TURBOMACHINE MODULE EQUIPPED WITH AN ELECTRIC ENGINE

Abstract

The invention relates to a module for a turbomachine comprising a shaft in an axial direction and an electric machine (110) comprising: - a rotor (120) coupled in rotation with the shaft and comprising a disk (122) and magnetic elements (124) arranged regularly around the periphery of the disk, and - a stator (130) integral with a housing of the module comprising a ring (132) and coils distributed annularly inside the ring of the stator, the coils are arranged outside the magnetic elements of the rotor in a radial direction, wherein the rotor has an imbalance defect represented by a mechanical force (F1) when the magnetic elements are in a first position, and at least one magnetic element (124) is movable from the first position to a second position adapted to apply to the rotor a magnetic force (F2) opposite to the mechanical force when the electric machine is in operation.Figure for the abbreviation: Figure 2.

Description

Title of the invention: TURBOMACHINE MODULE EQUIPPED WITH AN ELECTRIC MACHINE technical field

[0001] The technical field of the invention is that of turbomachines equipped with an electric machine.

[0002] The present invention relates in particular to an aircraft turbomachine module equipped with an electric machine. Previous technique

[0003] The aeronautical world is currently asking itself many questions regarding the relevance of using hybrid engines for commercial aviation. The use of electrical energy is now being considered not only to fulfill aircraft functions but also to electrify turbomachine functions.

[0004] This observation leads to the study of hybrid engine architecture solutions, combining the fossil energy of the fuel and the electrical energy to ensure the drive of the propulsion part (fan or turbine of the turbomachine) and the supply of certain engine and / or aircraft functions.

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

[0006] It is known to equip an aircraft turbomachine with an electric machine. An electric machine is an electromechanical device based on electromagnetism that converts electrical energy, for example, into work or mechanical energy. This process is reversible and can be used to produce electricity.

[0007] Thus, depending on the end use of an electrical machine, the following terms are used: - generator to designate an electrical machine that produces electrical energy from mechanical energy, - motor for an electrical machine producing mechanical energy from electrical energy.

[0008] An electrical machine can also behave in motor mode according to a first phase of operation and in generator mode according to a second phase of operation distinct from the first.

[0009] Thus, the electrical machines referred to here are electricity generators or reversible machines that can also operate as electric motors and are therefore capable of starting a turbine or blower shaft, or at least providing it with additional power. They can supplement the electricity generator usually found on the accessory gearbox (AGB), which draws power from the high-pressure casing if the electric machine is integrated into the low-pressure casing of a turbomachine.

[0010] Several installation locations are possible, but the advantages and disadvantages of each are numerous and varied (problems of mechanical integration of the machine, machine temperature resistance, machine accessibility, etc.). For example, French patent application FR 3 087 823 A1 describes the installation of an electric machine downstream of a blower. Furthermore, the electric machine can also be installed downstream of a turbine shaft and driven by that shaft.

[0011] The electric 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 (for example, permanent magnets) arranged regularly around the periphery of the disk, while the stator comprises a ring supporting coils distributed regularly in an annular pattern 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 external to the rotor disk. The coils are arranged radially external to the magnetic elements.

[0012] Parts rotating around an axis of rotation, such as the rotors of a compressor, turbine, or electrical machine, generally exhibit, as a result of their manufacture, a balancing defect called unbalance, which is due to a misalignment of the part's axis of rotation with its axis of inertia. This misalignment leads to the appearance of mechanical stresses that can damage the equipment in which the rotating parts are located, and cause vibrations and / or noise.

[0013] These eccentricity defects are of static or dynamic origin. Static eccentricity is linked to assembly defects (assembly between parts), while dynamic eccentricity is a defect that commonly appears in overall dynamics. It is linked to the presence of mechanical imbalance. More specifically, a commonly encountered static imbalance is one in which the axis of inertia of the part is parallel to, but distinct from, its axis of rotation. Another known balancing defect is the unbalanced couple (also called torque imbalance), in which the center of gravity is located on The axis of rotation is parallel to the axis of inertia, but the axis of inertia forms a non-zero angle with it. The combination of a static imbalance and an unbalanced moment is called a dynamic imbalance. However, the unbalanced moment is negligible when the diameter of the part is large relative to its length, and the dynamic imbalance is equivalent to the static imbalance.

[0014] In the specific case of an electric machine rotor, these defects modify the air gap width and consequently the permeance of the magnetic circuit. The electromagnetic efficiency of the machine is therefore locally greater and creates a radial restoring force oriented along the azimuth of the air gap closure. This is therefore a so-called magnetic unbalance force that is added to the existing mechanical unbalance and is the origin of the initial eccentricity.

