APPARATUS FOR ANALYSING THE CONDITION OF A MACHINE HAVING A ROTATING PART

• US 20120296582A1
• Filed: 01/13/2011
• Published: 11/22/2012
• Est. Priority Date: 01/18/2010
• Status: Active Grant

• Current Assignee: S.P.M. Instrument AB
• Original Assignee: S.P.M. Instrument AB
• Inventors: Hedin, Lars-Olov
• Granted Patent: US 9,279,715 B2
• Time in Patent Office: Days
• US Class Current: 702/56
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence
• CPC Class Codes: G01M 13/045 Acoustic or vibration analysis

Abstract

A method of operating an apparatus for analysing the condition of a machine having a part rotating with a speed of rotation (f_ROT), includes:

• • receiving a first digital signal (S_RED, S_MD, S_ENV) dependent on mechanical vibrations emanating from rotation of the part;
  • analyzing the first digital signal (S_RED, S_MD, S_ENV) so as to detect peak amplitude values (Ap) during a finite time period (Pm), the finite time period corresponding to a certain amount (R) of revolution of the part; the certain amount of revolution corresponding to more than one revolution of the monitored rotatable part;
  • defining a plurality (N_R) of amplitude ranges;
  • sorting the detected peak amplitude values into corresponding amplitude ranges so as to reflect occurrence (N) of detected peak amplitude values within the plurality of amplitude ranges;
  • estimating a representative peak amplitude value (A_PR) in dependence on the sorted peak amplitude values and the certain amount (R).

Claims

1. A method of operating an apparatus for analysing the condition of a machine having a part rotating with a speed of rotation (f_ROT), comprising the steps of:

receiving a first digital signal (S_MD, S_R, S_F) dependent on mechanical vibrations emanating from rotation of said part;

analysing said first digital signal so as to detect peak amplitude values (Ap) during a finite time period (T_Pm), said finite time period corresponding to a certain amount (R) of revolution of said rotatable part;

said certain amount (R) of revolution corresponding to more than one revolution of said monitored rotatable part;

defining a plurality (N_R) of amplitude ranges;

sorting said detected peak amplitude values (Ap) into corresponding amplitude ranges so as to reflect occurrence (N) of detected peak amplitude values (Ap) within said plurality of amplitude ranges;

estimating a representative peak amplitude value (A_PR) in dependence on said sorted peak amplitude values (Ap) and said certain amount (R).

2. The method according to claim 1, further comprising

delivering said representative peak amplitude value (A_PR) to a user interface for presentation to a user.

3. The method according to claim 1, further comprising

performing a condition monitoring function (F1, F2, Fn) so as to analyse the condition of the machine dependent on said representative peak amplitude value (A_PR).

4. The method according to claim 1, wherein said estimation includes selecting the R:

th highest amplitude to be said representative peak amplitude value (A_PR).

5. The method according to claim 1, wherein said estimation includes the creation of an accumulative histogram.

6. The method according to claim 1, wherein the amplitude levels emanating from rotation of the monitored rotational part closely follow the normal distribution, also referred to as the Gaussian distribution;

and wherein

amplitude levels originating from plural revolutions of the rotational part are recorded in order to detect a relevant true peak value which is used for determination of the condition of the monitored rotational part.

7. The method according to claim 1, wherein

the estimation step includes estimating a not-so-frequent highest peak amplitude value (A_PR, 590) based on the nature of the Gaussian function or bell curve being such that an occurrence frequency of low amplitude values (550, 560) is informative about the amplitude of the not-so-frequent highest peak amplitude values (A_PR, 590).

8. The method according to claim 1, wherein

said certain amount of revolution includes at least n*R revolutions, wherein n is a number having a numerical value of at least one and R has a numerical value of at least 8.

9. The method according to claim 8, wherein

the numerical value of n is at least two;

and

the estimation step includes selecting the n;

th highest detected peak amplitude.

10. The method according to claim 8, wherein

the numerical value of R is at least 10.

11. The method according to claim 7, wherein

step of estimating a not-so-frequent highest peak amplitude value (A_PR, 590) uses detected peak amplitude values (Ap, r_g, r_h, 550) having an average occurrence frequency of one per revolution (g), and/or less than one per revolution (h) for estimating an amplitude value (A_PR, 590) for a peak having an average occurrence frequency of one per eight revolutions or less than one per eight revolutions (R);

wherein

said detected peak amplitude values (Ap, r_g, r_h, 550) being used for said estimation step have an average occurrence frequency of more than one per eight revolutions.

12. The method according to claim 11, wherein

said detected peak amplitude values (Ap, r_g, r_h, 550) being used for said estimation step have an average occurrence frequency of more than one per five revolutions.

13. The method according to claim 1, wherein

said analysis of said first digital signal includes a burst rejection step (S330, S340) which operates to deliver any detected peak values (A_P) at a delivery frequency of f_es, wherein

e*f_ROT, wherein

f_ROT is said speed of rotation, and

e is a factor having a value of ten or less than ten.

