to a first embodiment of the invention, and [ Fig. 5 ] there figure 5 is a schematic half view in axial section of an oil transfer device according to a second embodiment of the invention. Detailed description of the invention

[0023] There figure 1shows a turbomachine 10 which includes, in a conventional manner, a blower 12, a low pressure (LP) compressor 14, a high pressure (HP) compressor 16, an annular combustion chamber 18, a high pressure (HP) turbine 20, a low pressure (LP) turbine 22 and an exhaust nozzle 24.

[0024] The rotors of the high-pressure compressor 16 and the high-pressure turbine 20 are connected to each other by a high-pressure shaft 26 and together form a high-pressure (HP) housing which is guided in rotation around the longitudinal axis A of the turbomachine by roller bearings 28, 30. A first bearing 28 is mounted between an upstream end of the shaft 26 and the HP housing and an inter-compressor housing 32 located between the LP compressors 14 and HP 16. A second bearing 30 is mounted between a downstream end of the shaft 26 and the HP housing and an inter-turbine housing 34 located between the LP turbines 22 and HP 24.

[0025] The rotors of the compressor BP 14 and the turbine BP 22 are connected by a low-pressure shaft 36 and together form a low-pressure (LP) unit which is guided in rotation around the longitudinal axis A of the turbomachine by roller bearings 38, 40. At least one bearing 38 is mounted between an upstream end of the shaft 36 and the LP unit and an inlet housing 42 located upstream of the compressor BP 14. Other bearings 40 are mounted between a downstream end of the shaft 36 and the LP unit and an exhaust housing 44 located downstream of the turbine BP 22.

[0026] The blower 12 is driven by a blower shaft 46 which is driven by the BP shaft 36 by means of a reducer 48. This reducer 48 is generally of the planetary or epicyclic type.

[0027] The following description concerns a planetary type reducer, in which the planet carrier and the sun are mobile in rotation, the ring gear of the reducer being fixed in the frame of the motor.

[0028] The gearbox 48 is positioned in the upstream part of the turbomachine. A fixed structure schematically comprising, here, an upstream part 50a and a downstream part 50b which make up the motor or stator housing 50 is arranged to form an enclosure E surrounding the gearbox 48. This enclosure E is closed upstream by a seal 52 at the level of a bearing 54 allowing the passage of the blower shaft 46, and downstream by a seal 55 at the level of the bearing 38 allowing the passage of the BP shaft 36.

[0029] The enclosure E is located inside the inlet casing 42 which is situated between an inlet rectifier blade 56 and the compressor BP 14.

[0030] There figure 2 shows the reducer 48 on a larger scale.

[0031] The reducer 48 includes a solar 48a centered on the axis A and coupled to the shaft BP 36 for example via splines.

[0032] The reducer 48 includes a ring gear 48b which is free to rotate about axis A and is connected to the blower shaft 46 for its rotational drive. The ring gear 48b is guided by two bearings 54, 58 supported by the input housing 42, these bearings 54, 58 being located upstream of the reducer 48.

[0033] The reduction gear 48 finally includes satellites 48c which are arranged around the axis A and meshed with the solar element 48a and the ring gear 48b. These satellites 48c are carried by a satellite carrier 48d which is fixed to the inlet housing 42. The blower 12 of the figure 1includes variable pitch blades 12a and is associated with an actuator 62 which allows centrally control of the positioning of the blades 12a around their axes B, which are generally radial axes relative to the axis A of the turbomachine.

[0034] Each of the blades 12a includes a foot 12b forming a pivot which is housed in a housing of a polygonal ring-shaped hub 64, and which is connected by a linkage system 66 to a piston of the actuator 62.

[0035] The actuator 62 extends along the axis A and its piston is movable in translation along this axis, for example from a first position in which the blades 12a are feathered to a second position in which the blades 12a obstruct the passage of air through the blower 12.

