Systems and methods for controlling a change in a pitch angle of a turbine engine blade

Abstract

The invention relates to a system for controlling the change in the angle of inclination of the blades (13) of a fan of a turbomachine (10), in particular of an aircraft, the turbomachine (10) comprising blades (13) mounted radially in a drive shaft (11) and setting means (14) configured to change the angle of inclination (0) of the blades on the basis of an axial force (F) applied to the setting means (14). The control system comprises a hydraulic actuator (3), a hydraulic pump (4), a connecting ring (5) mechanically connected to the hydraulic pump (4) such that the flow rate of the hydraulic pump (4) is proportional to the relative speed between the drive shaft (11) and the connecting ring (5), and a magnetic coupling device (6) designed to control the drive speed of the connecting ring (5) in order to control the angle of inclination of the blades (13) independently of the speed of the drive shaft (11).

Description

Technical Field

[0001] This invention relates to a system for controlling the change in the tilt angle of turbine blades, the turbine comprising a plurality of blades having variable tilt angles. The blades should be understood as blades of a propeller in a turboprop engine and blades of a fan in a turbojet engine. Background Technology

[0002] For example, it is known to change the tilt angle of the blades to improve turbine performance and efficiency throughout all operational phases from takeoff to landing. This variable tilt angle allows for variations in the propeller or fan speed to specifically improve the propeller's propulsion efficiency without altering the turbine's propulsion efficiency, which is typically set at its continuous maximum speed. Furthermore, the blade tilting during landing reverses thrust, eliminating the need for complex and heavy conventional thrust reversal systems.

[0003] The difficulty of the tilt angle change control system lies in the fact that the blades belong to a rotating reference frame, and changing the blade angle requires the transfer of a large amount of energy in this rotating reference frame.

[0004] Current tilt angle change control systems typically include a hydraulic actuator that provides the necessary force to set the tilt angle to the desired angle (tilt). This hydraulic actuator operates within a rotating reference frame and is supplied by a hydraulic pump operating within a fixed reference frame. These systems are particularly complex, large in overall size, and have significant reliability issues, especially due to the use of rotary joints or connectors to transfer hydraulic fluid between the fixed and rotating reference frames. It is important to minimize leakage at the rotary joints, as the resulting pressure drop is compensated for by increasing pumping power, which affects the quality and efficiency of the actuation system.

[0005] Another solution is to use rotating electrical contacts to execute electrical commands for the electric actuator, but these contacts suffer from premature wear, which is problematic when they are difficult to access. Another solution is to execute electrical commands via a power transformer connected to the electric actuator, which necessitates providing a power transformer with a size similar to that of an electric motor, which is heavy, large in size, and expensive. Incidentally, in the prior art of patent application FR2831225A1, an electro-hydraulic device is known, comprising a hydraulic cylinder supplied by a hydraulic pump controlled by an electric motor, all within a rotating reference frame. The electric motor, within the rotating reference frame, is inductively controlled and powered by a control circuit within a fixed reference frame. The electric motor must have sufficient power to power the hydraulic pump. This electric motor adds mass to the rotating reference frame, which is a disadvantage. Besides the difficulty of transmitting power in a rotating reference frame, another difficulty is managing fault conditions during power transmission. Indeed, during a fault, it is necessary to place the propeller in a safe position to limit drag, as the fault results in loss of drive force and inability to hold the propeller stationary. Complete redundancy in rotational transfer is extremely detrimental to mass.

[0006] A system for controlling and changing the tilt angle of aircraft propeller blades is also known from the prior art of patent application US2699220A.

[0007] Therefore, the present invention aims to eliminate at least some of these disadvantages. Summary of the Invention

[0008] This invention relates to a system for controlling the change of the tilt angle of the blades of a turbine, particularly a fan of a turbine for an aircraft, the turbine including a drive shaft extending along a longitudinal axis adapted to be rotatably driven about the longitudinal axis relative to a fixed structure of the turbine, blades radially mounted relative to the drive shaft and adapted to be oriented at a blade tilt angle, and an orientation device configured to change the tilt angle of the blades according to an axial load applied to the orientation device. The control system includes a hydraulic actuator rotatably integrated with the drive shaft to apply an axial load to the orientation device and a hydraulic pump rotatably integrated with the drive shaft to power the hydraulic actuator to apply an axial load to the orientation device according to the flow rate of the hydraulic pump.