14. The method according to claim 13, wherein said burst rejection step (S330, S340) operates such that each peak amplitude value delivered by it reflects the highest amplitude value detected in the immediately preceding echo suppression period (T_es), said echo suppression period (T_es) being the inverse of said delivery frequency f_es.

15. A computer program for controlling the operation of an apparatus for analysing the condition of a machine having a part which is rotatable with a speed of rotation (f_ROT), the computer program comprising:

computer readable code means which, when run on an analysis apparatus, causes the computer to perform the steps of claim 1.

16. A computer program for controlling the operation of an apparatus for analysing the condition of a machine having a part which is rotatable with a speed of rotation (f_ROT), the computer program comprising:

computer readable code means which, when run on an analysis apparatus, causes the analysis apparatus to receive a first digital signal (S_MD, S_R, S_F) dependent on mechanical vibrations emanating from rotation of said part;

computer readable code means which, when run on an analysis apparatus, causes the analysis apparatus to detect peak amplitude values (Ap) during a finite time period (T_Pm), said finite time period corresponding to a certain amount (R) of revolution of said rotatable part;

said certain amount (R) of revolution corresponding to more than one revolution of said monitored rotatable part;

computer readable code means which, when run on an analysis apparatus, causes the analysis apparatus to sort said detected peak amplitude values (Ap) into a plurality (N_R) of corresponding amplitude ranges so as to reflect occurrence (N) of detected peak amplitude values (Ap) within said plurality of amplitude ranges;

computer readable code means which, when run on an analysis apparatus, causes the analysis apparatus to estimate a representative peak amplitude value (A_PR) in dependence on said sorted peak amplitude values (Ap) and said certain amount (R).

17. The computer program according to claim 16, wherein

said computer readable code means for causing the analysis apparatus to estimate a representative peak amplitude value (A_PR) includes computer readable code means for causing the analysis apparatus to select the R:

th highest amplitude to be said estimated representative peak amplitude value (A_PR), wherein R is said certain amount of revolution corresponding to more than one revolution of said monitored rotatable part.

18. The computer program according to claim 16, wherein

said certain amount of revolution includes at least n*R revolutions, wherein n is a number having a numerical value of at least one and R corresponds to plural revolutions.

19. The computer program according to claim 18, wherein

the numerical value of n is at least two;

and

said computer readable code means for causing the analysis apparatus to estimate a representative peak amplitude value (A_PR) includes computer readable code means for causing the analysis apparatus to select the n;

th highest detected peak amplitude to be said estimated representative peak amplitude value (A_PR).

20. The computer program according to claim 16, wherein

said computer readable code means for causing the analysis apparatus to estimate a representative peak amplitude value (A_PR) includes computer readable code means for causing the analysis apparatus to estimate an amplitude value (A_PR), which occurs on average substantially once per R revolutions, in dependence of detected amplitude levels (A_P) which on average occur more frequently than once per R revolutions, wherein R is said certain amount of revolution corresponding to more than one revolution of said monitored rotatable part.

21. An apparatus for analysing the condition of a machine having a part rotating with a speed of rotation (f_ROT), comprising:

means for receiving a first digital signal (S_RED, S_MD, S_ENV) dependent on mechanical vibrations emanating from rotation of said part;

means for analysing said first digital signal (S_RED, S_MD, S_ENV) so as to detect peak amplitude values (Ap) during a finite time period (Pm), said finite time period corresponding to a certain amount (R) of revolution of said rotatable part;

said certain amount (R) of revolution corresponding to more than one revolution of said monitored rotatable part;

means for sorting said detected peak amplitude values (Ap) into a plurality (N_R) of corresponding amplitude ranges so as to reflect occurrence (N) of detected peak amplitude values (Ap) within said plurality of amplitude ranges; and

means for estimating a representative peak amplitude value (A_PR) in dependence on said sorted peak amplitude values (Ap) and said certain amount (R).

22. The apparatus according to claim 21, further comprising

a user interface;

and

means for delivering said representative peak amplitude value (A_PR) to said user interface for presentation to a user.

23. The apparatus according to claim 21, further comprising

means for performing a condition monitoring function (F1, F2, Fn) so as to analyse the condition of the machine dependent on said representative peak amplitude value (A_PR).

24. The apparatus according to claim 21, wherein

said means for estimation includes means for selecting the R:

th highest amplitude to be said representative peak amplitude value (A_PR).

25. The apparatus according to claim 21, wherein

said means for estimation includes means for the creation of an accumulative histogram.

26. The apparatus according to claim 21, wherein

the amplitude levels emanating from rotation of the monitored rotational part closely follow the normal distribution;

and further comprising

means for recording amplitude levels originating from plural revolutions of the rotational part so as to detect a relevant true peak value indicative of the condition of the monitored rotational part.

