US4449360A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stall detector and surge prevention feature for a gas turbine engine
Assignee: Aviation Electric Ltd
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Filing: 1981-04-30
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Granted: 1984-05-22
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Expires: 2001-04-30
Abstract
Abstract A proportional fuel fuel control (11) regulates the fuel flow (Wf) from a hydromechanical unit (36) based upon an error signal (E) representing the difference between a demanded speed signal (Nd) and an actual speed signal (Nh). The demanded speed signal (Nd) is generated by an integrator (32) as the time integral of the least of a plurality of acceleration terms (Aa, Ab, Ac, Ad) selected by a select low gate (38). The demanded acceleration term (Aa) is generated by junction (26) as the difference between the demanded signal (Nd) and a scheduled speed signal (Ngs). Stress acceleration terms (Ac, Ad) are generated by junctions (48, 50) and scheduling means (42, 44) which form stress limiter circuits. A stall acceleration term (Ab) is generated by a junction (46) and a scheduling means (40) which forms a stall prevention feature.
Inventors
- 👤 Rowland M. Evans
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 01:04
CPC Classifications
F; F02; F02C; F02C9/00; F02C9/26; F02C9/28; F05; F05D; F05D2270/00; F05D2270/01; F05D2270/04; F05D2270/10; F05D2270/101
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
181 words
A fuel control system for a gas turbine engine comprising: means for generating an actual speed signal proportional to the actual turbine speed of the gas turbine engine; means for generating a scheduled speed signal proportional to a desired output power; means for generating a demanded speed signal proportional to the time integral of a difference signal; means for generating said difference signal proportional to the difference between said scheduled speed signal and said demanded speed signal; means for generating an error signal proportional to the difference between said demanded speed signal and said actual speed signal; means for controlling the fuel flow to the gas turbine engine as a function of said error signal; means for generating a stall factor as a function of the difference between the rate of change of the demanded speed signal and the rate of change of the actual speed signal, said stall factor being indicative of the degree of stall the engine is experiencing; and means for modifying the rate of change of the demanded speed signal as a function of the stall factor.
Claim 2
Dependent Claim
181 words
A fuel control system for a gas turbine engine comprising: means for generating an actual speed signal proportional to the actual turbine speed of the gas turbine engine; means for generating a scheduled speed signal proportional to a desired output power; means for generating a demanded speed signal proportional to the time integral of a difference signal; means for generating said difference signal proportional to the difference between said scheduled speed signal and said demanded speed signal; means for generating an error signal proportional to the difference between said demanded speed signal and said actual speed signal; means for controlling the fuel flow to the gas turbine engine as a function of said error signal; means for generating a stall factor as a function of the difference between the rate of change of the demanded speed signal and the rate of change of the actual speed signal, said stall factor being indicative of the degree of stall the engine is experiencing; and means for modifying the rate of change of the demanded speed signal as a function of the stall factor.
Claim 3
Dependent Claim
68 words
A fuel control system as defined in claim 1 wherein said means for modifying the rate of change of the demanded speed signal includes: means for generating a stall acceleration term as a function of the stall factor; and means for selecting the lesser of the stall acceleration term and a demanded acceleration term and transmitting the lesser as the demanded acceleration to the demanded speed signal means.
Claim 4
Dependent Claim
46 words
A fuel control system as defined in claim 2, wherein: said stall acceleration term is a function of the degree of stall the engine is experiencing such that no modification is scheduled if the stall factor indicates that the engine is substantially on the acceleration schedule.
Claim 5
Dependent Claim
45 words
A fuel control system as defined in claim 3, wherein: said stall acceleration term is a function of the degree of stall the engine is experiencing such that a fractional modification is scheduled if the stall factor indicates the engine is off the acceleration schedule.
Claim 6
Dependent Claim
49 words
A fuel control system as defined in claim 4, wherein: said stall acceleration term is a function of the degree of stall the engine is experiencing such that a zero acceleration is scheduled if the stall factor indicates the engine is in danger of experiencing a mild surge condition.
Claim 7
Dependent Claim
48 words
A fuel control system as defined in claim 5, wherein: said stall acceleration term is a function of the degree of stall the engine is experiencing such that a deceleration is scheduled if the stall factor indicates the engine is in danger of experiencing a total surge condition.
Claim 8
Dependent Claim
38 words
A fuel control system as defined in claim 1, wherein: said means for modifyiong the rate of change of the demanded speed signal includes modifying said signal as a function of at least one other engine operating parameter.
Claim 9
Dependent Claim
22 words
A fuel control system as defined in claim 1, wherein said other engine operating parameter is actual engine speed corrected for temperature.
Claim 10
Dependent Claim
27 words
A fuel control system as defined in claim 8, wherein: said modification is proportional to the change in fuel/air ratio as a function of corrected engine speed.
Claim 11
Dependent Claim
27 words
A fuel control system as defined in claim 9, wherein: said modification is proportional to the change in the acceleration limit as function of corrected engine speed.
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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) | 1987-05-22 | 1987-11-21 | 1988-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-05-22 | 1991-11-21 | 1992-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-05-22 | 1995-11-21 | 1996-05-22 | $7700.00 | Window Closed / Lapsed |