US3794442A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable pitch rotary blading
Assignee: SECR DEFENCE
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Filing: 1972-04-17
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Granted: 1974-02-26
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Expires: 1992-04-17
Abstract
Abstract The centrifugal turning moments on a variable pitch fan blade are counter balanced by the centrifugal force on a cam follower member which is reacted by a cam member connected to the blade to provide a turning moment on the blade opposite to the centrifugal turning moment. The cam member is a cylinder surrounding the blade root and having at least one cam track. A reaction member in the form of a second cylinder concentric with the cam member and having oppositely inclined corresponding cam tracks is connected to structure stationary relative to the blade. The cam follower member is a roller engaging the cam tracks on both the cam member and the reaction member.
Inventors
- 👤 Murtry D Mc
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 03:39
CPC Classifications
F; F01; F01D; F01D7/00; F05; F05D; F05D2220/00; F05D2220/30; F05D2220/36; F05D2260/00; F05D2260/70; F05D2260/74; F05D2260/76
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
202 words
Variable pitch rotary blading comprising a rotor mounted for rotation about a main axis, a plurality of blades each having a root portion and means for rotatably mounting said root portion on the rotor for rotation of the blade about its longitudinal axis to vary the pitch thereof, there being provided in association with each blade a pair of concentric cylindrical members mounted to surround the root portion of the blade, one of the members being mounted for rotation with the root portion about the longitudinal axis of the blade, the other of the members being mounted on the rotor in a fixed position relative thereto, one of the members having means defining at least one slot therein, the other of the members having at least one corresponding slot therein, said slot defining a pair of oppositely inclined cam surfaces one on each member, a roller engaging both cam surfaces of a said pair, the roller being movable under centrifugal force due to rotation of the rotor about the main axis, the cam surfaces being profiled to provide a turning moment on the blade derived from the radial movement of the roller to oppose the centrifugal turning moment of the blade itself.
Claim 2
Dependent Claim
202 words
Variable pitch rotary blading comprising a rotor mounted for rotation about a main axis, a plurality of blades each having a root portion and means for rotatably mounting said root portion on the rotor for rotation of the blade about its longitudinal axis to vary the pitch thereof, there being provided in association with each blade a pair of concentric cylindrical members mounted to surround the root portion of the blade, one of the members being mounted for rotation with the root portion about the longitudinal axis of the blade, the other of the members being mounted on the rotor in a fixed position relative thereto, one of the members having means defining at least one slot therein, the other of the members having at least one corresponding slot therein, said slot defining a pair of oppositely inclined cam surfaces one on each member, a roller engaging both cam surfaces of a said pair, the roller being movable under centrifugal force due to rotation of the rotor about the main axis, the cam surfaces being profiled to provide a turning moment on the blade derived from the radial movement of the roller to oppose the centrifugal turning moment of the blade itself.
Claim 3
Dependent Claim
43 words
Variable pitch rotary blading as claimed in claim 1 wherein the cylindrical members around one blade root have means defining three slots to provide three pairs of oppositely inclined cam surfaces and three rollers are provided one for each pair of cam surfaces.
Claim 4
Dependent Claim
52 words
Variable pitch rotary blading according to claim 1 and wherein the cam surfaces are additionally profiled so that the turning moment produced on each blade by the roller substantially balances the sum of the centrifugal turning moments on the blades and the turning moments due to the gas loads on the blades.
Claim 5
Dependent Claim
54 words
Variable pitch rotary blading according to claim 1 and wherein the cam surfaces are profiled so thAt the turning moments produced on the blades by the rollers are slightly greater than the centrifugal turning moments on the blades so that there is a net moment tending to turn the blades into the feathered position.
References Cited (Backward Citations)
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US2460559A
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US2514477A
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US2533358A
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US2477954A
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US3663119A
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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) | 1977-02-25 | 1977-08-27 | 1978-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-25 | 1981-08-27 | 1982-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-25 | 1985-08-27 | 1986-02-26 | $7700.00 | Window Closed / Lapsed |