The variable pitch propeller control system can have a source of adjustable, actuation hydraulic pressure, a feather valve openable to provide an actuation path of the actuation hydraulic pressure between the source and the actuator, and closeable to connect the actuator to a drain below the actuation hydraulic pressure and close the actuator path, and a bypass path parallel to the actuator path, the bypass path having a restricted flow area relative to a flow area of the actuator path.

The variable pitch propeller control system can have a source of adjustable, actuation hydraulic pressure, a feather valve openable to provide an actuation path of the actuation hydraulic pressure between the source and the actuator, and closeable to connect the actuator to a drain below the actuation hydraulic pressure and close the actuator path, and a bypass path parallel to the actuator path, the bypass path having a restricted flow area relative to a flow area of the actuator path.

A control system (50) for an electro-hydraulic servo-actuator (26) envisages: a controller (55), to generate a control current (I.sub.c), designed to control actuation of the electro-hydraulic servo-actuator (26), implementing a position control loop based on a position error (e.sub.p), the position error (e.sub.p) being a difference between a reference position (Pos.sub.ref) and a measured position (Pos.sub.meas) of the electro-hydraulic servo-actuator (26); and a limitation stage (58), coupled to the controller (55) to provide a limitation of the actuator speed of the electro-hydraulic servo-actuator (26); the limitation stage (58) limits a rate of change of a driving current (I.sub.d) to be supplied to the electro-hydraulic servo-actuator (26), in order to limit the actuator speed.

A control system (50) for an electro-hydraulic servo-actuator (26) envisages: a controller (55), to generate a control current (I.sub.c), designed to control actuation of the electro-hydraulic servo-actuator (26), implementing a position control loop based on a position error (e.sub.p), the position error (e.sub.p) being a difference between a reference position (Pos.sub.ref) and a measured position (Pos.sub.meas) of the electro-hydraulic servo-actuator (26); and a limitation stage (58), coupled to the controller (55) to provide a limitation of the actuator speed of the electro-hydraulic servo-actuator (26); the limitation stage (58) limits a rate of change of a driving current (I.sub.d) to be supplied to the electro-hydraulic servo-actuator (26), in order to limit the actuator speed.

A turbine engine including: a rotor having at least one variable-pitch blade which is guided to rotate on bearings relative to a fixed structure; a system for controlling the pitch of the at least one blade, the control system being rigidly secured to the rotor and including a first actuator driven by energy, and the control system further being disposed axially upstream of the bearings; a device for transferring the energy, which is disposed axially between the bearings, the transfer device including a stationary element and a mobile element; wherein the rotor is annular and delimits an inner space which is open towards the upstream side and inside of which the control system is disposed.

A turbine engine including: a rotor having at least one variable-pitch blade which is guided to rotate on bearings relative to a fixed structure; a system for controlling the pitch of the at least one blade, the control system being rigidly secured to the rotor and including a first actuator driven by energy, and the control system further being disposed axially upstream of the bearings; a device for transferring the energy, which is disposed axially between the bearings, the transfer device including a stationary element and a mobile element; wherein the rotor is annular and delimits an inner space which is open towards the upstream side and inside of which the control system is disposed.

The present disclosure describes a propeller control unit for controlling the blade pitch of a propeller. The unit includes an electrohydraulic servo valve (“EHSV”) and is connected to a propeller actuator that adjusts the blade pitch of a propeller. The EHSV operates to allow pressurized fluid to flow from a pressurized fluid source to the actuator to adjust the blade pitch of the propeller in a flight pitch range and a ground pitch range, to allow pressurized fluid to flow from the source to the actuator to adjust the blade pitch of the propeller in a flight pitch range but not a ground pitch range, and to block the flow of pressurized fluid from the source to the actuator and drain pressurized fluid from the actuator to prevent adjustment of the blade pitch of the propeller in the flight pitch range or the ground pitch range.

The present disclosure describes a propeller control unit for controlling the blade pitch of a propeller. The unit includes an electrohydraulic servo valve (“EHSV”) and is connected to a propeller actuator that adjusts the blade pitch of a propeller. The EHSV operates to allow pressurized fluid to flow from a pressurized fluid source to the actuator to adjust the blade pitch of the propeller in a flight pitch range and a ground pitch range, to allow pressurized fluid to flow from the source to the actuator to adjust the blade pitch of the propeller in a flight pitch range but not a ground pitch range, and to block the flow of pressurized fluid from the source to the actuator and drain pressurized fluid from the actuator to prevent adjustment of the blade pitch of the propeller in the flight pitch range or the ground pitch range.

An electric propulsion unit comprising a housing, an AC motor, a beta rod, a propeller, a governor, an inverter, and a controller. The AC motor is disposed within the housing and includes a plurality of bearings supported inside the housing, a hollow motor shaft rotatably coupled to the housing by the plurality of bearings, a stator which is supported by the housing, and a rotor which is mounted to the hollow motor shaft. The beta rod is axially translatable inside the hollow motor shaft. The propeller is mechanically coupled to the hollow motor shaft. The propeller includes propeller blades having an adjustable pitch angle which depends on an axial position of the beta rod. The governor is configured to adjust a pitch angle of the propeller blades by actuating axial translation of the beta rod. The inverter is disposed within the housing and connected to receive DC power for conversion into AC power. The controller is disposed inside the housing and configured to control operation of the inverter and control the pitch angle of the propeller blades.

A control system (50) for an electro-hydraulic servo-actuator (26) envisages: a controller (55), to generate a control current (I.sub.c), designed to control actuation of the electro-hydraulic servo-actuator (26), implementing a position control loop based on a position error (e.sub.p), the position error (e.sub.p) being a difference between a reference position (Pos.sub.ref) and a measured position (Pos.sub.meas) of the electro-hydraulic servo-actuator (26); and a limitation stage (58), coupled to the controller (55) to provide a limitation of the actuator speed of the electro-hydraulic servo-actuator (26); the limitation stage (58) limits a rate of change of a driving current (I.sub.d) to be supplied to the electro-hydraulic servo-actuator (26), in order to limit the actuator speed.