DIAGNOSTIC METHOD AND DIAGNOSTIC DEVICE FOR A SLIDE BEARING

• US 20130006551A1
• Filed: 02/21/2011
• Published: 01/03/2013
• Est. Priority Date: 03/03/2010
• Status: Active Grant

• Current Assignee: Asahi Kasei Engineering Corporation (Asahi Kasei Corporation)
• Original Assignee: Asahi Kasei Engineering Corporation (Asahi Kasei Corporation)
• Inventors: Sako, Takashi, Tamura, Kouichi
• Granted Patent: US 9,588,015 B2
• Time in Patent Office: Days
• US Class Current: 702/56
• CPC Class Codes: G01H 1/14 Frequency
• CPC Class Codes: G01M 13/045 Acoustic or vibration analysis

Abstract

A sign of a minor rubbing abnormality of a slide bearing in a diesel engine is accurately detected. In order to realize the accurate detection, the following is performed: detecting waveform data which represents an acceleration of a vibration which occurs when a slide bearing is in operation; transforming acceleration waveform data into an acceleration spectrum of a frequency domain by applying a Fourier transform to the acceleration waveform data; quantifying a plurality of peak information which occurs at a rotational frequency interval of a shaft to be measured in the acceleration spectrum by performing a predetermined signal process combined with rotational frequency information of the shaft; obtaining a characteristic value; monitoring whether the obtained characteristic value has exceeded a predetermined threshold value; and when the characteristic value has exceeded the threshold value, determining that an abnormality has occurred in the slide bearing.

Claims

1. A diagnostic method for a slide bearing, comprising:

detecting waveform data which represents an acceleration of a vibration which occurs when a slide bearing is in operation;

transforming acceleration waveform data into an acceleration spectrum of a frequency domain by applying a Fourier transform to the acceleration waveform data;

quantifying a plurality of peak information which occurs at a rotational frequency interval of a shaft to be measured in the acceleration spectrum by performing a predetermined signal process combined with rotational frequency information of the shaft;

obtaining a characteristic value;

monitoring whether the obtained characteristic value has exceeded a predetermined threshold value; and

when the characteristic value has exceeded the threshold value, determining that an abnormality has occurred in the slide bearing.

2. The diagnostic method for a slide bearing according to claim 1, further comprising:

performing a cepstrum calculation which applies an inverse Fourier transform to the acceleration spectrum after a logarithmic transformation;

obtaining time series data of a quefrency value obtained from the waveform data after the cepstrum calculation;

monitoring whether the quefrency value has exceeded the predetermined threshold value; and

when the quefrency value has exceeded the threshold value, determining that an abnormality has occurred in the slide bearing.

3. The diagnostic method fora slide bearing according to claim 1, further comprising:

performing a calculation which determines an auto-correlation of the acceleration spectrum;

monitoring whether a value of the auto-correlation obtained by the calculation has exceeded the predetermined threshold value;

when the value of the auto-correlation has exceeded the threshold value, determining that an abnormality has occurred in the slide bearing.

4. The diagnostic method for a slide bearing according to claim 1, further comprising:

performing a calculation which determines a cross-correlation between the acceleration spectrum and a predetermined spectrum;

monitoring whether a value of the cross-correlation obtained by the calculation has exceeded the predetermined threshold value;

when the value of the cross-correlation has exceeded the threshold value, determining that an abnormality has occurred in the slide bearing.

5. The diagnostic method for a slide bearing according to claim 1, wherein data of a frequency domain of 1 k to 30 kHz is detected as data which represents the vibration acceleration.

6. The diagnostic method for a slide bearing according to claim 1, wherein data of a frequency domain of at least 1 k to 10 kHz is detected as data which represents the vibration acceleration.

7. The diagnostic method for a slide bearing according to claim 4, further comprising:

preparing, in advance, a predetermined artificial spectrum having a peak for every rotational frequency of the shaft as the spectrum of the frequency domain of the vibration acceleration;

calculating a cross-correlation between the artificial spectrum and the acceleration spectrum; and

calculating a characteristic value in a predetermined frequency range comprising the highest frequency domain of the cross-correlation.

8. The diagnostic method for a slide bearing according to any one of claims 1-7, wherein the slide bearing of a diesel engine is a target to be diagnosed.

9. A diagnostic device for a slide bearing which diagnoses an abnormality such as a rubbing in the slide bearing, comprising:

a revolution speed detection sensor which detects a revolution speed of a rotating shaft;

an acceleration sensor which detects an acceleration during a vibration of the rotating shaft;

a monitoring device which;

transforms waveform data which represents an acceleration of a vibration detected by the acceleration sensor into waveform data of a frequency domain by applying a Fourier transform to the waveform data;

quantifies a plurality of peak information which occurs at a rotational frequency interval in the waveform data of the frequency domain with an arithmetic unit which quantifies by performing a predetermined signal process combined with rotational frequency information;

obtains a characteristic value;

monitors whether the characteristic value has exceeded a predetermined threshold value; and

when the characteristic value has exceeded the threshold value, determines that an abnormality has occurred in the slide bearing; and

a reporting device which outputs a determination result to the outside when the monitoring device has determined that an abnormality has occurred in the slide bearing.

10. The diagnostic device for a slide bearing according to claim 9, wherein a cepstrum analysis of a characteristic value is applied.

11. The diagnostic device for a slide bearing according to claim 9, wherein an auto-correlation analysis of a characteristic value is applied.

12. The diagnostic device for a slide bearing according to claim 9, wherein a cross-correlation analysis of a characteristic value is applied.

13. The diagnostic device for a slide bearing according to any one of claims 9-12, wherein a slide bearing of a diesel engine is a target to be diagnosed.