TURBOMACHINE EQUIPPED WITH AN ELECTRIC MACHINE IN ITS LUBRICATION ENCLOSURE

Abstract

The invention relates to a turbomachine (1) for an aircraft, comprising: - a low-pressure shaft (2) extending along a longitudinal axis (X) to a rear end (3), - a turbomachine stator (4) supporting this rear end by a bearing (5) arranged in a first lubrication enclosure (7), and - an electric machine (15), located at the rear of the turbomachine, comprising a stator (24) fixed to the stator (4) and a rotor (25) driven in rotation by a connecting shaft (21) coupled in rotation to the low-pressure shaft, the connecting shaft extending the low-pressure shaft rearwardly. According to the invention, the electrical machine is contained in a second lubrication enclosure (19) separate from the first lubrication enclosure and the rotor (25) is connected to a coaxial drive shaft (37), disconnectably coupled to the connecting shaft (21) and supported by a rotation bearing (40) of the rotor (25). Figure for abstract: Fig. 2

Description

Title of the invention: TURBOMACHINE EQUIPPED WITH AN ELECTRIC MACHINE IN ITS LUBRICATION ENCLOSURE Technical field of the invention

[0001] The present invention relates to the field of turbomachines, and in particular aircraft. It relates in particular to a turbomachine equipped with an electric machine which is arranged at the rear of the turbomachine. Technological background

[0002] Faced with the environmental challenge in the aeronautical field and the increasing need for electrical power concomitantly with the number of equipment and new functions of the aircraft, the question of the hybridization of the turbomachine arises. The electric machine which equips the accessory boxes known by the English acronym AGB (for Accessory Gear Box) does not allow a significant gain in electrical power to be provided for all the functions of the aircraft and the efficiency of the conversion of mechanical power into electrical power is not at its optimum.

[0003] An electric machine is an electromechanical device based on electromagnetism allowing the conversion of electrical energy, for example, into mechanical energy (generator mode) or reversibly, allowing the production of electricity from mechanical energy (motor mode). The electric machine can also behave in generator mode as well as in motor mode.

[0004] The integration of the electric machine into various zones of the turbomachine proves to be complex and is constrained by the size, the temperature resistance of certain components of the electric machine, accessibility, the performance of the turbomachine itself, etc.

[0005] It is known to integrate an electric machine at the rear of a turbomachine where there is space for its integration and high temperature constraints and where layout difficulties apply. An example of an electric machine placed at the rear of the turbomachine is illustrated in [Fig.l].

[0006] In this example, the electric machine 01 comprises in this case a rotor 02 which is coupled in rotation with the low pressure shaft 03 which extends furthest to the rear of the turbomachine. However, the rotor 02 of the electric machine is not mounted directly on a rear end 04 of the low pressure shaft so as not to weigh down the low pressure shaft 03 and also due to an increasingly reduced size of the shafts of the turbomachine. The low pressure shaft 03 is guided by a rear rotation bearing 05 arranged at its rear end 04.

[0007] Decoupling of the rotor, or even of the entire electrical machine 01, may be necessary, for example, in the event of a fault. For this purpose, the electrical machine 01 is mounted independently of the rest of the turbomachine so as to facilitate its maintenance using a connection device 06. The connection device 06 is configured so as to connect or disconnect in rotation the rotor 02 of the electrical machine from the low-pressure shaft 03. The connection device 06 comprises a shaft section 07 fixed in a separable manner from the rear end 04 of the low-pressure shaft and carrying at least in part a rotation bearing 08 supporting at least in part the electrical machine. The rotation bearing 08 allows the rotation of the rotor of the electrical machine 01 independently of the rotation of the low-pressure shaft 03 when the latter is disconnected from the low-pressure shaft 03.The rotation bearing 08 is arranged in the lubrication enclosure 09 of the turbomachine, which is also crossed by the low pressure shaft, and is lubricated with grease because the latter does not require dynamic lubrication. This grease can allow the lubrication of the connection device itself, the rear end 04 of the low pressure shaft 03 and the shaft section 07 which are contained in the lubrication enclosure 09.

[0008] However, the rotation bearing 08 is subjected to a very high rotation speed when the connection device 06 is in the secured position, which can cause a risk of degradation of the grease and subsequently poor behavior of the rotation bearing 08. Furthermore, the low pressure shaft 03 is likely to expand transiently and this expansion causes the rotor 02 of the electrical machine 01 to move along the longitudinal axis and damage the seals closing the lubrication enclosure. The seals are sensitive to axial displacements.

[0009] There is a need to resolve all or part of the aforementioned drawbacks. Summary of the invention

[0010] The objective of the present invention is to provide a simple, economical and robust solution, which makes it possible to increase the service life and performance of the rotation bearing of the electric machine.

[0011] We achieve this objective in accordance with the invention by means of a turbomachine, in particular for aircraft, comprising: - a low pressure shaft extending along a longitudinal axis to a rear end, - a turbomachine stator supporting the rear end of the low pressure shaft by a rear bearing which is arranged in a first lubrication enclosure, and - an electric machine located at the rear of the turbomachine, and comprising an electric machine stator fixed to the stator of the turbomachine and an electric machine rotor capable of being driven in rotation by a connecting shaft which is coupled in rotation to the low pressure shaft, the connecting shaft extending the low pressure shaft rearwardly, the electric machine being contained in a second lubrication enclosure separate from the first lubrication enclosure and isolated from the first enclosure by a sealing element, and in that the electric machine rotor is connected to a drive shaft which is disconnectably coupled to the connecting shaft and which is coaxial with the connecting shaft, the drive shaft being supported by at least one rotation bearing of the electric machine rotor.

