Automatic blade pitch control

Abstract

The invention relates to a method for controlling the pitch angle of the blades or vanes of a propulsion body of a turbine engine, the method comprising: controlling the pitch angle of the blades or vanes of a propulsion body of a turbine engine according to the rotation speed (XN 测量 ) and speed setting value (XN 设定 ) to generate the pitch command (i 最终 ), the method comprises a normal regulation chain (13) and an abnormal regulation chain (16), in which the pitch command is also based on the value of the pitch angle (β 测量 ) is generated, in an abnormal regulation chain, the pitch command is generated independently of the value of the pitch angle of the blades or blades of the propulsion body.

Description

Technical Field

[0001] The present invention relates to the general technical field of turbomachines and, more particularly, to turbomachines comprising a propeller or fan with a variable setting, such as a turbomachine with two unducted contra-rotating propellers (commonly known as open rotors), or a turbojet engine with a ducted fan of the VPF (Variable Pitch Fan) type, the blades of which have a variable setting and are optionally intended to be able to operate in thrust reversal mode (reversal of the direction of air passing through the fan). Background Art

[0002] Turbines are typically equipped with a power control system capable of controlling the variation of various parameters (e.g., fuel flow, or the setting angle of the fan blades or propeller blades) to adapt the turbine power to the flight phase. In the remainder of this text, the example of a propeller as an automated propulsion element will generally be used, but it should be understood that automation can be applied to any propulsion element, including a fan or propeller. Furthermore, it is assumed that the blades or vanes of the propulsion element are designed to have a uniform setting angle.

[0003] As in Figure 2 As shown in FIG, a conventional strategy for automatically regulating the rotational speed of a propeller consists in using a cascade control with a plurality of nested controllers:

[0004] - an advanced controller 1 based on a measurement of the rotational speed of the engine 2 driving the propeller XN 测量 To control the setting β, thus automatically adjusting the propeller speed XN,

[0005] - Local controller 3, which returns β by modifying the position of device 4 based on the settings 测量 To control the setting modification device 4, thereby automatically adjusting the setting angle β.

[0006] In such a system, setting modification means 4 act on the setting β of the blades or vanes of a propulsion element (fan or propeller) in order to vary the rotation speed XN of this propulsion element.

[0007] The setting measuring device 5 obtains the setting measurement value β at the output of the setting modifying device 4 测量 , this setting measures the value β 测量 is returned to the local controller 3.

[0008] The measurement of the setting angle can be done directly by measuring the angle directly, or indirectly by measuring another parameter that is a "mirror" of the setting angle. For example, the position of the actuator will be represented as the setting angle by a line of motion.

[0009] The speed measuring device 6 obtains the speed measurement value XN at the outlet of the engine 2 测量 , speed measurement value XN 测量 is returned to the high-level controller 1.

[0010] Speed ​​measurement value XN 测量 and speed setting value XN 设定 is sent to the high-level controller 1, which sends the setpoint value β as an output 设定 .

[0011] Set the setpoint β 设定 and set the measured value β 测量 is sent to the local controller 3 , which sends as output a command i, which is sent to the setting modification device 4 .

[0012] The problem with this strategy is that, in the event of a failure of the setting measuring device 5 , the loop of the local controller 3 is no longer operational, thereby rendering the loop of the superordinate controller 1 inoperable.

[0013] Normally, in the event of loss of the set-measure line, the engine is controlled in an open loop as a safety measure, usually by returning the engine speed to idle and feathering the blades or vanes of the propulsion element. This return to open loop is dangerous, as the connection between the propulsion section of the engine and the gas generator has been lost:

[0014] - there is a high risk of overtorque if the setting is reduced too quickly (propeller speed decreases) while the engine power is still high;

[0015] - When the propeller's position is not measured, there is a risk that if the propeller is not quickly arranged in a safe position, the propeller will enter a region of aerodynamic stall (excitation of oscillation modes) or even unexpected reversal (an event classified as catastrophic).

[0016] Furthermore, in any case, this adjustment translates into a loss of thrust and a loss of thrust control. Summary of the Invention

[0017] It is an object of the present invention to provide an instrument and a control for setting a propeller with a variable setting even in the event of loss of the setting measurement line.

[0018] The present invention provides a method for controlling the setting angle of the blades or vanes of a propulsion element of a turbine, the method comprising generating a setting command based on the rotational speed and the rotational speed set value of the propeller, the method comprising a normal control line and a degraded control line, in which the setting command is also generated based on the value of the setting angle of the blades or vanes of the propulsion element, and in which the setting command is generated independently of the value of the setting angle of the blades or vanes of the propulsion element.

[0019] This allows the propeller speed to continue to be controlled even with the added limitations associated with removing the local circuit (e.g., during a fault that renders the normal control line inoperable), thus enabling the failure to be avoided by operating the engine differently. Thus, it is conceivable to continue operating the engine normally during stable speed periods and only modify the command mode during transient speed periods, thus enabling continued engine operation.

[0020] Advantageously, the present invention is accomplished by the following features, taken alone or in combination:

[0021] - The method further comprises the step of selecting a degraded control line or a normal control line;

[0022] - the method further comprises a command return step configured to return the setting command to at least one of the normal control line and the degraded control line; this ensures the continuity of the setting angle command when switching between the normal control line and the degraded control line;

[0023] - a normal control line comprising a first controller configured to provide a setpoint value based on a speed setpoint value and a speed measurement value, and a second controller configured to provide a degrade command based on the setpoint value and the setpoint measurement value;

[0024] - the command return line is configured to return the setting command to at least one of the second controller and the degradation control line, and the second controller is configured to provide the degradation command based on the setting setpoint, the setting measurement value, and the setting command;

[0025] the speed setpoint is a function of the power produced by the turbine and can be varied between a lower limit configured to avoid excessive torque at the propeller and an upper limit configured to avoid aerodynamic stall of the propeller;

[0026] The speed setpoint has a limited gradient; this makes it possible to limit setpoint variations and thus smooth the command curve, which increases the safety of the driving mode.

[0027] According to another aspect, the invention provides a control device for controlling the setting of a propeller of a turbomachine, the turbomachine comprising an actuator configured to modify the setting angle of the propeller, the control device comprising:

[0028] -Controller,

[0029] a first sensor configured to determine the value of the setting angle of the propeller;

[0030] a second sensor configured to determine the rotational speed of the propeller;

[0031] The controller is configured to:

[0032] - in normal control mode, providing normal setting commands to the actuators according to the rotational speed of the propeller, the value of the setting angle and the speed setting value;

[0033] - in degraded control mode, providing degraded setting commands to the actuators as a function of the propeller's rotational speed and the speed setpoint, regardless of the value of the setting angle;

[0034] The control device further includes a selector configured to select a normal control mode or a degraded control mode of the controller.

[0035] According to another aspect, the invention provides a turbomachine comprising a propeller with a variable setting and a control device according to the invention for controlling the setting, wherein a controller performs the method according to the invention for controlling the setting.

[0036] According to another aspect, the invention provides an aircraft comprising a turbine according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Other characteristics and advantages of the present invention will become more apparent from the following description, which is purely illustrative and non-limiting and must be read with reference to the accompanying drawings, in which:

[0038] Figure 1 is a schematic model of the architecture of a prior art system for controlling the setting of propeller blades;

[0039] Figure 2 is a schematic model of the architecture of a system for controlling the setting of blades of a propeller according to the present invention;

[0040] Figure 3 is a schematic model of the functional structure of a macro controller of a system for controlling the setting of blades of a propeller according to the present invention;

[0041] Figure 4is a schematic model of a turbine with variably set propellers, such as a turbine with twin unducted fans (commonly known as "open rotors"). DETAILED DESCRIPTION

[0042] Reference Figure 2 , an embodiment of the speed control system 7 includes:

[0043] a setting modification actuator 8 configured to modify the setting of the propeller in dependence on the propeller setting modification setpoint;

[0044] a turbine 9 configured to rotationally drive a propeller;

[0045] a first sensor 10 configured to measure the setting angle of the propeller;

[0046] a second sensor 11 configured to measure the rotational speed of the propeller;

[0047] - A controller 12 configured to issue a command i to set the speed according to the speed setting value XN 设定 , the value of the setting angle β measured by the first sensor 10 测量 , and the measured value XN of the rotation speed sent by the second sensor 11 测量 to change the propeller settings.

[0048] Reference Figure 3 , the controller 12 includes:

[0049] - Normal control line 13, which includes a first control command 14 and a second control step 15, wherein the first control command 14 is configured to be set according to the speed setting value XN 设定 and the speed measurement value XN 测量 To generate settings to modify the set value β 设定 , the second control step 15 is configured to set the measured value β according to 测量 and set to modify the set value β 设定 To generate the normal setting value iβ;

[0050] - a degraded control line 16 comprising a third control step 17 configured to control the rotational speed setpoint XN 设定 and the speed measurement value XN 测量 To generate the degraded setting value iXN;

[0051] A selector 18 configured to select a control line from the normal control line 13 and the degraded control line 16 , the selector 18 being triggered by receiving a fault signal resulting in the selection of the degraded control line 16 .

[0052] Fault signals are generated during fault detection, which can be accomplished through the following process:

[0053] - Perform range tests on the acquired values ​​of the setting angles to ensure that the measured values ​​are reasonable. These range tests can be connected to the sensor (measurement range) or the engine (at a specific operating point, the setting angle is expected to be in a certain range);

[0054] - Deviation test between channels: The acquisition is usually done in duplicate, which ensures that both measurements are consistent.

