AIRCRAFT TURBOMACHINE COMPRISING A MECHANICAL REDUCER DECOUNCEMENT DEVICE.

Abstract

The invention relates to a turbomachine (10) with a longitudinal axis (X) comprising a gas generator (11) and a blower (12) located upstream of the gas generator, said blower (12) being connected to a blower shaft (18) driven by a gas generator shaft (16) via a speed reducer (20), characterized in that said turbomachine (10) further comprises a mechanical decoupling device (9) configured to decouple said reducer (20) from said gas generator shaft (16) following a critical event causing axial displacement of said blower (12) towards said gas generator (11). Figure 3

Description

Title of the invention: AIRCRAFT TURBOMACHINE COMPRISING A MECHANICAL DECOUPANCEMENT DEVICE FOR THE REDUCER. Scope of the invention

[0001] The present invention relates to the field of turbomachinery, and more particularly to the field of aircraft turbomachinery.

[0002] More particularly, the invention relates to the implementation of a decoupling device for the reducer with respect to the gas generator so as to decouple the blower from the gas generator.

[0003] The invention applies more particularly to any type of aeronautical turbomachine, and especially to aircraft turbomachines such as turbojets and turboprops. Prior art

[0004] The state of the art includes, in particular, document WO 2018 115 763 AL

[0005] Conventionally, a turbomachine comprises a gas generator and a blower located at one end of the gas generator. The blower is intended to generate an airflow, at least part of which feeds the gas generator and forms a primary flow.

[0006] The gas generator comprises, from upstream to downstream in the direction of gas flow, at least one compressor, one combustion chamber, and one turbine. The role of the compressor is to compress air drawn in through an air inlet in order to increase the pressure of the air supplied to the combustion chamber. The air is then introduced into the combustion chamber where it is mixed with a fuel and burned. Next, the combustion gases pass through one or more turbines whose role is to drive the compressor by extracting some of the pressure energy from the hot gases exiting the combustion chamber and converting it into mechanical energy via a gas generator shaft.

[0007] Upstream of the compressor(s) is a blower designed to supply both a primary flow passing through the compressor and a secondary flow. The blower is driven in rotation by a blower shaft which may itself be driven by the gas generator shaft and generally rotates at the same speed if the blower shaft and the gas generator shaft are directly connected to each other.

[0008] However, it may be advantageous to rotate the blower at a lower rotational speed than the gas generator shaft, particularly when the latter is very large, in order to better adapt it aerodynamically. For This involves incorporating a reducer, otherwise known as a speed reduction device, between the blower shaft carrying the blower and the gas generator shaft.

[0009] Within the turbomachine, and in particular in relation to the blower, several axial retaining bearings are used.

[0010] These axial retaining bearings prevent the blower shaft from moving axially. This protects the gas generator by ensuring that the rotating components remain in their optimal operating position. Furthermore, these axial retaining bearings support axial loads and, in some cases, radial loads to ensure stable blower operation. Thus, by maintaining the proper alignment of the blower shaft, the axial retaining bearings help reduce wear on internal components caused by vibration or improper loads.

[0011] In addition, these same axial retaining bearings also participate in taking up radial loads by also guiding the blower shaft in the radial direction in addition to the axial direction.

[0012] These bearings are therefore crucial for the proper functioning and durability of the turbomachine by ensuring maximum efficiency and minimizing the risks of mechanical failure.

[0013] However, such axial retaining bearings can wear or break for several reasons, and in particular, over time and with use, micro-cracks can appear on the raceway surfaces, which can lead to material spalling and failure. Excessive vibration can also cause fatigue of the bearing materials. It is important to prevent material fatigue from causing cracks or breaks that could ultimately lead to bearing failure. Contamination by particles entering the axial retaining bearing can also cause deterioration of the axial retaining bearing.

[0014] A failure of an axial retaining bearing of the blower, in addition to the risks of bearing fragments that could damage other components of the turbomachine, could cause an axial misalignment of the blower and lead to axial displacement of the blower shaft line upstream of the engine, thus causing risks to the integrity of the turbomachine.

[0015] There is therefore a need to provide a solution that resolves at least some of these drawbacks listed above. Description of the invention

[0016] To this end, the invention relates to a longitudinal X-axis turbomachine comprising a gas generator and a blower located upstream of the generator gas, said blower being connected to a blower shaft driven by a gas generator shaft via a speed reducer. According to the invention, said turbomachine further comprises a mechanical decoupling device configured to decouple said reducer from said gas generator shaft following a critical event causing axial displacement of said blower towards said gas generator.

