Turboprop capable of providing an emergency wind turbine function and method of implementation

Abstract

The invention relates to a turboprop (10) comprising: - a turbine (12) mechanically connected to an input (21) of a reducer (20); - a tail shaft (30) bearing a variable-pitch propeller (31); - a rotary electric machine (46); and - an electric oil pump (40) configured to supply a hydraulic circuit (33) for adjusting the pitch of the propeller (31), wherein the electric oil pump (40) is configured to supply a lubrication circuit (53) for lubricating the bearings (25) of the reducer (20).

Description

Description Title of the invention: TURBOPROPELLER CAPABLE OF PROVIDING A BACKUP WIND TURBINE FUNCTION AND METHOD OF IMPLEMENTATION Technical field

[0001] The invention relates to the field of turbomachines and more specifically that of turboprops.

[0002] The invention more specifically relates to a turboprop, an aircraft comprising such a turboprop and methods for controlling such a turboprop and aircraft. Prior art

[0003] In the event of an aircraft engine failure in flight, it is known to deploy a backup wind turbine, also known as a "Ram air turbine", to provide an emergency source of electrical power to the aircraft and thus ensure the continued operation of essential onboard systems such as flight controls and critical flight instruments.

[0004] Such a backup wind turbine includes a self-contained propeller, a dedicated electrical generator and a jacking system that allows the turbine to be deployed when needed.

[0005] In addition to the emergency wind turbine, and in the case of an aircraft powered by a turboprop, it is common practice to modify the pitch of the propeller blades of the failed turboprop in order to reduce its drag and the resulting thrust asymmetry. Such an operation is known as "feathering" the propeller and uses the propeller pitch control system to modify the blade pitch. Such a propeller pitch control system typically comprises a pitch control unit powered by a high-pressure hydraulic pump actuated via a mechanical connection to the turboprop turbine. An engine pump, also mechanically actuated by the turbine, is connected to the high-pressure pump, which it supplies with oil from a main oil tank.In the case of a so-called "double-acting" propeller, the pitch control unit selectively supplies the chambers of a double-acting cylinder for pivoting the turboprop propeller blades.

[0006] To enable the propeller to be feathered in the event of a turboprop failure and therefore in the event of loss of the mechanical source of actuation of the engine and high pressure pumps, the aircraft includes a dedicated electric pump, also called a "feathering pump" which supplies the pitch control unit from an auxiliary oil tank, the time for it to command the feathering of the the propeller.

[0007] The invention aims to optimize the mass of an aircraft equipped with at least one turboprop. Presentation of the invention

[0008] To this end, a turboprop engine is provided comprising a turbine provided with an output shaft mechanically connected to an input of a motion reducer and a propeller shaft carrying a variable-pitch propeller and which is mechanically connected to a main output of the motion reducer. A rotating electrical machine is mechanically coupled to the propeller shaft via the motion reducer, and an electric oil pump is configured to supply a hydraulic circuit for adjusting the pitch of the propeller from an auxiliary reservoir via a first pipe. According to the invention, the oil pump is also configured to supply via a second pipe a circuit for lubricating the bearings of the motion reducer. The second pipe comprises an electrically controlled valve.

[0009] Thus, it is possible to enable, using minor modifications to the hydraulic and electrical circuit of the turboprop, a conversion of a stopped turboprop into an emergency wind turbine in a sustainable operating mode permitted in particular by maintaining the lubrication of the bearings of the motion reducer. It is then possible to eliminate the emergency wind turbine of the prior art as well as its wiring, which lightens the aircraft and simplifies its construction.

[0010] According to other particular, non-exclusive and optional embodiments of the invention:

[0011] - the second pipe also includes a pressure reducing device; - the turboprop comprises an oil recovery circuit from the motion reducer, and the oil recovery circuit comprises a third oil supply line to the auxiliary tank; - the recovery circuit includes an electric recovery pump;

[0012] - the recovery circuit includes a recovery pump mechanically connected to the motion reducer;

[0013] - the recovery circuit includes a device for directing and / or blocking the circulation of the fluid; - the second pipe comprises a first non-return valve; - an oil supply duct for the lubrication circuit of the motion reducer bearings from a main reservoir comprises a second non-return valve; - the turbine output shaft includes a freewheel device; - the turboprop engine includes a high-pressure pump for supplying the pitch adjustment hydraulic circuit from the auxiliary tank and the high-pressure pump is configured to supply the pitch adjustment hydraulic circuit, including when the auxiliary tank is not pressurized.

[0014] The invention also relates to a method of controlling a turboprop as described above as an emergency wind turbine comprising the following steps:

[0015] - drive the electric oil pump so as to supply oil to the hydraulic circuit for adjusting the pitch of the propeller and the bearings of the turboprop,

[0016] - adjust the propeller pitch to generate the windmill effect to drive the propeller into rotation,

[0017] - the rotating electrical machine being driven in rotation by the propeller shaft due to the mechanical coupling between them, generating electricity by the rotating electrical machine.

[0018] The invention also relates to a control method, in which, when a turboprop of the plurality of turboprops implements the control method of the invention, the turboprop implementing the control method according to the invention is the turboprop among the plurality of turboprops which is the last to have stopped.

[0019] The following steps may also be planned:

[0020] - in the event that, during the implementation of the control method by the last turboprop to have stopped, it proves incapable of switching to emergency wind turbine mode, identification among the other turboprops of the plurality of turboprops that having the highest oil temperature,

[0021] - implementation by the identified turboprop of the control method according to the invention.

[0022] Finally, when the control method according to the claim is implemented by a turboprop engine which comprises a high-pressure pump for supplying the hydraulic pitch adjustment circuit from the auxiliary tank and the high-pressure pump is configured to supply the hydraulic pitch adjustment circuit, including when the auxiliary tank is not pressurized, the method comprises an additional step of stopping the drive of the electric oil pump once the rotating electrical machine generates electricity.

[0023] Advantageously, when the aircraft comprises a plurality of turboprop engines, the method comprises the following steps:

[0024] - the plurality of turboprops having been switched off, receiving a request for placement or automatic switching of at least one turboprop into an emergency wind turbine type operating mode,

[0025] - implementation by a turboprop of the plurality of turboprops of a control method according to the method previously described.

[0026] Preferably, when implementing such a control method by a turboprop of the plurality of turboprops, the turboprop implementing the control method is the turboprop among the plurality of turboprops which is the last to have stopped. And, when the last turboprop to have stopped proves incapable of switching to emergency wind turbine mode, the method comprises the following additional steps:

[0027] - identification among the other turboprops of the plurality of turboprops of the one having the highest oil temperature,

[0028] - implementation by the identified turboprop of the control method described previously.

[0029] Other characteristics and advantages of the invention will appear on reading the following description of a particular non-limiting embodiment of the invention. Brief description of the figures

[0030] The invention will be better understood by reading the following description, given as a non-limiting example, and made with reference to the figures which represent:

[0031] [Fig.l] is a schematic view of a turboprop according to a first embodiment of the invention;

[0032] [Fig.2] is a schematic view of a turboprop according to a second embodiment of the invention.

[0033] In these figures, like reference numerals from one figure to another designate like or similar elements. Furthermore, for reasons of clarity, the drawings are not to scale, unless otherwise indicated. Description of embodiments

[0034] With reference to [Fig.l], an aircraft not shown comprises at least one turboprop 10 of the gas generator 11 and free turbine 12 type, the turbine 12 of which is provided with an output shaft 13 mechanically connected to an input 21 of a motion reduction box 20 by a freewheel device 14. The box 20 comprises a main output 22 connected to a propeller shaft 30 which carries a variable pitch propeller 31 of the “double-acting” type known per se. The pitch of the propeller 31 is hydraulically controlled by a pitch control unit 32 connected to the propeller 31. The unit 32 is part of a circuit of a hydraulic circuit 33 for adjusting the pitch of the propeller 31 and is connected to an electric oil pump 40 via a first pipe 41. The pump 40 is also known as a “feathering pump”.The unit 32 is also hydraulically connected to a high-pressure mechanical pump 42 connected by a shaft 43 to a first auxiliary outlet 23 of the housing 20. A main supply line 44 extends between the pump 42 and the unit 32. The. first pipe 41 connects to pipe 44. Pumps 40 and 42 are both connected to an auxiliary oil tank 45.