[0036] The airflow F1 passing through the fan 12 is split into two annular and coaxial flows downstream of the fan by an annular separator 68 that extends around the blade 56. A first airflow, called the primary flow F2, flows in a primary channel, passes through this blade 56, and enters the compressors 14 and 16 to be compressed. This compressed air is then mixed with fuel and burned in the combustion chamber 18. The combustion gases are then expanded in the turbines 20 and 22 to drive their rotors and the LP 36 and HP 26 shafts, and then flow into the nozzle 24.

[0037] A second airflow, called the secondary flow F3, flows in a secondary channel defined internally by an annular engine casing 70 extending longitudinally around the compressors 14, 16, the combustion chamber 18, and the turbines 20, 22, and externally by an annular nacelle casing 72 extending longitudinally around the fan 12 and part of the engine. This nacelle casing 72 is connected to the engine by outlet guide vanes 42a of the inlet casing 42. These guide vanes 42a are structural and are configured to straighten the airflow exiting the fan 12.

[0038] The actuator 62 is hydraulic and operates with a fluid, oil, which comes from a lubrication system generally located in the nacelle or between the compressors 14, 16 and the crankcase 70 (i.e., in the engine) and therefore in a fixed frame of reference of the turbomachine. In contrast, the actuator 62 is located in a rotating frame of reference.

[0039] As can be seen in the figure 2 , the turbomachine 10 includes a device 74 for transferring oil from the fixed reference frame of the engine to the rotating reference frame in which the actuator 62 is located.

[0040] In the example shown, the device 74 is located upstream of the reducer 48 and includes one or more oil supply routes 76 to supply the actuator 62 and possibly also to lubricate the reducer 48.

[0041] The dotted line of the figure 2 symbolizes one of these paths along its entire course, from the fixed reference point to the actuator 62: crossing the primary vein to the device 74, crossing the reducer 48 (between its satellites or through the axes of these satellites), and path along the satellite carrier and then the blower shaft 46.

[0042] There figure 3 illustrates an oil transfer device 74 which includes: a stator ring 80 having an internal cylindrical surface 80a and internal oil channels 80b each opening onto said internal cylindrical surface 80a, a shaft 82 engaged in the stator ring 80 and movable in rotation about the axis A inside this ring 80, the shaft 82 having an external cylindrical surface 82a extending inside the surface 80a, and internal oil channels 82b each opening onto the surface 82a.

[0043] A plain bearing P is arranged between surfaces 80a, 82a. For this, a first fret 84a is mounted in the ring 80 and covers its internal surface 80a, and a second fret 84b is mounted on the shaft 82 and covers its external surface 82a.

[0044] The rings allow for precise machining of the plain bearing surfaces, a task that is more difficult when performed directly on a workpiece, particularly inside the ring. These rings 84a, 84b define the plain bearing P and include oil passages 86 in fluidic communication with the channels 80b, 82b of the ring 80 and the shaft 82, in order to supply oil to the plain bearing P.

[0045] Bearings 88, 90 are mounted between the ring 80 and the shaft, 82, on either side of the plain bearing P. Each of these bearings 88, 90 comprises an inner ring 88a, 90a which is mounted on the fret 84b and an outer ring 88b, 90b which is mounted in the ring 80.

[0046] This technology presents many problems, as described above.

[0047] The present invention makes it possible to remedy all or part of these problems by means of an oil transfer device, a first embodiment of which is illustrated in the figure 4 .

[0048] The reference figures used above to designate certain elements are repeated in the description that follows and in Figures 6 and 7 insofar as they designate these same elements.

[0049] The oil transfer device 174 of the figure 4 also includes a stator ring 180 and a shaft 182 engaged in the stator ring 180 and movable in rotation about the axis A inside this ring 180.

[0050] The ring 180 has an internal cylindrical surface 180a and internal oil channels 180b, each opening onto the surface 180a. The channels 180b are all radially oriented and arranged one behind the other along the axis A. There are three of them in the example shown.

[0051] Although the pipes 180b are shown here in the same axial plane, they could be located in different axial planes. This depends in particular on the conduits 192 to which they are connected and the arms 42b through which these conduits pass. In yet another variant, the pipes 180b could have radially external ends located in the same axial plane and ends distributed angularly around axis A and opening onto surface 180a.

[0052] Each of the pipes 180b comprises a radially internal end that forms the aforementioned outlet and a radially external end that forms a port 190 for connection to an oil line 192. The port 190 forms a female part, and one end of the line 192 forms a male part that is sealed into the port 190. These lines 192 are designed to pass through the stator of the gearbox 48, the tubular arms 42b of the inlet housing 42 located in the primary flow path F2, and then the guide vanes 42a located in the secondary flow path F3, to reach the lubrication system located in the nacelle (see figure 1 ). An alternative is to mount the lubrication system in the engine (between the primary flow - compressors 14 and 16) and the crankcase 70 of the secondary flow, so that these lines 192 do not cross the secondary flow F3.

[0053] The ring 180 has a general cylindrical shape and includes an upstream cylindrical rim 200a and a downstream cylindrical rim 200b. These rims 200a, 200b have identical or similar diameters.

[0054] As schematically represented in the figure 2 , the ring 180 can be connected by a flexible link to the satellite carrier 48d. In the example shown, this flexible link includes a bellows-shaped wall 202.

[0055] A ring 204 is fixed inside the ring 180 so as to cover its surface 180a. This ring 204 extends over most of the length of the ring 180 and includes an annular flange 204a radially external at its upstream end, which bears axially against a cylindrical bearing surface of the ring 180. As its name indicates, the ring 204 is shrink-fitted into the ring 180. The shrink-fitting, combined with the support of its flange 204a, secures the ring 204 to the ring 180.

[0056] The ring 204 comprises an annular row of radial orifices 206 at each of the channels 180b. Furthermore, an annular groove 208 is formed on the inner periphery of the ring 180 and at each of the channels 180b, this groove 208 being closed internally by the ring 204. It is therefore understood that each channel 180b supplies a groove 208 and that each groove 208 distributes oil to the orifices 206 of the ring 204.

[0057] The fret 204 includes an external cylindrical shrink-fit surface which is in contact with the internal surface 180a of the ring 180, and an internal cylindrical centering surface intended to be separated by a predetermined radial distance from the external surface 182a of the shaft 182 to define the plain bearing P.

[0058] Shaft 182 does not have a fret. This removal reduces the number of tolerance stacking interfaces by three. Consequently, the resulting clearance tolerance is significantly reduced by decreasing the number of contributing factors, and therefore the resulting clearances are reduced, particularly between the rotor and stator.

[0059] The shaft 182 has an external cylindrical surface 182a extending inside the surface 180a and internal oil channels 182b each opening onto the surface 182a. The channels 182b are all radially oriented and arranged one behind the other along the axis A. There are three of them in the example shown.

[0060] An annular groove 210 is formed at the outer periphery of the shaft 182 and at the right of each of the pipes 182b.

[0061] Each of the pipes 182b is connected to a conduit 212 which can be integrated into the shaft 182. The conduits 212 extend axially in the shaft 182 and each of these conduits 212 includes a downstream end connected to one of the pipes 182b. The upstream ends of the conduits 212 open upstream of the shaft 182 and one of these conduits 212, for example the one visible in section in the figures, is for example connected to the aforementioned actuator 62.

[0062] A first bearing 220 is mounted between the rim 200b of the ring 180 and the downstream end of the shaft 182.

[0063] The 220 bearing here is a rolling bearing and includes rollers which are arranged between two raceways, respectively internal and external.

[0064] The internal raceway of bearing 220 is integrated into shaft 182, that is to say there is no internal ring added to shaft 182 for bearing 220.

[0065] The outer raceway of the bearing 220 is formed by an outer ring 224 mounted inside the flange 200b. This ring 224 bears axially on a cylindrical surface on the inner periphery of the flange 200b, located upstream. Downstream, the ring 224 is axially retained by a nut 226 screwed into the inner periphery of the flange 200b or by a retaining ring engaged in this flange.

[0066] The internal raceway of bearing 230 is integrated into shaft 182, that is to say there is also no internal ring added to shaft 182 for bearing 230.

