Vibration diagnosing method and apparatus for a rotary machine

• US 4,435,770 A
• Filed: 03/19/1981
• Issued: 03/06/1984
• Est. Priority Date: 03/19/1980
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sato, Kazuo, Ohmori, Motoji, Takasumi, Masakazu, Shiga, Motohiro, Shiohata, Koki, Fujisawa, Fumio
• Primary Examiner(s): Wise, Edward J.
• Application Number:
  US06/245,517
• Time in Patent Office: 1,083 Days
• Field of Search: 364/508, 364/494, 73/462, 73/579, 73/593
• US Class Current: 702/56
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence
• CPC Class Codes: G01M 1/34 by removing material from the body to be tested, e.g. from the tread of tyres

Abstract

A method and apparatus for diagnosing a vibration in a rotor of the rotary machine including detecting the number of rotations and the vibration in the rotor when the rotor is rotating, extracting a vibration component synchronized with the number of rotations, determining whether the vibration component is normal or abnormal, calculating an abnormal vibration component through a vector operation by using the detected vibration component and a previously determined rotor vibration component in a normal state of the rotor, when the detected vibration component is judged to be abnormal, normalizing a vibration pattern of the abnormal vibration component, and determining an unbalance originating position in the rotor, which generates the abnormal vibration, by using a comparison of the normalized abnormal vibration pattern with a normalized vibration pattern of a previously determined unbalanced vibration.

Claims

1. An apparatus for diagnosing a vibration in a rotor of a rotary machine comprising:

means for sensing the number of rotations of the rotor and providing an output indicative thereof;

vibration detecting means for detecting vibration at a plurality of measuring points disposed at intervals along a direction of the rotor shaft when the rotor is rotating and providing outputs representative thereof;

vibration analyzer means responsive to the outputs of the vibration detector means and the rotation sensor means for extracting vibration components synchronized with the number of rotations of the rotor at the plurality of measuring points;

comparing means for comparing the extracted vibration components with reference values therefor corresponding to normal vibration of the rotor for determining that the detected vibration is abnormal when at least one of the extracted vibration components exceeds the corresponding one of the reference values therefor and that the detected vibration is normal when all of the extracted vibration components do not exceed the corresponding reference value therefor, the comparing means providing an output of the extracted vibration components when the detected vibration is abnormal;

calculating means for calculating abnormal vibration components in accordance with the output of the extracted vibration components and predetermined values representative of respective rotor vibration components in a normal state of the rotor and providing an output of abnormal vibration components; and

pattern comparing means for comparing a pattern of amplitude values of the abnormal vibration components with patterns of previously determined vibration amplitude values at the respective measuring points when an unbalance is provided at different positions of the rotor for determining an unbalance originating position in the rotor according to a selected one of the predetermined unbalanced vibration patterns which is the most similar to the abnormal vibration pattern.

2. An apparatus according to claim 1, further comprising memory means for storing the predetermined values representative of respective rotor vibration components in the normal state of the rotor, the calculating means for calculating the abnormal vibration components including first arithmetic means for obtaining the abnormal vibration components, second arithmetic means for determining which one of the plurality of abnormal vibration components has a maximum amplitude, and third arithmetic means for normalizing the abnormal vibration components on the basis of the one of the abnormal vibration components having the maximum amplitude.

3. An apparatus according to claim 2, further comprising pattern memory means for storing the patterns of previously determined vibration amplitude values at the respective measuring points when an unbalance is provided at different positions of the rotor, the stored patterns having the amplitude values thereof normalized in accordance with the maximum amplitude value.

4. An apparatus according to claim 3, wherein the first arithmetic means includes means for subtracting the stored predetermined values representative of respective rotor vibration components in the normal state of the rotor from the corresponding extracted vibration components so as to obtain the abnormal vibration components.