[0015] To correct mechanical imbalance, current manufacturing processes include a balancing step, in which mass is added to or removed from the part, particularly a rotor, so as to bring the axis of inertia closer to the axis of rotation. More precisely, mass is added to the rotating part or the rotor at the axial position closest to the imbalance defect to be corrected and at the azimuth opposite to the identified defect. This traditional balancing requires a position for adding mass with a flange having a fairly fine angular discretization. Furthermore, it is also necessary to define the components that allow the mass addition: screws, nuts, counterweights, clips, etc., which are dedicated to balancing the rotating part but significantly increase the mass of the turbomachine in question.

[0016] The objective of the present invention is to overcome at least some of the problems mentioned above. In particular, the present invention provides a solution for balancing a turbomachine rotor comprising an electric machine without adding extra mass that could degrade the turbomachine's performance. Summary of the invention

[0017] To this end, the invention relates to a module for a turbomachine, in particular for an aircraft turbomachine, comprising a shaft extending along an axial direction and an electric machine comprising: - a rotor coupled in rotation with the module shaft, the rotor comprising a disk and magnetic elements arranged regularly around the periphery of the disk, and - a stator attached to a module housing comprising a ring and coils distributed in an annular manner inside the stator ring, the coils are arranged outside the magnetic elements of the rotor in a radial direction. According to the invention, the rotor exhibits a balancing defect represented by a mechanical force when the magnetic elements are in a first position, and at less a magnetic element is mobile from the first position to a second position suitable for applying to the rotor a magnetic force opposite to the mechanical force when the electric machine is in operation.

[0018] A rotor is defined as a part that can be rotated, via a magnetic field, by an electrically rotating machine comprising a stator. The rotor is held and guided in rotation by bearings, for example of the roller type.

[0019] Thus, the invention proposes to exploit the electric machine installed in the tur-bomachine for hybridization problems in order to achieve the balancing of a rotor of the turbomachine.

[0020] More specifically, the invention proposes to move the magnets of the electric machine's rotor primarily radially in order to balance the rotor through mechanical effect, but also by exploiting the magnetic imbalance effect. Since the radial movement of the magnets is limited by the available air gap between the rotor and the stator of the electric machine, the invention takes advantage of the magnetic imbalance created to achieve the required balancing force. Indeed, the radial movement of the magnets already present to balance the rotor generates a magnetic imbalance that complements the mechanical imbalance due to the movement of the magnets. Thus, the mechanical effect usually used to balance the rotor is supplemented or even replaced by the magnetic effect.This allows the functions of the different components of the turbomachine to be shared and increases the balancing capacity, and in some cases even makes it possible to perform balancing in an inaccessible area for the addition of extra mass according to the prior art.

[0021] The invention thus makes it possible to balance a turbomachine rotor comprising an electric machine by taking advantage of the parts already available in the turbomachine and consequently without adding additional mass which could degrade the performance of the turbomachine.

[0022] The module for a turbomachine according to the invention may comprise one or more of the following features, taken individually or in combination with each other in all technically possible combinations: - each magnetic element is radially mobile between the first position and the second position and the magnetic elements are radially abutted against the rotor disc in the first position; - the rotor includes radial adjustment devices, each associated with a magnetic element and adapted to adjust the distance between the rotor disk and the magnetic element in an outward radial direction according to the magnetic force to be applied to the rotor; - Each radial adjustment device includes a screw having a first end fixed to the associated magnetic element and a second end connected to the rotor disc and adapted so that a rotation of the screw causes a radial displacement of the associated magnetic element; - Each radial adjustment device includes: — at least one elastic strip arranged between the associated magnetic element and the rotor disc, — a first fixed inclined plane arranged between the stator and the rotor disc and in contact with a first tangential end of the magnetic element, — a second movable inclined plane arranged between the stator and the rotor disk and in contact with a second tangential end of the magnetic element opposite to the first tangential end, the second inclined plane being movable in translation along a tangential direction perpendicular to the radial direction and the inclined planes and the magnetic element are configured to cooperate so that a translation of the second inclined plane causes a radial displacement of the associated magnetic element; - the rotor is mobile in translation so as to collectively move the magnetic elements to a second position adapted to apply to the rotor a magnetic force opposite to the mechanical force when the electric machine is in operation.

[0023] The invention also relates to a turbomachine, in particular an aircraft turbomachine, comprising at least one module according to the invention and as described above.

[0024] Preferably, the module is a blower module comprising a blower and the electric machine is mounted coaxially with the axis of the blower and downstream of the blower, the rotor of the electric machine being coupled in rotation with the blower.

[0025] Alternatively, the module is a turbine module and the electric machine is mounted coaxially with the turbine module and downstream of a turbine housing.

[0026] According to another embodiment, the electric machine is integrated into the core of the turbomachine. For example, it is mounted on the high-pressure body of the turbomachine.

[0027] The invention also relates to a method for balancing a rotor of a module according to the invention, comprising at least the following steps: - determine the mechanical force representative of the imbalance defect; - determine the displacement of at least one magnetic element to be moved to balance the rotor as a function of the determined mechanical force; - move at least one magnetic element to be moved by the determined displacement in order to balance the rotor.

[0028] According to one embodiment, the step of determining the displacement of at least one The magnetic element to be moved includes at least the following steps: - determine at least one magnetic element to be moved to balance the rotor according to the determined mechanical force; and - for each magnetic element to be moved determined, determine the distance of displacement of the magnetic element as a function of the determined mechanical force. Brief description of the drawings

[0029] The present invention will be better understood and other details, features and advantages of the present invention will become more apparent upon reading the description of a non-limiting example that follows, with reference to the accompanying drawings in which: - [Fig.1] is a schematic axial cross-sectional view of an example of an aircraft turbomachine to which the invention applies; the example illustrated is a high bypass ratio turbomachine and reducer; - [Fig.2] is a schematic cross-sectional view of an electrical machine equipping a module according to the invention comprising a rotor having a static but balanced imbalance, along a plane perpendicular to the axis of rotation of the rotor; - [Fig.3] represents a schematic cross-sectional view of an electrical machine of a turbomachine module according to a first embodiment of the invention; - [Fig.4] is a partial schematic view of [Fig.3] before balancing the rotor of the electric machine; - [Fig.5] is a partial schematic view of [Fig.3] after balancing the rotor of the electric machine; - [Fig.6] represents a partial schematic cross-sectional view of an electrical machine of a turbomachine module according to a second embodiment of the invention before displacement of a magnet participating in the balancing of the rotor; - [Fig.7] is a schematic view of [Fig.6] after displacement of a magnet involved in balancing the rotor; - [Fig.8] is a schematic cross-sectional view along a plane perpendicular to the axis of rotation of the rotor of an electrical machine comprising a balanced rotor; - [Fig.9] is a schematic cross-sectional view along a plane perpendicular to the axis of rotation of the rotor of an electrical machine comprising an unbalanced rotor; - [Fig. 10] is a schematic cross-sectional view along a plane perpendicular to the axis of rotation of the rotor of an electrical machine comprising a rotor exhibiting static imbalance but rebalanced according to a third embodiment of the invention; and - [Fig.11] is an enlarged view of a framed area of ​​[Fig.10].

[0030] Elements having the same functions in the different implementations have the same references in the figures.

[0031] In the figures, the scales and proportions are not strictly respected for the purposes of illustration and clarity. Description of the implementation methods

[0032] Reference is first made to [Fig. 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 turbomachines equipped with an electric motor, for example a turboprop, without departing from the scope of the invention.

[0033] The turbomachine 10 has a longitudinal axis denoted C around which its various components extend.

[0034] The turbomachine 10 conventionally comprises a gas generator 12 upstream of which is arranged a blower 14. The blower 14 is surrounded by a blower housing 16 which is surrounded by a nacelle 18 which extends around and along a major part of the gas generator 12.

[0035] The gas generator 12 here comprises two bodies, namely a low-pressure body 12a or BP and a high-pressure body 12b or HP. Each body comprises a compressor and a turbine.

[0036] In the present invention, and generally, the terms "upstream" and "downstream" are defined with respect to a main direction F of fluid flow inside the turbomachine, and here along the longitudinal axis C, i.e. from left to right with reference to [Fig.1].

[0037] 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.

[0038] 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.

[0039] 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 reduction gear 33. The gas flow through the fan (arrow F) is separated upstream of the gas generator 12 by an annular nozzle 34 into an internal radially annular flow, called the primary flow 36 which supplies the gas generator 12, and into an external radially annular flow, called the secondary flow 38 which flows between the gas generator 12 and the nacelle 18 and provides most of the thrust of the turbomachine.

[0040] An inlet casing 40 structurally connects the gas generator 12 to the fan casing 16 and the nacelle 18. The inlet casing 40 comprises an annular row of radially internal arms 42 extending into the primary flow 36, and an annular row of radially external stator blades 44 (of the OGV type) extending into the secondary flow 38. The arms 42 are generally limited in number (fewer than ten) and are tubular and traversed by auxiliary passages. The number of blades 44 (OGV) is generally greater than ten.

