US 11,009,520 B2Granted

Determination of machine rotational speed based on vibration spectral plots

AssigneeComputational Systems, Inc.

InventorsAnthony J. Hayzen, Stewart V. Bowers, III

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Abstract

An apparatus is described that determines an estimated rotational speed of a rotating component of a machine in the absence of a reliable tachometer signal to indicate an actual rotational speed. The apparatus includes a processor that produces a spectral plot of the vibrational data, locates peaks in the spectral plot, and scans the spectral plot in predetermined rotational speed increments to provide candidate rotational speeds. For each candidate rotational speed, associated harmonics are identified, closest peaks in the spectral plot to the candidate rotational speed and its harmonics are located, gaps between the closest peaks and the candidate rotational speed and its harmonics are measured, and a sum of the gaps is recorded. The estimated rotational speed is the candidate rotational speed associated with a minimum sum of the gaps.

Claims14

Dependent claims

An apparatus for determining an estimated rotational speed of a rotating component of a machine in the absence of a reliable tachometer signal to indicate an actual rotational speed, the apparatus comprising:

a vibration sensor attached to the machine that generates an analog vibration signal indicative of vibration of the machine;
an analog-to-digital converter in electrical communication with the vibration sensor that converts the analog vibration signal to digital vibration data;
an input device that receives input information from a user, the input information including a nominal speed value indicating a nominal rotational speed associated with the machine;
a processor in electrical communication with the analog-to-digital converter and the input device that executes instructions to process the digital vibration data, including instructions to:
(1) receive the nominal speed value from the input device;
(2) generate a vibration spectrum based on the digital vibration data, the vibration spectrum comprising vibration amplitude values associated with frequency values;
(3) identify a plurality of vibration peaks in the vibration spectrum, each of the vibration peaks having a peak amplitude value and a peak frequency value associated therewith;
for j=1 to J:
(4) determine a jth set of frequency values comprising:
a jth candidate frequency value related to the nominal speed value;
and
a plurality of jth harmonic frequency values that are greater than the jth candidate frequency value and distributed incrementally across the vibration spectrum;
(5) for each candidate and harmonic frequency value in the jth set, determine one of the vibration peaks identified in step (3) having a peak frequency value that is closest to the candidate or harmonic frequency value;
(6) for each candidate and harmonic frequency value in the jth set, determine a frequency difference value indicating a difference between the candidate or harmonic frequency value and the peak frequency value that is closest;
(7) generate a jth sum of the frequency difference values corresponding to the jth set of frequency values, and associate the jai sum with the candidate frequency value of the jth set of frequency values;
(8) increment j by one and repeat steps (4) through (8) until j equals J;
(9) determine a minimum sum of the J number of sums of the frequency difference values;
(10) determine the estimated rotational speed of the machine based on the candidate frequency value associated with the minimum sum;
and
(11) analyze the digital vibration data using the estimated rotational speed of the machine to determine an operational characteristic of the machine.

17 more elements

a vibration sensor attached to the machine that generates an analog vibration signal indicative of vibration of the machine;
an analog-to-digital converter in electrical communication with the vibration sensor that converts the analog vibration signal to digital vibration data;
an input device that receives input information from a user, the input information including a percent accuracy value (% Accuracy) and a start frequency value (StartFreq) indicating a nominal rotational speed associated with the machine;
a processor in electrical communication with the analog-to-digital converter and the input device that executes instructions to process the digital vibration data, including instructions to:
(1) receive the percent accuracy value and the start frequency value from the input device;
(2) generate a vibration spectrum based on the digital vibration data, the vibration spectrum comprising vibration amplitude values associated with frequency values;
(3) identify K number of vibration peaks in the vibration spectrum, each of the vibration peaks having a peak amplitude value (AmplLocPeak(k)) and a peak frequency value (FreqLocPeak(k)) associated therewith;
(4) for each of N number of harmonics of the start frequency value, determine candidate frequency values (FreqCandidate(j)) for which the following relationship is true:
|FreqLocPeak(k)−(n×StartFreq)|≤% Accuracy
(5) for each of the candidate frequency values determined in step (4), determine a percentage difference value (PctDiff) according to:
PctDiff
=
[
FreqLocPeak
⁢
⁢
(
k
)
-
n
×
(
FreqCandidate
⁢
⁢
(
j
)
)
]
n
×
(
FreqCandidate
⁢
⁢
(
j
)
)
and a score value according to:
score value=1−PctDiff
(6) for each harmonic family of the vibration peaks located in step (3), deter mine a total score, which is a sum of all score values determined in step (5);
(7) determine the estimated rotational speed of the machine based on the candidate frequency value associated with the harmonic family having a largest total score;
and
(8) analyze the digital vibration data using the estimated rotational speed of the machine to determine an operational characteristic of the machine.

44 more elements

a vibration sensor attached to the machine that generates an analog vibration signal indicative of vibration of the machine;
an analog-to-digital converter in electrical communication with the vibration sensor that converts the analog vibration signal to digital vibration data;
an input device that receives input information from a user, the input information including a percent accuracy value and a start frequency value indicating a nominal rotational speed associated with the machine;
a processor in electrical communication with the analog-to-digital converter and the input device that executes instructions to process the digital vibration data, including instructions to:
(1) generate a vibration spectrum based on the digital vibration data, the vibration spectrum comprising vibration amplitude values associated with frequency values;
(2) identify a plurality of vibration peaks in the vibration spectrum, each having a peak amplitude value and a peak frequency value;
(3) determine a plurality of candidate frequency values within the vibration spectrum that corresponds to harmonics of the start frequency value, wherein each candidate frequency value is within the percent accuracy value of at least one of the plurality of vibration peaks;
(4) determine a plurality of scores based on differences between the peak frequency values of the plurality of vibration peaks identified in step (2) and the candidate frequency values determined in step (3);
(5) determine the estimated rotational speed of the machine based on a candidate frequency value that is associated with one of the harmonic families having a particular score;
and
(6) analyze the digital vibration data using the estimated rotational speed of the machine to determine an operational characteristic of the machine.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/269,156Filed 6 Feb 2019 · continuation in part
Priority: 5 Apr 2018
Published: US 2019/0310280 A110 Oct 2019
Granted: 18 May 2021
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G01P 3/489
Of pulse signals: digital circuits therefor
G01H 1/003
Measuring characteristics of vibrations in solids by using direct conduction to the detector: of rotating machines
G01P 1/122
Recording devices: speed recorders
G01P 3/48
For measuring angular speed: by measuring frequency of generated current or voltage

Family

Application15/946,403Parent of this continuation-in-part · filed 5 Apr 2018
US 2019/0310281 A1Pre-grant publication · published 10 Oct 2019
US 10,823,749 B2Parent of this continuation-in-part
US 2019/0310280 A1Published application
US 11,009,520 B2This patent

From the US filing history. Foreign family members aren’t listed.