Patent Application
20240392695
The invention relates to the field of the oil tanks for the aircraft turbine engines. More specifically, the invention relates to the field of the oil tanks for the phases of flight during which the gravitational force is zero (0 g condition) or negative (negative g condition).
The prior art is illustrated by the documents US-A1-2020116048, FR-A1-3105296 and US-A1-2015060206.
A turbine engine for an aircraft comprises, from upstream to downstream, at least one first rotor, also referred to as a thruster rotor, such as a propeller when the turbine engine is a turboprop engine, or an unducted fan when the turbine engine is of the “open rotor” type, or a ducted fan when the turbine engine is a turbojet engine, a compressor, a combustion chamber and a turbine. The rotor of the compressor is connected to the rotor of the turbine and the first rotor by a drive shaft. An air flow is compressed within the compressor, then the compressed air is mixed with a fuel and burnt within the combustion chamber. The gases formed by the combustion pass through the turbine, which allows to drive the rotor of the compressor and the rotor of the thruster.
The propeller or the fan of the thruster rotor and the rotor of the compressor are equipped with vanes that allow them to exert an action on the air flow. In order to adapt the turbine engine to the flight conditions, it is known to equip the thruster rotor with variable pitch angle vanes or the rotor of the compressor with variable pitch angle vanes. To this end, the turbine engine comprises a control system for controlling the variable pitch angle of the vanes which comprises a control unit connected to a hydraulic actuator to rotate the vanes relative to a longitudinal axis of the vanes according to the orientation of the air flow.
In order to supply oil to the control system and in particular to the hydraulic actuator, as well as to other elements of the turbine engine such as bearings and reducers, the turbine engine typically comprises a main oil supply system. This supply system comprises, for example, a main tank connected to a first supply circuit for lubricating the bearings and to a second supply circuit for supplying oil to the hydraulic actuator. A supply pump is mounted on the second supply circuit, allowing oil to be sucked from the main tank and circulated to the hydraulic actuator. The main tank typically comprises an enclosure with a lower and upper wall joined by transverse walls. The lower wall comprises an aperture connected to the pump for the suction of the oil.
Certain phases of aircraft flight disrupt the oil supply to the hydraulic actuator. In fact, the aircraft can experience phases of flight during which the gravitational force is zero or negative. In the context of the invention, these phases of flight are referred to as the “0 g condition” when the gravitational force is zero, or the “negative g condition” when the gravitational force is reversed. During such phases of flight, the oil contained in the main tank is pressed against the upper wall of the tank opposite the aperture in negative g conditions, or the oil and air form a suspension charged with air bubbles in 0 g conditions. As a result, the pump no longer sucks oil from the tank but air or oil with a high air bubble content, which impairs the oil supply to the control system and can even cause the supply pump to stop. In all cases, the hydraulic actuator of the control system is no longer correctly supplied with oil.
Such a deterioration in the oil supply to the control system, and in particular to the hydraulic actuator, can render the pitch setting of the vanes of the thruster rotor uncontrollable, in particular the blades of the propeller or of the unducted fan, which can lead to the vanes being feathered by a safety system. This significantly reduces the thrust of the turbine engine, leading to a loss of control, which is unacceptable.
Consequently, there is a need to provide an oil tank to supply oil to the control system for controlling the variable pitch angle vanes during the phases of flight when the gravitational force is zero or negative.
To this end, the invention proposes an auxiliary oil tank for supplying a control system for controlling the pitch of vanes of an aircraft turbine engine, comprising an enclosure comprising:
The enclosure is characterised in that it further comprises:
The tank according to the invention therefore comprises a baffle which allows to separate the first internal volume from the second internal volume. When the aircraft experiences a phase of flight during which the gravitational force is zero or negative, the air entering through the first outlet port circulates through the enclosure from the first internal volume towards the second internal volume. According to the invention, the circulation of air between the two volumes is slowed by the baffle, which allows the oil contained in the second internal volume to remain in communication with the second outlet port to supply the second circuit. This prevents the air from reaching the second outlet port. Thanks to the invention, the auxiliary tank is able to supply the control system during such a flight phase. The vanes are therefore not feathered and the aircraft turbine engine maintains a maximum thrust during this phase of flight.
The invention may comprise one or more of the following characteristics, taken alone or in combination with each other:
The invention also relates to a turbine engine for an aircraft comprising:
The turbine engine may comprise one or more of the following characteristics, taken singly or in combination:
Further characteristics and advantages will be apparent from the following description of a non-limiting embodiment of the invention with reference to the appended drawings in which:
A turbine engine 1, 1′,1″ for an aircraft is shown, for example, in
The rotor of the high-pressure turbine 6 is connected to the rotor of the high-pressure compressor 4 by a high-pressure shaft 9. The rotor of the low-pressure turbine 7 is connected to the rotor of the low-pressure compressor 3 by a low-pressure shaft 10.
The low-pressure 10 and high-pressure 9 shafts are supported by bearings 12a. The bearings 12a are contained in a lubrication enclosure 12 for their lubrication. For example, an upstream bearing 120a is arranged radially between an upstream end of the low-pressure shaft 10 and an upstream bearing support 120b and a downstream bearing 120a′ is arranged downstream of the upstream bearing 120a and radially between the low-pressure shaft 10 and a downstream bearing support 120b′. The lubrication enclosure 12 is annular. The upstream and downstream bearings 120a, 120a′ are arranged in the lubrication enclosure 12.
The first rotor 2 is driven in rotation by a rotor shaft 100. The rotor shaft 100 is connected to the low-pressure shaft 10. The low-pressure shaft 10 drives in rotation the rotor shaft 100. Advantageously, the low-pressure shaft 10 is connected to the rotor shaft 100 by a speed reducer 11. This allows the first rotor 2 to be driven at a lower speed than the speed of rotation of the low-pressure shaft 10. The speed reducer 11 is for example arranged in the lubrication enclosure 12 between the upstream bearing 120a and the downstream bearing 120a′.
The main air flow F passes through the turbine engine 1, 1′, 1″ and divides into a primary air flow F1 which passes through the engine M in a primary duct and a secondary air flow F2 which passes through the first rotor 2 in a secondary duct surrounding the primary duct.
The turbine engine 1, 1′, 1″ comprises vanes 2a that allow to exert an action on the main air flow F or primary air flow F1 or the secondary air flow F2. For example, the rotors of the low-pressure 3 and high-pressure 4 compressors comprise vanes 2a which allow to compress the primary air flow F1 upstream of the combustion chamber 5.
In general, the vanes 2a can be stationary in rotation about the longitudinal axis X, or can be movable in rotation about the longitudinal axis X or an axis parallel to the longitudinal axis X.
In a first embodiment shown in
In a second embodiment shown in
In a third embodiment shown in
The vanes 2a extend radially with respect to the longitudinal axis X. They typically comprise a blade and an element for attachment to the disc. The attachment element is, for example, a root or a platform. According to the invention, the vanes 2a have a variable pitch angle. By variable pitch angle, it is understood that the vanes 2a are movable in rotation about a transverse axis Z substantially perpendicular or perpendicular to the longitudinal axis X.
In order to control the pitch angle of the vanes 2a, the turbine engine 1, 1, 1″ according to the invention comprises a system 13 for controlling the variable pitch angle vanes 2a. The control system 13 comprises a control unit 13a and at least one hydraulic actuator 13b supplied with oil. The control unit 13a is, for example, stationary in rotation about the longitudinal axis X. The control unit 13a is connected, for example, to a stator of the turbine engine 1, 1, 1″. The control unit 13a is known in the field of the invention by the acronym PCU for “Pitch Control Unit”. The hydraulic actuator 13b is, for example, a hydraulic cylinder comprising a rod that is movable in translation and is connected to the vane 2a, possibly via a mechanism for transforming the movement. The translational movement of the rod allows the vane 2a to rotate around its axis. The translational movement of the movable rod is controlled by the control unit 13a, which supplies oil to the hydraulic actuator 13b. The hydraulic actuator 13b is movable in rotation about the longitudinal axis X or about an axis parallel to the longitudinal axis X. The hydraulic actuator 13b is, for example, secured in rotation to the vanes 2a. The hydraulic actuator 13b, for example, is arranged upstream of the control unit 13a.
Advantageously, the control system 13 comprises a device for transferring oil 13c from the control unit 13a towards the hydraulic actuator 13b. The oil transfer device 13c transfers oil from the control unit 13a which is stationary towards the hydraulic actuator 13b which is movable in rotation. The oil transfer device 13c is known by the acronym OTB for “Oil Transfer Bearing”. The oil transfer device 13c is located in the lubrication enclosure 12, for example.
The turbine engine 1, 1′, 1″ also comprises an electrical control unit 24. The electrical control unit 24 is used to drive the control unit 13a. The electrical control unit 24 is, for example, a FADEC (Full Authority Digital Engine Control).
In addition, the turbine engine 1, 1′, 1″ comprises an oil supply system comprising a main supply system 14 and an auxiliary supply device 14′, shown in
The main supply system 14 lubricates the bearings 12a within the lubrication enclosure 12 and the reducer 11 and supplies oil to the control system 13 during a first operating phase of the turbine engine 1, 1′, 1″. The auxiliary supply device 14′ ensures the lubrication of the control system 13 during a second operating phase of the turbine engine 1, ′1, 1″ during which the gravitational force is zero (0 g condition) or reversed (negative g condition).
The main oil supply system 14 comprises a first oil supply circuit 14a for supplying the lubrication enclosure 12 and a second oil supply circuit 14b for supplying the control system 13. The main supply system 14 advantageously comprises a variable diaphragm metering valve 19. The metering valve 19 allows to supply oil to the speed reducer 11. In a first embodiment, this metering valve 19 may have the function of a valve for distributing the oil distributed between the lubrication enclosure 12 and the speed reducer 11.
The main supply system 14 advantageously comprises an oil recovery circuit 14a′ from the lubrication enclosure 12 and an oil recovery circuit 14b′ from the control system 13.
The main supply system 14 also comprises a main oil tank 15 connected to the first supply circuit 14a and the second supply circuit 14b.
The oil sent to the bearings 12a, for example the upstream bearing 120a and the downstream bearing 120a′, to the reducer 11 and the oil leaks from the transfer device 13c, fall back to the bottom of the lubrication enclosure 12. To optimise oil consumption, this oil is recovered and directed, for example, into the oil recovery circuit 14a′ of the lubrication enclosure 12.
The first supply circuit 14a comprises a first supply pump 16a allowing to suck oil from the main tank and its circulation through the first supply circuit 14a to supply oil to the lubrication enclosure 12. Advantageously, the first supply circuit 14a comprises a main exchanger 17a, for example air/oil or oil/fuel, and optionally a second exchanger 17b, for example oil/fuel, which are arranged between the first pump 16a and the lubrication enclosure 12.
The circuit 14a′ for recovering oil from the lubrication enclosure 12 comprises a second recovery pump 16b connected to the lubrication enclosure 12 and to the main tank 15. The pump 16b allows to recover the oil from the lubrication enclosure 12 and returns it to the main tank 15 via the recovery circuit 14a′.
In addition, the main supply system 14 comprises a supply pump 18 dedicated to supplying oil to the control system 13. The supply pump 18, for example, is mounted on the second supply circuit 14b. The supply pump 18 is a positive displacement pump, for example. The positive displacement pump may have a stationary or variable displacement. The supply pump 18 comprises an inlet 18a and an outlet 18b connected to the control system 13.
The second supply circuit 14b may comprise a filter 26 arranged between the supply pump 18 and the control system 13.
During the first operating phase of the turbine engine 1, 1′, 1″, the first pump 16a sucks oil from the main tank 15 and allows the oil to circulate through the first supply circuit 14a to the lubrication enclosure 12. The supply pump 18 also sucks oil from the main tank 15, for example upstream or downstream of the first pump 16a, and conveys the oil through the second supply circuit 14b to the control system 13.
