Turbine engine module provided with an electric machine

Abstract

The invention relates to a module (100) for a turbine engine, in particular for an aircraft turbine engine, comprising a shaft extending in an axial direction and an electric machine (110) comprising: - a rotor (120) rotatably coupled to the shaft of the module, the rotor comprising a disc (122) and magnetic elements (124) arranged regularly around the periphery of the disc; and - a stator (130) rigidly attached to a casing of the module comprising a ring and coils (134) distributed annularly inside the ring of the stator, the coils being arranged outside the magnetic elements of the rotor in a radial direction, characterised in that each coil is radially movable between a first end position and a second end position, each coil being held in the first position in normal operation and moved toward the second end position in the event of the rotor moving radially towards the coil of the stator.

Description

[0001] DESCRIPTION

[0002] TITLE OF THE INVENTION: TURBOMACHINE MODULE EQUIPPED WITH AN ELECTRIC MACHINE

[0003] TECHNICAL FIELD

[0004] The technical field of the invention is that of turbomachines equipped with an electric machine.

[0005] The present invention relates in particular to an aircraft turbomachine module equipped with an electric machine.

[0006] PRIOR ART

[0007] The technical background includes in particular documents EP 3 029 814 A2, WO 2012 / 159108 A2, US 2015 / 0171722 A1 and EP 2 369 720 A1.

[0008] The aeronautical world is currently asking many questions about the relevance of using hybrid engines for commercial aviation. The use of electrical energy is currently being considered not only to meet aircraft functions but also to electrify turbomachine functions. This observation leads to the study of hybrid engine architecture solutions, combining fossil fuel energy and electrical energy to drive the propulsion part (fan or turbine of the turbomachine) and power certain engine and / or aircraft functions.

[0009] These architectures can be based on a high bypass ratio and reducer type architecture, but also on multiple bodies (two or three). In these architectures, the turbomachine comprises a low pressure body and a high pressure body, each body comprising a shaft connecting a compressor rotor to a turbine rotor.

[0010] It is known to equip an aircraft turbomachine with an electric machine. It is recalled that an electric machine is an electromechanical device based on electromagnetism allowing the conversion of electrical energy, for example, into work or mechanical energy. This process is reversible and can be used to produce electricity.

[0011] Thus, depending on the final use of an electrical machine, we use the terms:

[0012] - generator to designate an electrical machine producing electrical energy from mechanical energy, - motor for an electrical machine producing mechanical energy from electrical energy.

[0013] An electric machine can also behave in motor mode according to a first operating phase and in generator mode according to a second operating phase distinct from the first.

[0014] Thus, the electrical machines in question here are electricity generators or reversible machines that can also work as an electric motor and which are then capable of starting a turbine or fan shaft or at least of providing it with additional power. They can complement the electricity generator usually found on the accessory gearbox (AGB) and which draws power from the high-pressure body if the electrical machine is integrated on the low-pressure body of a turbomachine.

[0015] Several installation areas are possible, but the advantages and disadvantages of each are numerous and varied (mechanical integration problems of the machine, temperature resistance of the machine, accessibility of the machine, etc.). For example, patent application FR 3 087 823 A1 describes the installation of an electric machine downstream of a blower. In addition, the electric machine can also be installed downstream of a turbine shaft and driven by this shaft.

[0016] The electrical machine has a generally annular shape and comprises a rotor and a stator. The rotor and stator each have a generally cylindrical shape extending around the axis of the turbomachine. The rotor generally comprises a disk and magnetic elements (e.g., permanent magnets) arranged regularly around the periphery of the disk, while the stator comprises a ring supporting coils distributed regularly in an annular manner inside the stator ring. The stator surrounds the rotor. In other words, the stator ring and the rotor disk are concentric, and the stator ring is radially outside the rotor disk. In other words, the coils are arranged radially outside the magnetic elements.

[0017] In nominal operation, two types of forces are applied to the rotor of an electrical machine: a torque (resistive or motor depending on the operating case), and a radial force.

[0018] In special operating cases, such as heavy operating loads, unbalance or other malfunctions, the rotor of the electric machine may be caused to move radially relative to the stator. For example, in the case of an electric machine arranged downstream of a fan, the rotor of the electric machine is fixed to a fan disc by means of a flange and screws. In the event of the loss of a blade from the fan disc, the disc becomes significantly unbalanced and begins to orbit under the effect of a significant unbalance. This imbalance can cause an eccentricity which in turn leads to the local closing of the air gap of the electric machine. Since the eccentricity linked to the loss of a blade is greatly greater than the clearance between the magnetic elements of the rotor and the coils of the stator of the electric machine, there is then contact between said magnetic elements and said coils of the electric machine.

[0019] Today, the air gap of an electrical machine is calculated to avoid any contact between the magnetic elements of the rotor and the stator coils. This imposes several constraints:

[0020] - either a large air gap to respond to significant maneuvering or failure cases,

[0021] - or the most complete mechanical decoupling possible between the electric machine and the rest of the turbomachine, which imposes integration constraints as described in patent FR 3 087 823.

