Protection for a circuit for controlling the orientation of propeller blades of an aircraft engine
A hydraulic control circuit of a steering actuator having a first and a second chamber, for orienting the blades of an aircraft engine propeller, this circuit comprising a high-pressure line and a low-pressure line, a first protection valve being able to assume a deactivated position or an activated position for placing the first chamber in communication with the high-pressure line, a second protection valve being able to assume a deactivated position or an activated position for placing the second chamber in communication with the low-pressure line, each protection valve comprising a hydraulic activation inlet and a hydraulic deactivation inlet which can be pressurised in order to activate or deactivate these valves. The circuit includes a solenoid protection valve controlling an amplification valve connected to the inlets of the protection valves in order to activate them upon the activation of the solenoid protection valve.
1 . A hydraulic control circuit for actuating a double-acting steering actuator for orienting the blades of an aircraft engine pusher propeller, the double-acting actuator comprising a first and a second chamber, the circuit comprising:
a high-pressure line and a low-pressure line;
a distributing valve for connecting the first chamber to the high-pressure line and the second chamber to the low-pressure line or vice versa, or for isolating the two chambers from the high-pressure and low-pressure lines;
a first protection valve being able to assume a deactivated position or an activation position that places the first chamber in communication with the high-pressure line;
a second protection valve being able to assume a deactivated position or an activation position that places the second chamber in communication with the low-pressure line;
the protection valves include an activation hydraulic inlet and a deactivation hydraulic inlet that can be connected to the high-pressure line or to the low-pressure line to place them in the deactivation or activation position;
an amplification valve being able to assume a deactivated position or an activation position that connects the high-pressure line to each activation inlet and the low-pressure line to each deactivation inlet to activate the protection valves;
the amplification valve including a hydraulic control inlet for placing the amplification valve in the activation position when the control inlet is connected to the low-pressure line and for placing the amplification valve in the deactivated position when the control inlet is connected to the high-pressure line;
and a protection solenoid valve being able to assume a deactivation position or an activation position wherein the protection solenoid valve connects the control inlet of the amplification valve to the low-pressure line in order to activate the amplification valve.
2 . The hydraulic control circuit according to claim 1 , wherein the first and the second protection valve are mechanically coupled and share the same activation hydraulic inlet and the same deactivation hydraulic inlet.
3 . The hydraulic control circuit according to claim 2 , wherein the first and the second protection valve each include a slide valve, and wherein these two slide valves are connected to one another by a rod.
4 . The hydraulic control circuit according to claim 1 , wherein each protection valve is equipped with a return spring tending continuously to return the respective protection valve towards the activation position thereof.
5 . The hydraulic control circuit according to claim 1 , wherein the amplification valve is equipped with a return spring tending continuously to return the amplification valve to the activation position thereof.
6 . The hydraulic control circuit according to claim 1 , wherein the protection valves prevent fluid flow to the first chamber and the second chamber from the distributing valve when the protection valves are activated.