[0012] Thus, this solution makes it possible to achieve the aforementioned objective. In particular, this configuration makes it possible to isolate the electrical machine from the enclosure of the turbomachine and to be able to lubricate its components, in particular its rotation bearing independently of the components of the turbomachine and other than by grease. The service life and performance of the rotation bearing are improved. In addition, such a configuration requires very few structural modifications to the turbomachine.

[0013] The turbomachine also comprises one or more of the following features and / or steps, taken alone or in combination:

[0014] - the second enclosure is supplied with lubricant by a feed pump which is rotated by means of the low pressure shaft or the electric machine rotor.

[0015] - the turbomachine comprises a device for disconnecting the machine rotor electrical connection of the connecting shaft, the disconnection device comprising a carriage cooperating with the drive shaft and movable along the longitudinal axis relative to the drive shaft, the carriage being provided with first dog teeth intended to engage or disengage with second dog teeth carried by an external crown connected to the feed pump.

[0016] - the turbomachine comprises a carriage device comprising a section shaft fixed to the connecting shaft and a sleeve connecting the shaft section to the rear end of the low pressure shaft in a removable manner, the sleeve being secured in rotation to the rear end by first coupling means and to the shaft section by second coupling means, the sleeve being axially movable relative to the shaft section via the second coupling means, at least the first coupling means being arranged in the first lubrication enclosure.

[0017] - the first coupling means comprise internal axial grooves which are provided on a radially inner surface of the sleeve and complementary external axial grooves which are located on a radially outer surface of the rear end of the low pressure shaft.

[0018] - the second coupling means comprise axial grooves external grooves which are provided on a radially internal surface of the sleeve and complementary internal axial grooves which are located on a radially external surface of the shaft section, the external axial grooves and the complementary internal axial grooves being sliding.

[0019] - the sleeve is axially immobilized on the rear end at least by a nut tightening.

[0020] - a labyrinth seal intended to isolate the first enclosure is formed between the shaft section and a cylindrical bearing surface of the turbomachine stator.

[0021] - the turbomachine comprises a sealed closure member for the first enclosure lubrication, the closing member comprising a cylindrical body mounted with sealing inside the rear end and a collar fixed to the shaft section mounted with sealing on the shaft section, the closing member comprising a housing formed between the annular sole and the cylindrical body housing a portion of the rear end and of the tightening nut which is arranged radially around the rear end and downstream of the sleeve.

[0022] - the turbomachine comprises a sealing member at least partly of the first lubrication enclosure, the closing member being fixed on the rear end by means of the tightening nut and comprising a cylindrical body mounted with sealing inside the rear end and a wall closing the rear end of the low pressure shaft.

[0023] - the shaft section comprises a separating wall which extends radially towards the longitudinal axis and downstream of the closing member so as to at least partially close the first lubrication enclosure, a cavity being formed between the wall, the shaft section and the separating wall.

[0024] - a sealing element is arranged radially between the clamping nut and the section of tree.

[0025] - the second coupling means are arranged in an intermediate cavity formed between the first enclosure and the second enclosure.

[0026] - the second coupling means comprise ball splines.

[0027] - the turbomachine comprises an annular shell centered on the longitudinal axis, the annular shell comprising a base wall crossed by the rear end and bearing against an internal ring of the rear bearing, and a cylindrical section extending along the longitudinal axis, a labyrinth seal intended to isolate the first enclosure being formed between the cylindrical section and a cylindrical bearing surface of the stator of the turbomachine.

[0028] - - the sealing element insulating the first enclosure is a non-sealing gasket pressurized.

[0029] - - the turbomachine comprises an actuator capable of controlling the movement of the connection device.

[0030] - - the carriage device is arranged in an enclosure or cavity separate from the second enclosure dedicated to the electric machine.

[0031] The invention relates to an aircraft comprising at least one turbomachine having any one of the aforementioned characteristics. Brief description of the figures

[0032] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly on reading the detailed explanatory description which follows, of embodiments of the invention given as purely illustrative and non-limiting examples, with reference to the appended schematic drawings in which:

[0033] - [Fig.l] represents an example of an electrical machine installed at the rear of a turbomachine according to the prior art;

[0034] - [Fig.2] is a schematic and partial axial sectional view of an example of turbomachine to which the invention applies;

[0035] - [Fig.3] is an axial sectional view of a part of a carriage device of the turbomachine according to a first embodiment;

[0036] - [Fig.4] represents a detailed view of a connection device between a rear end of a low pressure shaft and a rotor shaft of an electric machine according to the invention;

[0037] - [Fig.5] is a perspective view of a plug intended to be mounted on the shaft low pressure of the turbomachine according to one embodiment of the invention;

[0038] - [Fig.6] is a perspective and axial sectional view of the plug according to [Fig.5]

[0039] - [Fig.7] is an axial sectional view of another embodiment of a device for turning the turbomachine according to the invention; and

[0040] - [Fig.8] is an axial sectional view of another embodiment of a device for turning the turbomachine according to the invention. Detailed description of the invention

[0041] [Fig.l] has been described previously.

[0042] [Fig. 2] schematically and partially represents a turbomachine 1 with longitudinal axis X to which the invention applies. The turbomachine 1 is intended to be mounted on an aircraft. In particular, the turbomachine may be a turbojet, a turboprop, a turboshaft or generally a turbomachine which includes a fan or a propeller which is either ducted or unducted. Only the rearmost or downstream part of the turbomachine along the longitudinal axis X is shown.