[0009] A significant feature of the invention is that the control system includes a connecting ring gear rotatably mounted about the longitudinal axis relative to a fixed structure of the turbine, the connecting ring gear being mechanically connected to a hydraulic pump such that the flow rate of the hydraulic pump is proportional to the relative speed between the drive shaft and the connecting ring gear, and a magnetic coupling device configured to guide the drive speed of the connecting ring gear so as to control the blade tilt angle independently of the speed of the drive shaft.

[0010] According to the invention, the energy supplied to the pump is derived from the drive shaft, which avoids the need for high power transmission required in the prior art. Advantageously, the blade angle can be easily adjusted by means of a brake-connected ring gear. The magnetic coupling device is easy to maintain and reliable due to its lack of contact. Advantageously, the fluid circuit is closed (no power supply) and belongs only to a rotating reference frame.

[0011] Preferably, the hydraulic actuator includes an actuator body comprising a first chamber and a second chamber configured to receive hydraulic fluid for translating the actuator body along a longitudinal axis according to pressure within the chambers. Preferably, a hydraulic pump is configured to supply fluid to the first chamber. Preferably, the hydraulic pump is configured to collect hydraulic fluid in the second chamber.

[0012] Preferably, the hydraulic pump is configured to move the hydraulic actuator in a first direction, particularly downstream, and the control system includes a return member configured to apply an axial return load in a second direction opposite to the first direction, particularly upstream. Advantageously, the return device is configured to reduce the tilt angle of the blades to a safe position. Thus, the return member performs a safety function by automatically reducing the tilt angle in the absence of hydraulic pressure. Advantageously, the fixing is passive. The return member is preferably in the form of a spring.

[0013] Preferably, in the absence of magnetic coupling, the connecting ring gear is rotatably driven by a hydraulic pump, particularly at the same rotational speed. Therefore, in order to create a speed difference, the coupling device should decelerate the connecting ring gear, which requires very little energy and also allows for energy harvesting.

[0014] Preferably, the magnetic coupling device includes a permanent magnet motor, which includes a stator component integrated with the fixed structure and a rotor component integrated with the connecting ring. The rotor component and the stator component are magnetically coupled to magnetically brake the ring gear.

[0015] According to one aspect of the invention, the magnetic coupling device further includes a control unit configured to provide a control current to the stator component in order to change the braking force.

[0016] Preferably, the control unit is integrated with the stationary structure. It can be advantageously housed in a compartment with favorable temperature and pressure conditions, which increases reliability and reduces cost.

[0017] According to a preferred embodiment, the control unit includes at least one variable resistor. This allows for easy setting of the braking force and the collection of heat and electrical energy during braking.

[0018] According to one aspect of the invention, the control system includes at least two hydraulic pumps, which are connected in series or in parallel. This provides redundancy and overall balancing.

[0019] According to one aspect of the invention, the control system includes at least one overspeed management system configured to change the power supply to the hydraulic actuator upon detecting overspeed. This ensures safety.

[0020] The present invention also relates to a turbine fan module including the control system described above.

[0021] The present invention also relates to a turbine, particularly a turbine for an aircraft, comprising a drive shaft extending along a longitudinal axis and adapted to be rotatably driven about the longitudinal axis relative to a fixed structure of the turbine, blades radially mounted in the drive shaft and adapted to be oriented at a blade tilt angle, and an orientation device configured to change the tilt angle of the blades according to an axial load applied to the orientation device. The turbine includes a control system as described above to apply the axial load to the orientation device.

[0022] The present invention also relates to a method for controlling the change of the tilt angle of turbine fan blades by means of the control system described above, the method comprising:

[0023] The steps of changing the drive speed of the connecting ring gear through a magnetic coupling device

[0024] The step of connecting the ring gear to drive the hydraulic pump is used to activate the hydraulic actuator and apply an axial load to the orientation device.