[0041] The turbomachine comprises a module according to the invention including a shaft extending along an axial direction A, parallel to the longitudinal axis of the turbomachine and an electric machine 110. The ZI zone represents an area located between the blower disc 32 and the reducer 33, in which the electric machine can be installed. Zone Z2 represents another zone located downstream of the low pressure turbine 28 in which the electric machine can also be installed.

[0042] Alternatively, the electric machine can be integrated into the core of the turbomachine, for example mounted on the high-pressure body of the turbomachine.

[0043] In the description, the terms "internal" or "inside" and "external" or "outside" are used by way of non-limiting agreement with reference to the radial distance from the longitudinal axis C around which the turbomachine extends, the term "internal" defining an area radially closer to the longitudinal axis of the nacelle, as opposed to the term "external". Furthermore, in the description and the claims, the terminology axial, radial, and transverse shall be adopted by way of non-limiting agreement with reference to the trihedral axis A, R, T shown in the figures, the axial axis A being parallel to the longitudinal axis C of the turbomachine.

[0044] Figure 2 schematically represents a cross-sectional view of an electrical machine 110 equipping a module according to the invention. The electrical machine 110 has a generally annular shape and comprises a rotor 120 and a stator 130.

[0045] The rotor 120 has a general cylindrical shape extending circumferentially around an axis of rotation coinciding with the axis C of the turbomachine. The rotor is coupled with the module shaft, i.e. the blower shaft if the electric machine is installed downstream of the blower (Zone Z1) or the low-pressure turbine shaft if the electric machine is installed downstream of it (Zone Z2).

[0046] The rotor 120 exhibits static imbalance, along a cutting plane perpendicular to the axis of rotation of the rotor 120 which coincides with the longitudinal axis C of the turbomachine. In an orthogonal OXYZ coordinate system where the line OZ is the axis of rotation of the rotor 120, the cut is made along the XOY plane. Static imbalance is a balancing defect corresponding to an axis of inertia of the rotor 120 that is parallel to, and not coincident with, the OZ axis of rotation of the rotor 120. The imbalance This is due to an imbalance in the weight distribution of the rotor 120 around its OZ axis of rotation. During the rotation of the rotor 120, this imbalance manifests as a force perpendicular to the OZ axis of rotation of the rotor 120. Furthermore, the static unbalance alters the size of the air gap and consequently the permeance of the magnetic circuit. The electromagnetic efficiency of the machine is therefore locally greater and creates a radial restoring force oriented along the azimuth of the air gap closure. This unbalance force is thus added to the existing mechanical unbalance, which is the origin of the initial eccentricity. These two forces are represented in [Fig. 2] by a mechanical force Fl originating at a point M (representing the position of the unbalance) and collinear with the OX axis (since point M is on the OX axis).

[0047] The rotor 120 is driven in rotation for example by an electric machine, the rotation (represented by the arrow W) being generated by a stator magnetic field Bs generated by the stator 130 of the electric machine and a rotor magnetic field Br generated by the rotor 120.

[0048] The rotor 120 comprises an annular disk 122 and magnetic elements 124 arranged regularly around the periphery of the disk 122. The magnetic elements 124 are, for example, permanent magnets. The annular disk 122 is delimited by an inner circumferential surface 122A and an outer circumferential surface 122B. The magnetic elements 124 are radially internal with respect to the outer circumferential surface 122B. In the example illustrated in [Fig. 2], only one of the magnetic elements 124 has been shown for illustrative and clarity purposes. By "arranged regularly around the periphery of the disk 122" we mean that the magnetic elements 124 are close to the outer circumferential surface 122B, that is to say, they are closer to the outer circumferential surface 122B than to the inner circumferential surface 122A in a radial direction.

[0049] Generally, the magnetic elements 124 are shrink-fitted onto the disc 122 of the rotor 120.

[0050] The stator 130 comprises a ring 132 also having a general cylindrical shape extending circumferentially around the axis C of the module and the turbine. The stator 130 is integral with a housing of the module, for example the blower housing 16 (zone Z1). The ring 132 of the stator 130 is delimited by an internal surface 132A, i.e. a radially internal surface and an external surface 132B, i.e. a radially external surface. The stator ring 132 supports a winding (not shown) consisting of several coils arranged in an annular pattern within the ring. More specifically, the stator ring 132 includes notches in which the coils. Each coil is formed of a conductive wire wound around a support, the support being fixed to the ring 132 of the stator.

