Electronically piloted low pitch stop protection

1 . A blade pitch control and protection system for a propeller comprising:

an actuator configured to be connectable to a propeller, such that displacement of said actuator corresponds to a change in blade pitch of said propeller;

an electronic unit;

a position control sensor configured to interact with said actuator, to detect actuator position and thereby said blade pitch of said propeller, and to send a control feedback signal to said electronic unit via a first channel, based on said blade pitch; and

a protection sensor configured to interact with said actuator to detect actuator position and thereby said blade pitch of said propeller, and to send a protection feedback signal to said electronic unit via a second channel, based on said blade pitch,

wherein said electronic unit is configured to, based on said control feedback signal received from the position sensor on the first channel, control movement of said actuator through a control command to alter said blade pitch, and

wherein said electronic unit is further configured to, based on said protection feedback signal received from the protection sensor on the second channel, control movement of said actuator through a protection command such that said blade pitch control command is overridden when said protection feedback signal indicates that the blade pitch has reached a predefined value,

a protection valve, in fluid communication with the actuator, wherein activation of the protection valve is configured to result in the actuation of blades of the propeller towards a coarse pitch,

wherein transmission via the first channel of the controller occurs to control propeller pitch in operation of the propeller below an overspeed threshold and via the second channel, which is segregated from the first channel, to activate the protection valve in operation of the propeller above the overspeed threshold.

2 . The system of claim 1 , wherein said predefined value is below a blade pitch value threshold, and the electronic unit is configured to, based on said protection feedback signal, control movement of said actuator through a protection command such that said blade pitch of said propeller is increased when said protection feedback signal indicates that the blade pitch has reached the predefined value.

3 . The system of claim 1 , wherein said control and protection sensors are configured to function mechanically and electrically independently of each other and have the capability to provide independent feedback signals via the first and second channels to the electronic unit.

4 . The system of claim 1 , wherein said control and protection sensors are simplex, duplex or triplex sensors.

5 . The system of claim 1 , wherein said first and second channels are single channel, dual channel or triple feedback signal channels.

6 . The system of claim 1 , the actuator comprise a transfer tube, wherein each of the control and protection sensors is connected to the transfer tube.

7 . The system of claim 6 , wherein each of the control and protection sensors are connected to the transfer tube through dedicated redundant mechanical kinematics.

8 . The system of claim 1 , wherein one, or both of said control and protection sensors comprises one or more rotational displacement sensors.

9 . The system of claim 8 , wherein said one or more rotational displacement sensors comprise an RVDT sensor.

10 . The system of claim 1 , wherein

one, or both of said control and protection sensors comprises one or more linear displacement sensor; or

wherein said one or more displacement sensors comprises an LVDT sensor.

11 . The system claim 1 , further comprising

a control device, said control device comprising:

an electro-hydraulic servovalve device;

at least one protection activation unit, configured to control movement of the protection valve;

wherein the electronic unit is configured to, based on said control feedback signal, command through a control command the electro-hydraulic servovalve device and thereby the movement of said actuator, and wherein, when said blade pitch has reached said predefined level, said electronic unit is configured to enable through a protection command said protection activation unit and thereby said protection valve and thereby isolate the actuator from the electro-hydraulic servovalve device, thereby overriding the control command.

12 . The system of claim 11 , wherein the protection valve is in fluid communication with the actuator, and wherein the electro-hydraulic servovalve device can be selectively set in fluid communication with the actuator through the protection valve.

13 . A propeller comprising:

at least one blade; and

a blade pitch control and protection system according to claim 1 .

14 . A method of controlling and protecting a blade pitch for a propeller comprising:

providing an actuator that is configured to be connectable to said propeller, such that displacement of said actuator corresponds to a change in blade pitch of said propeller;

providing an electronic unit,

providing a position control sensor to said actuator, said position control sensor being configured to interact with said actuator, to detect actuator position and thereby said blade pitch of said propeller, and said position control sensor sending a control feedback signal to said electronic unit via a first channel, based on said blade pitch, and

providing a protection sensor to said actuator, configured to interact with said actuator and to detect actuator position and thereby said blade pitch of said propellor, and said protection sensor sending a protection feedback signal to said electronic unit via a second channel, based on said blade pitch,

said electronic unit controlling through a control command, based on said control feedback signal, movement of said actuator to alter said blade pitch, and

said electronic unit controlling through a protection command, based on said protection feedback signal, movement of said actuator such that said blade pitch control command is overridden when said protection feedback signal indicates that the blade pitch has reached a predefined value;

providing a protection valve, in fluid communication with the actuator, wherein activation of the protection valve is configured to result in the actuation of blades of the propeller towards a coarse pitch,

wherein transmission via the first channel of the controller occurs to control propeller pitch in operation of the propeller below an overspeed threshold and via the second channel, which is segregated from the first channel, to activate the protection valve in operation of the propeller above the overspeed threshold.

15 . The method of claim 14 , further comprising

providing a control device, said control device comprising an electro-hydraulic servovalve device, a protection valve, and at least one protection activation unit; and

controlling, via said protection activation unit, movement of said protection valve,

the electronic unit commanding through a control command, based on said control feedback signal, movement of said electro-hydraulic servovalve device, and thereby the movement of said actuator, and

wherein, when said blade pitch has reached said predefined level, said electronic unit enables through a protection command said protection activation unit and thereby said protection activation valve, isolating the actuator from the electro-hydraulic servovalve device and thereby overriding the control command.

16 . A blade pitch control and protection system for a propeller comprising:

an actuator configured to be connectable to a propeller, such that displacement of said actuator corresponds to a change in blade pitch of said propeller;

an electronic unit;

a position control sensor configured to interact with said actuator, to detect actuator position and thereby said blade pitch of said propeller, and to send a control feedback signal to said electronic unit via a first channel, based on said blade pitch; and

a protection sensor configured to interact with said actuator to detect actuator position and thereby said blade pitch of said propeller, and to send a protection feedback signal to said electronic unit via a second channel, based on said blade pitch,

wherein said electronic unit is configured to, based on said control feedback signal received from the position sensor on the first channel, control movement of said actuator through a control command to alter said blade pitch, and

wherein said electronic unit is further configured to, based on said protection feedback signal received from the protection sensor on the second channel, control movement of said actuator through a protection command such that said blade pitch control command is overridden when said protection feedback signal indicates that the blade pitch has reached a predefined value,

wherein the actuator comprises a transfer tube, wherein each of the control and protection sensors is connected to the transfer tube; and

wherein each of the control and protection sensors are connected to the transfer tube through dedicated redundant mechanical kinematics.