TURBOMACHINE EQUIPPED WITH A DISCONNECTABLE ELECTRIC ENGINE AND AN AUTOMATIC ELECTRIC ENGINE CONNECTION DEVICE

Abstract

The invention relates to a turbomachine (1) comprising: - a longitudinal axis shaft (X) having a rear end supported by a stator (4) of the turbomachine via a rear bearing (6), - an electric machine (10), located at the rear of the turbomachine, comprising a stator and a rotor driven in rotation by the shaft, - a connecting device (25) configured to lock or unlock the rotor from the shaft (2) in rotation, and - an actuator (40) acting on the connecting device (25). According to the invention, the connecting device comprises a first carriage (34) carrying first teeth (32) that mesh with second teeth (33) of the shaft and translate axially between coupling and uncoupling positions, and a second carriage (54) connected to a movable body (42) of the actuator and fixed in movement to the first carriage (34), a bearing (51) being arranged between the first and second carriages (34, 50). Figure for the summary: Fig. 2

Description

Title of the invention: TURBOMACHINE EQUIPPED WITH A DISCONNECTABLE ELECTRIC MACHINE AND AN AUTOMATIC CONNECTION DEVICE FOR THE ELECTRIC MACHINE Technical field of the invention

[0001] The present invention relates to the field of turbomachinery, and in particular aircraft turbomachinery. 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 electrical power requirements that accompany the growing number of aircraft components and new functions, the question of turbomachine hybridization arises. The electric machine that equips accessory gearboxes, known by the English acronym AGB (for Accessory Gear Box), does not provide a significant increase in electrical power for all aircraft functions, and the efficiency of the conversion of mechanical power into electrical power is not optimal.

[0003] An electric machine is an electromechanical device based on electromagnetism that converts electrical energy, for example, into mechanical energy (generator mode) or, reversibly, produces electricity from mechanical energy (motor mode). The electric machine can also operate in generator mode as well as in motor mode.

[0004] It is known to integrate the electric machine at the rear of the turbomachine where there is space for its integration and where high temperature constraints and other layout difficulties apply. An example of an electric machine located at the rear of the turbomachine includes a rotor that is rotationally coupled to the rearmost low-pressure shaft of the turbomachine. However, the electric machine rotor is not mounted directly on a rear end of the low-pressure shaft but on a connecting shaft to avoid adding weight to the low-pressure shaft and also due to the increasingly smaller size of turbomachine shafts. The electric machine is mounted independently of the rest of the turbomachine to facilitate maintenance by means of a connecting device configured to couple or uncouple the shaft The connecting device is a pivoting mechanism that is fixed to the rotation of the electric machine's rotor on the low-pressure shaft, for example, in the event of a failure. Indeed, a malfunction of the electric machine can affect the low-pressure shaft, which can impact the operation of the turbomachine. In this case, the turbomachine may cease to operate on its own, which can be detrimental, and / or require intervention by an operator to prevent it from operating in flight. The connecting device comprises a rod or finger actuated by an actuator mounted on a stator of the turbomachine. This actuator acts directly on the connecting shaft to move it and disconnect it from the low-pressure shaft. An example of an electric machine at the rear of the turbomachine cooperating with a connecting device equipped with a finger is described in document FR-A1-3130323.

[0005] However, such direct contact induces significant friction between parts which are in different reference frames and which operate at different speeds, which can lead to a safety risk (for example, a fire) and impact the service life of the actuator and the connecting shaft.

[0006] There is a need to resolve all or part of the aforementioned drawbacks. Summary of the invention

[0007] The objective of the present invention is to provide a solution enabling a transition between means for connecting a turbomachine shaft driving a rotor of an electric machine which is independent and autonomous in terms of arrangement, and said shaft in a simple, economical, durable, repeatable and robust manner.

[0008] 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 which is supported by a turbomachine stator via a rear bearing, - an electric machine, located at the rear of the turbomachine, comprising an electric machine stator fixed to the turbomachine stator and an electric machine rotor capable of being driven in rotation by the low-pressure shaft, - a connection device configured to lock or unlock the electric machine rotor from the low-pressure shaft during rotation, and - at least one actuator fixed to the turbomachine stator and capable of acting on the connection device, the connection device comprising a first carriage which carries first teeth intended to mesh with second teeth carried by the low-pressure shaft and which is capable of moving along the longitudinal axis between a coupling position and a discoupling position, and a second carriage which is connected to a moving body of the actuator and which is fixed in movement to the first carriage, at least one bearing being arranged between the first carriage and the second carriage.

[0009] Thus, this solution makes it possible to achieve the aforementioned objective. In particular, such a configuration of the connection device prevents direct contact between a stator component and the rotor's low-pressure shaft, thereby canceling the drive of the electric machine's rotor on the low-pressure shaft. This connection device ensures the safety of the turbomachine by preventing fires caused by sparks due to excessive friction in a high-temperature, confined area and by eliminating certain risks of shaft breakage, for example. Furthermore, this solution is also non-destructive and reversible because it preserves the integrity of the components, allowing the electric machine to be disconnected for subsequent maintenance and reconnected once it is operational so that it is driven again by the low-pressure shaft.In addition, such a configuration requires very few structural modifications to the turbomachine. Maintaining the actuator at the stator reference frame helps to keep turbomachine costs down.

[0010] The turbomachine also comprises one or more of the following features and / or stages, taken alone or in combination: - the bearing comprising an inner ring which is attached to the first carriage, an outer ring which is attached to the second carriage and rolling elements installed between the inner and outer rings. - the first carriage has external splines designed to engage with internal splines of a rotor shaft of the electric machine so as to move relative to the rotor shaft. - the actuator comprises a fixed body and the moving body is mounted movable relative to the fixed body, the moving body being connected to the second carriage by at least one connecting rod. - the moving body moves along an axis that is offset or transverse relative to the longitudinal axis. - the turbomachine includes at least one elastic return element configured to exert a force on the moving body so as to disengage the rotor of the electric machine from the low-pressure shaft. - the turbomachine includes at least one elastic restoring element configured to exert a force on the moving body so as to maintain the solidification of the electric machine rotor with the low-pressure shaft. - The actuator is connected to an electronic unit that is configured to verify the operation of the connection device at least at each starting the turbomachine by successively connecting and disconnecting the rotor of the electric machine to the low-pressure shaft. - the actuator is connected to an electronic unit which is configured to disengage the rotor from the electric machine via the actuator according to a predetermined parameter or predetermined action. - the connection device includes coupling elements which have first teeth connected to the electrical machine and second teeth connected to the pressure base shaft. - the connection device includes sliding splines between the rotor shaft of the electric machine and at least one component of the connection device. - the first carriage is axially mobile relative to the rotor shaft by means of sliding splines between a coupling position and a discoupling position. - - The connecting rod is articulated at each of its first and second ends.

[0011] - - There are as many connecting rods as there are actuators

[0012] The invention relates to an aircraft comprising at least one turbomachine having any one of the aforementioned characteristics.

[0013] According to one aspect, the invention relates to a method for controlling a connection device of a turbomachine, implemented by an electronic unit, the turbomachine comprising an electric machine which is mounted at a rear end of a low-pressure shaft which is supported by a stator of the turbomachine via a rear bearing, and which includes an electric machine rotor which is capable of being driven into rotation by the low-pressure shaft via the connection device, the turbomachine comprising an actuator acting on the connection device and being connected to an electronic control unit, the method comprising at least one step of verifying the operation of the connection device at each start-up of the turbomachine by commanding the actuator to successively connect and disconnect the electric machine rotor from the low-pressure shaft. Brief description of the figures

[0014] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent upon reading the following detailed explanatory description, of embodiments of the invention given by way of purely illustrative and non-limiting examples, with reference to the accompanying schematic drawings in which:

[0015] - Fig. 1 is a schematic and partial axial cross-sectional view of an example of turbomachine to which the invention applies;

[0016] - Figure 2 is an example of an embodiment of a connection device between a rotor of an electric machine and a low-pressure shaft of a turbomachine according to the invention;

[0017] - Figure [Fig. 3] illustrates, in a partial axial cross-sectional view, a rotor of a electric machine connected to a low-pressure shaft of a turbomachine according to the invention;

[0018] - Figure [Fig. 4] illustrates, in a partial axial cross-sectional view, the rotor of the machine electrical which is no longer connected to the low-pressure shaft of the turbomachine as shown in the previous figure;

[0019] - Figure 5 represents an embodiment of an actuator connected to a device connection and elastic return means cooperating with said actuator according to the invention;

[0020] - Figure 6 represents another embodiment of an actuator connected to a connection device and elastic return means cooperating with said actuator according to the invention; and,

[0021] - Figure 7 represents another embodiment of an actuator connected to a connection device and elastic return means cooperating with said actuator according to the invention. Detailed description of the invention

[0022] Figure 1 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 engine, or generally a turbomachine comprising a fan or a propeller, whether shrouded or unshrouded. Only the rearmost or downstream portion of the turbomachine along the longitudinal axis X is shown in Figure 1.

[0023] In the present invention, and generally, the terms "upstream" and "downstream" are defined with respect to the circulation of gases or airflows 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," "outer," "inner," "internal," and "radial" are defined with respect to a radial axis Z extending 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.

[0024] The turbomachine 1 comprises a low-pressure shaft 2 extending along the longitudinal axis X 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.

[0025] The low-pressure shaft 2 is supported by a stator 4 of the turbomachine by means of several bearings. The stator 4 is, for example, a housing, and preferably an exhaust housing 5. More specifically, the turbomachine includes a rear bearing 6 enabling the stator 4 to support the rear end 3 of the low-pressure shaft 2. Optionally, the rear bearing 6 includes an inner ring 6a fixed to the rear end 3 of the low-pressure shaft 2 and an outer ring 6b fixed to a cylindrical bearing surface 7a of the turbomachine stator 4. The cylindrical bearing surface 7a is, for example, fixed to a bearing support 7. Rolling elements 6c, for example rollers, are arranged between the inner and outer rings 6a, 6b.

[0026] Advantageously, the rear bearing 6 is arranged in a first lubrication chamber 8. This first lubrication chamber 8 is, for example, closed by one or more seals located between walls (of shafts, ferrules, etc.) delimiting the first chamber 8. The first chamber 8 can be connected to a lubrication circuit supplied by a power source (not shown). The lubricant is preferably oil (in the form of a mist) which lubricates and cools at least the rear bearing 6.

[0027] The turbomachine 1 includes an electric machine 10 located at the rear of the turbomachine. The electric machine 10 is advantageously housed in a cavity 11 formed downstream of the rear end 3 of the low-pressure shaft. In other words, the electric machine 10 is arranged downstream of the rear end 3 of the low-pressure shaft. The cavity 11 is closed at least partially by a cover 12 which is attached to the stator 4, and in particular to the exhaust housing 5 of the turbomachine, by a bolted connection, for example. A thermal protection 13 can be applied to the inner wall of the cover 12 to protect the latter from the heat produced by the exhaust gases exiting the low-pressure turbine (not shown) of the turbomachine.

[0028] The electrical machine 10 is arranged more precisely within a second lubrication chamber 15, which is dedicated to the electrical machine 10 and is separate from the first lubrication chamber 8. The second chamber 15 is contained within the cavity 11. The second chamber 15 is delimited by walls (shafts, ferrules, etc.). Seals may be arranged between some of these walls.

[0029] The electric machine 10 comprises a stator 16 and a rotor 17. The electric machine 10 can operate alternately in generator mode and in motor mode. That is to say, the electric machine 10 can draw power from the lower shaft pressure 2 or inject power onto the low-pressure shaft 2. Advantageously, but not exclusively, the stator of the electric machine 16 comprises stator windings (or coils) and the rotor of the electric machine 17 comprises permanent magnets. The stator windings are intended to be electrically powered.

[0030] In the present example, the stator 16 of the electric machine 10 surrounds the rotor 17 of the electric machine 15 and is fixed to the stator 4 of the turbomachine. As shown in [Fig. 1], the hood 12 equipped with the thermal protection 13 advantageously surrounds the stator 16 of the electric machine 10.

[0031] Advantageously, but not exclusively, the electric machine stator 16 comprises a stator armature 18 which includes a first arm 19a and a second arm 19b located on either side of the electric machine stator 16 along the longitudinal axis X. The electric machine 10 may include a housing (not shown) which radially surrounds the stator 16 and the electric machine rotor 17. The first arm 19a may be fixed upstream of the housing and the second arm 19b may be fixed downstream of the housing. The first and second arms 19a, 19b extend radially towards the longitudinal axis X. The rotor 17 and the stator 16 are contained axially between the first and second arms 19a, 19b and optionally radially within the housing.

[0032] The electric machine stator 16 (and in particular the stator armature 18) includes a mounting flange 20 which is fixed to a mounting flange 21 of the turbomachine stator 4 (in particular the exhaust housing 5). The flanges 20, 21 extend radially and fastening members 26 allow them to be fixed together.

[0033] The rotor 17 of the electric machine 10 is advantageously driven by the low-pressure shaft 2 in a disconnectable manner. This is made possible by a connection device 25 configured to couple or disconnect the rotor 17 of the electric machine 10 from the low-pressure shaft 2. Disconnection can occur in the event of a failure of the electric machine 10 that would require the rotor 17 of the electric machine 10 to no longer be driven by the low-pressure shaft 2. The rotor 17 of the electric machine can become blocked and impact the operation of the turbomachine and its drag. Disconnecting the rotor 17 of the electric machine 10 prevents the low-pressure shaft 2 from shutting down, which would cause the turbomachine to stop. If the turbomachine is off but not blocked, the fan or propeller rotates naturally, thus limiting its drag.

[0034] To this end, and as shown in [Fig. 1], the turbomachine 1 comprises a connecting shaft 26 extending along the longitudinal axis X and downstream of the rear end 3 of the low-pressure shaft 2. The connecting shaft 26 extends the low-pressure shaft 2 towards the rear of the turbomachine 1. The connecting shaft 26 is advantageously coaxial with The low-pressure shaft 2. The connecting shaft 26 is attached to the rear end 3 of the low-pressure shaft in a removable manner to facilitate modular disassembly. The connecting shaft 26 includes, for example, a mounting flange 27 which is attached to a mounting flange 28 on the rear end 3. The attachment is achieved here by a bolt-type fastener so as to easily disconnect or connect the connecting shaft 26. Other similar fasteners can be used for this purpose. The axis of the threaded rod of this bolted connection is parallel to the longitudinal axis X. In this way, it is possible to remove the connecting shaft 26 to access the electric machine 10, which rests on this connecting shaft 26, and to remove it if necessary. The turbomachine 1 can continue to operate without the electric machine 10.

[0035] With reference to Figures 1 and 2, the electric machine 10 comprises a rotor shaft 29 which is, on the one hand, rotationally fixed to the rotor 17 of the electric machine 10 and, on the other hand, connected to the connecting shaft 26. Optionally, the rotor shaft 29 is centered and coaxial with the connecting shaft 26. The rotor shaft 29 is secured to the rotor 17, for example, by means of tight splines (not shown). The rotor shaft 29 is supported by at least one rotating bearing 30.

[0036] In the present embodiment, there are two rotating bearings 30, and these two rotating bearings are mounted, for example, between the first and second arms 19a, 19b, and the rotor shaft 29. Each rotating bearing 30 comprises an inner ring 30a integral with the rotor shaft 29 and an outer ring 30b integral with one of the first and second arms 19a, 19b of the stator armature 18. Rolling elements 30c are arranged between the inner and outer rings 30a, 30b. Advantageously, but not exclusively, the rolling elements of one of the bearings are balls and of the other bearings are rollers. In other words, the electric machine 10 is on its own rotating bearings 30. Furthermore, the electric machine 10 can be easily extracted by dismantling the fixing elements at the fixing flanges 21 and 22 and removing the rotor shaft 29.

[0037] The connection device 25 includes coupling members 31 designed to couple or uncouple the electric machine rotor from the low-pressure shaft 2. The coupling members 31 may be of the type known as "curving coupling" or of the dog clutch type. Curving coupling members allow centering, coupling, and torque transfer from the low-pressure shaft to the electric machine rotor or vice versa. Conversely, dog clutch members only allow coupling and torque transfer. Advantageously, the coupling members 31 include first teeth 32 connected to the rotor shaft 29, which are designed to mesh with second teeth 33 connected to the low-pressure shaft 2. The first and second teeth 32, 33 are presented in the form of an annular row and each preferably extends axially.

[0038] The connection device 25 also includes at least in part sliding grooves 35 allowing translational movement of one of the first and second teeth 32, 33.

[0039] In [Fig. 2], the connection device 25 includes, for example, a first carriage 34 which is suitable for being connected to the rotor shaft 29 on the one hand and to the low-pressure shaft 2 on the other. The first carriage 34 has an axis of revolution and extends between a first end 34a and a second end 34b. The axis of revolution is advantageously centered on the longitudinal axis X. The first carriage 34 advantageously, but not exclusively, includes the first teeth 32 which are arranged, for example, at the first end 34a. The second teeth 33 are advantageously, but not exclusively, carried by the low-pressure shaft 2. In particular, the second teeth 33 are positioned at a ferrule 38 integral with the connecting shaft 26. The second teeth 33 are complementary to the first teeth 32.

[0040] According to an advantageous feature, the first carriage 34 comprises external splines 36 extending along the longitudinal axis X. Advantageously, but not exclusively, the external splines 36 are arranged towards the second end 34b. The external splines 36 are designed to engage with internal splines 37, which in this example are carried by the rotor shaft 29. The internal splines 37 also extend along the longitudinal axis X. The internal splines 37 and the external splines 36 form the sliding splines. This interaction allows the first carriage 34 to be axially movable relative to the rotor shaft 29 between an engaged position (teeth 32, 33) and a disengaged position (teeth 32, 33). The sliding grooves also allow the connection device 25 to be directly connected to the electrical machine in order to take into account its operating state.

[0041] According to an alternative embodiment, the first carriage 34 is coupled to the rotor shaft between the coupling position and the uncoupling position.

[0042] Advantageously, but not exclusively, the turbomachine includes at least one actuator 40 which is fixed to the stator of the turbomachine and which is capable of acting on the connecting device 25. In particular, the movement of the first carriage 34 is controlled by an actuator 40 between the coupling position and the uncoupling position. The actuator 40 includes, for example, a fixed body 41 which is intended to be fixed to the stator of the turbomachine and a movable body 42 mounted movable relative to the fixed body 41 between a first position and a second position. The stator of the turbomachine here may be the stator armature 18 or the housing exhaust 5.

[0043] In the example shown, the fixed body 41 is supported by a radial flange 43 of the second arm 19b. The radial flange 43 is fixed to a radial mounting flange of the stator. In particular, an annular wall 19c, centered on the longitudinal axis X, extends axially from the second arm 19b (in particular downstream) and the radial flange 43 extends radially from an end of the annular wall 19c that is opposite the annular wall 19b.

[0044] The actuator 40 comprises, for example, a tubular section 44 and an annular base 45 extending radially from one end of the wall of the tubular section 44. The annular base 45 rests on an external surface of the annular wall 19c, and the tubular section 44 passes through a radial opening formed in the annular wall 19c. The tubular section 44 extends radially according to this embodiment.

[0045] The moving body 42 of the actuator 40 slides inside the fixed body 41 between the first and second positions. The axis A of movement of the moving body 42 is offset or transverse with respect to the longitudinal axis X. The moving body 42 is in the form of a piston 46 which, in this example, moves along the radial axis. The piston 46 is advantageously cylindrical and has a circular cross-section. The moving body 42 includes a flange 47 which extends radially, at a first end 46a, from the outer wall of the piston 46. Advantageously, but not exclusively, the piston 46 extends inside the tubular section 44 and the flange 47 is arranged radially outside the annular base 45. Of course, the piston 46 can move through the radial opening in the annular wall 19c.In this example, the actuator 40 is mounted radially (radial movement of the moving body 42) to utilize the available space and reduce its overall size. Of course, the actuator 40 could also be installed in the turbomachine 1 so that the moving body 42 moves axially. In this case, the axis of movement of the moving body 42 is parallel to and offset from the longitudinal axis X.