[0025] The steps of changing the tilt angle of the blades based on the axial load applied to the orientation device. Attached Figure Description

[0026] The invention will be better understood by reading the following description given as an example and by referring to the following drawings given as a non-limiting example, wherein the same reference numerals denote similar objects.

[0027] Figure 1 is a schematic longitudinal cross-section of a turbine according to an embodiment of the present invention.

[0028] Figure 2 shows a schematic longitudinal cross-section of the hydraulic actuator in the downstream position.

[0029] Figure 3 shows a schematic diagram of a longitudinal cross-sectional view of the hydraulic actuator in the upstream position.

[0030] Figure 4 is a schematic diagram of a method for controlling the blade tilt angle.

[0031] Figure 5 is a schematic diagram of the control unit of the magnetic coupling device.

[0032] Figure 6 is a schematic diagram of possible locations for installing the control unit in the turbine.

[0033] Figure 7 is a schematic diagram of a first alternative to a redundant control system.

[0034] Figure 8 is a schematic diagram of a second alternative to a redundant control system.

[0035] It should be noted that the accompanying drawings illustrate the invention in detail to facilitate its implementation, and the drawings can, of course, be used to better define the invention if necessary. Detailed Implementation

[0036] The invention will be described with respect to turboprop engines, but it is applicable to any turbine with rotating blades having a variable tilt angle, particularly turbojet engines with fans having rotating blades or turboprop engines with propellers having rotating blades. For brevity, the term "fan" will be used thereafter to refer to both turbojet engine fans and turboprop engine propellers.

[0037] The invention will then be described in conjunction with turboprop engines, but it is also applicable to turbojet engines.

[0038] Referring to FIG1, a partial cross-sectional view of a turboprop engine 10 according to an embodiment of the present invention is shown.

[0039] The turbine 10 includes a drive shaft 11 extending along a longitudinal axis X and adapted to be rotatably driven about the longitudinal axis X relative to the turbine 10, particularly via a fixed structure 12 with bearings 111. Subsequently, the terms "downstream" and "upstream" are determined relative to the longitudinal axis X, which in Figure 1 extends from downstream to upstream.

[0040] The turbine 10 includes a fan H, which includes blades 13 that are radially mounted relative to the drive shaft 11, particularly via a hub, and are adapted to be oriented at a tilt angle θ relative to a radial axis R orthogonal to the longitudinal axis X. The tilt angle θ then varies between a minimum tilt angle and a maximum tilt angle, at which the blades 13 are "feathered".

[0041] Referring again to FIG1, the turbine 10 includes an orientation device 14 configured to change the tilt angle θ of the blades 13 according to an axial load F applied to the orientation device 14. Such an orientation device 14 is known to those skilled in the art, particularly from patent application FR3036093. Preferably, the orientation device 14 includes a crank pin eccentric relative to the radial axis R.

[0042] In order to change the tilt angle of the blades 13, the turbine 10 includes a control system, which includes a hydraulic actuator 3, a hydraulic pump 4, a connecting ring gear 5, and a magnetic coupling device 6, which will be described in detail.

[0043] The hydraulic actuator 3 is configured to apply an axial load F to the orientation device 14. In this example, the hydraulic actuator 3 is in the form of a hydraulic cylinder, mounted outside the drive shaft 11, and rotatably integrated with it. In other words, the hydraulic actuator 3 belongs to a rotating reference frame.

[0044] In this example, hydraulic actuator 3 transmits oil, but it goes without saying that other hydraulic fluids can be considered.

[0045] Referring to Figure 1, the hydraulic actuator 3 includes an actuator body 30, which includes a first chamber 31 and a second chamber 32 configured to receive hydraulic fluid to translate the actuator body 30 along a longitudinal axis X according to the pressure in the chambers 31 and 32. In this embodiment, the first chamber 31 is located downstream of the second chamber 32. In this example, as will be explained later, the actuator body 30 moves downstream as the pressure in the first chamber 31 increases. The hydraulic actuator 3 also includes a calibration opening 33 that allows fluid to circulate from the first chamber 31 to the second chamber 32 at a controlled flow rate. The chambers 31 and 32 are separated by a wall belonging to the drive shaft 11.