27. The apparatus according to claim 21, wherein

said means for estimation includes means for estimating a not-so-frequent highest peak amplitude value (A_PR, 590) based on the nature of the Gaussian function or bell curve being such that an occurrence frequency of low amplitude values (550, 560) is informative about the amplitude of the not-so-frequent highest peak amplitude values (A_PR, 590).

28. The apparatus according to claim 21, wherein

said certain amount of revolution includes at least n*R revolutions, wherein n is a number having a numerical value of at least one and R corresponds to plural revolutions.

29. The apparatus according to claim 21, wherein

said certain amount of revolution includes at least n*R revolutions, wherein n is a number having a numerical value of at least one and R has a numerical value of at least 8.

30. The apparatus according to claim 28, wherein

the numerical value of n is at least two;

and

the means for estimation includes means for selecting the n;

th highest detected peak amplitude to be said representative peak amplitude value (A_PR).

31. The apparatus according to claim 28, wherein

the numerical value of R is at least 10.

32. The apparatus according to any preceding apparatus claim 21, wherein

said means for estimating a not-so-frequent highest peak amplitude value (A_PR, 590) is adapted to use detected peak amplitude values (Ap, r_g, r_h, 550) having an average occurrence frequency of one per revolution (g), and/or less than one per revolution (h) for estimating an amplitude value (A_PR, 590) for a peak having an average occurrence frequency of one per eight revolutions or less than one per eight revolutions (R);

wherein

said detected peak amplitude values (Ap, r_g, r_h, 550) being used for said estimation step have an average occurrence frequency of more than one per eight revolutions.

33. The apparatus according to claim 32, wherein

said detected peak amplitude values (Ap, r_g, r_h, 550) being used for said estimation step have an average occurrence frequency of more than one per five revolutions.

34. The apparatus according to claim 21, wherein

said means for analysing said first digital signal includes a burst rejector adapted to deliver any detected peak values (A_P) at a delivery frequency of f_es, wherein

f_es=e*f_ROT, wherein

f_ROT is said speed of rotation, and

e is a factor having a value of ten or less than ten.

35. The apparatus according to claim 34, wherein said burst rejector is adapted to deliver each peak amplitude value such that each delivered peak amplitude value reflects the highest amplitude value detected in the immediately preceding echo suppression period (T_es), said echo suppression period (T_es) being the inverse of said delivery frequency f_es.

36. The apparatus according to claim 21, further comprising

an input (42) for receiving an analogue measurement signal (S_EA) indicative of a vibration signal signature having a vibration frequency (f_SEA);

an A/D converter (40, 44) for generating a digital measurement signal (S_MD) dependent on the analogue measurement signal, said digital measurement signal (S_MD) having a first sample rate (f_S), the first sample rate being at least twice (k) said vibration frequency (f_SEA); and

wherein said first digital signal (S_MD, S_F, S_R, S_ENV) is dependent on, or identical with, said digital measurement signal (S_MD).

37. An apparatus for analysing the condition of a machine having a part rotating with a speed of rotation (f_ROT), comprising:

an input for receiving a first digital signal (S_MD) dependent on mechanical vibrations emanating from rotation of said part;

a peak detector (310) coupled to said input, said peak detector (310) being adapted to detect peak values (A_P) in said received first digital signal (S_MD, S_F, S_R, S_ENV), and

a burst rejector (330) is adapted to deliver output peak values (A_PO) on a burst rejector output (333) in response to said detected peak values (A_P); and

wherein

said burst rejector is adapted to control the delivery frequency of said output peak values (A_P, A_PO) such that said output peak values (A_P, A_PO) are delivered at a delivery frequency of f_es, wherein

f_es=e*f_ROT, wherein

f_ROT is said speed of rotation, and

e is a factor having a predetermined value.

38. The apparatus according to claim 37, wherein

the predetermined value of the factor e is ten or less than ten.

39. The apparatus according to claim 37, wherein

said burst rejector is adapted to deliver each output peak value such that each delivered peak amplitude value reflects the highest amplitude value detected in the immediately preceding echo suppression period (T_es), said echo suppression period (T_es) being the inverse of said delivery frequency f_es.

40. The apparatus according to claim 37, further comprising

means for receiving burst rejector output peak amplitude values (Ap) that have been collected during a finite time period (Pm), said finite time period corresponding to a certain amount (R) of revolution of said rotatable part;

said certain amount (R) of revolution corresponding to more than one revolution of said monitored rotatable part;

means for sorting said peak amplitude values (Ap) into a plurality (N_R) of amplitude ranges so as to reflect occurrence (N) of detected peak amplitude values (Ap) within said plurality of amplitude ranges; and

means for estimating a representative peak amplitude value (A_PR) in dependence on said sorted peak amplitude values (Ap) and said certain amount (R).