US3893789A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pitch change actuator for a variable pitch fan propulsor
Assignee: RTX Corp
•
Filing: 1973-02-21
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Granted: 1975-07-08
•
Expires: 1993-02-21
Abstract
Abstract Blade angle of a variable pitch ducted fan is varied by transmitting a rotary pitch change mechanical signal across a rotating boundary by a differential gear train for driving a harmonic torque amplifier operatively connected to the root of the fan blades. A one-way rotary device cooperating with the input signal serves to obtain pitch lock.
Inventors
- 👤 Merritt B Andrews
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:04
CPC Classifications
F; F01; F01D; F01D7/00; F05; F05D; F05D2260/00; F05D2260/70; F05D2260/74; F05D2260/76; Y; Y02; Y02T; Y02T50/00; Y02T50/60
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
82 words
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 2
Dependent Claim
82 words
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
Dependent Claim
46 words
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
Dependent Claim
29 words
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
Dependent Claim
36 words
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
Dependent Claim
106 words
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.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-07-07 | 1979-01-06 | 1979-07-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-07 | 1983-01-06 | 1983-07-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-07 | 1987-01-06 | 1987-07-08 | $7700.00 | Window Closed / Lapsed |