[0046] In this example, the first chamber 31 is the supply chamber of the hydraulic pump 4, while the second chamber 32 is the collection chamber of the hydraulic pump 4. Therefore, the hydraulic pump 4 allows the actuator body 30 to move axially downstream.

[0047] In this example, the actuator body 30 moves between an upstream position at the end corresponding to the minimum tilt angle and a downstream position at the end corresponding to the maximum tilt angle.

[0048] Preferably, the hydraulic actuator 3 has a sensor configured to detect the position of the hydraulic actuator 3 and compare it with its setpoint position, as will be explained later.

[0049] Referring again to FIG1, the turbine 10 also includes a return member 7 configured to apply an upstream axial return load to the orientation device 14, i.e., in the opposite direction to the drive direction of the hydraulic pump 4.

[0050] Referring to Figure 1, in this example, the return member 7 is mounted around the drive shaft 11 between the stop member 112 of the drive shaft 11 and the actuator body 30, so as to apply stress directly upstream of the actuator body 30.

[0051] Therefore, when the hydraulic pressure in the first chamber 31 increases, the return member 7 makes it possible to resist downstream movement. When the first chamber 31 is no longer under pressure, the return member 7 allows the actuator body 30 to return upstream to a safe position by forcing fluid to circulate from the first chamber 31 to the second chamber 32 through the calibration opening 33. In other words, the return member 7 enables the blade 13 to be passively feathered.

[0052] As will be explained later, in the event of a control system failure, the return member 7 advantageously improves safety by reducing the tilt angle of the blade 13. In the absence of hydraulic pressure from the hydraulic pump 4, the blade 13 is advantageously brought back to a safe position (feathering blade).

[0053] Preferably, the return member 7 is in the form of a spring, but it goes without saying that it can be in other forms, such as a flexible rod or counterweights.

[0054] According to one aspect of the invention, the magnetic coupling device 6 is configured to rotatably connect the ring gear 5 in both directions, and thus dynamically control the axial position of the hydraulic actuator 3. This means that no unique return member is required.

[0055] Referring again to FIG1, the hydraulic pump 4 is rotatably integrated with the drive shaft 11 and supplies hydraulic actuator 3 to apply an axial load F to the orientation device 14 according to the flow rate of the hydraulic pump 4. Therefore, the hydraulic pump 4 and the hydraulic actuator 3 belong to the same rotating reference frame. The hydraulic pump 4 is connected to the first chamber 31 via a first supply channel 41 and to the second chamber 32 via a second collection channel 42. The hydraulic pump 4 is configured to increase the hydraulic pressure in the first chamber 31. In other words, the hydraulic pump 4 is configured to supply fluid to the first chamber 31 via the first supply channel 41. The fluid circulates into the second collection chamber 32 via a calibration opening 33 before being collected by the hydraulic pump 4 via the second collection channel 42. Therefore, the fluid circuit belongs only to the rotating reference frame, which limits the risk of leakage compared to prior art devices that require rotary joints to connect a fixed reference frame and a rotating reference frame.

[0056] Since channels 41 and 42 are rotating, the loop configuration of the fluid circuit advantageously avoids the occurrence of pressure differentials that would alter the equilibrium position of the hydraulic actuator 3. In fact, when the pressures of the entire fluid circuit are summed, the "rising" and "falling" pressures relative to the axis of rotation X are summed, resulting in a total zero value.

[0057] Preferably, the hydraulic pump 4 is a stationary volume pump, particularly a gear pump.

[0058] Referring to Figure 1, the hydraulic pump 4 includes a mechanical input 43 configured to receive input torque. Depending on the input torque applied to the mechanical input 43, the hydraulic pump 4 applies different flow rates in the first chamber 31, and thus applies different pressures. In other words, the hydraulic pump 4 makes it possible to convert the input torque into a flow rate setpoint, which advantageously alters the axial load F.

