Turbine module with motor rotor

Abstract

The invention relates to a fan module (100) for an aircraft turbine (10), comprising: a fan (14) comprising a disk (32a) carrying fan blades (30), a rotor (62a) of an electric motor (62), the rotor (62a) having a substantially annular shape and being coaxially mounted downstream of the fan (14), an annular support (90) for the rotor (62a), the downstream end (90b) of the annular support being fixed to the rotor (62a) and the upstream end (90a) being fixed to the fan disk (32). According to the invention, the support (90) is fixed to the disk (32a) by shear bolts (99) configured to break when the torque transmitted by the disk (32a) to the support (90) exceeds a predetermined threshold. The invention also relates to an aircraft turbine comprising such a module (100). Abstract: Figure 2.

Description

Technical Field

[0001] In particular, the invention relates to an aircraft turbine module equipped with an electric machine rotor. Background Art

[0002] The prior art includes in particular documents FR-A1-2 842 565, which describes a turbine equipped with an electric machine, as well as documents FR-A1-2 976 623, EP-A1-1 382 802, WO 2018 / 115763 A1, FR-A1-2 393 227, FR-A1-3 081 523 and EP-A2-2 602 434.

[0003] The aviation community is now raising many questions about the implications of hybrid engines for commercial aviation. The use of electrical energy is now being considered not only for aircraft functions but also for the electrification of turbines.

[0004] This observation has led to the study of hybrid engine architecture solutions combining fossil fuel energy and electrical energy to ensure the driving of the propulsion part (turbofan) and the supply of some engine and / or aircraft functions.

[0005] In particular, these architectures can be based on high bypass ratio and reducer type architectures, but can also be based on multi-body (two or three) architectures. In these architectures, the turbomachine comprises a low-pressure body and a high-pressure body, each body comprising a shaft connecting the rotor of the compressor to the rotor of the turbine.

[0006] It is known to equip aircraft turbines with electric motors. For example, recall that an electric motor is an electromechanical device based on electromagnetism that enables the conversion of electrical energy into work or mechanical energy. This process is reversible and can be used to generate electricity.

[0007] Therefore, depending on the end use of the machine, the term:

[0008] -A generator is an electric machine that produces electrical energy from mechanical energy.

[0009] -A motor is an electrical machine that generates mechanical energy from electrical energy.

[0010] The electric machine can also operate in motor mode and generator mode.

[0011] In normal operation, two types of forces are applied to the rotor of an electric machine: torque (drag torque or motor torque, depending on the operating conditions) and radial force.

[0012] The motor's rotor is attached to the fan's disc via a flange and screws. This allows the disc to rotate the motor's rotor. This attachment also ensures the motor's rotor is securely held. The screws are loaded with tension, and the friction between the two faces of the flange maintains the connection to withstand the motor's radial forces and torques. The screw size is determined based on the flange's implant radius and the coefficient of friction at the flange level.

[0013] In extreme events, such as the loss of a blade from a fan disk, the disk becomes extremely unbalanced and begins to orbit due to the large imbalance. This imbalance can cause eccentricity, which in turn causes the motor's air gap to close. Because the eccentricity caused by the blade loss is much larger than the motor's rotor-stator gap, the motor experiences rotor-stator contact.

[0014] This rotor-stator contact of the motor slightly increases the magnetic radial forces, but above all results in significant purely mechanical forces: a portion of the unbalanced forces passes through the motor via the flanges and the screws, generating radial forces via the flanges, but also friction torques between the rotor and stator at the motor level. If allowed to continue, this friction at the motor level (particularly the contact between the magnets of the electric rotor and the magnetic steel sheets of the stator) can lead to fires in the motor and / or potential blockage of the fan disk.

[0015] The present invention provides solutions to at least some of the above problems. Summary of the Invention

[0016] The present invention provides a fan module for an aircraft turbine, the fan module comprising:

[0017] - a fan, comprising a disk carrying fan blades,

[0018] - a rotor of the electric motor, the rotor being of substantially annular shape and being mounted coaxially downstream of the fan,

[0019] An annular support for the rotor, the downstream end of the annular support being attached to said rotor and the upstream end of the annular support being attached to the fan disk.

