Quad mode fan pitch actuation system for a gas turbine engine
AssigneeAlliedSignal Inc.
InventorsFrederick B. McCarty, Thomas F. Fitzgibbon
Life of this patent
Estimating the term…
Abstract
Blade pitch is changed by an actuator that is responsive to the relative rotation of two input members. Blade pitch is not changed when the members are rotated at the same speed. However, blade pitch is changed in one direction when a braking torque is applied to one member, and blade pitch is changed in an opposite direction when a braking torque is applied to the other member.
Claims17
Apparatus for controlling variable blade pitch of a turbine engine including a turbine shaft and a plurality of fan blades, said apparatus comprising:
- a first member relatively rotatable with respect to said shaft;
- a second member relatively rotatable with respect to said shaft;
- differential gear means for interengaging with said first and second members and for providing a translational output in response to rotation of said first and second members relative to said shaft;
- linkage means for receiving said translational output of said differential gear means and for converting and transmitting said translational output to said fan blades to affect a pitch change of said fan blades;
- first actuator means for selectively causing rotation of said first member relative to said shaft and thereby effecting a pitch change of said fan blades in a first direction;
- and
- second actuator means for selectively causing rotation of said second member relative to said shaft and thereby effecting a pitch change of said fan blades in a direction opposite said first direction.
A method of operating a differential electromagnetic induction fan blade pitch system having two induction motors, each said induction motor including a rotor and a stator, said method comprising the steps of;
- selectively energizing either one of the stators to alter fan blade pitch in opposite senses when the fan is rotating and a first mode of operation is selected;
- selectively energizing both of the stators simultaneously such that both rotors transmit torque to rotate the fan for assisting in starting fan rotation when a second mode of operation is selected;
- selectively energizing at least one of the stators to drive the fan to a reverse pitch position when a third mode of operation is selected whereby the rotating fan creates a reverse thrust;
- and
- driving both rotors by the engine during normal fan operation to generate auxiliary electrical power when a fourth mode of operation is selected.
Apparatus for rotating at least one output member in response to relative rotation between first and second input members, comprising;
- a planetary gear train having first and second input gears coupled to said first and second input members and having an output driven in response to relative rotation between said first and second input members;
- a drive plate member engaging said output of said planetary gear train;
- ball screw means, including a ball screw secured to said drive plate member and ball nuts threadedly engaging said ball screw and moving axially on said ball screw in response to rotation of said ball screw by said drive plate member;
- and
- a yoke member corresponding to each output member, each said yoke member being coupled to said ball nuts for rotating said corresponding output member when said ball nuts move axially on said ball screw.
Dependencies are inferred from the claim text.