[0017] Thus, the proposed solution offers a novel and inventive approach that at least partially overcomes some of the drawbacks of the prior art. In particular, by decoupling the gearbox from the gas generator shaft following a critical event causing axial displacement of the fan towards the gas generator, an overspeed is generated at the gas generator shaft because it is no longer slowed in rotation by the fan's inertia. This automatically triggers the turbomachine control system to detect an engine problem and thus shuts down the gas generator without requiring any intervention from the aircraft pilot.

[0018] Such a solution therefore presents an advantage in terms of risks of serious damage to the turbomachine and aircraft safety.

[0019] According to a particular aspect of at least one embodiment of the invention, said reducer comprises an inlet ferrule mechanically connected to said gas generator shaft, and said mechanical decoupling device comprises at least one cutting head configured to move between: - a normal operating condition of said turbomachine in which said cutting head is separated from said inlet ferrule by a non-zero axial clearance in a normal operating position of said turbomachine, and - an operating situation of said turbomachine in which a critical event occurs, said cutting head coming into contact with said inlet ferrule so as to mechanically decouple said reducer of said gas generator shaft by cutting said inlet ferrule.

[0020] According to a particular aspect of at least one embodiment of the invention, in said normal operating situation, said axial play is between 0.3mm and 1mm.

[0021] This allows for a device that provides a margin of tolerance in case of axial displacement of the blower relative to the gas generator due to vibrations or distortions following variations in pressure or temperature.

[0022] According to a particular aspect of at least one embodiment of the invention, said mechanical decoupling device is fixed to a stator of said reducer, mounted movable in translation relative to said gas generator.

[0023] According to a particular aspect of at least one embodiment of the invention, said cutting head comprises a downstream end having a triangular shape with an apex oriented axially towards said inlet ferrule.

[0024] This makes it easier to cut the said inlet ferrule.

[0025] According to a particular aspect of at least one embodiment of the invention, the gas generator shaft includes a low pressure turbine shaft line of the turbomachine, the inlet ferrule being connected to a second ferrule which is itself connected to the low pressure turbine shaft line.

[0026] According to a particular aspect of at least one embodiment of the invention, the mechanical decoupling device is made at least partially from a material among steels / titaniums.

[0027] According to a particular aspect of at least one embodiment of the invention, said mechanical decoupling device has a flexibility of between 1.0E-9 and 3.0E-7 m / N

[0028] According to a particular aspect of at least one embodiment of the invention, said cutting head is made from a material among steels / titaniums.

[0029] According to a particular aspect of at least one embodiment of the invention, the cutting head is made at least partially from a material among the carbides.

[0030] Such rigidity thus makes it possible to resist resistance forces during decoupling.

[0031] According to a particular aspect of at least one embodiment of the invention, said mechanical decoupling device comprises a plurality of cutting heads circumferentially distributed uniformly around the X axis of the turbomachine and extending radially inwards.

[0032] This can help to balance the decoupling forces on the circumference of the mechanical decoupling device.

[0033] According to a particular aspect of at least one embodiment of the invention, said critical event belongs to the list including wear or breakage of an axial retaining bearing of the reducer.

[0034] The invention also relates to an aircraft comprising at least one turbomachine according to one of the aforementioned embodiments.

[0035] The invention also relates to a method for managing an anomaly on an axial retaining bearing of the gearbox of a turbomachine according to one of the aforementioned embodiments, said method comprising the following successive steps: - Cutting of the inlet ferrule mechanically connected to said gas generator shaft following an axial displacement of said blower towards said gas generator; - Detection of an overspeed at the location of said gas generator shaft; - an engine shutdown. Presentation of the figures

[0036] The invention, as well as its various advantages, will be more easily understood in the light of the following description of illustrative and non-limiting embodiments thereof, and the accompanying drawings, among which:

[0037] [Fig-1] illustrates a schematic longitudinal cross-sectional view of a turbomachine aircraft according to the invention;

[0038] [Fig.2] is a partial longitudinal cross-sectional view of an aircraft turbomachine according to an embodiment of the invention;

[0039] [Fig.3] is another partial longitudinal cross-sectional view of an aircraft turbomachine according to an embodiment of the invention, and

[0040] [Fig.4] is another partial longitudinal sectional view of an aircraft turbomachine according to an embodiment of the invention.

[0041] Detailed description of an embodiment of the invention

[0042] Throughout the description, it is noted that the terms upstream and downstream are to be considered with respect to a main direction F, represented in [Fig.1], of normal gas flow (from upstream to downstream) for an aircraft turbomachine.