[0046] The actuator 40 is connected to a power source 49, for example, an electrical power source. The electrical power may be supplied by the electric machine. The actuator 40 may also be powered by a pneumatic or hydroelectric power source. Alternatively, the power source may be an electrical circuit powered by an electric generator which is driven by a high-pressure shaft. In this case, the electrical circuit may include a battery.

[0047] In the first position of the moving body 42, the first carriage 34 is coupled to the low-pressure shaft 2 (coupling position) and in the second position of the When the moving body 42 is in the second position, the first carriage 34 is disengaged from the low-pressure shaft 2 (disengaged position). Alternatively, when the moving body 42 is in the second position, the first carriage 34 is in the engaged position, and when the moving body 42 is in the first position, the first carriage 34 is in the disengaged position. The actuator 40 is reversible, and the position of the moving body 42 depends on the state of the electrical power supply. The actuator 40 has an inherent ability to change state.

[0048] Optionally, the actuator 40 is configured to have an active state and an inactive state. In the active state, the actuator 40 is supplied with electrical energy, and in the inactive state, the actuator 40 is not supplied with electrical energy.

[0049] The connecting device 25 includes, for example, a second carriage 50 which is fixed to the first carriage 34 during movement. The second carriage 50 can be connected to the moving body 42 of the actuator 40. The second carriage 50 is configured to ensure the position of the first carriage 34. Furthermore, the second carriage 50 advantageously transmits forces to the first carriage 34. In this example, the second carriage 50 has an axis of revolution advantageously centered on the longitudinal axis X and extends between a first end 50a and a second end 50b. The second carriage 50 optionally extends radially around the first carriage 34.

[0050] Between the first carriage 34 and the second carriage 50, at least one bearing 51 is arranged. The arrangement of the bearing 51 ensures a smooth transition from the fixed reference frame (second carriage 50 connected to the actuator 40) to the rotating reference frame (first carriage 34, which moves in translation and possibly in rotation when connected to the low-pressure shaft 2). Furthermore, such a configuration exhibits high robustness. More specifically, the configuration does not cause a temperature rise within the system, no wear on the parts between the rotating reference frame and the fixed reference frame, and has a high load-transmission capacity.

[0051] In the illustrated example, there are two levels 51. Of course, a single level or a different number of levels is conceivable.

[0052] Each bearing 51 comprises an inner ring 52a which is fixed to the first carriage 34 and an outer ring 52b which is fixed to the second carriage 50. Rolling elements 52c are installed between the inner and outer rings 52a, 52b. These rolling elements 52c are preferably angular contact balls. Such an arrangement of these bearings 51 allows for a high axial load and avoids axial play. Of course, the rolling elements can have O or X contact, as is well known to those skilled in the art. The rolling elements 52c can also be angular contact rollers.

[0053] Each level 51 is advantageously, but not exclusively, immobilized axially. Advantageously, the inner ring of the first bearing 51 is mounted against a shoulder 53 formed on the first carriage 34. Conversely, the outer ring 52b is axially held between a spacer 54 mounted on the first carriage 34 and a shoulder 55 formed on the second carriage 50. The outer ring 51b of the second bearing 51 is mounted against a shoulder 56 formed on the second carriage 50, while the inner ring of the second bearing 51b is held by a nut 57. This nut is mounted, for example, around the first carriage 34 and has an internal thread that engages with an external thread of the first carriage 34. The nut 57 is mounted here at the second end of the first carriage 34. Advantageously, but not exclusively, the nut 57 applies a tightening torque to both bearings 51. In this way, the cohesion between the first carriage 34, the bearing(s) 51, and the second carriage is ensured. 50 is guaranteed.

[0054] The connection between the second carriage 50 and the moving body 42 is achieved by at least one connecting rod 58. The latter is configured to transmit the force of the actuator 40 to the second carriage 50. The connecting rod 58 comprises a first end 58a which is mounted via a pivot joint with a second end 46b of the piston 46. The connecting rod 58 comprises a second end 58b which is mounted via a pivot joint with the second end 50b of the second carriage 50. In this example, the axis of the pivot joints is perpendicular to the radial axis and to the longitudinal axis X. Furthermore, in this example, only the connecting rod 58 is articulated between the moving body 42 of the actuator 40 and the second carriage 50. The force of the actuator 40 in the radial direction is transmitted to the first carriage 34 in the axial direction.The addition of the second carriage 50 and the connecting rod 58 increases the service life of the connection device 25 because it prevents direct contact between the moving body 42 of the actuator 40, which is located in a fixed frame, and the low-pressure shaft 2, which is located in a rotating frame. The low-pressure shaft 2 rotates, for example, at very high speeds of around 10,000 rpm, and the moving body 42 of the actuator 40 acting directly on a rotating element could generate sparks, wear, etc.