[0020] According to the present invention, the support portion is attached to the disc by means of breakable screws configured to break when the torsional torque transmitted from the disc to the support portion exceeds a predetermined threshold value.

[0021] With the present invention, in the event of a major accident such as blade breakage, the imbalance of the fan disk and the resulting eccentricity will cause the breakable screws to break.

[0022] As a result, the electric rotor will no longer be rotated by the fan disc and, due to the magnetic forces between the electric rotor and its stator, will become a stator component. By decoupling the motor rotor from the fan disc, the invention therefore makes it possible, in particular, to avoid the fire risks associated with rotor-stator contact of mobile electric motors and, in particular, to avoid obstruction of the fan disc.

[0023] The cross-section of the breakaway screw is designed to ensure resistance in normal operation and to break at a certain force caused by the rotor-stator contact on the motor. For example, assuming a quarter of the radial force is transmitted through the motor, the breakaway screw can be sized to break in the event of a blade breakage while still ensuring resistance in the extreme and design operating conditions.

[0024] The system according to the present invention may include one or more of the following features, taken alone or in combination with one another:

[0025] - the support comprises a downstream cylindrical section for mounting the rotor and a first upstream annular flange for attachment to the disk, the flange comprising orifices for the passage of the breakable screws;

[0026] - the downstream section is connected to the first flange by a frustoconical wall flaring downstream;

[0027] - a downstream section comprising an upstream annular stop on which the rotor is intended to bear and a downstream thread for attaching a nut configured to bear on the rotor in order to keep it axially tightened against the stop;

[0028] - the downstream section comprises a radially inner annular rim for retaining the breakable screw after breaking;

[0029] - said rim comprises through-going orifices for the passage of oil;

[0030] - the fan comprises inter-blade platforms attached to the disk, the module further comprising an annular collar for retaining the downstream ends of these platforms, the collar comprising an outer peripheral edge surrounding and retaining the downstream ends of the platforms, and an inner peripheral edge comprising a second annular flange for attachment to the disk, the second flange comprising orifices for the passage of attachment screws;

[0031] - the disc comprises, at its outer periphery, a series of teeth defining between them slots for mounting the roots of the blades, each of these teeth comprising, at its downstream end, an ear for attaching the collar, holes being formed in these ears for passing the attachment screws;

[0032] - the second flange is inserted between the disc and the first flange, the breakable screw passes through the orifice in the first flange and the orifice in the second flange, and the attachment screw passes through the orifice in the second flange and not through the orifice in the first flange;

[0033] The breakable screws are located on a first circumference and the attachment screws are located on a second circumference, the inner diameter of the first circumference being smaller than the diameter of the second circumference.

[0034] The invention also relates to an aircraft turbomachine comprising a module as described above, the turbomachine comprising a stator of an electric machine surrounding a rotor of the electric machine of the module. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Other features and advantages of the present invention will become apparent from the following detailed description and for an understanding of the same, reference is made to the accompanying drawings, in which:

[0036] [ Figure 1 ] Figure 1 is a schematic axial cross-sectional view of an aircraft turbine;

[0037] [ Figure 2 ] Figure 2 is a partial schematic half view of an axial cross section of an aircraft turbine equipped with an electric motor;

[0038] [ Figure 3 ] Figure 3 is a schematic axial cross-sectional view of a motor rotor and a support portion of the motor rotor;

[0039] [ Figure 4 ] Figure 4 is a partial schematic view of an axial cross section of the attachment of the flange of the ferrule and the rotor of the electric machine to the fan disk of the turbomachine;

[0040] [ Figure 5 ] Figure 5 is a partial schematic view of an axial cross section of a connection between a fan blade root and a fan collar;

[0041] [ Figure 6 ] Figure 6 is a schematic axial cross-sectional view of a breakable screw according to the present invention;

[0042] [ Figure 7 ] Figure 7 is a schematic perspective view of a fan tray;

[0043] [ Figure 8 ] Figure 8 yes Figure 7 a partial schematic radial cross-sectional view of a fan disk; and

[0044] [ Figure 9 ] Figure 9 is similar to Figure 2 Schematic axial cross-sectional view of a breakable screw breaking. DETAILED DESCRIPTION

[0045] First refer to Figure 1 , Figure 1 A twin-body and twin-flow aircraft turbine 10 is schematically shown.

