System for controlling the cyclic setting of blades

Abstract

The present invention describes a system for controlling the cyclic pitch of the blades (1) of a propeller of a turbomachine, the blades (1) being arranged in a plane orthogonal to the axis of rotation (r) of the propeller, the system comprising: - a plate assembly (40) capable of tilting relative to the orthogonal plane (P), - a hinge system (50) that hinges the plate assembly (40) relative to the blade (1) such that tilting of the plate assembly (40) changes the pitch of the blade (1), - a force sensor (5) designed to measure the force exerted by the air flow at the inlet of the blades (1) of the propeller in the orthogonal plane (P), - a cylinder (60) adapted to tilt the plate assembly (40) in response to the force measured by the force sensor (5).

Description

Field of the Invention

[0001] The present invention relates to the field of systems for controlling the cyclic pitch of the blades of a turbine propeller. Background of the Invention

[0002] The airflow at the inlet of the blades of a turbine propeller of an aircraft can have an angle of attack relative to the axis of rotation of the blades, which corresponds to the longitudinal axis of the turbine. Thus, the blades of the propeller of the turbine or the blades of the fan of the turbine undergo a non-uniform distribution of the airflow during the rotation of these blades about the longitudinal axis.

[0003] This angle of attack can be the result of predictable phases (such as the incidence phase or the maneuver phase) during climb, descent or turn, which may cause the sideslip of the aircraft. This angle of attack can also be the result of unpredictable phases (such as the crosswind phase). Figure 1a An aircraft in the cruise phase at a stable altitude is shown, for example, and the airflow F at the inlet of the blade 1 of the propeller is directed in the longitudinal direction corresponding to the axis of rotation r of the propeller. Figure 1b An aircraft in the climb phase is shown, and the airflow F includes a longitudinal component directed along the axis of rotation of the propeller and a transverse component in a plane perpendicular to the axis of rotation r of the propeller.

[0004] This angle of attack corresponding to the non-uniform distribution of the airflow on the blade causes an asymmetry in the lift and drag of the blade, and thus an asymmetry in the thrust of the blade. Thus, the thrust includes a longitudinal component, but also includes a transverse component corresponding to lateral parasite forces and vertical parasite forces, i.e., a transverse component directed in an orthogonal plane perpendicular to the longitudinal axis.

[0005] In addition to the loss of thrust generated, these parasite forces also cause a parasite moment applied to the blade, which is known as the "1P moment" in the aviation field.

[0006] The 1P moment is determined for the mass of the blade structure of the turbine and a set of components providing the attachment of the propeller to the aircraft. In fact, the mass of these components is determined to ensure the resistance of these components to the 1P moment: thus an increase in the 1P moment leads to an increase in the mass of these components. In addition, a large 1P moment may increase wear, thus reducing the life of the propeller and the components providing the attachment of the engine to the aircraft, which requires additional maintenance and component replacement operations.

[0007] The 1P moment due to non-uniform airflows has an impact on shrouded architectures (such as turbofan engines), despite the straightening effect of nacelle convection. In particular, this phenomenon exists in turbofan engines with a high bypass ratio and thus a very large fan propeller diameter. A shrouded turbofan engine is shown, for example, in Figure 2a as shown.

[0008] In particular, the 1P moment is determined for unshrouded architectures (such as turboprop engines or open rotor engines), which allow an increase in the bypass ratio with respect to conventional turbofan engines. An open rotor engine is illustrated by way of example in Figure 2b For these unshrouded architectures, the 1P moment is very important for the structure of the propeller as well as for the optimization of the operation of the propeller.

[0009] The 1P moment is also determined for buried engines, where asymmetry can occur between the covered and free parts of the propeller.

[0010] The pitch of the blades of the propeller can be controlled so as to reduce the 1P moment by redirecting the thrust in the longitudinal direction. The pitch of the blade corresponds to the angle formed between an axis connecting the leading edge and the trailing edge of the blade on the one hand and the axis of rotation of the propeller on the other hand.

[0011] Systems for controlling the collective pitch of the blades, which are capable of changing the pitch of the set of blades identically, are known. Thus, all the blades have the same pitch. In particular, a cylinder can cause a longitudinal displacement of a disk articulated relative to the blade by means of a connecting rod, and the longitudinal displacement of the disk causes an overall change in the pitch of the blade. However, these systems are not able to reduce the 1P moment due to the non-uniform distribution of the airflow over the blades. Thus, these systems are suitable for flight phases without crosswinds at a stable altitude, but not for maneuvering phases, approach phases or crosswind phases.

[0012] Systems for controlling the cyclic pitch of the blades are also known from the prior art. These systems are capable of applying a pitch that varies periodically according to the angular position of the blade around the axis of rotation to each blade, and each blade has its own specific pitch. By optimizing the pitch of the blades with respect to the incident flow, the pitch is adapted to cancel out the 1P moment in order to generate longitudinal thrust.

[0013] Such systems exist in particular in the field of helicopters. However, these systems are not suitable for the constraints, requirements and architectures encountered in other aircraft (such as airplanes).

[0014] A system for controlling the cyclic pitch of a propeller is described in document FR 2 996 591. The blades are fixed to two disks which are mounted to rotate with the hub of the propeller. Four cylinders can tilt one of the disks relative to the other, which results in the cyclic pitch of the blades. However, the blades are directly fixed to the two disks at the attachment points, and the two disks rotate integrally with the propeller, which strongly constrains the position of the device. In addition, the described control system does not allow for active control of the cyclic pitch of the blades according to the forces encountered by the aircraft during flight.

[0015] A system for passive adjustment of the cyclic pitch of the blades of an unshrouded propeller is described in French patent application n o 17552851. In this system, a connecting rod is fixed on the one hand to the blade and on the other hand to a tiltable disk. A non-longitudinal air flow generates forces on the blade that tend to change the pitch of the blade, and the connecting rod in turn exerts forces on the disk that tend to change the inclination of the disk until the forces in the orthogonal plane cancel each other out. However, this system does not allow for active control of the cyclic pitch of the blades, nor does it allow for adjustment of the sensitivity of the change in the pitch of the blades according to the forces in the orthogonal plane.

[0016] Finally, a system for controlling the cyclic pitch of an unshrouded propeller is described in document FR 2 997 138. At least three cylinders change the inclination of the articulated parts relative to the blades such that the displacement of the cylinders produces a periodic change in the pitch of the blades. The pitch of the blades is determined by a prior simulation to reduce losses caused by obstacles (such as wings or fuselages) that are known in advance. However, this system requires prior knowledge and simulation of flow non-uniformities and does not allow for real-time adjustment of the pitch of the blades according to the phases and evolution of the flow non-uniformities encountered by the aircraft during flight. Summary of the Invention

[0017] An object of the present invention is to propose a system for controlling the cyclic pitch of blades, which makes it possible to reduce the disturbing forces and moments generated on the blades due to the non-uniform distribution of the air flow on the blades.

[0018] Another object of the present invention is to propose a system for controlling the cyclic pitch of blades, which is suitable for implementation on a shrouded propeller or an unshrouded propeller of a turbine.

[0019] Another object of the present invention is to propose a system for controlling the cyclic pitch of blades, which makes it possible to adjust the pitch in real time during flight.

