JPH0712640A - Abnormal sound detector - Google Patents

Abstract

(57) [Summary] [Structure] The sound detected by the acoustic sensor 32 installed in the casing of the pump 22 is passed through a bank filter 41 composed of a set of bandpass filters having various center frequencies,
The synchronization component extraction processing is performed by the synchronization component extraction processing unit 42 for each frequency band, and abnormal noise such as contact noise between the rotating body and the fixed portion buried in noise during operation such as gap resonance noise is detected with high sensitivity. , Monitor equipment for abnormal sounds. [Effect] Since the band elimination filter is not used for improving the SN ratio of the abnormal sound detection, even if the noise and the abnormal sound have the same frequency, only the abnormal sound can be selectively extracted, and the sensitivity of the abnormal sound detection device is improved. improves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention removes an acoustic component that is generated even during normal operation of an equipment from an output signal of an acoustic sensor installed in a plant equipment, and extracts only a sound that occurs during an abnormality to detect an abnormality. The present invention relates to an abnormal sound detection device suitable for achieving high sensitivity.

[0002]

2. Description of the Related Art In a conventional abnormal sound detector, for example, in order to monitor an abnormal sound of a pump, a normal pressure generated by measuring a pump differential pressure using a physical causal relationship between the differential pressure of the pump and the generated acoustic frequency. By predicting the frequency component of the sound of time and removing the predicted frequency component by signal processing, the detection sensitivity of the sound generated at the time of abnormality was improved. Research on diagnostic technology ”(1992.10).

[0003]

In the conventional abnormal sound detection device, since the sound generated at the normal time is predicted in advance from the pump differential pressure and the predicted frequency component is removed by the filter, the frequency band which does not need to be removed is eliminated. There is also a possibility of removing the signal component of, and in that case, even the frequency component of the abnormal sound may be removed to some extent, and not only the normal sound but also the abnormal sound level may be lowered.

It is an object of the present invention to provide an abnormal sound detecting device of a system which does not remove an abnormal sound component as much as possible when removing a normal sound.

[0005]

In order to achieve the above object, the present invention is a means for extracting only a component synchronized with the rotation of a pump from a detected sound, and a means for determining the presence / absence of abnormality from the magnitude of the synchronized component. Equipped with.

[0006]

With the knowledge that the synchronous component extracting means is a kind of resonance sound that is generated in the device under normal conditions and is not exactly synchronized with the rotation speed, the resonance sound and other sounds that are generated asynchronously with rotation. Is for removing. On the other hand, the abnormal sound of the rotating body is often generated by the forced force associated with the rotation. By extracting only the rotation synchronization component, the abnormal sound caused by the forced force accompanying the rotation can be detected. The means for detecting an abnormal sound from the magnitude of the synchronous component is a means for determining the presence / absence of an acoustic component which is the source of the forcing force associated with this rotation. By using these means, it is possible to distinguish the normal sound component that is currently occurring from the detected sound, so it is possible to avoid the reduction due to signal processing of abnormal sound that could not be avoided by the conventional prediction method. As a result, the abnormal sound detection sensitivity can be improved. Also, instead of prediction, a method of determining the occurrence of abnormal sound from the detected sound itself will be adopted, so that it is not necessary to remove other frequency components that do not actually occur but are raised as candidates for prediction,
Further, it is effective in improving the detection sensitivity.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows an example in which the present invention is applied to a pump used in a nuclear power plant. Pump 2 of equipment to be monitored
Reference numeral 2 serves to take out the cooling water inside the reactor vessel 1 once and inject it again into the inside of the reactor vessel 1. The pump 22 is driven by the motor 21. The rotating shafts of the pump 22 and the motor 21 are directly connected, and the number of rotations thereof is detected by the rotation sensor 31. Also, pump 2
The acoustic wave propagating through the second casing is detected by the acoustic sensor 32. The rotational speed signal and the acoustic signal that have been detected are subjected to waveform shaping and amplification processing by the tachometer 33 and the charge amplifier 34, respectively. Charge amplifier 3
The acoustic signal as the output of No. 4 passes through a bank filter including a large number of band pass filters, and an output corresponding to each center frequency is obtained. The synchronization component extraction processing unit 42 integrates the detection signals of the acoustic waves according to the rotation reference timing, and extracts only the rotation synchronization component. The single-component abnormality detection unit 43 has a function of determining the presence or absence of abnormality for each center frequency of the bandpass filter. On the other hand, the all-component abnormality detection unit 44 has a function of determining the presence / absence of abnormality on the basis of the synchronous component extraction data of all observed frequency bands.

With reference to FIG. 2, the operation of the synchronization component extraction processing section 42, which is the main component of the abnormal sound detection apparatus of the present invention, will be described. It is the image figure of the time change of an acoustic signal and a rotation speed signal. The rotation speed signal becomes 1 around the reference angle, and one pulse is generated per rotation. Therefore, it is possible to read the time axis as the angle of the pump rotation axis, and the read rotation angle is also shown. The lower part of FIG. 2 shows the result obtained by averaging the temporal changes in the acoustic data for each rotation angle based on the rotation angle and arranging the average sound level for each rotation angle. By averaging the acoustic data for each rotation angle, the sound that always occurs at the same rotation angle even if the amplitude is small is relatively louder than the sound that does not occur at the same angle even if the amplitude is large. Become. By utilizing this fact, only the component synchronized with the rotation can be selectively extracted. The synchronization component extraction unit 42 extracts the synchronization component by executing the processing procedure shown in FIG.

