Propeller pitch control system for aircraft turboprop engines

Patent metadata

Field	Value
Publication number	US-10850831-B2
Application number	US-201816230201-A
Country	US
Kind code	B2
Filing date	Dec 21, 2018
Priority date	Dec 21, 2018
Publication date	Dec 1, 2020
Grant date	Dec 1, 2020

Abstract

A propeller pitch control system for a turboprop engine of an aircraft includes an engine control unit and a pitch control unit. The engine control unit is operable to determine a phase of flight of the aircraft and is configured to supply control commands. The pitch control unit is coupled to receive the control commands from the engine control unit and includes a housing, a beta piston, a position sensor, a beta tube, and an electrohydraulic valve. The engine control unit only commands the electrohydraulic valve to move the beta piston from the fully retracted position when the engine control unit determines the aircraft is conducting pre-takeoff roll taxiing operations or is conducting post landing touchdown operations.

First claim

What is claimed is:

1. A propeller pitch control system for a turboprop engine of an aircraft, comprising:
an engine control unit operable to determine a phase of flight of the aircraft and configured to supply control commands; and
a pitch control unit coupled to receive the control commands from the engine control unit, the pitch control unit comprising:
a housing including an inlet port, a drain pressure port, a control pressure chamber, and a piston sleeve, the inlet port for receiving hydraulic fluid, the drain pressure port vented to atmospheric pressure;
a beta piston disposed within the piston sleeve and axially movable therein between a fully extended position and a fully retracted position, the beta piston having a first end section, a second end section, an inner surface, an outer surface, and a control pressure port, at least a portion of the second end section disposed within the control pressure chamber, the second end section having an outer surface and being frustoconical in cross-section, the inner surface defining a beta tube control volume, the control pressure port extending between the inner surface and the outer surface and fluidly communicating the inlet port with the beta tube control volume;
a position sensor having a sensor housing and a sensor shaft, the shaft extending from, and movable relative to, the housing and spring biased to continuously engage the outer surface of the second end section, whereby axial movement of the second end section causes the sensor shaft to move relative to the sensor housing;
a beta tube disposed within the beta tube control volume and rotatable relative to the beta piston, the beta tube axially movable in the beta tube control volume based, at least in part, on fluid pressure within the beta tube control volume; and
an electrohydraulic valve coupled to the housing and including a supply nozzle, a drain nozzle, a control pressure port, a movable flapper disposed between the supply nozzle and the drain nozzle, and a torque motor coupled to the flapper, the supply nozzle in fluid communication with the inlet port, the drain nozzle in fluid communication with the drain pressure port, the control pressure port in fluid communication with the control pressure chamber, the torque motor coupled to receive commands from the engine control unit and responsive to the commands to move the flapper between the supply nozzle and the drain nozzle to modulate fluid pressure in the control pressure chamber, to thereby move the beta piston to the fully extended position, the fully retracted position, or any one of numerous positions between the fully extended and fully retracted positions,
wherein:
when the beta piston is in the fully retracted position, the second end section engages a wall of the control pressure chamber, and
the engine control unit only commands the electrohydraulic valve to move the beta piston from the fully retracted position when the engine control unit determines the aircraft is conducting pre-takeoff roll taxiing operations or is conducting post landing touchdown operations.

2. The propeller pitch control system of claim 1 , wherein the beta piston and the beta tube are configured to form a half-area force balanced architecture.

3. The propeller pitch control system of claim 2 , wherein:
the beta piston has an outer diameter (D BP_OUTER ) that defines a first area (A 1 );
the beta tube has an outer diameter (D BT_OUTER ) that defines a second area (A 2 );
a difference between the first area (A 1 ) and the second area (A 2 ) is approximately equal to a third area (A 3 ); and
the third area (A 3 ) is equal to the second area (A 2 ).

4. The propeller pitch control system of claim 3 , wherein the beta piston is in a force balance position when fluid pressure in the control pressure chamber is approximately half of fluid pressure in the beta tube control volume.

5. The propeller pitch control system of claim 1 , wherein the beta tube comprises:
an inner surface and an outer surface, the inner surface defining a propeller pitch control volume;
a first aperture disposed at a first axial position on the beta tube and extending between the inner surface and the outer surface; and
a second aperture disposed at a second axial position on the beta tube extending between the inner surface and the outer surface, the second axial position spaced apart from the first axial position.

6. The propeller pitch control system of claim 5 , wherein fluid pressure in the propeller pitch control volume is modulated by axially moving the beta tube in the beta tube control volume.

7. The propeller pitch control system of claim 6 , wherein:
the beta tube is axially movable in the beta tube control volume to a plurality of first positions, a plurality of second positions, and a plurality of third positions;
the plurality of first positions include axial positions of the beta tube in which (i) the first aperture fluidly communicates the propeller pitch control volume to the beta tube control volume and (ii) the second aperture fluidly communicates the propeller pitch control volume to atmospheric pressure;
the plurality of second positions include axial positions of the beta tube in which (i) the first aperture fluidly communicates the propeller pitch control volume to the beta tube control volume and (ii) the second aperture is blocked; and
the plurality of third positions include axial positions of the beta tube in which the first aperture and the second aperture both fluidly communicate the propeller pitch control volume to the beta tube control volume.

8. The propeller pitch control system of claim 1 , wherein the position sensor comprises a linear variable different transformer (LVDT) sensor.

9. The propeller pitch control system of claim 1 , further comprising:
a slot formed in the housing;
an anti-rotation pin coupled to the second end section of the beta piston and extending into the slot, whereby rotation of the beta piston is prevented.

10. The propeller pitch control system of claim 1 , wherein:
the second end section of the beta piston is defined by a first frustoconical end and a second frustoconical end;
the second end section increases in diameter from the first frustoconical end to the the second frustoconical end; and
the second frustoconical end engages a wall of the control pressure chamber when the beta piston is in the fully retracted position.

11. A propeller pitch control system for a turboprop engine of an aircraft, comprising:
an engine control unit operable to determine a phase of flight of the aircraft and configured to supply control commands; and
a pitch control unit coupled to receive the control commands from the engine control unit, the pitch control unit comprising:
a housing having a slot formed therein and including an inlet port, a drain pressure port, a control pressure chamber, and a piston sleeve, the inlet port for receiving hydraulic fluid, the drain pressure port vented to atmospheric pressure;
a beta piston disposed within the piston sleeve and axially movable therein between a fully extended position and a fully retracted position, the beta piston having a first end section, a second end section, an inner surface, an outer surface, and a control pressure port, at least a portion of the second end section disposed within the control pressure chamber, the second end section having an outer surface and being frustoconical in cross-section, the inner surface defining a beta tube control volume, the control pressure port extending between the inner surface and the outer surface and fluidly communicating the inlet port with the beta tube control volume;
an anti-rotation pin coupled to the s

Assignees

• Honeywell Int Inc

Inventors

• Futa Jr Paul W
• Tillich Sammuel
• Lewis Steven Alan
• Eick Christopher Douglas
• Striker Donald
• Mcpherson Michael Albert

Classifications

• B64C11/38

  fluid, e.g. hydraulic · CPC title

• B64C11/303

  characterised by comprising a governor · CPC title

• B64C11/40 Primary

  automatic · CPC title

• B64C11/305 Primary

  characterised by being influenced by other control systems, e.g. fuel supply · CPC title