Apparatus for monitoring the condition of a machine
First Claim
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1. An apparatus for analysing the condition of a machine having a part rotatable with a speed of rotation, comprising:
- a transducer for generating an analogue measurement signal in response to machine vibration so that said analogue measurement signal includes a vibration signal signature havinga vibration frequency which is lower than an upper frequency limit value,at least one vibration signal repetition frequency, anda vibration signal amplitude;
an A/D converter (40, 44) adapted to generate a digital measurement signal (SMD, SR) having a sequence of sample values dependent on the analogue measurement signal, said digital measurement signal having a first sample rate that is at least twice said upper frequency limit value;
a digital peak value detector adapted to generate output peak values dependent on said sequence of sample values;
a peak value discriminator being adapted to sort said output peak values into corresponding amplitude ranges during a measuring session;
a measuring session controller adapted to control a variably settable duration of said measuring session;
a condition value generator adapted to generate a first condition value in response to said sorted output peak values and said durationso that said first condition value is indicative of a first amplitude value having a first predetermined occurrence rate, andso that said first condition value is based on a selected first temporal portion of the digital measurement signal;
a decimator adapted to generate a decimated digital signal in dependence of said digital measurement signal so that the decimated digital signal has a reduced sampling frequency; and
a Fourier Transformer adapted to generate a transformed signal in dependence of a selected second temporal portion of said decimated digital signal so that said transformed signal is indicative of said vibration signal repetition frequency,said apparatus being arranged to coordinate the generation of said transformed signal with the generation of the first condition valueso that the selected second temporal portion of said decimated digital signal is based substantially on said selected first temporal portion of the digital measurement signal, andso that said selected first temporal portion of the digital measurement signal is generated during the variably settable duration of said measuring session.
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Abstract
A method for analyzing the condition of a machine, and an apparatus for analyzing the condition of a machine are described.
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Citations
17 Claims
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1. An apparatus for analysing the condition of a machine having a part rotatable with a speed of rotation, comprising:
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a transducer for generating an analogue measurement signal in response to machine vibration so that said analogue measurement signal includes a vibration signal signature having a vibration frequency which is lower than an upper frequency limit value, at least one vibration signal repetition frequency, and a vibration signal amplitude; an A/D converter (40, 44) adapted to generate a digital measurement signal (SMD, SR) having a sequence of sample values dependent on the analogue measurement signal, said digital measurement signal having a first sample rate that is at least twice said upper frequency limit value; a digital peak value detector adapted to generate output peak values dependent on said sequence of sample values; a peak value discriminator being adapted to sort said output peak values into corresponding amplitude ranges during a measuring session; a measuring session controller adapted to control a variably settable duration of said measuring session; a condition value generator adapted to generate a first condition value in response to said sorted output peak values and said duration so that said first condition value is indicative of a first amplitude value having a first predetermined occurrence rate, and so that said first condition value is based on a selected first temporal portion of the digital measurement signal; a decimator adapted to generate a decimated digital signal in dependence of said digital measurement signal so that the decimated digital signal has a reduced sampling frequency; and a Fourier Transformer adapted to generate a transformed signal in dependence of a selected second temporal portion of said decimated digital signal so that said transformed signal is indicative of said vibration signal repetition frequency, said apparatus being arranged to coordinate the generation of said transformed signal with the generation of the first condition value so that the selected second temporal portion of said decimated digital signal is based substantially on said selected first temporal portion of the digital measurement signal, and so that said selected first temporal portion of the digital measurement signal is generated during the variably settable duration of said measuring session. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus for analysing the condition of a machine having a part rotatable with a speed of rotation, comprising:
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an input for receiving an analogue measurement signal indicative of a vibration signal signature having a vibration frequency and at least one repetition frequency; an A/D converter adapted to generate a digital measurement signal having a sequence of sample values dependent on the analogue measurement signal, said digital measurement signal having a first sample rate, wherein said vibration frequency is assumed to be lower than half of the first sample rate; a digital rectifier adapted to perform a rectification so as to generate a rectified digital signal dependent on said digital measurement signal; a digital peak value detector adapted to deliver output peak values on a peak value detector output dependent on said rectified digital signal; a peak value discriminator being adapted to sort said output peak values into corresponding amplitude ranges during a measuring session; a measuring session controller adapted to control a duration of said measuring session; a condition value generator adapted to generate a first condition value in response to said sorted output peak values and said duration so that said first condition value is based on a selected first temporal portion of the digital measurement signal; a decimator for performing a decimation of the rectified digital signal so as to achieve a decimated digital signal having a reduced sampling frequency; and a Fourier Tranformer adapted to generate a transformed signal in dependence on a selected second temporal portion of said decimated digital signal, said apparatus being arranged to coordinate the generation of said transformed signal with the generation of the first condition value so that the selected second temporal portion of said decimated digital signal is based substantially on said selected first temporal portion of the digital measurement signal.
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12. An apparatus for analysing the condition of a machine having a part rotatable with a speed of rotation, comprising:
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an input for receiving an analogue measurement signal indicative of a vibration signal signature having a vibration frequency and at least one repetition frequency; an A/D converter adapted to generate a digital measurement signal dependent on the analogue measurement signal, said digital measurement signal having a first sample rate, the first sample rate being at least twice said vibration frequency; a digital rectifier adapted to perform full-wave rectification so as to generate a rectified digital signal dependent on said digital measurement signal; a smoothing stage adapted to generate a smoothened digital signal dependent on said rectified digital signal, said smoothing stage being adapted to adjust an output sample amplitude value upwards in dependence on the amplitude of the corresponding input sample amplitude value and in dependence on the amplitude of temporally adjacent input sample amplitude values; an asymmetric digital filter for generating an asymmetrically low pass filtered signal in response to the smoothed digital signal, the asymmetric digital filter being adapted to generate the asymmetrically filtered signal so that in response to a detected positive time derivative of the smoothed digital a first settable filter value is set to a first value, and in response to a detected negative time derivative of the smoothed digital signal said first settable filter value (k) is set to a second value; and a peak value detector adapted to deliver output peak values on a peak value detector output in response to said detected peak values, wherein said peak value detector is adapted to limit the delivery frequency of said output peak values such that said output peak values are delivered at a maximum delivery frequency of fdP, where
fdP=fs/eand where fS is said first sample rate, and e is a number higher than two. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification