TURBOMACHINE MODULE EQUIPPED WITH AN ELECTRIC MACHINE

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 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 (132) 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, in which the rotor has a balance 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 abstract: 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. Prior art

[0003] The aeronautical world is currently asking itself 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.

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

[0005] These architectures can in particular be based on a high dilution 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 rotor of a compressor to a rotor of a turbine.

[0006] 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.

[0007] Thus, depending on the final use of an electric machine, the terms: - generator to designate an electrical machine producing electrical energy from mechanical energy, - motor for an electric machine producing mechanical energy from electrical energy.

[0008] An electrical 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.

[0009] 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 that is usually found on the accessory box (AGB) and which draws power from the high-pressure body if the electrical machine is integrated on the low-pressure body of a turbomachine.

[0010] Several installation zones are possible but the advantages and disadvantages of each are numerous and diverse (problem of mechanical integration 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 electrical machine downstream of a blower. In addition, the electrical machine can also be installed downstream of a turbine shaft and driven by this shaft.

[0011] The electrical machine has a generally annular shape and comprises a rotor and a stator. The rotor and the 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 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 relative to the magnetic elements.

[0012] Parts rotating around an axis of rotation, such as the rotors of a compressor, a turbine or an electrical machine, generally have, following their manufacture, a balancing defect called unbalance, which is due to a non-coincidence of the axis of rotation of a part with its axis of inertia. This non-coincidence leads to the appearance of mechanical forces which can damage the equipment in which the rotating parts are present, 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) whereas dynamic eccentricity is a defect that commonly appears in overall dynamics. It is linked to the presence of a mechanical imbalance. More specifically, a commonly encountered static unbalance is one in which the part's axis of inertia is parallel to, but distinct from, the part's axis of rotation. Another known balance defect is torque unbalance (otherwise known as torque unbalance), in which the center of gravity is located on the axis of rotation but the axis of inertia forms a non-zero angle with the axis of rotation. The combination of a static unbalance and an unbalance torque is called dynamic unbalance. The unbalance torque is, however, negligible when the diameter of the part is large compared to the length of the part, and the dynamic unbalance is equivalent to the static unbalance.

[0014] In the particular case of an electrical machine rotor, these defects modify the width 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 return force oriented according to the azimuth of the closing of the air gap clearance. It is therefore a so-called magnetic unbalance force which is added to the already existing mechanical unbalance and at the origin of the initial eccentricity.

[0015] To correct mechanical unbalance, current manufacturing processes include a balancing step, in which mass is added to or removed from the part, in particular 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 station closest to the unbalance defect to be corrected and at the azimuth opposite the identified defect. This traditional balancing requires providing a position for adding the mass with a flange with a fairly fine angular discretization. In addition, it is also necessary to provide the definition of the parts allowing the addition of the mass: screw, nut, weight, clips, etc. which are parts dedicated to balancing the rotating part but greatly increase the mass of the turbomachine concerned.

[0016] The objective of the present invention is to overcome at least some of the problems mentioned in the above. In particular, the present invention proposes a solution making it possible to balance a turbomachine rotor comprising an electric machine without adding additional mass which could degrade the performance of the turbomachine. Summary of the invention

[0017] For this purpose, 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: - a rotor coupled in rotation with the shaft of the module, the rotor comprising a disk and magnetic elements arranged regularly around the periphery of the disk, and - a stator secured to a module casing 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 has a balance defect represented by a mechanical force when the magnetic elements are in a first position, and at at least one magnetic element is movable from the first position to a second position adapted to apply to the rotor a magnetic force opposite the mechanical force when the electrical machine is in operation.

[0018] A rotor is understood to mean a part that can be rotated, via a magnetic field, by an electric rotating machine comprising a stator. The rotor is held and guided in rotation by bearings, for example of the rolling bearing type.