[0046] The turbine 10 generally comprises a gas generator 12 and, upstream, a fan 14. The fan 14 is surrounded by a fan casing 16, which is surrounded by a nacelle 18 which surrounds and extends along a major portion of the gas generator 12.

[0047] The gas generator 12 includes two main bodies, a low-pressure (or BP, basse pressure) main body 12a and a high-pressure (or HP, haute pressure) main body 12b, each of which includes a compressor and a turbine.

[0048] The terms “upstream” and “downstream” are considered along the main direction F of the gas flow in the turbine 10 , which direction F is parallel to the longitudinal axis A of the turbine.

[0049] Furthermore, according to the convention in this application, the terms “inner” and “outer” are defined radially with respect to the longitudinal axis of the turbomachine, in particular the axis of rotation of the rotor of the compressor.

[0050] The gas generator 12 includes, from upstream to downstream, a low-pressure compressor 20 , a high-pressure compressor 22 , a combustion chamber 24 , a high-pressure turbine 26 , and a low-pressure turbine 28 .

[0051] The fan 14 comprises an annular row of blades 30 driven in rotation by a fan shaft 32 connected in particular to the rotor of the low-pressure body 12a via a speed reducer 33. However, in an alternative embodiment of the invention not shown, the turbine may not comprise a speed reducer.

[0052] The gas flow through the fan (arrow F) is divided by the annular separator nose 34 upstream of the gas generator 12 into a radially inner annular flow and a radially outer annular flow, the radially inner annular flow being referred to as the main flow 36, which supplies the gas generator 12, and the radially outer annular flow being referred to as the secondary flow, which flows between the gas generator 12 and the nacelle 18 and provides most of the thrust of the turbine.

[0053] The inlet casing 40 structurally connects the gas generator 12 to the fan casing 16 and the nacelle 18. The inlet casing 40 includes an annular row of radially inner arms 42 extending into the primary flow 36 and an annular row of radially outer straighteners 44 (of the OGV type for the outlet guide vanes) extending into the secondary flow 38. The arms 42 are generally limited in number (less than ten) and may be tubular and traversed by auxiliary equipment. The number of vanes 44 (OGVs) is generally greater than ten.

[0054] The rotor of the low-pressure body 12a and the fan shaft 32 are guided upstream by bearings 46, 48 and 50. These bearings 46, 48, 50 are of the ball or roller type, each comprising an inner ring mounted on the shaft to be guided, an outer ring carried by an annular bearing support, and rolling elements between the rings.

[0055] In a known manner, the reducer 33 is of the epicyclic gear train type and comprises a sun gear centered on axis A, a ring gear extending around the axis, and planet gears meshing with the sun gear and the ring gear and carried by a planet carrier. The ring gear is fixed and securely connected to the support of bearings 46, 48. The planet carrier is rotatable and connected to an output shaft 54 ​​of the reducer, which also comprises an input shaft 56 meshing with the sun gear. The input shaft 56 of the reducer is coupled to the main shaft of the low-pressure main body, and the output shaft 54 ​​is coupled to the fan shaft 32.

[0056] The input shaft of the reducer is guided by a bearing 50 carried by a bearing support, and the output shaft 54 ​​is guided by bearings 46 and 48 .

[0057] The bearing supports 52 , 60 extend about the axis A and are fixed components connected to the inlet housing 40 .

[0058] Figure 2 yes Figure 1 A larger scale view of a portion of the fan disk 32a and the reducer (in Figure 2 6 and 7. A larger scale view of the region Z between the fan and the motor 62 (not shown) in which the motor 62 is mounted. This allows the module 100 according to the invention to be shown, comprising the fan and the rotor 62a of the motor 62.

[0059] This annular zone Z, in addition to being axially delimited upstream by the fan disk 32 a and downstream by the reducer, is also delimited radially inwardly by the output shaft 54 ​​of the reducer and radially outwardly by elements that internally delimit the flow duct I of the main flow 36. These elements include an upstream annular collar 64 and a downstream inner annular wall 66 which, when connected to the radially inner end of the arm 42, forms part of the inlet casing 40.

[0060] The wall 66 extends as an extension of the collar 64, which is an inner collar and is connected to an outer collar 70 by an annular row of stationary vanes 68. The collars 64, 70 define between them the air inlet of the flow duct I of the main flow 36. The collar 70 extends between the aforementioned separator nose 34 and an outer annular wall located downstream of the collar 70, which forms part of the inlet housing 40 when it is connected to the radially outer end of the arm 42.

[0061] The annular region Z is divided into two annular sections, an upstream annular section and a downstream annular section, by a bearing support 52. In the example shown, this support has a generally frustoconical shape that flares downstream. The upstream radially inner end of the support carries the outer ring of the bearing 46, the inner ring of which is attached to the output shaft 54. The downstream radially outer end of the support 52 is attached to the inlet housing 40.

[0062] The outer ring of the or each bearing 48 is attached approximately midway to a support portion 52, leaving the or each inner ring attached to an output shaft 54. To this end, the bearing support portion 52 comprises two annular extensions, an upstream annular extension 52a and a downstream annular extension 52b. The upstream extension 52a extends from the bearing 46 to a radially outer annular flange for attachment to the downstream extension 52b, while the downstream extension 52b extends from a radially inner annular flange for attachment to the upstream extension 52a to a radially outer annular flange for attachment to the inlet housing 40.

[0063] The or each outer ring of the bearing 48 is attached to the downstream extension 52b.

[0064] The downstream section of the zone Z represents a portion of the enclosure E which is used to support the bearings 46, 48 (and 50- Figure 1 ) and the reducer, which is accommodated in the enclosure and is arranged axially between the bearings 46, 48 on the one hand and the bearing 50 on the other hand. An oil mist is present in the enclosure.

[0065] The upstream section of the zone Z represents the mounting location of the motor 62 , which is therefore separated from the enclosure E by the bearing support 52 .

[0066] The motor 62 is generally annular in shape and includes a rotor 62a and a stator 62b. The rotor 62a has a generally annular shape extending around the axis A and is coaxially mounted downstream of the fan 14. The rotor 62a can also be mounted upstream of the fan 14, but has a larger implementation radius downstream of the fan 14.

[0067] The rotor 62 a is supported by an annular support portion 90 , which is substantially cylindrical in shape. The rotor 62 a is arranged around the annular support portion 90 .

[0068] A downstream end 90 b of the annular support 90 is attached to the rotor 62 a , and an upstream end 90 a of the support is attached to the fan disk 32 a .

[0069] Thus, the support portion 90 enables the fan disk 32a to rotate the rotor 62a. The stator 62b also has a generally cylindrical shape and is integrally contacted with the collar 64.

[0070] The collar 64 cooperates in a sealing manner with the bearing support 52 (cooperation not shown). The sealing is provided by a labyrinth seal, the annular scraper of which is carried, for example, by the collar 64 and the wear-resistant coating is carried by the bearing support 52.

[0071] For example, the stator 62 b is connected by a cable to a control circuit which, in this case, passes through the tubular arm 42 of the inlet housing 40 .

[0072] After passing through the fan 14 and / or the main flow 36 , the motor 62 (particularly the stator 62 b thereof) is positioned as close to the main flow as possible, ie, as close to the collar 64 .

[0073] The collar 64 also keeps the inter-blade platform 110 attached to the downstream end 111 of the disk 32a. This collar 64 comprises an outer peripheral edge 65, which surrounds and holds the downstream end 111 of the platform 110, and an inner peripheral edge 67, which comprises a second annular flange 112 for attachment to the disk 32a, which is located at the level of the inner end of the second flange 112. The second flange 112 comprises orifices 113 for the passage of attachment screws 114.

