Hitachi, Ltd.

Motoji Ohmori

Kazuo Sato

Masakazu Takasumi

Fumio Fujisawa

Motohiro Shiga

Kouki Shiohata

Koki Shiohata

Katsuaki Kikuchi

Ryoichi Kaneko

Kazuo Satoh

Disclosed is a method for detecting the condition of a crack generated in a rotor of a rotary machine during an operation thereof to check whether the crack is developing or not. The number of revolutions of the rotor and oscillations of journal end portions of the rotor born by the bearings are continually detected. The detection of the crack condition is made on the basis of the detected signal corresponding to the waveform of each half of at least one cycle of the detected rotor oscillation. Disclosed also is an apparatus for carrying out the method.

Method of and apparatus for detecting crack condition

A vibration diagnosis method and apparatus for rotary machines adapted for measuring the vibration of rotor shaft of a rotary machine, extracting the vibration component synchronous with the revolution of the rotor shaft from the measured vibration data, comparing the amplitude of the extracted vibration component with the amplitude of the overall vibration, analyzing the causes of the synchronous vibration component when the result of the comparison meets a predetermined reference, judging, in accordance with the result of the analysis, whether the vibration due to mass unbalance is attributable to an abrupt generation of mass unbalance or to a thermal bow of the rotor shaft, and displaying the result of the judgment. The analysis of the vibration component is made in real time or making use of data stored in the past.

Vibration diagnosis method and apparatus for rotary machines

A vibration diagnosis method for a rotary machine is disclosed. The presence or absence of a self-excited vibration is determined by checking if a rotating speed is in a rotating speed range which allows the occurrence of the self-excited vibration, if an amplitude of a frequency component corresponding to a first order critical speed is larger than a predetermined level, and if phases at characteristic points of vibration signals change among cycles.

Vibration diagnosis method for rotary machine

A method and apparatus for diagnosing a vibration in a rotor of the rotary machine including detecting the number of rotations and the vibration in the rotor when the rotor is rotating, extracting a vibration component synchronized with the number of rotations, determining whether the vibration component is normal or abnormal, calculating an abnormal vibration component through a vector operation by using the detected vibration component and a previously determined rotor vibration component in a normal state of the rotor, when the detected vibration component is judged to be abnormal, normalizing a vibration pattern of the abnormal vibration component, and determining an unbalance originating position in the rotor, which generates the abnormal vibration, by using a comparison of the normalized abnormal vibration pattern with a normalized vibration pattern of a previously determined unbalanced vibration.

Growing community of inventors

Hitachi, Japan

Motoji Ohmori