reducer equipped with an electric motor

Abstract

The invention relates to a planetary gear reducer (21) for an aircraft turbine engine (1), the reducer (21) comprising a sun gear (30) and a ring gear (33) centered on a longitudinal axis X, and a planet carrier (32) carrying at least one planet gear (31) rotatably mounted around a planet axis A parallel to the longitudinal axis X, the sun gear (30) being rotatable around the longitudinal axis, the planet gear (31) being in mesh with the sun gear (30) and the ring gear (33), the planet carrier (32) being movable around the longitudinal axis, and the ring gear (33) being fixed against rotation. According to the invention, the reducer (21) comprises an electric machine (50) integrated with the reducer, the electric machine comprising a rotor (51) mounted on the planet carrier (32) for rotation around the longitudinal axis X, and a stator (52) mounted on the ring gear (33). ABSTRACT DRAWING: Figure 2.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of reduction gears, in particular to the field of reduction gears for aircraft turbomachines. The present invention is particularly directed to reduction gears equipped with electric machines and to turbomachines comprising such reduction gears. BACKGROUND

[0002] The prior art includes documents US-A1-2019 / 085714, WO-A1-2019 / 243558 and US-A-4291233.

[0003] Aircraft turbomachines, for example double-flow turbomachines, generally comprise a fan with a shroud, arranged at the inlet of the turbomachine and rotated by a low-pressure shaft. A reduction gear can be interposed between the fan and the low-pressure shaft, so that the fan is rotated at a lower speed than the low-pressure shaft. The reduction in speed also makes it possible to increase the size of the fan, thus making it possible to achieve very high bypass ratios. In addition to the propulsion of the aircraft, the turbomachine uses a Permanent Magnet Alternator (PMA) and an Accessory Gear Box (AGB) to ensure the production of electric current to power various equipment items, for example the lighting of the aircraft's cabin or the air conditioning and pressurization system of the aircraft's cabin.

[0004] It is known to equip turbomachines, in particular the Accessory Gear Box of the electric machines. An electric machine is an electromechanical device based on electromagnetism that makes it possible to convert electrical energy into mechanical energy (generator mode) or, reversibly, to generate electrical energy from mechanical energy (motor mode). An electric machine can perform well in generator mode as in motor mode.

[0005] In the face of environmental challenges in the field of aviation and the demand for electrical power, which grows with the number of new functions and equipment items of the aircraft, the question of hybridization of the turbomachine arises. The electric machines as described above are not able to provide a significant gain in electrical power for all the functions of the aircraft, and the efficiency of the conversion of mechanical energy into electrical energy is not optimal. In addition, the integration of electric machines in the various zones of the turbomachine is complex and is limited by the overall size requirement, the temperature resistance of certain components of the electric machine, the proximity, the performance of the turbomachine itself, etc. SUMMARY

[0006] The aim of the present invention is to provide an electric machine that is easy to integrate to provide additional electrical power in a turbomachine, without substantially modifying the components of the turbomachine.

[0007] According to the application, this is achieved by means of a reduction gear with epicyclic gear train for an aircraft turbomachine, the reduction gear comprising a sun gear and a ring gear centered on a longitudinal axis, and a planet carrier carrying at least one planet gear mounted so as to be able to rotate about a planet gear axis parallel to the longitudinal axis X, the sun gear being able to rotate about the longitudinal axis, the planet gear meshing with the sun gear and the ring gear, the planet carrier being able to move about the longitudinal axis, and the ring gear being fixed and not rotating, the reduction gear comprising an electric machine integrated in the reduction gear, the electric machine comprising a rotor and a stator, the rotor being mounted on the planet carrier so as to be driven to rotate about the longitudinal axis X, the stator being mounted on the ring gear.

[0008] This solution thus makes it possible to achieve the objectives mentioned above. In particular, this configuration makes it possible to avoid cluttering the turbomachine on the one hand because the electric machine is integrated into the reduction gear, and on the other hand to control the position of the rotor and the stator with an acceptable air gap, using the reduction gear arrangement (fixed ring gear and movable planet carrier). Furthermore, because the components of the reduction gear and of the electric machine can be assembled independently of one another, and also independently of the other components of the turbomachine, the integration of the electric machine into the reduction gear makes it possible to provide a modular approach. The fact that the electric machine and the reduction gear are located in the same place also makes installation and removal easier.

[0009] The reduction gear also comprises one or more of the following features, taken separately or in combination:

[0010] - the stator of the electric machine extends around the rotor of the electric machine.

[0011] - the stator comprises a first annular part centered on the longitudinal axis and extending downstream of the ring gear along the longitudinal axis.

[0012] - in particular, unlike the rotor and the stator of the prior art, which are located at the center of the reduction gear, the rotor and the stator downstream of the reduction gear are more accessible, which means that the electric machine must be installed simultaneously with each component of the reduction gear.

[0013] - the first annular part is fitted on the ring gear or formed as an integral part of the ring gear.

[0014] - the rotor comprises a second annular part mounted on the cage of the planet carrier.

[0015] - the electric harness extends outside the ring gear, at least one electric cable circulating inside the electric harness, the at least one electric cable being connected to the stator of the electric machine.

[0016] - the planet carrier comprises an annular cage carrying a sliding bearing on which the planet gear is mounted.

[0017] The application also relates to an aircraft turbomachine comprising a drive shaft having a longitudinal axis X and a fan having a fan shaft, the fan shaft being driven in rotation by the drive shaft through a reduction gear having any one of the above characteristics, an annulus being attached to a stator casing of the turbomachine and a planet carrier being coupled to the fan shaft to drive the fan shaft in rotation around the longitudinal axis.

[0018] The turbomachine also comprises one or more of the following characteristics taken separately or in combination:

[0019] - the sun gear is coupled to the drive shaft to drive the sun gear in rotation around the longitudinal axis.

[0020] - the lubrication enclosure is at least partially delimited by a shroud, the shroud at least partially forming a radially inner wall of the fan shaft and of the main duct.

[0021] - the reduction gear and the electric machine are arranged in the lubrication enclosure, the lubrication enclosure being arranged upstream of the inner casing.

[0022] The application also relates to a method for the modular assembly of the above-mentioned turbomachine, the method comprising the following steps:

[0023] - assembling a reduction gear as described above,

[0024] - integrating an electric machine with the reduction gear by mounting a rotor on the planet carrier and mounting a stator on the annulus, and

[0025] - mounting the assembly comprising the reduction gear and the integrated electric machine in the lubrication enclosure of the turbomachine. BRIEF DESCRIPTION OF DRAWINGS

[0026] The application will be better understood and other objects, details, characteristics and advantages of the application will become more clearly apparent from the following detailed description of embodiments thereof, given by way of purely illustrative and non-limiting example, with reference to the drawings in which:

[0027] [ Figure 1 ] Figure 1 is a schematic axial cross-sectional view of a double-flow turbomachine having a reduction gear according to the application;

[0028] [ Figure 2 ] Figure 2 is a schematic axial cross-sectional detailed view of a fan module of a double-flow turbomachine having a reduction gear according to the application, the reduction gear being interposed between a drive shaft and a fan shaft of the turbomachine;

[0029] [ Figure 3 ] Figure 3 is an upstream axial half-section perspective view of a reduction gear according to the application; and

[0030] [ Figure 4 ] Figure 4 is a downstream axial half-section perspective view of a reduction gear according to the application. DETAILED DESCRIPTION

[0031] Figure 1 An axial cross-sectional view of a turbomachine 1 having a longitudinal axis X to which the application applies is shown. The turbomachine shown is a double-flow and double-body turbomachine for installation on board of an aircraft according to the application. Of course, the application is not limited to this type of turbomachine.

[0032] In the present application, the terms "upstream", "downstream", "axial" and "axially" are defined with respect to the direction of the gas flow in the turbomachine, but also along the longitudinal axis (even in the case of a radial axis). The terms "radial", "radially", "internal" and "external" are also defined with respect to the radial axis Z which is perpendicular to the axis X of the turbomachine. Figure 1 In the figures, the terms "left" and "right" are defined from left to right in the figures. The terms "upstream" and "downstream" are defined from upstream to downstream in the turbomachine.

[0033] This turbomachine 1 having a double-flow and double-body comprises a fan 2 mounted upstream of a gas generator 3. The fan 2 comprises a plurality of fan blades 4 extending radially from the periphery of a disc 5 (see Figure 2 ) around which a fan shaft 6 extends. The fan 2 is surrounded by a fan casing 7 which at least partially carries a nacelle 8. The nacelle surrounds the gas generator 3 and extends along the longitudinal axis X.

[0034] The gas generator 3 comprises, from upstream to downstream, a low-pressure compressor 9, a high-pressure compressor 10, a combustion chamber 11, a high-pressure turbine 12 and a low-pressure turbine 13. The high-pressure (HP) compressor 10 is connected to the HP turbine by a HP shaft to form a first body called high-pressure body. The low-pressure (BP) compressor 9 is connected to the BP turbine by a BP shaft 14 to form a second body called low-pressure body. The HP shaft extends inside the BP shaft 14.

[0035] The air flow F entering the turbomachine through the fan 2 is divided by a separator nose 15 of the turbomachine into a primary air flow Fl which flows in particular through the gas generator 3 in a primary duct 16 and into a secondary air flow F2 which flows around the gas generator 3 in a secondary duct 17. The primary duct 16 and the secondary duct 17 are coaxial. The secondary air flow F2 is ejected through a secondary nozzle 18 which terminates the nacelle 8, while the primary air flow Fl is ejected outside the turbomachine through an ejection nozzle 19 located downstream of the gas generator. The primary and secondary air flows merge at the outlet of their respective nozzles.

[0036] With reference to Figure 2 The fan shaft 6 is connected to a drive shaft which drives the fan shaft in rotation about the longitudinal axis by means of a power transmission mechanism 20. In this example, the drive shaft is the low-pressure shaft 14. The power transmission mechanism 20 makes it possible to reduce the speed of the fan 2 to a speed lower than the speed of the low-pressure shaft 14. On the other hand, the power transmission mechanism 20 makes it possible to arrange a fan with a large diameter in order to increase the bypass ratio. Advantageously, the bypass ratio of the fan is higher than 10. Preferably, the bypass ratio is between 12 and 18.

[0037] The power transmission mechanism comprises a reduction gear 21, which is, in this case, a reduction gear with an epicyclic gear train. The reduction gear with an epicyclic gear train is housed in a lubrication enclosure 22 which is arranged upstream of the gas generator. The lubrication enclosure makes it possible to lubricate the reduction gear 21 and the rotating guide bearings. In particular, the lubrication enclosure 22 is arranged in an annular inner casing 23 which extends upstream by an aerodynamic-shaped inlet cone 24.

[0038] The inner casing 23 comprises an annular rotor shroud 23a which rotates about the longitudinal axis X relative to an annular stator shroud 23b of the inner casing 23. The disc 5 of the fan 2 is mounted in the shroud 23a. The stator shroud 23b is structurally connected to the inlet casing 27 by first stator vanes 25 (abbreviation “IGV”) which extend radially into the primary air flow Fl about the longitudinal axis X. The inlet casing 27 carries the splitter nose 15 upstream and extends downstream by means of the interduct casing 29. Of course, the rotor shroud 23a, the disc 5 form a rotor assembly, while the inlet casing 27, the stator vanes 25 and the stator shroud 23b form a stator assembly. Second stator vanes 26 (called “OGV”) structurally connect the inlet casing 27 to the fan casing 7, which extend radially into the secondary air flow about the longitudinal axis X. Advantageously, the lubricant which occupies the lubrication enclosure 22 is an oil in mist.

[0039] The reduction gear 21 with epicyclic gear train generally comprises a sun gear 30 (or inner planet gear), at least one planet gear 31, a planet carrier 32 and a ring gear (outer planet gear) 33. In this example, the reduction gear comprises a plurality of planet gears, for example three planet gears. The sun gear 30 is centered on a longitudinal axis X and is rotatably coupled to the drive shaft (here the BP shaft) along the longitudinal axis X by a sun gear shaft 34. The sun gear shaft comprises a first element for cooperation with a complementary second coupling element carried by the sun gear. The planet gears 31 are carried by the planet carrier 32. Each planet gear 31 meshes with the outer toothing of the sun gear 30 and with the inner toothing of the ring gear 33. The planet gears 31 are each guided for rotation about a planet gear axis A parallel to the longitudinal axis X. The planet gear axis A is fixed to the planet carrier 32. The ring gear 33 surrounds the sun gear 30 and is centered on the longitudinal axis X.

[0040] The planet carrier 32 is rotatably coupled to the fan shaft 6 and the ring gear 33 is fixed to the stator casing of the turbomachine. In other words, the ring gear 33 is fixed and does not rotate. In this way, the sun gear 30 forms the inlet of the reduction gear and the planet carrier 32 forms the outlet of the reduction gear. The fan shaft 6, the sun gear shaft 34 and the drive shaft (BP shaft 14) rotate about the longitudinal axis and are coaxial. In this example of embodiment, the planet carrier 32 and the fan shaft 6 are integral. In other words, the planet carrier and the fan shaft are formed as one piece. The fan shaft 6 is guided for rotation relative to the fixed structure of the turbomachine by at least one bearing 35. Advantageously, the at least one bearing is a ball bearing. In particular, the bearing comprises an inner ring 36 mounted on the fan shaft 6, an outer ring 37 carried by a ring-like support 38 and rollers 39 (balls) between the inner ring and the outer ring. The ring-like support 38 is fixed to the fixed structure of the turbomachine.

[0041] In Figure 3 and Figure 4 , the ring gear 33 is formed from a coaxial first part 33a and a second part 33b. Each first part 33a and second part 33b comprises a section of the toothing of the ring gear. Each first ring gear part and second ring gear part comprises a ring-like flange 40a, 40b extending outwardly along a radial axis at one end. The ring-like flanges are attached to each other by attachment members 41 such as screws, bolts, nuts or similar elements. The flanges 40a, 40b are located at a level of a median plane perpendicular to the longitudinal axis. The ring gear 33 is also attached to a ring gear carrier 42 which is attached to the ring-like support 38 of the bearing 35 by attachment members as described above. A closing cover 43 of the enclosure 22 radially covers sections of the ring gear 33 and the ring gear carrier 42.

[0042] In the present example of embodiment, the turbomachine further comprises an electric machine 50 to benefit from additional electric power. The electric machine 50 serves as a generator and as a motor. In case the electric machine serves as a motor, it can provide a propulsion function in addition to the fan and the mineral fuel. In generator mode, the electric machine provides additional electric power of for example at least one hundred kilowatt.

[0043] The electric machine comprises a rotor 51 and a stator 52. As shown in Figure 3 and Figure 4 , the electric machine is arranged in the lubricated enclosure 22 (in the gas generator) so that it can also be cooled by the lubricant. The temperature in the lubricated enclosure is at most about 150°C, which is acceptable for the electric machine. This is because the temperature of the components of the electric machine (electrical conductors, electrical insulators, magnetic circuit, temperature sensor, exciter) should generally not exceed this value. Moreover, the high dynamics generated by the electric machine are directly discharged into the lubricant oil.

[0044] The enclosure 22 is at least partially delimited by shrouds 23b, 28 which at least partially form the support 38 of the bearing 35, the fan shaft 6 and the radially inner wall of the main duct. Air circulates outside the enclosure 22, for example between the support 38 and the assembly of the inner casing 23 and the duct inter-casing 27.

[0045] The electric machine is integrated into the reduction gear 21 which makes it possible to facilitate the integration into the gas generator, in particular into the lubricated enclosure 22. To this end, the rotor 51 is mounted on the planet carrier 32 to be driven in rotation about the longitudinal axis and the stator 52 is mounted on the ring gear 33.

[0046] The stator 52 comprises a first part 53 which is a ring part about the longitudinal axis and which is fixed to the ring gear 33. Here, the first ring part 53 extends downstream of the ring gear 33 along the longitudinal axis X. The first ring part 53 is an assembly part on the ring gear (i.e. the first ring part is separate and / or made using a different manufacturing method). The stator 52 (first ring part) can be attached to the ring gear 33 by gluing, screwing (screws / bolts / nuts), etc. Alternatively, the ring part 53 is formed as an integral part of the ring gear (i.e. as one part). The stator 52 extends around the rotor 51. As shown in Figure 3 and Figure 4 , advantageously, the first ring part 53 is carried by a second portion 33b of the ring gear (arranged downstream of the reduction gear).

[0047] As for the rotor 51, it also comprises a second annular part 55 around the longitudinal axis X. The rotor 51 can be attached to the planet carrier by gluing, screwing (screws / bolts / nuts), etc. The first and second parts are concentric. It will be understood that the second part 55 also extends downstream of the reduction gear. The length li of the first annular part 53 is substantially less than the length l2 of the second part 55. In order to achieve the mounting of the rotor 51 on the planet carrier, the planet carrier comprises an annular cage 58 centred on the longitudinal axis. A first flank 59 is mounted upstream of the reduction gear, while a second flank 60 is mounted downstream of the reduction gear. Each of the first and second flanks comprises an axial aperture 61 (see Figure 3 ), which passes through the walls of the first and second flanks on either side along an axis parallel to the longitudinal axis X. Each planetary gear is rotatably mounted on a bearing 62 around a planetary gear axis. Preferably, but not exclusively, each bearing is a plain bearing. Each bearing is coaxial with the planetary gear axis, and the free ends 62a, 62b of the bearing are respectively mounted at the level of the corresponding aperture in the first flank 59 and in the second flank 60. An oil film circulates between the outer surface 63 of each bearing and the inner surface 64 of each planetary gear. This oil film is continuously fed by a lubrication circuit 69 in order to improve the performance of the reduction gear and to prolong the service life of the plain bearings.

[0048] As shown in Figure 3 and Figure 4 , the second annular part 55 is mounted on the outer periphery of the second flank 60. To this end, the second flank 60 has an annular collar 65 extending outwards along a radial axis. The collar 65 is housed in a groove 66 in the second annular part 55. The groove 66 is arranged in a radially inner surface 67 of the first annular part 53 and faces the longitudinal axis. The second annular part 55 also has a radially outer surface 68 (opposite the radially inner surface along the radial axis) and carries permanent magnets. The permanent magnets are arranged to face the coils carried by the first annular part 53. Of course, conversely, the second annular part can comprise the coils and the first annular part can comprise the permanent magnets.

[0049] With reference to Figure 4 , an electrical wiring harness 70 extends radially outwards from the ring gear 33 and outwards from the reduction gear. In particular, the electric machine 50 comprises at least one electrical cable 71 connecting the electrical stator to an electronic control system (for example a FADEC or Full Authority Digital Engine Control) to enable electrical power to be supplied to the electric machine. Advantageously, other electrical cables of the electric machine 50 are collected in this single wiring harness 70. The electrical wiring harness 70 extends outside the enclosure through the housing arms or stator blades. The fact that the ring gear 33 of the planetary gear reduction is fixed is particularly advantageous for this electrical wiring harness to exit outside the enclosure towards the outer member of the turbomachine.

[0050] For example, when the electric machine 50 is running in motor mode, the electric machine adds torque to the outlet of the reduction gear 21 to provide more power to the fan. One or more batteries can be installed in the aircraft and electrical energy is brought to the electric machine 50 through the electrical cable 71. This electrical energy enables the rotor 51 of the electric machine 50 to rotate. The electrical energy is thus converted into mechanical energy. The energy input is supplied through the fan shaft 6 to assist the rotation of the fan 2.

[0051] When the electric machine is in generator mode, the electric machine 50 takes torque from the reduction gear 21 to provide additional electrical power. The torque is transmitted through the shaft 14 to the reduction gear 21 and to the fan shaft 6 and the electric machine 50. The electric machine converts the mechanical energy into electrical energy to power electrical devices (non-exhaustive list) such as batteries attached to the aircraft, aircraft devices or electric motors attached to the aircraft.