[0022] However, a large air gap is detrimental to the performance of the electrical machine and mechanical decoupling imposes significant integration constraints (addition of decoupling elements, positioning of the assembly downstream of the turbomachine, etc.).

[0023] The objective of the present invention is to overcome at least some of the problems mentioned above. In particular, the present invention proposes a solution making it possible to eliminate the risk of contact between the magnetic elements of the rotor and the coils of the stator in order to avoid damaging the electrical machine or modifying the dynamic situation of the turbomachine, which ultimately allows a reduction in the air gap and a gain in performance.

[0024] SUMMARY OF THE INVENTION

[0025] To this end, the invention relates to a module for a turbomachine, in particular for an aircraft turbomachine, comprising a shaft extending in an axial direction and an electrical machine comprising:

[0026] - a rotor coupled in rotation with the shaft of the module, the rotor comprising a disc and magnetic elements arranged regularly around the periphery of the disc, and

[0027] - a stator secured to a casing of the module comprising a ring and coils distributed in an annular manner inside the ring of the stator, the coils are arranged outside the magnetic elements of the rotor in a radial direction, characterized in that each coil is movable radially between a first extreme position and a second extreme position, each coil being held in the first position in normal operation and moved towards the second extreme position in the event of movement of the rotor radially towards the stator coil.

[0028] The invention thus makes it possible to authorize the radial displacement of the elements carried by the stator of an electrical machine in order to reduce the air gap, to increase the performance of the electrical machine while being robust to the consumption of rotor / stator clearance. In other words, the invention makes it possible to eliminate the risk of contact between the magnetic elements of the rotor and the coils of the stator in order to avoid damaging the electrical machine or modifying the dynamic situation of the turbomachine.

[0029] In normal operation, the elements supported by the stator, i.e. the coils, are held in the extreme position, i.e. in a position in which all the elements supported by the stator are at the same distance from the rotor of the electric machine. In other words, the air gap of the electric machine is constant.

[0030] While in abnormal operation, for example under load factor, unbalance or other malfunction, the elements supported by the stator are pushed radially outwards by the rotor. The displacement of the elements supported by the stator radially outwards eliminates the risk of contact between the magnetic elements of the rotor and the stator coils. As a result, neither the electrical machine suffers any damage nor the dynamic situation of the turbomachine is modified.

[0031] Thus, the invention makes it possible to reduce the air gap of the electrical machine during normal operation, generating a gain in performance while remaining robust to particular operating cases such as high load factors. This gain in performance can result in a weight / size gain at equivalent power or a gain in power at equivalent mass.

[0032] In addition, the constraints of integrating the electric machine are reduced because it is no longer necessary to completely decouple the electric machine from the rest of the turbomachine or to position it in a position that is little impacted by load factors.

[0033] The module for a turbomachine according to the invention may comprise one or more of the following features, taken in isolation from one another or in combination with one another in all technically possible combinations: - the stator has an internal surface and supports return elements, each shaped to maintain an associated coil in the first position in normal operation, each return element being arranged between the internal surface of the stator and the associated coil;

[0034] - each return element is a spring or a blade of which a first end is connected to the internal surface of the stator and a second end opposite the first end is connected to the coil;

[0035] - the stator comprises for each coil at least one slide configured to guide the coil in rectilinear translation in a radial direction between the first and second extreme positions;

[0036] - each coil comprises two through holes each receiving a rod forming a slide, each rod having a circular section and extending substantially radially between a first end fixed to the internal surface of the stator and a second end shaped to form a stop for the coil in the first extreme position;

[0037] - each coil comprises a through-orifice receiving a rod forming a slide, the rod extending radially between a first end fixed to the internal surface of the stator and a second end shaped to form a stop for the coil in the first extreme position, the rod having a non-circular section, preferably rectangular or oblong;

[0038] - each coil is arranged in a gutter forming a slide, the gutter has a cylindrical body of complementary shape to the associated coil and shaped to guide the coil in rectilinear translation in the radial direction between the first and second extreme positions, the cylindrical body extending radially between a first end fixed to the internal surface of the stator and a second end shaped to form a stop for the coil in the first extreme position;

[0039] - the stator comprises, for each coil, an arm comprising a first end fixed to the coil and a second end connected to the internal surface of the stator by a pivot connection having a pivot axis extending perpendicular to the axial direction, the arm being shaped so that its pivoting causes the coil to move between the first extreme position and the second extreme position;

[0040] - the rotor comprises for each magnetic element at least one main contact element and the stator comprises for each coil at least one secondary contact element, each main contact element of the rotor being arranged opposite a secondary contact element of the stator, the main contact element and the secondary contact element being shaped to avoid contact between the coil of the stator and the magnetic element of the rotor in the event of movement of the rotor radially towards the coil of the stator;

[0041] - each primary contact element and each secondary contact element is made of bronze or non-stick polymer such as Teflon®;

[0042] - the air gap of the electrical machine defined by the distance in a radial direction between the magnetic elements and the coils in normal operation is between 0.5 mm and 10 mm.

