Method and apparatus for calculating the amplitude of a complex waveform associated with a rotating machine shaft after removing the running speed frequency
First Claim
1. A method for calculating the amplitude of a waveform associated with a rotating machine shaft after removing the fundamental frequency thereof comprising:
- a) storing a predetermined percentage of samples of said waveform obtained at a predetermined sampling rate in a bin of data in a memory;
b) associating a speed of said shaft with each of said stored samples;
c) determining the center frequency of a bandstop filter through which said samples stored in said memory data bin are passed by averaging the speed of said shaft associated with each of said stored samples;
d) accumulating a predetermined number of said stored samples starting with the first of said stored samples; and
e) using said accumulated stored samples to provide a data point that is free of any residual bias in said samples.
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Accused Products
Abstract
A sampled data system for computing the amplitude of a singal received from a vibration sensing probe minus the fundamental frequency associated with the running speed of a rotating machinery shaft. This signal is known as the Not 1X waveform and variations in its amplitude can signal problems with bearings, rotors, cracks or mechanical looseness, and/or fluids of the rotating machine. The amplitude of the Not 1X waveform can be provided in either peak to peak amplitude, peak amplitude, absolute average or root mean square.
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Citations
16 Claims
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1. A method for calculating the amplitude of a waveform associated with a rotating machine shaft after removing the fundamental frequency thereof comprising:
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a) storing a predetermined percentage of samples of said waveform obtained at a predetermined sampling rate in a bin of data in a memory;
b) associating a speed of said shaft with each of said stored samples;
c) determining the center frequency of a bandstop filter through which said samples stored in said memory data bin are passed by averaging the speed of said shaft associated with each of said stored samples;
d) accumulating a predetermined number of said stored samples starting with the first of said stored samples; and
e) using said accumulated stored samples to provide a data point that is free of any residual bias in said samples. - View Dependent Claims (2, 3)
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4. A method for calculating the amplitude of a waveform associated with a rotating machine shaft after removing the fundamental frequency thereof comprising:
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a) storing a predetermined percentage of samples of said waveform obtained at a predetermined sampling rate in a bin of data in a memory;
b) associating a speed of said shaft with each of said stored samples;
c) determining the center frequency of a bandstop filter through which said samples stored in said memory data bin are passed by averaging the speed of said shaft associated with each of said stored samples;
d) accumulating a predetermined number of said stored samples starting with the first of said stored samples; and
e) calculating the average of said accumulated stored samples. - View Dependent Claims (5, 6)
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7. A method for calculating the amplitude of a waveform associated with a rotating machine shaft after removing the fundamental frequency thereof comprising:
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a) sampling said waveform at a predetermined sampling rate;
b) storing a predetermined percentage of said samples in a bin of data in a memory;
c) associating a speed of said shaft with each of said stored samples;
d) passing said samples stored in said memory data bin through a bandstop filter;
e) determining the center frequency of said filter by averaging the speed of said shaft associated with each of said stored samples;
f) accumulating a predetermined number of said stored samples starting with the first of said stored samples; and
g) calculating the average of said accumulated stored samples. - View Dependent Claims (8, 9, 10, 11)
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12. A method for calculating the amplitude of a waveform associated with a rotating machine shaft after removing the fundamental frequency thereof comprising:
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a) storing a predetermined percentage of samples of said waveform obtained at a predetermined sampling rate in a bin of data in a memory;
b) associating a speed of said shaft with each of said stored samples;
c) determining the center frequency of a bandstop filter through which said samples stored in said memory data bin are passed by averaging the speed of said shaft associated with each of said stored samples;
d) accumulating in an accumulator a predetermined number of said stored samples starting with the first of said stored samples;
e) using said accumulated stored samples to provide a data point that is free of any residual bias in said samples;
f) storing said accumulated value when said accumulated value is close to overflow; and
g) setting said accumulator to zero. - View Dependent Claims (13, 14)
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15. A system for calculating the amplitude of a waveform associated with a rotating machine shaft after removing the fundamental frequency thereof comprising:
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a) means for storing a predetermined percentage of samples of said waveform obtained at a predetermined sampling rate in a bin of data in a memory;
b) means for associating a speed of said shaft with each of said stored samples;
c) means for determining the center frequency of a bandstop filter through which said samples stored in said memory data bin are passed by averaging the speed of said shaft associated with each of said stored samples;
d) means for accumulating a predetermined number of said stored samples starting with the first of said stored samples; and
e) means for using said accumulated stored samples to provide a data point that is free of any residual bias in said samples.
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16. A system for calculating the amplitude of a waveform associated with a rotating machine shaft after removing the fundamental frequency thereof comprising:
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a) a bin of data in a memory to store a predetermined percentage of samples of said waveform obtained at a predetermined sampling rate; and
b) a computing device operative to;
(i) associate a speed of said shaft with each of said stored samples;
(ii) determine the center frequency of a bandstop filter through which said samples stored in said memory data bin are passed by averaging the speed of said shaft associated with each of said stored samples;
(iii) accumulate a predetermined number of said stored samples starting with the first of said stored samples; and
(iv) use said accumulated stored samples to provide a data point that is free of any residual bias in said samples.
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Specification