US3584507A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Engine usage indicator
Assignee: Avco Corp
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Filing: 1970-03-06
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Granted: 1971-06-15
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Expires: 1990-03-06
Abstract
Abstract Intervals between overhaul are determined by continuously measuring power turbine temperature and shaft speed and by converting the collected data into numbers of pulses proportional to creep, low cycle fatigue, and temperature shock fatigue. The number of pulses is then summed in digital counters. The total number of pulses due to creep, low cycle fatigue, and temperature shock fatigue are used as a measure of the exhausted life of the engine.
Inventors
- 👤 Rudolph Hohenberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:29
CPC Classifications
G; G01; G01M; G01M15/00; G01K; G01K3/00; G01K3/02; G01K3/04; G01M15/04; G01M15/05; G07; G07C; G07C3/00
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
330 words
In a system for determining the exhausted life of a gas turbine engine, said system including means for generating a first signal proportional to engine temperature and a second signal proportional to shaft speed of said engine, the combination comprising: a first function generator, said first and second signals being applied to said first function generator, said first function generator having an output signal approximately proportional to the exhausted life of said engine due to creep, said exhausted life due to creep being a first function of engine temperature and speed; a frequency converter for converting said output signal to first pulses having a repetition rate proportional to the magnitude of said output signal; first digital means for summing the number of said pulses, the summation of said pulses representing the exhausted life of said engine due to creep; a second function generator, said first and second signals being applied to said second function generator, said second function generator having an output signal approximately proportional to the exhausted life of said engine due to low cycle fatigue, said exhausted life due to low cycle fatigue being a second function of engine temperature and speed; second digital summing means for summing the approximate magnitude of the output of said second function generator when the output of said second function generator is increasing, said summation representing the exhausted life of said engine due to low cycle fatigue; additional function generator means, said first signal being applied to said additional function generator means, said additional function generator means having an output signal approximately proportional to the exhausted life of said engine due to temperature shock, said exhausted life due to shock being a function of the rate of change of temperature; and third digital summing means for summing the magnitude of the output of said additional function generator means when the output signal from said function generator is increasing, said summation approximately representing the exhausted life of said engine due to temperature shock.
Claim 2
Dependent Claim
330 words
In a system for determining the exhausted life of a gas turbine engine, said system including means for generating a first signal proportional to engine temperature and a second signal proportional to shaft speed of said engine, the combination comprising: a first function generator, said first and second signals being applied to said first function generator, said first function generator having an output signal approximately proportional to the exhausted life of said engine due to creep, said exhausted life due to creep being a first function of engine temperature and speed; a frequency converter for converting said output signal to first pulses having a repetition rate proportional to the magnitude of said output signal; first digital means for summing the number of said pulses, the summation of said pulses representing the exhausted life of said engine due to creep; a second function generator, said first and second signals being applied to said second function generator, said second function generator having an output signal approximately proportional to the exhausted life of said engine due to low cycle fatigue, said exhausted life due to low cycle fatigue being a second function of engine temperature and speed; second digital summing means for summing the approximate magnitude of the output of said second function generator when the output of said second function generator is increasing, said summation representing the exhausted life of said engine due to low cycle fatigue; additional function generator means, said first signal being applied to said additional function generator means, said additional function generator means having an output signal approximately proportional to the exhausted life of said engine due to temperature shock, said exhausted life due to shock being a function of the rate of change of temperature; and third digital summing means for summing the magnitude of the output of said additional function generator means when the output signal from said function generator is increasing, said summation approximately representing the exhausted life of said engine due to temperature shock.
Claim 3
Dependent Claim
56 words
The invention as defined in claim 1 wherein the output signal from said first functIon generator is proportional to wherein the output signal from said second function generator is proportional to (e/B)Cn T7D, where n is said shaft speed, T7 is temperature, A,B,C,D and K are constants which are empirically determined, and e is natural e.
Claim 4
Dependent Claim
36 words
The invention as defined in claim 1 wherein said additional function generator means is a third function generator having an output signal approximately proportional to the rate of change of said temperature with respect to time.
Claim 5
Dependent Claim
210 words
The invention as defined in claim 3 wherein said third digital summing means comprises: first and second comparators, each of said comparators being supplied with the output signal of said third function generator and with a reference signal, said comparators each being a two-state device, said first comparator being in its first state when said output signal is less than said reference signal and being in its second state when said output signal is greater than said reference signal, said second comparator being in its first state when said output signal is less than said reference signal and being in its second state when said output signal is greater than said reference signal; means for counting the total number of changes of said first comparator from said first state to said second state, the total of said count representing an approximation of said exhausted life due to low cycle fatigue; and a reference signal generator for generating said reference signal, said generator having an initial output signal level, said reference signal generator including means for increasing and decreasing said reference signal level one unit for each change of said first and second comparators, respectively, from a first state to a second state, said unit being equal to said initial level.