[0043] The invention also relates to a turbomachine, in particular an aircraft turbomachine, comprising at least one module according to the invention and as described previously.

[0044] Preferably, the module is a blower module comprising a blower and the electric machine is mounted coaxially downstream of the blower, the rotor of the electric machine being rotationally coupled with the blower.

[0045] Alternatively, the module is a turbine module and the electric machine is mounted coaxially downstream of a turbine housing.

[0046] BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present invention will be better understood and other details, characteristics and advantages of the present invention will appear more clearly on reading the description of a non-limiting example which follows, with reference to the appended drawings in which:

[0048] - figure 1 is a schematic axial sectional view of an example of an aircraft turbomachine to which the invention applies, the example illustrated is a turbomachine with a high bypass ratio and reduction gear;

[0049] - figure 2 is a schematic view in longitudinal section of an electrical machine equipping a module according to the invention, according to a first embodiment and in normal operation;

[0050] - figure 3 represents a schematic cross-sectional view of the electrical machine of figure 2 in normal operation;

[0051] - Figure 4 is a schematic view of the section of an element supported by the stator of the electrical machine of Figures 2 and 3 in a plane perpendicular to the radial direction; - Figure 5 is a schematic view of the section of an element supported by the stator of the electrical machine of Figures 2 and 3 in a plane perpendicular to that of Figure 4;

[0052] - figure 6 is a schematic view in longitudinal section of the electric machine of figure 2 in abnormal operation, in which the rotor is eccentric;

[0053] - figure 7 is a schematic cross-sectional view of the electrical machine of figure 6 in abnormal operation;

[0054] - figure 8 is a schematic view in longitudinal section of an electrical machine equipping a module according to the invention, according to a second embodiment and in normal operation;

[0055] - figure 9 is a schematic view of the section of an element supported by the stator of the electrical machine of figure 8 in a plane perpendicular to the radial direction;

[0056] - figure 10 is a schematic view of a variant of the section of an element supported by the stator of the electrical machine of figure 8 in a plane perpendicular to the radial direction;

[0057] - figure 11 is a schematic view of the section of an element supported by the stator of the electrical machine of figure 8 in a plane perpendicular to that of figures 9 and 10;

[0058] - figure 12 is a schematic view in longitudinal section of the electric machine of figure 8 in abnormal operation;

[0059] - figure 13 is a schematic view in longitudinal section of an electrical machine equipping a module according to the invention, according to a third embodiment and in normal operation;

[0060] - figure 14 is a schematic longitudinal sectional view of the electrical machine of figure 13 in abnormal operation.;

[0061] - figure 15 is a schematic view in longitudinal section of an electrical machine equipping a module according to the invention, according to a fourth embodiment and in normal operation; and

[0062] - figure 16 is a schematic longitudinal sectional view of the electric machine of figure 15 in abnormal operation.

[0063] Elements having the same functions in different implementations have the same references in the figures.

[0064] DESCRIPTION OF THE EMBODIMENTS We first refer to Figure 1 which schematically represents a twin-spool, twin-flow aircraft turbomachine 10 to which the invention applies. Of course, the invention can be applied to other types of turbomachine equipped with an electric machine, for example a turboprop, without departing from the scope of the invention.

[0065] The turbomachine 10 has a longitudinal axis denoted C around which its various components extend.

[0066] The turbomachine 10 conventionally comprises a gas generator 12 upstream of which a fan 14 is arranged. The fan 14 is surrounded by a fan casing 16 which is surrounded by a nacelle 18 which extends around and along a major part of the gas generator 12.

[0067] The gas generator 12 here comprises two bodies, namely a low pressure body 12a or LP and a high pressure body 12b or HP. Each body comprises a compressor and a turbine.

[0068] In the present invention, and in general, the terms "upstream" and "downstream" are defined with respect to a main direction F of circulation of the fluids inside the turbomachine, and here along the longitudinal axis C, that is to say from left to right with reference to figure 1.

[0069] From upstream to downstream, the gas generator 12 comprises 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.

[0070] The longitudinal axis C is the axis of rotation of the moving elements of the turbomachine 10, and in particular, of the turbines 26, 28.

[0071] The fan 14 comprises an annular row of blades 30 driven in rotation by a fan shaft 32 which is connected to the rotor of the low-pressure body 12a via a reducer 33. The gas flow which passes through the fan (arrow F) is separated upstream of the gas generator 12 by an annular nozzle 34 into a radially internal annular flow, called primary flow 36 which feeds the gas generator 12, and into a radially external annular flow, called secondary flow 38 which flows between the gas generator 12 and the nacelle 18 and provides the majority of the thrust of the turbomachine.

[0072] An inlet casing 40 structurally connects the gas generator 12 to the fan casing 16 and to the nacelle 18. The inlet casing 40 comprises an annular row of radially inner arms 42 extending into the primary flow 36, and an annular row of radially outer rectifier vanes 44 (OGV type) extending into the secondary flow 38. The arms 42 are generally limited in number (less than ten) and are tubular and crossed by ancillaries. The number of vanes 44 (OGV) is generally greater than ten.

