US3721088A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fuel control system for gas turbine engines
Assignee: ZF International UK Ltd
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Filing: 1971-04-21
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Granted: 1973-03-20
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Expires: 1991-04-21
Abstract
Abstract A fuel control system for a gas turbine engine supplied with fuel by a positive displacement pump has a flow control arrangement, a first spill valve connected across the pump and responsive to electrical signals dependent on engine operating conditions, and a second spill valve connected across the pump and responsive to the pressure drop across the flow control arrangement.
Inventors
- 👤 G Lewis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 05:42
CPC Classifications
F; F02; F02C; F02C9/00; F02C9/26; F02C9/32
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
150 words
A fuel control system for a gas turbine engine which is supplied, in use, with fuel by a positive displacement pump, comprises a first flow restrictor downstream of the pump, a pressurizing valve in series with the first flow restrictor on the downstream side thereof, a second flow restrictor connected in parallel across the series combination of the first flow restrictor and pressurizing valve, the said restrictors and pressurizing valve together forming a flow control arrangement, a first spill valve connected across the pump and responsive to an increase in pressure drop across the flow control arrangement to spill fuel to the upstream side of the pump, a second spill valve connected across the pump and the said first restrictor and responsive to an electrical signal to spill fuel to the upstream side of the pump and means for generating the said electrical signal in response to engine operating conditions.
Claim 2
Dependent Claim
150 words
A fuel control system for a gas turbine engine which is supplied, in use, with fuel by a positive displacement pump, comprises a first flow restrictor downstream of the pump, a pressurizing valve in series with the first flow restrictor on the downstream side thereof, a second flow restrictor connected in parallel across the series combination of the first flow restrictor and pressurizing valve, the said restrictors and pressurizing valve together forming a flow control arrangement, a first spill valve connected across the pump and responsive to an increase in pressure drop across the flow control arrangement to spill fuel to the upstream side of the pump, a second spill valve connected across the pump and the said first restrictor and responsive to an electrical signal to spill fuel to the upstream side of the pump and means for generating the said electrical signal in response to engine operating conditions.
Claim 3
Dependent Claim
27 words
A control system as claimed in claim 1 in which said second spill valve comprises a closure member and a torque motor responsive to said electrical signal.
Claim 4
Dependent Claim
88 words
A control system as claimed in claim 1 in wHich said signal generating means includes means for providing a first control signal dependent on the engine compressor speed and on the setting of a power demand control for the engine, means for providing a second control signal dependent on the combustion temperature of the engine and a first discriminating circuit whereby said electrical signal is dependent either on said first control signal or on a third control signal derived from said second control signal, whichever is the lower.
Claim 5
Dependent Claim
26 words
A control system as claimed in claim 3 which includes means for providing said third control signal when said second control signal exceeds a predetermined value.
Claim 6
Dependent Claim
49 words
A control system as claimed in claim 3 in which the means for providing said first control signal includes means for generating a signal proportional to the speed of the engine compressor and means for modifying said speed signal in accordance with the temperature at the engine compressor intake.
Claim 7
Dependent Claim
36 words
A control system as claimed in claim 5 which includes a second discriminating circuit whereby said first control signal is dependent either on said engine compressor speed or on said modified signal, whichever is the higher.
Claim 8
Dependent Claim
39 words
A control system as claimed in claim 6 which includes means for providing a fourth control signal which is dependent on the difference between the output of said second discriminating circuit and the setting of said powder demand control.
Claim 9
Dependent Claim
94 words
A control system as claimed in claim 3 in which the means for providing said second control signal comprises means for providing a fifth control signal dependent on the amount by which said combustion temperature exceeds a predetermined level, means for providing a sixth control signal dependent on the amount by which the ratio of said combustion temperature to the temperature at the engine compressor intake exceeds a predetermined level, and a third discriminating circuit whereby said second control signal is dependent on whichever of sad fifth and sixth control signals is the higher.
Claim 10
Dependent Claim
114 words
A control system as claimed in claim 8 for a gas turbine engine which includes a gas generator, a separate work turbine and a plurality of movable vanes by means of which the direction and quantity of gas flow to the work turbine may be varied, said control system further comprising an actuator for said vanes, first switching means operable to cause said actuator to increase said gas flow, and responsive to said second control signal when said combustion temperature exceeds a predetermined level, and second switching means operable to cause said actuator to decrease said gas flow, and responsive to said sixth control signal when said combustion temperature falls below a predetermined level.
Claim 11
Dependent Claim
52 words
A control system as claimed in claim 9 which includes means for routeing said fourth control signal to said first switching means, whereby said first switching means is responsive to said fourth control signal only when a signal from said power demand control exceeds an output signal from said second discriminating circuit.
Claim 12
Dependent Claim
59 words
A control system as claimed in claim 9 which includes means for routeing said fourth control signal to said actuator, whereby said actuator is responsive to said fourth control signal to tend to reduce said gas flow to the work turbine, only when an output signal from said second discriminating circuit exceeds a signal from said power demand circuit.
Claim 13
Dependent Claim
55 words
A control system as claimed in claim 9 which includes means for providing a seventh control signal dependent on the speed of the work turbine, said seventh control signal providing a further input for said first discriminating circuit, whereby said electrical signal is dependent on the lowest of said first, third or seventh control signals.
Claim 14
Dependent Claim
39 words
A control system as claimed in claim 12 in which said means for providing the seventh control signal includes means having an output dependent on the amount by which the speed of said work turbine exceeds a predetermined level.
Claim 15
Dependent Claim
43 words
A control systeM as claimed in claim 12 in which the actuating means for said vanes includes means responsive to servo pressure signals and first and second valves respectively responsive to said fourth and seventh control signals to vary said servo pressure signals.
References Cited (Backward Citations)
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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) | 1976-03-19 | 1976-09-18 | 1977-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-19 | 1980-09-18 | 1981-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-19 | 1984-09-18 | 1985-03-20 | $7700.00 | Window Closed / Lapsed |