Claim 6
Dependent Claim
73 words
The invention as defined in claim 4 wherein said reference signal generator comprises a digital pulse memory, said pulse memory being supplied with the output of each comparator, the digital output of said memory being equal to the difference between the numbers of pulses generated by said first and second comparators; and a digital-to-analog converter supplied with the digital output of said memory, the analog output of said converter being said reference signal.
Claim 7
Dependent Claim
130 words
The invention as defined in claim 1 wherein said additional function generator comprises a third function generator and a fourth function generator, said third function generator having an output which is approximately proportional to the rate of change of temperature with respect to time, said fourth function generator having an output which is approximately proportional to said temperature; and wherein said third digital means for summing the output of said additional function generator means includes an electronic switch, the increasing output of said fourth function generator being applied to said third digital means through said electronic switch, said switch passing the output of said fourth function generator to said third digital summing means only when the output of said third function generator in an increasing direction exceeds a predetermined level.
Claim 8
Dependent Claim
321 words
The invention as defined in claim 6 wherein said third digital summing means comprises: first and second comparators, each of said comparators being supplied with the output signal of said fourth function generator and with a reference signal, said comparators each being a two-state device, said first comparator being in its first state when said output signal is less than said reference signal and being in its second state when said output signal is greater than said reference signal, said second comparator being in its first state when said output signal is less than said reference signal and being in its second state when said output signal is greater than said reference signal; a variabLe reference signal generator for generating said reference signal, said generator having an initial output signal level, said reference signal generator including means for increasing and decreasing said reference signal level one unit for each change of said first and second comparators, respectively, from a first state to a second state, said unit being equal to said initial level; said means when said output of said third function generator exceeds said predetermined level for counting the total number of changes of said first comparator from said first state to said second state, the total of said count representing an approximation of said exhausted life due to low cycle fatigue including said electronic switch; and an additional up comparator, said up comparator being supplied with the output of said third function generator and a fixed reference signal, the output of said up comparator being in one state when the output of said third function generator is less than said fixed reference and being in a second state when said output is greater than said fixed reference output, said output being applied to said electronic switch, said electronic switch being open when said output is in said one state, and closed when said output is in said second state.
Claim 9
Dependent Claim
76 words
The invention as defined in claim 7 wherein said variable reference generator comprises a digital pulse memory, said digital pulse memory being supplied with the output of each comparator, the digital output of said memory being equal to the difference between the numbers of pulses generated by said first and second comparators; and a digital to analog converter supplied with the digital output of said memory, the analog output of said converter being said reference signal.
Claim 10
Dependent Claim
211 words
The invention as defined in claim 1 wherein said second digital summing means comprises: first and second comparators, each of said comparators being supplied with the output signal of said second function generator and with a reference signal, said comparators each being a two-state device, said first comparator being in its first state when said output signal is less than said reference signal and being in its second state when said output signal is greater than said reference signal, said second comparator being in its first state when said output signal is less than said reference signal and being in its second state when said output signal is greater than said reference signal; means for counting the total number of changes of said first comparator from said first state to said second state, the total of said count representing an approximation of said exhausted life due to the low cycle fatigue; and a reference signal generator for generating said reference signal, said generator having an initial output signal level, said reference signal generator including means for increasing and decreasing said reference signal level one unit for each change of said first and second comparators, respectively, from a first state to a second state, said unit being equal to said initial level.
Claim 11
Dependent Claim
75 words
The invention as defined in claim 9 wherein said reference signal generator comprises a digital pulse memory, said pulse memory being supplied with the output of each comparator, the digital output of said memory being equal to the difference between the numbers of pulses generated by said first and second comparators; and a digital to analog converter supplied with the digital output of said memory, the analog output of said converter being said reference signal.
Claim 12
Dependent Claim
279 words
In a system for determining the exhausted life of a gas turbine engine, said system including means for generating a first signal proportional to engine temperature and a second signal proportional to shaft speed of said engine, the combination comprising: a function generator, said first and second signals being applied to said function generator, said function generator having an output signal approximately proportional to the exhausted life of said engine due tO low cycle fatigue, said exhausted life being a function of said engine temperature and engine speed; first and second comparators, each of said comparators being supplied with the output signal of said function generator and with a reference signal, said comparators each being a two-state device, said first comparator being in its first state when said output signal is less than said reference signal and being in its second state when said output signal is greater than said reference signal, said second comparator being in its first state when said output signal is less than said reference signal and being in its second state when said output signal is greater than said reference signal; a reference signal generator for generating said reference signal, said generator having an initial output signal level, said reference signal generator including means for increasing and decreasing said reference signal level one unit for each change of said first and second comparators, respectively, from a first state to a second state, said unit being equal to said initial level; and digital means for summing the total number of changes of said first comparator from said first state to said second state, the summation of said changes representing an approximation of said exhausted life.