During the second phase of operation, typically a flight in negative (or inverted) gravity, the oil is pressed into the upper portion of the main tank 15 while the lower portion connected to the first pump 16a is occupied by air. In zero gravity, an air-oil mixture is suspended in the tank 15 and in reverse gravity, air occupies the lower portion of the main tank 15 connected to the first pump 16a. The supply pump 18 is indirectly connected to the lower portion of the main tank 15, and therefore runs the risk of sucking air from the main tank 15, or oil with a high air bubble content. This is not acceptable because the control system 13 must be supplied with oil that is relatively free of air bubbles, so as not to compromise the operation of the control unit 13a and therefore the hydraulic actuator 13b that controls the pitch of the vanes 2a. The presence of air can also cause the supply pump 18 to stop. Consequently, in order to ensure a suitable oil supply for the control system 13 during the second phase of operation of the turbine engine 1, 1′, 1″, the invention proposes an auxiliary supply device 14′. The auxiliary supply device 14′ is mounted on the second supply circuit 14b.
The auxiliary supply device 14′ comprises an auxiliary oil tank 20, optionally an auxiliary pump 22 and a valve 21. The auxiliary pump 22 comprises an inlet 22a and an outlet 22b. The valve 21 is, for example, a 3/2 hydraulic directional control valve, i.e. it has three apertures and two positions.
In a first embodiment shown in
In this embodiment, the valve 21 is a spring-return hydraulically-operated directional control valve. The valve 21 has a body 21a with an inlet connected to the outlet 22b of the auxiliary pump 22 and a first outlet connected to the auxiliary tank 20 and a second outlet connected to the second supply circuit 14b, between the supply pump 18 and the control system 13. The valve 21 further comprises a movable member in the body 21a configured to move between a first position in which the inlet of valve 21 is in fluid communication with the first outlet of the valve 21 and a second position in which the inlet of the valve 21 is in fluid communication with the second outlet of the valve 21. The valve 21 comprises, for example, a return spring for returning the movable member from the second position towards the first position.
In the first position, as shown in
In the second position (not shown), the auxiliary pump 20 sucks oil from the auxiliary tank 20 and the oil is conveyed to the control system 13 via the second supply circuit 14b, for example. Thus, when the turbine engine 1, 1′, 1″ is in the first operating phase, in particular when the aircraft is in a “normal” flight phase, the valve 21 is in the first position. When the turbine engine 1, 1′, 1″ is in the second operating phase, in particular when the aircraft is in a flight phase in which the gravitational force is zero (called “0 g”) or negative (called “negative g”), the valve 21 is in the second position. This allows to ensure that the control system 13 is supplied with oil from the auxiliary tank 20 and avoids any interruption in the oil supply to the control system 13. The auxiliary pump 22 is therefore active both when the movable member of the valve 21 is in the first position and in the second position. This allows to eliminate the need for a priming time for the auxiliary pump 22 and ensures a rapid oil supply to the control system 13 during the second operating phase of the turbine engine 1, 1′, 1″.
The valve 21 comprises a hydraulic actuation chamber connected to the inlet 18a of the supply pump 18. When the turbine engine 1, 1′, 1″ is in the second operating phase (negative or zero gravity), the pressure in the first supply circuit 14a drops as the first pump 16a sucks in air or an air-oil mixture from the main tank 15. The pressure at the inlet 18a of the supply pump 18 connected to the first supply circuit 14a then falls below a threshold pressure, which causes the movable member of the valve 21 to move into the second position under the action of the spring of the valve. This configuration allows to simplify the control of the valve 21. This does not require a special sensor, since it is activated by the sharp drop in pressure at the inlet 18a of the supply pump 18.
Alternatively, the valve 21 is directly sensitive to the gravitational force.
Furthermore, according to this first embodiment, advantageously, the auxiliary supply device 14′ also comprises a pressure limiter 25a arranged at the outlet of the auxiliary pump 22, between the auxiliary pump 22 and the valve 21. The pressure limiter 25a is, for example, a non-return valve.
According to this first embodiment, the metering valve 19 is mounted on the first supply circuit 14a. The metering valve 19 is mounted between the first pump 16a and the lubrication enclosure 12. Preferably, the metering valve 19 is mounted between the main exchanger 17a, which in this mode is an oil/fuel exchanger, and the second exchanger 17b. In this first embodiment, the metering valve 19 acts as a valve for distributing the oil distributed between the lubrication enclosure 12 and the speed reducer 11. This is a valve with two outlets. The first outlet of the metering valve 19 is connected to the lubrication enclosure 12 and the second outlet of the metering valve 19 is connected to the reducer 11. The metering valve 19, for example, is controlled by the electrical control unit 24.
In addition, according to this example, a third exchanger 17c, for example air/oil, connects the second outlet of the metering valve 19 and the reducer 11.
In a preferred embodiment of the invention, the supply pump 18 comprises a non-return valve 25b to ensure that all the oil delivered by the auxiliary pump 22 supplies the control system 13.
In a second embodiment shown in
It is thus understood that in the first position, the supply pump 18 sucks oil from the main tank 15 and in the second position, the supply pump 18 sucks oil from the auxiliary tank 20. The valve 21 thus allows to control the flow of oil in the second circuit 14b. When the turbine engine 1, 1, 1″ is in a first operating phase, in particular when the aircraft is in a “normal” flight phase, the valve 21 is in the first position and the main pump 18 sucks oil from the main tank 15 to supply the control system 13. When the turbine engine 1, 1, 1″ is in a second operating phase, in particular when the aircraft is in a flight phase in which the gravitational force is zero (referred as the 0 g condition) or negative (referred as the negative g condition), the valve 21 is in the second position and the main pump 18 sucks oil from the auxiliary tank 20 to supply the control system 13 with oil.
In a first example of embodiment, the valve 21 is electrically controlled. According to this example, the turbine engine 1, 1, 1″ comprises a sensor configured to deliver a signal to the electrical control unit 24. The sensor is configured to detect the second operating phase of the turbine engine 1, 1, 1″. The sensor is an accelerometer, for example.
According to a second example of embodiment, the movable member of the valve 21 is directly sensitive to the gravitational force exerted on the turbine engine 1, 1, 1″. When the gravitational force is greater than a given threshold, i.e. in the first operating state, the movable member is in the first position. In the second operating state, the movable member detects the second operating state and moves to the second position.
The auxiliary pump 22 in this second embodiment is optional. The auxiliary pump 22 is, for example, a centrifugal pump connected to the outlet of the valve 21. The auxiliary pump 22 is therefore arranged between the valve 21 and the supply pump 18. The pump inlet 18a is therefore connected to the valve outlet 21 via the auxiliary pump 22. Optionally, a second air/oil exchanger 23 is arranged between the valve 21 and the supply pump 18. More specifically, the second air/oil exchanger 23 is arranged between the centrifugal pump 22 and the supply pump 18. The centrifugal pump 22 and the second air/oil exchanger 23 are mounted on the second supply circuit 14b.
In this embodiment, the metering valve 19 is mounted on the second supply circuit 14b. The metering valve 19 is mounted between the supply pump 18 and the reducer 11, and comprises a single outlet connected to the lubrication enclosure 12. In this embodiment, the metering valve 19 has no function of distributing the flow rate between two outlets. The supply pump 18 is connected in bypass on the second circuit 14b between the valve 21, and in particular the second air/oil exchanger 23 when present, and the metering valve 19.
Advantageously, the metering valve 19 is able to open when the valve 21 is in the first position, allowing oil to be supplied to the reducer 11 from the main tank 15, and is able to remain open and/or close when the valve 21 is in the second position. Preferably, the metering valve 19 is able to close when the valve 21 is in the second position. This means that oil is not supplied to the reducer 11 from the auxiliary tank 20, but only the control system 13 is supplied from the auxiliary tank 20. In this way, the auxiliary tank 20 is sized to supply only the control system 13, making it less bulky.
Advantageously, the variable opening of the metering valve 19 is controlled by the electrical control unit 24. The electrical control unit 24 sends a signal to the metering valve 19 to open or close the latter depending on the operating phase.
The auxiliary tank 20 according to the invention is shown in
The auxiliary tank 20 comprises an enclosure 200. The enclosure 200 is made of metal, for example. The enclosure 200 is polygonal, for example. It comprises an upper wall 200a and a lower wall 200b connected by opposing transverse walls 200c, 200d. The transverse walls 200c, 200d may be parallel to each other. The upper wall 200a comprises, for example, a first segment 200a1 parallel to the lower wall 200b and a second segment 200a2 inclined towards the interior of the enclosure 200. The first segment 200a1 and the second segment 200a2 meet at a top O facing outwards from the enclosure 200. This configuration allows to optimise the flow of oil in the second supply circuit 14b during the second operating phase of the turbine engine 1, 1′, 1″. The top O represents a high point for the oil recovery, which normally eliminates the risk of air being present at this level in a negative gravity situation.