[0074] According to the present invention, the support portion 90 is attached to the disc 32a by means of breakable screws 99 (Les vis fusibles) configured to break when the torsional torque transmitted from the disc 32a to the support portion 90 exceeds a predetermined threshold.

[0075] The support 90 comprises a cylindrical downstream section 91 for mounting the rotor 62 a and a first upstream annular flange 92 for attachment to the disk 32 a , this flange 92 comprising orifices 93 for the passage of breakable screws 99 .

[0076] The downstream section 91 is connected to a first flange 92 by a frustoconical wall 90 c flaring downstream.

[0077] As in Figure 3 As best seen in the figure, the downstream section 91 comprises an upstream annular stop 94 on which the rotor 62a is intended to bear, and a downstream thread 95 for attaching a nut 89 configured to bear on the rotor 62a so as to keep the rotor 62a axially tightened against the stop 94.

[0078] The downstream section 91 comprises a radially inner annular rim 96 which serves to retain the broken off screws 99. In fact, when the rotor 62a is uncoupled from the fan disk, the rotor 62a becomes the stator and the broken off screws 99 are then accumulated on the inner face of the downstream section 91 and are retained by the annular rim 96.

[0079] This annular rim 96 enables the rotor 62a to be balanced. In practice, balancing the rotor 62a can be achieved by locally machining the annular rim 96 in accordance with the observed imbalance, in order to correct the observed imbalance. This annular rim 96 also contributes to the rigidity of the downstream section 91, thereby helping to maintain the air gap between the rotor 62a and the stator 62b of the electric machine 62.

[0080] The annular rim 96 comprises through-holes 97 for the passage of oil, which, in the event of an oil leak in this region, enable the oil to be released in the direction of the arrow 98 .

[0081] As in Figure 4 , the second flange 112 is inserted between the disc 32a and the first flange 92. The breakaway screws 99 pass through the apertures 93 in the first flange 92 and the apertures 115 in the second flange 112. The attachment screws 114 pass through the apertures 113 in the second flange 112, but not through any apertures in the first flange 92.

[0082] The breakaway screws 99 are located on a first circumference, and the attachment screws 113 are located on a second circumference, the inner diameter of the first circumference being smaller than the inner diameter of the second circumference. Thus, the second flange 112 is separated from the rotor of the motor, so that the rotor of the motor can be uncoupled without releasing the fan tray from the second flange 112.

[0083] As in Figure 5 As shown in FIG, the outer end of the inner periphery 67 comprises an annular scraper 120 for cooperating with a wear-resistant coating 121 of the outer periphery 65 of the collar 64. The scraper 120 and the coating 121 form a labyrinth seal.

[0084] Figure 6 An example of a breakable screw 99 according to the present invention is shown. This screw 99 comprises a screw head 99a and a thread 99b. The breakable feature of the screw 99 is shown by an intermediate section 99c of the screw having a reduced cross-section, which is arranged between the head 99a and the thread 99b to serve as a breaking portion, in particular during shearing.

[0085] The screw is fastened with a hexagonal key. Other clamping methods can also be used. Figure 7 and Figure 8As can be seen in the drawing, the disc 32a comprises, at its outer periphery, a series of teeth 35 defining between them slots 37 for mounting the roots of the blades, each of these teeth 35 comprising, at its downstream end, an ear 39 for attaching a collar.

[0086] Orifices 116 for the passage of attachment screws are formed in these ears 39 and are intended to be positioned opposite the orifices 113 for the passage of screws for attaching the second flange 112. Orifices 117 for the passage of breakaway screws are formed in the disk 32a, are positioned radially inwardly with respect to the orifices 116, and are intended to face the orifices 93 for the passage of breakaway screws in the first flange 92 and the orifices 115 in the second flange 112.