Claim 13
Dependent Claim
279 words
In a system for determining the exhausted life of a gas turbine engine, said system including means for generating a first signal proportional to engine temperature and a second signal proportional to shaft speed of said engine, the combination comprising: a function generator, said first and second signals being applied to said function generator, said function generator having an output signal approximately proportional to the exhausted life of said engine due tO low cycle fatigue, said exhausted life being a function of said engine temperature and engine speed; first and second comparators, each of said comparators being supplied with the output signal of said function generator and with a reference signal, said comparators each being a two-state device, said first comparator being in its first state when said output signal is less than said reference signal and being in its second state when said output signal is greater than said reference signal, said second comparator being in its first state when said output signal is less than said reference signal and being in its second state when said output signal is greater than said reference signal; a reference signal generator for generating said reference signal, said generator having an initial output signal level, said reference signal generator including means for increasing and decreasing said reference signal level one unit for each change of said first and second comparators, respectively, from a first state to a second state, said unit being equal to said initial level; and digital means for summing the total number of changes of said first comparator from said first state to said second state, the summation of said changes representing an approximation of said exhausted life.
Claim 14
Dependent Claim
43 words
The invention as defined in claim 11 wherein the output signal from said function generator is proportional to (e/B)Cn T7D, where n is said shaft speed, T7 is temperature, B,C and D are constants which are empirically determined, and e is natural e.
Claim 15
Dependent Claim
75 words
The invention as defined in claim 11 wherein said reference signal generator comprises a digital pulse memory, said pulse memory being supplied with the output of each comparator, the digital output of said memory being equal to the difference between the numbers of pulses generated by said first and second comparators; and a digital to analog converter supplied with the digital output of said memory, the analog output of said converter being said reference signal.
Claim 16
Dependent Claim
263 words
In a system for determining the exhausted life of a gas turbine engine, said system including means for generating a signal proportional to at least one engine operating parameter, the combination comprising: a function generator, said signal being applied to said function generator, said function generator having an output approximately proportional to the exhausted life of said engine due to fatigue, said exhausted life being a given function of said engine operating parameter; first and second comparators, each of said comparators being supplied with the output signal of said function generator and with a reference signal, said comparators each being a two-state device, said first comparator being in its first state when said output signal is less than said reference signal and being in its second state when said output signal is greater than said reference signal, said second comparator being in its first state when said output signal is less than said reference signal and being in its second state when said output signal is greater than said reference signal; a reference signal generator for generating said reference signal, said generator having an initial output level, said reference signal generator including means for increasing and decreasing said reference signal level one unit for each change of said first and second comparators, respectively, from a first state to a second state, said unit being equal to said initial level; and digital means for summing the total number of changes of said first comparator from said first state to said second state, the summation of said changes representing an approximation of said exhausted live.
Claim 17
Dependent Claim
263 words
In a system for determining the exhausted life of a gas turbine engine, said system including means for generating a signal proportional to at least one engine operating parameter, the combination comprising: a function generator, said signal being applied to said function generator, said function generator having an output approximately proportional to the exhausted life of said engine due to fatigue, said exhausted life being a given function of said engine operating parameter; first and second comparators, each of said comparators being supplied with the output signal of said function generator and with a reference signal, said comparators each being a two-state device, said first comparator being in its first state when said output signal is less than said reference signal and being in its second state when said output signal is greater than said reference signal, said second comparator being in its first state when said output signal is less than said reference signal and being in its second state when said output signal is greater than said reference signal; a reference signal generator for generating said reference signal, said generator having an initial output level, said reference signal generator including means for increasing and decreasing said reference signal level one unit for each change of said first and second comparators, respectively, from a first state to a second state, said unit being equal to said initial level; and digital means for summing the total number of changes of said first comparator from said first state to said second state, the summation of said changes representing an approximation of said exhausted live.
Claim 18
Dependent Claim
14 words
The invention as defined in claim 14 wherein said engine operating parameter is temperature.
Claim 19
Dependent Claim
26 words
The invention as defined in claim 14 wherein said one engine operating paraMeter is temperature and wherein a second engine operating parameter is engine shaft speed.
Claim 20
Dependent Claim
73 words
The invention as defined in claim 14 wherein said reference signal generator comprises a digital pulse memory, said pulse memory being supplied with the output of each comparator, the digital output of said memory being equal to the difference between the numbers of pulses generated by said first and second comparators; and a digital-to-analog converter supplied with the digital output of said memory, the analog output of said converter being said reference signal.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-06-14 | 1974-12-14 | 1975-06-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-14 | 1978-12-14 | 1979-06-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-14 | 1982-12-14 | 1983-06-15 | $7700.00 | Window Closed / Lapsed |