| 摘要 |
PURPOSE:To apply the same criterion to many machines by detecting the sound pressure of a machine and finding an acoustic spectrum within a specific frequency range according to the detected sound pressure, and correcting it with a variation acoustic spectrum found by performing measurement several times. CONSTITUTION:A sound pressure sensor 1 detects the sound pressure of the object machine to be diagnosed, the output of the sensor 1 is amplified 2, and a signal of specific frequency is passed through a filter 3; and an effective value circuit 5 obtains an effective value, which is A/D-converted 6, inputted to a microcomputer 7, and stored in a memory 9. In this constitution, the acoustic spectrum inputted to the microcomputer 7 is stored in the memory 9 while having a specific sound pressure level SPL(n). Further, the mean value of (m) measured sound pressure level is calculated, its standard deviation SPLsigma(n) is found and corrected as a corrected acoustic spectrum, and then the acoustic spectrum SPLa(n) is found from SPLa(n)=SPL(n)-SPLsigma(n). This spectrum SPLa(n) is reduced in the influence of the sound of the machine and variance in measurement, so the diagnosing ability is improved.
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