The enclosure 200 has a first outlet port 201 connected to the main tank 15 for example by a first pipe 201a, a second outlet port 202 connected to the second supply circuit 14b by the valve 21 or the auxiliary pump 22, an inlet port 203 connected to the control system by the oil recovery circuit 14b′ of the control system 13 and optionally a second inlet port 206 connected to the valve 21. The first outlet port 201 is formed, for example, on the transverse wall 200c and the first inlet port 203 is formed, for example, on the opposite transverse wall 200d. The second outlet port 202 is located on the upper wall 200a, for example on the top O.
The enclosure 200 has a total volume of, for example, between 2 L and 100 L, advantageously between 2 L and 40 L and preferably between 4 L and 30 L. The enclosure 200 comprises a first internal volume V1 in fluid communication with the first outlet port 201 and a second internal volume V2 in fluid communication with the second outlet port 202. The first internal volume V1 is between 1 L and 50 L, advantageously between 1 L and 20 L and even more advantageously between 2 L and 15 L. The second internal volume V2 is between 1 L and 50 L, advantageously between 1 L and 20 L and even more advantageously between 2 L and 15 L. Preferably, the first internal volume V1 is smaller than the second internal volume V2.
The auxiliary tank 20 also comprises a baffle 204 arranged in the enclosure 200 which separates the first internal volume V1 from the second internal volume V1. The baffle 204 comprises a first end wall 204a extending from the upper wall 200a towards the lower wall 200b and a second end wall 204b extending from the lower wall 200b towards the upper wall 200a. The first and second end walls 204a, 204b are for example parallel to the transverse walls 200c, 200d. The first and second end walls 204a, 204b are arranged between the first outlet port 201 and the second outlet port 202. The first end wall 204a and the lower wall 200b delimit a first fluid passage P1, and the second end wall 204b and the upper wall 200a delimit a second fluid passage P2. The fluid is, for example, air and/or oil.
The first end wall 204a and the second end wall 204b define an intermediate volume V3. In a first example, the sum of the first volume V1 and of the intermediate volume V3 is equal to the second internal volume V2. This allows to ensure that the internal volume V2 will contain only oil during the second phase of operation.
According to another example of embodiment, the sum of the volume of the pipe 201a connecting the first inlet port 201 to the main tank 15, the first volume V1 and the intermediate volume V3 is equal to the second internal volume V2. In this example, the sum of the first volume V1 and of the intermediate volume V3 is therefore less than the second internal volume V2. In addition, the volume of the pipe 201a can be dimensioned to be equal to the volume of oil consumed during the second phase of operation of the turbine engine 1, 1, 1″.
As illustrated in
During the first phase of operation of the turbine engine 1, 1, 1″, the auxiliary tank 20 is supplied with oil by the control system 13. The excess oil is transferred to the main tank 15. This transfer is provided by the pipe 201a. The control system 13 is supplied with oil from the main tank 15.
During the second operating phase of the turbine engine 1, 1, 1″, air enters the auxiliary tank 20 via the first outlet port 201. This is because the flow of oil exiting the tank is less than the flow entering it. However, thanks to the baffle 204, the passage of air from the first internal volume V1 towards the second internal volume V2 is slowed down. In this way, the supply pump 18 or the auxiliary pump 22 sucks in oil and not air or oil with a high air content, which allows to supply the control system 13 during the second operating phase. It is understood that, advantageously, the volume of the pipe 201a and of the baffle 204a is equal to the volume of oil leaving the second outlet aperture 202 during the second operating phase.
An auxiliary tank 20 of this type has the advantage of being simple and reliable. For example, such an auxiliary tank 20 does not implement any movable parts to manage the air intake from the main tank 15. For example, the first outlet port 201 can remain open and no closing member is implemented. The baffle 204 is also stationary, which is easily conceivable and allows to improve the reliability compared with a movable part such as a piston.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2110348 | Sep 2021 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2022/051809 | 9/27/2022 | WO |
