To provide a method of diagnosing anomalies in low speed rotational bearings of elevators, which allows for accurate diagnosis of anomalies in a low speed rotational bearing even if a frequency of vibration generated by the low speed rotational bearing is mixed in a frequency band of operational vibration of rational machinery and external vibration.
Mechanical vibration generated by rotation of a low speed rotational bearing 5 of an escalator is detected by a vibration acceleration sensor 11, and a detection signal is amplified, fast Fourier transformed, and fed to a weight setting unit 14 which applies weight setting processing on the fast Fourier transformed result according to vibration frequency bands. By knowing characteristic vibration frequency bands (diagnostic bands) generated by the bearing 5 under diagnosis in normal and abnormal condition in advance, weight factors for the diagnostic bands are maximized in the weight setting processing. Since frequencies of mechanical vibration of the escalator and external vibration are not in the diagnostic bands, weight factors for those frequencies are made relatively low, which improves S/N ratio.
ATSUZAWA TERUYOSHI
IGARASHI YOSHIHARU
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