[0067] The outer raceway of the bearing 230 is formed by an outer ring 234 mounted inside the flange 200a. This ring 234 bears axially on a cylindrical surface on the inner periphery of the flange 200a, located downstream. Upstream, the ring 234 is axially retained by a nut 228 screwed into the inner periphery of the flange 200a or by a retaining ring engaged in this flange.

[0068] Advantageously, as can be seen in the figure 4 The external surface 182a of the shaft 182 and the internal raceways of the bearings 220 (integrated into the shaft 182) have the same diameter D1 and extend continuously from one another. It is thus understood that the shaft 182 can be mounted inside the ring 180 by axial translation, the ring 180 being able to be pre-equipped with the sleeve 204 and the bushings 224, 234 and the rollers of the bearings 220, 230 just before this translation.

[0069] A second embodiment of the invention is shown in the figure 5 This embodiment is very close to the previous embodiment and differs essentially in that the external bearing tracks of the bearings 220, 230 are integrated into the ring 180 and, on the contrary, the internal bearing tracks of these bearings are formed by internal rings 224', 234' mounted on the shaft 182.

[0070] The upstream bearing 230 has an external diameter D3 defined by the raceway integrated into the ring 180, and an internal diameter D3' defined by the inner ring 234'. The downstream bearing 220 has an external diameter D4 defined by the raceway integrated into the ring 180, and an internal diameter D4' defined by the inner ring 224'.

[0071] In the example shown, D2 is between D3 and D3', and D2 is less than D4 and D4'. Furthermore, D3' < D4' < D3 < D4.

[0072] It can thus be seen that the shaft 182 is stepped and includes sections of different diameters on which the rings 224', 234' of the bearings 220, 230 are mounted and around which the sleeve 204 extends. The shaft 182 includes an upstream section T1 of smaller diameter D3' for the mounting of the bearing 230, an intermediate section of diameter D2 for the formation of the plain bearing P, and a downstream section of diameter D4' for the mounting of the bearing 220.

[0073] Similarly, the ring 180 is stepped and includes sections of different internal diameters in which the bearings 220, 230 and the fret 204 are mounted. The cylindrical rims 200a, 200b thus have different internal diameters.

[0074] This embodiment reduces the number of tolerance contributors. Consequently, the resulting clearance tolerance is significantly reduced by decreasing the number of contributors, and therefore the resulting clearances are reduced, particularly between the rotor and stator.

[0075] In the example shown of the figures 2 And 5 , we observe that the blower 12 is driven by a shaft 46 which is guided by bearings 54, 58 and which is coupled to the shaft 182 of the device 174.

[0076] Device 174 of the figure 5can be mounted in the following way. The ring 224' and the rollers of the bearing 220 are first mounted on the shaft 182 by axial translation from the upstream end until they reach an axial stop against a cylindrical shoulder of the shaft 182. The shaft 182 is then engaged in the ring 180 by axial translation from the downstream end until the rollers of the bearing 220 are engaged in the flange 200b of the ring 180. The ring 234' and the rollers of the bearing 230 are then mounted on the shaft 182 by axial translation from the upstream end until they reach an axial stop against a cylindrical shoulder of the shaft 182. The rollers of this bearing 230 are then engaged in the flange 200a of the ring 180. Finally, the shaft 46 is mounted on the shaft 182 by axial translation from upstream, until it comes into axial contact with the inner ring of the bearing 130. The shafts 46, 182 being rotationally secured by sets of complementary splines 46'.The shafts 46, 182 are fixed to the actuator 62 to supply oil to its chambers.

[0077] The plain bearing P is supplied with oil directly by the channels 180b of the ring 180. It is understood that the thickness of the space is calculated so that controlled leaks occur at the interfaces between the channels 180b, 182b, so as to supply the plain bearing P. The oil then spreads over the entire axial extent of the plain bearing P and up to the rolling bearings 220, 230 for the purpose of lubricating them.

[0078] The radial thickness of the plain bearing is, for example, between 20 and 40µm.

