Patent US4084749A successfully refreshed from Google Patents.
Patent US3873235A successfully refreshed from Google Patents.
US3873235A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable pitch turbofan engine
Assignee: General Electric Co
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Filing: 1973-10-01
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Granted: 1975-03-25
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Expires: 1993-10-01
Abstract
Abstract A turbofan engine is provided with an actuator for varying the fan pitch angle by rotating individual fan blades within apertures in an associated fan disc. The actuator includes a shaft, a sleeve circumscribing the shaft, and a casing receiving both the shaft and the sleeve. Means between the casing and the blade shank rotate the blade (to change its pitch) in response to relative rotation between the casing and the shaft. In order to lock the fan blades in selected pitches between pitch changes, a pitch lock is provided which utilizes a locking piston and a thrust collar cooperating respectively with the casing and the shaft and incorporating interlocking releasable teeth. The locking piston is biased by spring means into a locking relationship with the thrust collar so that if pressure is lost in a main actuating cylinder (within which both the locking piston and an actuator piston are disposed), a fail-safe pitch locked status is assumed by the fan. In order to sense the pitch angle, means are provided for reading the axial position of the actuator piston and, hence, the pitch angle of the fan at any given instant.
Inventors
- 👤 Irwin Mendelson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:51
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: 14
Claim 1
Independent Claim
253 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 longitudinal 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 including: a shaft coAxial and rotatable with said disc, the shaft secured in a predetermined relationship with the disc; a sleeve located radially outward of and telescopically receiving the shaft, the sleeve being axially translatable with respect to the shaft; a casing located radially outward of the sleeve, and telescopically receiving the shaft and the 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 cooperating with the sleeve for causing translation of the sleeve in response to a predetermined signal; first recirculating ball spline means disposed between the shaft and the sleeve at a predetermined first helix angle for permitting said sleeve translation; and second recirculating ball spline means disposed between the sleeve and the casing at a predetermined second helix angle for rotating said casing in response to translation of said sleeve.
Claim 2
Dependent Claim
253 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 longitudinal 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 including: a shaft coAxial and rotatable with said disc, the shaft secured in a predetermined relationship with the disc; a sleeve located radially outward of and telescopically receiving the shaft, the sleeve being axially translatable with respect to the shaft; a casing located radially outward of the sleeve, and telescopically receiving the shaft and the 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 cooperating with the sleeve for causing translation of the sleeve in response to a predetermined signal; first recirculating ball spline means disposed between the shaft and the sleeve at a predetermined first helix angle for permitting said sleeve translation; and second recirculating ball spline means disposed between the sleeve and the casing at a predetermined second helix angle for rotating said casing in response to translation of said sleeve.
Claim 3
Dependent Claim
23 words
The fan of claim 1 wherein said first means includes a pinion carried by the casing and a gear carried by the shank.
Claim 4
Dependent Claim
42 words
The fan of claim 1 wherein said second means includes a cylinder, an actuating piston cooperating with the sleeve and disposed within the cylinder and third means for providing a pressure differential across the actuating piston to displace it within the cylinder.
Claim 5
Dependent Claim
16 words
The fan of claim 1 wherein said first and second helix angles are of opposite sense.
Claim 6
Dependent Claim
64 words
The variable pitch fan of claim 1 further incuding a pitch lock comprising: a thrust collar cooperating with said shaft,; a locking piston cooperating with said casing; first locking means associated with said collar; second locking means associated with said piston; retaining means for providing engagement between said first and second locking means; and release means for releasing said first and second locking means.
Claim 7
Dependent Claim
30 words
The pitch lock of claim 5 wherein: said thrust collar is fixed circumferentially with respect to said shaft; and said locking piston is fixed circumferentially with respect to said casing.
Claim 8
Dependent Claim
18 words
The pitch lock of claim 6 wherein: said locking piston is axially movable with respect to said casing.
Claim 9
Dependent Claim
40 words
The pitch lock of claim 7 wherein said retaining means comprises spring means providing an engaging bias between said first and second locking means; and said release means includes means for providing a disengaging pressure differential across said locking piston.
Claim 10
Dependent Claim
26 words
The pitch lock of claim 8 wherein said first and second locking means include corresponding teeth carried respectively by said thrust collar and said locking piston.
Claim 11
Dependent Claim
41 words
The pitch lock of claim 11 wherein said locking piston is movable against said spring means responsive to a pressure differential imposed thereacross between a first position wherein said teeth are engaged and a second position wherein said teeth are disengaged.
Claim 12
Dependent Claim
60 words
The pitch lock of claim 8 wherein said second means includes a cylinder, an actuating piston secured with respect to the sleeve and disposed within the cylinder, and third means for providing a pressure differential across the actuating piston to displace it within the cylinder; and wherein said third means also provides said disengaging pressure differential across said locking piston.
Claim 13
Dependent Claim
15 words
The pitch lock of claim 11 wherein said locking piston is disposed within said cylinder.
Claim 14
Dependent Claim
51 words
The pitch lock of claim 11 wherein said spring means biases said locking piston toward a position in which said first and second locking means are in a locking engagement; and failure of the third means to provide a pressure differential across said locking piston results in said pitch locked engagement.
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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) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |