Helicopter engine control having yaw input anticipation

• US 5,265,825 A
• Filed: 08/26/1992
• Issued: 11/30/1993
• Est. Priority Date: 08/27/1991
• Status: Expired due to Term

• Current Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Driscoll, Joseph T., Sweet, David H., Ebert, Frederick J.
• Primary Examiner(s): Huppert, Michael S.
• Assistant Examiner(s): Ansley, Virna Lissi
• Application Number:
  US07/936,187
• Time in Patent Office: 461 Days
• Field of Search: 244/17.13, 244/17.19, 244/17.21, 244/182, 244/184, 244/195, 416/30, 364/431.07, 364/433, 364/434
• US Class Current: 244/17.13
• CPC Class Codes: G05D 1/0055 with safety arrangements
• CPC Class Codes: G05D 1/0858 specially adapted for vertical take-off of aircraft

Abstract

A helicopter engine fuel control anticipates sudden changes in engine power demand during yaw inputs to thereby minimize engine and main rotor speed droop and overspeed during yaw maneuvers. The rate (121,123) of yaw control (107) position change generates (110) a yaw component (104) of a helicopter fuel control (52) fuel command signal (70). The magnitude of the yaw component is also dependant upon the rate of yaw control position change (703). The fuel command signal yaw component (104) is overridden (113,115) when rotor decay rate (209,217) has been arrested during a sharp left hover turn (216); when the yaw component is removing fuel (239) during rotor droop (238); and when the yaw component is adding fuel (228) during rotor overspeed (227).

Claims

1. A helicopter comprising:

a main rotor;

a tail rotor having a plurality of blades;

an engine

rotor drive means including an overrunning clutch for connecting said main rotor to said engine whenever the speed of said main rotor does not exceed the speed of said engine;

pilot operated yaw controls for providing a yaw command signal indicative of the relative position of said pilot operated yaw controls, said yaw command signal controlling the pitch angle of said tail rotor blades; and

engine control means for providing a fuel command signal indicative of fuel flow required for desired engine operation, and for metering fuel flow to said engine in response to said fuel command signal;

characterized by,

means for providing a yaw command rate signal indicative of the rate of change of said yaw command signal; and

said engine control means comprising means for providing said fuel command signal with a yaw component in response to said yaw command rate signal.

2. A helicopter according to claim 1, further characterized by said fuel command signal yaw component increasing fuel flow to said engine in response to a commanded yaw maneuver in the direction of main rotor rotation and said yaw input rate signal being in excess of a first predetermined threshold rate, and said fuel command signal yaw component decreasing fuel flow to said engine in response to a commanded yaw maneuver opposite the direction of main rotor rotation and said yaw input rate signal being in excess of a second predetermined threshold rate.

3. A helicopter according to claim 2 wherein said engine control means further comprises means for providing an override signal for overriding said fuel command signal yaw component.

4. A helicopter according to claim 3 further comprising:

rotor speed means for providing a rotor speed signal indicative of the rotary speed of said rotor; and

said override signal being provided in response to said rotor speed signal being in excess of a first rotor speed threshold and said fuel command signal yaw component increasing fuel flow to said engine, or said rotor speed signal being below said first rotor speed threshold and said fuel command signal yaw component decreasing fuel flow to said engine.

5. A helicopter according to claim 4 further comprising:

rotor acceleration means for providing a rotor acceleration signal indicative of the positive or negative acceleration of said rotor;

helicopter speed means for providing a helicopter speed signal indicative of the speed of the helicopter;

means for providing a helicopter turn signal indicative of the rate that the helicopter is turning;

fuel rate means for providing a fuel rate signal indicative of the rate that fuel is being supplied to said engine; and

said override signal being further provided in response to said rotor acceleration signal being indicative of positive acceleration, said rotor speed signal being in excess of a second rotor speed threshold, said fuel rate signal being in excess of a fuel threshold rate, said helicopter speed being below a helicopter threshold speed and said turn signal being below a turn threshold rate.

6. A helicopter according to claim 1 wherein said engine control means further comprises:

rotor speed means for providing a rotor speed signal indicative of the rotary speed of said rotor;

rotor acceleration means for providing a rotor acceleration signal indicative of the positive or negative acceleration of said rotor; and

means for providing said fuel command signal with a rotor droop component which decreases fuel flow to said engine when said rotor speed signal is below a third rotor speed threshold and said rotor acceleration signal is indicative of positive acceleration and in excess of a threshold acceleration, to thereby limit said rotor speed signal exceeding said third rotor speed threshold.

7. A helicopter according to claim 6 wherein said fuel command signal rotor droop component is a function of said rotor speed signal and said rotor acceleration signal.

8. A helicopter comprising:

a main rotor;

a tail rotor having a plurality of blades;

an engine;

rotor drive means including an overrunning clutch for connecting said main rotor to said engine whenever the speed of said main rotor does not exceed the speed of said engine;

pilot operated yaw controls for providing a yaw command signal indicative of the relative position of said pilot operated yaw controls said yaw command signal controlling the pitch angle of said tail rotor blades; and

means for providing a yaw command rate signal indicative of the rate of change of said yaw command signal;

engine control means for providing a fuel command signal indicative of fuel flow required for desired engine operation, and for metering fuel flow to said engine in response to said fuel command signal;

means for providing a fuel compensation signal the magnitude and duration of which are dependent upon said yaw command rate signal; and

said engine control means comprising means for combining said fuel compensation signal with said fuel command signal.

9. A helicopter according to claim 8 wherein said fuel compensation signal increases fuel flow to said engine in response to a commanded yaw maneuver in the direction of main rotor rotation, and said fuel command signal yaw component decreases fuel flow to said engine in response to a commanded yaw maneuver opposite the direction of main rotor rotation.

10. A helicopter according to claim 8 further comprising limiting means for providing a first limit 49 for limiting the magnitude of said fuel compensation signal when it is increasing fuel flow 57 to said engine, and for providing a second limit for limiting the magnitude of said fuel compensation signal when it is decreasing the fuel flow to said engine.

11. A helicopter according to claim 10 further comprising:

means for providing an engine speed signal indicative of the rate of change in engine speed 177; and

said limiting means second limit being determined as a function of said engine speed signal.

12. A helicopter according to claim 8 further comprising:

means for providing an air speed multiple as a function of helicopter airspeed; and

means for multiplying said fuel compensation signal by said airspeed multiple prior to combining said fuel compensation signal with said fuel command signal.

13. A helicopter according to claim 12 wherein said air speed multiple is set equal to zero when said helicopter airspeed is above a threshold magnitude and when said helicopter is on its landing gear.

14. A helicopter according to claim 8 wherein said engine control means further comprises means for providing an override signal for preventing the combination of said fuel compensation signal with said fuel command signal.

15. A helicopter according to claim 14 further comprising:

means for providing an engine speed signal indicative of the speed of said engine;

means for providing an engine acceleration signal indicative of the rate of change of said engine speed signal; and

said override signal being provided in response to said engine speed signal being indicative of engine speed above a threshold magnitude, said engine acceleration signal being indicative of engine acceleration above a threshold magnitude, and said fuel compensation signal adding fuel;

in response to said engine speed signal being indicative of engine speed above a threshold magnitude and said engine acceleration signal being indicative of engine deceleration;

or in response to said engine speed signal being indicative of engine speed below a threshold magnitude and said fuel compensation signal removing fuel.