[0020] According to a first aspect, the present invention relates to a system for controlling the cyclic pitch of the blades of a propeller of a turbine, the propeller comprising a set of blades that are rotatably movable about a rotation axis relative to a stator reference system of the turbine, the blades being arranged in a plane orthogonal to the rotation axis of the propeller, this plane being called the orthogonal plane, the system being characterized in that the system comprises:

[0021] - a plate assembly that is capable of tilting relative to the orthogonal plane,

[0022] - a hinge system that hinges the plate assembly to the blade such that tilting of the plate assembly causes a periodic change in the pitch of the blade,

[0023] and the system comprises:

[0024] - a force sensor that is mounted fixed in the stator reference system and is adapted to measure the force exerted in the orthogonal plane by the air flow at the inlet of the blades of the propeller,

[0025] - a cylinder that is adapted to tilt the plate assembly and is adapted to be actuated in response to the force measured by the force sensor.

[0026] The following are some preferred but non-limiting features of the system for controlling cyclic pitch described above, which are taken individually or in combination:

[0027] - The force sensor comprises a strain gauge and is adapted to be positioned at a bearing support of the intermediate housing of the turbine;

[0028] - The system comprises a first set of force sensors and a second set of force sensors, the first set of force sensors being adapted to measure the force in a first direction of the orthogonal plane, the second set of force sensors being adapted to measure the force in a second direction of the orthogonal plane, the second direction being perpendicular to the first direction, the system further comprising a first cylinder and a second cylinder, the first cylinder being adapted to be actuated in response to the force measured by the first set of force sensors, and the second cylinder being adapted to be actuated in response to the force measured by the second set of force sensors;

[0029] - The plate assembly comprises an inner plate and an outer plate, the inner plate being mounted fixed in the stator reference system, the outer plate being mounted rotatably movable about the rotation axis of the propeller, the inner plate and the outer plate being separated from each other by an antifriction bearing such that the inner plate and the outer plate are independent in terms of rotation about the rotation axis and tilt integrally relative to the orthogonal plane, wherein the cylinder is actuated to change the tilt of the inner plate, and the hinge system hinges the outer plate to the blade;

[0030] - The system further includes balls, the balls including a domed outer surface, the plate assembly including an inner surface having a shape complementary to the outer surface of the balls and being positioned in contact with the outer surface of the balls such that the outer surface of the balls guides an inclined displacement of the plate assembly;

[0031] - The articulated system includes a set of connecting rods, each connecting rod being articulated at a first end to an associated blade by a pivot joint and at a second end to the plate assembly, the connecting rods being mounted to move rotatably about the axis of rotation of the propeller such that an inclination of the plate assembly causes a corresponding displacement of the connecting rods, the corresponding displacement of the connecting rods being capable of periodically changing the pitch of the blades;

[0032] - The system further includes a control unit adapted to generate a control signal for the pitch of the blades based on a comparison between a measurement signal from a force sensor and a predetermined setpoint signal, the control signal being adapted to actuate the cylinder when the measurement signal differs from the setpoint signal Scons by a predetermined difference over a predetermined time period;

[0033] - The system further includes a system for controlling the total pitch of the blades, the system for controlling the total pitch of the blades being configured to translate the plate assembly in a longitudinal direction while maintaining the same inclination of the plate assembly to identically change the pitch of each of the blades, the total pitch of the blades being independent of the cyclic pitch of the blades;

[0034] According to a second aspect, the invention relates to a turbine including a system for controlling the cyclic pitch of the blades of a propeller according to the first aspect.

[0035] According to a third aspect, the invention relates to an aircraft including a system for controlling the cyclic pitch of the blades of a turbine propeller according to the first aspect. Description of the Drawings

[0036] Other features, objects, and advantages of the present invention will become apparent upon reading the following detailed description, given by way of non-limiting example, which will be illustrated by the following drawings:

[0037] Already described Figure 1a Shows a schematic view of an aircraft during a steady flight phase, the air flow at the inlet of the blades of the propeller having a longitudinal component.

[0038] Already described Figure 1b Shows a schematic view of an aircraft during a climb phase, the air flow at the inlet of the blades of the propeller having a longitudinal component and a lateral component.

[0039] Already described Figure 2a and Figure 2bSchematic diagrams of the propellers of an open rotor engine and a shrouded turbofan engine are respectively shown.

[0040] Figure 3a A schematic perspective view of a bearing support portion of a system for controlling the cyclic pitch of blades according to an embodiment of the present invention is shown.

[0041] Figure 3b and Figure 3c Schematic partial perspective views and a schematic front view of a system for controlling the cyclic pitch of blades according to an embodiment of the present invention are respectively shown.

[0042] Figure 4a and Figure 4b Schematic side views and a schematic front view of a system for controlling the cyclic pitch of blades according to an embodiment of the present invention are respectively shown, wherein the plate assembly is not inclined.

[0043] Figure 5a and Figure 5b Schematic side views and a schematic front view of a system for controlling the cyclic pitch of blades according to an embodiment of the present invention are respectively shown, wherein the plate assembly is inclined.

[0044] Figure 5c Shows the schematic diagram of the periodic change of the pitch of the blades of the components shown in Figure 5a and Figure 5b during a complete rotation of the propeller.

[0045] Figure 6 and Figure 7 Schematic side views of the first orientation and the second orientation of an engine of a system for controlling the cyclic pitch of blades according to an embodiment of the present invention are respectively shown.

[0046] Figure 8 A schematic diagram showing the representation of forces in an orthogonal plane for a system according to an embodiment of the present invention, the system being for controlling the cyclic pitch of blades and including two cylinders or three cylinders.

[0047] Figure 9 A schematic diagram of a cylinder and a plate portion of a system for controlling the cyclic pitch of blades according to an embodiment of the present invention is shown.

[0048] Figure 10 A schematic diagram of the generation of a control signal of a system for controlling the cyclic pitch of blades according to an embodiment of the present invention is shown. Detailed Description

[0049] Preliminary concept

[0050] In the present application, the term propeller is used, for example, to refer to the fan propeller of a turbofan engine, the propeller of a turboprop engine, or even the propeller of an open rotor engine.

[0051] The axis of rotation of the propeller is referred to as the longitudinal axis r. The stator reference system is the reference system in which the blades 1 of the propeller rotate during the operation of the turbine. The rotor reference system is the reference system in which the blades 1 of the propeller are fixed during the operation of the turbine.

[0052] The terms internal and external are defined such that the internal part or internal face of an element is closer to the longitudinal axis r than the external part or external face of the same element.

[0053] General introduction of the system for controlling the periodic pitch of blade 1

[0054] The system for controlling the cyclic pitch of the blades 1 of a turbine is illustrated by way of example in FIGS. 3 to Figure 7 The system includes a set of blades 1 that can move rotationally about the axis of rotation r relative to the stator reference system of the turbine. The blades 1 are arranged in a plane P (referred to as the orthogonal plane P) that is orthogonal to the axis of rotation r of the propeller. The system is characterized in that it includes:

[0055] - a plate assembly 40 that can be tilted relative to the orthogonal plane P,

[0056] - a hinge system 50 that hinges the plate assembly 40 relative to the blades 1 such that tilting of the plate assembly 40 causes a periodic change in the pitch of the blades 1,

[0057] And the system includes:

[0058] - a force sensor 5 that is mounted fixed in the stator reference system. The force sensor 5 is adapted to measure the force exerted in the orthogonal plane P by the air flow at the inlet of the blades 1 of the propeller,

[0059] - a cylinder 60 that is adapted to tilt the plate assembly 40. The cylinder 60 is adapted to be actuated in response to the force measured by the force sensor 5.

