Compressor with rotating electric machine for axial turbo engine

Description

technical field

[0001] The invention relates to the field of electrical power generation and the rotational drive of a turbomachine, particularly its compressor. The invention also relates to an axial turbomachine, such as an aircraft turbojet or turboprop engine. The invention further provides a method for compressing a fluid within a turbomachine. Previous technique

[0002] The use of electrical power is increasing in aircraft operation. Electricity is being used to power various electrical actuators, replacing hydraulic actuators.

[0003] US patent 2010 / 0326050 A1 discloses a turbojet engine comprising a fan coupled to a turbine via an epicyclic gearbox. The turbine also drives a compressor and an electric generator. However, the electrical power produced remains limited. Furthermore, the heat generated can damage the permanent magnets, thus significantly impacting the generator's lifespan.

[0004] The published patent document EP 2 280 150 A1 discloses a turbomachine compressor comprising an integrated electric machine which is configured to generate an electric current for the operation of accessory components and to ensure a start-up of said turbomachine.

[0005] However, the solution proposed by the document has room for improvement, particularly to increase electricity production as well as the longevity and reliability of the electric machine. Summary of the invention Technical problem

[0006] The invention aims to solve at least one of the problems posed by the prior art. More specifically, the invention aims to increase electrical output in a turbomachine. The invention also aims to improve the lifespan and reliability of a turbomachine's power generator. The invention further aims to provide a simple, robust, lightweight, economical, reliable, and easily inspectable solution. Technical solution

[0007] In general, the invention relates to an axial turbomachine with a compressor equipped with an axial magnetic flux electric machine, the definition of the magnets and / or coils remaining optional.

[0008] The invention relates to an axial turbomachine, in particular an aircraft turbojet, the turbomachine comprising a compressor with a rotor and a stator, a turbine, a combustion chamber axially between the compressor and the turbine, and a rotating electrical machine coupled in rotation to the compressor, the compressor comprising an inner shell (50) supporting a row of stator blades (26) extending radially outward from the inner shell (50), notable in that the inner shell (50) comprises a wall (52) radially outward with respect to the rotating electrical machine (30) and delimiting a primary flow of the compressor (4;6), the rotating electrical machine being axially magnetic flux, and comprising an annular row of axially magnetic flux coils, a first annular row of axially magnetic flux permanent magnets (40), a second annular row of axially flux permanent magnets (40), and an axial gap (E) between the first row of magnets (40) and the second row of magnets (40), said axial gap (E) being axially shorter than the outer wall (52) of the shell (50) and / or than the stator blades (26), the annular row of coils occupies the axial gap, the coils are fixed to the stator, and the permanent magnets are fixed to the rotor.;

[0009] According to advantageous embodiments of the invention, the turbomachine may comprise one or more of the following features, taken individually or in all possible technical combinations: The compressor includes an external stator supporting the annular row of coils. The external stator includes the annular row of stator blades, at least one of said blades having electrical connections radially passing through said blade and electrically connected to the annular row of coils, or to at least one of the coils. The inner shell has a radial thickness in which the annular row of coils is radially arranged. The inner shell includes the outer wall delimiting a primary runner of the compressor and an internal support in which the annular row of coils, or at least one coil, is arranged, the internal support being, in particular, axially shorter than the outer wall. At least one or each coil of the annular row of coils includes a magnetic core axially passing through the corresponding coil.The compressor includes a sealing device within the radial thickness of the rotating electrical machine to ensure a seal between the rotor and the stator. The compressor includes an upstream inlet, with the annular row of magnets and / or the annular row of coils arranged axially at the upstream inlet. The rotor comprises a main body made of a first material, in particular a non-magnetic material, and a ferromagnetic part in magnetic contact with the annular row of permanent magnets. The ferromagnetic part is capable of forming a magnetic circuit in combination with one of the coils, said magnetic circuit passing axially through said coil, the ferromagnetic part including, in particular, an axial portion between two radial portions.The rotor comprises a bladed drum with an annular web, the ferromagnetic element being radially pressed against said web, or the rotor comprises two bladed discs, the ferromagnetic element forming a mechanical link between said discs. The ferromagnetic element is a first ferromagnetic element, the rotor comprising an annular row of ferromagnetic elements to which the first element belongs, said elements of the row being angularly separated and each associated with at least one magnet of the annular row of magnets. The compressor comprises an axial gap, the permanent magnets axially overlapping and / or axially passing through the axial gap. The turbomachine comprises a blower support bearing disposed inside the compressor and axially at the level of the annular row of coils.The rotor comprises an annular platform supporting an annular row of rotor blades. The annular row of magnets is arranged inside the annular platform, with the magnets in thermal conduction with the annular row of rotor blades. The electrical machine is reversible and / or synchronous. The ferromagnetic component(s) are arranged radially within the row of coils. The ferromagnetic component forms a mechanical connection within the rotor. The permanent magnets of the annular row contact the axial air gap(s). The annular row of coils is arranged axially between the first and second rows of magnets, particularly within the same electrical machine. The electrical machine comprises at least one or two axial air gaps. The coil, or annular row of coils, is arranged axially between these air gaps and receives an axial magnetic flux through them.The axial flux coil is located within the radial thickness of the internal support. The coil is axially shorter than the internal shell, and possibly shorter than the internal support. The coils have parallel and / or axially oriented winding axes. The sealing device includes sealing surfaces formed on an internal shell, particularly on the internal support, and on the ferromagnetic component. The electrical connections are located upstream of the blade to de-ice it.

[0010] This description also relates to a compressor, possibly an axial turbomachine, the compressor comprising a stator with an annular row of stator blades supporting an inner shell, a rotor mounted movable in rotation relative to the stator, a rotating electrical machine which has a row of coils supported by, and / or in thermal conduction with, the inner shell, and a row of permanent magnets carried by the rotor and cooperating magnetically with the coils.

[0011] The invention also relates to a method of compressing a compressible fluid by an axial turbomachine compressor remarkable in that the turbomachine is according to the invention, with at least one annular row of permanent magnets being attached to the rotor, and at least one annular row of coils being attached to the stator, the method comprising the following steps: (a) rotation of the rotor, in particular in contact with and / or by means of a turbine downstream of a combustion chamber of the turbomachine; and (b) generation of magnetic flux inside the coils, the coils being axially traversed by magnetic flux.

[0012] According to advantageous embodiments of the invention, the method may comprise one or more of the following features, taken individually or in all possible technical combinations: The turbomachine is an aircraft turbojet engine. During generation stage (b), the aircraft is in flight, the temperature of the magnets is below 0°C, and the temperature of the aircraft's environment is also below 0°C. During generation stage (b), the coils produce electrical current, which is stored in a battery. During generation stage (b), voltage differences are applied across the terminals of the electric coils to rotate the compressor rotor, possibly in conjunction with the turbine. During generation stage (b), the magnetic flux is generated axially by the magnets, which have axially opposite poles.

[0013] This description also relates to a method of producing electrical energy by an axial turbomachine electric machine comprising a compressor with a rotor and a stator having a rectifier, a turbine, an electric machine with a coil attached to the stator and a magnet attached to the rotor, the method comprising the following steps: (i) rotation of the rotor; (ii) production of electrical energy by the coil, and / or of a magnetic flux in a magnetic circuit of the rotating electric machine.

[0014] According to an advantageous mode, during the production step (ii), the magnetic flux passes axially through the compressor rectifier, and / or the magnetic flux passes axially through the inner shell of the compressor, and / or the process further includes a step (iii) supplying power to the coil in order to pivot the rotor. Benefits provided

[0015] The invention increases the compressor's electricity production capacity. Since the electric machine is reversible, the invention can increase the compression ratio. Furthermore, the position of the magnets within the compressor allows them to be cooled, thus reducing their temperature below their Curie point. The machine's safety is also improved. Brief description of the drawings

[0016] There figure 1 represents an axial turbomachine according to the invention. The figure 2 is a diagram of a turbomachine compressor according to the invention. figure 3 illustrates a rotating electrical machine according to the invention. figure 4 is a diagram of a fluid compression process according to the invention. Description of the implementation methods

[0017] In the following description, the terms "internal" and "external" refer to positioning relative to the axis of rotation of an axial turbomachine. The axial direction corresponds to the direction along the turbomachine's axis of rotation. The radial direction is perpendicular to the axis of rotation. Upstream and downstream refer to the main flow direction within the turbomachine.

[0018] There figure 1This simplified diagram represents an axial turbomachine. In this specific case, it is a turbofan engine. The turbofan engine 2 comprises a first compression stage, called the low-pressure compressor 4, a second compression stage, called the high-pressure compressor 6, a combustion chamber 8, and one or more turbine stages 10. During operation, the mechanical power of the turbine 10, transmitted via the central shaft to the rotor 12, sets the two compressors 4 and 6 in motion. These compressors have several rows of rotor blades associated with rows of stator blades. The rotation of the rotor around its axis of rotation 14 generates an airflow and progressively compresses this air until it enters the combustion chamber 8.

[0019] An inlet fan commonly referred to as a fan or blower 16 is coupled to the rotor 12 and generates an airflow which splits into a primary flow 18 passing through the aforementioned levels of the turbomachine, and a secondary flow 20 passing through an annular duct (partially shown) along the machine and then joining the primary flow at the turbine outlet.

[0020] Gear reduction devices, such as an epicyclic gearbox 21, can reduce the rotational speed of the fan and / or low-pressure compressor relative to the associated turbine. The secondary flow can be accelerated to generate the thrust necessary for the flight of a passenger aircraft. The primary flow 18 and secondary flow 20 are coaxial annular flows nested within each other.

[0021] There figure 2 is a cross-sectional view of a compressor in an axial turbomachine such as that of the figure 1The compressor can be a low-pressure compressor 4. Part of the blower 16 and the separation nozzle 22 of the primary flow 18 and the secondary flow 20 can be observed there. The rotor 12 comprises several rows of rotor blades 24, in this case three.

[0022] The low-pressure compressor 4 comprises several rectifiers, in this case four, each containing a row of stator vanes 26. Some of these stator vanes may have adjustable orientation, also known as variable-pitch vanes. Such vanes are commonly referred to as VSV vanes, the acronym for which stands for "Variable Stator Vane".

[0023] The stator blades 26 extend essentially radially from an external housing and can be fixed and secured there by means of pins. Within the same row, the stator blades 26 are regularly spaced from one another and have the same angular orientation in the flow. Advantageously, the blades in the same row are identical.

[0024] To produce electricity, the turbomachine may include one or more rotating electrical machines 30, for example in the compressor 4. In addition, the turbomachine may include an electrical accumulator 32, or battery, receiving and storing the electrical energy produced by the rotating machines 30. For this purpose, electrical connections 34 may cross the primary flow 18 and be supported by the stator blades 26. Optionally, at least one connection may be supported by the stator blades 26 at the inlet 36 of the compressor 4, i.e., at the level of the separation nozzle 22. Alternatively, the accumulator 32 is specific to the corresponding aircraft.

[0025] For example, at least one electrical machine 30 comprises an annular array of magnetic and / or electrical coils 38 that cooperate magnetically with an annular array of permanent magnets 40. The coils 38 are attached to the stator 42, and the permanent magnets 40 are attached to the rotor 12. For example, each coil 38 can receive the magnetic flux generated by the associated magnets 40. During the rotation of the rotor 12, the movement of the permanent magnets 40 past the coils 38 creates an electrical potential difference, thereby producing an electric current.

[0026] Each coil 38 can be formed from a winding of turns represented by an electrical wire. The winding axis can be axial, that is to say substantially along the axis of rotation 14.

[0027] The turbomachine may include a bearing 46 pivotally connecting the blower 16 to the stator 42. This bearing 46 may be located inside the rotor 12, and optionally at the level of one or more of the electrical machines 30. The compressor rotor 12 may also be articulated relative to the stator 42 by means of this bearing 46.

[0028] In the option where the rotor 12 forms a bladed drum, it may include openings for receiving the permanent magnets 40. Alternatively, the magnets may be placed in blind pockets. Such arrangements may be provided for a rotor formed by a series of discs.

[0029] There figure 3 Sketch a portion of the turbomachine with a rotating electrical machine 30. The portion may correspond to a part of the compressor. The compressor may be similar or identical to the one in figure 2 Similarly, the rotating electrical machine 30 can correspond to one of those shown in figure 2 The rotor 12 is here in an angular position where two magnets 40 are opposite the coil 38.

[0030] The component may at least represent a compression stage. This may be a rectifier 48. The row of stator blades 26 may support an internal cantilevered ferrule 50. The latter may be connected to the inner ends of the stator blades 26. At least one or each of the stator blades 26 has a leading edge. Electrical connections 34 may be placed axially at the leading edges to defrost the corresponding blade, the electrical connections being specifically designed to heat up by Joule heating when the coils receive or generate electric current.

[0031] The inner shell 50 includes an outer wall 52 of annular shape, delimiting the interior of the primary flux 18. Optionally, the inner shell 50 includes an internal support 54, for example, of annular shape. This internal support 54 can be separated from the stator blades 26 by the outer wall 52, so that the coil 38 can be isolated from the primary flux 18 by the wall 52 and, in particular, by the support 54.

[0032] The compressor may include at least one sealing device 56. The sealing device 56 may be around the electrical machine 30, and / or inside the electrical machine 30. One of the sealing devices 56, possibly external, may be provided between the wall 52 of the shell 50 and a platform 58 receiving a row of rotor blades 24. Such a sealing device 56 may include a brush seal 61, for example between the wall 52 and the platforms 58. At least one sealing device 56, for example a brush seal 61, may surround the rotating electrical machine 30. Thus, the machine 30 is protected from the primary flow 18.

[0033] One of the sealing devices 56 may include licks 60, also called annular teeth, cooperating in a hermetic manner with the internal support 54.

[0034] At least one or each coil 38 of the annular row may include a magnetic core 62. Each magnetic core 62 may pass axially through the associated coil and may optionally be axially aligned with the opposing magnets 40 upstream and downstream. The core(s) 62 may be housed in the support 54.

[0035] The cores 62 can define at least one, preferably two, air gaps 64, in particular an upstream air gap 64 and a downstream air gap 64. Each air gap 64 can be an axial air gap, and can be provided axially between one of the magnets 40 and the core 62 or the coil 38. Each air gap 64 can be axially between one of the magnets 40 and the support 54. The air gaps 64 and the support 54, respectively the coil and / or the core, occupy an axial distance E between the permanent magnets 40. This axial distance E is shorter axially than the outer wall 52 of the shell 50 and / or than the stator blades 26. The coil 38 can be flat. The axial position of the permanent magnets 40 is such that they are at a distance from the rotor blades 24 and / or the drum web 58. Thus, there is no axial overlap between the rotor blades 24 and the magnets 40 or between the web 58 and the magnets 40.

[0036] The electric machine 30 may include a ferromagnetic part 66, or optionally an annular row of angularly separated and distinct ferromagnetic parts 66. The ferromagnetic part or parts 66 may be carried by the rotor 12, and / or may have a U-shaped form. The ferromagnetic part or parts 66 may be associated with, and in contact with, at least one magnet 40, or two magnets 40.

[0037] Each ferromagnetic part 66 may have at least one radial portion 68, or two radial portions 68; and optionally an axial portion 70, which may connect the radial portions 68. The latter may be in contact with the magnets 40. The sealing device 56, in particular the tabs 60, may be formed on the axial portion 70. This may extend over the entire axial length of the coil(s) 38. The radial portions 68 may be arranged upstream and downstream of the coil 38, and may extend radially further inwards.

[0038] Depending on the angular position of the rotor 12, the ferromagnetic part 66 can frame the coil 38, notably to define a magnetic circuit 72. Such a magnetic circuit 72 can pass axially through the coil thanks to its magnetic field lines 74 describing a loop that passes through the air gaps 64. Inside the coil 38 and the magnets 40, the magnetic field lines 74 are primarily axial. Their inclination with respect to the axis of rotation is less than 25° or 10°.

[0039] Although only one coil 38, one part 66, one stator blade 26, only two magnets 40 are represented and described, the present teaching can be applied to each of the annular rows to which they belong.

[0040] The stator 42 and the rotor 12 may have an axial clearance 76 at one of their interfaces. The axial clearance 76 may be circular. For example, the axial clearance may be provided between a platform 78 and the inner shell 50, in particular between a platform 78 and the annular wall 52. The axial clearance 76 may be closed by a sealing device 56, in particular a brush seal 61. Magnets 40 may extend axially at the axial clearance 76, and optionally pass through the axial clearance 76.

[0041] There figure 4 represents a diagram of a compression process, for example primary flow, in a turbomachine compressor. Both the compressor and the turbomachine can correspond to those described in relation to the figures 1 to 3 .

[0042] The process may include the following steps, possibly carried out in the following order: (a) rotation 100 of the rotor in contact with the turbine receiving the flow from the combustion chamber; (b) generation 102 of magnetic flux inside the coils.

[0043] The invention is applicable to the field of aeronautics. Thus, the turbomachine can correspond to a turbojet engine for an aircraft flying at a negative temperature, for example, -40°C at altitude. During step (b), generation 102, the aircraft is in flight and the temperature of the magnets is below 0°C. The coils, and possibly the cores, can be cooled by the stator blades.

[0044] During step (b) generation 102, each coil has an electrical voltage difference across its terminals.

[0045] The rotating electric machine can operate in two modes. It can either be a generator of electrical current and voltage, or an electric motor that drives the compressor rotor to contribute to the mechanical effort of compressing the primary flow. Thus, during generation stage (b), the coils either produce electrical current stored in a battery or receive electrical current from the battery to rotate the compressor rotor. The compressor can operate in a hybrid mode, as its drive can be provided by the electric machine in addition to the turbine. The turbomachine design can incorporate this hybrid operating mode, also called mixed operation, and reduce the peak loads imposed on the turbine.

Claims

1. Axial turbomachine (2), notably an aircraft turbojet engine, the turbomachine (2) comprising a compressor (4; 6) with a rotor (12) and a stator (42), a turbine (10), a combustion chamber (8) axially between the compressor (4; 6) and the turbine (10), and a rotating electrical machine (30) rotationally coupled to the compressor (4; 6), the compressor (4; 6) comprising an inner shroud (50) supporting a row of stator blades (26) extending radially outwardly from the inner shroud (50), such that the inner shroud (50) comprises a wall (52) radially external with respect to the rotating electrical machine (30) and defining a primary vein of the compressor (4; 6), the rotating electrical machine (30) being with axial magnetic flux and comprising an annular row of axial magnetic flux coils (38), a first annular row of axial magnetic flux permanent magnets (40), characterized in that it comprises a second annular row of axial flux permanent magnets (40), and an axial gap (E) between the first row of magnets (40) and the second row of magnets (40), said axial gap (E) being axially shorter than the external wall (52) of the shroud (50) and / or than the stator blades (26), the annular row of coils (38) occupies the axial gap (E), the coils (38) are integral with the stator (42), and the permanent magnets (40) are integral with the rotor (12).

2. Axial turbomachine (2) according to claim 1, characterized in that the inner shroud (50) has a radial thickness within which the annular row of coils (38) is radially disposed.

3. Axial turbomachine (2) according to claim 2, characterized in that the inner shroud (50) comprises the external wall (52) defining a primary vein of the compressor (4; 6) and an internal support (54) within which the annular row of coils (38) or at least one coil (38) is disposed, the internal support (54) being axially shorter than the external wall (52).

4. Axial turbomachine (2) according to one of claims 1 to 3, characterized in that at least one or each coil (38) of the annular row of coils comprises a magnetic core (62) axially passing through the corresponding coil (38).

5. Axial turbomachine (2) according to one of claims 1 to 4, characterized in that the compressor (4; 6) comprises a sealing device (56) in the radial thickness of the rotating electrical machine (30) in order to ensure sealing between the rotor (12) and the stator (42).

6. Axial turbomachine (2) according to one of claims 1 to 5, characterized in that the compressor (4; 6) comprises an upstream intake (36), the annular row of magnets (40) and / or the annular row of coils (38) being axially disposed at the upstream intake (36).

7. Axial turbomachine (2) according to one of claims 1 to 6, characterized in that the rotor (12) comprises a main body with a first material, notably a non-magnetic material, and a ferromagnetic part (66) in magnetic contact with the annular row of permanent magnets (40).

8. Axial turbomachine (2) according to claim 7, characterized in that the ferromagnetic part (66) is capable of forming a magnetic circuit (72) in combination with one of the coils (38), said magnetic circuit (72) axially traversing the coil (38), the ferromagnetic part (66) comprising an axial portion (70) between two radial portions (68).

9. Axial turbomachine (2) according to one of claims 7 to 8, characterized in that the rotor (12) comprises a bladed drum with an annular web, the ferromagnetic part (66) being radially pressed against the web, or the rotor (12) comprises two bladed discs, the ferromagnetic part (66) forming a mechanical connection between the discs.

10. Axial turbomachine (2) according to one of claims 1 to 9, characterized in that the compressor comprises an axial gap (76), the permanent magnets (40) axially overlapping and / or axially traversing the axial gap (76).

11. Axial turbomachine (2) according to one of claims 1 to 10, characterized in that it comprises a bearing (46) supporting a blower (16) disposed inside the compressor (4; 6) and axially at the level of the annular row of coils (38).

12. Axial turbomachine (2) according to one of claims 1 to 11, characterized in that the rotor (12) comprises an annular platform (58) supporting an annular row of rotor blades (24), the annular row of magnets (40) being disposed inside the annular platform (58), the magnets (40) being in thermal conduction with the annular row of rotor blades (24).

13. Method for compressing a compressible fluid by a compressor (4; 6) of an axial turbomachine (2) characterized in that the turbomachine is according to one of claims 1 to 12, at least one annular row of permanent magnets (40) being integral with the rotor (12), and at least one annular row of coils (38) being integral with the stator (42), the method comprising the following steps: (a) rotating (100) the rotor (12) engaged with a turbine (10) downstream of a combustion chamber (8) of the turbomachine (2); and (b) generating (102) magnetic flux inside the coils (38), the coils (38) being axially traversed by magnetic flux.

14. Method according to claim 13, characterized in that the turbomachine (2) is an aircraft turbojet engine, during step (b), generating (102) while the aircraft is in flight, and the temperature of the magnets (40) is below 0°C, and the environmental temperature of the aircraft is below 0°C.

15. Method according to one of claims 13 or 14, characterized in that during step (b) generation (102), the coils (38) produce electric current stored in an accumulator (32) and / or electric voltage differences are applied to the terminals of the coils (38) in order to rotate the rotor (12) of the compressor (4; 6), possibly in combination with the turbine (10).