[0073] The turbomachine comprises a module 100 according to the invention comprising a shaft extending in an axial direction A, parallel to the longitudinal axis of the turbomachine and an electric machine 110.

[0074] Zone Z1 represents an area located between the fan disc 32 and the reducer 33, in which the electric machine can be installed.

[0075] Zone Z2 represents another zone located downstream of the low pressure turbine 28 in which the electric machine can also be installed.

[0076] In the description, the expressions "internal" or "interior" and "external" or "exterior" are used without limitation in reference to the radial distance from the longitudinal axis C around which the turbomachine extends, the expression "internal" defining a zone radially closer to the longitudinal axis of the nacelle, as opposed to the expression "external". Furthermore, in the description and the claims, the terminology axial, radial and transverse will be adopted without limitation in reference to the trihedron A, R, T indicated in the figures, the axial axis A being parallel to the longitudinal axis of the turbomachine.

[0077] With reference to figures 2 to 7 and 10 to 12, the electrical machine 110 has a generally annular shape and comprises a rotor 120 and a stator 130.

[0078] The rotor 120 has a generally cylindrical shape extending circumferentially around an axis of rotation coincident with the axis C of the turbomachine. The rotor is coupled with the shaft of the module 100, that is to say the shaft of the fan if the electric machine is installed downstream of the fan (Zone Z1) or the shaft of the low-pressure turbine if the electric machine is installed downstream of the latter (Zone Z2).

[0079] The rotor 120 comprises an annular disc 122 and magnetic elements 124 arranged regularly around the periphery of the disc 122. The magnetic elements 124 are, for example, permanent magnets.

[0080] In the examples illustrated in Figures 2 to 7 and 10 to 12, the disk 122 has an upstream circumferential edge 126 called the “upstream edge” and a downstream circumferential edge 128 called the “downstream edge”. The upstream 126 and downstream 128 edges extend from a circumferential bottom 129 of the disk radially outwards. The magnetic elements 124 are in contact with the circumferential bottom 129 of the disk. More precisely, the magnetic elements 124 are radially outwards relative to the circumferential bottom 129 supporting the magnetic elements 124.

[0081] In addition, the magnetic elements 124 are arranged between the upstream 126 and downstream 128 edges of the disc 122 of the rotor 120.

[0082] Generally, the magnetic elements 124 are shrunk onto the disc 122 of the rotor 120.

[0083] The stator 130 comprises a ring also having a generally cylindrical shape extending circumferentially around the axis C of the module and the turbomachine. The stator 130 is integral with a casing of the module, for example the fan casing 16 (zone Z1).

[0084] The stator ring 130 has an inner surface 132, i.e. a radially inner surface.

[0085] The stator ring 130 supports coils 134 distributed in an annular manner within the ring.

[0086] The stator surrounds the rotor. In other words, the stator ring and the rotor disc are concentric and the stator ring is radially outside the rotor disc. The coils 134 are arranged facing the magnetic elements 124 of the rotor 120 in a radial direction R. In other words, the magnetic elements 124 of the rotor 120 are radially inside the coils 134 of the stator 130.

[0087] Each coil 134 has a radially inner surface 136 called the “inner surface” and a radially outer surface 137 called the “outer surface”.

[0088] Each coil 134 is formed of a conductive wire wound around a support, the support being fixed to the stator ring 130.

[0089] According to the invention, each coil 134 is radially movable between a first extreme position and a second extreme position. Each coil 134 is held in the first position during normal operation and moved to the second extreme position in the event of movement of the rotor 120 radially towards the coil 134 of the stator 130. The second extreme position is thus radially outward relative to the first extreme position.

[0090] According to the invention, the air gap of the electrical machine defined by the distance in a radial direction between the magnetic elements and the coils in normal operation is between 0.5 mm and 10 mm. Figures 2 to 7 refer to a first embodiment of a module according to the invention.

[0091] According to this first embodiment, the stator comprises, for each coil, at least one slide configured to guide the coil in rectilinear translation in the radial direction R between the first and second extreme positions.

[0092] More specifically, according to this first embodiment, the stator 130 comprises, for each coil 134, two slides configured to guide the coil in rectilinear translation along the radial direction R between the first and second extreme positions. Figures 2 and 3 illustrate the electrical machine in normal operation, that is to say when the rotor 120 does not undergo any radial displacement due for example to unbalances. In this case, the coils 134 of the stator 130 are in their first position. More specifically, they are held in the first extreme position in normal operation by return elements. Each return element is supported by the internal surface 132 of the stator 130, more precisely by the internal surface 132 of the ring of the stator 130. Each return element is arranged between the internal surface 132 of the stator 130 and the associated coil 134 so as to return the coil to the first extreme position.

[0093] In the illustrated example, the return element is a return spring 140 of which a first end 142 is connected to the stator 130 and a second end 144 opposite the first end 142 is connected to the radially outer surface 137 of the coil, more precisely to the radially outer surface of the support around which the conductive wire is wound. In normal operation, the spring 140 is stressed in order to maintain the coil 134 in the first extreme position, that is to say in a position distant from the internal surface 132 of the stator in a radial direction R. The radial stiffness of the springs 140 must be adapted to be as low as possible, in order not to influence the dynamic situation and limit the contact forces, while preserving the support of the elements under the various loads (vibration, operating loads) and with respect to the electromagnetic radial resultant.

[0094] In the illustrated example, the return element is a spring 140. Alternatively, the return element may be a strip of which a first end is connected to the stator and a second end opposite the first end is connected to the coil and shaped to hold the coil in the first extreme position.

[0095] Furthermore, each coil 134 has two through holes 150. More specifically, each hole 150 is provided in the support of the coil 134. Each through hole 150 receives a rod 160 forming a slide. Each rod 160 extends substantially radially between a first end 162 fixed to the stator 130 and a second end 164 opposite the first end 162. The second end 164 is shaped to form a stop 166 for the coil 134 in the first extreme position.

[0096] With reference to Figure 4, which illustrates a sectional view along plane AA (visible in Figure 2) of the stator, and in particular of a coil 134, in a plane perpendicular to the radial axis R, each rod 160 has a circular section. The two rods 160 are arranged in the same plane perpendicular to the axis T, i.e. extending along the axial A and radial R directions.

[0097] Figure 5 represents a sectional view along plane BB (visible in Figures 3 and 4) of the stator 130. Each rod 160 has a second end 164 having a protuberance 167 of diameter greater than that of the rod at the first end 162 in order to form a stop 166 for the coil.

[0098] In the example illustrated in Figure 2, the protrusion 167 is in contact with the inner surface 136 of the coil 134. Alternatively, the coil 134 may comprise two recesses 168 (visible in Figure 5) each configured to receive the protrusion of a rod such that the protrusion 167 is in contact with a bottom of a recess 168 and the protrusion is entirely housed in the recess 168 such that the protrusion does not protrude inwardly beyond the inner surface of the coil. This feature advantageously makes it possible to avoid possible contact with a magnetic element of the rotor and therefore possible damage to the latter even in normal operation.

[0099] In this embodiment, the stator 130 comprises two slides per coil in order to prevent any rotation of the latter around a radial axis.

[0100] Furthermore, in order to guarantee the absence of contact between the magnetic elements 124 of the rotor 120 and the elements supported by the stator 130, the coils 134 in the illustrated example, the rotor 120 advantageously comprises for each magnetic element 124 at least one main contact element 170 and the stator 130 also comprises for each element supported by the stator, the coils 134 in the illustrated example, at least one secondary contact element 180. Each main contact element 170 of the rotor 120 is arranged opposite a secondary contact element 180 of the stator 130. The main contact element 170 and the secondary contact element 180 are shaped to avoid contact between the coil 134 of the stator 130 and the magnetic element 124 of the rotor 120 in the event of displacement of the rotor radially towards the coil of the stator. (figures 6 and 7).

[0101] Figures 6 and 7 illustrate the electrical machine in abnormal operation, that is to say when the rotor 120 undergoes a radial displacement, shown diagrammatically by the arrow F1, due for example to unbalances. In this case, the coils 134 of the stator towards which the rotor moves, are displaced radially outwards according to the arrow F2 towards their second extreme position as soon as associated main contact elements 170 of the rotor 120 are in contact with corresponding secondary contact elements 180 of the stator 130. The return element, the spring 140 in the illustrated example, is even more stressed, here compressed.

[0102] The displacement of the elements supported by the stator, the coils 134 in the illustrated example, radially outwards following the contact of the main contact elements 170 of the rotor with the corresponding secondary contact elements 180 of the stator 130 makes it possible to eliminate any contact between the magnetic elements 124 of the rotor and the coils 134 of the stator. As a result, neither the electrical machine suffers any degradation nor the dynamic situation of the turbomachine is modified.

[0103] In the embodiment illustrated in Figures 2 to 7, a first main contact element 170 called “upstream main contact element” is supported by a radially outer surface of the upstream edge 126 of the disc 122 of the rotor and a second main contact element 170 called “downstream main contact element” is supported by a radially outer surface of the downstream edge 128 of the disc 122 of the rotor.

[0104] Similarly, a first secondary contact element 180 called “upstream secondary contact element” is supported by an upstream edge 138 of the radially inner surface 136 of the support of the coil 134 of the rotor and a second secondary contact element 180 called “downstream secondary contact element” is supported by a downstream edge 139 of the support of the radially inner surface 136 of the coil 134 of the rotor 130.

[0105] Preferably, each primary contact element 170 and each secondary contact element 180 is made of a low-friction material, preferably bronze or a non-stick polymer such as Teflon® in order to limit heating and damage. In addition, the primary contact elements may be shrink-fitted, screwed, or glued to the rotor disc 122. Similarly, the secondary contact elements may be attached to the coil support by shrink-fitting, screwing, or gluing.

