Decoupling device for an aircraft turbine engine

Abstract

The invention relates to a decoupling device (5, 5, 5) for an aircraft turbine engine (T), the aircraft turbine engine (T) comprising a transmission line (2) connected to a shaft (Abp) of the turbine engine (T), and comprising an electric machine (1) connected to the transmission line (2), the decoupling device (5, 5, 5) comprising flexible torsional decoupling means (50, 50, 50) and comprising a casing that comprises two flanges (51, 51, 52, 52), the flexible torsional decoupling means (50, 50, 50) being at least partly enclosed inside the casing, a first of the two flanges (51, 51) being configured to be connected to the transmission line (2), a second of the two flanges (52) being configured to be connected to the electric machine (1), the first and second flanges (51, 52) being movable relative to one another and being connected to one another via the flexible torsional decoupling means (50).

Description

[0001] DESCRIPTION

[0002] TITLE: DECOUPLIZING DEVICE FOR AIRCRAFT TURBOMACHINE.

[0003] Scope of the invention

[0004] The present invention relates to the field of aircraft turbomachinery.

[0005] More specifically, the invention relates to hybrid aircraft turbomachines, for example to twin-body turbomachines, and concerns a decoupling device for such an aircraft turbomachine.

[0006] The invention is particularly advantageous for an electric machine connected to a propulsion shaft of an aircraft turbomachine via a kinematic chain, this electric machine being configured to operate in a motor mode to drive the propulsion shaft in rotation or in a generator mode to generate electrical energy.

[0007] Prior art

[0008] Climate change is a major concern for many legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by different countries. In particular, an ambitious standard applies to both new types of aircraft and those already in service, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively working for several years now to contribute to the fight against climate change.

[0009] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into account the factors impacting all phases of design and development in order to obtain aeronautical components and products that are less energy-intensive, more environmentally friendly, and whose integration and use in civil aviation have moderate environmental consequences, with the aim of improving the energy efficiency of aircraft.

[0010] Consequently, the Applicant is constantly working to reduce its negative climate impact by using methods and operating virtuous development and manufacturing processes that minimize greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0011] This sustained research and development work focuses on new generations of aircraft engines, the weight reduction of aircraft, particularly through the materials used and lighter on-board equipment, the development of the use of electrical technologies to provide propulsion, and, as essential complements to technological progress, aviation biofuels.

[0012] Figure 1 shows an aircraft turbomachine T comprising a fan 100, a low-pressure compressor 101, a high-pressure compressor 102, a high-pressure turbine 103, and a low-pressure turbine 104. A low-pressure shaft Abp connects the low-pressure compressor 101 to the low-pressure turbine. A high-pressure shaft Ahp connects the high-pressure compressor 102 to the high-pressure turbine 103. A fan 100 is mounted integrally with the low-pressure shaft Abp.

[0013] It is known in the prior art to mount an electric machine on the propulsion shaft of an aircraft turbomachine, such as a fan shaft, to create a hybrid turbomachine. The electric machine is typically configured to operate in generator mode, drawing mechanical power from the propulsion shaft to generate electrical power. The electric machine is also configured to operate in motor mode, providing mechanical power to the propulsion shaft by drawing electrical power, for example, from a battery.

[0014] With reference to Figure 1, it has been proposed to connect the electric machine 1 to a drive shaft of the turbomachine Ahp by means of a transmission line 2, or kinematic chain, comprising an internal gearbox 21 known by its English designation "IGB" for "Internal Gear Box", a radial drive shaft 22 known by its English designation "RDS" for "Radial Drive Shaft", and an accessory gearbox 23 known by its English designation "AGB" for "Accessory Gear Box". As is known, the electric machine 1 comprises a stator 11 and a rotor 12 configured to interact magnetically with the stator 11.

[0015] In practice, during the operation of the electric machine 1 in motor or generator mode, a torsional mode Mt is likely to appear in the transmission line 2. A torsional mode Mt corresponds in particular to an oscillation of torque and speed at a torsional frequency. The torsional mode Mt can manifest itself, for example, as a torsion of the radial transmission shaft 22.

[0016] Even though the frequency and amplitude of these oscillations depend on the damping factor and vary according to the torque applied to the transmission line 2, this frequency remains relatively close to the natural torsional frequency of the drive train. Furthermore, it appears that even when the electric machine 1 is uncontrolled, torque oscillations can persist in the transmission line 2 and are also relatively close to the natural torsional frequency of the transmission line 2.

[0017] These oscillations at a frequency close to the torsional natural frequency may be a response to an excitation source of the same frequency, the origin of which is not necessarily known. This initial coupling between the torsional natural frequency of the transmission line 2 and the frequency of the excitation source can cause significant torsional vibration amplitudes due to the very low torsional damping of the transmission line 2, which can lead to premature wear of the transmission line 2 components or the electrical machine 1, or even failure of these components.

[0018] Furthermore, these vibrational pulsations are amplified by the machine's control system. When the electric machine is driven, the torque pulsations generate speed pulsations that are transmitted to the current loop. The disturbance is thus fed back to the electric machine's torque control, amplifying the phenomenon. The electric machine also becomes an excitation source that amplifies and sustains the pulsations resulting from the initial coupling.

[0019] There is therefore a need to provide a solution to address the problem of coupling between the natural torsional frequency of the transmission line and the frequency of an excitatory source of the same frequency, the origin of this excitatory source not necessarily being identified.

[0020] Description of the invention

[0021] The invention aims to remedy at least in part the aforementioned drawbacks relating to prior art techniques.

[0022] To this end, the invention relates to a decoupling device for an aircraft turbomachine, said aircraft turbomachine comprising a transmission line connected to a shaft of said turbomachine, and comprising an electric machine connected to said transmission line, said decoupling device comprising torsionally flexible decoupling means and comprising a housing having two flanges, the torsionally flexible decoupling means being at least partly enclosed inside the housing, a first of said two flanges being configured to be connected to said transmission line, a second of said two flanges being configured to be connected to said electric machine, said first and second flanges being movable relative to each other and being connected to each other by means of said torsionally flexible decoupling means.

[0023] Thus, the solution provides a way to address the problem of coupling between the natural frequency of torsion of the transmission line and the frequency of an excitation source whose origin is not necessarily known, and indirectly to lower the amplitude of the pulsations in vibration amplified by the regulation of the machine.

[0024] Indeed, by implementing two flanges that move relative to each other, each connected to one of the transmission line and the electrical machine, it is possible to lower the torsional frequency of the kinematic chain and thus eliminate the coupling between the natural torsional frequency of the transmission line and the frequency of the excitation from an excitation source, by modifying the natural torsional frequency of the transmission line.

[0025] This decoupling device is a compact, non-dissipative component for lowering the torsional frequency of the drivetrain. Advantageously, this eliminates the need for dissipative components specifically designed to modify the damping factor, as such components require additional maintenance.

[0026] The first flange and the second flange are movable relative to each other along at least two axes of translation.

[0027] They can also, in order to allow a margin of tolerance and avoid a break in the decoupling device, be movable relative to each other along a third axis of translation so that they can move away from each other, and can also be movable relative to each other along one or more axes of rotation.

[0028] According to a particular aspect of at least one embodiment of the invention, said transmission line comprises an internal transmission housing configured to be connected to a shaft of said turbomachine, a radial transmission shaft, and an accessory relay housing, said first of said two flanges being configured to be connected to said accessory relay housing. According to a particular aspect of at least one embodiment of the invention, said torsionally flexible decoupling means comprise a flexible membrane configured to be formed around a longitudinal axis X of said electric machine and connected to said two flanges.

[0029] According to a particular aspect of at least one embodiment of the invention, this flexible membrane is circular.

[0030] According to a particular aspect of at least one embodiment of the invention, said flexible membrane is made at least partially from steel.

[0031] According to a particular aspect of at least one embodiment of the invention, said flexible membrane has a plurality of radial cutouts extending from a center of said flexible membrane.

[0032] According to a particular aspect of at least one embodiment of the invention, said flexible membrane has a tensile flexibility at the outer periphery which is less than a tensile flexibility at the center.

[0033] According to a particular aspect of at least one embodiment of the invention, said two flanges have an external perimeter of substantially circular shape.

[0034] According to a particular aspect of at least one embodiment of the invention, the decoupling device has a circumferential groove formed on at least one of the two flanges in the vicinity of said outer periphery of said at least one of the two flanges. Furthermore, said torsionally flexible decoupling means comprise at least one spring housed in said circumferential groove so as to extend circumferentially relative to said decoupling device.

[0035] According to a particular aspect of at least one embodiment of the invention, said at least one spring is made from a metallic material by additive manufacturing.

[0036] According to a particular aspect of at least one embodiment of the invention, said at least one spring is dimensioned to achieve a torsional frequency of less than 120Hz, preferably between 20 and 40Hz.

[0037] According to a particular aspect of at least one embodiment of the invention, said circumferential groove is formed only on one of the two flanges in the vicinity of said outer periphery of said one of the two flanges. Furthermore, the other of said two flanges has a circular crown shape configured to axially cover said circumferential groove.

[0038] The invention also relates to an aircraft turbomachine comprising a transmission line and an electrical machine connected to said transmission line, and a decoupling device according to one of the aforementioned embodiments, a first of said two flanges being connected to said transmission line, a second of said two flanges being connected to said electrical machine, said first and second flanges being movable relative to each other and being connected to each other by means of said torsionally flexible decoupling means.

[0039] Presentation of the figures

[0040] The invention, and its various advantages, will be more easily understood in light of the following description of several illustrative and non-limiting embodiments thereof, and the accompanying drawings, among which:

[0041] [Fig. 1] is a schematic view of a portion of an aircraft turbomachine according to the prior art; [Fig. 2] is a schematic view of a portion of an aircraft turbomachine according to an example of the invention;

[0042] [Fig. 3A] and [Fig. 3B] are two schematic cross-sectional views of a portion of an aircraft turbomachine, illustrating the decoupling device according to a first embodiment;

[0043] [Fig. 4] is a schematic cross-sectional view of a decoupling device according to a second embodiment, and

[0044] [Fig. 5A] and [Fig. 5B] are two schematic views respectively in perspective and exploded perspective of a decoupling device according to a third embodiment.

[0045] Detailed description of an embodiment of the invention

[0046] With reference to Figure 2, an aircraft turbomachine T is shown comprising a low-pressure compressor 101, a high-pressure compressor 102, a high-pressure turbine 103, and a low-pressure turbine 104. A low-pressure shaft Abp connects the low-pressure compressor 101 to the low-pressure turbine 104. A high-pressure shaft Ahp connects the high-pressure compressor 102 to the high-pressure turbine 103. A fan 100 is mounted integrally with the low-pressure shaft Abp. The aircraft turbomachine T includes a combustion chamber (not shown) for consuming a mixture of fuel and a pressurized airflow accelerated by the compressors 101 and 102. An exhaust flow drives the turbines 103 and 104. Both the high-pressure shaft Ahp and the low-pressure shaft Abp are propulsion shafts. The architecture of such a T aircraft turbomachine is known to those skilled in the art and will not be presented in further detail.

[0047] In this example, the aircraft turbomachine T is hybrid and includes an electric machine 1 connected to the high-pressure shaft Ahp by a transmission line 2 configured to transmit a mechanical torque between the high-pressure shaft Ahp and the electric machine 1. It is nevertheless understood that the invention also applies to an electric machine 1 connected to the low-pressure shaft Abp by a transmission line 2.

[0048] In this example, with reference to Figure 2, the transmission line 2 preferably comprises successively from the high-pressure shaft Ahp to the electric machine 1: an internal transmission box 21, known by its English designation "IGB" for "Internal Gear Box"; a radial drive shaft 22, known by its English designation "RDS" for "Radial Drive Shaft"; an accessory relay box 23, known by its English designation "AGB" for "Accessory Gear Box", and an adapter box (not shown in the figures), known by its English designation "GBX" for "GearBox".

[0049] The internal transmission housing 21 contains gears and is housed as close as possible to the high-pressure shaft Ahp to enable power transmission / receipt.

[0050] The radial drive shaft 22 preferably extends in a radial arm of the turbomachine T in order to cross a stream of air accelerated by the blower 100. The radial drive shaft 22 has a degree of flexibility and is particularly sensitive to a torsion mode Mt.

[0051] The accessory relay box 23 has a plurality of gears to receive various accessories such as a starter or a lubrication device.

[0052] According to the invention, the aircraft turbomachine T further comprises a decoupling device. This decoupling device includes a housing consisting of two flanges and torsionally flexible decoupling means at least partially enclosed within this housing. More specifically, one of the two flanges is configured to be connected to the transmission line 2, while the other of the two flanges is configured to be connected to the electric machine. These two flanges are movable relative to each other and are connected to each other by means of the torsionally flexible decoupling means.

[0053] Several embodiments of the invention are subsequently presented by way of illustration and not limitation. In all the embodiments presented, the first of the two flanges is configured to be connected to the transmission line on the shaft side of the turbomachine, preferably configured to be connected to the accessory relay box.

[0054] A first embodiment of the invention is then presented in relation to figures 3A and 3B.

[0055] As illustrated, in this embodiment, the decoupling device 5 includes torsionally flexible decoupling means 50 in the form of a flexible membrane 50, which is here a flexible circular membrane, configured to be formed around a longitudinal axis X of the electrical machine 1, this flexible circular membrane 50 being at least partly enclosed inside a housing made up of two flanges 51, 52, the flexible circular membrane being connected to the two flanges.

[0056] The membrane can, for example, be connected to the two flanges at the edges of each flange, or can also be fixed to each of the flanges at points distributed over the surface of the membrane.

[0057] In this embodiment, these two flanges 51, 52 have an external perimeter of substantially circular shape.

[0058] According to variations of this embodiment, the two flanges can take other forms without departing from the scope of the invention.

[0059] More particularly, in this embodiment, a first 51 of the two flanges is configured to be connected to the transmission line 2, while a second of the two flanges 52 is configured to be connected to the electrical machine 1. These two flanges 51, 52 are movable relative to each other and are connected to each other by means of the torsionally flexible decoupling means 50, i.e., the flexible circular membrane 50.

[0060] Here, the flexible circular membrane 50 is made at least partially from steel. More precisely, the density of steel in the composition is heterogeneous such that the membrane exhibits a tensile flexibility at the outer perimeter that is less than its tensile flexibility at the center.

[0061] This flexible circular membrane 50 is designed to achieve a torsional frequency below 120 Hz, preferably between 20 and 40 Hz. More precisely, this flexible circular membrane 50 is designed so that the ratio between its stiffness (measured in Nm / rad) and its inertia (measured in kg.m) 2 ) of the electrical machine is preferably between 6xl0 5 and 1.6xl0 5 and greater than 1.8xl0 6 .

[0062] A second embodiment of the invention is subsequently presented in relation to Figure 4. In this embodiment, the two flanges are identical to the two flanges of the first embodiment.

[0063] The difference between the first embodiment and this second embodiment lies in the fact that the decoupling device 5' according to this second embodiment comprises torsionally flexible decoupling means 50' in the form of a flexible circular membrane 50' which has a plurality of radial cutouts 500 extending from a center of the flexible circular membrane 50'.

[0064] More specifically, these radial cutouts 500 extend radially, widening outwards so that they have a substantially triangular shape.

[0065] The cutouts can be circumferentially uniformly distributed around the longitudinal axis X.

[0066] Here, and as in the first embodiment, the 50' flexible circular membrane is made at least partially from steel.

[0067] More specifically, the steel density in the composition is heterogeneous over the extent of the membrane such that the membrane exhibits a tensile flexibility at the outer perimeter 501 which is less than a tensile flexibility at the center 502.

[0068] A third embodiment of the invention is then presented in relation to figures 5A and 5B.

[0069] As illustrated, in this embodiment, the decoupling device 5" has a circumferential groove 53 formed on at least one of the two flanges 51', 52' and more particularly in the vicinity of the outer perimeter of at least one of the two flanges 51', 52'.

[0070] More specifically, here the circumferential groove 53 is formed only on one of the two flanges 51' in the vicinity of the outer perimeter of one of the two flanges 51', while the other of the two flanges 52' has a circular crown shape configured to axially cover the circumferential groove 53.

[0071] Here, more specifically, the circumferential groove 53 is formed on one of the two flanges 51' while the other flange 52' has a deformation configured to come opposite this groove.

[0072] In this third embodiment, the torsionally flexible decoupling means 50" comprise a plurality of springs 54 housed in the circumferential groove 53 so as to extend circumferentially with respect to the decoupling device 5". In other words, the torsionally flexible decoupling means 50" comprise a plurality of springs 54 placed end to end in the circumferential groove 53 formed on at least a part of the circumference of one of the two flanges.

[0073] According to other alternatives, the torsionally flexible decoupling means include at least one spring housed in the circumferential groove so as to extend over a circumference of at least one of the flanges.

[0074] The springs here are made from a metallic material using additive manufacturing.

Claims

DEMANDS

1. Decoupling device (5, 5', 5") for aircraft turbomachine (T), said aircraft turbomachine (T) comprising a transmission line (2) connected to a shaft (ABP) of said turbomachine (T), and comprising an electric machine (1) connected to said transmission line (2), said decoupling device (5, 5', 5") comprising torsionally flexible decoupling means (50, 50', 50") and comprising a housing having two flanges (51, 51', 52, 52'), the torsionally flexible decoupling means (50, 50', 50") being at least partially enclosed within the housing, a first of said two flanges (51, 51') being configured to be connected to said transmission line (2), a second of said two flanges (52) being configured to be connected to said electric machine (1), said first and second flanges (51, 52) being movable relative to each other and being connected to each other by means of said torsionally flexible decoupling means (50,50', 50").,

2. Decoupling device (5, 5', 5") according to claim 1, characterized in that said transmission line (2) comprises an internal transmission housing (21) configured to be connected to a shaft of said turbomachine (T), a radial transmission shaft (22), and an accessory relay housing (23), said first of said two flanges (51, 51', 52, 52') being configured to be connected to said accessory relay housing (23).

3. Decoupling device (5, 5') according to claim 1 or 2, characterized in that said torsionally flexible decoupling means (50, 50') comprise a flexible membrane (50) configured to be formed around a longitudinal axis (X) of said electrical machine (1) and connected to said two flanges (51, 52).

4. Decoupling device (5, 5') according to the preceding claim, characterized in that said flexible membrane (50, 50') is made at least partially from steel.

5. Decoupling device (5') according to any one of claims 3 or 4, characterized in that said flexible membrane (50') has a plurality of radial cutouts (500) extending from a center of said flexible membrane (50').

6. Decoupling device (5, 5') according to any one of claims 3 to 5, characterized in that said flexible membrane (50, 50') has a tensile flexibility at the outer periphery which is less than a tensile flexibility at the center.

7. Decoupling device (5") according to any one of the preceding claims, characterized in that it has a circumferential groove (53) formed on at least one of the two flanges (51', 52') in the vicinity of said outer periphery of said at least one of the two flanges (51', 52'), and in that said torsionally flexible decoupling means (50") comprise at least one spring (54) housed in said circumferential groove (53) so as to extend circumferentially with respect to said decoupling device (5").

8. Decoupling device (5") according to claim 7, characterized in that said circumferential groove (53) is formed only on one of the two flanges (51', 52') in the vicinity of said outer perimeter of said one of the two flanges (51'), and in that the other of said two flanges (52') has a circular crown shape configured to axially cover said circumferential groove (53).

9. Aircraft turbomachine comprising a transmission line (2) and an electrical machine (1) connected to said transmission line (2), characterized in that it comprises a decoupling device (5, 5', 5") according to any one of claims 1 to 8, a first of said two flanges (51, 51') being connected to said transmission line (2), a second of said two flanges (52) being connected to said electrical machine (1), said first and second flanges (51, 52) being movable relative to each other and being connected to each other by means of said torsionally flexible decoupling means (50).

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