[0043] In the present invention, and generally, the terms "upstream" and "downstream" are defined with respect to the circulation of gases or air flows in the turbomachine and here along the longitudinal axis X. The terms "axial" and "axially" are defined with respect to the longitudinal axis X. The terms "external", "external", "internal", "internal" and "radial" are defined with respect to a radial axis Z which extends from the longitudinal axis X and with respect to the distance from the longitudinal axis X. The radial axis Z is perpendicular to the longitudinal axis X.

[0044] The turbomachine 1 comprises a low-pressure shaft 2 which extends along the longitudinal axis X and up to a rear end 3. Advantageously, the low-pressure shaft 2 is coupled to a rotor of a turbine (not shown) of the turbomachine. In particular, the turbine considered, but not limited to, is the low-pressure turbine. The rotor of the low-pressure turbine is generally connected via the low-pressure shaft 2 to a rotor of a low-pressure compressor (not shown) which is located further upstream in the turbomachine along the longitudinal axis X.

[0045] The low pressure shaft 2 is supported by a stator 4 of the turbomachine using several bearings. More specifically, the turbomachine comprises a rear bearing 5 allowing the stator 4 to support the rear end of the low pressure shaft 2. Optionally, the rear bearing 5 comprises an inner ring 5a secured to the rear end 5 of the low pressure shaft 2 and an outer ring 5b secured to a cylindrical bearing surface 6a of the stator 4 of the turbomachine. The cylindrical bearing surface 6a is for example secured to a bearing support 6. Rolling members 5c, for example rollers, are arranged between the inner and outer rings 5a, 5b.

[0046] Advantageously, the rear bearing 5 is arranged in a first lubrication enclosure 7. This first lubrication enclosure 7 is closed by means of seals 8. In particular, a first seal 8a is arranged between a first shell 9 of the stator 4 and a cylindrical wall surface 10 of the low-pressure shaft 2 and a second seal 8b is placed between a second shell 11 connected to the stator 4 and a shaft section 12 which will be described later. Advantageously, but not limitingly, the first shell 9 and the second shell 11 are integral with the bearing support 6. In other words, the first lubrication enclosure 7 is delimited by the rear end 3 of the low-pressure shaft, the first shell 9 and the second shell 11 of the stator 4 as well as the first and second seals 8a, 8b.

[0047] Advantageously, the first enclosure 7 is supplied by a lubrication circuit which is supplied by a power source (not shown). The lubrication circuit comprises for example a nozzle 13 which is shown schematically in [Fig. 2]. The nozzle 13 in this example targets the rear bearing 5. This can be connected to a conduit which passes through a radial arm 14a of an exhaust casing 14. The lubricant is preferably oil (in the form of a mist) which makes it possible to lubricate and cool the bearings which produce heat.

[0048] The turbomachine 1 comprises an electrical machine 15 which is located at the rear of the turbomachine. The electrical machine 15 is advantageously housed in a cavity 16 which is formed downstream of the rear end 3 of the low-pressure shaft. In other words, the electrical machine 15 is arranged downstream of the rear end 3 of the low-pressure shaft. The cavity 16 is closed at least in part by a cover 17 which is fixed to the stator 4, and in particular to the exhaust casing 14 of the turbomachine, by a bolted connection for example. A thermal protection 18 can be applied to the internal wall of the cover 17 to protect the latter from the heat produced by the exhaust gases at the outlet of the low-pressure turbine (not shown) of the turbomachine.

[0049] The electrical machine 15 is arranged more precisely in a second lubrication enclosure 19 which is dedicated for the electrical machine 15 and which is distinct and isolated at least in part from the first lubrication enclosure 7. Preferably, the second lubrication enclosure 19 is distinct from the first lubrication enclosure 7. The second enclosure 19 is contained in the cavity 16.

[0050] The second enclosure 19 is delimited, advantageously, but not limitingly, at least in part by a stator armature 20, a connecting shaft (described later) 21 and a casing 22. The casing 22 is advantageously, but not limitingly, fixed to the stator armature by means of fixing members (not shown).

[0051] The electric machine 15 comprises a stator 24 and a rotor 25. The electric machine 15 can alternately operate in generator mode and in motor mode. That is to say, the electric machine 15 can take power from the low pressure shaft or inject power onto the low pressure shaft.

[0052] Advantageously, but not limited to, the electric machine stator 24 comprises electric bearings and the electric machine rotor 25 comprises permanent magnets. In the present example, the electric machine stator 24 surrounds the electric machine rotor 25 and is fixed to the stator 4 of the turbomachine.

[0053] Advantageously, the electric machine stator 24 comprises the stator armature 20 which comprises for example a first arm 20a and a second arm 20b which are located on either side of the electric machine stator 24 along the longitudinal axis X. The electric machine 15 may comprise a housing (not shown) which radially surrounds the electric machine stator 24 and the electric machine rotor 25. The first arm 20a and the second arm 20b may be fixed upstream and downstream of the housing. The first and second arms 20a, 20b extend radially towards the longitudinal axis X. The rotor and the electric machine stator are contained axially between the first and second arms 20a, 20b and optionally radially in the housing.

[0054] A first flange 27 advantageously, but not limited to, fixing the electric machine stator 24 (in particular the stator armature 20) to a second flange 28 of the stator 4 (in particular the exhaust casing 14). The first flange 27 advantageously, but not limited to, extending from the stator armature 20 and radially outwards. The second flange 28 is here carried by one of the first and second shells 9, 11 of the stator 4 of the turbomachine 1 and extends radially outwards. This makes it possible to free up space in the enclosures of the turbomachine. The fixing of the first and second flanges 27, 28 is carried out for example by a bolt-type fixing member 29. Other similar fixing members 29 allowing easy detachment of the first and second flanges 27, 28 are conceivable. Advantageously, the fixing member 29 comprises a threaded rod whose axis extends parallel to the longitudinal axis X.The fixation here is axial.

[0055] The rotor 25 of the electric machine 15 is advantageously driven by the low pressure shaft 2 in a disconnectable manner. This is made possible by a connection device 30 which is configured so as to rotationally couple or uncouple the rotor 25 of the electric machine 15 from the low pressure shaft 2. Uncoupling can occur in the event of damage to the electric machine 15 which would require the rotor 25 of the electric machine 15 to no longer be driven by the low pressure shaft.

[0056] For this purpose, the turbomachine 1 comprises a connecting shaft 21 which extends along the longitudinal axis X. The connecting shaft 21 extends downstream of the rear end 3 of the low pressure shaft 2 and extends the low pressure shaft towards the rear of the turbomachine 1. The connecting shaft 21 is arranged coaxially with the low pressure shaft 2. The connecting shaft 21 is hollow and is closed at a downstream end 21b for example by a plug 23. The connecting shaft 21 is connected to the rear end 3 of the low pressure shaft 2 by the shaft section 12 of a carriage device detailed later in this description. Advantageously, but not limitingly, the shaft section 12 is secured to the connecting shaft 21 by a fixing member 33 (shown in [Fig. 3]).

[0057] With reference to FIG. 3, the connecting shaft 21 comprises a third fixing flange 31 which is fixed to a fourth fixing flange 32 of the shaft section 12. The third fixing flange 31 extends radially from an upstream end 21a of the connecting shaft 21. The upstream end 21a is, in other words, opposite the downstream end 21b of the connecting shaft 21 along the longitudinal axis X. The fixing is carried out here by the bolt-type fixing member 33 so as to easily separate or secure the connecting shaft 21 from the shaft section 12. Other similar fixing members 33 can be used to carry out this fixing. The axis of the threaded rod of this bolted connection is here axial. In this way, it is possible to extract the electric machine 15 by removing the fixing members 29 and 33 at the respective flanges to carry out maintenance thereof. The turbomachine 1 can continue to operate without the electric machine 15.

[0058] The stator armature 20 of the electrical machine 15 comprises a cylindrical bearing surface 34 coaxial with an axial portion 35 of the connecting shaft 21. A seal 36 is for example arranged between the cylindrical bearing surface 34 and the axial portion 35 to isolate, at least in part, the second enclosure 19 from the first enclosure 7. This seal 36 is for example close to a carriage device which is described later. The plug 23 also makes it possible to isolate and seal the second enclosure 19 from the first enclosure 7. We can consider that the second enclosure 19 is blind. Advantageously, the seal 36 is a labyrinth seal. The latter comprises portions carried by the cylindrical bearing surface 34 and by the axial portion 35. Such an arrangement makes it easier to separate the electrical machine 15. Furthermore, this seal is not pressurized.The air flow which makes it possible to pressurize the cavity 16 does not circulate in the second enclosure 19.

[0059] Still in [Fig.3], the electric machine 15 comprises a drive shaft 37 which is on the one hand integral in rotation with the rotor 25 of the electric machine 15 and on the other hand with the connecting shaft 21. Optionally, the drive shaft 37 is centered and coaxial with the connecting shaft 21. At least one annular ferrule 38 extending radially makes it possible to connect the drive shaft 37 to the electric machine rotor 25. The drive shaft 37 is supported by at least one rotation bearing 40.

[0060] In the present embodiment there are two rotation bearings. Each rotation bearing 40 comprises an inner ring 40a secured to the drive shaft 37 and an outer ring 40b secured to a bearing support 39 secured to the stator armature 20. Rolling members 40c are arranged between the inner and outer rings 40a, 40b. Advantageously, but not limitingly, the rolling members are balls. In other words, the electrical machine 15 is on its own rotation bearings.

[0061] The turbomachine optionally comprises a toothed annular ferrule 42 which is secured in rotation to the connecting shaft 21 (preferably by means of tight splines) and which transmits the rotational movement of the low pressure shaft 2 to the drive shaft 37 of the electrical machine 15. In this example, the annular ferrule 42 is centered on the longitudinal axis X. A nut 47 makes it possible to couple the annular ferrule 42 to the connecting shaft 21. The annular ferrule 42 has a diameter greater than that of the connecting shaft 21 so as to facilitate the integration of the connection device 30. The connecting shaft 21 could include this greater diameter so as to dispense with the annular ferrule 42.

[0062] The toothed annular ferrule 42 also makes it possible to drive a lubricant supply pump 43 for the electrical machine 15. For this purpose, an external crown 44, centered on the longitudinal axis X, is mounted so as to be integral in rotation with the annular ferrule 42. Coupling means such as splines allow the external crown 44 and the annular ferrule 42 to be secured.

[0063] Advantageously, but not limitatively, the external crown 44 is driven in rotation relative to the casing 22 or a portion of the casing by means of rotational guide means, here for example a double bearing 48 as can be seen in FIGS. 2 and 4. The double bearing 48 makes it possible to control the position of the external crown 44 and better operation of the disconnection device 30. Preferably, the double bearing 48 comprises balls which make it possible to obtain very little axial play.

