US3839860A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic engine pressure ratio equalization system
Assignee: RTX Corp
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Filing: 1972-07-21
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Granted: 1974-10-08
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Expires: 1992-07-21
Abstract
Abstract An automatic engine pressure ratio equalization system for aircraft gas turbine engines is disclosed. The actual engine pressure ratio for each engine on the aircraft is compared to a reference, typically the engine pressure ratio of that engine having the maximum pressure ratio. Any difference therebetween is corrected by means of a trim motor on the engine fuel control in order to equalize the pressure ratio of all engines. A zero trim switch senses when each engine trim is at a minimum, and logic circuitry is used to reduce all trims concurrently whenever none of the trims are at the minimum to thereby prevent escalation of all engine trims to the upper authority limit of the fuel control trimmer.
Inventors
- 👤 A Martin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 11:41
CPC Classifications
F; F02; F02C; F02C9/00; F02C9/26; F02C9/42; Y; Y02; Y02T; Y02T50/00; Y02T50/60
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
279 words
A pressure ratio equalization system for maintaining each of a plurality of turbine engines at the same engine pressure ratio, each of said engines having a fuel control associated therewith for regulating the flow of fuel to said engines in response to a control signal, comprising limited authority fuel trimming means connected in the fuel flow line between each said fuel control and said engine for further regulating the flow of fuel to said engines, switch means connected with each of said fuel trimming means, said switch means producing a limit signal when the fuel trimming means to which it is connected is at its lower limit wherein minimum fuel flow occurs therethrough, means for measuring the pressure ratio across each engine and producing a pressure ratio signal indicative thereof, selector means receiving each of said pressure ratio signals and selecting therefrom the maximum of said pressure ratio signals, means for comparing the pressure ratio signal from each engine with the maximum pressure ratio signal to produce therefrom a pressure ratio error signal for each engine, means responsive to said pressure ratio error signal for varying the limited authority fuel trimming means for its respective engine in a direction to increase the fuel flow therethrough and null said error signal, circuit means receiving the limit signal from each of said switch means and producing an output signal upon the absence of limit signals from all of said switch means, and means responsive to said output signal for varying the limited authority fuel trimming means in all said engines in a direction to reduce the fuel flow therethrough until one of said fuel trimming means is at its lower limit.
Claim 2
Dependent Claim
279 words
A pressure ratio equalization system for maintaining each of a plurality of turbine engines at the same engine pressure ratio, each of said engines having a fuel control associated therewith for regulating the flow of fuel to said engines in response to a control signal, comprising limited authority fuel trimming means connected in the fuel flow line between each said fuel control and said engine for further regulating the flow of fuel to said engines, switch means connected with each of said fuel trimming means, said switch means producing a limit signal when the fuel trimming means to which it is connected is at its lower limit wherein minimum fuel flow occurs therethrough, means for measuring the pressure ratio across each engine and producing a pressure ratio signal indicative thereof, selector means receiving each of said pressure ratio signals and selecting therefrom the maximum of said pressure ratio signals, means for comparing the pressure ratio signal from each engine with the maximum pressure ratio signal to produce therefrom a pressure ratio error signal for each engine, means responsive to said pressure ratio error signal for varying the limited authority fuel trimming means for its respective engine in a direction to increase the fuel flow therethrough and null said error signal, circuit means receiving the limit signal from each of said switch means and producing an output signal upon the absence of limit signals from all of said switch means, and means responsive to said output signal for varying the limited authority fuel trimming means in all said engines in a direction to reduce the fuel flow therethrough until one of said fuel trimming means is at its lower limit.
Claim 3
Dependent Claim
18 words
A pressure ratio equalization system as in claim 1 in which said circuit means is an AND circuit.
Claim 4
Dependent Claim
26 words
A pressure ratio equalization system as in claim 1 and including means for inhibiting said pressure ratio error signals upon the presence of said output signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-07 | 1978-04-08 | 1978-10-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-07 | 1982-04-08 | 1982-10-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-07 | 1986-04-08 | 1986-10-08 | $7700.00 | Window Closed / Lapsed |