[0035] A rotating electrical machine 46 is connected to a second auxiliary output 24 of the housing 20 and is thus mechanically coupled to the propeller shaft 30. The machine 46 operates as an electrical generator and is connected to an electrical network (not shown) of the aircraft which notably includes electrical storage batteries.

[0036] In a manner known per se, the turboprop 10 comprises a motor pump 50 driven by the gas generator 11 and which draws oil from a main tank 51 to supply a first lubrication circuit 52 for the bearings 15 of the gas generator 11 and the turbine 12 and a second lubrication circuit 53 for the bearings 25 of the housing 20. This supply is done via a main pipe 55 which supplies a first tapping 56 connected to the circuit 52 and a second tapping 57 connected to the circuit 53. The turboprop 10 also comprises a main recovery pump 58 driven by the gas generator 11 and which is connected by an oil recovery pipe 59 to the housing 20 to recover the bottom oil collected by runoff and transfer this oil to the main tank 51 via a fourth pipe 59.1 after passing through a filtering and heat exchange assembly (not shown). Finally, a pressurization pipe 60 extends between the pump 50 and the tank 45.

[0037] Specifically to the invention, the turboprop 10 comprises a second pipe 48 which is connected to the pipe 44 and connects the pipe 44 to the pipe 55 upstream of the connection 57, thus putting the pump 40 and the lubrication circuit 53 into fluid communication. A first non-return valve 49 located on the second pipe 48 prevents the circulation of fluid from the pipe 55 to the pipe 44. The valve 49 comprises an electrically controlled valve 49.1 and a pressure reducer. 49.2 ensuring that a suitable supply pressure is applied at the inlet of the lubrication circuit 53. A second valve 61 located on the pipe 55 downstream of the tapping 56 and upstream of the tapping point of the pipe 48 prevents the circulation of fluid from the pipe 44 to the lubrication circuit 52.

[0038] An auxiliary recovery pump 70 is connected to the housing 20 by a third tapping 71 taken from the pipe 59 upstream of the pump 58. The pump 70 is an electric pump, one outlet 72 of which is connected by a third pipe 73 to the reservoir 45. An electrically controlled valve 74 makes it possible to selectively fluidically connect the outlet 72 of the pump 70 and the reservoir 45. The pump 58, the pipe 59, the pump 70, the tapping 71 and the pipe 73 constitute a recovery circuit 76 for the bottom oil of the housing 20.

[0039] All electrical equipment (pumps and electro-controlled valves) are connected to a control and power supply unit (not shown).

[0040] The operation of the turboprop 10 will now be described in a first nominal operating mode and in a second emergency operating mode, when the gas generator 11 and / or the free turbine 12 are stopped.

[0041] In nominal operating mode, the gas generator 11 drives the free turbine 12 which sets the propeller 31 in rotation via the housing 20. The gas generator 11 also drives:

[0042] - the motor pump 50 which pressurizes the auxiliary tank 45 via the pipe 60 and supplies the lubrication circuits 52 and 53; - the main recovery pump 58 which returns the bottom oil from the housing 20 to the main tank.

[0043] The housing 20 also transmits the movement of the turbine 12 to the following components:

[0044] - the electrical machine 46 which then generates electrical current for the aircraft's electrical network; - the high pressure pump 42 which supplies the propeller pitch control unit 32.

[0045] The electric pumps 40 and 70 are not energized in nominal operating mode. The valve 61 allows the circulation of oil to the circuit 53 and the valve 49 prevents the oil sent by the pump 50 to the lubrication circuit 53 from coming to the inlet of the propeller pitch control unit 32. The valve 74 is controlled so as to prevent oil from flowing back to the pump 70 when the reservoir 45 is pressurized.