[0060] The system for controlling the cyclic pitch of the blades can be applied to turbines having a shrouded architecture (such as a turbofan engine with a high bypass ratio) or turbines having an unshrouded architecture (such as an open rotor engine or a turboprop engine).

[0061] The force sensor 5 enables the measurement of the force exerted by an air flow in the orthogonal plane P, which has an angle of attack with respect to the rotation axis r of the blade 1 and which includes a longitudinal component and an orthogonal component with respect to the rotation axis r.

[0062] The force sensor 5 can continuously measure the force during the operation of the propeller. Thus, the force is measured in real time during flight, independently of any prior knowledge of the blade 1 or of any prior knowledge of the flight characteristics of the aircraft. Thus, the system enables the pitch of the blade 1 to be adjusted in real time as a function of the variation in the measured value of the force during flight, regardless of the type of predictable or unpredictable phase. Furthermore, the adjustment of the pitch of the blade is made as a function of the measured value of the force and thus does not require data based on the aircraft, such as the trim of the aircraft or the attitude of the aircraft. Thus, the system meets regulatory standards, the safety of the system is increased and it is independent of aircraft data, and the system does not interfere with the flyability of the aircraft.

[0063] The system for controlling the cyclic pitch of the blade 1 enables a specific pitch to be applied to each blade 1 by tilting the plate assembly 40. During the rotation of the blade 1, the pitch of the blade 1 varies periodically according to a curve, which may be of the sine type (illustrated by the example in Figure 5c . Figure 5b An example of a configuration is shown in which the pitch of the blade is periodic. The more the plate assembly 40 is tilted, the greater the amplitude of the variation in the pitch of the blade 1 during the rotation of the blade. Thus, the control system enables a cyclic pitch to be applied to the blade 1.

[0064] The cylinder 60 of the system for controlling the cyclic pitch of the blade 1 is actuated in response to the measured force, which enables the pitch of the blade 1 to be adjusted by tilting the plate assembly 40 as a function of the force applied in the orthogonal plane P. In particular, the pitch of the blade 1 can be adjusted to balance the force exerted on the blade 1 by the air flow in order to achieve a longitudinal thrust and to reduce or even eliminate the disturbing force applied in the orthogonal plane P.

[0065] In particular, an air flow that is not oriented only in the longitudinal direction (i.e., an air flow that includes a longitudinal component oriented along the rotation axis r and an orthogonal component oriented in the orthogonal plane P) may generate a force on the blade 1 in the orthogonal plane P.

[0066] That is, when the air flow has an angle of attack with respect to the orthogonal plane P, the system for controlling the cyclic pitch of the blade makes it possible to reduce or even eliminate the forces exerted on blade 1 in the orthogonal plane P due to the non-uniform distribution of the air flow. This makes it possible to ensure symmetric drag and symmetric thrust on blade 1 of the propeller. Therefore, the aerodynamic moment (1P moment) generated on blade 1 of the propeller by the non-uniform air flow can be reduced or even eliminated in real time and permanently. In other words, the system makes it possible to align the thrust of the propeller with the longitudinal axis r of the turbine by eliminating the disturbing forces and moments in the orthogonal plane P at the axis of rotation of blade 1 of the propeller.

[0067] By reducing or eliminating the 1P moment supported by blade 1 of the turbine during flight, the system for controlling the cyclic pitch of blade 1 makes it possible to reduce the mass of the structure that bears the 1P moment (such as blade 1 or even the components providing the attachment of the propeller to the aircraft), and thus also reduce the loads caused by this mass. The system also makes it possible to reduce the wear of blade 1 and the wear of the components providing the attachment of the propeller to the aircraft, and also reduces the number and cost of related maintenance operations.

[0068] Structure of the turbine

[0069] The turbine may include an intermediate housing fixed in the stator reference system of the turbine, and the intermediate housing is not driven to rotate about the axis of rotation r of the propeller having blade 1.

[0070] The intermediate housing of the turbine may include a bearing support 20. Thus, the bearing support 20 is a component fixed in the stator reference system.

[0071] In the case of a turbofan engine having a fan, the intermediate housing may have a part of the fan housing and a part of the low-pressure compressor. The system for adjusting the pitch of blade 1 is generally located at the fan housing.

[0072] The turbine may include a rotor shaft 10, and the rotor shaft is rotationally coupled to blade 1 of the propeller. The rotor shaft 10 may be articulated relative to the bearing support 20 by one or more antifriction bearings 15, 16. Thus, the rotor shaft 10 is driven to rotate about the longitudinal axis r during the operation of the propeller, while the bearing support 20 is not driven to rotate about the longitudinal axis r during the operation of the propeller, and the bearing support 20 is fixed in the stator reference system.

[0073] The rotor shaft 10 may have an inner portion 11, an outer portion 12, and a connecting portion 13 that connects the inner portion 11 and the outer portion 12. The inner portion 11 and the outer portion 12 of the rotor shaft 10 are substantially cylindrical about the rotational axis r of the propeller. The outer portion 12 is arranged at a position more external relative to the rotational axis r than the inner portion 11.

[0074] The outer portion 12 rotates integrally with the blade 1 of the propeller and is rotatably movable relative to the intermediate housing by one or more antifriction bearings 15. The inner portion 11 is rotatably movable relative to the intermediate housing by one or more antifriction bearings 16. The inner portion 11 of the rotor shaft 10 may be rotatably coupled to the shaft of the low-pressure turbine 18 by a reduction gear.

[0075] The bearing support 20 may be an annular support disposed between the inner portion 11 and the outer portion 12 of the rotor shaft 10. During operation of the propeller, the bearing support 20 may be centered about the rotational axis r and rotatably movable about the rotational axis r.

[0076] The bearing support 20 may have a substantially cylindrical portion 21 disposed about the inner portion 11 of the rotor shaft 10, and a frustoconical portion 22 that is coupled to the substantially cylindrical portion 21 on one hand and, for example, to the intermediate housing at the low-pressure compressor on the other hand.

[0077] Force sensor 5

[0078] The force sensor 5 may be a strain gauge. The strain gauge has good reliability under extreme operating conditions, can be integrated into a constrained environment, and has a satisfactory service life.

[0079] As a variant, for a shrouded architecture, the force sensor 5 may be a proximity sensor that is disposed on the shroud and measures the deformation of the blade 1. As a variant, the force sensor 5 may be a pressure sensor that measures the aerodynamic pressure field near the sensor.

[0080] The force sensor 5 is mounted to be fixed in the stator reference frame, i.e., the force sensor 5 is not driven to rotate during operation of the propeller. Thus, the installation of the force sensor 5 becomes easy, the number and arrangement of the force sensors 5 are less constrained, and the force sensor improves the reliability of the measurement relative to, for example, sensors that would be directly mounted on the blade 1 or other rotating components.

[0081] The force sensor 5 can in particular be mounted on a fixed part in the stator reference system and measure the force applied to this part in the orthogonal plane P. When the air flow includes a longitudinal component and a component perpendicular to the longitudinal direction, this type of force represents the force applied by the air flow at the inlet of the blade 1 of the propeller in the orthogonal plane P.

[0082] The force sensor 5 can be adapted to be positioned at the bearing support 20 of the intermediate housing of the turbine. In particular, the force sensor 5 can be arranged at the frustoconical part 22 of the bearing support 20.

