Pitch change actuator for a variable pitch fan propulsor

Claim 2

For a ducted fan propulsor having a plurality of circumferentially spaced blades supported in a hub driven by a power plant, pitch change means for imparting rotary motion to said blades for varying the blade angle, said pitch change means including a harmonic drive means operatively connected to said blades, and means secured to a nonrotating element spaced from said hub for imparting a pitch change input signal to actuate said harmonic drive means to position said blades to various blade angles.

Claim 3

For a ducted fan propulsor as claimed in claim 1 wherein said harmonic drive includes a circular spline member, gear teeth formed in said circular spline member, segmented gear teeth formed on the root of said blades engaging said gear teeth on said circular spline member.

Claim 4

For a ducted fan as claimed in claim 1 including a one-way drive element disposed between said input signal imparting means and said harmonic drive to effectuate pitch lock.

Claim 5

For a ducted fan as claimed in claim 1 including a differential gear train operatively connected to said harmonic drive, said input signal imparting means connected to said differential gear train to actuate said harmonic drive.

Claim 6

For a ducted fan propulsor as claimed in claim 4 wherein said differential gear train includes a first sun gear mounted on a nonrotating member, a first ring gear affixed to said harmonic drive and a first set of planetary gears mating said first sun gear and said first ring gear, a second sun gear operatively connected to said input signal so as to be rotated thereby, a second ring gear affixed to said hub and being rotated therewith, a second set of planetary gears mating said second sun gear and said second ring gear, and a carrier interconnecting said first and said second planetary gears.