[0059] In this example, when the input torque is high, the hydraulic pump 4 increases the pressure in the first chamber 31, which moves the actuator body 30 downstream and compresses the return member 7, as shown in Figure 2. Conversely, as shown in Figure 3, when the input torque is low or zero, the hydraulic pump 4 does not provide any flow, and the pressure between chambers 31 and 32 is balanced by the return member 7. The return member 7 controls a small helix angle, and the vane 13 is in a safe position. This means that in the event of a failure of the hydraulic pump 4, safety is ensured by the return member 7.

[0060] Preferably, the mechanical input 43 is in the form of a drive pinion meshing with the connecting ring gear 5. Advantageously, the connecting ring gear 5 is only coupled to the hydraulic pump 4, such that the hydraulic pump 4 does not (or only slightly) supply hydraulic actuator 3 in the absence of magnetic coupling. The mechanical input 43 and the hydraulic pump 4 are mechanically coupled so that the mechanical input 43 rotatably drives the connecting ring gear 5 without magnetic coupling. In effect, the hydraulic pump 4 belongs to a rotating reference frame and is rotatably driven. As described below, the magnetic coupling device 6 makes it possible to magnetically brake the connecting ring gear 5 to create a speed difference between the connecting ring gear 5 and the hydraulic pump 4.

[0061] The connecting ring gear 5 is rotatably mounted relative to the fixed structure 12 of the turbine 10 about the longitudinal axis X, and is configured to provide input torque to the mechanical input 43 of the hydraulic pump 4. As shown in FIG1, the connecting ring gear 5 is connected to the fixed structure 12 via a bearing 51.

[0062] The connecting ring gear 5 is mechanically connected to the hydraulic pump 4 such that the flow rate of the hydraulic pump 4 is proportional to the relative speed between the drive shaft 11 and the connecting ring gear 5. As previously described, the hydraulic pump 4 is rotatably integrated with the drive shaft 11. Since the rotational speed of the drive shaft 11 is known, adjusting the rotational speed of the connecting ring gear 5 is sufficient to adjust the relative speed between the drive shaft 11 and the connecting ring gear 5, thereby changing the flow rate of the hydraulic pump 4. When the connecting ring gear 5 is rotatably driven by the hydraulic pump 4, braking the connecting ring gear 5 is sufficient to adjust the relative speed between the drive shaft 11 and the connecting ring gear 5.

[0063] The magnetic coupling device 6 is configured to change the driving speed of the connecting ring gear 5 about the longitudinal axis X, so as to indirectly control the tilt angle of the blade 13. In particular, the magnetic coupling device 6 performs a magnetic braking function for the connecting ring gear 5.

[0064] Referring to Figure 1, the magnetic coupling device 6 includes a permanent magnet motor 60, which includes a stator component 60A integrated with the fixed structure 12 and a rotor component 60B integrated with the connecting ring gear 5. The rotor component 60B is magnetically coupled to the stator component 60A. The magnetic coupling device 6 also includes a control unit 61 belonging to a fixed reference frame. The control unit 61 is configured to provide control current to the stator component 60A to change the rotational speed of the connecting ring gear 5.

[0065] Therefore, in summary, the control unit 61 can conveniently control the tilt angle θ of the blade 13. By keeping the hydraulic components (hydraulic actuator 3 and hydraulic pump 4) solely within a rotating reference frame, the non-contact magnetic connection between the fixed structure 12 and the connecting ring gear 5 reduces complexity. Furthermore, an electric motor is not required to control the hydraulic pump 4. The energy required for startup is directly taken from the drive shaft 11 via the connecting ring gear 5. This simplified power transmission also makes maintenance easier.

[0066] Preferably, for ease of maintenance, the magnetic coupling device 6 is configured to generate a rotating magnetic field to control the hydraulic actuator 3 when the turbine 10 stops. According to a preferred aspect, as previously described, the magnetic coupling device 6 is configured to generate a magnetic field rotating in both directions to dynamically control the upstream and downstream positions of the hydraulic actuator 3 without requiring the return member 7.

[0067] Alternatively, when the aircraft is on the ground, the auxiliary equipment can be connected to the magnetic coupling device 6 to generate a rotating magnetic field, thereby controlling the hydraulic actuator 3. In other words, the auxiliary equipment can be used during maintenance to check the operation of the control system.