[0046] The transition to degraded mode is made after the avionics has detected a stoppage of the gas generator 11 and / or the free turbine 12 and the feathering of the propeller 31 has been carried out according to known methods using the pump 40. The transition to degraded mode comprises several steps. According to a first step, the electric oil pump 40 is controlled so that it supplies the hydraulic adjustment circuit 33 with oil via the pipe 41. The oil supplied by the oil pump 40 also circulates in the second pipe 48, passes through the valve 49 which is in the open position and supplies the lubrication circuit 53 of the bearings 25 of the housing 20. The valve 61 prevents part of the oil flow from the pump 40 from unnecessarily supplying the bearings of the gas generator which is no longer rotating. In a second step, an adjustment of the pitch of the propeller 31 is controlled in order to generate a windmill effect to drive the propeller 31 in rotation.The apparent wind caused by the movement of the aircraft drives the propeller 31 in rotation which transmits this movement to the auxiliary outputs 23 and 24 of the housing 20 via the shaft 30. The freewheel device 14 allows decoupling of the free turbine 12 when the propeller 31 is driving the auxiliary outputs 23 and 24 of the housing 20. The auxiliary output 23 allows the actuation of the. high pressure pump 42 which then supplies the unit 32 as well as the circuit 53 via the second pipe 48. The pump 40 is then kept under tension in order to supply the pitch control unit 32 with pressurized oil. During these steps, the auxiliary oil recovery pump 70 is kept in operation and the valve 74 is controlled to authorize the admission of oil from the pump 70 to the tank 45. The rotating electrical machine 46 being driven in rotation by the outlet 24 of the housing 20, it generates electricity and can thus provide the power for the minimum functionalities of the aircraft and recharge the batteries to power the electric oil pump 40 and the recovery pump 70.

[0047] This then provides operation of the propeller 31 as an emergency wind turbine which allows maintenance of the lubrication of the bearings of the housing 20, thus ensuring long-term non-destructive operation of the propeller 31 as an emergency wind turbine. The auxiliary recovery pump 70 allows the establishment of a supply loop of the auxiliary tank 45 from the housing 20 ensuring a continuous supply of the propeller pitch adjustment circuit 33 and the lubrication circuit 53. The valve 61 and the freewheel 14 make it possible to optimize the mechanical energy supplied by the propeller 31 by isolating the unnecessary mechanical and hydraulic “loads” from operation in degraded mode.

[0048] Elements identical or analogous to those previously described will bear a numerical reference identical to this in the following description of a second embodiment of the invention.

[0049] According to a second embodiment shown in [Fig.2], the recovery pump 80 is, here, a mechanically driven pump connected by a shaft 81 to a third auxiliary output 27 of the housing 20.

[0050] The main recovery pump 58 of the first embodiment driven by the gas generator 11 and the electrically driven recovery pump 70 are removed and replaced by a single mechanical recovery pump 80 connected by a shaft 81 to a third auxiliary outlet 27 of the housing 20. An oil recovery conduit 82 connects the pump 80 to the housing 20 to recover the bottom oil collected by runoff and transfer this oil to a three-way valve 83. The three-way valve 83 selectively directs the flow of oil to the auxiliary tank 45 or the main tank 51 via the conduit 59.1 after passing through a filtering and heat exchange assembly 84.

[0051] The operation of the turboprop 10 according to this second embodiment will now be described in a first nominal operating mode and in a second emergency operating mode, when the gas generator 11 and / or the free turbine 12 are stopped.

[0052] In nominal operating mode, the gas generator 11 drives the free turbine 12 which sets the propeller 31 in rotation via the housing 20. The gas generator 11 also drives the motor pump 50 which pressurizes the auxiliary tank 45 via the pipe 60 and supplies the lubrication circuits 52 and 53.

[0053] The housing 20 also transmits the movement of the turbine 12 to the following components:

[0054] - the electrical machine 46 which then generates electrical current for the aircraft's electrical network; - the high pressure pump 42 which supplies the propeller pitch control unit 32; - the recovery pump 80 which returns the bottom oil from the housing 20 to the main tank 51, the three-way valve 83 being controlled to direct the flow of oil from the pump 80 to the main tank 51.