[0083] During the rotation of the propeller, the force applied to the blade 1 of the propeller is transmitted to the bearing support 20 through one or more antifriction bearings 16, which are arranged between the rotor shaft 10 and the bearing support 20, for example, between the inner part 11 of the rotor shaft 10 and the bearing support 20. Therefore, the force measured on the bearing support 20 represents the force applied to the blade 1 of the propeller. One or more bearings 16 transmit the bending to the intermediate housing, which can be captured by the force sensor 5 and converted into a lateral load on the propeller. By way of non-limiting example, Figure 6 and Figure 7 two antifriction bearings 16 are shown, one antifriction bearing being near the plate assembly 40 and the other antifriction bearing being near the frustoconical part 22 of the bearing support 20.

[0084] When the thrust is not oriented only in the longitudinal direction, the force generated on the blade 1 (and thus on the bearing support 20) is non-uniform over the entire circumference of the bearing support 20, which causes deformation of the bearing support 20. The force sensor 5 measures the deformation of the bearing support 20, which represents the force applied to the blade 1 of the propeller. In particular, the deformation of the bearing support 20 can be a bending deformation, which is oriented in a direction corresponding to the direction of the disturbing force applied to the blade 1 in the orthogonal plane P.

[0085] The force sensor 5 can be glued to the face of the bearing support 20. As a variant, a hollow part can be arranged in the bearing support 20 and the force sensor 5 can be embedded in this hollow part. As a variant, the force sensor 5 can be welded to the bearing support 20 or fixed to the bearing support 20 by any conceivable means.

[0086] The force sensor 5 can measure the deformation of the bearing support 20 in the measurement direction, which represents the disturbing force applied to the blade 1 in the measurement direction.

[0087] The force sensor 5 can be calibrated to establish a function that relates the force measured in the measurement direction to the electrical measurement signal emitted by the force sensor 5. For this calibration, the bearing support 20 is loaded in the measurement direction of the force sensor 5, for example, by a cylinder 60 or a mass body. For a determined value of the force in the measurement direction, the force sensor 5 is powered to obtain a desired voltage change at the output of the sensor. The calibration can be repeated for multiple values of the force in the measurement direction.

[0088] The calibration enables the acquisition of a force function that relates the force in the measurement direction to the output voltage of the force sensor 5 (i.e., the measurement signal Sm). Then, the force E applied to the bearing support 20 can be related to the voltage V at the output of the force sensor 5 through the force function f according to the following relationship: E = f(V).

[0089] The system for controlling the cyclic pitch of the blade 1 may include one or more force sensors 5 arranged in one or more sets of force sensors 501, 502. A system including multiple force sensors 5 provides better measurement accuracy, reduces possible inaccuracies, errors, or measurement deviations, and corrects interference phenomena different from the phenomenon to be observed.

[0090] Each set of one or more force sensors 501, 502 can measure the deformation of the bearing support 20 in the measurement direction with respect to the orthogonal plane P of the axis of the propeller, and this deformation represents the component of the disturbing force applied to the blade 1 in the measurement direction.

[0091] If the system includes multiple sets of force sensors 501, 502 with different measurement directions, the calibration can be repeated for each measurement direction.

[0092] By way of example, the system for controlling the cyclic pitch of the blade 1 may include two sets of force sensors 501, 502, and each set of force sensors includes one or more force sensors 5. The first set of force sensors 501 is adapted to measure the force in the first direction of the orthogonal plane P, and the second set of force sensors 502 is adapted to measure the force in the second direction of the orthogonal plane P.

[0093] The second direction may be perpendicular to the first direction. As a variant, the second direction may be a direction different from the first direction and not perpendicular to the first direction.

[0094] The system may further include a first cylinder 60 and a second cylinder 60. The first cylinder is adapted to be actuated in response to the force measured by the first set of force sensors 501, and the second cylinder is adapted to be actuated in response to the force measured by the second set of force sensors 502.

[0095] Thus, regardless of the forces applied in the orthogonal plane P at the rotational axis r of the propeller, the two sets of force sensors 501, 502 measure the forces applied to the bearing support 20 in two measurement directions. These forces represent the forces applied to the blade 1 of the propeller in the orthogonal plane P, and the arrangement of the set of force sensors 501, 502 enables the pitch of the blade 1 of the propeller to be adjusted by two cylinders 60 in response to the forces measured in the orthogonal plane P.

[0096] Figure 3a An exemplary embodiment is shown in which the system for pitching the blade 1 includes two sets of force sensors 501, 502. Each set of the two sets of force sensors 501, 502 includes strain gauges that are arranged to form a Wheatstone bridge of four unidirectional variable resistors. The four strain gauges are arranged in pairs on the bearing support 20 in two pairs that are radially opposite to each other in the measurement direction. The four strain gauges 501 are arranged in pairs at 6 o'clock and 12 o'clock and capture vertical bending. The four strain gauges 502 are arranged in pairs at 3 o'clock and 9 o'clock and capture horizontal bending. Each pair of strain gauges includes a first strain gauge that captures bending and is arranged in the axial direction, and the two pairs of strain gauges of a set enable errors or deviations to be excluded in axial bending. Each pair of strain gauges includes a second strain gauge that is arranged perpendicular to the first strain gauge, which enables torsion and housing expansion associated with thermal effects to be excluded. This type of arrangement of the force sensor 5 in the form of a Wheatstone bridge enables measurement deviations caused by, for example, the environmental conditions in which the force sensor 5 is located, such as deviations caused by torsion and temperature, to be eliminated. The strain gauge bridge enables torques and / or axial forces measured on some of the sensors in the sensor 5 rather than on others to be excluded to eliminate inaccuracies, errors, or measurement deviations, and to correct interference phenomena that are different from the phenomena to be observed.

[0097] Figure 3c An exemplary embodiment is shown in which the system for pitching the blade 1 includes two force sensors 5 in three sets, which are arranged on the bearing support 20 at 120° from each other. Each set of force sensors measures the force in the measurement direction, and one set of force sensors 5 is used to determine the vertical force and the horizontal force. This type of arrangement of the force sensor 5 enables the functions of the force sensors to be shared, and thus fewer force sensors 5 can be used.

[0098] The system may also include additional strain gauges to improve the exclusion of interference phenomena, for example, to improve the exclusion of temperature measurement deviations. In addition, the groups of force sensors may be redundant or even separate to improve the reliability of the measurement.

[0099] Plate component 40

[0100] In Figure 6 and Figure 7 the plate assembly 40 shown by way of non - limiting example can be inclined relative to the orthogonal plane P at the rotational axis r of the propeller. In other words, the plate assembly 40 can be displaced to form a non - zero angle with the plane formed by the blades 1 of the propeller. The change in the inclination of the plate assembly 40 causes a change in the pitch of the blades 1 via the hinge system 50.

[0101] The plate assembly 40 can be annular and have axial symmetry about the rotational axis r. Thus, the inclination of the plate assembly 40 relative to the orthogonal plane P causes two diametrically opposite points of the plate assembly 40 to be displaced in opposite directions by the same magnitude.

[0102] The plate assembly 40 can include an inner plate portion 41 and an outer plate portion 42. The inner plate portion 41 and the outer plate portion 42 are independent in terms of rotation about the rotational axis r of the propeller and are inclined integrally relative to the orthogonal plane P.

[0103] The inner plate portion 41 and the outer plate portion 42 can be annular and centered on the rotational axis r of the propeller. The outer plate portion 42 is located farther from the rotational axis r of the propeller than the inner plate portion 41.

