US3750465A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Engine performance indicator
Assignee: Howell Instruments Inc
•
Filing: 1971-09-09
•
Granted: 1973-08-07
•
Expires: 1991-09-09
Abstract
Abstract A method and means for measuring changes in the quality of gas turbine engine performance, efficiency or engine trim by measuring at least a first engine parameter such as RPM, computing a second engine parameter value such as exhaust gas temperature (EGT) from the first measured parameter, also measuring the actual value of the second engine parameter and subsequently comparing the computer with the actual values (after possible correction factors have been taken into account) to indicate changes in engine performance or trim. The computed and actual values may also be integrated prior to comparison or a difference between the computed and actual values may first be taken and this difference subsequently integrated for comparison with a standard comparison value such as may be obtained by integrating one of the parameters or a time representative signal over the same timed interval. If the comparison takes the form of a ratio, the periods of integration may be chosen to insure that the denominator is an even power of ten such that the integral representing the numerator may be directly interpreted as a performance index. Simpler trim test equipment is also disclosed for measuring engine parameters such as EGT and RPM and automatically converting such measurements to standard day conditions before display to permit quick static or ground trim testing without requiring numerous hand calculations.
Inventors
- 👤 J Howell
- 👤 R Rowan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 13:00
CPC Classifications
G; G07; G07C; G07C3/00
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
112 words
A trim tester for measuring the performance quality of a gas turbine engine, said trim tester comprising: transducer means for providing an electrical signal proportional to an engine operating parameter, ambient parameter adjustment means for providing an electrical signal related to an ambient environmental condition, and computation and display means connected to both said transducer means and to said ambient parameter adjustment means for automatically computing a normalized value for said engine operating parameter corresponding to standard day conditions with the applicable correction factor being obtained from said ambient environmental condition and for displaying said normalized value to permit direct comparison with predetermined normalized value ranges as an indication of engine trim.
Claim 2
Dependent Claim
112 words
A trim tester for measuring the performance quality of a gas turbine engine, said trim tester comprising: transducer means for providing an electrical signal proportional to an engine operating parameter, ambient parameter adjustment means for providing an electrical signal related to an ambient environmental condition, and computation and display means connected to both said transducer means and to said ambient parameter adjustment means for automatically computing a normalized value for said engine operating parameter corresponding to standard day conditions with the applicable correction factor being obtained from said ambient environmental condition and for displaying said normalized value to permit direct comparison with predetermined normalized value ranges as an indication of engine trim.
Claim 3
Dependent Claim
84 words
A trim tester as in claim 1 wherein: said transducer means comprises a thermo-couPle means for measuring actual engine exhaust gas temperature EGTA and said ambient environmental condition is temperature, said ambient parameter adjustment means comprises a variable impedance for controlling an electrical signal in proportion to the ambient temperature and therefore in proportion to theta , where theta is total air temperature divided by 519, and said computation and display means includes means for computing and displaying the value of EGTA/ theta .
Claim 4
Dependent Claim
37 words
A trim tester as in claim 2 wherein said thermocouple means includes means for correcting the raw output signal of thermocouple devices to the actual EGTA, the correction factors being a function of theta or ambient temperature.
Claim 5
Dependent Claim
56 words
A trim tester as in claim 3 wherein said means for correcting comprises a differential amplifier having one input connected to receive an uncorrected EGT voltage from a thermocouple transducer and another differential input connected to said ambient parameter adjustment means whereby the differential input receives a correction voltage which is a function of theta .
Claim 6
Dependent Claim
98 words
A trim tester as in claim 1 wherein: said transducer means comprises means for measuring actual engine speed RPMA and said embient environmental condition is temperature, said ambient parameter adjustment means comprises a variable impedance for controlling a first electrical signal in proportion to ambient temperature and means for utilizing said first electrical signal to produce a second electrical signal approximately proportional to the square root of theta , where theta is total air temperature divided by 519, and said computation and display means includes means for computing and displaying the value of RPMA/ Square Root theta .
Claim 7
Dependent Claim
153 words
A trim tester as in claim 1 including further transducer means and further computation and display means, and wherein the first mentioned transducer means comprises a thermocouple means for measuring actual engine exhaust gas temperature EGTA, said ambient parameter adjustment means comprises a variable impedance for controlling a first electrical signal in proportion to the ambient temperature and therefore in proportion to theta where theta is total air temperature divided by 519, the first mentioned computation and display means comprises means for computing and displaying the value of EGTA/ theta , said further transducer means comprises means for measuring actual engine speed RPMA, said ambient parameter adjustment means further comprising means for utilizing said first electrical signal to produce a second electrical signal approximately proportional to the square root of theta , and said further computation and display means includes means for computing and displaying the value of RPMA/ Square Root theta .
Claim 8
Dependent Claim
37 words
A trim tester as in claim 6 wherein said thermocouple means includes means for correcting the raw output signal of thermocouple devices to the actual EGTA, the correction factors being a function of theta or ambient temperature.
Claim 9
Dependent Claim
56 words
A trim tester as in claim 7 wherein said means for correcting comprises a differential amplifier having one input connected to receive an uncorrected EGT voltage from a thermocouple transducer and another differential input connected to said ambient parameter adjustment means whereby the differential input receives a correction voltage which is a function of theta .
Claim 10
Dependent Claim
164 words
A trim tester as in claim 6 wherein said first mentioned computation and display means and said further computation and display means each comprise a servo system including: a variable potentiometer connected to receive a voltage thereacross proportional to a desired denominator function, a differential summing means connected to a movable tap on said potentiometer and connected to receive a voltage proportional to a desired numerator function for providing an error voltage proportional to the difference between thE numerator function input and the voltage at said movable tap, motor means, driving means connected to said differential summing means and to said motor means for driving said motor from said error voltage, said motor being mechanically linked to drive said movable tap thereby completing a servo loop, and a counter also effectively linked to the motor for accumulating counts proportional to the movement of the movable tap whereby the counter contents is proportional to the ratio of said numerator function divided by said denominator function.
Claim 11
Dependent Claim
154 words
A trim tester as in claim 1 wherein said computation and display means comprises a servo system including: a variable potentiometer connected to receive a voltage thereacross proportional to a desired denominator function, a differential summing means connected to a movable tap on said potentiometer and connected to receive a voltage proportional to a desired numerator function for providing an error voltage proportional to the difference between the numerator function input and the voltage at said movable tap, motor means, driving means connected to said differential summing means and to said motor means for driving said motor from said error voltage, said motor being mechanically linked to drive said movable tap thereby completing a servo loop, and a counter also effectively linked to the motor for accumulating counts proportional to the movement of the movable tap whereby the counter contents is proportional to the ratio of said numerator function divided by said denominator function.
References Cited (Backward Citations)
US3272004A
Cited
US3538760A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-06 | 1977-02-05 | 1977-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-06 | 1981-02-05 | 1981-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-06 | 1985-02-05 | 1985-08-07 | $7700.00 | Window Closed / Lapsed |