[0055] The electric pump 40 is not energized in nominal operating mode. The valve 61 allows the circulation of oil to the circuit 53 and the valve 49 prevents the oil sent by the pump 50 to the lubrication circuit 53 from coming to the inlet of the propeller pitch control unit 32.

[0056] The transition to degraded mode is made after the avionics has detected a stoppage of the gas generator 11 and / or the free turbine 12 and the feathering of the propeller 31 has been carried out according to known methods using the pump 40. The transition to degraded mode comprises several steps. According to a first step, the electric oil pump 40 is controlled so that it supplies the hydraulic adjustment circuit 33 with oil via the line 4L. The oil supplied by the oil pump 40 also circulates in the second line 48, passes through the valve 49 which is in the on position and supplies the lubrication circuit 53 of the bearings 25 of the housing 20. The valve 61 prevents part of the oil flow from the pump 40 from unnecessarily supplying the bearings of the gas generator which is no longer rotating. In a second step, an adjustment of the pitch of the propeller 31 is controlled in order to generate a windmill effect to drive the propeller 31 in rotation.The apparent wind caused by the movement of the aircraft drives the propeller 31 in rotation which transmits this movement to the auxiliary outputs 23 and 24 of the housing 20 via the shaft 30. The freewheel device 14 allows decoupling of the free turbine 12 when the propeller 31 is driving the auxiliary outputs 23, 24 and 27 of the housing 20. The auxiliary output 23 allows the actuation of the high pressure pump 42 which then supplies the unit 32 as well as the circuit 53 via the second pipe 48. The pump 40 can then be kept under tension in order to supply the pitch control unit 32 with pressurized oil. The oil recovery pump 80 is actuated via the housing 20 and the three-way valve 83 is controlled to direct the flow of oil from the pump 80 to the reservoir 45. The rotating electrical machine 46 being driven in rotation by the output 24 of the housing 20, it generates. electricity and can thus provide power for the minimum functionality of the aircraft and recharge the batteries to power the electric pump 40.

[0057] Such a turboprop 10 makes it possible, when it equips an aircraft, to provide an emergency wind turbine function. When an aircraft is equipped with a plurality of turboprop engines 10 according to the invention, it can be configured to implement a control method comprising, while the aircraft is in flight, the following steps:

[0058] -all of the turboprops 10 of the plurality of turboprops having been stopped, reception of a request for placement or automatic passage (for example on instruction from a control unit of the aircraft not shown) of at least one turbomachine into an operating mode of the emergency wind turbine type,

[0059] - implementation, by one of the turboprops 10 of the plurality of turboprops, of a method for controlling the latter as an emergency wind turbine, as mentioned above, this turboprop 10 preferably being the turboprop 10 among the plurality of turboprops which is the last to have stopped.

[0060] It will be noted that, in the case where, during the implementation of the control method by the last turboprop to have stopped, the latter proves incapable of switching to emergency wind turbine mode, it can be identified among the other turboprops of the plurality of turboprops 10 that having the highest oil temperature. Once said turboprop 10 having the highest oil temperature has been identified, the latter can be configured to implement the control method according to the invention to be placed in emergency wind turbine mode.

[0061] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0062] Especially,

[0063] - although here the recovery circuit comprises a piloted valve, the invention also applies to other types of device for blocking the circulation of a fluid, such as for example a valve or a non-piloted valve; - although here the recovery circuit comprises a three-way valve, the invention also applies to other types of device for directing the circulation of a fluid such as for example a piloted valve assembly; - although here the valve 74 is an electrically controlled valve, the invention also applies to a simple valve, without control; - although here the pump 40 is kept under voltage during the transition to degraded mode, the invention also applies to a transition to degraded mode in which the electrical power supply to the pump 40 is cut off, it is then necessary to provide that the high pressure pump 42 has the capacity to bring the unpressurized oil from the auxiliary tank at a pressure sufficient to supply the propeller pitch control unit 32. This can be achieved in particular using a self-priming pump.