[0106] Thus, in abnormal operation, the upstream main contact element 170 is in contact with the upstream secondary contact element 180 and the downstream main contact element 170 is in contact with the downstream secondary contact element 180, avoiding any direct contact between the coils 134 and the magnetic elements 124 which could have damaged them.

[0107] Figures 8 to 11 represent a second embodiment which differs from the first in that the stator 130 comprises a single slide for each coil 134, the slide being configured to guide the coil in rectilinear translation in a radial direction between the first and second extreme positions.

[0108] Figure 8 illustrates the electrical machine in normal operation, that is to say when the rotor is not subject to any radial displacement due for example to unbalances. In this case, the coils 134 of the stator are in their first position. As for the first embodiment, the coils are held in the first extreme position in normal operation by return elements.

[0109] In the illustrated example, the return element is a spring 140. However, the return element may be an elastic strip as for the first embodiment.

[0110] Each coil 134 has a single through-hole 150 receiving a rod 160 forming a slide. More precisely, the single orifice 150 is provided in the coil support around which the conductive wire is wound. The rod 160 extends substantially radially between a first end 162 fixed to the stator 130 and a second end 164 opposite the first end 162. The second end 164 is shaped to form a stop 166 for the coil 134 in the first extreme position.

[0111] In order to avoid rotation of the coil 134 around the axis of the rod 160, the rod 160 has a non-circular section. In particular, the rod 160 has a rectangular section as illustrated in FIG. 9 or an oblong section as illustrated in FIG. 10. FIGS. 9 and 10 illustrate a sectional view along the plane AA (visible in FIG. 8) of the stator, and in particular of a coil 134, in a plane perpendicular to the radial axis R.

[0112] Figure 11 represents a sectional view along plane BB (visible in Figures 9 and 10) of the stator 130. As for the first embodiment, the rod 160 has a second end 164 having a protuberance 167 of diameter greater than that of the rod at the first end 162 in order to form a stop 166 for the coil.

[0113] In the example illustrated in Figure 8, the protrusion 167 is in contact with the inner surface 136 of the coil 134. Alternatively, the coil 134 may comprise a recess 168 (visible in Figure 11) configured to receive the protrusion of the rod such that the protrusion 167 is in contact with a bottom of a recess 168 and the protrusion is entirely housed in the recess 168 such that the protrusion does not protrude inwardly beyond the inner surface of the coil. This feature advantageously makes it possible to avoid possible contact with a magnetic element of the rotor and therefore possible damage to the latter even during abnormal operation.

[0114] In a similar manner to the first embodiment, in order to guarantee the absence of contact between the magnetic elements 124 of the rotor 120 with the elements supported by the stator 130, the coils 134 in the illustrated example, the rotor 120 advantageously comprises for each magnetic element 124 at least one main contact element 170 and the stator 130 also comprises for each element supported by the stator, the coils 134 in the illustrated example, at least one secondary contact element 180. The description of these elements for the first embodiment also applies to the second embodiment.

[0115] Thus, in abnormal operation (figure 12), the upstream main contact element 170 is in contact with the upstream secondary contact element 180 and the downstream main contact element 170 is in contact with the downstream secondary contact element 180, avoiding any direct contact between the coils 134 and the magnetic elements 124 which could have damaged them.

[0116] Figure 12 illustrates the electrical machine in abnormal operation, that is to say when the rotor 120 undergoes a radial displacement, shown diagrammatically by the arrow F1, due for example to unbalances. In this case, the coils 134 of the stator towards which the rotor moves, are displaced radially outwards according to the arrow F2 towards their second extreme position as soon as associated main contact elements 170 of the rotor 120 are in contact with corresponding secondary contact elements 180 of the stator 130. The return element, the spring 140 in the illustrated example, is even more stressed, here compressed.

[0117] The displacement of the elements supported by the stator, the coils 134 in the illustrated example, radially outwards following the contact of the main contact elements 170 of the rotor with the corresponding secondary contact elements 180 of the stator 130 makes it possible to eliminate any contact between the magnetic elements 124 of the rotor and the coils 134 of the stator. As a result, neither the electrical machine suffers any degradation nor the dynamic situation of the turbomachine is modified.

[0118] Figures 13 and 14 represent a third embodiment which differs from the first in that the stator 130 comprises a single slide for each coil 134, the slide being configured to guide the coil in rectilinear translation in a radial direction between the first and second extreme positions.

[0119] In this third embodiment, each slide associated with a coil is formed by a gutter 190 housing said coil. The gutter 190 is shaped to guide the coil in rectilinear translation in a radial direction between the first and second extreme positions. For this purpose, the gutter 190 comprises a cylindrical body 191 with a main axis denoted E and a shape complementary to the associated coil 134 and shaped to guide the coil in rectilinear translation in the radial direction between the first and second extreme positions. The cylindrical body 191 extends radially between a first end 192 fixed to the stator 130 and a second end 194 shaped to form a stop 196 for the coil 134 in the first extreme position.

