Emergency collective actuator and method for a helicopter

Patent metadata

Field	Value
Publication number	US-9511856-B2
Application number	US-201414562479-A
Country	US
Kind code	B2
Filing date	Dec 5, 2014
Priority date	Nov 24, 2009
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

A helicopter includes a rotor system having a rotor with an adjustable pitch that is controlled at least in part by a pilot using a collective control and which helicopter generates a Low RPM signal that is indicative of a threshold low rotational speed of the rotor. An actuator arrangement can move the collective control by exerting a force on the collective control such that the pilot is able to overcome the actuator force but which otherwise can move the collective control from a current operational position toward a minimum pitch position. A clutch can co-rotate with a motor to serve in transferring the actuation force to reduce the adjustable pitch and can slip relative to the actuator shaft assembly responsive to an application of a counterforce applied by the pilot to the collective control such that the counterforce overcomes the actuation force.

First claim

What is claimed is:

1. For use with a helicopter including a rotor system having a main rotor with an adjustable pitch that is controlled at least in part by a pilot using a collective control, an apparatus comprising:
an actuator arrangement including a motor having an output shaft for rotation to change the adjustable pitch by exerting an actuation force and a clutch supported by the output shaft and in operative communication with the collective control such that the clutch slips relative to the output shaft to allow the pilot to overcome said actuation force using the collective control but otherwise the clutch co-rotates with the motor shaft to bias the adjustable pitch toward a minimum collective pitch position; and
a control arrangement that is configured to receive a signal that is indicative of a low rotor RPM condition and to respond to said signal by activating the actuator arrangement to exert the actuation force.

2. The apparatus of claim 1 wherein the clutch includes a clutch disk that is supported by the output shaft to co-rotate therewith and a clutch assembly supported by the clutch disk and configured (i) to co-rotate with the clutch disk to serve in transferring the actuation force to reduce the adjustable pitch and (ii) to slip relative to the clutch disk responsive to an application of a counterforce applied by the pilot to the collective control such that the counterforce overcomes the actuation force.

3. The apparatus of claim 2 wherein the clutch assembly includes a clutch housing that defines a clutch housing interior that receives said clutch disk with the clutch housing supported by said clutch disk.

4. The apparatus of claim 1 wherein said control arrangement is further configured to selectively apply the actuation force for a predetermined period of time having a limited duration responsive to receiving said signal.

5. The apparatus of claim 4 wherein said control arrangement is configured to enter a lockout interval immediately following said predetermined period of time during which lockout interval the signal is disabled from activating the actuator arrangement.

6. The apparatus of claim 1 wherein said collective control includes an arm that is pivotable to change the adjustable pitch of the rotor and said arm includes an arm length extending from a pivot end to a distal end and wherein said actuator arrangement is connected to an intermediate position along the arm length to apply said actuation force.

7. The apparatus of claim 6 positioned below said collective control such that said actuation force pulls on said collective control from said intermediate position.

8. The apparatus of claim 7 wherein said actuator arrangement includes a cable having a distal end that is attached to the intermediate position of the arm length for pulling on the collective control to decrease the adjustable pitch.

9. The apparatus of claim 8 wherein the motor is an electric motor for applying said actuation force via the cable by rotating in a given direction.

10. The apparatus of claim 9 wherein said clutch assembly is operatively coupled to a cable drum that is supported for coaxial rotation with said clutch disk and configured for attachment to a proximate end of said cable such that a proximate end portion of said cable extends at least partially around the cable drum.

11. The apparatus of claim 10 wherein said cable drum is resiliently coupled to said clutch assembly by a constant force spring that applies a resilient bias to the cable at least to take up slack in the cable.

12. The apparatus of claim 11 wherein said clutch assembly is rotatable by said motor between a deactivated position at which the actuation force is not applied and an activated position such that rotation of the cable drum from the deactivated position to the activated position retracts the cable to apply the actuation force as needed to move the collective control to the minimum collective pitch position in the absence of a counteracting force from the pilot.

13. The apparatus of claim 12 wherein said deactivated position and said activated position are rotatably spaced apart by less than one full rotation of the clutch assembly.

14. The apparatus of claim 12 wherein said constant force spring applies a resilient bias to the cable to take up slack in the cable with the clutch assembly in the deactivated position.

15. The apparatus of claim 14 wherein said cable drum defines an arcuate groove that receives a clutch pin that is supported by said clutch assembly and, with the clutch assembly in the deactivated position, said cable drum rotates having the clutch pin received in the arcuate groove to provide for a full range of collective control actuation by the pilot as the constant force spring applies said resilient bias to the cable.

16. The apparatus of claim 15 wherein said clutch assembly includes a pair of friction rings arranged on a pair of opposite sides of a clutch disk and said clutch assembly resiliently biases the friction rings against the opposite sides of the clutch disk.

17. The apparatus of claim 15 wherein said arcuate groove includes opposing first and second ends and responsive to rotation of the clutch assembly to the activated position the clutch pin engages the first end of the arcuate groove to rotate the cable drum and thereby retract the cable, as needed, onto the cable drum to bias the adjustable pitch into the minimum collective pitch position.

18. For use with a helicopter including a rotor system having a main rotor with an adjustable pitch that is controlled at least in part by a pilot using a collective control, a method comprising:
receiving an electrical signal that is indicative of a low rotor RPM condition; and
responding to said electrical signal by driving a motor having an output shaft to exert an actuation force by automatically changing the adjustable pitch to exert the actuation force through a clutch such that the pilot is able to overcome said actuation force using the collective control by causing the clutch to slip relative to the output shaft but which actuation force is otherwise applied by co-rotation of the clutch with the output shaft to bias the adjustable pitch toward a minimum collective pitch position.

Assignees

• Merlin Technology Inc

Inventors

• Mercer John E
• Marvin Mark H

Classifications

• B64C27/006

  Safety devices · CPC title

• B64C27/57 Primary

  automatic or condition responsive, e.g. responsive to rotor speed, torque or thrust · CPC title

• B64C27/04

  Helicopters · CPC title

• B64C27/59

  mechanical · CPC title