[0055] Advantageously, but not limitingly, there are as many connecting rods 58 as actuators 40.

[0056] Figure 3 illustrates the connecting device 25 in the coupling position. In this figure, the first teeth 32 of the first carriage 34 are engaged with the second teeth 33 of the connecting shaft 26. The external splines of the first carriage 34 are also coupled with the internal splines of the rotor shaft 29. The actuator 40 is in its active state, i.e., it is supplied with electrical energy, and the moving body 42 is in a first position in which it holds the first carriage 34 coupled with the low-pressure shaft 2 (here the connecting shaft 26). In this way, the low-pressure shaft 2 drives the rotor 17 of the electric machine 10 in rotation via the teeth 32, 33 which are engaged with each other in the coupling position of the carriage 34.

[0057] Figure 4 illustrates the connection device 25 in the disengaged position. The first teeth 32 are disengaged from the second teeth 33. To achieve this, the first carriage 34, which carries the first teeth 32, is moved upstream by the actuator 40. To move from the engaged position to the disengaged position when necessary, the actuator 40 (in its active state) applies a force radially outwards, which allows the connecting rod 58, driven by the piston 46, to pivot and the first and second carriages 34, 50 to move upstream. In this position, the rotor 17 of the electric machine 10 is no longer driven by the low-pressure shaft 2. As also illustrated, the second end 34b of the first carriage 34 is advantageously, but not limited to, abutting against a thrust surface 59 carried by the rotor shaft 29 of the electric machine 10.Once the first trolley 34 is decoupled, the actuator 40 is in its inactive state, i.e., it is no longer supplied with electrical energy.

[0058] Alternatively, when the actuator is in an inactive state then the connection device 25 is in the coupling position and when the actuator is in an active state then the connection device 25 is in the uncoupling position.

[0059] Figures 5 to 6 illustrate embodiments of at least one actuator 40 cooperating with at least one elastic return element 48. The latter is capable of acting on the moving body 42 of the actuator 40. In particular, the return element 48 makes it possible to exert a force on the moving body 42. Advantageously, the force of the elastic return element 48 tends to assist the transition from the first position to the second position or to oppose the transition from the second position to the first position of the actuator 40. In other words, the elastic return element 48 is configured so as to exert a force on the moving body 42 in order to disengage the rotor 17 of the electric machine 10 from the low-pressure shaft 2.This ensures the secure disengagement between the first carriage 34 and the low-pressure shaft 2 in the rest state (turbomachine stopped) or in the event of a malfunction (e.g., an in-flight shutdown) with the low-pressure shaft 2 in autorotation. Conversely, the elastic return element 48 is configured to exert a force on the moving body 42 in order to maintain the connection of the electric machine rotor 10 with the low-pressure shaft 2.

[0060] Advantageously, but not limitingly, the force exerted by the elastic return element 48 is for example a function at least of a force corresponding to a friction component at the level of the internal and external splines (sliding splines 35) between the first carriage and the rotor shaft of the electric machine 10. In particular, the force exerted by the elastic restoring element 48 is greater than the force corresponding to the friction component.

[0061] Such a configuration of the elastic return element 48 makes it possible on the one hand to compensate for a failure of the actuator 40 for example or in case of loss of power of the latter and on the other hand, to install one or more actuators 40 with a low power which allows an economic gain.

[0062] The return element 48 is chosen from the group comprising at least one spring, one coil and one Belleville-type washer.

[0063] In [Fig. 5], the elastic return element 48 comprises two springs 48a, 48b which are mounted between the base 45 of the moving body 42 of the actuator 40 and the flange 47 of the fixed body of the actuator 40. According to this arrangement, the springs 48a, 48b assist in disengaging the rotor of the electric machine 10 from the low-pressure shaft 2. In this embodiment, each spring 48a, 48b consists of two Belleville washers 48a1, 48a2, 48b1, 48b2 arranged one on top of the other. Advantageously, but not exclusively, the washers 48a1, 48a2, 48b1, 48b2 are arranged in opposition. This arrangement of the washers advantageously results in high forces. Of course, other types of arrangements or return elements are possible. The force of the elastic return element here is greater than the force applied by the actuator 40 for the coupling, which is not electrically powered.In this scenario, the actuator 40 must be supplied with electrical energy in order to maintain the coupling position of the first carriage 34. In this example, the actuator 40 can exert a force of 3000 N and the arrangement of the return elements allows it to exert a force of 3500 N.

[0064] Alternatively, the operation is reversed when the springs are arranged radially above the base 45 of the moving body 42. In this configuration, the springs 48a, 48b assist in coupling the rotor of the electric machine with the low-pressure shaft. In other words, the springs 48a, 48b apply a force to the moving body 42 of the actuator 40 in the direction of the connecting device 25. The springs 48a, 48b advantageously reduce the force exerted by the actuator 40.

