Analysis system
First Claim
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1. An apparatus for analysing the condition of a machine having a part rotating with a speed of rotation, comprising:
- a first sensor adapted to generate an analogue measurement signal dependent on mechanical vibrations emanating from rotation of said part;
an analogue-to-digital converter for sampling said analogue measurement signal at a sampling frequency so as to generate a digital measurement data signal in response to said analogue measurement signal;
a filter adapted to generate a filtered digital data signal dependent on said digital measurement data signal;
a digital rectifier adapted to generate a rectified signal dependent on said filtered digital data signal;
a first decimator for performing a decimation of the rectified signal so as to achieve a first digital signal having a first reduced sampling frequency;
said first decimator including low pass filtering;
a fractional decimator, said fractional decimator havinga first input for receiving said first digital signal anda second input for receiving a signal indicative of a relevant variable speed of rotation associated with said rotating part;
a third input for receiving a signal indicative of an output sample rate setting signal;
said fractional decimator being adapted to generate a second digital signal having a second reduced sampling frequency such that the number of sample values per revolution of said rotating part is kept at a substantially constant value;
said fractional decimator generating said second digital signal in response tosaid first digital signal,said signal indicative of a relevant variable speed of rotation; and
said signal indicative of an output sample rate setting signal;
the apparatus further comprisingan evaluator adapted to perform a condition analysis function for analysing the condition of the machine dependent on said second digital signal.
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Abstract
A method for analyzing the condition of a machine having a rotating shaft, including:
- generating an analog electric measurement signal (SEA) dependent on mechanical vibrations emanating from rotation of the shaft;
- sampling the analog measurement signal at a sampling frequency (fS) so as to generate a digital measurement data signal (SMD) response to the received analog measurement data;
- performing a decimation of the digital measurement data signal (SMD) so as to achieve a digital signal (SRED) having a reduced sampling frequency (fSR1, fSR2); wherein the decimation includes the step of
- controlling the reduced sampling frequency (fSR1, fSR2) such that the number of sample values per revolution of the shaft (8) is kept at a substantially constant value; and
- performing a condition analysis function (F1, F2, Fn) for analyzing the condition of the machine dependent on the digital signal (SRED) having a reduced sampling frequency (fSR1, fSR2).
43 Citations
34 Claims
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1. An apparatus for analysing the condition of a machine having a part rotating with a speed of rotation, comprising:
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a first sensor adapted to generate an analogue measurement signal dependent on mechanical vibrations emanating from rotation of said part; an analogue-to-digital converter for sampling said analogue measurement signal at a sampling frequency so as to generate a digital measurement data signal in response to said analogue measurement signal; a filter adapted to generate a filtered digital data signal dependent on said digital measurement data signal; a digital rectifier adapted to generate a rectified signal dependent on said filtered digital data signal; a first decimator for performing a decimation of the rectified signal so as to achieve a first digital signal having a first reduced sampling frequency;
said first decimator including low pass filtering;a fractional decimator, said fractional decimator having a first input for receiving said first digital signal and a second input for receiving a signal indicative of a relevant variable speed of rotation associated with said rotating part; a third input for receiving a signal indicative of an output sample rate setting signal; said fractional decimator being adapted to generate a second digital signal having a second reduced sampling frequency such that the number of sample values per revolution of said rotating part is kept at a substantially constant value;
said fractional decimator generating said second digital signal in response tosaid first digital signal, said signal indicative of a relevant variable speed of rotation; and said signal indicative of an output sample rate setting signal;
the apparatus further comprisingan evaluator adapted to perform a condition analysis function for analysing the condition of the machine dependent on said second digital signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An apparatus for analysing the condition of a machine having a part rotating with a speed of rotation, comprising:
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a first sensor adapted to generate an analogue measurement signal dependent on mechanical vibrations emanating from rotation of said part; an analogue-to-digital converter for sampling said analogue measurement signal at a sampling frequency so as to generate a digital measurement data signal in response to said analogue measurement signal; a digital rectifier adapted to generate a digitally rectified signal dependent on said digital measurement data signal; an input for receiving a value indicative of a speed of rotation of said rotating part; a fractional decimator adapted to perform a decimation of the digital measurement data signal so as to generate a decimated digital signal having a reduced sampling frequency;
said fractional decimator including low pass filtering; and
said fractional decimator being adapted to control the reduced sampling frequency in dependence of the value indicative of a speed of rotation such that the number of sample values per revolution of said rotating part is kept at a substantially constant value in said decimated digital signal;an evaluator adapted to perform a condition analysis function for analysing the condition of the machine dependent on said decimated digital signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification