JPH08233975A - Device and method for detecting impact - Google Patents

Abstract

PURPOSE: To provide an impact detector which can detect impact signals in an object to be monitored with high precision. CONSTITUTION: After acceleration signals detected by acceleration detectors 1 are amplified to the level required for the analog signal processing through a preamplifier 2 and signal conditioners 3, they are outputted to a microprocessor 7 for signal processing operations by way of anti-aliasing filters 4 and analog-to-digital converters 5 and a single bus 6. In the microprocessor 7 for signal processing operations, filter processing is conducted for given time series data in the acceleration signals on the basis of two types of center frequencies, and then the two waveform data obtained are subjected to multiplication. Subsequently, it is judged whether the output level of the waveform data subjected to multiplication exceeds a prescribed trigger level and duration time or not, and then the data about detected impact are sent to a diagnosis computer 8 to process them for diagnoses.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock detecting device and method applied to a loose parts monitor device for detecting or diagnosing metallic loose parts generated or mixed in a pressure vessel or piping.

[0002]

2. Description of the Related Art Conventionally, for example, a part which is detached from a pressure vessel or the like which houses a core of a nuclear reactor used in a nuclear reactor plant and which contains a primary coolant of a gas or a liquid circulating in a primary cooling system. A loose parts monitor device is used to detect whether or not there are loose metal parts such as loose parts. This loose parts monitor device determines the presence or absence of loose parts by detecting an impact sound generated by vibration of loose parts or the like.

In the conventional abnormal vibration detection, 500 Hz to 10 shown in JP-A-56-154630 is used.
filter with a bandwidth of kHz and 0.07 Hz to 40
There is a method of performing a correlation analysis between outputs of a filter having a bandwidth of Hz and observing the result. As a result, the abnormal vibration is reliably detected even when there is much noise.

Further, there is a method disclosed in Japanese Patent Laid-Open No. 60-183591 for obtaining an FR value which is a ratio of an integrated value in a low frequency region and an integrated value in a high frequency region of a power spectrum density of a signal. In this method, the calculated FR value is calculated based on the known mass vs. FR.
The mass of the metallic loose parts is estimated by comparing with the correlation diagram of the values.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the abnormal vibration detection method disclosed in Japanese Patent No. 154630, detection processing is performed using an analog electronic circuit, and two bandpass filters and an analyzer are required for one channel signal. As the number of processing channels increases, the amount of material increases in proportion to the number of processing channels. Therefore, in a loose parts monitor device that generally needs to process signals of 10 to 20 channels at the same time, there is a drawback that the device cost increases. ing. Even if the analog electronic circuit is replaced with a digital circuit, a large amount of calculation is required to perform the bandpass filter processing and the correlation analysis performed by the analyzer with software. In the loose parts monitor device, real-time processing is indispensable for continuously monitoring an abnormal signal, and it is practical to simply replace the circuit in the example shown in Japanese Patent Laid-Open No. 56-154630 with software. It is difficult to perform real-time calculation.

The second example is a method of using the already detected impact signal for estimating the mass of the metallic loose parts.
Therefore, it is difficult to apply the method in the second example to the detection of the impact signal of the metallic loose parts.

The signals detected / measured by the loose part monitoring device are dark vibration components such as flow vibration of the cooling water flow in the pressure vessel and vibration of the equipment, that is, background noise and impact vibration of the loose metal parts. Are superimposed. Therefore, in order to detect the generation and mixing of loose parts with high accuracy, it is necessary to reliably detect the impact signal due to the metallic loose parts in the background noise. That is, the detection of the impact signal is indispensable for improving the monitoring ability of the loose parts monitor device and ensuring the reliability of the abnormality diagnosis result.

The present invention has been made in view of the above circumstances, and an impact detection device capable of clearly detecting an impact signal generated by an impact vibration of a metallic loose part with high accuracy and realizing cost reduction. The purpose is to provide.

[0009]

SUMMARY OF THE INVENTION The present invention is an impact detection device for detecting an impact by detecting a transient signal from noise components of a signal generated by an impact applied to a monitored object. In the above, in the time-series data in the signal generated by the impact given to the monitored object, the data at an arbitrary time point is subjected to a resonance type digital filter process based on two different center frequencies, and a filter means. Multiplier means for multiplying the two output waveforms obtained by the filter means, envelope means for obtaining an envelope waveform based on the product waveform from the product waveform output by the multiplier means, and envelope means for obtaining the envelope waveform. Means for providing a constant trigger level for the envelope waveform, the trigger level provided by this means, and the envelope Comparing means for comparing the output levels of the shapes, first counting means for counting the duration of the state when the comparing means determines that the output level of the envelope exceeds the trigger level, and the first counting means. The determining unit that determines whether the time counted by the counting unit 1 exceeds a certain duration, and the determining unit,
Output means for outputting impact detection information when it is determined that the time counted by the first counting means exceeds the predetermined duration, and after the impact detection information is output from this means and the envelope. Initialization means for returning the count value of the first counting means to 0 when the output level of the line waveform does not exceed the constant trigger level, and after the count value has been set to 0 by this initialization means And a second counting means for advancing the counting after the arbitrary time point.

Further, the present invention provides a shock detecting method for detecting the shock by detecting a transient signal from noise components of a signal generated by a shock applied to the monitored object, Of the time-series data in the signal generated by the impact given to the object, the data at an arbitrary time point is subjected to resonance type digital filter processing based on two different center frequencies,
The obtained two output waveforms are multiplied to obtain an envelope waveform based on the output product waveform, the output level of this envelope waveform is compared with a constant trigger level, and the output level of the envelope waveform is When the trigger level is exceeded, the time during which the state continues is counted, and when the constant duration is exceeded, the shock detection information is output, and the above-mentioned processing is performed by proceeding the count after the arbitrary time point. Is characterized by repeating.

[0011]

In the time-series data of the signal generated when the object to be monitored is impacted, the data at an arbitrary time point is filtered by the filter means based on two different center frequencies. Next, the data of the two waveforms output by this processing is multiplied by the multiplication means to generate the data of the product waveform. Envelope detection processing is performed by the envelope means on the generated product waveform data. As a result, envelope waveform data based on the product waveform data is generated and output to the comparison means.

Next, the means for giving the trigger level outputs the constant trigger level to the comparing means. The comparing means compares the trigger level with the output level of the envelope waveform data. Thus, when the output level exceeds the trigger level, the first counting means counts the duration of the state, and the determining means determines whether or not the duration exceeds the predetermined time. When the above duration exceeds a predetermined time, the output means outputs the shock detection information to the outside. After the impact detection information is output, the count value of the first counting means is returned to 0 by the initialization means. Next, the second counting means advances the counting after the arbitrary time point and repeats the above-described processing for the corresponding time series data.

As described above, a shock is generated by filtering the signal generated by the shock given to the monitored object with two different center frequencies and multiplying the generated two waveform data. Since the moment of is emphasized compared to the original signal, the impact occurrence can be clearly detected with high accuracy.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a loose parts monitor device equipped with an impact detection device according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 is an acceleration detector.
The acceleration detector 1 is generated, for example, in a pressure vessel (not shown) for accommodating the core of a nuclear reactor, etc., due to a collision between loose parts such as loose parts or loose parts and the pressure vessel. A signal in which the shock signal propagating through the outer wall of the container and the background noise resulting from the flow vibration of the cooling water flow in the pressure container are overlapped, that is, the acceleration signal is detected. Further, the acceleration detector 1 is connected to the preamplifier 2. In the preamplifier 2, the acceleration signal is converted into a voltage signal capable of long-distance transmission. This voltage signal is sent to a signal amplifier circuit, that is, the signal conditioner 3 and amplified to a level required for analog signal processing.

The voltage signal amplified by the signal conditioner 3 is input to the anti-aliasing filter 4 to remove the aliasing (frequency overlapping) phenomenon. In addition, the signal (analog signal) output after passing through the anti-aliasing filter 4 is
It is input to the A / D converter 5 and converted into digital time series data. A plurality of acceleration detectors 1 are attached to the pressure vessel. That is, a plurality of signal paths from the acceleration detector 1 to the A / D converter 5 are provided. That is, as shown in FIG. 1, a plurality of A / D converters 5 are connected via a signal bus 6 to an impact detection device, that is, in this embodiment, a signal processing arithmetic microprocessor 7 shown in FIG.

Next, the function of the signal processing arithmetic microprocessor 7 will be described. The signal processing arithmetic microprocessor 7 receives the kth data xk in the digital time series data output from the A / D converter 5,
Resonant type digital filter processing was performed based on two different types of center frequencies.
The output waveform data uk and vk are multiplied. Further, uk and vk are given by the following recurrence formula.

Uk = xk + a * uk-1 (1) vk = xk + b * vk-1 (2) In the above equations (1) and (2), a and b are the centers of the filter processing. It is a constant determined by the frequency and the resonance magnification.

In the multiplication process, the following calculation is performed to obtain the product waveform data yk. yk = uk × vk (3) Further, the microprocessor 7 performs envelope detection processing on the product waveform data yk obtained by the above multiplication processing, and the output level of the envelope waveform data zk obtained by this. Is compared with a constant trigger level w. The constant trigger level w is set in advance to eliminate the influence of the background noise in the pressure vessel. The microprocessor 7 determines that the output level of the obtained envelope waveform data zk is the trigger level w.
When the value exceeds, the value of the first counting means included therein, that is, the value of the counter T (not shown) representing the duration is increased. As a result, the time during which the output level exceeds the trigger level w is counted, and it is determined whether or not the duration time determination value d, which is a predetermined value, has been exceeded. This duration judgment value d
The (time threshold value) is set in advance for the purpose of preventing erroneous detection due to short-duration noise such as electric noise mixed in the microprocessor 7.

That is, the signal processing arithmetic microprocessor 7 determines that the signal of the detected envelope waveform data is a shock signal when the signal of the detected envelope waveform data has the time width of the trigger level w or more and the duration judgment value d or more. To detect.

The signal processing arithmetic microprocessor 7 is connected to a diagnostic computer 8. That is,
The impact detection information output from the signal processing arithmetic microprocessor 7 is sent to the diagnostic computer 8 to diagnose the impact occurrence in the pressure vessel. Further, the microprocessor 7 is provided with a counter T indicating the duration.
Separately from the above, a counter k indicating the time which is the second counting means.
(Not shown). In other words, the microprocessor 7 advances the value of the counter k and shifts to the processing for the (k + 1) th and subsequent time series data (for example, xk + 1) when the processing for xk is completed.

Next, the operation of the above embodiment will be described.
In the acceleration detector 1 of each channel shown in FIG. 1, an acceleration signal in which background noise is superimposed on an impact signal propagating on the outer wall of a pressure vessel (not shown) due to the generation and mixing of metallic loose parts is detected, and the preamplifier is detected. 2 and signal conditioner 3. Next, the amplified acceleration signal is sent to the A / D converter 5 via the anti-aliasing filter 4 and converted into digital time series data. Next, the signal of this time series data is sent to the signal processing arithmetic microprocessor 7 through the signal bus 6. Next, processing of an acceleration signal (time-series data) detected on any one of the paths of the respective channels shown in the figure and sent to the microprocessor 7 will be described with reference to FIGS. To do.

First, as shown in FIG. 2, the k-th data xk of the time series data is input to the signal processing arithmetic microprocessor 7 (step A1). The signal processing arithmetic microprocessor 7 receives the input xk
The resonance type digital filter processing (steps A2 and A3) shown in the equations (1) and (2) is simultaneously performed on the data of (2) with two types of center frequencies. As a result, the filtered k-th waveform data uk, v
k is obtained. Examples of actual waveform data obtained by the above filter processing are shown in FIGS. That is,
The impact signal generated in the pressure vessel shown in FIG. 7A and the background noise in FIG. 2B are superposed, that is, the signal shown in FIG. The waveform data uk and vk shown in FIGS. 8D and 8E are obtained by the processing of steps A2 and A3 described above. The waveform data uk and vk are in this case filtered by the center frequencies of 2.5 kHz and 10 kHz, respectively.

Next, with respect to the waveform data uk and vk respectively generated by the processing of the steps A2 and A3,
The multiplication process shown in the equation (3) is performed (step A).
4). As a result, as shown in FIG. 4A, the product waveform data yk of the waveform data uk and vk is obtained. Next, envelope detection processing is performed on the product waveform data yk (step A5), and the envelope waveform data zk shown in FIG. In the waveform data shown in FIGS. 3A to 3E and FIGS. 4A and 4B, the horizontal axis represents time and the vertical axis represents acceleration (relative value).

A constant trigger level w is given to the envelope waveform data zk (step A6),
Output level of waveform at zk and trigger level w
Is compared with (step A7). As a result, if zk> w, the value of the counter T representing the duration is increased to count the time during which the envelope waveform at zk exceeds the trigger level w (step A8). Next, the signal processing arithmetic microprocessor 7 compares the above-mentioned duration determination value d with the value of the counter T (step A9). As a result, when T> d, the microprocessor 7 causes the shock detection information,
That is, in the envelope waveform data zk shown in FIG.
A waveform that is higher than the trigger level w and that exceeds the duration determination value d, that is, information such as the maximum value of the impact waveform and the time of occurrence thereof is sent to the diagnostic computer 8 (step A10). The diagnostic computer 8 diagnoses the occurrence of impact in the pressure vessel based on the sent information. Next, the signal processing arithmetic microprocessor 7 resets the value of the counter T to 0 (step A11).

In step A7 described above, z
If k <w, the value of the counter T is reset to 0 (step A12). After the above processing is completed, the signal processing arithmetic microprocessor 7 advances the value of the counter k indicating the time (step A13). That is, the microprocessor 7 repeats the above-mentioned processing for xk + 1 which is the k + 1th time series data.

The signal processing arithmetic microprocessor 7 is not provided with a circuit for ending the processing. This is because the impact detection device according to the present invention is used for the purpose of continuously monitoring for a long period (for example, one year).

As described above, the signal processing arithmetic microprocessor 7 filters the time-series data in the acceleration signal detected in the pressure vessel based on two different center frequencies, and outputs the waveform data. Envelope detection processing is performed after multiplying uk and vk. Therefore, the product waveform data y in FIGS. 4A and 4B is obtained.
As indicated by k and the envelope waveform data zk, the signal at the moment of impact occurrence (for example, the signal at the time of 0.005 sec) is clearly output as compared with the acceleration signal shown in FIG.

That is, when a shock is generated by the loose parts, the natural frequency component of the device to be monitored (in this case, the pressure vessel) is excited, and a large number of frequency components are simultaneously generated in the shock vibration waveform. On the other hand, in the case of only background noise, the main component is a random signal component having no fixed phase relationship between each frequency component. Therefore, when the acceleration signal shown in FIG. 3 (c) detected by the acceleration detector 1 of the loose parts monitor device is filtered and multiplied according to the above-described process, a large number of frequency components are simultaneously generated to generate an impact. The moment of is emphasized compared to the acceleration signal, that is, the original signal. That is, FIG.
Since it is possible to reliably detect the impact signal shown in FIG. 7A included in the background noise of FIG. 6B, it is possible to clearly and highly accurately detect the impact occurrence due to loose parts in the pressure vessel or the like.

The location of the shock waveform, which was unclear in the acceleration signal of FIG. 3 (c), is clear in the envelope waveform data zk shown in FIG. 4 (b). 005 seconds). Therefore, also in this respect, the impact occurrence can be detected with high accuracy. As a result, the monitoring capability of the device is improved and the reliability of the diagnosis result can be secured.

