US3994128A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dual output variable pitch turbofan actuation system
Assignee: National Aeronautics and Space Administration
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Filing: 1975-05-21
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Granted: 1976-11-30
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Expires: 1995-05-21
Abstract
Abstract An improved actuating mechanism is provided for a gas turbine engine incorporating fan blades of the variable pitch variety, the actuator adapted to rotate the individual fan blades within apertures in an associated fan disc. The actuator includes means such as a pair of synchronizing ring gears, one on each side of the blade shanks, and adapted to engage pinions disposed thereon. Means are provided to impart rotation to the ring gears in opposite directions to effect rotation of the blade shanks in response to a predetermined input signal. In the event of system failure, a run-away actuator is prevented by an improved braking device which arrests the mechanism.
Inventors
- 👤 Robert H. Griswold, Jr.
- 👤 Carl L. Broman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 07:44
CPC Classifications
F; F04; F04D; F04D29/00; F04D29/26; F04D29/32; F04D29/321; F04D29/322; F04D29/323; F01; F01D; F01D7/00; F02; F02C; F02C7/00; F02C7/36; F02K; F02K3/00; F02K3/02; F02K3/04; F02K3/06; B; B64; B64D; B64D27/00; B64D2027/005; F05; F05D; F05D2220/00; F05D2220/30; F05D2220/36; F05D2260/00; F05D2260/40; F05D2260/403; F05D2260/4031; F05D2260/70; F05D2260/74; F05D2260/79; Y; Y02; Y02T; Y02T50/00; Y02T50/60
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
371 words
In a turbofan engine of the variety including an annular fan duct, a core engine disposed internally of the fan duct and comprising a compressor, a combustion chamber and a turbine, a variable pitch fan comprising: a fan disc, generally circular in peripheral shape, rotatable about its axis and having a plurality of apertures in its periphery; a fan blade disposed within said duct and including a shank adapted to penetrate one of said apertures; bearing means interconnecting said shank and said one aperture and permitting relative rotation therebetween; and pitch varying means for rotating said shank comprising: a shaft coaxial and rotatable with said disc, the shaft secured in a predetermined axial relationship with the disc; a first sleeve telescopically receiving the shaft, said first sleeve being axially translatable with respect to and rotatable about the shaft; a second sleeve telescopically received in the first sleeve, said second sleeve being rotatable within said first sleeve and about said shaft; a casing telescopically receiving the shaft, the first sleeve and the second sleeve, the casing being rotatable about the shaft; first means carried by the casing for rotating said blade shank in response to rotation of the casing about the shaft; second means carried by the second sleeve and cooperating with said first means for rotating said blade shank in response to rotation of said second sleeve with respect to said first sleeve; third means cooperating with the first sleeve and the shaft for causing rotation and translation of the first sleeve in response to differential rotation of the shaft with respect to the disc; first mating means disposed between the first sleeve and the casing and having a predetermined first helix angle for permitting said first sleeve to translate with respect to the casing and the casing to rotate about the shaft; thrust bearing means carried between the shaft and second sleeve; and second mating means operatively connecting the first sleeve and the second sleeve and having a predetermined second helix angle for permitting said rotation about the first sleeve and the shaft, and wherein the shaft, the first and second sleeves, the second mating means, and the thrust bearing means are interconnected to form a closed axial thrust loop.
Claim 2
Dependent Claim
371 words
In a turbofan engine of the variety including an annular fan duct, a core engine disposed internally of the fan duct and comprising a compressor, a combustion chamber and a turbine, a variable pitch fan comprising: a fan disc, generally circular in peripheral shape, rotatable about its axis and having a plurality of apertures in its periphery; a fan blade disposed within said duct and including a shank adapted to penetrate one of said apertures; bearing means interconnecting said shank and said one aperture and permitting relative rotation therebetween; and pitch varying means for rotating said shank comprising: a shaft coaxial and rotatable with said disc, the shaft secured in a predetermined axial relationship with the disc; a first sleeve telescopically receiving the shaft, said first sleeve being axially translatable with respect to and rotatable about the shaft; a second sleeve telescopically received in the first sleeve, said second sleeve being rotatable within said first sleeve and about said shaft; a casing telescopically receiving the shaft, the first sleeve and the second sleeve, the casing being rotatable about the shaft; first means carried by the casing for rotating said blade shank in response to rotation of the casing about the shaft; second means carried by the second sleeve and cooperating with said first means for rotating said blade shank in response to rotation of said second sleeve with respect to said first sleeve; third means cooperating with the first sleeve and the shaft for causing rotation and translation of the first sleeve in response to differential rotation of the shaft with respect to the disc; first mating means disposed between the first sleeve and the casing and having a predetermined first helix angle for permitting said first sleeve to translate with respect to the casing and the casing to rotate about the shaft; thrust bearing means carried between the shaft and second sleeve; and second mating means operatively connecting the first sleeve and the second sleeve and having a predetermined second helix angle for permitting said rotation about the first sleeve and the shaft, and wherein the shaft, the first and second sleeves, the second mating means, and the thrust bearing means are interconnected to form a closed axial thrust loop.
Claim 3
Dependent Claim
25 words
The fan of claim 1 wherein said first means includes a first ring gear carried by the casing and a pinion carried by the shank.
Claim 4
Dependent Claim
26 words
The fan of claim 1 wherein said second means includes a second ring gear carried by the second sleeve and the pinion carried by the shank.
Claim 5
Dependent Claim
25 words
The fan of claim 1 wherein said third means includes first threads disposed upon the shaft and cooperating second threads disposed upon the first sleeve.
Claim 6
Dependent Claim
21 words
The fan of claim 1 wherein said third means includes ball screw means disposed between the shaft and the first sleeve.
Claim 7
Dependent Claim
17 words
The fan of claim 1 wherein said first mating means comprises a first recirculating ball spline means.
Claim 8
Dependent Claim
17 words
The fan of claim 1 wherein said second mating means comprises a second recirculating ball spline means.
Claim 9
Dependent Claim
15 words
The fan of claim 1 wherein said first helix angle is a zero helix angle.
Claim 10
Dependent Claim
26 words
The fan of claim 1 further including retainer means cooperating with said first means and said second means to prevent axial displacement therebetween under centrifugal loading.
Claim 11
Dependent Claim
26 words
The fan of claim 2 wherein said second means includes a second ring gear carried by the second sleeve and the pinion carried by the shank.
Claim 12
Dependent Claim
52 words
The fan of claim 10 further including retainer means, and wherein said retainer means includes first shoulder means carried by said first means; and second shoulder means carried by said second means and adapted to cooperate with said first shoulder means through a bearing surface therebetween to prevent relative axial displacement thereof.
Claim 13
Dependent Claim
31 words
The fan of claim 9 wherein the first ring gear and the second ring gear are axially disposed on opposite sides of the shank and adapted to rotate in opposite directions.
Claim 14
Dependent Claim
27 words
The fan of claim 1 further including brake means connected to the shaft for limiting circumferential travel of said pitch changing means with respect to the shaft.
Claim 15
Dependent Claim
78 words
The fan of claim 13 wherein said brake means is of the disc brake variety, comprising a first plurality of radially extending, axially spaced discs fixedly connected to the shaft, a second plurality of radially extending, axially spaced discs in alternating frictional engagement with the first plurality of discs; and means for engaging the first sleeve with the second plurality of discs to impart rotation thereto when the first sleeve has substantially reached its limit of axial travel.
Claim 16
Dependent Claim
22 words
The fan of claim 14 further including stop means fixedly connected to the shaft to limit axial movement of said first sleeve.
Claim 17
Dependent Claim
54 words
The fan of claim 13 further including: first teeth carried by the shaft; and second teeth carried by the first sleeve and adapted to mechanically engage said first teeth when the first sleeve exceeds a predetermined axial travel and whereby rotational energy of the pitch varying means is absorbed by torsion of said shaft.
Claim 18
Dependent Claim
52 words
The fan of claim 14 wherein the engaging means comprises a carrier slidingly splined to the second plurality of discs, the carried including a first plurality of teeth which engage a cooperating second plurality of teeth on the first sleeve when the first sleeve has substantially reached its limit of axial travel.
Claim 19
Dependent Claim
187 words
An actuator for changing the pitch of a fan blade carried by a rotatable disc comprising: a shaft coaxial with the disc and secured in a constant axial spacial relationship therewith; motor means driving said shaft at a differential rotational speed with respect to the disc; a sleeve telescopically receiving the shaft and operatively connected to a ring gear which engages a sector gear connected to the blade to effect the pitch change thereof; a recirculating ball actuator to drive the sleeve linearly and rotationally with respect to the shaft, thereby imparting rotational motion to the ring gear; brake means connected to the shaft for limiting the rotational travel of the sleeve with respect to the shaft, wherein said brake means is of the disc variety, comprising a first plurality of radially extending, axially spaced discs fixedly connected to the shaft, a second plurality of radially extending, axially spaced discs in alternating frictional engagement with the first plurality of discs; and means for engaging the sleeve with the second plurality of discs to impart rotation thereto when the sleeve has substantially reached its limit of linear travel.
Claim 20
Dependent Claim
187 words
An actuator for changing the pitch of a fan blade carried by a rotatable disc comprising: a shaft coaxial with the disc and secured in a constant axial spacial relationship therewith; motor means driving said shaft at a differential rotational speed with respect to the disc; a sleeve telescopically receiving the shaft and operatively connected to a ring gear which engages a sector gear connected to the blade to effect the pitch change thereof; a recirculating ball actuator to drive the sleeve linearly and rotationally with respect to the shaft, thereby imparting rotational motion to the ring gear; brake means connected to the shaft for limiting the rotational travel of the sleeve with respect to the shaft, wherein said brake means is of the disc variety, comprising a first plurality of radially extending, axially spaced discs fixedly connected to the shaft, a second plurality of radially extending, axially spaced discs in alternating frictional engagement with the first plurality of discs; and means for engaging the sleeve with the second plurality of discs to impart rotation thereto when the sleeve has substantially reached its limit of linear travel.
Claim 21
Dependent Claim
23 words
The actuator as recited in claim 18 further comprising stop means fixedly connected to the shaft to limit linear travel of the sleeve.
Claim 22
Dependent Claim
53 words
The actuator as recited in claim 18 wherein the engaging means comprises a carrier slidingly splined to the second plurality of discs, the carrier including a first plurality of teeth which engage a cooperating second plurality of teeth on the sleeve when the sleeve has substantially reached its limit of linear travel. l
Claim 23
Dependent Claim
26 words
The actuator as recited in claim 20 wherein the carrier engages a stop means fixedly connected to the shaft to limit linear travel of the sleeve.
Claim 24
Dependent Claim
29 words
The actuator as recited in claim 21 wherein the stop means comprises a radial extension of the shaft and a spring disposed between the radial extension and the carrier.
Claim 25
Dependent Claim
57 words
The actuator as recited in claim 18 wherein said brake means comprises a first plurality of teeth fixedly carried by the shaft which engage a second plurality of teeth on the sleeve when the sleeve reaches a predetermined linear travel such that rotational energy of the actuator is absorbed through the sleeve by torsion of the shaft.
References Cited (Backward Citations)
US1890932A
Cited
US2679299A
Cited
US3687569A
Cited
US3802799A
Cited
US3825370A
Cited
US3873235A
Cited
US3866415A
Cited
US3900274A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-11-30 | 1980-05-31 | 1980-11-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-11-30 | 1984-05-31 | 1984-11-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-11-30 | 1988-05-31 | 1988-11-30 | $7700.00 | Window Closed / Lapsed |