[0064] Advantageously, but not limitatively, the external crown 44 comprises at a downstream end 44b an annular row of external teeth 45 which mesh with a pinion 46 for actuating the feed pump 43. The latter is connected to a lubricant supply source such as a reservoir. Advantageously, the lubricant is oil which makes it possible to lubricate the second enclosure 19 containing the electrical machine 15 and the rotation bearings 40.

[0065] Another seal (not shown), which makes it possible to isolate the second enclosure, is mounted radially between the casing 22 and the connecting shaft 21, preferably towards the downstream end of the annular shell 42. The seal could be mounted directly between the connecting shaft and the casing 22. Advantageously, this seal is not pressurized by the air circulating in the cavity 16.

[0066] The casing 22 encloses the feed pump 43 and receives the downstream end 21b of the connecting shaft 21. The feed pump 43 could comprise its own independent casing fixed to the casing 22 or its casing could be directly integrated into the casing 22. Advantageously, the casing of the pump would be only a part of the casing 22, the other part of the casing 22 serving in particular to close the enclosure and to ensure, for example, the support of the sealing joint.

[0067] The disconnection device 30 comprises first dog teeth 53, connected to the drive shaft 37, which are intended to mesh with second dog teeth 54 connected to the connecting shaft 21. The connection device comprises for example a carriage 50 mounted axially movable relative to the drive shaft 37 between a coupling position and an uncoupling position. In the present exemplary embodiment, the carriage 50 comprises external splines 51 which extend along the longitudinal axis. These external splines 51 are intended to engage with internal splines 52 which are carried by the drive shaft 37. The internal splines 52 also extend along the longitudinal axis X.

[0068] The carriage 50 further comprises the first dog teeth 53 which extend axially while the second dog teeth 54 are carried by a member secured to the connecting shaft 21. In the present example, the member is the external ring gear 44. The second dog teeth 54 are positioned for example at an upstream end 44a of the external ring gear 44 and in the form of an annular row.

[0069] In this way, the low pressure shaft 2 drives the rotor 25 of the electric machine 15 in rotation via the connecting shaft 21, the annular ferrule 42, the external crown 44, and the dog teeth 53, 54 which are engaged in each other in the coupling position of the carriage 50. The first and second dog teeth 53, 54 engaged in each other in the coupling position are shown in [Fig. 4]. Thanks to this configuration, the low pressure shaft 2 also makes it possible to drive the feed pump 43 of the electric machine 15 in rotation, via the toothed annular ferrule 42, the external crown 44 and the pump actuating pinion 46.

[0070] In the event that it is necessary to uncouple the rotor 25 of the electric machine 15 and the low-pressure shaft, the first dog teeth 53 disengage from the second dog teeth 54. For this purpose, the carriage 50 is controlled so as to slide towards the uncoupling position (upstream) to disengage the first dog teeth 53 from the second dog teeth 54. In this position, the rotor 25 of the electric machine 15 is no longer driven by the low-pressure shaft 2. In this case, the low-pressure shaft 2 continues to drive the feed pump 43 and the rotor 25 of the electric machine 15 is free to rotate.

[0071] Advantageously, but not limitatively, the carriage 50 is controlled by an actuator 55. The actuator 55 may be a jack which comprises a housing which is carried by the casing 22 or by the stator armature 20, or by both the casing and the stator armature, and a rod sliding inside the housing.

[0072] According to a first exemplary embodiment illustrated in [Fig. 3], the turbomachine comprises a carriage device 60 which makes it possible to take into account the thermal expansions of different components of the turbomachine. In particular, the shafts of the turbomachine, in particular the low pressure shaft 2 which is swept by the gases from the combustion chamber, can elongate relative to the stator of the turbomachine and transiently. Typically, the stators of the turbomachine will be exposed first to the highest temperatures which will cause their thermal expansion or their elongation, then the rotors which are exposed to the lower temperatures than those seen by the stators will expand in a second time. The shafts do not move or elongate in the same way as the stators.

[0073] In this exemplary embodiment, the carriage device 60 is arranged in the first enclosure 7 (different from the second enclosure) which avoids the transmission of the movement of the low pressure shaft to the second dedicated enclosure 19 of the electrical machine 15.

[0074] The carriage device 60 comprises the shaft section 12 which extends along the longitudinal axis X. The shaft section 12 is removably attached to the rear end 3 of the low pressure shaft 2. The shaft section 12 is coaxial with the low pressure shaft 2 and rotates around the longitudinal axis X. In the example of [Fig. 3], the shaft section 12 is arranged radially at least partly around the rear end 3 of the low pressure shaft 2 and is located at least partly in the first lubrication enclosure 7. We understand that the shaft section 12 is hollow.

[0075] The carriage device 60 comprises a sleeve 61 connecting the shaft section 12 to the rear end 3 of the low pressure shaft 2. The sleeve 61 extends along the longitudinal axis X and is concentric with the rear end 3 of the low pressure shaft 2. The sleeve 61 is advantageously hollow. As illustrated in [Fig. 3], the sleeve 61 is rotationally fixed to the low pressure shaft 2 by first coupling means 62. The latter comprise internal axial splines 63 and complementary external axial splines 64. The internal axial grooves 63 are in this example formed on a radially internal surface 65 of the sleeve 51 and extend radially towards the longitudinal axis X. Conversely, the complementary external axial grooves 64 are located on a radially external surface 66 of the rear end 3 of the low pressure shaft 2 and extend radially outwards.