Further, since the above-mentioned processing is performed by software, even if the number of channels in the loose parts monitor device shown in FIG. No need to add. Therefore, it is possible to reduce the cost of the signal processing portion of the loose parts monitor device, which generally requires multichannel processing of 10 to 20 channels.

Further, the impact detection device and method according to the present invention detects a transient signal from the noise components included in the signal. Therefore, the impact detection device and method, in addition to loose parts monitor device for detecting and diagnosing loose metal parts generated or mixed in the pressure vessel or piping, vibration, noise, temperature of the plant or mechanical device, It can also be applied to an abnormality diagnosis device that detects an abnormality occurrence in the above-mentioned plant or mechanical device from changes in the characteristics of signals due to measurement of various physical quantities such as pressure.

[0033]

As described above, according to the present invention,
The filter means filters the signal generated by the impact given to the monitored object based on two different center frequencies, and the multiplication means performs multiplication processing on the two waveform data obtained thereby. Therefore, from the noise component in the above signal, the transient signal,
That is, it becomes possible to clearly detect the shock signal. Therefore, it is possible to detect the impact occurrence on the monitored object with high accuracy.

[Brief description of drawings]

FIG. 1 is a device configuration diagram of a loose parts monitor device including an impact detection device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a flow of arithmetic processing in the signal processing arithmetic microprocessor according to the embodiment.

FIG. 3 is a diagram showing actual waveform data obtained by filtering an acceleration signal detected by an acceleration detector according to the embodiment based on two types of center frequencies.

FIG. 4 is a view showing a product waveform and envelope waveform data obtained by performing a multiplication process and an envelope detection process on waveform data generated by the filter process in the embodiment.

[Explanation of symbols]

 1 Acceleration detector 2 Preamplifier 3 Signal conditioner 4 Anti-aliasing filter 5 A / D converter 6 Signal bus 7 Microprocessor for signal processing operation 8 Diagnostic computer

Claims (2)

[Claims] 1. An impact detection device for detecting the impact by detecting a transient signal from a noise component of a signal generated by an impact applied to the monitored object, wherein The time-series data in the signal generated by the impact given by the filter, the data at an arbitrary time point is subjected to a resonance type digital filtering process based on two different center frequencies,
Multiplier means for multiplying the two output waveforms obtained by the filter means, envelope means for obtaining an envelope waveform based on the product waveform from the product waveform output by the multiplier means, and envelope means for obtaining the envelope waveform. Means for applying a constant trigger level to the envelope waveform, comparing means for comparing the trigger level given by this means with the output level of the envelope waveform, and the output level of the envelope by the comparing means. When it is determined that the trigger level has been exceeded, it is determined whether or not the first counting means counts the time for which the state continues, and whether or not the time counted by the first counting means exceeds a certain duration. The determining means and, when the determining means determines that the time counted by the first counting means exceeds the predetermined duration, the collision is detected. Output means for outputting detection information, and a count value of the first counting means after the impact detection information is output from this means and when the output level of the envelope waveform does not exceed the certain trigger level. Is provided with an initialization means for returning the count value to 0 and a second counting means for advancing the count after the count value is set to 0 by the initialization means. . 2. A shock detection method for detecting a shock by detecting a transient signal from noise components of a signal generated by a shock applied to a monitored object, wherein Of the time-series data in the signal generated by the shock given by the above, the data at an arbitrary time point is subjected to the resonance type digital filter processing based on two different center frequencies, and the obtained two output waveforms are multiplied. , An envelope waveform based on the output product waveform is obtained, the output level of this envelope waveform is compared with a constant trigger level, and when the output level of the envelope waveform exceeds the trigger level, the The time that the state continues is counted, and when it exceeds a certain duration, shock detection information is output, and the above-mentioned processing is performed by advancing the count after the arbitrary time point. A shock detection method characterized by repeating.