[0052] As we have seen, the integration of the electric machine 50 on the reduction gear 21 enables the reduction gear + electric machine assembly to be modular. To this end, during the installation, the reduction gear 21 is first assembled with the various components of the reduction gear. Then, the electric machine 50, as well as the rotor and the stator of the electric machine, are installed on the reduction gear, where the stator is installed on the ring gear 33 and the rotor is installed on the planet carrier 32. The stator and the rotor extend downstream of the reduction gear, in particular downstream of the ring gear and the planet carrier. This position facilitates the installation and removal of the electric machine on the reduction gear. If the stator is integral with the ring gear, the stator is assembled on the reduction gear at the same time as the ring gear. The electrical cable 71 is connected to the electric machine 50. Finally, the reduction gear and the electric machine are installed as a single unit in the lubrication enclosure 22, the assembly thus being easily modular. This assembly slides from upstream to downstream, such that the sun gear shaft 34 is coupled to the drive shaft (BP shaft). Then, the disc 5 and the fan shaft 6 are inserted from upstream of the inner casing to couple the fan shaft 6 to the planet carrier 32. The inlet cone 24 is then installed on the inner casing to close the fan module.

Claims

1. Reducer (21) with epicyclic gear train for aeronautical turbomachinery (1), said reducer (21) comprising a sun gear (30) and a ring gear (33) centred on a longitudinal axis X, and a planet carrier (32) carrying at least one planet gear (31) mounted so as to be able to rotate about a planet gear axis A parallel to said longitudinal axis X, said sun gear (30) being able to rotate about said longitudinal axis, said planet gear (31) being in mesh with said sun gear (30) and with said ring gear (33), said planet carrier (32) being able to move about said longitudinal axis and said ring gear (33) being fixed so as not to rotate, characterised in that, The speed reducer (21) comprises an electric machine (50) integrated with the speed reducer, the electric machine comprising a rotor (51) mounted on the planetary carrier (32) to be driven in rotation about the longitudinal axis X and a stator (52) mounted on the ring gear (33), an electric wire bundle (70) extending outside the ring gear (33) and at least one electric cable (71) circulating inside the electric wire bundle (70), the at least one electric cable being connected to the stator (52) of the electric machine (50).

2. The speed reducer (21) according to claim 1, characterized in that The stator (52) of the electric machine (50) extends around the rotor (51) of the electric machine.

3. The speed reducer (21) according to claim 1 or 2, characterized in that The stator (52) comprises a first annular member (53) centered on the longitudinal axis and extending along the longitudinal axis downstream of the ring gear (33).

4. The speed reducer (21) according to claim 3, characterized in that The first annular member (53) is fitted on the ring gear (33) or formed as an integral part of the ring gear (33).

5. The speed reducer (21) according to claim 4, characterized in that The rotor comprises a second annular member (55) mounted on an annular cage (58) of the planetary carrier (32).

6. The speed reducer (21) according to claim 1 or 2, characterized in that The planetary carrier (32) comprises an annular cage (58) carrying a sliding bearing (62) on which the planetary gears are mounted.

7. An aircraft turbomachine (1) comprising a drive shaft (14) having a longitudinal axis X and a fan (2) having a fan shaft (6) driven in rotation by the drive shaft through a speed reducer (21) according to any one of Claims 1 to 6, the ring gear (33) being attached to a stator casing of the aircraft turbomachine and the planetary carrier (32) being coupled to the fan shaft (6) to drive the fan shaft in rotation about the longitudinal axis.

8. The aircraft turbomachine according to claim 7, characterized in that, The speed reducer (21) and the electric machine (50) are arranged in a lubrication enclosure (22) arranged upstream of an inner casing.

9. - The aircraft turbomachine according to claim 7 or 8, characterized in that, The sun gear is coupled to the drive shaft (14) to drive the sun gear in rotation about the longitudinal axis.

10. A method for modular assembly of an aircraft turbomachine (1) according to claim 9, characterized in that, The method comprises the following steps: - assembling a speed reducer (21) according to any one of Claims 1 to 6, - integrating an electric machine (50) with the speed reducer (21) by mounting the rotor (51) on the planetary carrier and mounting the stator (52) on the ring gear (33), and - mounting the assembly of the speed reducer and integrated electric machine (50) in a lubrication enclosure (22) of the aircraft turbomachine.

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