Method and apparatus for analyzing rotating machines

An apparatus for determining an indicator of a condition of a rolling element bearing enclosed in a housing of a rotating machine, the apparatus comprising:

• a vibration transducer means in contact with said housing means for sensing mechanical vibrations of the rotating machine and converting the sensed vibrations into an analog signal proportional to the sensed vibrations;
• an analog-to-digital convertor means for converting the analog signal into a digital signal;
• a means for converting the digital signal into a frequency spectrum;
• an analyzing means for analyzing the frequency spectrum to identify frequency components characteristic of problems other than bearing defects;
• a means for eliminating the frequency components related to problems other than bearing defects;
• a means for selecting a remaining frequency component having a highest amplitude as the indicator of the rolling element bearing condition.

An apparatus for determining a vibration signal frequency component indicative of a condition of a rolling element bearing of a rotating machine, the apparatus comprising:

• a vibration detector means for detecting and converting vibrations in the rotating machine into an electrical signal proportional to the vibrations;
• a filtering means for filtering the electrical signal to obtain select frequencies;
• an analog-to-digital convertor means to convert the electrical signal into a digital signal;
• a means for converting the digital signal into a frequency spectrum;
• a selecting means for selecting frequency components of the frequency spectrum characteristic of running speed and frequency components that are random, spurious and caused by other effects;
• an eliminating means for eliminating the frequency components that are random, spurious and caused by other effects;
• a determining means for determining running speed from the frequency components remaining after the step of eliminating the frequency components that are random, spurious and caused by other effects;
• a means for analyzing the frequency spectrum to identify frequency components characteristic of problems other than bearing defects;
• an eliminating means for eliminating the frequency components related to problems other than bearing defects;
• a means for storing a plurality of remaining frequency components which are not eliminated by the eliminating means;
• an averaging means for averaging corresponding stored frequency components to produce a plurality of averaged frequency components;
• and,
• a means for selecting an averaged frequency component having a highest amplitude as the frequency components indicative of the rolling element bearing condition.

An apparatus for determining bearing condition comprising:

• a vibration sensor for sensing vibration arising from a rolling element bearing and generating an electrical signal indicative thereof;
• a running speed calculating means for calculating a running speed of the rolling element from the electrical signal including:
• a transform means for transforming the electrical signal into a frequency spectrum including a plurality of frequency bins, each bin having a preselected frequency band, a center frequency, and a magnitude indicative of a strength of sensed frequency components within the corresponding frequency band,
• a means for identifying a set of frequency bins in which the center frequencies are even multiples of each other and in which the collective amplitudes of the frequency bins exceed the amplitude of other sets of frequency bins with center frequencies that are even multiples of each other, and
• a means for selecting the lowest center frequency of the identified set as the running speed;
• and
• a bearing condition means for generating a bearing condition indicating signal from the electrical signal and the selected lowest center frequency.

A method for determining an indicator of a condition of a rolling element bearing from a vibration signal obtained from a rotating machine, the method comprising:

• a) converting vibrations in the rotating machine into an electrical signal proportional to the vibrations;
• b) filtering the electrical signal;
• c) converting the electrical signal into a digital signal;
• d) converting the digital signal into a frequency spectrum;
• e) selecting frequency peaks of the frequency spectrum characteristic of an actual running speed of the rotating machine, and frequency components that are random, spurious and caused by other effects;
• f) eliminating the frequency components that are random, spurious and caused by other effects;
• g) calculating a final running speed signal representing the actual running speed, from the frequency peaks remaining after the eliminating step;
• h) analyzing the frequency spectrum to identify frequency peaks characteristic of problems other than bearing defects;
• i) eliminating the frequency peaks related to problems other than bearing defects;
• j) storing frequency peaks remaining after the step of eliminating problems other than bearing defects;
• k) repeating at least steps (h), (i), and (j) to store a plurality of frequency peaks;
• l) averaging corresponding stored frequency peaks;
• and
• m) selecting an averaged frequency peak having a highest amplitude as the indicator of the rolling element bearing condition.

A method for determining an indicator of a condition of a rolling element bearing from a vibration signal obtained from the rotating machine, the method comprising:

• converting vibrations in the rotating machine into an electrical signal proportional to the vibrations;
• filtering the electrical signal;
• converting the electrical signal into a frequency spectrum;
• selecting (i) frequency peaks of the frequency spectrum which are characteristic of an actual running speed of the rotating machine and (ii) frequency peaks that are random, spurious and caused by other effects by:
• selecting frequency peaks in the frequency spectrum to be designated as significant peaks, when the peaks are at least 0.005 in/sec, are at least as high as a next lower frequency peak, and are higher than a next higher frequency peak,
• selecting such significant peaks
• in a first band of frequencies 20% less than a nominal speed setting to 10% more than the nominal speed setting,
• in a second band of frequencies 20% less than two times the nominal speed setting to 10% more than two times the nominal speed setting, and
• in a third band of frequencies 20% less than three times the nominal speed setting to 10% more than three times the nominal speed setting;
• eliminating frequency peaks that are random, spurious and caused by other effects;
• determining a calculated final running speed corresponding to the actual running speed, from the frequency peaks remaining after the eliminating step;
• analyzing the frequency spectrum to identify frequency peaks characteristic of problems other than bearing defects;
• eliminating the frequency peaks related to problems other than bearing defects;
• selecting a remaining frequency peak having a highest amplitude as the indicator of the rolling element bearing condition.