[0043] With reference first to [Fig. 1], a turbomachine 10 manufactured according to a prior art is shown. As is known, the turbomachine 10 comprises, from upstream to downstream along the principal direction F of normal gas flow, a fan 12 equipped with blades 13 and carried by a fan shaft 18, and a gas generator 11 including, in particular, a compressor 14 and driven by a gas generator shaft 16. The fan shaft 18 and the gas generator shaft 16 extend along an axis X of rotation of the turbomachine 10 and are rotationally linked by means of a reduction gear 20, or speed reduction device. Indeed, it is advantageous to rotate the fan at a lower rotational speed than that of the gas generator shaft.

[0044] The reducer 20 is for example of epicyclic type and is, by no means limiting, driven by a planetary pinion 24 carried by an input shaft 26 which is rotationally linked to the gas generator shaft 16. It also includes a planet carrier 49 attached to a housing 46 of the turbomachine, and a ring gear 48 which drives the blower shaft 18 of the blower 12.

[0045] The turbomachine further includes two axial retaining bearings 32, 24 allowing the blower 12 to be axially retained relative to the gas generator 11.

[0046] To deal with the possibility that one of the two axial retaining bearings 32, 24 might deteriorate or even break, for example the most downstream axial retaining bearing, the solution therefore proposes a mechanical decoupling device configured to decouple said reducer from said gas generator shaft following a critical event causing an axial displacement of said blower towards said gas generator.

[0047] An embodiment of the invention, taken by way of illustration but not limitation, of a turbomachine 10 with longitudinal axis X comprising a gas generator 11 and a blower 12 located upstream of the gas generator, said blower 12 being connected to a blower shaft 18 driven by a gas generator shaft 16 via a speed reducer 20.

[0048] Such a turbomachine is notably mounted on an aircraft.

[0049] The reducer 20 includes an inlet ferrule 21 mechanically connected to the gas generator shaft 16. This inlet ferrule is provided opposite a connecting arm 160 of the gas generator.

[0050] For example, the gas generator shaft may include a low-pressure turbine shaft line of the turbomachine, the inlet ferrule being able to be connected to a second ferrule itself connected to the low-pressure turbine shaft line.

[0051] As illustrated, the turbomachine 10 includes a mechanical decoupling device 9 configured to decouple the reducer 20 from the gas generator shaft 16 following a critical event causing axial displacement of the blower 12 towards the gas generator 11.

[0052] In the illustrated embodiment, such a critical event belongs to the list including wear or breakage of an axial retaining bearing 34 of the reducer 20.

[0053] As illustrated, the mechanical decoupling device 9 comprises at least one cutting head 90 configured to move between: - a normal operating situation of the turbomachine in which the cutting head is spaced from the inlet ferrule 21 by a non-zero axial clearance in a normal operating position of the turbomachine, and - a turbomachine operating situation in which a critical event occurs, the cutting head 90 coming into contact with the inlet ferrule 21 so as to mechanically decouple the reducer 20 from the gas generator shaft 16 by cutting the inlet ferrule 21.

[0054] The normal operating situation of the turbomachine may include a takeoff, cruise, or landing regime occurring normally.

[0055] In the normal operating situation, the axial play between the cutting head 90 and the inlet ferrule 21 is between 0.3mm and 1mm.

[0056] More specifically, in this embodiment, the cutting head 90 includes a downstream end 91 having a triangular shape with an apex axially towards the inlet ferrule 21.

[0057] This cutting head 90 is therefore configured, via the downstream end 91, to machine the inlet ferrule 21 in the event of slow axial advance of the blower shaft towards the gas generator shaft, and then to crack the inlet ferrule 21 via a portion of the cutting head 90 in continuity with the downstream end 91 upstream of this downstream end 91.

[0058] According to an embodiment not illustrated, the mechanical decoupling device 9 may comprise a plurality of cutting heads 90 circumferentially distributed uniformly around the X axis of the turbomachine and extending radially inwards.

[0059] This can help to balance the decoupling forces on the circumference of the mechanical decoupling device.

[0060] According to an alternative, the mechanical decoupling device may comprise a plurality of cutting heads circumferentially distributed non-uniformly around the X axis of the turbomachine.

[0061] The mechanical decoupling device 9 is here fixed to a stator 29 of the gearbox 20, which is mounted to move in translation relative to the gas generator. In this way, in the event of a critical event consisting of a failure of a bearing 34 axially retaining the gearbox 20, the blower advances axially towards the gas generator and the mechanical decoupling device 9 fixed to a stator 29 of the gearbox 20 comes into contact with the inlet ferrule 21 and damages or even cracks it.

[0062] As can be seen, the decoupling device 9 comprises, in addition to the cutting head 90, an anchoring leg 92 for fixing the decoupling device 9 to the stator 29 of the reducer 20, and a retaining leg 93 provided upstream of the anchoring leg 92 and configured to prevent the decoupling device 9 from tipping over when the decoupling device 9 is in contact with the input ferrule 21. The cutting head 90, the anchoring leg 92 and the retaining leg 93 are connected to each other by a base 94.

[0063] In the illustrated embodiment, the mechanical decoupling device 9 is made at least partially from a material among steels / titaniums.

[0064] This allows us to have a material with the necessary rigidity to withstand the advance of the flexible shaft line, i.e. the blower shaft and the blower.

[0065] More specifically, in this embodiment, the mechanical decoupling device 9 has a flexibility between 1.0E-9 and 3.0E-7 m / N.

[0066] Moreover, in this embodiment, the cutting head is made at least partially from a material among the carbides.

[0067] According to one variant, the cutting head 90 is made at least partially from a material among steels / titaniums.

[0068] This allows us to have a material with the necessary rigidity to cut the inlet ferrule.

[0069] The invention also relates to a method of managing an anomaly on an axial retaining bearing of the reducer 20 of a turbomachine 10.

[0070] This method, according to the invention, comprises the following successive steps: - cutting of the inlet ferrule 21 mechanically connected to the gas generator shaft 16 following an axial displacement of the blower 12 towards the gas generator 11; - detection of overspeed at the location of the gas generator shaft 16; - an engine stoppage.

[0071] According to one embodiment of the invention, this method may also include a step of verifying the integrity of the turbomachine, or a step of generating an alert signal for the pilot or technicians.

Claims

Demands

1. Turbomachine (10) of longitudinal axis (X) comprising a gas generator (11) and a blower (12) located upstream of the gas generator, said blower (12) being connected to a blower shaft (18) driven by a gas generator shaft (16) via a speed reducer (20), characterized in that said turbomachine (10) further comprises a mechanical decoupling device (9) configured to decouple said reducer (20) from said gas generator shaft (16) following a critical event causing axial displacement of said blower (12) towards said gas generator (11).

2. Turbomachine (10) according to claim 1, characterized in that said reducer (20) comprises an inlet ferrule (21) mechanically connected to said gas generator shaft (16), and in that said mechanical decoupling device (9) comprises at least one cutting head (90) configured to evolve between: - a normal operating situation of said turbomachine in which said cutting head is spaced from said inlet ferrule (21) by a non-zero axial clearance in a normal operating position of said turbomachine, and - an operating situation of said turbomachine in which a critical event occurs, said cutting head (90) coming into contact with said inlet ferrule (21) so as to mechanically decouple said reducer (20) from said gas generator shaft (16) by cutting said inlet ferrule (21).

3. Turbomachine (10) according to the preceding claim, characterized in that in said normal operating situation, said axial play is between 0.3mm and 1mm.

4. Turbomachine (10) according to any one of claims 2 or 3, characterized in that said mechanical decoupling device (9) is fixed to a stator (29) of said reducer (20), mounted movable in translation relative to said gas generator.

5. Turbomachine (10) according to any one of claims 2 to 4, characterized in that said cutting head (90) comprises an end downstream (91) having a triangular shape with a vertex oriented axially towards said inlet ferrule (21).

6. Turbomachine (10) according to any one of claims 2 to 5, characterized in that said gas generator shaft (16) comprises a low pressure turbine shaft line of said turbomachine (10), the inlet ferrule (21) being connected to a second ferrule itself connected to said low pressure turbine shaft line.

7. Turbomachine (10) according to any one of the preceding claims, characterized in that the mechanical decoupling device (9) is made at least partially from a material among steels / titaniums.

8. Turbomachine (10) according to any one of claims 2 to 7, characterized in that said cutting head (90) is made from a material among steels / titaniums.

9. Turbomachine (10) according to any one of claims 5 to 8, characterized in that said mechanical decoupling device (9) has a flexibility between 1.0E-9 and 3.0E-7 m / N.

10. Turbomachine (10) according to any one of claims 2 to 9, characterized in that said mechanical decoupling device (9) comprises a plurality of cutting heads (90) circumferentially distributed uniformly around the axis (X) of the turbomachine and extending radially inwards.

11. Turbomachine (10) according to any one of the preceding claims, characterized in that said critical event belongs to the list including wear or breakage of an axial retaining bearing (34) of the reducer (20).

12. Aircraft, characterized in that it comprises at least one turbomachine according to any one of claims 1 to 11.

13. A method for managing an anomaly on an axial retaining bearing of the gearbox (20) of a turbomachine according to any one of claims 2 to 10 or claim 11 taken in relation to any one of claims 2 to 10, said method comprising the following successive steps: cutting of said inlet ferrule (21) mechanically connected to said gas generator shaft (16) following an axial displacement of said blower (12) towards said gas generator (11); detection of an overspeed at the location of said gas generator shaft (16); an engine stoppage.