| 摘要 |
PURPOSE:To reduce the size and weight of a device by providing a band extracting circuit which extracts a necessary band component from an acoustic sensor output signal, a low-frequency component extracting circuit which extracts an envelope signal from the output of the circuit, etc. CONSTITUTION:Acoustic sensors 1 are fitted to many rotary machines of the same type, and the values of A/D conversion 9 of their outputs are measured, their mean value (monitor value) is stored in a storage part 12. Then the signal from the sensor 1 fitted to an object machine to be measured is amplified 2 and a BPF 3 extracts a signal in a frequency band where the influence of noises, etc., is a little. Then the envelope signal of the signal is extracted by an RMS circuit 4. This envelope signal contains a frequency component based upon periodic and impulsive force generated owing to the presence of the waving of the track surface of a bearing, etc. here, the envelope signal is passed through a BPS 5, then averaged by an RMS circuit 8, and A/D converted 9 before being inputted to a microcomputer 10. The microcomputer 10 stores data (measured value) from the converter 9 in the storage part 12, also takes a diagnosis based upon the monitor value and measured value, and displays the diagnostic result on a display part 11.
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