Next, the operation will be described in more detail based on the flow of signal processing. FIG. 3 shows a signal waveform of a main part when a performance test is carried out to confirm the effectiveness of the abnormal sound detection device of the present invention. FIG. 3A is a simulated waveform of a gap resonance sound (a sound generated by the flow shown in the literature is referred to as below). (B) is a simulated waveform of the contact sound that is simulated assuming that the impeller of the pump 22 and the casing come into contact with each other once per rotation, and a contact sound is generated.
The frequencies of (a) and (b) are almost the same.
(C) is a simulated waveform of an acoustic signal when both are added and detected by the acoustic sensor 32. Acoustic signal (c)
The amplitude of is governed by the gap resonance sound, and it is not known that contact sound is mixed. Therefore, the gap resonance sound is monitored only by monitoring the acoustic wave. When the frequency of the gap resonance sound is predicted and removed by the band elimination filter, the contact sound itself is also removed because the frequencies are almost the same. (D) shows the result of the synchronous component extraction processing, in which a slight gap resonance sound remains,
The contact sound is relatively loud and detected. As described above, according to the present invention, even when the frequencies of the gap resonance sound and the abnormal sound to be detected match, the abnormal sound can be detected.

In the example of FIG. 3, the synchronous component extraction processing is directly performed on the raw signal of the acoustic signal, but it is of course applicable to the signal after detection. Further, as can be seen from this explanation, the sensitivity can be made higher with the bank filter 41, but the abnormal sound can be detected even without the bank filter 41.

The single component abnormality detecting section 43 sets a threshold value for each frequency band using the result after the synchronous component extraction processing, and when the threshold value is exceeded, it is determined to be abnormal.
Further, the all-component abnormality detection unit 44 adds the respective components after the synchronous component extraction processing, sets threshold values for all components, and determines that the components are abnormal when the threshold values are exceeded. The former can detect abnormalities of specific frequency components with high sensitivity,
The latter is effective when the frequency spectrum of the abnormal sound is wide.

The device can be realized by both an analog circuit and a digital circuit. It is also possible to realize it by combining both circuits.

In the embodiment, (1) Since the sensitivity of abnormal sound detection can be increased by separating the acoustic signal for each frequency component by the bank filter in advance, the performance of the abnormal sound monitoring device is improved.

(2) Since it is not necessary to grasp the relationship between the pump differential pressure and the clearance resonance sound frequency in advance by experiments, etc., it is not necessary to investigate and examine the installation of an abnormal sound monitoring device, and manpower can be reduced. Therefore, the economical efficiency of the abnormal sound monitoring device is improved.

(3) Since the abnormal sound detection unit separates the abnormal sound detection from the single frequency component and the abnormal sound detection from all the frequency components, the target abnormal sound detection range is widened. The performance of the detection device is improved.

[0017]

As described above, according to the present invention, the removal of the gap resonance sound component which is a problem in the abnormal sound detection can be reduced without using the frequency removal filter. As a result, the sensitivity of the abnormal sound detection can be improved and the abnormal sound can be detected. The sensitivity of the detection device is improved.

[Brief description of drawings]

FIG. 1 is a block diagram in which the present invention is applied to acoustic monitoring of a pump of a nuclear power plant.

FIG. 2 is an explanatory diagram illustrating a procedure of synchronous component extraction processing.

FIG. 3 is an explanatory diagram showing an effect of a synchronous component extraction process.

[Explanation of symbols]

1 ... Reactor vessel, 21 ... Motor, 22 ... Pump, 31 ...
Rotation speed sensor, 32 ... Acoustic sensor, 33 ... Tachometer, 34
Charge amplifier 41 41 Bank filter 42 Synchronous component extraction processing unit 43 Single component abnormality detection unit 44 All component abnormality detection unit

Claims (5)

[Claims] 1. A means for detecting the sound of a plant equipment, a timing signal detecting means for knowing the timing of sound generation, a means for accumulating sound signals in synchronization with the timing signal, and a cumulative signal having a set level. An abnormal sound detecting device comprising: an abnormal sound discriminating means for judging that an abnormal sound is generated when the sound exceeds the abnormal sound. 2. An abnormal sound detecting device according to claim 1, wherein a bank filter composed of bandpass filters having different center frequencies is added in front of the accumulating means for acoustic signals. 3. An abnormal sound detecting device according to claim 1 or 2, further comprising acoustic signal detection means before the acoustic signal accumulation means. 4. An abnormal sound detecting device according to claim 2, further comprising means for judging occurrence of abnormal sound for each single frequency component and means for judging occurrence of abnormal sound for all frequency components. 5. The abnormal sound detection device according to claim 1, 2, 3, or 4, wherein the plant device is a pump, and the sound generation timing signal is a rotation speed signal.