5. A method for diagnosing a vibration in a rotor of a rotary machine comprising the steps of:

detecting the number of rotations and the vibration in the rotor at a plurality of measuring points disposed at intervals along a direction of the rotor shaft when the rotor is rotating and providing signals representative thereof;

extracting vibration components synchronized with the number of rotations of the rotor from the signals representative of the detected vibration of the rotor at the plurality of measuring points;

comparing the extracted vibration components with reference values therefor corresponding to normal vibration in the rotor of the rotary machine for determining that the detected vibration is abnormal when at least one of the extracted vibration components exceeds the corresponding one of the reference values therefor and that the detected vibration is normal when all of the extracted vibration components do not exceed the corresponding reference values therefor;

calculating abnormal vibration components upon determining that the detected vibration is abnormal by subtracting predetermined values representative of respective rotor vibration components in a normal state of the rotor from the corresponding extracted vibration components so as to obtain abnormal vibration components; and

comparing a pattern of amplitude values of the abnormal vibration components with patterns of previously determined vibration amplitude values at the respective measuring points when an unbalance is provided at different positions of the rotor for determining an unbalance originating position in the rotor according to a selected one of the predetermined unbalanced vibration patterns which is the most similar to the abnormal vibration pattern.

6. A method according to claim 5, wherein the step of calculating abnormal vibration components includes performing the subracting in accordance with a vector operation.

7. A method according to claim 5, wherein the step of calculating abnormal vibration components includes normalizing the abnormal vibration components by setting the maximum value of the abnormal vibration components to one and setting the other values of the abnormal vibration components in accordance therewith.

8. A method according to claim 7, wherein the step of normalizing the abnormal vibration components includes setting the maximum amplitude value of the abnormal vibration components to one and setting the other amplitude values of the abnormal vibration components in accordance therewith.

9. A method according to claim 8, wherein the previously determined unbalanced vibration values are values normalized by setting the maximum value to one and setting the other values in accordance therewith, and the step of comparing to determine the unbalanced originating position includes selecting one of the predetermined unbalanced vibration patterns as the most similar pattern in accordance with a minimum one of a square sum value of differences between respective amplitudes of the abnormal vibration components and the corresponding amplitudes of the previously determined unbalanced vibration patterns.

10. A method according to claim 7, wherein the previously determined unbalanced vibration values are values normalized by setting the maximum value to one and setting the other values in accordance therewith, and the step of comparing to determine the unbalanced originating position includes selecting one of the predetermined unbalanced vibration patterns as the most similar pattern in accordance with the minimum one of a root mean square value of differences between respective amplitudes of the abnormal vibration components and the corresponding amplitudes of the previously determined unbalanced vibration patterns.

11. A method according to claim 5, further comprising the step of calculating the unbalanced quantity at the unbalanced originating position in accordance with the abnormal vibration components and the previously determined unbalanced vibration amplitudes.

12. A method according to claim 11, wherein the step of calculating the unbalanced quantity includes utilizing influence coefficients of the previously determined unbalanced vibration values.

13. A vibration diagnosing apparatus for rotary machine for diagnosting a vibration in a rotor of the rotary machine by detecting the number of rotations and the vibration in the rotor when the rotor is rotating, comprising:

a rotation sensor for sensing the number of rotations of the rotor;

a vibration detector for detecting a vibration generated in the rotor at a proper position of the rotor;

a vibration analyzer for extracting an unbalance vibration component synchronized with the number of rotations by using a vibration signal from said vibration detector and a phase reference signal obtained from said rotation sensor;

judging means for judging whether said unbalance vibration component is normal or abnormal by comparing an unbalance vibration component derived from said vibration analyzer with a reference value;

memory means for previously storing a rotor vibration component in a normal state;

first arithmetic means for extracting an abnormal vibration component on the basis of an abnormal unbalance vibration component derived from said judging means and a normal vibration component stored in and derived from said memory means;

second arithmetic means for specifying a maximum amplitude of an abnormal vibration component from said first arithmetic means;

third arithmetic means for normalizing said abnormal vibration component on the basis of the maximum amplitude of the abnormal vibration component derived from said second arithmetic means;

pattern memory means for previously storing the normalized pattern of the unbalance vibration;

unbalance originating position identifying means for identifying a position in the rotor where the unbalanced vibration causing the abnormal vibration is generated on the basis of the comparison of the normalized abnormal vibration pattern from said third arithmetic means with the normalized unbalanced vibration pattern from said pattern memory means.

14. A vibrating diagnosing apparatus according to claim 13, further comprising a fourth arithmetic means for calculating a quantity of the abnormal vibration generated at said unbalance position by using the abnormal vibration component derived from said first arithmetic means and influence component from said pattern memory means.