[0065] In [Fig. 6], the elastic return element 48 comprises opposing springs. The elastic return element 48 here comprises five springs 48a, 48b, 48c, 48d, 48e, of which three 48a, 48b, 48c are mounted radially below the base 45 of the moving body 42, and two 48d, 48e are mounted radially below the base 45. In this embodiment, each spring 48a, 48b, 48c, 48d, 48e consists of two Belleville washers stacked one on top of the other. Advantageously, but not limitingly, the washers are arranged in such a way as to be in opposition. Of course, other types of arrangements or return elements are possible. In this embodiment, the three springs 48a, 48b, 48c allow the rotor of the electric machine 10 to be disengaged from the low-pressure shaft 2, and the two springs 48d, 48e contribute to the force exerted by the actuator 40 on the first carriage 34. The elastic return force of the three springs 48a, 48b, 48c is greater than the elastic return force of the two springs 48a, 48b. More precisely, the return force of the elastic return element is greater here than the force applied by the actuator 40, which is not electrically powered, and than the elastic return force of the springs 48d, 48e. In other words, the elastic return elements 48 generate a preload taking up part of the load of the actuator and the actuator 40 taking up only the remaining load. Following this embodiment, the elastic return elements 48 are mounted in a housing 61 which is fixed to the annular wall 19c. The housing serves as a guide for the elastic return elements and / or the piston. The housing 61 also serves as a protection for the piston 46. Of course, the piston can itself serve as a guide for the elastic return elements.

[0066] In [Fig. 7], the elastic return element 48 comprises four springs 48a, 48b, 48c, 48d (as illustrated in [Fig. 3]). Two springs 48d, 48e are mounted on either side of the base 45 of the moving body 42. Advantageously, each spring comprises two Belleville washers arranged one on top of the other in opposition. The return forces of the two springs on each side of the base are identical. The arrangement of the elastic return elements 48 on either side of the base 45 is considered to be in equilibrium. In particular, in this example, the return elements 48 exert a force that opposes the displacement forces of the carriage 50, and the actuator 40 exerts an additional force to maintain a coupled or uncoupled position.

[0067] According to an alternative, the actuator 40 is dimensioned so as to counter the force of the return elements 48 as well as so as to guarantee the coupling between the first carriage 34 and the low pressure shaft 2.

[0068] According to an advantageous feature, the actuator 40 is connected to an electronic unit 60 which is installed, for example, in the aircraft. The electronic unit 60 can be a computer known as a FADEC (Full Authority Digital Engine Control). The electronic unit 60 is configured to send control commands to the actuator 40 so that the latter acts on the connection device 25. The electronic unit 60 is also capable of receiving information relating to the operating state or environment of the electric machine 10, the torque and / or vibration level of the low-pressure shaft, or an action (by a pilot, for example) to control the actuator 40. This information is derived by Examples of sensors and relate for example to the temperature in the electric machine 10 or in its environment, the torque of the rotor shaft 29, a variation or interruption of the current in the electric machine 10, the torque of the low pressure shaft 2, the vibration level of the low pressure shaft 2, etc.

[0069] By way of example, the electronic unit 60 is configured to verify the operation of the connection device 25 at least each time the turbomachine is started by successively connecting and disconnecting the rotor 17 of the electric machine 10 from the low-pressure shaft 2. This configuration makes it possible to determine whether the connection device 25 can connect or disconnect from the low-pressure shaft 2 to ensure the safety of the turbomachine under all circumstances, particularly in flight, and to comply with aeronautical standards. In this way, the operation of the connection device 25 is guaranteed on every flight to mitigate the risk of failure, as the turbomachine can operate without the electric machine 10 until the next inspection.

[0070] The electronic unit 60 is also configured to disengage the rotor 17 from the electric machine 10 according to a predetermined parameter or predetermined order. Such an action is preferably carried out in flight.

[0071] The electronic unit 60 is also configured to lock the rotor of the electric machine to the low-pressure shaft. Such an action is carried out, for example, on the ground after checking the condition of the electric machine 10.

[0072] We will now describe an example of a method for controlling a connecting device 25 as described previously. The method includes at least one step for verifying the operation of the connecting device 25 at each start-up of the turbomachine, in which the electronic control unit 60 sends a command to the actuator 40 to successively connect and disconnect the rotor 17 of the electric machine 10 from the low-pressure shaft 2. The command is sent automatically at start-up by the electronic control unit 60, for example. This verification step may include several successive couplings and uncouplings. During this step, the moving body 42 exerts a force on the first carriage 34 via the second carriage 50.

[0073] If an elastic return element 48 is present, it can assist in coupling or uncoupling depending on the state of the actuator 40. Information regarding the state of the connecting device 25 is sent to the electronic unit 60 after this verification step. If coupling and uncoupling are successful, the information takes a positive value, indicating that the connecting device 25 is in operation. If coupling and uncoupling have not occurred, information concerning a malfunction of the connecting device 25 is transmitted to the electronic control unit 60. The malfunction is by For example, a failure of piston 46 of actuator 40 to move. If the piston does not move, then there is no change in position of the second carriage. Advantageously, but not exclusively, a proximity or displacement sensor (not shown) may be provided at the actuator 40 and / or at least one of the first and second carriage(s).