[0068] The method for controlling the change in the tilt angle of blade 13 will now be described. In this embodiment, the permanent magnet motor 60 is initially deactivated, and the connecting ring gear 5 is rotatably integrated with the hydraulic pump 4, which itself is rotatably integrated with the drive shaft 11. The hydraulic pump 4 is not supplied, and there is no overpressure in the first chamber 31 of the hydraulic actuator 3. As shown in FIG3, the main body of the actuator 30 is constrained in the upstream position by the return member 7, thus minimizing the tilt angle θ.

[0069] In this example, the control unit 61 receives a command from, for example, a calculator of a turbine, to change the tilt angle of the blade 13.

[0070] Referring to Figure 4, the method includes the step of changing the electromotive force FEM in the E1 permanent magnet motor 60. The result is the step of changing the drive speed of the E2 connecting ring gear 5 via the magnetic coupling device 6. In this example, the permanent magnet motor 60 brakes the connecting ring gear 5. The relative speed between the hydraulic pump 4 and the connecting ring gear 5 increases.

[0071] The method includes the step of driving the E3 hydraulic pump 4 via the connecting ring gear 5 to activate the hydraulic actuator 3 and apply an axial load F to the orientation device 14. In practice, the hydraulic pump 4 is activated at a relative speed, supplying power to the first chamber 31 of the hydraulic actuator 3. The actuator body 30 moves downstream against the return member 7 and applies the axial load F to the orientation device 14, as shown in Figure 2.

[0072] This leads to the step of changing the tilt angle θ of the E4 blade 13 according to the axial load F applied to the orientation device 14. In this case, the tilt angle θ of the blade 13 increases to flatten the blade 13.

[0073] Therefore, the tilt angle θ of blade 13 can be easily controlled by setting the electromotive force FEM. Advantageously, the starting force of hydraulic pump 4 comes from drive shaft 11, which improves efficiency.

[0074] When the electromotive force FEM stops, the return force Fr of the return member 7 moves the hydraulic actuator 3 upstream, which changes the tilt angle θ of the blade 13 to the safe position shown in Figure 3. This ensures safety even if the magnetic coupling 6, the connecting ring gear 5, or the hydraulic pump 4 fails.

[0075] According to one aspect of the invention, referring to FIG5, the control unit 61 includes a variable resistor 62 to change the current flowing in the stator member 60A, thereby changing the rotational speed of the connected ring gear 5 to control the tilt angle θ of the blade 13.

[0076] Advantageously, when the hydraulic pump 4 is supplied, the permanent brake connecting the ring gear 5 generates current in the variable resistor 62, which can be collected and subsequently used. In fact, power generation is more important at very high tilt angles θ, i.e., at cruise power. Conversely, no energy is generated only at the feathering position (minimum tilt angle). A battery can be provided to store the electrical energy from the variable resistor 62 and distribute it to other equipment, such as a fuel pump. More preferably, a battery can also be provided to store the thermal energy from the variable resistor 62.

[0077] Preferably, the control unit 61 is located in a mild thermal environment, for example, near the turbine regulating calculator. For example, referring to FIG6, the control unit 61 may be located at different locations on the turbine, particularly in the nacelle (position P1) or downstream of the "core" area (position P2), located between the inner wall of the secondary flow and the outer wall of the primary flow.

[0078] According to one aspect of the invention, referring to FIG7, a first example of "series" redundancy is shown. In this figure, the turbine 10 includes a first hydraulic pump 4a connected to a first connecting ring gear 5a and a first magnetic coupling system 6a. Similarly, a second hydraulic pump 4b is shown connected to a second connecting ring gear 5b and a second magnetic coupling system 6b to provide redundancy.

[0079] The first chamber 31 of the hydraulic actuator 3 is supplied by a first supply channel 41, which is supplied by a first basic supply channel 41a connected to the first hydraulic pump 4a and by a second basic supply channel 41b connected to the second hydraulic pump 4b.