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

[0020] More specifically, the invention proposes to move mainly radially magnets of the rotor of the electric machine in order to balance the rotor thanks to the mechanical effect but also by exploiting the magnetic unbalance effect. The radial displacement of the magnets being limited by the air gap available between the rotor and the stator of the electric machine, the invention takes advantage of the magnetic unbalance created in order to achieve the required balancing force. Indeed, the radial displacement of the magnets already present to balance the rotor causes the establishment of a magnetic unbalance which complements the mechanical unbalance due to the displacement of the magnets. Thus, the mechanical effect usually used to balance the rotor is supplemented or even replaced by the magnetic effect.This makes it possible to pool the functions of the different equipment of the turbomachine and to increase the balancing capacity or even in certain cases to make possible so-called balancing in an inaccessible zone for the addition of additional mass according to the prior art.

[0021] The invention thus makes it possible to balance a turbomachine rotor comprising an electric machine by making use 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 characteristics, taken in isolation from one another or in combination with one another according to all technically possible combinations: - each magnetic element is radially movable between the first position and the second position and the magnetic elements are radially in abutment on the rotor disc in the first position; - the rotor comprises radial adjustment devices, each associated with a magnetic element and adapted to adjust the distance between the rotor disc and the magnetic element in a radial outward direction depending on the magnetic force to be applied to the rotor; - each radial adjustment device comprises 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 disc and in contact with a second tangential end of the magnetic element opposite the first tangential end, the second inclined plane being movable in translation in a tangential direction perpendicular to the radial direction and the inclined planes and the magnetic element are shaped to cooperate so that a translation of the second inclined plane causes a radial displacement of the associated magnetic element; - the rotor is movable in translation so as to collectively move the magnetic elements to a second position adapted to apply to the rotor a magnetic force opposed to the mechanical force when the electrical 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 previously.

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

[0025] Alternatively, the module is a turbine module and the electrical 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 heart of the turbomachine. It is for example 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 balance defect; - determine the displacement of at least one magnetic element to be moved to balance the rotor according to the determined mechanical force; - move the at least one magnetic element to be moved by the determined displacement so as to balance the rotor.

[0028] According to one embodiment, 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, determine the distance of movement 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, 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: - [Fig.l] 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; - [Fig.2] is a schematic sectional view of an electrical machine equipping a module according to the invention comprising a rotor having a static but balanced unbalance, along a plane perpendicular to the axis of rotation of the rotor; - [Fig.3] represents a schematic cross-sectional view of an electric 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 electric machine of a turbomachine module according to a second embodiment of the invention before movement of a magnet participating in the balancing of the rotor; - [Fig.7] is a schematic view of [Fig.6] after displacement of a magnet participating in the balancing of the rotor; - [Fig.8] is a schematic 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 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 sectional view along a plane perpendicular to the axis of rotation of the rotor of an electrical machine comprising a rotor having a static unbalance but rebalanced according to a third embodiment of the invention; and - [Fig.11] is an enlarged view of a boxed area of ​​[Fig.10].

[0030] Elements having the same functions in 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 embodiments

[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 turbomachine equipped with an electric machine, 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 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.

[0035] 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.

[0036] In the present invention, and generally, 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 [Fig.l].

[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 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.

[0040] 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 internal arms 42 extending into the primary flow 36, and an annular row of radially external 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 services. The number of vanes 44 (OGV) is generally greater than ten.

[0041] The turbomachine comprises a module 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. Zone ZI represents an area located between the fan 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 heart of the turbomachine, for example mounted on the high pressure body of the turbomachine.

[0043] 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 C of the turbomachine.

[0044] [Fig. 2] schematically represents a 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 generally cylindrical shape extending circumferentially around an axis of rotation coinciding with the axis C of the turbomachine. The rotor is coupled with the shaft of the module, 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).

[0046] The rotor 120 has a static unbalance, according to a section 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 reference frame where the line OZ is the axis of rotation of the rotor 120, the section is carried out according to the plane XOY. Static unbalance is a balancing defect corresponding to an axis of inertia of the rotor 120 parallel and not confused with the OZ axis of rotation of the rotor 120. The unbalance is due to an imbalance in the weight distribution of the rotor 120 around the OZ axis of rotation. When the rotor 120 rotates, this imbalance manifests itself as a force perpendicular to the OZ axis of rotation of the rotor 120. In addition, the static unbalance modifies the dimension 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 according to the azimuth of the closing of the air gap clearance. It is therefore an unbalance force which is added to the already existing mechanical unbalance and at the origin of the initial eccentricity. These two forces are symbolized in [Fig.2] by a mechanical force Fl originating from a point M (representative of the position of the unbalance) and collinear with the OX axis (because the 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 disc 122 and magnetic elements 124 arranged regularly on the periphery of the disc 122. The magnetic elements 124 are, for example, permanent magnets. The annular disc 122 is delimited by an inner circumferential surface 122A and an outer circumferential surface 122B. The magnetic elements 124 are radially inward relative to the outer circumferential surface 122B. In the example illustrated in [Fig.2], only one of the magnetic elements 124 has been shown for the purposes of illustration and clarity. By "arranged regularly around the periphery of the disk 122" is meant that the magnetic elements 124 are close to the outer circumferential surface 122B, i.e. 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 shrunk onto the disc 122 of the rotor 120.

[0050] The stator 130 comprises a ring 132 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). The ring 132 of the stator 130 is delimited by an internal surface 132A, that is to say a radially inner surface and an external surface 132B, that is to say a radially outer surface. The stator ring 132 supports a winding (not shown) formed of several coils distributed in an annular manner inside the ring. More specifically, the stator ring 132 comprises 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 disc 122 of the rotor 120 are concentric and the ring 132 of the stator is radially outside the disc 122 of the rotor 120. The coils 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 of the stator 130.

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

[0053] Furthermore, the air gap of the electrical machine defined by the distance in 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 balance defect represented by the mechanical force F1 when the magnetic elements near the azimuth of the force F1 are in a first position in which the magnetic elements 124 are radially in abutment on the disc 122 of the rotor 120 and more precisely in abutment against the internal surface 122A of the disc 122 of the rotor 120. In this case, the magnetic elements near the opposite of the azimuth of the force F1 are in a position in which they are radially in abutment against the external surface 122B of the disc 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 opposite to the mechanical force F1 when the electrical machine 110 is in operation.

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

[0057] Similarly, the magnetic unbalance due to the movement of the magnets is manifested by a force perpendicular to the OZ axis and is symbolized in [Fig.2] by a force F22 originating at point N and colinear with the OX axis. The sum of the forces F21 and F22 is equal to the magnetic force F2 opposed 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 comprises 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 electrical machine (rotation speed in particular).

[0062] [Fig.4] illustrates a magnetic element 124 in the first position, that is to say radially in abutment on the disc 142 of the rotor 120 and more precisely in abutment against the internal surface 122A of the disc of the rotor 120.

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

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

[0065] Thus, Figures 4 and 5 respectively illustrate 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 disc 124 of the rotor. For example, the screw 142 generally has a head and a body. The head of the screw 142 is secured to the magnetic element 124 while the body of the screw 142 extends from the head of the screw radially inward and passes through an orifice provided in the disc 122 (more precisely through the internal surface 122A) of the rotor and the second end 142B of the screw is held against the internal surface 122A of the disc 124 of the rotor by a nut 144. The head of the screw 142 is secured to 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 an 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 abutment on the external surface of the disc 122 of the rotor of the electric machine. When balancing is required, one or more magnetic elements 124 arranged at an identified azimuth are displaced 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 the inside of the rotor by the screw system of the adjustment device.

[0069] For an electrical machine installed on a fan rotor of a geared motor having a low speed of between 500 and 3000 rpm, the magnetic unbalance generated by an eccentricity of the axis of rotation of the rotor of 0.2 to 0.5 mm is of the order of 500 to 7000 cm.g. The inventors have estimated that the invention makes it possible to correct this magnetic unbalance, 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 electrical machine installed on a low pressure rotor of a geared motor (having an average speed of between 6000 and 10000 rpm), the magnetic unbalance generated by an eccentricity of the axis of rotation of the rotor of 0.1 to 0.3 mm is of 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 unbalance 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 magnetic elements 124.

[0072] According to this second embodiment, the rotor 120 also comprises 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, that is to say radially in abutment against the disc 122 of the rotor 120 and more precisely in abutment against the internal surface 122A of the disc 122 of the rotor 120.

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

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

[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 from one or more elastic strip(s) and two inclined planes 244. The or each elastic strip 242 is arranged between the associated magnetic element 124 and the inner surface 122A of the rotor disc 122. These are configured to move the magnetic element 124 radially outwards according to the arrow F3 in the illustrated example. In other words, the set of elastic lamellae is configured to move the magnetic element 124 radially towards the stator 130. In the illustrated example, the elastic element formed of one or more elastic lamellae is arranged to bring back / return the magnetic element 124 towards the stator 130. More precisely, the set of elastic lamellae is configured to maintain the contacts between the magnetic element 124 and the inclined planes 244. Alternatively, any other return element configured to bring back / return the magnetic element 124 towards 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 specifically, 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 of the inclined planes 244A, 244B is complementary to the respective surface of the tangential end 124A, 124B with which it is in contact. Preferably, the inclined planes 244A, 244B and the surfaces of the tangential ends 124A, 124B make an angle of 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 in 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 shaped to cooperate so that a translation of the first inclined plane 244A causes a radial displacement of the associated magnetic element 124. Thus, as illustrated in [Fig.7], a translation of the first inclined plane 244A along the arrow F4 causes a radial displacement of the associated magnetic element 124 along the arrow F3.

[0080] The radial adjustment device 240 further comprises an adjustment screw 246 making it possible to adjust the tangential position of the first inclined plane 244A making it possible to adjust 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 an 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 abutment on the internal surface 122A of the disc 122 of the rotor 120 of the electrical machine. When balancing is required, one or more magnetic elements 124 arranged at an identified azimuth are displaced radially by their associated adjustment 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 which does not allow the integration of a device for adjusting the magnets from the inside of the rotor according to the first embodiment, in particular when the diameter is less than 200 mm. Indeed, this adjustment device 240 according to the second embodiment makes it possible to adjust the radial position of the magnetic element by a so-called lateral adjustment of the inclined plane since the screw 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 movable 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 electrical machine is in operation.

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

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

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

[0088] [Fig.9] schematically represents the case of an unbalanced rotor, that is to say that the center and the axis of rotation O of the rotor 320 no longer coincide respectively with the center and the 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 inside the crown 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 from the ring 322 of magnetic elements radially inward and passes through an orifice formed 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 inner 320A and outer 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 FIGS. 9 and 10, each radial adjustment device 140 is configured to adjust the distance between the inner surface 320A 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 distance between the external 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 from the ring 322 of magnetic elements radially outwards and passes through an orifice provided in the external surface 320B of the rotor. The second end 342B of the screw is held against the internal 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 crown 322 of magnetic elements so that the center of the crown 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 previously will now be detailed. This method comprises at least the following steps: - determine the characteristics of the mechanical force Fl representative of the balance defect; - determining the displacement of at least one magnetic element 124 to be moved to balance the rotor as a function of the determined mechanical force; - moving the at least one magnetic element 124 to be moved by the determined displacement so as to balance the rotor.

[0095] In particular, for the modules according to the first and second embodiments, the step of determining the displacement of at least one magnetic element to be displaced 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, determine the distance of movement of the magnetic element as a function of the determined mechanical force.

Claims

Claims

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 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 (132) 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: - the rotor has a balance 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 electrical machine is in operation.;

2. A 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 in abutment on the rotor disc in the first position.

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

4. Module according to claim 3, in which 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 and adapted so that a rotation of the screw causes a radial displacement of the associated magnetic element.

5. Module according to claim 3, in which each radial adjustment device (240) comprises: - at least one elastic strip (242) arranged between the associated magnetic element and the rotor disc, - a first fixed inclined plane (244B) arranged between the stator (130) and the rotor disc (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 disc and in contact with a second tangential end of the magnetic element opposite the first tangential end, the second inclined plane being movable in translation in a tangential direction perpendicular to the radial direction and the inclined planes and the magnetic element are shaped 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, in which the rotor (320) is movable in translation so as to collectively move the magnetic elements towards a second position adapted to apply to the rotor a magnetic force (F2) opposite to the mechanical force (F1) when the electrical machine is in operation.

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

8. Method for balancing a rotor of a module according to one of the preceding claims 1 to 6, comprising at least the following steps: - determining the mechanical force representative of the balancing 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 one of claims 1 to 5, in which 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 displacement distance of the magnetic element as a function of the determined mechanical force.

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