[0087] Figure 9 Similar to Figure 2 , and shows an example of a breakaway screw 99 failing, for example, due to the loss of a blade, thereby releasing rotor 62a from fan disk 32a. In practice, such a blade loss would create a significant imbalance on fan disk 32a, which would in turn result in radial forces on first flange 92 of fan disk 32a. Therefore, the breakaway screw is dimensioned to fail in the presence of shear, which is caused by the frictional torque of the rotor on the stator of the motor, transmitted by disk 32a, and the radial forces on first flange 92 of the fan disk.

[0088] Here it can be seen that the rotor 62a is in contact with the stator 62b and that the rotor itself has become the stator. Thus, fragments 99a from the broken breakable screw can accumulate on the inner face of the downstream section 91 of the support 90, in particular on the annular rim 96.

[0089] Figure 9 It also enables illustration that the fan disk 32 a remains connected to the inner periphery 67 of the collar 64 by the second flange 122 .

Claims

1. A fan module (100) for an aircraft turbine (10), comprising: a fan (14) comprising a disk (32a) carrying fan blades (30), a rotor (62a) of an electric motor (62) having a substantially annular shape and mounted coaxially downstream of the fan (14), an annular support (90) for the rotor (62a), the downstream end (90b) of the annular support being attached to the rotor (62a) and the upstream end (90a) of the annular support being attached to the fan disk (32a), Characterized in that the support portion (90) is attached to the disk (32a) by a breakable screw (99), the breakable screw being configured to break when the torsional torque transmitted from the disk (32a) to the support portion (90) exceeds a predetermined threshold.

2. The module (100) according to claim 1, wherein The support (90) comprises a downstream cylindrical section (91) for mounting the rotor (62a) and a first upstream annular flange (92) for attaching the disk (32a), the first upstream annular flange (92) comprising an orifice (93) for passing the breakable screw (99).

3. The module (100) according to claim 2, wherein The downstream cylindrical section (91) is connected to the first upstream annular flange (92) by a frustoconical wall (90c) flaring downstream.

4. The module (100) according to claim 2 or 3, wherein The downstream cylindrical section (91) comprises an upstream annular stop (94) on which the rotor (62a) is intended to bear, and a downstream thread (95) for attaching a nut (89) configured to bear on the rotor (62a) so as to keep the rotor axially tightened against the stop (94).

5. The module (100) according to claim 2 or 3, wherein The downstream cylindrical section (91) comprises a radially inner annular rim (96) for retaining the breakable screw (99) after breaking.

6. The module (100) according to claim 5, wherein The rim (96) comprises through-going orifices (97) for the passage of oil.

7. The module (100) according to claim 2 or 3, wherein The fan (14) comprises inter-blade platforms (110) attached to the disk (32a), the module further comprising an annular collar (64) for retaining the downstream ends (111) of these platforms (110), the collar (64) comprising an outer peripheral edge (65) surrounding and retaining the downstream ends (111) of the platforms (110) and an inner peripheral edge (67), the outer peripheral edge comprising a second annular flange (112) for attachment to the disk (32a), the second annular flange (112) comprising orifices (113) for passing attachment screws (114).

8. The module (100) according to claim 7, wherein The disc (32a) comprises a series of teeth (35) at its outer periphery, the series of teeth defining slots (37) between the teeth for mounting the roots of the blades (30), each of the teeth (35) comprising an ear (39) at its downstream end for attaching the collar (64), apertures (116) for passing the attachment screws (114) being formed in these ears (39).

9. The module (100) according to claim 7, wherein The second annular flange (112) is inserted between the disk (32a) and the first upstream annular flange (92), the breakable screw (99) passes through the orifice (93) in the first upstream annular flange (92) and the orifice (115) in the second annular flange (112), and the attachment screw (114) passes through the orifice (113) in the second annular flange (112) without passing through the orifice in the first upstream annular flange (92).

10. The module (100) according to claim 9, wherein The breakable screws (99) are located on a first circumference and the attachment screws (114) are located on a second circumference, the inner diameter of the first circumference being smaller than the diameter of the second circumference.

11. An aircraft turbomachine (10) comprising a module (100) according to any one of the preceding claims, the turbomachine (10) comprising a stator (62b) of the electric machine (62) surrounding the rotor (62a) of the electric machine (62) of the module (100).

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