Method and apparatus for detecting rubbing in a rotary machine

• US 4,478,082 A
• Filed: 08/17/1982
• Issued: 10/23/1984
• Est. Priority Date: 08/26/1981
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ikeuchi, Kazuo, Sato, Ichiya, Koga, Tsuguaki, Hisano, Katsukuni, Yoneyama, Takao
• Primary Examiner(s): Gill, James J.
• Application Number:
  US06/408,949
• Time in Patent Office: 798 Days
• Field of Search: 73/587, 73/593, 73/658, 73/659, 73/660
• US Class Current: 73/593
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence
• CPC Class Codes: G01N 2291/014 Resonance or resonant frequency
• CPC Class Codes: G01N 2291/101 one transducer
• CPC Class Codes: G01N 2291/2693 Rotor or turbine parts
• CPC Class Codes: G01N 29/12 by measuring frequency or resonance of acoustic waves measuring frequency or resonant frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04, G01H13/00; acoustic resonators G10K11/04; vibration or shock testing of structures G01M7/00

Abstract

A method and apparatus for detecting the occurrence of rubbing in a rotary machine, in which at least one acoustic sensor is mounted on at least the rotor part or the stator part of the rotary machine, and the output signal from the acoustic sensor is detected and then filtered to extract a frequency component having a frequency substantially equal to the rotational frequency of the rotary machine, so as to detect the occurrence of rubbing in the rotary machine as early as possible and also to locate the source of the rubbing. Even when the occurrence of abnormal metal-to-metal contact at a bearing of the rotary machine is detected, it is discriminated from rubbing so that the occurrence of the rubbing can be reliably detected.

Claims

1. An apparatus for detecting the occurrence of rubbing in a rotary machine, comprising a rotary machine, at least one acoustic sensor installed on at least one of the rotor part and the stator part of the rotary machine for sensing an acoustic signal generated due to the occurrence of rubbing in the rotary machine, detector means for detecting the output signal from said acoustic sensor, means for fetching a frequency component having a frequency substantially equal to the rotation frequency of the rotary machine from the output signal from said detector means, display means for displaying the output signal from said fetching means, and abnormal metal-to-metal contact detecting means for detecting the occurrence of abnormal metal-to-metal contact at said bearing, said display means including a rubbing display unit displaying the output signal from said rubbing detecting means and an abnormal metal-to-metal contact display unit displaying the output signal from said abnormal metal-to-metal contact detecting means, wherein said rubbing detecting means includes a variable band-pass filter circuit fetching said frequency component from the output signal from said detector means and a first rectifier circuit rectifying the output signal from said variable band-pass filter circuit, and said abnormal metal-to-metal contact detecting means includes a low-frequency band-pass filter circuit receiving the output signal from said detector means, a second rectifier circuit rectifying the output signal from said band-pass filter circuit, and a comparator circuit comparing the output signals from said first and second rectifier circuits.

2. An apparatus according to claim 1, further comprising a rotation speed sensor sensing the rotation speed of the rotary machine, the output signal from said rotation speed sensor being applied to said variable band-pass filter circuit as a control input signal.

3. A method of detecting occurrence of rubbing in a rotary machine, comprising the steps of sensing an acoustic signal generated due to occurrence of rubbing in the rotary machine by at least one acoustic sensor disposed on at least one of the rotor part and the stator part of the rotary machine, detecting the output signal from said acoustic sensor, fetching a frequency component having a frequency substantially equal to the rotation frequency of the rotary machine from said detected signal, and displaying said fetched signal, further comprising the steps of rectifying the signal fetched by said fetching step, displaying said rectified signal on a rubbing display unit as a signal indicative of occurrence of rubbing, processing the signal detected by said detecting step, comparing said processed signal with said rectified signal, and displaying the signal indicative of the result of comparison on an abnormal metal-to-metal contact display unit as a signal indicative of occurrence of abnormal metal-to-metal contact at a bearing.

4. A method according to claim 3, wherein said processing step includes the steps of filtering said detected signal and rectifying said filtered signal.