[0055] If the measured values ​​do not agree, a fault is considered detected.

[0056] This management by the controller 12 makes it possible to continue to control the propeller speed even with the added limitations associated with the removal of the local circuit, for example during a fault that renders the normal control line 13 inoperable.

[0057] In particular, for turboprop engines with variable setting fans, or turbojets with VPF type unducted fans whose blades have variable setting and are optionally designed to be able to operate in thrust reversal mode, or twin-propeller unducted turboprop engines commonly known as "open rotors", this configuration makes it possible to increase the robustness of the setting angle measurement in the presence of faults.

[0058] In a preferred embodiment, the controller 12 includes a return step 19 configured to set the command i 最终 :

[0059] - Return to the second control step 15 , which makes it possible to ensure the continuity of the normal setpoint iβ;

[0060] - Return to the third control step 17 , which makes it possible to ensure the continuity of the degraded setpoint iXN;

[0061] Preferably, a return is made to the second control step 15 and the third control step 17, which makes it possible to ensure the continuity of the normal set value iβ, the degraded set value iXN, and the normal output iβ and the degraded output iXN with each other, so that the output of the controller 12 is continuous even when the selector 18 switches from the normal control line 13 to the degraded control line 16, or conversely from the degraded control line to the normal control line if a fault is recovered.

[0062] Specifically, therefore, control lines not selected by the selector 18 are continuously updated to avoid sudden changes in set values ​​when the unselected control lines are selected. Here, the term “selected” should be understood to mean that the control lines are connected to the output of the controller 12 through the selector 18.

[0063] When the control system 7 is arranged in conjunction with a turbine comprising a propeller with a variable setting, e.g. Figure 4 When associated with an "open rotor" turbine 20 shown in FIG. 1 , which turbine comprises at least one rotor 21 equipped with a plurality of blades 22 having variable settings, the assembly can be implemented in two operating modes.

[0064] The gas generator 9 , which is formed by the low-pressure and / or high-pressure shaft of the turbine and comprises at least one compressor and at least one turbine, rotationally drives the rotor 21 and generates a constant power defined by the driver or an autonomous driving method.

[0065] Depending on the flight phase envisaged (e.g. climb, descent or cruise flight), the rotation speed of the rotor 21 can be varied to optimize the propulsive efficiency of the blades 22. Therefore, it may be decided to modify the setting of the blades 22 in order to change the forces exerted by the air on the blades 22, thereby modifying the torque applied to the rotor and the rotation speed of said rotor 21.

[0066] In the case of normal operation, the normal control line 13 is selected.

[0067] The first sensor 10 (at Figure 4 The first sensor 11 measures the rotational speed of the rotor 21 and returns this information to the controller 12.

[0068] According to the thrust required in the flight phase, the speed setting value XN 设定 is sent to the controller 12.

[0069] The first control step 14 controls the speed setting value XN 设定 and the speed measurement value XN 测量 Based on the observed difference, in the second control step 15, the first control module 14 sends a setting to modify the set value β 设定 .

[0070] The second control step 15 sets the modified set value β 设定 and set the measured value β 测量 A comparison is made and a set command current iβ is sent according to the observed difference.

[0071] The setting modification actuator 8 modifies the setting β of the blades 22 according to the received setting command current iβ, which has the effect of modifying the rotational speed XN of the rotor 22 .

[0072] In the event of a failure of the normal control line 13 (eg, a failure of the first sensor 10), the selector 18 switches to the degraded control line 16. The third control step 17 is configured to omit setting the measured value β测量 , and based on the speed setting value XN 设定 and the speed measurement value XN 测量 The deviation between φ and φ is used to directly control the setting modifying actuator 8. Therefore, the controller 12 is specially designed to process this input-output pair and send a signal for controlling the highly dynamic setting modifying actuator 8.

[0073] The unselected control lines use feedback 19 to keep consistent with the state of the system. The principle of feedback is to reconstruct the internal state of the unselected control lines so that if the unselected control lines are enabled, they will produce the same output. Therefore, the selected command current i 最终 (The selected command current is sent to the actuator 8 .) In this way, when there is a switch from one control line to another, the transition is smooth without any abrupt changes in the command signal.

[0074] When the normal control line 13 is disabled, the software setting stop is removed because it utilizes the setting measurement value so that the setting setpoint is limited when the minimum setting stop is reached, and the software setting stop is configured to be the least restrictive usable setting.

[0075] This protection is particularly useful when the propeller speed setting is not adapted to the power produced by the engine. Thus, the controller 12 may request a low setting without any protection preventing the controller from doing so, which could place the propeller in the aerodynamic stall region.

[0076] It is therefore necessary to have an adaptive power control for reducing as much as possible the risk of having a propeller speed setpoint that is too high in relation to the power produced by the engine.

[0077] Therefore, depending on the power of the engine, a minimum-maximum type limitation is applied to the speed setpoint XN 设定 :

[0078] - A minimum threshold for the speed setpoint prevents excessive torque, which occurs when the power generated by the engine cannot be converted by the propeller due to a setting too high;

[0079] - Maximum threshold for the speed setpoint to prevent entering the aerodynamic stall region.

[0080] These constraints are related to the blade and engine design and are input data provided by the designer.

[0081] Power management must be developed to account for the additional constraints associated with disabling the normal control line 13 when enabling the degraded control line 16 .

[0082] In particular, the dynamic limitation of the set angle is no longer controlled by the normal control line 13, so it is necessary to adjust the speed setpoint XN by reducing the gradient of the setpoint. 设定 .

[0083] The setpoint gradient is determined based on the dynamic limits of the setting angle, which are known and defined for normal operation, and the relationship between the speed and the setting, which is known at design time. The dynamic limits of the speed can therefore be determined optionally by adding a safety margin.

[0084] Various drive methods are conceivable to handle the adjustment of the rotational speed setpoint.

[0085] In the first drive mode, the engine continues normal operation with the speed setpoint adjusted. Control of the speed enables the engine to continue operating. The engine operates normally and provides thrust during stable speed periods. During transient speed periods, speed setpoint adjustments are moderated by limiting changes, which enables the engine to continue operating and avoids loss of thrust control. This allows the flight to be completed under normal circumstances by avoiding loss of thrust control, allowing maintenance to be performed once on the ground. The first drive mode is preferred when the propeller can be driven with healthy behavior, meaning that changes in the settings result in a monotonic change in the propeller speed. This allows the engine to remain operational.

[0086] In the second drive mode, the control of the speed setpoint allows a safe return to a safe position. This reduces the risk of engine failure at the expense of thrust control. This second drive mode is preferably used when the propeller may be driven in a manner that is considered unhealthy.

[0087] In a third drive mode, used when the propeller is not drivable, command current is applied directly to the actuator without any control of the rotational speed, thus returning to the feathered idle state in an open loop.

Claims

1. A method for controlling the pitch angle of a blade or vane of a propulsion element of a turbine, the method comprising generating a pitch command as a function of the rotational speed of a propeller and a rotational speed setpoint, the method being characterized in that the method comprises a normal control line (13) in which the pitch command is also generated as a function of the pitch measurement of the blade or vane of the propulsion element, and a degraded control line (16) in which the pitch command is generated independently of the pitch measurement of the blade or vane of the propulsion element. 2 . The method according to claim 1 , further comprising the step of selecting the degraded control line or the normal control line. 3 . The method according to claim 1 , further comprising a command return step configured to return the pitch command to at least one of the normal control line and the degraded control line. 4 .

4. The method according to claim 1 or 2, wherein: The normal control line includes a first controller configured to provide a pitch setpoint based on the rotational speed setpoint and the rotational speed measurement, and a second controller configured to provide a degraded command based on the pitch setpoint and the pitch measurement.

5. The method according to claim 4, wherein: The method also includes a command return step, which is configured to return the pitch command to at least one of the normal control line and the degraded control line, and the command return line is configured to return the pitch command to at least one of the second controller and the degraded control line, and wherein the second controller is configured to provide the degraded command based on the pitch set value, the pitch measurement value and the pitch command.

6. The method according to claim 1 or 2, wherein: The speed setpoint is a function of the power produced by the turbine and is variable between a lower limit configured to avoid excessive torque at the propeller and an upper limit configured to avoid aerodynamic stall of the propeller.

7. The method according to claim 1 or 2, wherein: The rotational speed setpoint has a limited gradient.

8. A control device for controlling the pitch of a propeller of a turbomachine, the turbomachine comprising an actuator (8) configured to modify the pitch angle of the propeller, the control device comprising: - a controller (12), - a first sensor (10) configured to determine a pitch measurement of the propeller; - a second sensor (11) configured to determine the rotation speed of the propeller; The controller (12) is configured to: - in a normal control mode (13), providing a normal pitch command to the actuator based on the rotational speed of the propeller, the pitch measurement value, and the speed setpoint; - in a degraded control mode (16), providing a degraded pitch command to the actuator, independently of the pitch measurement value and depending on the rotational speed and the rotational speed setpoint of the propeller; the control device also includes a selector (18) configured to select the normal control mode (13) or the degraded control mode (16) of the controller (12).

9. A turbine comprising a propeller with a variable pitch and a control device for controlling the pitch according to claim 8, wherein: The controller (12) executes the method for controlling the pitch according to any one of claims 1 to 7.

10. An aircraft comprising a turbine according to claim 9.

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