[0079] The term "way" of device 174 refers to the connection between a channel 180b of the ring 180 and a channel 182b of the shaft 182. In the example shown, device 174 comprises three channels. Preferably, one of the channels is used for supplying oil to the actuator 62, and another is used for the oil return from the actuator 62. Finally, the last channel can be used for hydraulic protection of the actuator or for supplying oil to the gearbox 48.

[0080] In an alternative embodiment not shown, the device could be mounted downstream of the reducer. The shaft of the device would then be rotationally coupled to the planet carrier of the reducer, for example, in the case where the latter is rotatable.

[0081] Device 174 is configured for example to supply actuator 62 with an oil pressure between 2 and 200 bar, and preferably between 5 and 130 bar.

Claims

1. A fan module for an aircraft turbine engine, this module comprising a fan (12) which comprises a fan shaft (46) and variable pitch fan vanes (12a), and an oil transfer device (174) configured to ensure a transfer of oil between a stator and an actuator (62) that is secured in rotation to the fan shaft (46) and that is configured to control the pitch of the fan vanes, this device comprising: - a stator annulus (180) comprising a first cylindrical surface (180a), for example internal, and internal oil pipes (180b) which each open onto said first cylindrical surface (180a), and - a shaft (182) engaged in or on said annulus (180) and comprising a second cylindrical surface (182a) extending inside or around said first cylindrical surface (180a), the shaft comprising internal oil pipes (182b) which each open onto said second cylindrical surface (182a), characterised in that it further comprises: - a plain bearing (P) located between said first and second cylindrical surfaces (180a, 182a), and - rolling bearings (220, 230) mounted between the annulus (180) and the shaft (182), on either side of the plain bearing (P), each of these rolling bearings comprising rolling elements between two annular rolling tracks, in that one of the elements chosen from the annulus (180) and the shaft (182) carries rings (224, 234, 224', 234') defining first tracks of the rolling bearings, the second rolling tracks of these rolling bearings being integrated with the other of these elements, and in that the plain bearing (P) is formed by a single shrink ring (204) interposed between the first and second cylindrical surfaces (180a, 182a) and attached to one of said elements.

2. The module according to claim 1, wherein one of the elements carries the rings (224, 234) of the rolling bearings and the shrink ring (204).

3. The module according to claim 2, wherein the shrink ring has two cylindrical surfaces extending around each other, including a cylindrical shrink-fit surface and a cylindrical centering surface, this cylindrical centering surface having a diameter (D1) equal to the diameters of the second rolling tracks.

4. The module according to claim 2 or 3, wherein the annulus (180) carries the rings (224, 234) and the shrink ring (204).

5. The module according to claim 4, wherein the rings (224, 234) of the rolling bearings (220, 230) have identical internal diameters (D1).

6. The module according to claim 1, wherein one of the elements carries the rings (224', 234') and the other of the elements carries the shrink ring (204).

7. The module according claim 6, wherein the annulus (180) carries the shrink ring (204) and the shaft (182) carries the rings (224', 234').

8. The module according to claim 7, wherein the shrink ring (204) has two cylindrical surfaces extending around each other, including a cylindrical shrink-fit surface on the annulus (180) and a cylindrical centering surface on the shaft (182), the rings (224', 234') of the rolling bearings (220, 230) having internal diameters (D3', D4') different from each other and different from the diameter (D2) of the internal cylindrical surface of the shrink ring (204).

9. The module according to one of the preceding claims, wherein the shrink ring (204) comprises orifices (206) which are on the one hand located opposite the outlets of the pipes (180b, 182b) of one of the elements, and which are in fluidic communication with the pipes of the other of the elements by means of annular gorges (208, 210) formed at the level of the outlets of the pipes of this other element.

10. The module according to one of the preceding claims, wherein the fan (12) is driven in rotation by a reducer (48), said device being mounted upstream of the reducer and being configured to supply oil to the reducer and to the actuator, and possibly also to the reducer.

11. The module according to the preceding claim, wherein the fan (12) is driven by the fan shaft (46) which is guided by rolling bearings (54, 58) and which is coupled to the shaft (182) of the device (174).