[0074] The method includes a step of disengaging the rotor 17 from the electric machine 10, in which the electronic control unit 60 sends a command to the actuator 40 to disengage the first carriage 34 based on a predetermined parameter or action. To this end, the electronic unit 60 analyzes received information to detect a particular event or actions received from a driver. The information is obtained, as stated above, from sensor measurements, for example. Monitoring by the electronic unit 60 is preferably carried out at several regular intervals. When a torque value, for example, exceeds a predetermined value, the electronic unit 60 commands the disengagement of the first carriage 34. To do this, the electronic unit 60 sends a command to the actuator 40.The predetermined value is stored in a memory of the electronic unit 60, which is compared with the measured value(s). Other means of detecting a malfunction are possible. Alternatively, the pilot can order the disengagement of the first trolley 34. Disengagement is thus carried out on demand or in case of malfunction. The pilot can order disengagement, for example, in the event of extreme temperature readings, a flight with few or no passengers, and / or a turbomachine shutdown in flight.

[0075] The connection device 25, as described, directly linked to the electric machine 10 and cooperating with an actuator 40, as described, reliably, robustly, and reversibly ensures the coupling and decoupling of the electric machine 10 with the low-pressure shaft 2. Furthermore, the arrangement of this connection device 25 and the actuator 40 can be tested at any time, and preferably before each flight, to guarantee the availability of the disconnection function in case of a malfunction in flight. The movement capacity of at least the actuator 40 is verified, which also implies the operating capacity of the connecting rod 58, the carriages 34, 50, and / or the bearings. The system is then considered automatic.

Claims

Demands

1. Turbomachine (1), particularly for aircraft, comprising: - a low-pressure shaft (2) extending along a longitudinal axis (X) to a rear end (3) which is supported by a stator (4) of the turbomachine via a rear bearing (6), - an electric machine (10), located at the rear of the turbomachine, comprising an electric machine stator (16) fixed to the stator (4) of the turbomachine and an electric machine rotor (17) capable of being driven in rotation by the low-pressure shaft (2), - a connecting device (25) configured to lock or unlock the rotor in rotation from the low-pressure shaft (2), and - at least one actuator (40) fixed to the stator (4) of the turbomachine and capable of acting on the connecting device (25),characterized in that the connection device (25) comprises a first carriage (34) which carries first teeth (32) intended to mesh with second teeth (33) carried by the low-pressure shaft (2) and which is capable of moving along the longitudinal axis (X) between a coupling position and a discoupling position, and a second carriage (54) which is connected to a movable body (42) of the actuator (40) and which is fixed in movement to the first carriage (34), at least one bearing (51) being arranged between the first carriage (34) and the second carriage (54).

2. Turbomachine (1) according to the preceding claim, characterized in that the bearing (51) comprises an inner ring (52a) which is attached to the first carriage (34), an outer ring (52b) which is attached to the second carriage (50) and rolling elements (52c) installed between the inner and outer rings.

3. Turbomachine (1) according to the preceding claim, characterized in that the first carriage (34) has external splines (36) intended to engage with internal splines (37) of a rotor shaft (29) of the electric machine (10) so as to move relative to the rotor shaft (29).

4. Turbomachine (1) according to any one of the preceding claims, characterized in that the actuator (40) comprises a fixed body (41) and the moving body (42) is mounted movable relative to the fixed body (41), the moving body (42) being connected to the second carriage (54) by at least one connecting rod (57).

5. Turbomachine (1) according to the preceding claim, characterized in that the moving body (42) moves along an axis (A) offset or transverse with respect to the longitudinal axis (X).

6. Turbomachine (1) according to any one of the preceding claims, characterized in that it comprises at least one elastic return element (48) configured to exert a force on the moving body (42) so as to disengage the electric machine rotor (17) from the low-pressure shaft.

7. Turbomachine (1) according to any one of claims 1 to 5, characterized in that it comprises at least one elastic return element (48) configured to exert a force on the moving body (42) so as to maintain the connection of the electric machine rotor (17) with the low-pressure shaft.

8. Turbomachine (1) according to any one of the preceding claims, characterized in that the actuator (40) is connected to an electronic unit (60) which is configured to verify the operation of the connection device (25) at least at each start of the turbomachine by successively connecting and disconnecting the electric machine rotor (17) from the low pressure shaft (2).

9. Turbomachine (1) according to any one of the preceding claims, characterized in that the actuator (40) is connected to an electronic unit (60) which is configured to disengage the electric machine rotor (17) via the actuator (40) according to a predetermined parameter or predetermined action.

10. A method for controlling a connection device (25) of a turbomachine (1) according to any one of claims 1 to 9, characterized in that the method comprises at least one step of verifying the operation of the connection device (25) at each start of the turbomachine in which the electronic control unit (60) sends a control order to the actuator (40) to successively connect and disconnect the electric machine rotor (17) from the low pressure shaft (2).

11. A method according to claim 10, characterized in that it comprises a step of disengaging the electric machine rotor (17) in which the electronic control unit (60) sends a control order to the actuator (40) to disengage the first carriage (34) according to a predetermined parameter or predetermined action.

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