[0120] In the example illustrated in Figures 13 and 14, the second end 192 of the cylindrical body 191 has a protrusion 197 extending from an internal surface of the cylindrical body 191 towards the inside thereof, that is to say towards the main axis E of the cylindrical body. The protrusion extends over the entire internal circumference of the second end 192 of the cylindrical body 191 as far as one or more free edges 198 depending on the shape of the protrusion. The protrusion extends continuously or in regularly distributed portions over this entire circumference. As a result, the protrusion is shaped to retain the coil 134 in the cylindrical body in the first extreme position. In other words, the internal dimension D1 of the protuberance, that is to say the dimension in the axial direction between the free edges 198 of the protuberance 197 is less than the dimension D2 of the coil in the same axial direction.In the illustrated example, dimension D2 is the dimension of the coil support 134 which is wider than the wound portion of the coil.

[0121] As for the first and second embodiments, in order to guarantee the absence of contact between the magnetic elements 124 of the rotor 120 with the elements supported by the stator 130, the coils 134 in the illustrated example, the rotor 120 advantageously comprises for each magnetic element 124 at least one main contact element 170 and the stator 130 also comprises for each element supported by the stator, the coils 134 in the illustrated example, at least one secondary contact element 180. The description of these elements for the first embodiment also applies to the third embodiment.

[0122] Thus, in abnormal operation illustrated in Figure 14, following the movement of the rotor towards the stator, the upstream main contact element 170 is in contact with the upstream secondary contact element 180 and the downstream main contact element 170 is in contact with the downstream secondary contact element 180, avoiding any direct contact between the coils 134 and the magnetic elements 124 which could have damaged them.

[0123] Figures 15 and 16 show a fourth embodiment in which the stator 130 comprises, for each coil 134, an arm 210 comprising a first end 212 fixed to the coil 134 and a second end 214 connected to the stator by a pivot connection 215. The pivot connection 215 has a pivot axis denoted F extending perpendicular to the axial direction A and to the radial direction R. The arm 210 is shaped so that its pivoting causes the coil to move between the first extreme position and the second extreme position.

[0124] In the illustrated example, the pivot link 215 is arranged upstream of the coil. However, it can be arranged downstream of it.

[0125] Indeed, the arm 210 is configured to pivot around the pivot axis F between a first position corresponding to the first extreme position of the coil 134 and a second position corresponding to the second extreme position of the coil 134.

[0126] Thus, the stator 130 further comprises a rod 220 extending radially between a first end 222 fixed to the internal surface 132 of the stator 130 and a second end 224 shaped to form a stop 226 for the arm 210 in the first position.

[0127] For example, the arm 210 has a through hole at its second end 214 receiving the rod 220 and the second end 224 of the rod 220 has a protrusion 227 of diameter / dimension greater than that of the rod at its first end 222 in order to form a stop 226 for the arm 210.

[0128] Figure 15 illustrates the electrical machine in normal operation, that is to say when the rotor is not subject to any radial displacement due for example to unbalances. In this case, the stator coils are in their first extreme position. More precisely, they are held in the first extreme position in normal operation by return elements. Each return element is supported by the internal surface 132 of the stator 130. Each return element is arranged between the internal surface 132 of the stator 130 and the associated coil 134 so as to hold the coil in the first extreme position.

[0129] In the illustrated example, the return element is a strip 240 of which a first end 242 is connected to the stator 130 and a second end 244 opposite the first end is connected to the coil 134 and shaped to return the coil to the first extreme position.

[0130] However, alternatively, the return element may be a return spring having a first end connected to the stator and a second end opposite the first end connected to the radially outer surface of the coil to return the coil to its first extreme position.

[0131] Furthermore, in order to guarantee the absence of contact between the magnetic elements 124 of the rotor 120 and the elements supported by the stator 130, the coils 134 in the illustrated example, the rotor 120 advantageously comprises for each magnetic element 124 at least one main contact element 170 and the stator 130 also comprises for each element supported by the stator, the coils 134 in the illustrated example, at least one secondary contact element 180. Each main contact element 170 of the rotor 120 is arranged opposite a secondary contact element 180 of the stator 130. The main contact element 170 and the secondary contact element 180 are shaped to avoid contact between the coil 134 of the stator 130 and the magnetic element 124 of the rotor 120 in the event of displacement of the rotor radially towards the coil of the stator. (figure 16).

[0132] Figure 16 illustrates the electrical machine in abnormal operation, that is to say when the rotor undergoes a radial displacement, shown diagrammatically by the arrow F1, due for example to unbalances. In this case, the coils 134 of the stator towards which the rotor moves, are displaced radially outwards according to the arrow towards their second extreme position as soon as associated main contact elements 170 of the rotor 120 are in contact with corresponding secondary contact elements 180 of the stator 130. The return element, the blade 240 in the illustrated example, is even more stressed than in the first extreme position (figure 14).