[0076] Advantageously, the sleeve 61 is immobilized axially on the rear end 3 of the low pressure shaft 2 at least by a clamping nut 67. In the present example, the clamping nut 67 is arranged downstream of the complementary external axial grooves 64 of the rear end 3 of the low pressure shaft 2. The sleeve 61 is also immobilized axially by the internal ring 5b of the rear bearing 5. Optionally, the sleeve 61 is located downstream of the rear bearing 5. In other words, the sleeve 61 is arranged and axially locked between the internal ring 5b and the tightening nut 67. In this way, the first coupling means 62 only allow the rotational movement of the low pressure shaft 2 to be transmitted to the connecting shaft 21. We also understand that the sleeve 61 is arranged in the first lubrication enclosure 7.

[0077] According to another advantageous characteristic, the sleeve 61 is integral in rotation with the shaft section 12 by second coupling means 68. The latter comprise external axial splines 69 and complementary internal axial splines 70. The external axial splines 69 are in this example formed on a radially external surface 71 of the sleeve 61 and extend radially outwards. The complementary internal axial splines 70 are located on a radially internal surface 72 of the shaft section 12. The splines of the low pressure shaft 2, of the sleeve 61 and of the shaft section 12 engage with each other respectively so as to transmit the rotational movement of the pressure shaft 2 to the connecting shaft 21 which is fixed to the shaft section 12. The sleeve 61 comprises the internal axial splines and external axial splines.

[0078] Advantageously, the shaft section 12 can be axially movable relative to the sleeve 61 secured to the rear end 3 via the second coupling means 68. In this way, unlike the splines of the first coupling means 62 which are axially blocked (static), the splines of the second coupling means 68 are sliding. This configuration promotes axial movements of the pressure shaft 2 and prevents axial movements of the low-pressure shaft 2 due to thermal expansion from being transmitted towards the rear where the electrical machine 15 is located; the electrical machine 15 is not impacted by these movements.In other words, the connecting shaft 21 is axially fixed (relative to the casing 22 thanks to the double bearings 48) (the shaft section 12 is secured to the connecting shaft 21 by the fixing member 33), and the movement of the low-pressure shaft 2 is contained in the first enclosure 7 and is not transmitted to the rotor of the electrical machine 15, nor even to the non-pressurized seals which are placed in the second enclosure 19 (and on either side axially of the connection device 30). This makes it possible to increase the service life of the seals.

[0079] In [Fig. 3], the splines 69, 70 need to be lubricated since they are sliding. A scoop 74 is arranged opposite a lubricant ejection means which may be the nozzle 13. Advantageously, but not limitingly, the scoop 74 opens onto the low pressure shaft 2 and upstream of the rear bearing 5. The lubrication path is represented schematically by the arrows L through grooves which are formed in the radially external surface 66 of the rear end 3 of the low pressure shaft 22. The lubricant also passes through the first means coupling means 62 and then continues towards the second coupling means 68 (i.e. the sliding grooves 69, 70) to open into the first enclosure 7, upstream of the seal 8b. The lubricant also circulates around the tightening nut 67.

[0080] Advantageously, but not limitingly, the seal 8b is a labyrinth seal formed between the shaft section 12 and a cylindrical bearing surface 11b of the stator 4 of the turbomachine 2. The shaft section 12 has a radially external surface 73 from which first blades 8ba extend radially. Second blades 8aa extend radially towards the longitudinal axis X from a radially internal surface of the cylindrical bearing surface 11b secured to the second shell 11. In other words, a part of the labyrinth seal is carried by the shaft section 12 and the other part of the labyrinth seal is carried by the cylindrical bearing surface 11b of the second shell 11 of the stator 4.

[0081] With reference to Figures 3, 5 and 6, the turbomachine 1 comprises a closing member 75 configured so as to seal the first lubrication enclosure 7 and to prevent the fluid from flowing towards the second enclosure 19, for example at the level of the tightening nut 67. The closing member 75 comprises a cylindrical body 76 mounted with sealing inside the rear end 3 and an annular collar 77 mounted with sealing on the shaft section 12. The collar 77 is fixed here, for example, on the shaft section 12. The cylindrical body 76 is open at each of its first and second ends 76a, 76b between which it extends. The cylindrical body 76 comprises two annular grooves 78 which open onto an external wall 79 of the cylindrical body 76 and which each receive an annular seal 80. In other words, the grooves 78 are centered on the axis A of the cylindrical body 76.These annular seals 80 come into contact with a radially internal surface 81 of the rear end 3 of the low pressure shaft 2 so as to ensure sealing in this area. Of course, a single groove with a single seal could be provided to ensure the desired sealing. These seals 80 will move axially because the rear end 3 of the low pressure shaft 2 moves axially relative to the cylindrical body 76, the annular collar 77 being fixed on the shaft section 12.

[0082] Advantageously, the closing member 75 comprises an annular sole 82 which extends radially from one end of the cylindrical body 76. The annular sole 82 comprises at its free end the collar 77 which extends parallel to the axis A of the cylindrical body 76. The collar 77 is located at a distance from the cylindrical body 76, forming a housing 83. The distance corresponds to the height of the annular sole 82. The housing 83 formed between the collar 77 and the cylindrical body 76 is intended to house at least in part the tightening nut 67 and a part of the rear end 3 of the low pressure shaft 2. The clamping nut 67 is arranged radially around the rear end 3 and downstream of the sleeve 61.

[0083] The collar 77 comprises two grooves 84 opening onto a radially external surface 85 of the collar 77 and each receiving a seal 86 which is annular. Advantageously, the grooves 84 are centered on the axis A of the cylindrical body 76. The seals 86 come into contact with a radially internal surface 87 of the shaft section 12. The free end 88 of the collar 77 comprises a first bearing surface 89 coming into contact with a second bearing surface formed by a shoulder 90 of the shaft section 12. The shoulder 90 optionally extends radially towards the longitudinal axis. A circlip 91 is advantageously, but not limited to, mounted on the shaft section 12 and downstream of the closure member 75 in order to prevent any axial displacement of the latter. The circlip 91 bears against a portion of the surface of the annular sole 82. This completes and ensures the seal in this area.The circulation of the lubricant towards the inside of the rear end 3 which is hollow is hindered by the seals 80 and also towards the inside of the shaft section which is also hollow. In addition, the closing member 75 (as well as the circlip 91) prevents the rotation and movement of the clamping nut 67 along the longitudinal axis. Alternatively, the anti-rotation and axial movement function of the clamping nut 67 could be achieved by a system of anti-rotation washer and circlip.

[0084] [Fig. 7] shows another embodiment of the closing member 75 intended to at least partially close the first enclosure 7 in a sealed manner. This embodiment differs in that the closing member 75 is fixed to the rear end 3 and comprises a wall 92 which closes the rear end 3. In particular, the wall 92 closes the opening located at the second end 76b of the cylindrical body 76 which is inserted inside the rear end 3 of the low pressure shaft 2. The wall 92 is solid in other words. This comprises a downstream surface 93 which advantageously, but not limitatively, extends in a plane perpendicular to the longitudinal axis X. The closing member 75 also differs in that it is devoid of the collar. The closing member 75 comprises the annular sole 82 which is secured to the rear end 3 using the clamping nut 67.In this case, the closing member 75 will move axially at the same time as the rear end 3 of the low pressure shaft 2. The seals 80 are then immobile and remain in contact with the radially internal surface 81 of the rear end 3. The lubricant will lubricate the sliding grooves of the second coupling means 68 but does not circulate towards the inside of the rear end 3 of the low pressure shaft 2.

[0085] In the context of this embodiment of [Fig.7], the carriage device 60 is arranged in the first enclosure 7. The shaft section 12 optionally comprises a separation wall 100 which extends radially towards the longitudinal axis X and downstream of the closing member 75. Advantageously, but not limitingly, the separation wall 100 extends the fourth fixing flange 32 of the shaft section 12. The separation wall 100 is for example plain. The separation wall 100 makes it possible to at least partially close the first lubrication enclosure 7. A cavity 101 is formed between the wall 92 of the closing member 75, the separation wall 100 of the shaft section and the shaft section 12 itself. Lubricant can access the cavity 101 by circulating outside the tightening nut 67.

[0086] Optionally, an annular sealing element 103 is arranged radially between the clamping nut 67 and the shaft section 12 to prevent the cavity 101 from filling with lubricant and forming an oil retention. Advantageously, but not limitingly, the sealing element 103 is a lip seal. In particular, the lip seal comprises a base 104 and a lip 105 which rises from the base 104. The base 104 is embedded in a groove formed in the radially internal surface 87 of the shaft section 12 while the lip 105 is intended to come into contact with an external surface of the tightening nut 67. The sealing element 103 is advantageously arranged upstream of the plane containing the downstream surface of the wall 92. In this configuration, there is no longer any sealing element which works in axial displacement as was the case with the sealing joints 80.

[0087] [Fig. 8] represents yet another embodiment of sealing means of the first lubrication enclosure 7. In this embodiment, the sleeve 61 is fixed on the rear end 3 and the first coupling means 62 are formed between the sleeve 61 and the rear end 3. The first coupling means 62 are always static and arranged in the first lubrication enclosure 7. On the other hand, the second coupling means 68 which secure in rotation the sleeve 61 of the shaft section 12, are arranged in an intermediate cavity 106 formed between the first enclosure 7 and the second enclosure 19. In this way, the carriage device 60 is arranged in the intermediate cavity 106 which is different from the second enclosure dedicated to the electrical machine. The first sealing enclosure 7 is here closed at least in part using an annular ferrule 107 which carries a portion of the labyrinth seal 8b.The annular ferrule 107 comprises a base wall 108 which bears against the outer ring 5b of the rear bearing 5. The base wall 108 has an annular surface which is defined in a plane perpendicular to the longitudinal axis X. The annular base wall 108 is crossed by the rear end 3 of the low pressure shaft 2 which passes through its opening. The . circulation of the lubricant is hindered by the base wall 108 immediately downstream of the inner ring 5b of the rear bearing 5.

[0088] The annular ferrule 107 comprises a cylindrical section 109, connected to the base wall 108, from which the first blades 8ba extend. The cylindrical section 109 extends along the longitudinal axis X and radially around the sleeve 61. The latter also advantageously extends upstream of the second coupling means 68. Advantageously, but not limitingly, the annular ferrule 107 has an L-shaped annular section with the base wall 108 and the cylindrical section 109.

[0089] The second coupling means 68 are arranged downstream of the seal 8b. Advantageously, the second coupling means 68 comprise ball splines 110. The ball splines 110 promote the transmission of the rotational movement of the low-pressure shaft 2 to the connecting shaft 21 which is fixed to the shaft section 12 and connected to the rotor 25 of the electrical machine 15. The ball splines 110 also allow the axial displacement of the rear end 3 of the low-pressure shaft 2 relative to the shaft section 12. Advantageously, the ball splines 110 are lubricated using grease. In this way, it is not necessary for the ball splines 110 to be isolated in the first enclosure 7 into which lubricant is continuously supplied. In other words, there is no oil circulating in the intermediate cavity 106.