[0051] The stator 130 surrounds the rotor 120. In other words, the ring 132 of the stator 130 and the disk 122 of the rotor 120 are concentric, and the ring 132 of the stator is radially external to the disk 122 of the rotor 120. The coils are arranged opposite 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 internal with respect to the coils of the stator 130.

[0052] The electric machine 110 further comprises an inverter-type power supply (not illustrated) supplying polyphase current to the winding.

[0053] Furthermore, the air gap of the electric machine defined by the distance along a radial direction between the magnetic elements and the coils is between 0.5 mm and 10.0 mm.

[0054] According to the invention, the rotor 120 has a balancing defect represented by the mechanical force Fl when the magnetic elements near the azimuth of the force Fl are in a first position in which the magnetic elements 124 are radially abutted against the disk 122 of the rotor 120 and more precisely abutted against the internal surface 122A of the disk 122 of the rotor 120. In this case, the magnetic elements near the opposite of the azimuth of the force Fl are in a position in which they are radially abutted against the external surface 122B of the disk 122 of the rotor 120.

[0055] Furthermore, according to the invention, to balance such a rotor, at least one magnetic element 124 is movable from the first position to a second position adapted to apply to the rotor 120 a so-called magnetic force F2 opposed to the mechanical force Fl when the electric machine 110 is in operation.

[0056] Indeed, the movement of one or more appropriate magnetic element(s) 124 generates the establishment of a magnetic imbalance which complements the mechanical imbalance due to the movement of the magnets. The mechanical imbalance due to the displacement of the magnets manifests as a force perpendicular to the OZ axis and is represented in [Fig. 2] by a force F21 originating at point N and collinear with the OX axis. Point N represents the position of the mechanical imbalance generated by the displacement of the appropriate magnetic element(s). By appropriate magnetic element(s), we mean a set of magnetic elements, from among all the magnetic elements of the rotor 120, whose center of gravity is arranged at an azimuth opposite to the identified imbalance defect. In other words, points M and N have opposite azimuths and are therefore substantially symmetrical with respect to the center of gravity of the rotor O.

[0057] Similarly, the magnetic imbalance due to the displacement of the magnets manifests itself by a force perpendicular to the OZ axis and is symbolized on [Fig.2] by a force F22 originating at point N and collinear with the OX axis. The sum of the forces F21 and F22 is equal to the magnetic force F2 opposite to the mechanical force Fl.

[0058] The displacement of one or more appropriate magnetic element(s) 124 therefore makes it possible to compensate for the identified imbalance defect in order to balance the rotor 120 during its rotation using only parts already available in the turbomachine and consequently without adding additional mass which could degrade the performance of the turbomachine.

[0059] Figures 3 to 5 refer to a first embodiment of a module according to the invention.

[0060] According to this first embodiment, the rotor 120 includes several radial adjustment devices 140. Each radial adjustment device 140 is associated with a magnetic element 124 and configured to radially move the magnetic element 124 between the first position and the second position.

[0061] In the example illustrated in [Fig.3], the rotor 120 here comprises six magnetic elements 124 and therefore six radial adjustment devices 140 for the purposes of illustration and clarity, but may comprise a higher or lower number of magnetic elements 124 (and consequently of radial adjustment devices 140), depending on the desired characteristics of the electric machine (in particular rotational speed).

[0062] Fig. 4 illustrates a magnetic element 124 in the first position, i.e. radially against the disk 142 of the rotor 120 and more precisely against the internal surface 122A of the disk of the rotor 120.

[0063] Figure 5 illustrates the same magnetic element 124 in the second position, i.e., displaced radially outwards towards the stator 130, i.e., radially outwards relative to the first position. Such a magnetic element 124 is displaced to compensate for the initial unbalance fault of the rotor; it is therefore in a region located at the azimuth opposite to the initial unbalance fault.

[0064] More specifically, each radial adjustment device 140 is configured to adjust the distance between one of the internal 122A and external 122B surfaces of the disk 122 of the rotor 120 and the magnetic element 124 in the radial direction R outwards as a function of the magnetic force F2 to be applied to the rotor 120. In the example illustrated in Figures 3 to 5, each radial adjustment device 140 is configured to adjust the distance between the internal surface 122A of the disk 122 of the rotor 120 and the magnetic element 124 in the radial direction R outwards.

[0065] Thus, figures 4 and 5 illustrate respectively the initial state and the final state of a magnetic element 124 actuated by the radial adjustment device 140.

[0066] According to this first embodiment, each radial adjustment device 140 comprises a screw 142 having a first end 142A fixed to the associated magnetic element 124 and a second end 142B connected to the rotor disc 124. For example, the screw 142 generally has a head and a body. The head of the screw 142 is integral with the magnetic element 124, while the body of the screw 142 extends radially inward from the head of the screw and passes through an opening in the disk 122 (more precisely through the inner surface 122A) of the rotor, and the second end 142B of the screw is held against the inner surface 122A of the disk 124 of the rotor by a nut 144. The head of the screw 142 is integral with the magnetic element 124 preferably by welding or by additive manufacturing. Thus, the screw 142 is configured so that a rotation of the screw 142 in one direction causes a radial displacement of the associated magnetic element 124 towards the second position ([Fig.5]), and conversely a rotation of the screw 142 in the opposite direction causes a radial displacement of the associated magnetic element 124 towards the first position ([Fig.4]).

[0067] Thus, initially all the magnetic elements 124 of the rotor are in contact with the outer surface of the disk 122 of the electric machine rotor. When balancing is required, one or more magnetic elements 124 arranged at an identified azimuth are moved radially via the screws 142 by a value calculated by an operator responsible for balancing, the unbalance transfer function per number of screw turns having been previously defined.

[0068] Thanks to this first embodiment, the radial position of the magnetic elements can be adjusted from inside the rotor by the screw system of the adjustment device.

[0069] For an electric machine installed on a blower rotor of a geared motor having a low speed between 500 and 3000 rpm, the magnetic imbalance generated by an eccentricity of the rotor's axis of rotation of 0.2 to 0.5 mm is on the order of 500 to 7000 cm.g. The inventors have estimated that the invention makes it possible to correct this magnetic imbalance, in particular by a displacement of a magnetic element of 2 to 3 mm or alternatively by a displacement of two magnets of 0.5 to 1.0 mm, depending on the value of the air gap.

[0070] According to another application, in the case of an electric machine installed on a low-pressure rotor of a geared motor (having an average speed between 6000 and 10000 rpm), the magnetic imbalance generated by an eccentricity of the rotor's axis of rotation of 0.1 to 0.3 mm is on the order of 500 cm.g. In this case, thanks to the invention, a displacement of a magnet of less than 1 mm is necessary to correct this magnetic imbalance according to the invention.

[0071] Figures 6 to 7 refer to a second embodiment of a module according to the invention which differs from the first by the radial adjustment device 240 of the 124 magnetic elements.

[0072] According to this second embodiment, the rotor 120 also includes several radial adjustment devices 240. Each radial adjustment device 240 is associated with a magnetic element 124 and configured to radially move the magnetic element 124 between the first position and the second position.

[0073] Fig. 6 illustrates a magnetic element 124 in the first position, i.e. radially against the disk 122 of the rotor 120 and more precisely against the internal surface 122A of the disk 122 of the rotor 120.

[0074] Figure 7 illustrates the same magnetic element 124 in the second position, i.e., displaced radially outwards towards the stator 130, i.e., radially outwards relative to the first position. Such a magnetic element 124 is displaced to compensate for the initial unbalance fault of the rotor; it is therefore in a region located at the azimuth opposite to the initial unbalance fault.

[0075] More specifically, each radial adjustment device 240 is configured to adjust the distance between one of the internal 122A and external 122B surfaces of the disk 122 of the rotor 120 and the magnetic element 124 in the radial direction R outwards as a function of the magnetic force F2 to be applied to the rotor 120. In the example illustrated in Figures 6 and 7, each radial adjustment device 140 is configured to adjust the distance between the internal surface 122A of the disk 122 of the rotor 120 and the magnetic element 124 in the radial direction R outwards.

[0076] Thus, figures 6 and 7 respectively illustrate the initial state and the final state of a magnetic element 124 actuated by the radial adjustment device 240.

[0077] According to this second embodiment, each radial adjustment device 240 comprises an elastic element formed of one or more elastic slat(s) and two inclined planes 244. Each elastic strip 242 is arranged between the associated magnetic element 124 and the inner surface 122A of the rotor disk 122. These are configured to move the magnetic element 124 radially outward along arrow F3 in the illustrated example. In other words, the elastic strip assembly is configured to move the magnetic element 124 radially toward the stator 130. In the illustrated example, the elastic element, consisting of one or more elastic strips, is arranged to return the magnetic element 124 to the stator 130. More precisely, the elastic strip assembly is configured to maintain contact between the magnetic element 124 and the inclined planes 244. Alternatively, any other return element configured to return the magnetic element 124 to the stator 130 can be used, for example, one or more springs.

[0078] Each inclined plane 244 is arranged between the stator 130 and the disc 122 of the rotor 120 and in contact with the magnetic element 124. More precisely, a first inclined plane 244A is in contact with a first tangential end 124A of the magnetic element, while a second inclined plane 244B is in contact with a second tangential end 124B of the magnetic element. The respective surface areas of the inclined planes 244A and 244B are complementary to the respective surface areas of the tangential ends 124A and 124B with which they are in contact. Preferably, the inclined planes 244A and 244B and the surfaces of the tangential ends 124A and 124B form an angle between 40° and 50° with the radial direction R, and preferably an angle of approximately 45°.

[0079] The first inclined plane 244A is movable relative to the disk 122 of the rotor 120 while the second inclined plane 244B is fixed to the disk 122 of the rotor 120. More precisely, the first inclined plane 244A is movable in translation along a tangential direction T, that is to say perpendicular to the radial direction R relative to the disk 122 of the rotor 120. The inclined planes 244A, 244B and the magnetic element 124 are configured to cooperate such that a translation of the first inclined plane 244A results in a radial displacement of the associated magnetic element 124. Thus, as illustrated in [Fig. 7], a translation of the first inclined plane 244A along arrow F4 results in a radial displacement of the associated magnetic element 124 along arrow F3.

[0080] The radial adjustment device 240 further includes an adjustment screw 246 for adjusting the tangential position of the first inclined plane 244A, which in turn adjusts the radial position of the magnetic element 124. Thus, the screw 246 is configured so that a rotation of the screw 246 in one direction causes a radial displacement of the associated magnetic element 124 towards the second position ([Fig.7]), and conversely, a rotation of the screw 246 in the opposite direction causes a radial displacement of the associated magnetic element 124 towards the first position ([Fig.6]).

[0081] Thus, initially all the magnetic elements 124 of the rotor are in contact with the internal surface 122A of the disk 122 of the rotor 120 of the electric machine. When balancing is required, one or more magnetic elements 124 arranged at an identified azimuth are moved radially by their associated adjusting device 240 by a value calculated by an operator responsible for balancing, the unbalance transfer function per number of screw turns having been previously defined.

[0082] This second embodiment is particularly suitable when the electrical machine has a limited diameter that does not allow for the integration of a magnet adjustment device from inside the rotor according to the first embodiment, especially when the diameter is less than 200 mm. Indeed, this adjustment device 240 according to the second embodiment allows for the adjustment of the radial position of the magnetic element by a so-called lateral adjustment of the inclined plane since the screw of The adjustment is easily accessible on the side of the electric machine.

[0083] Figures 8, 9, 10 and 11 refer to a third embodiment of a module according to the invention.

[0084] According to this third embodiment, the rotor 220 is mobile in translation so as to collectively move all the magnetic elements 124 towards a second position adapted to apply to the rotor a magnetic force F2 opposite to the mechanical force when the electric machine is in operation.

[0085] Advantageously, the balancing effect will be all the more important.

[0086] According to this third embodiment, the rotor 320 comprises a ring 322 of magnetic elements (not visible) arranged between an internal surface 320A and an external surface 320B of the rotor 320, each of which can be formed by a ring of the fret.

[0087] Fig. 8 illustrates the case of a balanced rotor, i.e. that the center and axis of rotation denoted O of the rotor 320 coincide respectively with the center and axis of rotation of the stator 130 which coincides with the axis C of the turbomachine module.

[0088] Fig. 9 schematically represents the case of an unbalanced rotor, i.e. that the center and axis of rotation O of the rotor 320 no longer coincide respectively with the center and axis of rotation C of the stator 130.

[0089] According to this third embodiment, the rotor 320 comprises several radial adjustment devices 340 similar to those of the first embodiment. The radial adjustment devices 340 are regularly distributed in an annular manner within the ring 322 of magnetic elements.

[0090] Each radial adjustment device 340 comprises a screw or threaded rod 342 having a first end 342A fixed to the ring 322 of magnetic elements by a ball joint. The screw or threaded rod 342 has a second end 342B connected to the inner surface 320A of the rotor in the illustrated example. The screw or threaded rod 342 extends radially inward from the ring 322 of magnetic elements and passes through an opening in the inner surface 320A of the rotor. The second end 342B of the screw is held against the inner surface 320A of the rotor by a nut 344. Each radial adjustment device 340 is thus configured to adjust the distance between one of the internal 320A and external 320B surfaces of the rotor 320 and the ring 322 of magnetic elements in the radial direction R as a function of the magnetic force F2 to be applied to the rotor 120. In the example illustrated in figures 9 and 10, each radial adjustment device 140 is configured to adjust the distance between the internal 320A surface of the rotor 320 and the ring 322 of magnetic elements in the radial direction R.

[0091] Alternatively, each radial adjustment device 140 is configured to adjust the The distance between the outer surface 320B of the rotor 320 and the ring 322 of magnetic elements in the radial direction R. In this case, the screw or threaded rod 342 extends radially outward from the ring 322 of magnetic elements and passes through an opening in the outer surface 320B of the rotor. The other end 342B of the screw is held against the inner surface 320B of the rotor by a nut 344.

[0092] Each radial adjustment device 340 is thus configured to radially move the ring 322 of magnetic elements between the first position ([Fig.9]) and the second position ([Fig. 10]).

[0093] Fig. 10 illustrates the eccentricity of the ring 322 of magnetic elements such that the center of the ring 322 of magnetic elements, denoted P, coincides with the center C of the stator 130, while the center O of the rotor is distinct from the center C of the stator 130.

[0094] A method for balancing a rotor of a module according to the invention and as described above will now be detailed. This method comprises at least the following steps: - determine the characteristics of the mechanical force Fl representing the imbalance defect; - determine the displacement of at least one magnetic element 124 to be moved to balance the rotor as a function of the determined mechanical force; - move at least one magnetic element 124 to be moved by the determined displacement in order to balance the rotor.

[0095] In particular, for modules according to the first and second embodiments, the step of determining the displacement of at least one magnetic element to be moved comprises at least the following steps: - determine at least one magnetic element to be moved to balance the rotor according to the determined mechanical force; and - for each magnetic element to be moved determined, determine the distance of displacement of the magnetic element as a function of the determined mechanical force.

Claims

Demands

1. Module 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;320) coupled in rotation with the module shaft, the rotor comprising a disk (122) and magnetic elements (124) arranged regularly around the periphery of the disk, and - a stator (130) integral with a module housing comprising a ring (132) and coils distributed annularly inside the stator ring, the coils are arranged outside the magnetic elements of the rotor in a radial direction, characterized in that: - the rotor has an imbalance defect represented by a mechanical force (F1) when the magnetic elements are in a first position, and - at least one magnetic element (124) is movable from the first position to a second position adapted to apply to the rotor a magnetic force (F2) opposite to the mechanical force when the electric machine is in operation.;

2. Module according to claim 1, wherein each magnetic element is radially movable between the first position and the second position and the magnetic elements are radially abutted against the rotor disk in the first position.

3. Module according to claim 2, wherein the rotor (120) has radial adjustment devices (140; 240), each associated with a magnetic element (124) and adapted to adjust the distance between the rotor disk (122) and the magnetic element (124) in an outward radial direction as a function of the magnetic force (F2) to be applied to the rotor (120).

4. Module according to claim 3, wherein each radial adjustment device (140) comprises a screw (142) having a first end (142A) fixed to the associated magnetic element (124) and a second end (142B) connected to the rotor disk and adapted so that a rotation of the screw causes a radial displacement of the associated magnetic element.

5. Module according to claim 3, wherein each radial adjustment device (240) comprises: - at least one elastic strip (242) arranged between the associated magnetic element and the rotor disk, - a first fixed inclined plane (244B) arranged between the stator (130) and the rotor disk (120) and in contact with a first tangential end (124B) of the magnetic element, - a second movable inclined plane (244A) arranged between the stator and the rotor disk and in contact with a second tangential end of the magnetic element opposite to the first tangential end, the second inclined plane being movable in translation along a tangential direction perpendicular to the radial direction and the inclined planes and the magnetic element are configured to cooperate so that a translation of the second inclined plane causes a radial displacement of the associated magnetic element.

6. Module according to claim 1, wherein the rotor (320) is translationally movable so as to collectively move the magnetic elements to a second position adapted to apply to the rotor a magnetic force (F2) opposite to the mechanical force (Fl) when the electric machine is in operation.

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

8. A method for balancing a rotor of a module according to any one of the preceding claims 1 to 6, comprising at least the following steps: - determining the mechanical force representative of the imbalance defect; - determining the displacement of at least one magnetic element to be moved to balance the rotor as a function of the determined mechanical force; - moving the at least one magnetic element to be moved by the determined displacement so as to balance the rotor.

9. Balancing method according to claim 8 when it depends on any one of claims 1 to 5, wherein the step of determining the displacement of at least one magnetic element to be moved comprises at least the following steps: - determining at least one magnetic element to be moved to balance the rotor as a function of the determined mechanical force; and - for each determined magnetic element to be moved, determining the distance of displacement of the magnetic element as a function of the determined mechanical force.

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