[0104] The inner plate portion 41 is mounted to be fixed in the stator reference frame, i.e., the inner plate portion is not driven to rotate about the rotational axis r of the propeller. The outer plate portion 42 is mounted to be rotatably movable about the rotational axis r of the propeller and is driven to rotate about the rotational axis r of the propeller during the operation of the propeller, and the outer plate portion 42 follows the rotation of the blades 1.

[0105] The inner plate portion 41 and the outer plate portion 42 can be separated from each other by bearings 43 such that the inner plate portion 41 and the outer plate portion 42 are independent in terms of rotation about the rotational axis r and are inclined integrally relative to the orthogonal plane P. The bearings 43 can be arranged between the inner plate portion 41 and the outer plate portion 42, particularly at the cutouts formed in each of the inner annular plate portion 41 and the outer annular plate portion 42. The bearings 43 are antifriction bearings and can be double - ball bearings with opposing angular contacts. Due to the antifriction bearings 43, when the outer plate portion 42 is driven to rotate about the rotational axis r of the propeller during the operation of the propeller, the inner plate portion 41 is not driven to rotate about the rotational axis r of the propeller and remains fixed in the stator reference frame. On the other hand, the inclination of the inner plate portion 41 relative to the orthogonal plane P drives a corresponding inclination of the outer plate portion 42 relative to the orthogonal plane P.

[0106] When the plate assembly 40 is not tilted, the inner plate portion 41 may have a generally cylindrical shape about the rotation axis r. Thus, for a zero tilt of the plate assembly 40, the stroke of the cylinder 60, which is arranged generally in the longitudinal direction between the frustoconical portion 22 of the bearing support 20 and the inner plate portion 41, is substantially the same regardless of the position of the cylinder 60 about the rotation axis r.

[0107] When the plate assembly 40 is not tilted, the outer plate portion 42 may have a generally cylindrical shape about the rotation axis r and a generally circular outer periphery about the rotation axis r. Thus, for a zero tilt of the plate assembly 40, the distance between the plate assembly 40 and the blade 1 is the same.

[0108] The bearing support 20 of the intermediate housing may be located between the inner portion 11 of the rotor shaft 10 and the inner plate portion 41 of the plate assembly 40.

[0109] The rotor shaft 10 may be articulated, for example, at the outer portion 12 of the rotor shaft to the outer plate portion 42 by means of a rotary compass element 14 and relative to the articulation system 50 at the junction with the blade 1 by means of one or more antifriction bearings 17.

[0110] During operation of the propeller, the bearing support 20 with the force sensor 5 mounted thereon and the inner plate portion 41 are not driven to rotate about the rotation axis r of the propeller. On the other hand, the rotor shaft 10, the outer plate portion 42, the articulation system 50 and the blade 1 are driven to rotate about the rotation axis r, and these components rotate integrally.

[0111] The cylinder 60 may be actuated to change the tilt of the inner plate portion 41, and the articulation system 50 may articulate the outer plate portion 42 relative to the blade 1. Thus, actuation of the cylinder 60 in response to the force measured by the force sensor 5 results in a change in the tilt of the inner plate portion 41, which causes a corresponding change in the tilt of the outer plate portion 42. The inner plate portion 41 and the outer plate portion 42 tilt integrally, which causes a change in the pitch of the blade 1.

[0112] The system may also include balls 30. The balls 30 may be annular about the rotation axis r and include an outer surface 31. The annular balls 30 may be arranged between the rotor shaft 10 and the plate assembly 40, more precisely, between the bearing support 20 and the inner plate portion 41.

[0113] The plate assembly 40 (in particular, the inner plate portion 41) may include an inner surface 411 having a shape complementary to the outer surface 31 of the balls 30 and being positioned in contact with the balls 30 such that the outer surface 31 of the balls 30 guides the tilting displacement of the plate assembly 40.

[0114] The inner surface 411 of the inner plate portion 41 may have a shape complementary to the outer surface 31 of the ball 30 and is positioned to contact the outer surface 31 of the ball 30.

[0115] In particular, the ball 30 may have a domed outer surface 31. Thus, actuation of the cylinder 60 causes an inclined displacement of the plate assembly 40 by sliding of the plate assembly 40 in contact with the domed outer surface 31 of the ball 30. A more or less domed shape of the outer surface 31 of the ball 30 may cause the plate assembly 40 to incline more or less for the same displacement of the cylinder 60, and thus may cause the pitch of the blade 1 to change more or less for a given displacement of the cylinder 60.

[0116] As a variant, the outer surface 31 of the ball 30 may have any suitable shape to guide the inclined displacement of the plate assembly 40 during actuation of the plate assembly 40 by the cylinder 60.

[0117] Figure 3b A partial 3D view of the inner portion 11 of the rotor shaft 10, the bearing support 20, the ball 30, the inner plate portion 41, and the cylinder 60 according to an exemplary embodiment is shown. The antifriction bearing 43 between the inner plate portion 41 and the outer plate portion 42 and the system 50 for hinging the plate assembly 40 relative to the blade 1 are not shown.

[0118] Hinge system 50

[0119] In Figure 4a , Figure 5a , Figure 6 and Figure 7 The hinging system 50 shown by way of non-limiting example in may include a set of connecting rods 51. Each connecting rod 51 may be hinged to the associated blade 1 at a first end 511 and to the plate assembly 40 at a second end 512. The connecting rods 51 may be mounted to move rotatably about the rotational axis r of the propeller. The displacement of the connecting rods 51 may cause the rotation of the blade 1, and the rotation of the blade can change the pitch of the blade. Thus, the inclination of the plate assembly 40 causes a corresponding displacement of the connecting rods 51, and the corresponding displacement of the connecting rods can periodically change the pitch of the blade 1. In particular, each connecting rod 51 may be connected to the blade 1 by a pivot joint 513.

[0120] In other words, whether the connecting rod 51 is pulled or pushed by the plate assembly 40, the connecting rod 51 may be displaced to cause the blade 1 to rotate about the pivot. When the blade 1 rotates about the pivot, the pitch of the blade thus changes, the pitch of the blade being the angle formed between the axis connecting the leading edge and the trailing edge of the blade 1 on the one hand and the rotational axis r of the propeller on the other hand.

[0121] Thus, the movement of the tilt adjustment link rod 51 of the plate assembly 40. When the plate assembly 40 is not tilted, the link rod 51 can be arranged substantially in the longitudinal direction. When the plate assembly 40 is tilted, each link rod 51 has a position different from that of the other link rod 51, and thus is periodically displaced during the rotation of the propeller, which thus causes a periodic change in the pitch of the blade 1.

[0122] In particular, each link rod 51 can be connected to the outer plate portion 42 at the second end portion 512 of the link rod. Thus, the tilt of the plate assembly 40, and thus the tilt of the outer plate portion 42, causes a periodic displacement of the second end portion 512 of the link rod 51, and thus causes a periodic displacement of the first end portion 511 of the link rod 51. The periodic displacement of the first end portion 511 of the link rod 51 can periodically change the pitch of the blade 1.

[0123] More precisely, the link rods 51 can be distributed on the substantially circular outer peripheral edge of the outer plate portion 42, and the arrangement of the link rods 51 corresponds to the arrangement of the blades 1. Thus, when the plate assembly 40 is not tilted, the first end portions of the link rods 51 are arranged substantially in a circle in a plane P orthogonal to the rotation axis r of the propeller.

[0124] The tilt of the outer plate portion 42 relative to the orthogonal plane P causes a corresponding tilt of the substantially circular outer peripheral edge of the outer plate portion 42, and thus causes a corresponding tilt of the circle formed by the first end portions 511 of the link rods 51, which causes the first end portions 511 of two radially opposite link rods 51 to be displaced in opposite directions with the same amplitude on the outer peripheral edge of the outer plate portion 42. Thus, the two blades 1 associated with the two radially opposite link rods 51 experience opposite changes in the pitch of the two blades with the same amplitude. Thus, the blades 1 of the system have a periodic and continuously variable pitch during the rotation of the blades 1.

[0125] Cylinder 60

[0126] The system includes a cylinder 60 adapted to tilt the plate assembly 40, and the cylinder 60 is actuated in response to the force measured by the force sensor 5. The cylinder 60 is shown by way of non-limiting example in Figure 3b 、 Figure 3c and Figures 6 to 9 .

[0127] The actuation of the cylinder 60 can change the tilt degree of the plate assembly 40, thereby changing the pitch of the blade 1.

[0128] The cylinder 60 can include a rod that can be retracted or extended by a cylinder actuator 60, thereby changing the stroke of the cylinder 60.

[0129] The cylinder 60 can be arranged substantially in the longitudinal direction r. The cylinder 60 can have a first end 61 connected to the bearing support 20 and a second end 62 connected to the plate assembly 40. In particular, the second end 62 of the cylinder 60 can be mounted on the inner plate portion 41 at the outer peripheral edge of the inner plate portion 41, and the first end 61 of the cylinder 60 can be mounted on the frustoconical portion 22 of the bearing support 20 at a position in the orthogonal plane P, and the position of the first end of the cylinder in the orthogonal plane is substantially the same as the position of the second end 62 of the cylinder 60 in the orthogonal plane P. Thus, the cylinder 60 is arranged substantially in the longitudinal direction between the bearing support 20 and the inner plate portion 41.

[0130] The cylinder 60 is actuated to translate along the longitudinal axis r. The displacement of the cylinder 60 in the longitudinal direction causes a corresponding displacement of the portion of the plate assembly 40 on which the cylinder 60 is mounted. This displacement causes the plate assembly 40 to tilt in a direction perpendicular to the longitudinal axis r, and if necessary, the tilt of the plate assembly 40 is guided by the balls 30.

[0131] Therefore, the displacement of the cylinder 60 causes a change in the tilt angle of the inner plate portion 41, which in turn causes a change in the tilt angle of the outer plate portion 42, which causes a displacement of the connecting rod 51 of the pitch of the blade 1, and the displacement of the connecting rod of the pitch of the blade 1 can change the pitch of the blade 1.

[0132] The system for controlling the cyclic pitch of the blade 1 can include a plurality of cylinders 60 adapted to be displaced by one or more actuators.

[0133] By way of example, the system for pitching the blade 1 can include two cylinders 60, which are arranged around the outer peripheral edge of the inner plate portion 41 and are spaced apart from each other at an angular pitch of 90°. In Figure 9 this configuration is illustrated by way of example. Thus, the actuation of the first cylinder 60 enables the inner plate portion 41 to tilt in a first direction, and the actuation of the second cylinder 60 enables the inner plate portion 41 to tilt in a second direction, which is perpendicular to the first direction.

[0134] The actuation of the first cylinder 60, i.e., the retraction or extension of the rod of the first cylinder 60, can be done independently of the actuation of the second cylinder 60. Thus, the tilt of the plate assembly 40 in the first direction and the tilt in the second direction can be controlled independently, and any combination of the tilt of the plate assembly 40 in the first direction and the tilt in the second direction can be envisaged.

[0135] In Figure 7It is shown by way of non-limiting example that the system may also include an anti-rotation connecting rod 65. The anti-rotation connecting rod 65 may have a first end and a second end 62, the first end being mounted on the bearing support 20, particularly at the generally cylindrical portion 21 of the bearing support 20, and the second end being mounted on the plate assembly 40, particularly on the inner plate portion 41. The anti-rotation connecting rod 65 prevents the inner ring of the bearing 43 from rotating, thereby preventing the cylinder 60 from twisting.

[0136] Control rules

[0137] The actuation of the cylinder 60 is controlled in response to the force measured by the force sensor 5, and the actuation of the cylinder 60 causes a periodic change in the pitch of the blade 1 through the tilting of the plate assembly 40. In Figure 10 A schematic diagram showing an example of a control rule for actuating the cylinder 60 is shown.

[0138] To this end, the system for controlling the periodic pitch of the blade 1 may include a control unit 70, which is adapted to generate a control signal Scom for the pitch of the blade 1 based on a comparison between a measurement signal Sm from the force sensor 5 and a predetermined setpoint signal Scons, and the cylinder 60 is adapted to shift in response to the control signal Scom.

[0139] For example, in the case where the force sensor 5 is a strain gauge, the measurement signal Sm from the force sensor 5 may correspond to the output voltage of the force sensor 5, and the measurement signal Sm depends on the force applied to the force sensor 5 in the measurement direction.

[0140] The setpoint signal Scons has a predetermined value, which corresponds to the output measurement signal Sm of the force sensor 5 obtained when the force measured by the force sensor 5 in the measurement direction corresponds to a predetermined force in the measurement direction.

[0141] The comparison between the measurement signal Sm and the setpoint signal Scon can be performed in real time by the control unit 70 during flight. Thus, the periodic control of the pitch of the blade 1 is performed in a closed loop, that is, the system takes into account the influence of the movement of the cylinder 60 on the output measurement signal Sm of the force sensor 5 to control the shift of the cylinder 60.

[0142] When the measurement signal Sm corresponds to the setpoint signal Scons, the control unit 70 may generate a control signal Scom, which corresponds to the position of the cylinder 60 remaining unchanged and thus corresponds to the pitch of the blade 1 remaining unchanged.

[0143] On the other hand, when the measurement signal Sm is different from the setpoint signal Scons, the control unit 70 can generate a control signal Scom that corresponds to a change in the position of the cylinder 60 to change the pitch of the blade 1 such that the output measurement signal Sm of the force sensor 5 approaches the target setpoint signal Scons.

[0144] The value of the control signal Scom can vary according to the value of the difference between the measurement signal Sm and the setpoint signal Scons such that the magnitude of the change in the pitch of the blade 1 adapts to the difference between the measurement signal Sm and the setpoint signal Scons.

[0145] In Figure 10 The control loop illustrated by way of example in

[0146] can be implemented for each set of force sensors 5. For example, for a system having two sets of force sensors 5, the control unit 70 can control two control loops. For each loop, the control unit 70 generates a control signal Scom for pitching the blade 1 based on a comparison between the measurement signal Sm from the force sensor 5 associated with the loop and a predetermined setpoint signal Scons associated with the loop.

[0147] In a first embodiment, the cylinder 60 is located in the same plane as the force sensor 5. The system includes two sets of force sensors 5 and two cylinders 60. The two sets of force sensors respectively measure the horizontal force and the vertical force, and the two cylinders are respectively adapted such that actuation of the cylinders causes the plate assembly 40 to be displaced relative to the horizontal plane and relative to the vertical plane. The system includes two control loops, each control loop being associated with a cylinder 60. The control signal Scom generated for each loop controls the actuation of the associated cylinder 60. Figure 3a In a second embodiment, the cylinder 60 is located in a plane different from the plane of the force sensor 5. The system can include two sets of force sensors 5 (as illustrated by way of example in Figure 8 and three cylinders 60, as illustrated by way of example in

[0148] The three cylinders being evenly distributed on the periphery of the inner plate portion 41. In this case, the control unit 70 must perform calculations to control the cylinders 60.