[0080] The second chamber 32 of the hydraulic actuator 3 is connected to the second collection channel 42. The second collection channel 42 is connected on one side to the first primary return collection channel 42a, which is connected to the first hydraulic pump 4a, and on the other side to the second primary collection channel 42b, which is connected to the second hydraulic pump 4b.

[0081] During normal operation, both the first hydraulic pump 4a and the second hydraulic pump 4b supply power to the first chamber 31 of the hydraulic actuator 3. Each magnetic coupling system 6a, 6b provides calibrated braking.

[0082] In the event of a malfunction, such as a short circuit in the second magnetic coupling system 6b that increases the electromotive force FEM, the second hydraulic pump 4b is actuated without a control command. This control causes the hydraulic actuator 3 to move downstream and causes the blade 13 to flatten, which is the opposite of "feathering" safety.

[0083] When the position of the hydraulic actuator 3 is detected to be different from the position setpoint, the first magnetic coupling system 6a minimizes its electromotive force as much as possible to reduce the flow rate of the first hydraulic pump 4a, thereby compensating for the increase caused by the second hydraulic pump 4b. This eliminates unnecessary movement of the hydraulic actuator 3. Advantageously, a failure of one of the hydraulic pumps 4a and 4b can be compensated for by using two hydraulic pumps 4a and 4b connected in series.

[0084] Optionally, to prevent one of the hydraulic pumps 4a and 4b from supplying flow, a check valve can be installed on one of the hydraulic pumps 4a and 4b. This allows the hydraulic actuator 3 to be actuated independently, with an actuation speed corresponding to the sum of the actuation speeds of the two hydraulic pumps 4a and 4b. Optionally, to prevent one of the hydraulic pumps 4a and 4b from controlling the hydraulic actuator 3 at a large tilt angle θ, an overspeed management mechanism known to those skilled in the art, i.e., the term "overspeed regulator" used in turboprop engines, can be provided. If the tilt angle θ becomes too low, the speed will increase and can be detected. These aspects will be described in detail later.

[0085] According to another aspect of the invention, referring to FIG8, a second example of "parallel" redundancy is shown.

[0086] In this figure, similar to the previous one, the turbine 10 includes a first hydraulic pump 4a connected to a first connecting ring gear 5a and a first magnetic coupling system 6a. Similarly, a second hydraulic pump 4b is shown connected to a second connecting ring gear 5b and a second magnetic coupling system 6b to provide redundancy.

[0087] The first chamber 31 of the hydraulic actuator 3 is supplied by a first supply channel 41, which is supplied by a first basic supply channel 41a connected to the first hydraulic pump 4a and by a second basic supply channel 41b connected to the second hydraulic pump 4b.

[0088] The second chamber 32 of the hydraulic actuator 3 is connected to a second collection channel 42, which is connected on one side to a first primary collection channel 42a, which is connected to a first hydraulic pump 4a, and on the other side to a second primary collection channel 42b, which is connected to a second hydraulic pump 4b. In this example, a first check valve 81 is installed in the first primary collection channel 42a, and a second check valve 82 is installed in the second primary collection channel 42b. These check valves 81 and 82 allow the two hydraulic pumps 4a and 4b to be used alternately in the event of a pressure loss in one of the hydraulic pumps 4a and 4b.

[0089] During normal operation, both the first hydraulic pump 4a and the second hydraulic pump 4b supply power to the first chamber 31 of the hydraulic actuator 3.

[0090] Referring again to Figure 8, an overspeed management mechanism comprising a first component 91 and a second component 92 is also present. The first component 91 is installed parallel to the first check valve 81 in the first basic collection channel 42a. The second component 92 of the overspeed management mechanism is installed in the second basic collection channel 42b, which is connected in series with the second check valve 82. Both the first component 91 and the second component 92 of the overspeed management mechanism are connected to the first basic supply channel 41a, as shown in Figure 8.

