Data processing: measuring – calibrating – or testing – Measurement system – Statistical measurement
Reexamination Certificate
2001-12-04
2004-03-23
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Statistical measurement
C702S179000, C702S180000, C702S182000, C702S183000
Reexamination Certificate
active
06711523
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This application relates to the field of vibration analysis and more particularly to performing vibration analysis for the purpose of device monitoring.
2. Description of Related Art
The transmission of power to rotors which propel helicopters and other shafts that propel devices within the aircraft induce vibrations in the supporting structure. The vibrations occur at frequencies that correspond to the shaft rotation rate, mesh rate, bearing passing frequency, and harmonics thereof. The vibration is associated with transmission error (TE). Increased levels of TE are associated with transmission failure. Similar types of vibrations are produced by transmissions in fixed installations as well.
Parts, such as those that may be included in a helicopter transmission, may be replaced in accordance with a predetermined maintenance and parts replacement schedule. These schedules provide for replacement of parts prior to failure. The replacement schedules may indicate replacement time intervals that are too aggressive resulting in needless replacement of working parts. This may result in incurring unnecessary costs as airplane parts are expensive. Additionally, new equipment may have installed faulty or defective parts that may fail prematurely.
Thus it may be desirable to provide for an efficient technique for detecting part and device degradation without unnecessarily replacing parts. It may be desirable that this technique also provide for problem determination and detection prior to failure.
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention are a method executed in a computer system and computer program product for determining a condition indicator about a characteristic of a component. A distribution of observed data associated with said component is determined. A difference between said distribution and a normal distribution is determined. The condition indicator is determined using the difference.
In accordance with another aspect of the invention are a method executed in a computer system and computer program product for determining a condition indicator associated with a component. A total impulse signal is determined in accordance with configuration data. The total impulse signal is a superposition of gear and bearing noise represented as a convolution of a gear and bearing signal with a gearbox transfer function. A condition indicator is determined in accordance with the total impulse signal.
In accordance with yet another aspect of the invention is a method executed in a computer system and a computer program product for determining a health status of a component using at least one condition indicator. At least one condition indicator is determined using at least one of: an impulse determination technique and a statistical normality test. The health indicator is determined in accordance with the at least one indicator.
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Smith, J. Derek, Marcel Dekker, Inc., “Causes of Noise”, Gear Noise and Vibration, 3-63, 1999.
Hochman, et al., “Mechanics of Gear Tooth Crack Signals and their Detection in Application for a Helicopter Health Usage and Management System (HUMS)”, Goodrich Company, Jan. 12, 2002.
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Mitchell, John, Introduction to Machinery Analysis and Monitoring 2ndEdition, “Analyzing Machine Condition-General Characteristics”, Pennwell Books, 1993, pp. 171-255.
Bechhoefer Eric Robert
Hochmann David
Choate Hall & Stewart
Hoff Marc S.
Simmonds Precision Products Inc.
Suarez Felix
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