Claims

Claims

1. Turboprop (10) comprising: - a turbine (12) provided with an output shaft (13) mechanically connected to an input (21) of a motion reducer (20); - a propeller shaft (30) carrying a variable pitch propeller (31) and which is mechanically connected to a main output (22) of the motion reducer (20), - a rotating electrical machine (46) mechanically coupled to the propeller shaft (30) via the motion reducer (20), and - an electric oil pump (40) configured to supply a hydraulic circuit (33) for adjusting the pitch of the propeller (31) from an auxiliary tank (45) via a first pipe (41), the turboprop (10) being characterized in that the electric oil pump (40) is also configured to supply via a second pipe (48) a lubrication circuit (53) of the bearings (25) of the motion reducer (20), the second pipe (48) comprising an electrically controlled valve (49.1).

2. A turboprop engine (10) according to claim 1, wherein the second conduit (48) also comprises a pressure reducing device (49.2).

3. Turboprop (10) according to claim 1 or 2, comprising a recovery circuit (76) for oil from the motion reducer (20), the oil recovery circuit (76) comprising a third pipe (59) for supplying oil to the auxiliary tank (45).

4. A turboprop engine (10) according to claim 3, wherein the recovery circuit (76) comprises an electric recovery pump (70).

5. Turboprop (10) according to claim 3, in which the recovery circuit (76) comprises a recovery pump (80) mechanically connected to the motion reducer (20).

6. Turboprop (10) according to one of claims 3 to 5, in which the recovery circuit (76) comprises a device for directing and / or blocking the circulation of the fluid.

7. Turboprop according to one of claims 1 to 6, in which the second pipe (48) comprises a first non-return valve (49).

8. Turboprop (10) according to one of claims 1 or 7, in which a supply duct (55) for oil in the lubrication circuit (53) of the bearings (25) of the movement reducer (20) from a reservoir main (51) comprises a second non-return valve (61).

9. Turboprop (10) according to one of claims 1 to 8, in which the output shaft (13) of the turbine (12) comprises a freewheel device (14).

10. Turboprop (10) according to one of claims 1 to 9, comprising a high pressure pump (42) for supplying the hydraulic pitch adjustment circuit (33) from the auxiliary tank (45), the high pressure pump being configured to supply the hydraulic pitch adjustment circuit (33), including when the auxiliary tank (45) is not pressurized.

11. A method of controlling a turboprop engine (10) according to any one of claims 1 to 10 as a backup wind turbine, the method comprising the following steps: - drive the electric oil pump (40) so as to supply oil to the hydraulic circuit (33) for adjusting a pitch of the propeller (31) and a lubrication circuit (53) for the bearings (25) of the movement reducer (20), - adjust the pitch of the propeller (31) in order to generate the windmill effect to drive the propeller (31) in rotation, - the rotating electrical machine (46) being driven in rotation by the propeller shaft (30) due to the mechanical coupling between them, generating electricity by the rotating electrical machine (46).

12. A method of controlling an aircraft comprising a plurality of turboprop engines (10) according to any one of claims 1 to 10, comprising, while the aircraft is in flight, the following steps: - the plurality of turboprops (10) having been switched off, receiving a request for placement or automatic switching of at least one turboprop (10) into an operating mode of the emergency wind turbine type, - implementation by a turboprop (10) of the plurality of turboprops (10) of a control method according to claim 11.

13. The control method of claim 12, wherein, when a turboprop engine (10) of the plurality of turboprop engines implements a control method according to claim 11, the turboprop engine (10) implementing the control method according to claim 11 is the turboprop engine (10) among the plurality of turboprop engines (10) that is the last to have stopped.

14. A control method according to claim 13, wherein it is furthermore provided: - in the case where, during the implementation of the control method by the last turboprop (10) to have stopped, the latter proves incapable of switching to emergency wind turbine mode, identification among the other turboprops (10) of the plurality of turboprops (10) that having the highest oil temperature, - implementation by the identified turboprop (10) of the control method according to claim 11.

15. A control method according to claim 12, wherein, when the control method according to claim 11 is implemented by a turboprop engine (10) according to claim 10, the method comprises a further step of stopping the drive of the electric oil pump (40) once the rotating electrical machine (46) generates electricity.

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