[0091] If one of the hydraulic pumps 4a and 4b fails, the overspeed management mechanism includes a speed detection component 93 that controls the first component 91 and / or the second component 92 above a predetermined speed threshold to transfer the supply to the first chamber 31 and place the vane 13 in a safe position. Preferably, the speed detection component 93 includes a centrifugal force-sensitive counterweight with a return component mounted on it to determine the speed threshold. Preferably, each component 91, 92 is in the form of a sliding valve core to directly connect the inlet and return channels of the hydraulic pumps 4a, 4b in the event of overspeed. In other words, each component 91, 92 includes at least two positions controlled by the speed detection component 93 (by-position and safe deflection position). This prevents any unnecessary control of the tilt angle θ. Of course, several counterweights can be used on several spools.

[0092] When using two hydraulic pumps 4a and 4b, they are preferably positioned radially opposite each other to reduce imbalance.

Claims

1. A control system for controlling the tilt angle of the blades (13) of a fan in a turbine (10), The turbine (10) includes A drive shaft (11) extends along a longitudinal axis (X) and is adapted to be rotatably driven about the longitudinal axis (X) relative to a fixed structure (12) of the turbine (10). The blade (13) is radially mounted relative to the drive shaft (11) and is adapted to be oriented at a blade tilt angle (θ). Orientation device (14) configured to control the tilt angle (θ) of the blade according to the axial load (F) applied to the orientation device (14). The control system includes A hydraulic actuator (3) is rotatably integrated with the drive shaft (11) to apply an axial load (F) to the orientation device (14). A hydraulic pump (4), which is rotatably integrated with the drive shaft (11), supplies hydraulic actuator (3) to apply an axial load (F) to the orientation device (14) according to the flow rate of the hydraulic pump (4). The control system is characterized in that it includes A connecting ring gear (5) is mounted rotatably about the longitudinal axis (X) relative to the fixed structure (12) of the turbine (10), and the connecting ring gear (5) is mechanically connected to a hydraulic pump (4) such that the flow rate of the hydraulic pump (4) is proportional to the relative speed between the drive shaft (11) and the connecting ring gear (5). The magnetic coupling device (6) is configured to guide the drive speed of the connecting ring gear (5) so as to control the tilt angle of the blade (13) independently of the speed of the drive shaft (11).

2. The control system according to claim 1, wherein, The hydraulic actuator (3) includes an actuator body (30) having a first chamber (31) and a second chamber (32), the first chamber (31) and the second chamber (32) being configured to receive hydraulic fluid so as to translate the actuator body (30) along the longitudinal axis X according to the pressure in the chambers (31, 32).

3. The control system according to claim 1, wherein, The hydraulic pump (4) is configured to move the hydraulic actuator (3) in a first direction, and the control system includes a return member (7) configured to apply an axial return load (Fr) in a second direction opposite to the first direction.

4. The control system according to claim 1, wherein, Without magnetic coupling, the connecting ring gear (5) is rotatably driven by the hydraulic pump (4).

5. The control system according to claim 1, wherein, The magnetic connection device (6) includes a permanent magnet motor (60), which includes a stator component (60A) integrated with the fixed structure (12) and a rotor component (60B) integrated with the connecting ring gear (5). The rotor component (60B) is magnetically connected to the stator component (60A), thereby magnetically braking the connecting ring gear (5).

6. The control system according to claim 5, wherein, The magnetic coupling device (6) further includes a control unit (61) configured to provide a control current to the stator component (60A) in order to change the braking force.

7. The control system according to claim 6, wherein, The control unit (61) is integrated with the fixed structure (12).

8. The control system according to claim 6, wherein, The control unit (61) includes at least one variable resistor (62).

9. The control system according to claim 1, comprising at least two hydraulic pumps (4a, 4b).

10. The control system of claim 9, comprising at least one overspeed management system configured to control the power supply to the hydraulic actuator (3) upon detection of overspeed.

11. A turbine (10) comprising a control system according to any one of claims 1 to 10.

12. A method for controlling the change of the tilt angle of the blades (13) of a fan of a turbine (10) using a control system according to any one of claims 1 to 10, the method comprising: The step of changing the driving speed of the connecting ring gear (5) by means of the magnetic coupling device (6) The step of driving the hydraulic pump (4) by connecting the ring gear (5) activates the hydraulic actuator (3) and applies an axial load (F) to the orientation device (14), and The step of changing the tilt angle (θ) of the blade according to the axial load (F) applied to the orientation device (14).

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