Claims

Claims

1. A turbomachine (1), in particular for an aircraft, comprising: - a low-pressure shaft (2) extending along a longitudinal axis (X) to a rear end (3), - a turbomachine stator (4) supporting the rear end (3) of the low-pressure shaft (2) by a rear bearing (5) which is arranged in a first lubrication enclosure (7), and - an electric machine (15) located at the rear of the turbomachine, and comprising an electric machine stator (24) fixed to the stator (4) of the turbomachine and an electric machine rotor (25) capable of being driven in rotation by a connecting shaft (21) which is coupled in rotation to the low-pressure shaft (2), the connecting shaft (21) extending the low-pressure shaft (1) rearwardly,characterized in that the electric machine (15) is contained in a second lubrication enclosure (19) separate from the first lubrication enclosure (7) and is isolated from the first enclosure by a sealing element (36), and in that the electric machine rotor (25) is connected to a drive shaft (37) which is detachably coupled to the connecting shaft (21) and which is coaxial with the connecting shaft (21), the drive shaft (37) being supported by at least one rotation bearing (40) of the electric machine rotor (25).,

2. Turbomachine (1) according to claim 1, characterized in that the second enclosure (19) is supplied with lubricant by a supply pump (43) which is driven in rotation via the low pressure shaft (2) or the electric machine rotor (25).

3. Turbomachine (1) according to one of claims 1 and 2, characterized in that it comprises a disconnection device (30) for the electric machine rotor (25) from the connecting shaft (21), the disconnection device (30) comprising a carriage (50) cooperating with the drive shaft (37) and movable along the longitudinal axis (X) relative to the drive shaft (37), the carriage (50) being provided with first dog teeth (53) intended to engage or disengage with second dog teeth (54) carried by an external crown (44) connected to the feed pump (43).

4. Turbomachine (1) according to one of claims 1 to 3, characterized in that it comprises a carriage device (60) comprising a shaft section (12) fixed to the connecting shaft (21) and a sleeve (61) connecting the shaft section (12) to the rear end (3) of the low pressure shaft in a removable manner, the sleeve (61) being secured in rotation to the rear end (3) by first coupling means (62) and to the shaft section (12) by second coupling means (68), the sleeve (61) being axially movable relative to the shaft section (12) via the second coupling means (68), at least the first coupling means (62) being arranged in the first lubrication enclosure (7).

5. Turbomachine (1) according to claim 4, characterized in that the first coupling means (62) comprise internal axial grooves (63) which are provided on a radially internal surface (65) of the sleeve (61) and complementary external axial grooves (64) which are located on a radially external surface (66) of the rear end (3) of the low pressure shaft (2).

6. Turbomachine (1) according to one of claims 4 and 5, characterized in that the second coupling means (68) comprise external axial splines (69) which are provided on a radially internal surface of the sleeve (61) and complementary internal axial splines (70) which are located on a radially external surface of the shaft section (12), the external axial splines (69) and the complementary internal axial splines (70) being sliding.

7. Turbomachine (1) according to one of claims 4 to 6, characterized in that the sleeve (61) is immobilized axially on the rear end (3) at least by a clamping nut (67).

8. Turbomachine (1) according to one of claims 4 to 7, characterized in that a labyrinth seal (8b) intended to isolate the first enclosure (7) is formed between the shaft section (12) and a cylindrical bearing surface (11b) of the stator (4) of the turbomachine.

9. Turbomachine (1) according to claim 7 when it depends on claim 4 or claim 8 when it depends on claims 4 and 7, characterized in that it comprises a sealing closure member (75) of the first lubrication enclosure (7), the closure member (75) comprising a cylindrical body (76) mounted with sealing inside the rear end (3) and a collar (77) fixed to the shaft section (12) mounted with sealing on the shaft section (12), the closing member (75) comprising a housing (83) formed between the annular sole (77) and the cylindrical body (76) housing a portion of the rear end (3) and of the tightening nut (67) which is arranged radially around the rear end (3) and downstream of the sleeve (61).

10. Turbomachine (1) according to claim 7 or according to claim 8 when it depends on claim 7, characterized in that it comprises a closure member (75) sealing at least in part the first lubrication enclosure (7), the closure member (75) being fixed on the rear end (3) by means of the tightening nut (67) and comprising a cylindrical body (76) mounted with sealing inside the rear end (3) and a wall (92) closing the rear end (3) of the low pressure shaft (2).

11. Turbomachine (1) according to the preceding claim, characterized in that the shaft section (12) comprises a separating wall (100) which extends radially towards the longitudinal axis (X) and downstream of the closing member (75) so as to at least partially close the first lubrication enclosure (7), a cavity (101) being formed between the wall (92), the shaft section (12) and the separating wall (100).

12. Turbomachine (1) according to one of claims 10 to 11, characterized in that a sealing element (103) is arranged radially between the clamping nut (67) and the shaft section (12).

13. Turbomachine (1) according to one of claims 4 to 7, characterized in that the second coupling means (68) are arranged in an intermediate cavity (106) formed between the first enclosure (7) and the second enclosure (19).

14. Turbomachine (1) according to the preceding claim, characterized in that the second coupling means (68) comprise ball splines (110).

15. Turbomachine (1) according to one of claims 13 and 14, characterized in that it comprises an annular shroud (107) centered on the longitudinal axis (X), the annular shroud (107) comprising a base wall (108) crossed by the rear end (3) and bearing against an internal ring (5b) of the rear bearing (5), and a cylindrical section (109) extending along the longitudinal axis (X), a labyrinth seal (8b) intended to isolate the first enclosure (7) being formed between the cylindrical section (103) and a cylindrical bearing surface (11b) of the stator (4) of the turbomachine.

Images