[0149] Regardless of whether the system includes two cylinders or three cylinders 60, the plate assembly 40 can be equivalently tilted. In fact, the measured force can be inscribed in a configuration with three cylinders positioned at F1, F2, and F3 respectively, or in a configuration with two cylinders positioned at F2p and F3p respectively. Therefore, the stroke of the three cylinders 60 can be changed to control the pitch of the blade 1 in a manner equivalent to changing the cyclic pitch of the blade 1 in a system with two cylinders 60.

[0150] When the measured signal Sm differs from the setpoint signal Scons by a predetermined difference within a predetermined time period, the control unit 70 can be adapted to generate a control signal Scom suitable for actuating the cylinder 60, thereby changing the pitch of the blade 1.

[0151] As a variant, only consider the criterion of the predetermined difference between the measured signal Sm and the setpoint signal Scons to generate a control signal Scom suitable for actuating the cylinder 60 and thus changing the pitch of the blade 1.

[0152] The predetermined difference can be selected to keep the force on the blade 1 close to the desired setpoint force. In other words, when the force in the orthogonal plane P measured by the force sensor 5 exceeds a predetermined force within a predetermined time period, the control unit 70 can generate a control signal Scom corresponding to the actuation of the cylinder 60 and thus corresponding to the change in the pitch of the blade 1.

[0153] The predetermined force can be selected to optimize the operation of the propeller, minimize the loads on the engine suspension and the blade 1, reduce the mass of the propeller, and increase the service life of the propeller.

[0154] According to one embodiment, the actuation of the cylinder 60 is controlled to eliminate the disturbing force applied to the blade 1 in the plane P orthogonal to the rotational axis r of the blade 1. In this case, the setpoint signal Scons corresponds to the elimination of the force applied in the orthogonal plane P. In other words, the setpoint signal Scons corresponds to the measured signal Sm of the force sensor 5 that represents a force of zero in the measurement direction measured by the force sensor 5. The setpoint signal Scons can be equal to 0.

[0155] When the setpoint signal Sc corresponds to the elimination of the force in the orthogonal plane P, change the pitch of the blade 1 when a change in the direction of the thrust relative to the longitudinal thrust is detected.

[0156] A predetermined time period can be selected to ensure the stability of the system's response without excessive reactivity. For example, the predetermined time period can be between 0.1 second and 10 seconds, preferably between 0.5 second and 3 seconds, and preferably about 1 second. Thus, when the force sensor 5 measures a non-longitudinal force over a time period greater than one second, the control unit 70 generates a control signal Scom that tends to displace the cylinder 60 to eliminate the interfering non-longitudinal force, thereby achieving a zero measurement signal Sm of the output voltage from the force sensor 5.

[0157] Therefore, the system enables the control of the cyclic pitch of the blade so that the thrust vector of the propeller is aligned with the longitudinal axis r, which has the effect of reducing or even eliminating the 1P moment applied to the blade 1. Thereby reducing the mass of the propeller and increasing the service life of the propeller. In addition, the system responds to changes in the attitude of the aircraft while avoiding measurement deviations, and the system does not respond to faster phenomena such as gusts.

[0158] As a variant, the measurement signal Sm can be averaged over a given time period to disregard the value of the measurement signal Sm at the instant t but consider the average value of the measurement signal Sm over the given time period. Thus, the system does not respond to fast phenomena.

[0159] The control unit 70 can include a corrector of the PID (Proportional, Integral, Derivative) type.

[0160] The system can include two cylinders 60 that can be actuated to translate independently of each other along the longitudinal direction, and the two cylinders 60 are spaced apart at an angular pitch of 90°. The system can also include two sets of force sensors 5 that measure the forces applied in a first measurement direction and a second measurement direction, and the first measurement direction and the second measurement direction are perpendicular and lie in an orthogonal plane P. The forces applied in the orthogonal plane P include a first force component in the first measurement direction and a second force component in the second measurement direction, and the first force component is measured by the first force sensor 5 and the second force component is measured by the second force sensor 5.

[0161] The first cylinder 60 is arranged such that the actuation of the first cylinder causes the plate assembly 40 to tilt in a first direction, and the second cylinder 60 is arranged such that the actuation of the second cylinder causes the plate assembly 40 to tilt in a second direction.

[0162] When the first force sensor 5 measures a non-zero force, i.e., when the first force component is non-zero, the control unit 70 generates a control signal Scom which is determined to reduce the first force component by changing the stroke of the first cylinder 60, so as to tilt the plate component 40 in the first direction. Accordingly, the pitch of the blade 1 is changed in response to the non-zero force measured by the first force sensor 5. Similarly, when the second force sensor 5 measures a non-zero force, the control unit 70 generates a control signal Scom which is determined to displace the second cylinder 60 to change the pitch of the blade 1, thereby reducing the second force component.

[0163] The force sensor 5 may be associated with the cylinder 60 such that a displacement of the cylinder 60 in the longitudinal direction tilts the inner plate portion 41 in the measuring direction of the force sensor 5. As a variant, the number of cylinders 60 and force sensors 5 may be different, and / or the measuring direction may be offset with respect to the direction of tilt of the plate component 40 caused by the cylinder 60. In this case, the component of the force applied in the measuring direction projects onto the tilt direction of the plate component 40. Compared with the setpoint measurement signal Scon, the measurement signal Sm corresponds to the sum of the projections of the measurement signals of the force sensor 5 in the tilt direction of the plate component 40.

[0164] By way of example, in the Figure 9 illustrated, the first cylinder 60 enables the plate to tilt rotationally along the axis AB, thereby acting with a force FV, and the second cylinder 60 enables the plate to tilt rotationally along the axis CD, thereby acting with a force FH.

[0165] Accordingly, when measuring the force in the direction AB, the position of the second cylinder 60 is changed to tilt the plate component 40 in the direction CD, which tends to reduce the angle of attack of the blade 1 at point A, thereby resulting in a smaller thrust force on the side of point A of the blade 1, which causes a reduction in the force in the direction AB. Similarly, when measuring the force in the direction CD, then the first cylinder is displaced to tilt the plate component 40 in the direction AB, thereby reducing the force in the direction CD.

[0166] Total pitch system

[0167] The system for controlling the cyclic pitch of the blade 1 may further include a system for controlling the collective pitch of the blade 1, and the system for controlling the collective pitch of the blade is configured to change the pitch of all the blades 1 of the propeller simultaneously and identically.

[0168] The system for controlling the collective pitch of the blade 1 may be configured to displace the plate component 40 translationally in the longitudinal direction while maintaining the same tilt of the plate component 40, so as to change the pitch of each blade in the blades 1 identically. Figure 4b An example of a configuration is shown in which the pitch of all the blades is the same.

[0169] In particular, the system for controlling the collective pitch of the blade 1 can be configured to displace each connecting rod 51 in the connecting rod assembly identically, so as to change the pitch of each blade in the blade 1 identically.

[0170] The collective pitch of the blade 1 and the cyclic pitch of the blade 1 can be controlled independently of each other. The collective pitch of the blade 1 is independent of the cyclic pitch of the blade 1 and does not depend on the cyclic pitch. If the cyclic pitch of the blade changes the force applied to the blade 1, the cyclic pitch of the blade 1 can depend on the collective pitch.

[0171] The system for controlling the collective pitch of the blade 1 can include an actuator adapted to actuate the cylinder 60. The cylinder 60 can correspond to the cylinder 60 for changing the cyclic pitch of the blade 1, or to an additional cylinder 60 dedicated to the collective pitch of the blade 1. For a system including a plurality of cylinders 60, the strokes of all the cylinders 60 are changed simultaneously by the same value so that the plate assembly 40 is displaced translationally along the longitudinal axis r, and if applicable, the ball 30 is displaced translationally along the longitudinal axis. Accordingly, the pitches of all the blades 1 are changed simultaneously by the same value so that all the blades 1 are subjected to the same pitch. However, the inclination of the plate assembly 40 is not changed so that the blades 1 are not subjected to the cyclic pitch.

[0172] By way of example, the system for controlling the pitch of the blade 1 can include three cylinders 60, which are regularly distributed on the periphery of the inner plate portion 41 and are spaced apart from each other at an angular pitch of 120°. The system with three cylinders 60 can enable the plate assembly 40 to be inclined relative to the plane P in any inclination direction orthogonal to the rotation axis r of the propeller, and enable the plate assembly 40 to be displaced translationally along the longitudinal direction.

[0173] The collective pitch of the blade 1 is changed by the same translational displacement, that is, by the same change in the stroke of each of the three cylinders 60. This results in the translational displacement of the plate assembly 40 relative to the bearing support portion 20 along the longitudinal axis r without changing the inclination of the plate assembly, which results in the identical displacement of all the connecting rods 51 connected to the blade 1 at the first end 511 and to the plate assembly 40 at the second end 512. Accordingly, for all the blades 1, the pitch of the blade 1 is the same.

[0174] The cyclic pitch of the blade 1 is changed by different changes in the strokes of one or more of the three cylinders 60, which results in the inclination of the plate assembly 40 relative to the orthogonal plane P.

[0175] As in Figure 8It is shown by way of example that a system with three cylinders is equivalent to a system with two cylinders and further including a third cylinder dedicated to the collective pitch. In fact, the forces measured in the orthogonal planes, compensated by the three cylinders 60 positioned at F1, F2, and F3, can be inscribed in a configuration with two cylinders 60 positioned at F2p and F3p, and a third component is applied to the center of the blade assembly 40 at F1p to only change the collective pitch of the blade 1.

[0176] Other embodiments can be envisaged, and those skilled in the art can easily modify the embodiments or exemplary embodiments disclosed above, or envisage other embodiments within the scope of the present invention.

Claims

1. A system for controlling the pitch of blades (1) of a propeller of a turbine, the propeller comprising a set of blades (1) that are rotatably movable about a rotation axis (r) relative to a stator reference system of the turbine, the blades (1) being arranged in a plane orthogonal to the rotation axis (r) of the propeller, the plane being referred to as the orthogonal plane (P). The system is characterized in that the system comprises: - a plate assembly (40) that is tiltable relative to the orthogonal plane (P), - a hinge system (50) that hinges the plate assembly (40) relative to the blades (1) such that tilting of the plate assembly (40) causes a periodic change in the pitch of the blades (1). And the system comprises: - a force sensor (5) that is mounted fixed in the stator reference system, the force sensor (5) being adapted to measure the force exerted in the orthogonal plane (P) by an air flow at the inlet of the blades (1) of the propeller, and - a cylinder (60) that is adapted to tilt the plate assembly (40), the cylinder (60) being adapted to be actuated in response to the force measured by the force sensor (5). Wherein the plate assembly comprises an inner plate part (41) and an outer plate part (42), the inner plate part and the outer plate part being annular and centered on the rotation axis of the propeller, the outer plate part being positioned around the inner plate part and being located further from the rotation axis of the propeller than the inner plate part. Wherein the inner plate part (41) and the outer plate part (42) are separated from each other by an antifriction bearing (43) such that the inner plate part (41) and the outer plate part (42) are independent in terms of rotation about the rotation axis (r) and tilt integrally relative to the orthogonal plane (P), wherein the cylinder (60) is actuated to change the tilt of the inner plate part (41), and wherein the hinge system (50) hinges the outer plate part (42) relative to the blades (1).

2. The system for controlling the cyclic pitch of the blades (1) of the propeller of a turbine according to claim 1, wherein, The force sensor (5) comprises a strain gauge and is adapted to be positioned at a bearing support (20) of an intermediate housing of the turbine.

3. The system for controlling the pitch of blades (1) of a propeller of a turbine according to claim 1 or 2, the system comprising a first set of force sensors (501) and a second set of force sensors (502), the first set of force sensors being adapted to measure a force in a first direction of the orthogonal plane (P), the second set of force sensors being adapted to measure a force in a second direction of the orthogonal plane (P), the second direction being perpendicular to the first direction, the system further comprising a first cylinder and a second cylinder, the first cylinder being adapted to be actuated in response to the force measured by the first set of force sensors (501), the second cylinder being adapted to be actuated in response to the force measured by the second set of force sensors (502).

4. A system for controlling the pitch of a blade (1) of a propeller of a turbine according to claim 1 or 2, wherein, The inner plate part (41) is mounted and fixed in the stator reference system, and the outer plate part (42) is mounted to be rotatably movable about the rotation axis (r) of the propeller.

5. A system for controlling the cyclic pitch of a blade (1) of a propeller of a turbine according to claim 1 or 2, the system further comprising a ball (30) having a domed outer surface (31), wherein, The plate part assembly (40) includes an inner surface (411) having a shape complementary to the dome-shaped outer surface (31) of the ball (30) and positioned to contact the dome-shaped outer surface (31) of the ball (30), such that the dome-shaped outer surface (31) of the ball (30) guides the inclined displacement of the plate part assembly (40).

6. A system for controlling the cyclic pitch of the blades (1) of a propeller of a turbine, according to claim 1 or 2, wherein, The articulation system (50) includes a set of connecting rods (51), each connecting rod (51) being articulated at a first end (511) to an associated blade (1) by a pivot joint (513) and at a second end (512) to the plate part assembly (40). The connecting rods (51) are mounted to be rotatably movable about the rotation axis (r) of the propeller, such that the inclination of the plate part assembly (40) causes a corresponding displacement of the connecting rods (51), and the corresponding displacement of the connecting rods can periodically change the pitch of the blade (1).

7. A system for controlling the cyclic pitch of the blade (1) of a propeller of a turbine according to claim 1 or 2, the system further comprising a control unit (70) adapted to generate a control signal (Scom) for the pitch of the blade (1) based on a comparison between a measurement signal (Sm) from the force sensor (5) and a predetermined setpoint signal (Scons). When the measurement signal (Sm) differs from the setpoint signal (Scons) by a predetermined difference within a predetermined time period, the control signal (Scom) is adapted to actuate the cylinder (60).

8. A system for controlling the cyclic pitch of the blade (1) of a propeller of a turbine according to claim 1 or 2, the system further comprising a system for controlling the total pitch of the blade (1). The system for controlling the total pitch of the blade (1) is configured to translate the plate part assembly (40) in the longitudinal direction while maintaining the same inclination of the plate part assembly (40) to identically change the pitch of each of the blades (1). The total pitch of the blade (1) is independent of the cyclic pitch of the blade (1).

9. A turbine comprising a system for controlling the cyclic pitch of the blade (1) of a propeller of a turbine according to any one of claims 1 to 8.

10. An aircraft comprising a system for controlling the cyclic pitch of the blade (1) of a propeller of a turbine according to any one of claims 1 to 8.

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