[0133] More specifically, the coils 134 of the stator towards which the rotor moves, are pivoted about the pivot axis F causing a radial outward movement of said coils.

[0134] The displacement of the elements supported by the stator, the coils 134 in the illustrated example, radially outwards, following the contact of the main contact elements 170 of the rotor with the corresponding secondary contact elements 180 of the stator 130, makes it possible to significantly reduce or even eliminate any risk of contact between the magnetic elements 124 of the rotor and the coils 134 of the stator. As a result, neither the electrical machine suffers any degradation nor the dynamic situation of the turbomachine is modified.

[0135] In the embodiment illustrated in Figures 15 and 16, a main contact element 170 called “downstream main contact element” is supported by a radially outer surface of the downstream edge 128 of the disc 122 of the rotor.

[0136] Similarly, a secondary contact element 180 called “downstream secondary contact element” is supported by a downstream edge 139 of the radially inner surface 136 of the coil 134 of the rotor 130.

[0137] Preferably, each main contact element 170 and each secondary contact element 180 is made of a low friction material, preferably bronze or a non-stick polymer such as Teflon® in order to limit heating and damage.

[0138] In addition, the primary contact elements may be shrink-fitted, screwed, or glued to the rotor disc 122. Similarly, the secondary contact elements may be attached to the coil support by shrink-fitting, screwing, or gluing.

[0139] The invention as described above thus allows the radial displacement of the elements supported by the stator of an electrical machine in order to reduce the air gap, increase performance while being robust to rotor / stator clearance consumption.

[0140] Indeed, the inventors estimated that the invention allows a 20% reduction in the air gap compared to an electrical machine of the prior art, thus allowing a gain of approximately 5% in mass of the electrical machine at equivalent power.

Claims

CLAIMS 1. Module (100) for a turbomachine, in particular for an aircraft turbomachine, comprising a shaft extending in an axial direction and an electric machine (110) comprising: - a rotor (120) coupled in rotation with the shaft of the module, the rotor comprising a disc (122) and magnetic elements (124) arranged regularly on the periphery of the disc, and - a stator (130) secured to a casing of the module comprising a ring and coils (134) distributed in an annular manner inside the ring of the stator, the coils are arranged outside the magnetic elements of the rotor in a radial direction, characterized in that each coil is movable radially between a first extreme position and a second extreme position, each coil being held in the first position in normal operation and moved towards the second extreme position in the event of movement of the rotor radially towards the stator coil.

2. Module according to claim 1, in which the stator (130) has an internal surface (132) and supports return elements (140, 240), each shaped to maintain an associated coil (134) in the first position in normal operation, each return element (140, 240) being arranged between the internal surface (132) of the stator and the associated coil.

3. Module according to claim 2, in which each return element is a spring (140) or a blade (240) of which a first end is connected to the internal surface (132) of the stator and a second end opposite the first end is connected to the coil.

4. Module according to one of claims 1 to 3, in which the stator (130) comprises for each coil (134) at least one slide configured to guide the coil in rectilinear translation in a radial direction between the first and second extreme positions.

5. Module according to claim 4, in which each coil comprises two through orifices (150) each receiving a rod (160) forming a slide, each rod (160) having a circular section and extending substantially radially between a first end (162) fixed to the internal surface (132) of the stator (130) and a second end (164) shaped to form a stop (166) for the coil (134) in the first extreme position.

6. Module according to claim 4, in which each coil (134) comprises a through orifice (150) receiving a rod (160) forming a slide, the rod extending radially between a first end (162) fixed to the internal surface (132) of the stator (130) and a second end (164) shaped to form a stop (166) for the coil (134) in the first extreme position, the rod having a non-circular section, preferably rectangular or oblong.

7. Module according to claim 4, in which each coil (134) is arranged in a gutter (190) forming a slide, the gutter has a cylindrical body (191) of a shape complementary to the associated coil and shaped to guide the coil in rectilinear translation in the radial direction between the first and second extreme positions, the cylindrical body extending radially between a first end (192) fixed to the internal surface (132) of the stator and a second end (194) shaped to form a stop (196) for the coil in the first extreme position.

8. Module according to one of claims 1 to 3, in which the stator (130) comprises, for each coil (134), an arm (210) comprising a first end (212) fixed to the coil (134) and a second end (214) connected to the internal surface (132) of the stator by a pivot connection (215) having a pivot axis (F) extending perpendicular to the axial direction (A), the arm (210) being shaped so that its pivoting causes the coil (134) to move between the first extreme position and the second extreme position.

9. Module according to one of the preceding claims, in which the rotor comprises for each magnetic element at least one main contact element (170) and the stator (130) comprises for each coil (134) at least one secondary contact element (180), each main contact element of the rotor being arranged opposite a secondary contact element of the stator, the main contact element and the secondary contact element being shaped to avoid contact between the stator coil and the magnetic element of the rotor when the rotor moves radially towards the stator coil.

10. Turbomachine, in particular aircraft turbomachine, comprising at least one module according to one of the preceding claims.

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